INTRODUCTION
⌅The lefteye flounders of the family Bothidae are a large group of marine fishes living in tropical and temperate waters of all oceans. They are arranged in the order Pleuronectiformes ( Nelson et al. 2016 Nelson J.S., Grande T.L., Wilson M.V.H. 2016. Fishes of the world. Fifth edition. John Wiley and Sons, Hoboken, NJ, USA, xli + 707 pp. https://doi.org/10.1002/9781119174844 ) and currently contain a total of 168 valid species ( Fricke et al. 2022a Fricke R., Eschmeyer W.N., Fong J. 2022a. Genera/species by family/subfamily in Eschmeyer’s catalog of fishes, electronic version (6 June 2022). Internet publication, San Francisco (California Academy of Sciences). http://research.calacademy.org/research/Ichthyology/Catalog/fishcatmain.asp ). The Bothidae are characterized by the presence of myorhabdoi (intermuscular bones), which is a synapomorphy of the family ( Hensley 1977 Hensley D.A. 1977. Larval development of Engophrys senta (Bothidae), with comments on intermuscular bones in flatfishes. Bulletin of Marine Science 27: 681-703., Chapleau 1993 Chapleau F. 1993. Pleuronectiform relationships: a cladistic reassessment. Bulletin of Marine Science 52: 516-540.). The Bothinae (now classified as the family Bothidae) were characterized by Norman (1934) Norman J.R. 1934. A systematic monograph of the flatfishes (Heterosomata). Volume 1. Psettodidae, Bothidae, Pleuronectidae. British Museum (Natural History): viii + 459 pp. https://doi.org/10.5962/bhl.title.8585 as left-sided flounders with the pelvic fin on the blind side short-based, that on the ocular side elongate, extending forward to the urohyal, supported by a cartilaginous plate placed in advance of the cleithra, its anterior ray well in advance of first ray of that of the blind side, and caudal vertebrae with well-developed apophyses.
The genus Arnoglossus Bleeker, 1862 Bleeker P. 1862. Sur quelques genres de la famille des Pleuronectoïdes. Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen, Afdeling Natuurkunde, 13: 422-429. was originally described by Bleeker (1862: 427) Bleeker P. 1862. Sur quelques genres de la famille des Pleuronectoïdes. Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen, Afdeling Natuurkunde, 13: 422-429. and briefly diagnosed as having the lateral line anteriorly strongly curved, the eyes on the left side of the body, and two preanal spines. The genus was redefined by Amaoka (1969) Amaoka K. 1969. Studies on the sinistral flounders found in the waters around Japan: taxonomy, anatomy and phylogeny. J. Shimonoseki Univ. Fish. 18: 65-340. as having the pelvic fin on the ocular side beginning at the tip of the isthmus, the eyes separated by a bony ridge or a very narrow concave space in the anterior half, interorbital equally wide in both sexes, head large, more than 22% of standard length (SL), the scales on the ocular side cycloid or feebly ctenoid, and the mouth large, maxillary longer than eye diameter. The genus is distributed in the eastern Atlantic and the Indo-Pacific. It currently includes a total of 35 valid species ( Fricke et al. 2022b Fricke R., Eschmeyer W. N., Laan R. van der (eds) 2022b. Eschmeyer’s catalog of fishes, electronic version (6 June 2022). Internet publication, San Francisco (California Academy of Sciences). http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp ); a list of these species and their distribution is provided in Table 1 . However, several authors have noted that Arnoglossus is somewhat heterogeneous and is apparently not monophyletic, so it is in need of further revision ( Norman 1934 Norman J.R. 1934. A systematic monograph of the flatfishes (Heterosomata). Volume 1. Psettodidae, Bothidae, Pleuronectidae. British Museum (Natural History): viii + 459 pp. https://doi.org/10.5962/bhl.title.8585 , Fukui 1997 Fukui A. 1997. Early ontogeny and systematics of Bothidae, Pleuronectoidei. Bulletin of Marine Science, 60: 192-212.).
| Species | Depth range (m) | Geographical distribution | Remarks |
|---|---|---|---|
| A. coeruleosticta (Steindachner, 1898) | shallow | EP: Juan Fernandez and Desaventurados Islands | |
| A. andrewsi Kurth, 1954 | 6-38 | EI, WP: Bass Strait and Tasmania, Australia | |
| A. yamanakai Fukui, Yamada and Ozawa, 1988 | 20-30 | WP: East China Sea | |
| A. grohmanni (Bonaparte, 1837) | 1-50 | MS: Mediterranean and Black Sea | Junior synonym: A. kessleri Schmidt, 1915 |
| A. nigrofilamentosus Fricke, Golani and Appelbaum-Golani, 2017 Fricke R., Golani D., Appelbaum-Golani B. 2017. Arnoglossus nigrofilamentosus n. sp., a new species of flounder (Teleostei: Bothidae) from off the Mediterranean coast of Israel, probably a new case of Lessepsian migration. Sci. Mar. 81: 257-265. https://doi.org/10.3989/scimar.04684.07A | 20-40 | RS: probably Gulf of Suez. MS: southeastern Mediterranean | |
| A. fisoni Ogilby, 1898 | 26-50 | WP: New South Wales and Queensland, Australia | |
| A. micrommatus Amaoka, Arai and Gomon, 1997 | 5-60 | EI: Southwestern Australia | |
| A. bassensis Norman, 1926 | 10-70 | EI, WP: South Australia to New South Wales, Australia | |
| A. aspilos (Bleeker, 1851) | 30-71 | EI, WP: Persian Gulf east to Philippines and New Guinea | |
| A. waitei Norman, 1926 | 16-90 | EI, WP: Arafura Sea and Queensland (Australia) | |
| A. macrolophus Alcock, 1889 | 18-141 | RS, WI, EI: Central Red Sea, Persian Gulf and Madagascar east to Indonesia | Recorded from Eritrea, Red Sea by Dor (1970) as A. tapeinosoma (non Bleeker 1865) |
| A. tenuis Günther, 1880 | 80-100 | EI, WP: Northern Australia to southern Japan | |
| A. muelleri (Klunzinger, 1872) | 5-200 | EI, WP: Southwestern to southeastern Australia | |
| A. blachei Stauch, 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260. | 34-175 | EA: Guinea-Bissau south to Angola | Revalidated in the present paper; previously synonymized with A. imperialis |
| A. japonicus Hubbs, 1915 | 85-154 | EI, WP: Southern Japan to northern Australia | |
| A. laterna (Walbaum, 1792) | 45-200 | EA, MS: Mediterranean and Black seas; eastern Atlantic from Norway to Angola | |
| A. dalgleishi (von Bonde, 1922) | 50-220 | WI, EI, WP: South and East Africa east to Loyalty Islands | |
| A. capensis Boulenger, 1898 | 70-200 | EA, WI: Morocco to South Africa, Saint Helena and Ascension Is. | Synonym: A. entomorhynchus Stauch, 1967 |
| A. arabicus Norman, 1939 | 83-220 | RS, WI: southern Red Sea and northwestern Indian Ocean | |
| A. thori Kyle, 1913 Kyle H.M. 1913. Flat-fishes (Heterosomata). Report on the Danish Oceanographical Expeditions 1908-10 to the Mediterranean and Adjacent Seas, 2 (Biology), A, Dana Rep. 1: 1-150, pls. 1-4. | 5-300 | EA, MS: Mediterranean and Black seas, and eastern Atlantic from Ireland to Sierra Leone | Synonym: A. moltonii Torchio, 1961 |
| A. elongatus Weber, 1913 | 100-224 | EI, WP: Taiwan to Indonesia and northwestern Australia | |
| A. kotthausi Klausewitz and Schneider, 1986 | 138-225 | WI: northwestern Indian Ocean | Synonym: A. profundus Kotthaus, 1977, preoccupied by A. profundus Weber, 1913 |
| A. imperialis ( Rafinesque, 1810 Rafinesque C.S. 1810a. Caratteri di alcuni nuovi generi e nuove specie di animali e piante della Sicilia, con varie osservazioni sopra i medesimi. Sanfilippo, Palermo: Part 1, pp. [i-iv] 3-69 [70 blank]; Part 2 with slightly different title, pp. ia-iva + 71-105 [106 blank]; pls. 1-20.) | 15-350 | EA, MS: western Mediterranean and eastern Atlantic from Scotland to northern Mauritania, including Azores and Madeira | |
| A. sayaensis Amaoka and Imamura, 1990 | 125-254 | WI: Saya de Malha Bank and Madagascar | |
| A. polyspilus (Günther, 1880) | 4-390 | EI, WP: India east to New Caledonia, north to Japan | |
| A. multirastris Parin, 1983 | 160-265 | EP: Nazca Ridge | |
| A. oxyrhynchus Amaoka, 1969 Amaoka K. 1969. Studies on the sinistral flounders found in the waters around Japan: taxonomy, anatomy and phylogeny. J. Shimonoseki Univ. Fish. 18: 65-340. | 215 | WP: Japan; Chesterfield Islands | |
| A. brunneus (Fowler, 1934) | 187-292 | WP: Philippines to Vanuatu | |
| A. septemventralis Amaoka and Mihara, 2000 | 240-250 | WP: New Caledonia | |
| A. nigrifrons Amaoka and Mihara, 2000 | 300 | WP: Chesterfield Islands | |
| A. debilis (Gilbert, 1905) | 150-440 | WP: Indonesia east to Hawaiian and Line Islands | |
| A. scapha (Forster, 1801) | 4-737 | WP: New Zealand | Junior synonym: Pseudorhombus boops Hector, 1875 |
| A. marisrubri Klausewitz and Schneider, 1986 | 363-383 | RS: Central Red Sea | |
| A. rueppelii (Cocco, 1844) | 85-897 | EA, MS: Mediterranean Sea and eastern Atlantic from Gibraltar to western Sahara | |
| A. armstrongi Scott, 1975 | ? | EI: Tasmania, Australia | |
| A. tapeinosoma (Bleeker, 1865) | ? | EI, WP: Sumatra (Indonesia), China |
While examining the catch of R/V Vizconde de Eza during the BISSAU 1219 cruise in Guinea-Bissau, one of the authors (F.O.) discovered numerous specimens of an unusual species of Arnoglossus that was first identified as Arnoglossus imperialis (non Rafinesque 1810) but subsequently found to be different. We determined the valid name for this species and redescribe it in the present paper as Arnoglossus blachei Stauch 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260..
MATERIALS AND METHODS
⌅Morphological descriptions. Counts and measurements follow Hubbs and Lagler (1947) Hubbs C.L., Lagler K.F. 1947. Fishes of the Great Lakes Region. Bulletin Cranbrook Institute of Science (Bloomfield Hills, Michigan) 26: vi+186 pp., descriptive methods follow Arai and Amaoka (1996) Arai M., Amaoka K. 1996. Arnoglossus macrolophus Alcock (Pleuronectiformes: Bothidae); a valid species distinct from A. tapeinosomus (Bleeker). Ichth. Res. 43: 359-365. https://doi.org/10.1007/BF02347635 except for the caudal fin ray formula that follows Fricke (1983) Fricke R. 1983. A method of counting caudal fin rays of actinopterygian fishes. Braunschw. Naturk. Schr. 1: 729-733.; the classification follows Fricke et al. (2022b), references according to Fricke (2022) Fricke R. 2022. References in Eschmeyer’s catalog of fishes, electronic version (6 June 2022). Internet publication, San Francisco (California Academy of Sciences). http://research.calacademy.org/research/Ichthyology/Catalog/fishcatmain.asp . In the description, the data of the lectotype/neotype of the primary name are given first, followed by those of the primary types of synonyms (in the case of Arnoglossus imperialis, the neotype of Rhombus cristatus Lowe, 1839 Lowe R.T. 1839. A supplement to a synopsis of the fishes of Madeira. Proceedings of the Zoological Society of London 1839: 76-92. https://doi.org/10.1111/j.1096-3642.1839.tb01431.x ) in round brackets, and those of other specimens in square brackets. The distribution map was created using QGIS 3.26.1.
