Species of Galacantha and Munidopsis (Crustacea: Decapoda: Anomura: Galatheidae) from the deep-waters off Taiwan, with the description of two new species

One species of the genus Galacantha A. Milne-Edwards, 1880, and 20 species of Munidopsis Whiteaves, 1874, including two new species, are reported from the deep-waters off Taiwan. Munidopsis echinata n. sp. closely resembles M. colombiana Pequegnat and Pequegnat, 1971 from the Caribbean Sea, but differs in lacking an antennal spine on the carapace and having a much longer antennal peduncle. Munidopsis tuberosa n. sp. appears close to M. granosicorium