Comparative material. Arnoglossus arabicus: HUJ 13300 (9, 43.7-84.2 mm SL), Red Sea, Eritrea, 14°18’N 41°38’E; USNM 109488 (1), Yemen. Arnoglossus capensis: CFM_IEOMA 5258b (1), Morocco; MNHN 1967-0506 (8), Liberia; SMNS 25264 (1), São Tomé and Principe, São Tomé Island. Arnoglossus dalgleishi: MNHN 2014-2211 (2), New Caledonia, Chesterfield Islands; SMNS 23571 (1), Loyalty Islands, Lifou. Arnoglossus grohmanni (formerly known as A. kessleri): HUJ 13310 (7), Israel, Haifa; HUJ 17039 (1), Israel, Jaffa; HUJ 18627 (1), Israel, Zikim Beach; SMNS 11325 (4), Croatia, Cres Island; SMNS 11532 (1), Turkey, Muğla Province; SMNS 12416 (1), Balearic Islands, Formentera; SMNS 15734 (1), Greece, Chalkidiki; SMNS 16088 (1), Croatia, Cres Island; SMNS 16713 (1), Croatia, Cres Island; SMNS 19095 (1), Northern Cyprus, 9 km west Girne; SMNS 24486 (1), Croatia, Cres Island. Arnoglossus laterna: HUJ 232 (1), Israel, Mediterranean coast; HUJ 6575 (3), Israel, Mediterranean coast; HUJ 6598 (2), Egypt, northern Sinai, Wadi Hesi; HUJ 6609 (1), Egypt, Bardawil, Katib el Galss; HUJ 7128 (4), Egypt, Bardawil; HUJ 8494 (1), Cyprus, Akrotiri; HUJ 8501 (2), Cyprus, Famagusta; HUJ 10947 (1), Israel, Tel-Aviv; HUJ 11333 (2), Israel, Ashdod; HUJ 12135 (6), Israel, Haifa; HUJ 13192 (6), Cyprus, Famagusta; HUJ 13205 (4), Israel, Mediterranean coast; HUJ 13246 (3), Israel, Rubin; HUJ 13247 (3), Israel, Rubin; HUJ 13295 (1), Cyprus, Famagusta; HUJ 13302 (4), Israel, Haifa; HUJ 13308 (1), Israel, Rubin; HUJ 13309 (1), Israel, Haifa; HUJ 13329 (2), Gaza Strip and Egypt, Gaza to Al Arish; HUJ 13332 (3), Israel, Rubin; HUJ 13333 (1), Israel, Kishon; HUJ 13676 (1), Cyprus, southeast of Paphos; HUJ 13677 (1), Cyprus, Famagusta; HUJ 13695 (1), Cyprus, southeast coast; HUJ 13827 (1), Israel, Jaffa; HUJ 13963 (3), Israel, Mediterranean coast; HUJ 13980 (1), Egypt, Bardawil, Katib el Galss; HUJ 13981 (2), Israel, Rubin; HUJ 13996 (1), Israel, Haifa; HUJ 17906 (2), Spain, Malaga; HUJ 20081 (2), Israel, Jaffa; SMNS 8761 (30), Italy, Santa Margherita Ligure; SMNS 9237 (1), Balearic Islands, Mallorca; SMNS 14981 (1), Turkey, Sea of Marmara; SMNS 20571 (4), Italy, Venice; SMNS 20571 (1), Italy, Venice. Arnoglossus macrolophus: HUJ 5147 (4), Eritrea; HUJ 13334 (7), Eritrea, Massawa; HUJ 20666 (4), Eritrea; MNHN 2014-1160 (3), Madagascar; MNHN 2014-1690 (3), Madagascar; MNHN 2014-2009 (1), Madagascar; MNHN 2014-2149 (4), Madagascar; SMNHTAU P.2062 (1), Israel, Eilat. Arnoglossus nigrofilamentosus: HUJ 20663 (holotype), Israel, off Jaffa; HUJ 20664 (3 paratypes), Israel, off Jaffa. Arnoglossus rueppelii: HUJ 13689 (1), Israel, Haifa; HUJ 13692 (1), Gaza Strip to Egypt, Gaza to El Arish; HUJ 13693 (1), Gaza Strip, Chan Yunis; HUJ 16099 (5), Israel, Hadera to Herzliya; HUJ 16508 (1), Israel, Ashdod; HUJ 16586 (3), Israel, Ashdod; HUJ 19066 (1), Israel, Haifa; SMNS 24438 (1), Madeira Region, Seine Seamount. Arnoglossus sayaensis: MNHN 2014-1625 (1), Madagascar; MNHN 2014-2189 (1), Madagascar; USNM 307494 (1), Saya de Malha Bank. Arnoglossus thori: HUJ 13202 (1), Israel, Mediterranean coast; HUJ 13240 (1), Cyprus, Famagusta; HUJ 13303 (1), Cyprus, Famagusta; HUJ 13322 (1), Cyprus, Famagusta; HUJ 13439 (2), Cyprus, Famagusta; HUJ 13678 (1), Israel, Tel-Aviv to Herzliya; HUJ 13709 (1), Israel, Haifa; HUJ 13938 (5), Israel, Hadera; HUJ 13986 (2), Israel, Haifa; HUJ 14058 (11), Israel, Caesarea; HUJ 18337 (1), Greece, Crete Island, Heraklion; HUJ 20601 (1), Balearic Islands, northwest of Mallorca, 63-64 m depth; HUJ 20610 (5), Balearic Islands, 111-109 m depth; HUJ 20612 (1), Balearic Islands, north of Mallorca, 65 m depth; HUJ 20622 (1), Balearic Islands, southsoutheast of Mallorca; HUJ 20665 (1), Israel, Jaffa; SMNS 9856 (4), Greece, Varkisa; SMNS 11587 (4), Greece, Varkisa; SMNS 15577 (1), Croatia, Cres Island; SMNS 16087 (1), Croatia, Cres Island.
Genetic analyses. A piece of the right pectoral fin was removed from fresh specimens and preserved in 96% ethanol. A total of 19 samples were used for molecular analyses including specimens of A. blachei (3) and A. capensis (3) collected in Guinea-Bissau during the BISSAU1219 survey, and A. imperialis (5), A. laterna (3), A. rueppelli (2), and A. thori (2) collected during the MEDITS survey in the Balearic Islands in 2020 ( Table 2 ).
| Species | Sample ID | Deep | Latitude | Longitude | Area | COI | 12S |
|---|---|---|---|---|---|---|---|
| A. blachei | ArAF77 | 118 | 10.5788 | 17.0778 | Atlantic | OP341515 | OP345057 |
| A. blachei | ArAF77b | 118 | 10.5788 | 17.0778 | Atlantic | OP341516 | OP345058 |
| A. blachei | ArAF77c | 118 | 10.5788 | 17.0778 | Atlantic | OP341517 | OP345059 |
| A. capensis | ArcaM77 | 118 | 10.5788 | 17.0778 | Atlantic | OP341523 | OP345065 |
| A. capensis | Arca77b | 118 | 10.5788 | 17.0778 | Atlantic | OP341524 | OP345066 |
| A. capensis | Arca77a | 118 | 10.5788 | 17.0778 | Atlantic | OP341525 | OP345067 |
| A. imperialis | Aglm76 | 131 | 39.7978 | 4.4397 | Mediterranean | OP341518 | OP345060 |
| A. imperialis | AgIm76_2 | 131 | 39.7978 | 4.4397 | Mediterranean | OP341519 | OP345061 |
| A. imperialis | AgIm76_3 | 131 | 39.7978 | 4.4397 | Mediterranean | OP341520 | OP345062 |
| A. imperialis | AgIm76 | 131 | 39.7978 | 4.4397 | Mediterranean | OP341521 | OP345063 |
| A. imperialis | AgIm76_4 | 131 | 39.7978 | 4.4397 | Mediterranean | OP341522 | OP345064 |
| A. laterna | Agla11 | 61 | 40.3105 | 0.608 | Mediterranean | OP341526 | OP345068 |
| A. laterna | Agla11_2 | 61 | 40.3105 | 0.608 | Mediterranean | OP341527 | OP345069 |
| A. laterna | Agla71 | 112 | 39.9335 | 3.3058 | Mediterranean | OP341528 | OP345070 |
| A. rueppelii | AgRo73 | 276 | 40.1917 | 4.1132 | Mediterranean | OP341532 | OP345074 |
| A. rueppelii | AgRo73_2 | 276 | 40.1917 | 4.1132 | Mediterranean | OP341533 | OP345075 |
| A. thori | Agth5 | 95 | 39.8313 | 0.7073 | Mediterranean | OP341529 | OP345071 |
| A. thori | Agth5_2 | 95 | 39.8313 | 0.7073 | Mediterranean | OP341530 | OP345072 |
DNA was extracted from the tissue using the DNeasy Blood and Tissue Extraction kit (Qiagen, West Sussex, UK). Polymerase chain reaction (PCR) was used to amplify two partial mitochondrial genes (mtDNA): 12s rRNA with primers 12SL1091/12SH1478 ( Kocher et al. 1989 Kocher T.D., Thomas W.K., Meyer A., et al. 1989. Dynamics of mitochondrial DNA evolution in animals: amplification and sequencing with conserved primers. Proc. Nat. Acad. Sci. 86: 6196-6200. https://doi.org/10.1073/pnas.86.16.6196 ) and the cytochrome c oxidase subunit I (COI; DNA barcode) with primers FF2d / FR1d ( Ivanova et al. 2007 Ivanova N.V., Zemlak T.S., Hanner R., Hebert P.D.N. 2007. Universal primer cocktails for fish DNA barcoding. Molec. Ecol. Notes 7: 544-548. https://doi.org/10.1111/j.1471-8286.2007.01748.x ). PCR was performed in 25 μl volume: 17.7μl ddH2, 2.5μl Mangobuffer (Bioline), 1 μl DNTPs, 1.75 μl MgCl2, 0.5 μl each primer (each 10 pmol), 0.05 μl TAQ (Bioline) and 1 μl DNA. The PCR thermal profile used for both mitochondrial genes was as follows: initial stage of 96°C for 5 min; then 35 cycles at 94°C for 60 seconds, 52°C/54°C for 60 seconds and 72°C for 60 seconds, followed by a final extension at 72°C for 10 min. PCR products were purified using the QIAquickR PCR Purification Kit (QIAGEN). Both heavy and light strands were sequenced on an ABI 3130 sequencer (Applied Biosystems).
Sequences were imported into BioEdit 7.0.5.2. ( Hall 1999 Hall T.A. 1999. BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp. Ser. 41: 95-98.) and checked for quality and accuracy with nucleotide base assignment. Multiple sequence alignments were obtained with ClustalW ( Thompson et al. 1994 Thompson J.D., Higgins D.G., Gibson T.J. 1994. CLUSTAL W: Improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucl. Acids Res. 22: 4673-4680. https://doi.org/10.1093/nar/22.22.4673 ). The DNA sequences obtained for two mitochondrial fragments were deposited in the GenBank database ( http://www.ncbi.nlm.nih.gov/genbank/ ) under the following numbers: OP341515-31 and OP345057-OP345073.
Genetic distance (p-distance) and number of base differences between pairs of sequences of each mitochondrial fragment were calculated with MEGA v.7.1 ( Tamura et al. 2013 Tamura K., Stecher G., Peterson D., et al. 2013. MEGA6: Molecular Evolutionary Genetics Analysis Version 6.0. Molec. Biol. Evolu. 30: 2725-2729. https://doi.org/10.1093/molbev/mst197 ). The average values of both genetic indices between our study sample sequences were compared.
The sequences were concatenated and used to determine the phylogenetic relationships between the Arnoglossus species. To do so, a phylogenetic tree based on Bayesian inference was reconstructed. The optimal substitution model of molecular evolution was the Kimura 2-parameter ( Kimura 1980 Kimura M. 1980. A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J. Molec. Evol. 16: 111-120. https://doi.org/10.1007/BF01731581 ) plus gamma. This model was selected following the Bayesian inference criterion using MEGA. Bayesian inference was performed with MrBayes v.3.2.1 ( Ronquist et al. 2012 Ronquist F., Teslenko M., Van Der Mark P., et al. 2012. Mrbayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 61 (3): 539-542. https://doi.org/10.1093/sysbio/sys029 ) by conducting four independent MCMC runs (with four chains each) for 10 million generations, sampling every 2000 generations and discarding the first 25% of samples as burn-in. This scheme was applied for all the fragments. Convergence was assessed by effective sample size calculation and was visualized using TRACERv.1.5. Arnoglossus tenuis was included as an outgroup for the phylogenetic analysis (GenBank ID for the complete mitochondrial DNA genome: NC044494; Li et al. 2015 Li D.H., Shi W., Munroe T.A., et al. 2015. Concerted evolution of duplicate control regions in the mitochondria of species of the flatfish family Bothidae (Teleostei: Pleuronectiformes). PLoS ONE 10(8) (e0134580): 1-13. https://doi.org/10.1371/journal.pone.0134580 ).
TAXONOMY
⌅Arnoglossus blachei Stauch, 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260.
⌅Blache’s flounder
⌅( Figs 1-4Figs. 1, 2, 3, 4 , Table 3 )
Arnoglossus imperialis (non Rafinesque 1810): Chabanaud and Monod 1927 Chabanaud P, Monod T. 1927. Les poissons de Port-Etienne. Bull. Com. Études Hist. Sci. Afr. Occid. Fr., Paris 9: 225-287.: (Port Etienne/Nouadhibou, Mauritania). Norman 1930 Norman J.R. 1930. Oceanic fishes and flatfishes collected in 1925-1927. Discovery Rep. 2: 261-369, pl. 2.: 360 (Angola; Gabon). Chabanaud 1931a Chabanaud P. 1931a. Sur la ceinture et quelques autres éléments morphologiques des poissons hétérosomates, importance phylogénétique des caractères observés. Bull. Soc. Zool. Fr. 56: 386-398.: 392 (Morocco). Chabanaud 1931b Chabanaud P. 1931b. Les poissons pleuronectes de la Méditerranée (Pisces Heterosomata). Mém. 2, Suppl. ‘Riviera Scientifique’ 1931: 1-40 + 1 unpaginated.: 19 (part: Atlantic). Chabanaud 1933 Chabanaud P. 1933. Poissons hétérosomes recueillis par M. le Professeur A. Gruvel et par MM. R.-Ph. Dollfus et J. Liouville sur la côte atlantique du Maroc. Mém. Soc. Sci. Nat. Maroc 35: 1-111, pls. 1-2.: 41 (Morocco). Norman 1934 Norman J.R. 1934. A systematic monograph of the flatfishes (Heterosomata). Volume 1. Psettodidae, Bothidae, Pleuronectidae. British Museum (Natural History): viii + 459 pp. https://doi.org/10.5962/bhl.title.8585 : 181 (part: Morocco; Angola; Gabon). Fowler 1936 Fowler H.W. 1936. The marine fishes of West Africa based on the collection of the American Museum Congo expedition, 1909-1915. Part II. Bull. Amer. Mus. Nat. Hist. 70: 607-1493.: 1258 (part). Cadenat 1937 Cadenat J. 1937. Recherches systématiques sur les poissons littoraux de la côte occidentale d’Afrique. Liste des poissons littoraux récoltés par le navire “Président Théodore-Tissier” au cours de sa cinquième croisière (1936). Rev. Trav. Inst. Pêches Marit. 10 (4, 40): 425-562.: 519 (southern Morocco; Mauritania). Cadenat 1951 Cadenat J. 1951. Initiations Africaines. III. Poissons de mer du Sénégal. Institut Français d’Afrique Noire, Dakar (for 1950): 1-345.: 141, 299, 315 (Mauritania to Senegal). Cadenat 1953 Cadenat J. 1953. Notes d’ichtyologie ouest africaine. VI. Poissons des campagnes du “Gérard Tréca.” Bull. Inst. Fr. Afr. Noire 15: 1051-1102.: 1073 (Port Etienne/Nouadhibou, Mauritania). Cadenat 1954 Cadenat J. 1954. Note d’ichtyologie ouest africaine. VII. Biologie. Régime alimentaire. Bull. Inst. Fr. Afr. Noire 16: 564-583.: 566 (alimentation). Collignon et al. 1957 Collignon J., Rossignol M., Roux C. 1957. Mollusques, crustacés, poissons marins des côtes d’A.E.F. en collection au Centre d’Océanographie de l’Institut d’Études Centafricaines de Pointe-Noire. Office de la Recherche Scientifique et technique Outre-Mer, Paris: 1-369.: 232 (Mauritania). Roux 1957 Roux C. 1957. Pisces. pp. 137-369. In: Collignon, J., Rossignol, M., Roux, C. 1957. Mollusques, crustacés, poissons marins des côtes d’A.E.F.: en collection au Centre d’Océanographie de l’Institut d’études centrafricaines de Pointe-Noire. Part 1. Office de la recherche scientifique et technique Outre-Mer, Paris: 369 pp.: 232. Poll 1959 Poll M. 1959. Poissons V. -- Téléostéens acanthoptérygiens (deuxième partie). Résultats Scientifiques. Expédition Océanographique Belge dans les Eaux Côtières Africaines de l’Atlantique Sud (1948-1949), Bruxelles 4 (3B): 1-417, pls. 1-7, 1 tab.: 312 (Congo). Postel 1959 Postel E. 1959. Liste commentée des poissons signalés dans l’Atlantique tropico-oriental nord, du Cap Spartel au Cap Roxo, suivie d’un bref aperçu sur leur répartition bathymétrique et géographique. Bull. Soc. Sci. Bretagne 34: 129-170.: 167. Cadenat 1960 Cadenat J. 1960. Notes d’ichtyologie ouest-africaine. XXX. Poissons de mer ouest-africains observés du Sénégal au Cameroun et plus spécialement au large des côtes de Sierra-Leone et du Ghana. Bull. Inst. Fr. Afr. Noire (Sér. A) Sci. Nat. 22: 1358-1423, 3 pls.: 1379 (Sierra Leone, Gambia, Senegal). Bassindale 1961 Bassindale R. 1961. On the marine fish fauna of Ghana. Proc. Zool. Soc. London 137: 481-510. https://doi.org/10.1111/j.1469-7998.1961.tb06086.x : 508 (Ghana). Nielsen 1961 Nielsen J.G. 1961. Psettodoidea and Pleuronectoidea (Pisces, Heterosomata). Atlantide Rep. 6: 101-127, pl. 2.: 113, pl. 2, fig. C (Guinea-Bissau to Ivory Coast). Blache 1962 Blache J. 1962. Liste des poissons signalés dans l’Atlantique tropico-oriental sud du Cap des Palmes (4°Lat.N.) à Mossamedes (15°Lat.S.) (province Guineo-Equatoriale). Trav. Lab. Océanogr., Biol. Div. 1962: 14-102.: 76. Sanches 1966 Sanches J.G. 1966. Peixes de Angola (Teleosteos). Not. Mimeogr. Cent. Biol. Piscat. 46: i-iii + 1-227.: 17 (Angola). Maurin 1968 Maurin C. 1968. Écologe ichthyologique des fonds chalutables atlantiques (de la baie Ibéro-Marocaine à la Mauritanie) et la Méditerranéee occidentale. Rev. Trav. Inst. Pêch. Marit. 32: 5-147.: 48, 62 (Mauritania). Williams 1968 Williams F. 1968. Report on the Guinean trawling survey. I. General Report. Lagos: ix + 828 pp.: 817 (Guinea). Troadec et al. 1969 Troadec J.P., Barro M., Bouillon P. 1969. Pêches au chalut sur la radiale de Grand Bassam (Côte d’Ivoire) (Mars 1966 - Février 1967). Documents Scientifiques Provisoires du Centre de Recherche Océanographique, Abidjan 33: 1-14, 86 pls. (Mimeographed).: tabs. 8-10 (Ivory Coast). Aldebert 1970 Aldebert Y. 1970. Répartition bathymétrique et géographique des poissons hétérosomes récoltés par la “Thalassa” en 1962 au Rio de Oro et en Mauritanie. Rapp. Proc.-Verb. Réunion Perm. Int. Explor. Mer 159: 213-217.: 215 (Mauritania). Maurin et al. 1970 Maurin C., Lozano Cabo F., Bonnet M. 1970. Inventaire faunistique des principales espèces ichtyologiques fréquentant les côtes nord-ouest africaines. Rapp. Proc.-Verb. Réun. Perm. Int. Explor. Mer 159: 15-21.: 20 (Morocco). Groot and Nijssen 1971 Groot S.J. de, Nijssen H. 1971. Notes on the fishes collected by the R.V. “Tridens” on the North West African shelf, 19-25 January 1969. Bijdr. Dierk. 41: 3-9. https://doi.org/10.1163/26660644-04101001 : 8 (Mauritania). Aboussouan 1972 Aboussouan A. 1972. Oeufs et larves de téléostéens de l’ouest africain. XII. Les larves d’Heterosomata récoltés aux environs de l’île Gorée (Sénégal). Bull. Inst. Fondam. Afrique Noire (A) 34 (4): 974-1003.: 999 (Senegal). Bravo de Laguna and Santaella Álvarez 1973 Bravo de Laguna C.J., Santaella Álvarez E. 1973. Observaciones biológico-pesqueras en el banco pesquero sahariano. Bol. Inst. Esp. Oceanogr. 171: 1-79.: 21, 74 (western Sahara). Bas et al. 1976 Bas C., Arias A., Guerra A. 1976. Peces efectuados duranta la campaña “Atlor V” (C. Bojador - C. Blanco, abril-mayo 1974). Características y tratamiento de las capturas. Res. Exped. Cient. Buque Oceanogr. “Cornide de Saaveedra” 5: 161-172.: tab. 3 (western Sahara). Maul 1976 Maul G.E. 1976. The fishes taken in bottom trawls by R.V. “Meteor” during the 1967 Seamounts Cruises in the Northeast Atlantic. “Meteor” Forschungserg. D 22: 1-69.: 61 (part: Morocco). Lleonart i Alberas 1979 Lleonart i Alberas J. 1979. La comunitat epibentònica del banc Canari-Saharià, tipificació i cartografia mitjançant l’anàlisi de dades i comentaris crítics sobre la metodologia. PhD Dissertation, Universtat de Barcelona: 1-457.: 136 (western Sahara). Nielsen in Whitehead et al. 1986 Whitehead P.J.P., Bauchot M.-L., Hureau J.-C., et al. 1986. Fishes of the North-eastern Atlantic and the Mediterranean. Volume 3. UNESCO, Paris: 1015-1473. https://doi.org/10.2307/1444931 : 1294 (part). Lloris and Rucabado 1979 Lloris D., Rucabado J.A. 1979. Especies ictiológicas de las expediciones pesqueras realizadas en la plataforma del NW de Africa (1971-1975). Res. Expedi. Cient. B/O Cornide de Saavedra 8: 3-151.: 21, 129 (western Sahara). Gutherz and Quéro 1981 Gutherz E.J., Quéro J.-C. 1981. Bothidae. 26 pp. In: Fischer, W., Bianchi, G. Scott, W.B. (eds): FAO Species Identification Sheets for Fishery Purposes. Eastern Central Atlantic, Fishing areas 34, 47 (in part). FAO and Department of Fisheries and Oceans Canada, Ottawa.: BOTH Arno 3, 2 pp. (eastern-central Alantic). González and Hernández 1987 González J.A., Hernández C.M. 1987. Catálogo de las especies del orden Heterosomata (Pleuronectiformes, Osteichthyes) en Canarias. Vieraea 17: 155-170.: 159 (Tenerife, Canary Islands). Aldebert et al. 1990 Aldebert Y., Desoutter M., Quéro J.-C. 1990. Bothidae. pp. 1027-1036. In: Quéro, J.-C., Hureau, J.-C., Karrer, C., Post, A., Saldanha, L. (ed): Check-list of the fishes of the eastern tropical Atlantic. CLOFETA. Volume 3. UNESCO, Paris: 1081-1492.: 1028 (with question). Lloris et al. 1991 Lloris D., Rucabado J., Figueroa H. 1991. Biogeography of the Macaronesian ichthyofauna (the Azores, Madeira, the Canaryu islands, Cape Verde and the African enclave). Bol. Mus. Municip. Funchal 43 (234): 191-241.: 221 (part: Canary Islands; Africa). Bianchi and Carpenter in Bianchi et al. 1993 Bianchi G., Carpenter K.E., Roux J.-P., et al. 1993. FAO Species Identification Field Guide for Fisheries Purposes. The Living Marine Resources of Namibia. FAO, Rome: i-viii + 1-250, pls. 1-7.: 178 (Namibia). Lalithambik Devi and Stephen 1998 Lalithambik Devi C.B., Stephen R. 1998. First record of larvae of Arnoglossus imperialis (Rafinesque, 1810) (Bothidae, Pisces) Atlantic species from the Indian Ocean. IOC Worksh. Rep. 142: 108-113.: 112 (larvae reaching Agulhas Bank, South Africa, Indian Ocean). Desoutter et al. 2001 Desoutter M., Chapleau F., Munroe T.A., et al. 2001. Catalogue critique des types de poissons du Muséum national d’Histoire naturelle (suite). Ordre des Pleuronectiformes. Cybium 25: 299-368.: 302 (MNHN type catalogue). Brito et al. 2002 Brito A., Pascual P.J., Falcón J.M., et al. 2002. Peces de las islas Canarias. Francisco Lemus, Tenerife: 1-419.: 329, fig. 418 (Tenerife, Canary Islands/Spain). Serghini et al. 2008 Serghini M., Boutayeb A., Boumâaz A., et al. 2008. Stability of the spatial structures of demersal assemblage in the Moroccan southern Atlantic zone. Appl. Ecol. Env. Res. 6: 117-127. https://doi.org/10.15666/aeer/0601_117127 : 119 (southern Morocco). Munroe in Carpenter and De Angelis 2016 Carpenter K.E., De Angelis N. (eds) 2016. The living marine resources of the Eastern Central Atlantic. Volume 4. Bony fishes part 2 (Perciformes to Tetraodontiformes) and Sea turtles. FAO Species Identification Guide for Fishery Purposes. Rome, FAO.: 2981. Fricke et al. 2017 Fricke R., Golani D., Appelbaum-Golani B. 2017. Arnoglossus nigrofilamentosus n. sp., a new species of flounder (Teleostei: Bothidae) from off the Mediterranean coast of Israel, probably a new case of Lessepsian migration. Sci. Mar. 81: 257-265. https://doi.org/10.3989/scimar.04684.07A : 3. Reiner 2019 Reiner F. 2019. Peixes do arquipélago de São Tomé e Príncipe, Golfo da Guiné (Oceano Atlântico Oriental). Projecto Delfin. Centro Português de Estudo dos Mamíferos Marinhos, Lisboa: 1-332, index, 12 pls.: 290 (São Tomé and Principe). Amaoka et al. 2020 Amaoka K., Matsuura K., Carpenter K.E., Munroe TA 2020. Arnoglossus imperialis. IUCN Red List Threatened Spec. 2020, e.T154687A15522283: 1-10.: 4 (part: eastern Atlantic). Fermon et al. 2022 Fermon Y., Bailly N., Cardiec F., et al. 2022. An annotated checklist of the fishes of Gabon. Cybium 46: 69-317.: 230 (Gabon).
Arnoglossus blachei Stauch 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260.: 256, fig. 7 (Angola, 13°31’36’’S, 12°19’36’’E; Cameroon, 3°40’1.2’’N, 9°13’1.2’’E, 34 m depth). Williams 1968 Williams F. 1968. Report on the Guinean trawling survey. I. General Report. Lagos: ix + 828 pp.: 342 (Guinea). Blache et al. 1970 Blache J., Cadenat J., Stauch A. 1970. Clés de détermination des poissons de mer signalés dans l’Atlantique oriental (entre le 20e parallele N. et le 15e parallele S.). Faune Tropicale XVIII. Office de la Recherche Scientifique et Technique Outre-Mer, Paris: 1-479.: 425 (West Africa). Bas 1974 Bas C. 1974. Distribución de especies demersales recogidas durante la expedición oceanográfica “Sahara I”. Res. Exped. Cient. B/O “Cornide” 3: 187-247.: 193, 196, 235 (western Sahara). Lloris and Rucabado 1979 Lloris D., Rucabado J.A. 1979. Especies ictiológicas de las expediciones pesqueras realizadas en la plataforma del NW de Africa (1971-1975). Res. Expedi. Cient. B/O Cornide de Saavedra 8: 3-151.: 22, 131 (western Sahara). Sobrino Yraola and García Jiménez 1997 Sobrino Yraola I., García Jiménez T. 1997. Análisis de los descartes producidos por la flota Española en la pesquería de crustáceos decápodos en aguas de la República Islámica de Mauritania. Inform. Técn., Inst. Esp. Oceanogr. 166: 1-24.: 14 (Mauritania).
Lectotype of Arnoglossus blachei Stauch 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260. (designated herein) : BMNH 1930.5.6.36, one male, 73.7 mm SL, Gabon, 27.2 km west of Cap Lopez, 0°36’S 8°28’E, 64-65 m depth, RRS Discovery, 10 Aug. 1927.
Paralectotypes of Arnoglossus blachei: BMNH 1930.5.6.34 (one female), 66.7 mm SL, Angola, Elephant Bay, 13°31’36’’S 12°19’36’’E, 73-97 m depth, RRS Discovery, 28 July 1927. BMNH 1930.5.6.35 (one female), 62.0 mm SL, Angola, off Luanda, 08°40’15’’S 13°13’45’E, 64-65 m depth, RRS Discovery, 4 Aug. 1927.
Other material: CFM_IEOMA 2102 (2), Mauritania, northwest of El-Mamghar, 19°50’24’’N 17°17’24’’W, 108 m depth; CFM_IEOMA 2832 (2), Mauritania, northwest of El-Mamghar, 20°10’12’’N 17°36’36’’W, 112 m depth; CFM_IEOMA 2838 (2), Mauritania, northwest of El-Mamghar, 19°40’12’’N 17°04’12’’W, 158 m depth; CFM_IEOMA 5258a (1), western Sahara, north to Dakhla, 24°33’36’’N 16°09’36’’W, 239 m depth; CFM_IEOMA 7767 (5), Guinea-Bissau, 11°27’43.2’’N 17°11’06’’W - 11°28’37.2’’N 17°11’16.8’’W, 103-105 m depth; CFM_IEOMA 7768 (2), Guinea-Bissau, 10°10’18.48’’N 16°34’26.4’’W, 207-206 m depth; CFM_IEOMA 7766 (3), Guinea-Bissau, 10°34’44.4’’N 17°04’40.8’’W 10°33’54’’N 17°04’19.2’’W, 118-104 m depth; SMNS 27381 (2), Guinea-Bissau; SMNS 27382 (2), Guinea-Bissau; SMNS 27383 (1), Guinea-Bissau.
| Lectotype of Arnoglossus blachei Stauch, 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260., BMNH 1930.5.6.36 (Gabon) | Paralectotypes of Arnoglossus blachei Stauch, 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260.(Angola) | Other material: CFM_IEOMA 2102 (1), 2832 (2), 2838 (2), 7766 (4), 7767 (5), 7768 (2); SMNS 27381 (2), 27382 (2), 27383 (1) | |||
|---|---|---|---|---|---|
| Spec. 1, BMNH 1930.5.6.34 | Spec. 2, BMNH 1930.5.6.35 | ||||
| Sex | Male | Female | Female | Males (n = 11) | Females (n = 9) |
| Dorsal-fin rays | 95 | 94 | 91 | 89-96 | 89-99 |
| Anal-fin rays | 71 | 64 | 69 | 66-75 | 70-77 |
| Pectoral-fin rays (ocular side) | 10 | 10 | 10 | 10-12 | 11 |
| Pectoral-fin rays (blind side) | 9 | 7 | 7 | 9-10 | 9-10 |
| Caudal-fin rays | iii,11,iii | iii,11,iii | iii,11,iii | iii,11,iii (1 specimen: iii,12,ii) | iii,11,iii |
| Lateral-line scales | 55 | 52 | 55 | 53-56 | 53-57 |
| Gill rakers on first arch, lower branch (ocular side) | 6 | 6 | 6 | 5-8 | 6-7 |
| Vertebrae | 10 + 31 | 10 + 30 | 10 + 30 | 10 + 31-33 | 10 + 31-33 |
| SL | 73.7 | 66.7 | 62.0 | 66.7-110.8 | 89.0-107.0 |
| Head length (ocular side) | 24.6 | 26.1 | 26.0 | 23.0-27.8 | 22.9-25.1 |
| Body depth | 39.6 | 42.4 | 41.4 | 39.9-45.6 | 39.7-43.8 |
| Upper orbit diameter | 8.4 | 8.7 | 9.1 | 6.9- 9.6 | 6.5- 8.5 |
| Lower orbit diameter | 8.2 | 8.5 | 9.3 | 6.9- 9.0 | 6.5- 8.3 |
| Interorbital distance | 0.9 | 0.8 | 0.4 | 0.4- 0.7 | 0.3- 0.5 |
| Upper jaw length (ocular side) | 9.4 | 8.4 | 9.6 | 7.0- 8.6 | 7.0- 8.1 |
| Lower jaw length (ocular side) | 6.7 | 6.6 | 7.3 | 5.2- 7.0 | 5.1- 6.1 |
| Lower jaw length (blind side) | 6.9 | 7.2 | 8.3 | 5.2- 6.8 | 5.3- 5.9 |
| Caudal peduncle depth | 9.4 | 11.2 | 10.2 | 8.6-11.3 | 8.8- 9.5 |
| Length of longest dorsal-fin ray | 22.8 | 12.4 | 13.6 | 23.9 -34.7 | 7.3-10.9 |
| Length of longest anal-fin ray | 9.6 | 10.3 | 13.4 | 10.2-12.7 | 10.4-11.5 |
| Pectoral-fin length (ocular side) | 11.4+ | 16.2 | 15.7 | 14.4-17.3 | 15.4-17.5 |
| Pectoral-fin length (blind side) | 6.4 | 6.2 | 6.7 | 7.2- 8.3 | 6.7- 7.1 |
| Pelvic-fin length (ocular side) | 13.9 | 12.7 | 10.3 | 14.2-15.6 | 11.5-16.2 |
| Pelvic-fin length (blind side) | 8.2 | 8.0 | 10.8 | 8.5-11.3 | 8.1-10.5 |
| Length of pelvic-fin base (ocular side) | 7.9 | 6.8 | 6.4 | 7.0- 9.4 | 6.5- 8.8 |
| Length of pelvic-fin base (blind side) | 4.6 | 4.8 | 6.9 | 3.3- 4.5 | 2.4- 4.0 |
| Length of longest caudal-fin ray | 14.2+ | 18.6 | 18.8 | 17.6-20.1 | 17.4-19.5 |
Diagnosis. A species of Arnoglossus with the second to fifth dorsal-fin rays elongate and filamentous in males, dorsal-fin rays 89-99, anal-fin rays 66-77, pectoral-fin rays on ocular side 10-12, on blind side 9-10, caudal-fin rays iii,11,iii , lateral-line scales 52-57, gill rakers 0 + 5-8, not serrated, interorbital a narrow bony ridge without scales in the middle, interorbital width 4% to 17% of upper orbit diameter, no enlarged teeth anteriorly in upper jaw, and prevomer small, not enlarged, weakly projecting into mouth cavity; male body on ocular side rose in life, on blind side bright red; male dorsal-fin filaments grey, bordered black, tips yellow; peritoneum on orbital side black, on blind side silver.
Description. Counts and measurements of the lectotype of Arnoglossus blachei Stauch 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260. and other material listed in Table 3 are part of this description.
Body oval, laterally strongly compressed, eyes on the left side of body (“ocular side”), right side of body without eyes (“blind side”). Body depth 2.5 [2.2-2.5] in SL, 39.6 [39.7-45.6]% of SL. Head length of ocular side 4.1 [3.6-4.4] in SL, 24.6 [22.9-27.8]% of SL. Snout slightly pointed, not completely scaled, tip naked. Anterior teeth in upper jaw not enlarged, prevomer not enlarged, weakly projecting into mouth cavity. Anterior nostril situated anterior to the eyes, posterior nostril on level of anterior margin of eyes. Upper orbit diameter 2.9 [1.7-3.0] in head length, 8.4 [6.5-9.6]% of SL; lower orbit diameter 3.0 [2.1-3.1] in head length, 8.2 [6.5-9.3]% of SL. Interorbital a narrow, low bony ridge, in the middle without scales, interorbital distance 0.9 [0.3-0.8]% of SL. Scales on orbital and blind sides cycloid. Lateral line barely arched over pectoral fin (arch formed by anterior 12-13 scales); lateral-line scales 50 [52-57]. Caudal peduncle depth 10.6 [8.8-11.6] in SL, 9.4 [8.6-11.3]% of SL. Precaudal vertebrae 10 [10], caudal vertebrae 31 [30-33].
Dorsal fin with 94 [89-99] soft rays, the second to fifth rays elongate and filamentous in the male. Anal fin with 73 [66-77] soft rays. Caudal fin distally rounded, caudal fin rays iii,11,iii [iii,11,iii]. Length of longest caudal-fin ray 7.0- [5.0-5.7] in SL, 14.2+ [17.4-20.7]% of SL, damaged in lectotype. Pectoral fin with 10 [10-12] soft rays on ocular side, with 9 [9-10] rays on blind side. Pectoral-fin length 8.7- [5.7-6.6] in SL, 11.4+ [14.4-17.5]% of SL on ocular side, damaged in lectotype, 12.2 [12.0-16.1] in SL, 8.2 [6.2-8.3]% of SL on blind side. Pelvic-fin length 12.6 [6.4-9.7] in SL, 7.9 [10.3-15.6]% of SL on ocular side, 12.2 [8.8-12.5] in SL, 8.2 [8.0-11.3]% of SL on blind side.
Colour of fresh specimens ( Figs 3 , 4 ). Head and body with ocular side yellowish in females, rose in males, with margins of scales dark brown, head and opercle grey; blind side pale in females, bright red in males, head pale, belly white; peritoneum black on eyed side, silvery white on blind side. Dorsal-fin filaments of males light grey, with black margins, distally yellowish; dorsal, anal, pelvic and caudal fins otherwise with a dark grey margin. Pectoral fins on both sides translucent.
Colour in preservative ( Figs 1 , 3 ). Similar to live colouration, but red colours fade to pale yellowish.
Distribution. Eastern Atlantic Ocean (Canary Islands, Morocco, western Sahara, Mauritania, Senegal, Gambia, Guinea-Bissau, Sierra Leone, Ghana, Ivory Coast, Cameroon, Guinea, São Tomé and Principe, Congo, Gabon, Angola, Namibia); southwestern Indian Ocean (larvae reaching Agulhas Bank/South Africa) ( Fig. 5 ). This species has been collected on sand bottoms at 34-175 m depth.
Remarks. Specimens from the eastern Atlantic, previously assigned to Arnoglossus imperialis (non Rafinesque 1810), were found to represent a different species that was previously named A. blachei Stauch 1965. Arnoglossus blachei is revalidated in the present paper. As the species was originally based on several syntypes from various localities off West Africa, the specimen BMNH 1930.5.6.36 (male, 73.7 mm SL, Gabon, 27.2 km west of Cap Lopez, 0°36’S 8°28’E, 64-65 m depth) ( Figs 1 , 2 ) is selected as a lectotype to stabilize the identity of this species, and the nomenclature within this group.
A specimen recorded as Arnoglossus sp. by Wirtz et al. (2007: 41) Wirtz P., Ferreira C.E.L., Floeter S.R., et al. 2007. Coastal fishes of São Tomé and Principe islands, Gulf of Guinea (eastern Atlantic Ocean) - an update. Zootaxa 1523: 1-48. https://doi.org/10.11646/zootaxa.1523.1.1 from São Tomé and Principe was reidentified (SMNS 25264) and turned out to represent a specimen of Arnoglossus capensis Boulenger 1898. Arnoglossus blachei is known neither from São Tomé and Principe nor from the Cape Verde Islands, but occurs on sand bottoms on the southern side of the Canary Islands.
This species is distributed from Morocco and the Canary Islands southward along the coast of West Africa. Populations in the northeastern Atlantic from the Strait of Gibraltar, Madeira and the Azores northward, including the Mediterranean Sea, belong to Arnoglossus imperialis. Apparently, the two species are allopatric. We thus confirm the geographic separation proposed by Stauch (1965) Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260. but provide some more precision for the northern range of A. blachei ( Fig. 5 ).
The bright red colour of the blind side of males of A. blachei is very unusual. This is the only flatfish species we are aware of with such a striking sexual dichromatism. Furthermore, we do not know how the fishes can see the red colour, as they are living below 34 m depth; at this depth red colour is not visible with natural illumination. A plausible explanation would be the presence of bioluminiscence in this species. There might be a luminiscent organ in the belly area, as the peritoneum is black only dorsally, but not ventrally. Luminiscence has apparently been observed by Cornish fishermen in live A. laterna (see Pennant 1776 Pennant T. 1776. British zoology. 4th Edition. London. Volume 3: Class III. Reptiles. Class IV. Fish. Benjamin White, London: 1-425, pls. 1-73.: 233 as “The lantern fish”). So far, we have been unable to locate luminiscent organs in either of these species, or in A. imperialis. The question whether there is bioluminiscence in A. blachei or A. imperialis needs further research.
Arnoglossus imperialis (Rafinesque, 1810)
⌅Imperial flounder
⌅( Figs 6-11Figs. 6, 7, 8, 9, 10, 11 , Table 4 )
Bothus imperialis Rafinesque 1810a Rafinesque C.S. 1810a. Caratteri di alcuni nuovi generi e nuove specie di animali e piante della Sicilia, con varie osservazioni sopra i medesimi. Sanfilippo, Palermo: Part 1, pp. [i-iv] 3-69 [70 blank]; Part 2 with slightly different title, pp. ia-iva + 71-105 [106 blank]; pls. 1-20.: 23 (Sicily, Italy, Mediterranean Sea). Rafinesque 1810b Rafinesque C.S. 1810b. Indice d’ittiologia siciliana; ossia, catalogo metodico dei nomi latini, italiani, e siciliani dei pesci, che si rinvengono in Sicilia disposti secondo un metodo naturale e seguito da un appendice che contiene la descrizione de alcuni nuovi pesci siciliani. G. del Nobolo, Messina: 1-70, pls. 1-2. https://doi.org/10.5962/bhl.title.58965 : 15.
Bothus punctatus Rafinesque 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 : 17 (Sicily Italy, Mediterranean Sea). Parenti 2019 Parenti P. 2019. The status of the fishes described from Sicily by Rafinesque. FishTaxa 4: 99-124.: 108 (questionably a synonym of Arnoglossus imperialis).
Rhombus cristatus Lowe 1839 Lowe R.T. 1839. A supplement to a synopsis of the fishes of Madeira. Proceedings of the Zoological Society of London 1839: 76-92. https://doi.org/10.1111/j.1096-3642.1839.tb01431.x : 88 (Madeira).
Arnoglossus lophotes Günther 1862 Günther A.C.L.G. 1862. Catalogue of the fishes in the British Museum. Catalogue of the Acanthopterygii, Pharyngognathi and Anacanthini in the collection of the British Museum. Volume 4. British Museum, London: i-xxi + 1-534.: 417 (?British coast, Europe). Collett 1896 Collett R. 1896. Poissons provenant des campagnes du Yacht “L‘Hirondelle” (1885-1888). Résultats des campagnes scientifiques accomplies sur son yacht par Albert I, Prince Souverain de Monaco. Rés. Camp. Sci. Prince de Monaco, 10: i-viii + 1-198, pls. 1-6.: 95 (Azores; Gulf of Gascogne, France). Murray and Hjort 1912 Murray J., Hjort J. 1912. The depths of the ocean. MacMillan and Co., London: i-xx + 1-821.: 407. Nobre 1935 Nobre A. 1935. Fauna marinha de Portugal. I - Vertebrados. Porto.: 205 (Portugal).
Arnoglossus grohmanni (non Bonaparte 1837): Day 1882 Day F. 1882. On the identity of Arnoglossus lophotes, Günther, with A. grohmanni. Proc. Zool. Soc. London 1882: 748-750, pl. 53. https://doi.org/10.1111/j.1096-3642.1883.tb02789.x : 748, pl. 53.
Charybdia rhomdoidichthys Facciolà 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.]: 266 (Messina, Sicily, Italy, Mediterranean Sea).
Arnoglossus imperialis: Petersen 1909: Figs 26-29 Petersen C.G.J. 1909. On the larval and postlarval stages of some Pleuronectidae (Zeugopterus, Arnoglossus, Solea). Medd. Komm. Havunders., Ser. Fisk. 3: 1-18, 2 pls.. Kyle 1913 Kyle H.M. 1913. Flat-fishes (Heterosomata). Report on the Danish Oceanographical Expeditions 1908-10 to the Mediterranean and Adjacent Seas, 2 (Biology), A, Dana Rep. 1: 1-150, pls. 1-4.: 79 (English Channel to western Mediterranean). Bertin 1929 Bertin L. 1929. Gasterosteidae, Heterosomata Bothidae. Fiches 372-378. In: Joubin L. (ed): Faune ichtyologique de l’Atlantique Nord. CIEM, Copenhagen.: fiche 378. Chabanaud 1931b Chabanaud P. 1931b. Les poissons pleuronectes de la Méditerranée (Pisces Heterosomata). Mém. 2, Suppl. ‘Riviera Scientifique’ 1931: 1-40 + 1 unpaginated.: 19 (part: English Channel). Bertin 1932 Bertin L. 1932. Les Arnoglossus, poissons Hétérosomes, de la région de Banyuls. Bull. Soc. Zool. France 57: 239-245.: 242 (Banyuls-sur-Mer, France). Norman 1934 Norman J.R. 1934. A systematic monograph of the flatfishes (Heterosomata). Volume 1. Psettodidae, Bothidae, Pleuronectidae. British Museum (Natural History): viii + 459 pp. https://doi.org/10.5962/bhl.title.8585 : 181 (part: Madeira; Europe). Fowler 1936 Fowler H.W. 1936. The marine fishes of West Africa based on the collection of the American Museum Congo expedition, 1909-1915. Part II. Bull. Amer. Mus. Nat. Hist. 70: 607-1493.: 1258 (part). Chabanaud 1939 Chabanaud P. 1939. Catalogue systématique et chorologique des Téléostéens dyssymétriques du Globe. Bull. Inst. Océanogr. (Monaco) 763: 1-31.: 7. Albuquerque 1954-1956 Albuquerque R. M. 1954-1956. Peixes de Portugal e ilhas adjacentes. Chaves para a sua determinação. Portugaliae Acta Biol. 5: i-xvi + 1-1064, i-iii.: 961 (Portugal). Padoa 1956 Padoa E. 1956. Triglidae, Peristediidae, Dactylopteridae, Gobiidae, Echeneidae, Jugulares, Gobiesocidae, Heterosomata, Pediculati. In: Uova, larve e stadi giovanili di Teleostei. Fauna Flora Golfo Napoli 38: 627-888, pls. 39-50.: 800. Bauzá Rullán 1958 Bauzá Rullán J. 1958. Otolitos de peces actuales. Bol. R. Soc. Esp. Hist. Nat. (Biol.) 56: 111-126, pls. 1-4.: 117 (otoliths). Stauch 1965 Stauch A. 1965. Sur la répartition géographique d’Arnoglossus imperialis (Raf. 1810) et description d’une espèce nouvelle, Arnoglossus blachei (Pisces, Teleostei, Heterosomata, Bothidae). Bull. Mus. Nat. Hist. Nat. (Sér. 2) 37: 252-260.: 255 (Ireland and southern England south to Portugal; western Mediterranean Sea). Bini 1968 Bini G. 1968. Atlante dei pesci delle coste itraliane. Tomo 8. Pleuronettiformi, Echeniformi, Gobiesociformi, Tetraodontiformi, Lofiformi. Mondo Sommerso, Milano: 164 pp.: 47 (Italy). Wheeler 1969 Wheeler A.C. 1969. The fishes of the British Isles and North-west Europe. Michigan State University Press, East Lansing, Michigan: i-xvii + 1-613, pls. 1-16.: 530 (western English Channel, southern Ireland). Nielsen 1973 Nielsen J.G. 1973. Bothidae. pp. 620-622. In: Hureau J.-C., Monod T. 1973. Check-list of the Fishes of the North-eastern Atlantic and of the Mediterranean. CLOFNAM. Volume 1. Unesco, Paris: i-xxii + 1-683.: 621. Deniel 1975 Deniel C. 1975. Regimes alimentaires d’Arnoglossus thori Kyle et d’Arnoglossus imperialis Rafinesque. Rev. Trav. Pêch. Marit. 39: 105-116.: 109 (France: alimentation). Maul 1976 Maul G.E. 1976. The fishes taken in bottom trawls by R.V. “Meteor” during the 1967 Seamounts Cruises in the Northeast Atlantic. “Meteor” Forschungserg. D 22: 1-69.: 61 (part: Portugal; Gettysburg Bank; Josephine Bank). Deniel 1983 Deniel C. 1983. La reproduction des poissons plats (Téléostéens- Pleuronectiformes) en Baie de Douarnenez. I. - Cycles sexuels et fécondité des arnoglosses Arnoglossus thori, A. laterna, A. imperialis (Bothidae). Cah. Biol. Mar. 24: 231-252.: 234 (France; reproduction). Nielsen in Whitehead et al. 1986: 1294 (part). Jardas and Pallaoro 1987 Jardas I., Pallaoro A. 1987. A contribution to the knowledge of the ichthyofauna of the Adriatic Sea: Arnoglossus imperialis (Rafinesque, 1810) (Heterosomata, Bothidae) a new species in the Adriatic Sea. Inst. Oceanogr. Ribarst. Split, Bilj. - Notes 69: 1-8.: 2 (Croatia, Adriatic Sea). Aldebert et al. 1990 Aldebert Y., Desoutter M., Quéro J.-C. 1990. Bothidae. pp. 1027-1036. In: Quéro, J.-C., Hureau, J.-C., Karrer, C., Post, A., Saldanha, L. (ed): Check-list of the fishes of the eastern tropical Atlantic. CLOFETA. Volume 3. UNESCO, Paris: 1081-1492.: 1028. Lloris et al. 1991 Lloris D., Rucabado J., Figueroa H. 1991. Biogeography of the Macaronesian ichthyofauna (the Azores, Madeira, the Canaryu islands, Cape Verde and the African enclave). Bol. Mus. Municip. Funchal 43 (234): 191-241.: 221 (part: Azores; Madeira). Wheeler 1992 Wheeler A.C. 1992. A list of common and scientific names of the fishes of the British Isles. J. Fish Biol. 41A: 5-26. https://doi.org/10.1111/j.1095-8649.1992.tb05644.x : 16. Gil de Sola Simarro 1994 Gil de Sola Simarro L. 1994. Ictiofauna demersal de la plataforma continental del mar de Alborán (Mediterráneo suroccidental ibérico). Bol. Inst. Esp. Oceanogr. 10: 63-79.: 67 (Alboran Sea, Spain). Arruda 1997 Arruda L.M. 1997. Checklist of the marine fishes of the Azores. Arq. Mus. Bocage (N. S,) 3 (2): 13-162.: 118 (Azores). Merella et al. 1997 Merella P., Quetglas A., Alemany F., Carbonell A. 1997. Length-weight relationship of fishes and cephalopods from the Balearic Islands (western Mediterranean). Naga, ICLARM Quart., July-December 1997: 66-68.: 67 (Balearic Islands/Spain). Santos et al. 1997 Santo R.S., Porteiro F.M., Barreiros J.P. 1997. Marine fishes of the Azores. An annotated checklist and bibliography. Arquipel. Suppl. 1: i-xxvii + 1-244.: 129 (Azores). Evseenko 1998 Evseenko S.A. 1998. The family Achiropsettidae and its position in taxonomical and ecological classifications of the order Pleuronectiformes. Russian Academy of Science, Moscow: 1-62.: 59. Bilecenoğlu et al. 2002 Bilecenoğlu M., Taskavak E., Mater S., Kaya M. 2002. Checklist of the marine fishes of Turkey. Zootaxa 113: 1-194. https://doi.org/10.11646/zootaxa.113.1.1 : 149 (Turkey). Cabral et al. 2002 Cabral H.N., Lopes M., Loeper R. 2002. Trophic niche overlap between flatfishes in a nursery area on the Portuguese coast. Sci. Mar. 66: 293-300. https://doi.org/10.3989/scimar.2002.66n3293 : 97 (Portugal; trophic niche overlap). Fricke et al. 2007 Fricke R., Bilecenoğlu M., Sari H.M. 2007. Annotated checklist of fish and lamprey species (Gnathostomata and Petromyzontomorphi) of Turkey, including a Red List of threatened and declining species. Stuttg. Beitr. Naturk. Ser. A (Biol.) 706: 1-169.: 114 (Turkey). Henriques et al. 2007 Henriques M., Gonçalves E.J., Almada V.C. 2007. Rapid shifts in a marine fish assemblage follow fluctuations in winter sea conditions. Mar. Ecol. Progr. Ser. 340: 259-270. https://doi.org/10.3354/meps340259 : 270 (Portugal). Pakhorukov 2008 Pakhorukov N.P. 2008. Visual observations of fish from seamounts of the southern Azores region (the Atlantic Ocean). Vopr. Ikhtiol. 48 (1): 120-139. [In Russian. English translation appeared in J. Ichth. 48: 114-123.] https://doi.org/10.1134/S0032945208010104 : 137 [121] (Irving, Meteor, Hyéres, Josephine and Ampere seamounts, southern Azores region). Wirtz et al. 2008 Wirtz P., Fricke R., Biscoito M.J. 2008. The coastal fishes of Madeira Island - new records and an annotated check-list. Zootaxa 1715: 1-26. https://doi.org/10.11646/zootaxa.1715.1.1 : 19 (Madeira). Abecasis et al. 2009 Abecasis D., Cardigos F., Almada F., Gonçalves J.M.S. 2009. New records on the ichthyofauna of the Gorringe Seamount (Northeastern Atlantic). Mar. Bio. Res., online-first: 1-7.: 4 (Gorringe Seamount). Lipej and Dulčić 2010 Lipej L., Dulčić J. 2010. Checklist of the Adriatic Sea fishes. Zootaxa 2589: 1-92. https://doi.org/10.11646/zootaxa.2589.1.1 : 72 (Croatia, Adriatic Sea). Carneiro et al. 2014 Carneiro M., Martins R., Landi M., Costa F.O. 2014. Updated checklist of marine fishes (Chordata: Craniata) from Portugal and the proposed extension of the Portuguese continental shelf. Europ. J. Taxon. 73: 1-73. https://doi.org/10.5852/ejt.2014.73 : 61 (Portugal). Jaramillo et al. 2014 Jaramillo A.M., Tomberi A.D., Dura V.B., Rodrigo M.E. 2014. Otolith eco-morphological patterns of benthic fishes from the coast of Valencia (Spain). Thalassas 30: 57-66.: 64 (Valencia/Spain). Martins and Carneiro 2018 Martins R., Carneiro M. 2018. Manual de identificação de peixes ósseos da costa continental portuguesa. Principais características diagnosticantes. IPMA, Instituto Português do Mar e da Atmosfera, Lisboa: 1-204.: 78 (Portugal; Galicia/Spain). Artüz and Fricke 2019 Artüz M.L., Fricke R. 2019. The marine teleost fishes of the Sea of Marmara; an updated and annotated checklist. Zootaxa 4565: 545-565. https://doi.org/10.11646/zootaxa.4565.4.9 : 560 (Sea of Marmara/Turkey). Almeida and Biscoito 2019 Almeida A.J., Biscoito M. 2019. Results of the research expedition Biaçores 1971. Fishes and list of stations. Cybium 43: 153-161.: 153 (Azores). Carneiro et al. 2019 Carneiro M., Martins R., Reiner F., Batista I. 2019. Ichthyofauna of Portugal: taxonomic diversity, common and scientific names of marine fishes. Volume 1. Instituto Português do Mar e da Atmosfera, Lisboa: 1-376.: 189 (Portugal; Azores; Madeira). Elbaraasi et al. 2019 Elbaraasi H., Elabar B., Elaabidi S., et al. 2019. Updated checklist of bony fishes along the Libyan coast (southern Mediterranean Sea). Medit. Mar. Sci. 20: 90-105. https://doi.org/10.12681/mms.15570 : 101 (Libya). Parenti 2019 Parenti P. 2019. The status of the fishes described from Sicily by Rafinesque. FishTaxa 4: 99-124.: 101. Amaoka et al. 2020 Amaoka K., Matsuura K., Carpenter K.E., Munroe TA 2020. Arnoglossus imperialis. IUCN Red List Threatened Spec. 2020, e.T154687A15522283: 1-10.: 4 (part: northeastern Atlantic and Mediterranean). Kovačić et al. 2020 Kovačić M., Lipej L., Dulčić J. 2020. Evidence approach to checklists: critical revision of the checklist of the Adriatic Sea fishes. Zootaxa 4767: 1-55. https://doi.org/10.11646/zootaxa.5144.1.1 : 27 (Adriatic Sea). Bañón and Maño 2021 Bañón R., Maño T. 2021. Revisión taxonómica de la ictiología marina de Galicia: Clase Actinopteri (Orden Trachiniformes al Orden Tetraodontiformes). Nov. Acta Cient. Compostelana (Biol.) 28: 77-104. https://doi.org/10.15304/nacc.id7286 : 96 (Galicia/Spain). Kovačić et al. 2021 Kovačić M., Lipej L., Dulčić J., et al. 2021. Evidence-based checklist of the Mediterranean Sea fishes. Zootaxa 4998: 1-115. https://doi.org/10.11646/zootaxa.5144.1.1 : 44 (Mediterranean Sea).
Neotype of Bothus imperialis Rafinesque 1810, Bothus punctatus Rafinesque 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 and Charybdia rhomdoidichthys Facciolà 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.] (designated herein) : SMNS 27387, male, 118.7 mm SL, Balearic Islands, northeast of Ibiza, 39°09’40.8’’N 1°39’10.8’’E, 108 m depth, Francesc Ordines, R/V Miguel Oliver, Cruise MEDITS_PITIUSES_2021, St. 11, 20 Aug. 2021.
Neotype of Rhombus cristatus Lowe 1839 Lowe R.T. 1839. A supplement to a synopsis of the fishes of Madeira. Proceedings of the Zoological Society of London 1839: 76-92. https://doi.org/10.1111/j.1096-3642.1839.tb01431.x (designated herein): BMNH 1895.7.16.7, 1 male, 110.8 mm SL, Madeira, J. Y. Johnson, 1895.
Other material: HUJ 20600 (3), Balearic Islands, northwest of Menorca, 63-64 m depth; HUJ 20638 (1), Balearic Islands, northeast of Mallorca, 144-139 m depth; CFP_IEOMA 7769 (5), Balearic Islands, southeast of Menorca, 133 m depth; CFP_IEOMA 7770 (2), Balearic Islands, northeast of Ibiza, 108 m depth; CFP_IEOMA 7771 (2), eastern Atlantic, Spain, Cádiz Province, 110 m depth; CFP_IEOMA 7772 (1), Balearic Islands, northwest of Ibiza, 130 m depth; CFP_IEOMA 7773 (4), Balearic Islands, northwest of Ibiza, 125 m depth; SMNS 27384 (2), Balearic Islands, northeast of Ibiza, 108 m depth; SMNS 27385 (2), Balearic Islands, southeast of Menorca, 133 m depth; SMNS 27386 (4), eastern Atlantic, Spain, Cádiz Province, 110 m depth; SMNS 27390 (1), Balearic Islands, north of Cabrera, 49-61 m depth; SMNS 27393 (1), Balearic Islands, northwest of Menorca, 148-152 m depth; SMNS 27396 (1), Balearic Islands, southeast of Menorca, 130-134 m depth.
| Neotype of Bothus imperialis Rafinesque, 1810, Bothus punctatus Rafinesque, 1810 and Charybdia rhomdoidichthys Facciolà, 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.]: SMNS 27387 (Baleares Islands, northeast of Ibiza) | Neotype of Rhombus cristatus Lowe, 1839 Lowe R.T. 1839. A supplement to a synopsis of the fishes of Madeira. Proceedings of the Zoological Society of London 1839: 76-92. https://doi.org/10.1111/j.1096-3642.1839.tb01431.x , BMNH 1895.7.16.7 (Madeira) | Other material: SMNS 27384 (2), 27385 (2), 27386 (4), 27390 (1), 27393 (1), 27396 (1) | ||
|---|---|---|---|---|
| Sex | Male | Male | Males (n = 9) | Females (n = 2) |
| Dorsal-fin rays | 101 | 96 | 98-101 | 97-98 |
| Anal-fin rays | 75 | 74 | 74-79 | 76-77 |
| Pectoral-fin rays (ocular side) | 10 | 10 | 11 | 10-11 |
| Pectoral-fin rays (blind side) | 10 | 7 | 9-10 | 9-10 |
| Caudal-fin rays | ii,13,ii | ii,13,ii | ii-iii,11-13,ii-iii | iii,11,iii |
| Lateral-line scales | 58 | 63 | 58-62 | 61 |
| Gill rakers on first arch, lower branch (ocular side) | 8 | 8 | 7-9 | 8-9 |
| Vertebrae | 10 + 31 | 10 + 32 | 10 + 31-32 | 10 + 33 |
| Measurement: | ||||
| SL | 118.7 | 110.8 | 92.0-146.9 | 92.0-104.0 |
| Proportions (% of SL): | ||||
| Head length (ocular side) | 24.8 | 25.4 | 24.7-25.7 | 24.8-26.3 |
| Body depth | 38.7 | 40.8 | 36.1-43.9 | 36.6-39.0 |
| Upper orbit diameter | 7.6 | 8.4 | 6.7- 8.4 | 7.1- 7.7 |
| Lower orbit diameter | 7.5 | 8.2 | 6.7- 8.4 | 7.1- 7.6 |
| Interorbital width | 0.7 | 1.0 | 0.4- 0.8 | 0.4 |
| Upper jaw length ocular side) | 8.1 | 8.5 | 7.9- 8.7 | 8.5- 8.8 |
| Lower jaw length (ocular side) | 5.7 | 7.4 | 5.7- 6.9 | 6.8- 7.0 |
| Lower jaw length (blind side) | 5.5 | 6.3 | 5.5- 6.6 | 6.5- 7.1 |
| Caudal peduncle depth | 9.3 | 8.7 | 8.5-10.2 | 8.8- 9.0 |
| Length of longest dorsal-fin ray | 17.9 | 15.5 | 16.4-23.1 | 7.3- 7.9 |
| Length of longest anal-fin ray | 11.5 | 9.5 | 11.0-11.5 | 9.1-12.9 |
| Pectoral-fin length (ocular side) | 17.3 | 15.2 | 16.6-19.1 | 17.0-17.9 |
| Pectoral-fin length (blind side) | 7.7 | 10.1 | 7.8-11.8 | 8.2 |
| Pelvic-fin length (ocular side) | 19.1 | 15.3 | 13.6-19.1 | 15.2 |
| Pelvic-fin length (blind side) | 11.9 | 12.4 | 10.2-11.9 | 10.1-11.0 |
| Length of pelvic-fin base (ocular side) | 9.3 | 8.6 | 6.6- 9.9 | 8.0-8.8 |
| Length of pelvic-fin base (blind side) | 4.4 | 7.4 | 3.4- 5.0 | 4.0- 5.0 |
| Length of longest caudal-fin ray | 19.0 | 20.1 | 17.8-20.4 | 18.5-20.5 |
Diagnosis. A species of Arnoglossus with the second to fifth, sixth or seventh (male), second to third (female) dorsal-fin rays elongate and filamentous, dorsal-fin rays 96-101, anal-fin rays 74-82, pectoral-fin rays on ocular side 10-11, on blind side 9-10, caudal-fin rays ii-iii,11-13,ii-iii , lateral-line scales 58-63, gill rakers 0 + 8-9, not serrated, interorbital a narrow bony ridge without scales in the middle, interorbital width 4%-11% of upper orbit diameter, no enlarged teeth anteriorly in upper jaw, and prevomer small, not enlarged, weakly projecting into mouth cavity; ocular side yellowish, blind side whitish, fins translucent, spotted with brown; male dorsal-fin filaments white (maybe basally greyish).
Description. Counts and measurements of the neotype of Bothus imperialis Rafinesque 1810, the neotype of Rhombus cristatus Lowe 1839 Lowe R.T. 1839. A supplement to a synopsis of the fishes of Madeira. Proceedings of the Zoological Society of London 1839: 76-92. https://doi.org/10.1111/j.1096-3642.1839.tb01431.x , and other material listed in Table 4 are part of this description.
Body oval, laterally strongly compressed, eyes on the left side of body (“ocular side”), right side of body without eyes (“blind side”). Body depth 2.6 (2.4) [2.3-2.8] in SL, 38.7 (40.8) [36.1-43.9]% of SL. Head length 4.0 (3.9) [3.8-4.2] in SL, 24.8 (25.4) [24.0-26.3]% of SL Snout slightly pointed, not completely scaled, tip naked. Anterior teeth in upper jaw not enlarged, prevomer not enlarged, weakly projecting into mouth cavity. Anterior nostril situated anterior to the eyes, posterior nostril on level of anterior margin of eyes. Upper orbit diameter 3.5 (3.2) [3.2-4.0] in head length, 7.6 (8.4) [6.7-8.4]% of SL; lower orbit diameter 3.6 (3.3) [3.2-4.0] in head length, 7.5 (8.2) [6.7-8.4]% of SL. Interorbital a narrow, low bony ridge, in the middle without scales, interorbital distance 0.7 (1.0) [0.4-0.8]% of SL. Scales on orbital and blind sides cycloid. Lateral line barely arched over pectoral fin (arch formed by anterior 17-18 scales); lateral-line scales 58 (63) [58-62]. Caudal peduncle depth 10.8 (11.5) [9.8-11.8] in SL, 9.35 (8.7) [8.5-10.2]% of SL. Precaudal vertebrae 10 (10) [10], caudal vertebrae 31 (32) [31-33].
Dorsal fin with 101 (96) [97-101] soft rays, the second to fifth to seventh rays (male), second to third (female) elongate and filamentous. Anal fin with 75 (74) [74-79] soft rays. Caudal fin distally rounded, caudal fin rays ii,13,ii (ii,13,ii) [ii-iii,11-13,ii-iii]. Length of longest caudal-fin ray 5.3 (5.0) [4.9-5.6] in SL, 19.0 (20.1) [17.8-20.5]% of SL. Pectoral fin with 10 (10) [10-11] soft rays on ocular side, with 10 (7) [9-10] rays on blind side. Pectoral-fin length 5.8 (6.6) [5.2-7.3] in SL, 17.3 (15.2) [16.6-19.1]% of SL on ocular side, 13.0 (9.9) [8.4-12.9] in SL, 7.7 (10.1) [7.7-11.8]% of SL on blind side. Pelvic-fin length 5.2 (6.5) [5.1-7.4] in SL, 19.1 (15.3) [13.6-19.2]% of SL] on ocular side, 8.4 (8.0) [8.4-9.9] in SL, 11.9 (12.4) [10.1-11.9]% of SL on blind side.
Colour of fresh specimens ( Figs 10 , 11 ). Head and body with ocular side yellowish in both sexes, margins of scales brown, head brown, opercle grey; blind side pale in both sexes, head pale, belly white (liver can be seen through it as a circular black blotch); peritoneum black on eyed side, silvery white on blind side. Dorsal-fin filaments of males plain white, may be basally greyish; dorsal, anal and caudal fins pale, with irregular brown spots; pelvic fins dark grey. Pectoral fins on both sides translucent, on ocular side with brown spots.
Colour in preservative ( Fig. 6-9Figs. 6, 7, 8, 9 ). Similar to live colouration, but fading to pale yellowish.
Distribution. Northeastern Atlantic Ocean (UK, Ireland, France, Portugal, Spain, Madeira, Azores, seamounts in the Azores region), Mediterranean Sea (Spain, France, Italy, Croatia, Libya, Turkey), Sea of Marmara (Turkey) ( Fig. 5 ). This species has been collected on sand bottoms at 15-350 m depth.
Genetics. A total of 376 (32 variable sites, 31 informative sites) and 523 (135 variable sites and 132 informative sites) base pairs (bp) for 12s rRNA and COI mitochondrial fragments were sequenced, respectively. The average interspecific divergence for the 12s rRNA fragments between any two species of Arnoglossus was 3.9% and 14.8 bp differences. Arnoglossus blachei showed the closest genetic distance to A. rueppelii (2.82% and 10.5 bp differences, Table 5 ). This genetic distance was larger than the interspecific distance observed in other species of Arnoglossus such as A. imperialis vs. A. thori (0.81% and 3 pb differences) and A. capensis vs. A. thori (0.99% and 3.7.5 pb differences). Based on the COI fragments, the average interspecific distance between the species of Arnoglossus was 12.98% and 67.9 pb differences. The closest genetic distance of A. blachei was observed with A. rueppelii (10.07% and 52.7 bp differences, Table 5 ). This genetic distance was greater than the interspecific distance observed in other species of Arnoglossus such as A. capensis vs. A. imperialis (4.69% and 24.5 pb differences) and A. imperialis vs. A. thori (8.34% and 43.6 pb differences).
| A. blachei | A. capensis | A. imperialis | A. laterna | A. rueppellii | A. thori | |
|---|---|---|---|---|---|---|
| A. blachei | -- | 81.7 | 82.5 | 74.3 | 52.7 | 78.7 |
| A. capensis | 15.62 | -- | 24.5 | 80.7 | 75.7 | 45.7 |
| A. imperialis | 15.78 | 4.69 | -- | 81.4 | 75.4 | 43.6 |
| A. laterna | 14.21 | 15.42 | 15.56 | -- | 75.3 | 72.7 |
| A. rueppellii | 10.07 | 14.47 | 14.42 | 14.40 | -- | 73.5 |
| A. thori | 15.04 | 8.73 | 8.34 | 13.89 | 14.05 | -- |
The phylogenetic reconstruction for concatenated fragments clearly separates A. blachei from other species of Arnoglossus species included in the present study, with the phylogenetically closest species being A. rueppelii ( Fig. 12 ). These two species are placed within a major clade that includes A. laterna. In addition, a second major clade is observed, including A. imperialis, A. capensis and A. thori ( Fig. 12 ).
Remarks. Some of the previously recognized synonyms of A. imperialis are here confirmed, including Bothus punctatus Rafinesque, 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 , Arnoglossus lophotes Günther 1862 Günther A.C.L.G. 1862. Catalogue of the fishes in the British Museum. Catalogue of the Acanthopterygii, Pharyngognathi and Anacanthini in the collection of the British Museum. Volume 4. British Museum, London: i-xxi + 1-534. and Charybdia rhomdoidichthys Facciolà, 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.]. However, the original description of Bothus imperialis Rafinesque, 1810 from northern Sicily (Italy) is very brief and does not allow a clear identification as the Arnoglossus imperialis of current usage. No type material of this taxon is extant, nor is any available for Bothus punctatus Rafinesque 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 or Charybdia rhomdoidichthys Facciolà, 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.] (see Fricke et al. 2022b Fricke R., Eschmeyer W. N., Laan R. van der (eds) 2022b. Eschmeyer’s catalog of fishes, electronic version (6 June 2022). Internet publication, San Francisco (California Academy of Sciences). http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp ). In order to stabilize the current usage of these names, a neotype is hereby selected for Bothus imperialis Rafinesque, 1810 Rafinesque C.S. 1810b. Indice d’ittiologia siciliana; ossia, catalogo metodico dei nomi latini, italiani, e siciliani dei pesci, che si rinvengono in Sicilia disposti secondo un metodo naturale e seguito da un appendice che contiene la descrizione de alcuni nuovi pesci siciliani. G. del Nobolo, Messina: 1-70, pls. 1-2. https://doi.org/10.5962/bhl.title.58965 , Bothus punctatus Rafinesque, 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 and Charybdia rhomdoidichthys Facciolà, 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.]: SMNS 27387 (male, 118.7 mm SL, Balearic Islands, northeast of Ibiza) ( Figs 6 , 7 ). This specimen originates as close as practical to the original localities (northern Sicily, Italy); we preferred to select a fresh specimen of which we had seen the live colouration after it had been collected. The neotype of Rhombus cristatus agrees well with the characters of the Arnoglossus imperialis of current usage, including a high number of lateral-line scales and plain white dorsal-fin filaments. This neotype designation links the three names involved, and fixes Bothus punctatus Rafinesque, 1814 Rafinesque C.S. 1814. Précis des découvertes et travaux somiologiques de Mr. C. S. Rafinesque-Schmaltz entre 1800 et 1814; ou choix raisonné de ses principales découvertes en zoologie et en botanique, pour servir d’introduction à ses ouvrages futurs. Palermo: 1-55. https://doi.org/10.5962/bhl.title.6135 and Charybdia rhomdoidichthys Facciolà, 1885 Facciolà L. 1885. Su di alcuni rari Pleuronettidi del Mar di Messina. Nota preliminare. Natur. Sicili. 4: 261-266. [Also appeared as a separate, pp. 1-6.] as permanent synonyms of Arnoglossus imperialis (Rafinesque, 1810).
During our studies on the synonymy of A. imperialis, another, unused synonym of A. imperialis was detected, i.e. Rhombus cristatus Lowe 1839 from Madeira. No type material of this taxon is extant ( Fricke et al. 2022b Fricke R., Eschmeyer W. N., Laan R. van der (eds) 2022b. Eschmeyer’s catalog of fishes, electronic version (6 June 2022). Internet publication, San Francisco (California Academy of Sciences). http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp ). In order to establish the identity of this name, a neotype is hereby selected to stabilize its usage: BMNH 1895.7.16.7 (male, 110.8 mm SL, Madeira, J. Y. Johnson, 1895) ( Figs 8 , 9 ). The neotype is needed owing to a possible confusion of Madeira populations with A. blachei; the neotype originates as close as practical to the original locality (Madeira). The neotype of Rhombus cristatus agrees well with the characters of Arnoglossus imperialis, including a high number of lateral-line scales, caudal-fin rays ii,13,ii, and plain white dorsal-fin filaments.
This species apparently prefers cooler water; in the western Mediterranean, it is mainly found in regions with cool upwelling water, e.g. in southern France and Liguria, and off the northern coasts of Menorca or Sicily islands. In recent years, it has become rare in some of these habitats, so it may now be considered Near Threatened in the Mediterranean. Amaoka et al. (2020) Amaoka K., Matsuura K., Carpenter K.E., Munroe TA 2020. Arnoglossus imperialis. IUCN Red List Threatened Spec. 2020, e.T154687A15522283: 1-10. treated this species as of Least Concern, with population trends unknown, but they did not distinguish between populations of A. imperialis and A. blachei in their assessment.
DISCUSSION
⌅The specimens of Arnoglossus blachei described herein agree well with the generic characters of the genus Arnoglossus as defined by Norman (1934) Norman J.R. 1934. A systematic monograph of the flatfishes (Heterosomata). Volume 1. Psettodidae, Bothidae, Pleuronectidae. British Museum (Natural History): viii + 459 pp. https://doi.org/10.5962/bhl.title.8585 and Amaoka (1969) Amaoka K. 1969. Studies on the sinistral flounders found in the waters around Japan: taxonomy, anatomy and phylogeny. J. Shimonoseki Univ. Fish. 18: 65-340., including the pelvic fin on the ocular side beginning at the tip of the isthmus, the eyes separated by a bony ridge, the head large, more than 22% of SL (i.e. 23.2%-24.7%), the scales on the ocular side cycloid, and the mouth large, maxillary longer than eye diameter. However, they are clearly distinct from other species of Arnoglossus bearing filaments on the first dorsal fin; these species are compared in Table 6 . Arnoglossus blachei is distinguished from A. imperialis by the live colouration of the lower side of the males which is bright red (whitish in A. imperialis) ( Figs 4 , 11 ), lateral-line scales 49-58 (vs. 58-66), and the dorsal-fin filaments in the male light grey, with black margins, distally yellowish (vs. plain white), the length of the second and third dorsal rays in males (including filaments) 23.9%-34.7% and 23.6%-37.1% of SL, respectively (vs. 13.4%-19.1% and 16.4-23.1% of SL, respectively), and gill rakers usually 5-8 (usually 6-7) [vs. 7-9 (usually 8-9)]. Unexpectedly, for both fragments studied here, Arnoglossus blachei was genetically more similar to A. rueppelii than to any other of the species compared. However, the interspecific divergences between A. blachei and A. rueppelii were high (2.82% and 10.07% for 12s rRNA and COI, respectively). The divergence value for this last fragment significantly exceeds the standard threshold for marine fish species delimitation which is 2% for this fragment ( Hubert et al. 2008 Hubert N., Hanner R., Holm E., et al. 2008. Identifying Canadian freshwater fishes through DNA barcodes. PLoS ONE 3 (e2490): 1-8. https://doi.org/10.1371/journal.pone.0002490 , Ward et al. 2009 Ward R.D., Hanner R., Hebert P.D.N. 2009. The campaign to DNA barcode all fishes, FISH-BOL. J. Fish Biol. 74: 329-356. https://doi.org/10.1111/j.1095-8649.2008.02080.x , April et al. 2012 April J., Hanner R.H., Dion-Cote A.M., Bernatchez L. 2012. Glacial cycles as an allopatric speciation pump in north-eastern American freshwater fishes. Molec. Ecol. 22: 409-422. https://doi.org/10.1111/mec.12116 ). On the other hand, although for 12s RNA there is no standard species delimitation value, Cawthorn et al. (2012) Cawthorn D.M., Steinman H.A., Witthuhn R.C. 2012. Evaluation of the 16S and 12S RNA genes as universal markers for the identification of commercial fish species in South Africa. Gene 491: 40-48. https://doi.org/10.1016/j.gene.2011.09.009 proposed 0.5% as a threshold, a lower percentage than for COI, which may be related to its lower mutation rate ( Palumbi 1996 Palumbi S.R. 1996. Nucleic acids II: the polymerase chain reaction. pp. 205-248. In: Hillis DM, Moritz C, Mable BK, (eds) Molecular Systematics. Sunderland, Massachusetts (Sinauer Associates Inc.).). Thus, the divergence detected for this fragment also confirms A. blachei as a valid species. This is also clear from the phylogenetic analyses of the concatenated fragments, which showed different lineages between A. blachei and A. rueppelii.
| A. blachei | A. nigrofilamentosus | A. tapeinosoma | A. macrolophus | A. elongatus | A. capensis | A. imperialis | A. thori | |
|---|---|---|---|---|---|---|---|---|
| Dorsal-fin rays | 89-99 | 78-84 | 91 | 91-98 | 100-108 | 96-105 | 96-106 | 81-91 |
| Elongate dorsal fin rays | rays 2 to 5 | rays 2 to 6 | none | rays 1 to 8 (male), rays 1 to 2 (female) | rays 2 to 4 (male), none (female) | rays 1 to 4 | rays 2 to 5-7 (male), rays 2 to 3 (female) | ray 1 in males |
| Colour of filaments | light grey, rays with black margins, basally yellowish | black | not applicable (anterior dorsal fin light brown) | brown | light brown | light brown | white | black |
| Anal-fin rays | 64-77 | 61-66 | 69 | 70-76 | 78-83 | 74-81 | 74-82 | 61-69 |
| Pectoral-fin rays (ocular side) | 10-12 | 12-13 | 11 | 12-14 | 12 | 10-13 | 10-12 | 10-12 |
| Pectoral-fin rays (blind side) | 7-10 | 7-9 | 9 | 8-11 | 10 | 9-12 | 7-10 | 8-9 |
| Caudal-fin rays | iii,11,iii | iii,11,iii | iii,11,iii | ii,13,ii | ii,14,ii | iii,14,iii | ii-iii,11-14,ii-iii | ii-iii,13,ii-iii |
| Lateral-line scales | 45-57 | 52-54 | 53 | 55-62 | 63-70 | 56-67 | 58-66 | 49-56 |
| Gill rakers | 0 + 5-8 (usually 0 + 6-7) | 0 + 4-5 | 0 + 8 | 0 + 10-13 | 0 + 6-7 | 0 + 10-13 | 0 +7-10 | 0 + 7-9 |
| Condition of gill rakers | not serrated | not serrated | not serrated | not serrated | not serrated | not serrated | not serrated | not serrated |
| Vertebrae | 10 + 30-33 | 10 + 30 | 10 + 30 | 10 + 31-32 | ? | 10 + 33 | 10 + 32-35 | 10 + 27-30 |
| Head length (% of SL) | 23-28 | 23-25 | 23 | 23-28 | 27-28 | 22-28 | 22-28 | 26-31 |
| Body depth (% of SL) | 40-46 | 40-44 | 39 | 36-43 | 35-36 | 40-45 | 36-45 | 45-62 |
| Length of 2nd dorsal-fin ray in male (% of SL) (if filamentous) | 24-35 | 10-13 | -- | 27-50 | 17-26 | 12-16 | 13-19 | 17-21 |
| Length of 3rd dorsal-fin ray in male (% of SL) (if filamentous) | 24-37 | 10-13 | -- | 28-54 | 18-28 | 12-17 | 16-23 | -- |
| Interorbital | bony ridge, no scales | bony ridge, no scales | bony ridge, no scales | bony ridge, no scales | bony ridge, no scales | broad, scaly, concave | bony ridge, no scales | bony ridge, no scales in juveniles; narrow concave, scaled space in adults |
| Interorbital (% of upper orbit diameter) | 4-17 | 11-16 | 11 | 10-14 | 10-14 | 30-40 | 4-11 | 13-25 |
| Prevomer | small, weakly projecting into mouth cavity | small, weakly projecting into mouth cavity | small, weakly projecting into mouth cavity | large, strongly projecting into mouth cavity | small, weakly projecting into mouth cavity | small, weakly projecting into mouth cavity | small, weakly projecting into mouth cavity | small, weakly projecting into mouth cavity |
| Distribution | eastern Atlantic from Morocco south to Namibia; Canary Islands | [Gulf of Suez?] eastern Mediterranean | Sumatra (Indonesia), China | central Red Sea and Persian Gulf east to Indonesia | Taiwan to Indonesia and northwestern Australia | Morocco to South Africa | Mediterranean and eastern Atlantic from Scotland to Strait of Gibraltar; Azores and Madeira | Mediterranean and Black seas, and eastern Atlantic from Ireland to Sierra Leone |
| Depth | 34-175 | ca. 20-30 | ? | 18-141 | 100-224 | 70-200 | 15-350 | 5-300 |
Key to the species of Arnoglossus of the Mediterranean Sea and the eastern Atlantic
Remark: This key has been updated on the basis of Munroe (2016) Munroe T.A. 2016. Bothidae. pp. 2973-2993. In: Carpenter, K.E., De Angelis N. (eds). 2016. The living marine resources of the Eastern Central Atlantic. Volume 4. Bony fishes part 2 (Perciformes to Tetradontiformes) and Sea turtles. FAO Species Identification Guide for Fishery Purposes, Rome, FAO: i-xiii + 2343-3124., Nielsen in Whitehead et al. (1986) Whitehead P.J.P., Bauchot M.-L., Hureau J.-C., et al. 1986. Fishes of the North-eastern Atlantic and the Mediterranean. Volume 3. UNESCO, Paris: 1015-1473. https://doi.org/10.2307/1444931 , and Fricke et al. (2017) Fricke R., Golani D., Appelbaum-Golani B. 2017. Arnoglossus nigrofilamentosus n. sp., a new species of flounder (Teleostei: Bothidae) from off the Mediterranean coast of Israel, probably a new case of Lessepsian migration. Sci. Mar. 81: 257-265. https://doi.org/10.3989/scimar.04684.07A .
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1a. Dorsal-fin rays 110-118; anal-fin rays 86-94 ... A. rueppellii
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1b. Dorsal-fin rays less than 110; anal-fin rays less than 85 ... 2
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2a. Gill rakers 0 + 4-5; dorsal and anal fins plain black ... A. nigrofilamentosus
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2b. Gill rakers 0 + 7-13; dorsal and anal fins pale, sometimes with dark spots or only anterior rays black ... 3
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3a. Dorsal-fin rays 74-80; anal-fin rays 51-57 ... A. grohmanni
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3b. Dorsal-fin rays 81 or more; anal-fin rays 61 or more ... 4
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4a. Dorsal-fin rays 81 to 93; anal-fin rays 61 to 74; at most one elongate dorsal-fin ray ... 5
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4b. Dorsal-fin rays 95 to 106; anal-fin rays 74 to 82; two or more elongate dorsal-fin rays ... 6
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5a. No elongate dorsal-fin rays; no dark markings on ocular-side pectoral fin; no series of dark spots present along base of caudal fin ... A. laterna
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5b. Second dorsal-fin ray of males elongate (more than 60% of head length) with dark-fringed, broad membrane (1st, 3rd and 4th dorsal-fin rays may also be elongate, but these are only about one-third as long as second ray); ocular-side pelvic fin often with dark spot or blotch on posterior rays; a series of dark spots often present along base of caudal fin ... A. thori
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6a. Dorsal-fin rays 2 to 5 (-7) elongate (elongate rays nearly equal to head length in males); eyes separated by a bony ridge; lateral-line scales 52 to 66; 5 to 10 gill rakers on lower limb of first gill arch ... 7
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6b. Anterior 3 or 4 dorsal-fin rays of males noticeably prolonged and of nearly equal length; eyes separated by a concave scaly space; lateral-line scales 56 to 67; 10 to 13 gill rakers on lower limb of first gill arch ... A. capensis
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7a. Lateral-line scales 58-66; dorsal-fin rays 96-106; anal-fin rays 74-82; gill rakers 0 + 8-10; ventral side of males pale in life; dorsal-fin filaments in male plain whitish ... A. imperialis
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7b. Lateral-line scales 52-57; dorsal-fin rays 89-99; anal-fin rays 64-78; gill rakers 0 + 5-8 (usually 0 + 6-7); ventral side of males bright red in life; dorsal-fin filaments in male light grey, with black margins, distally yellowish ... A. blachei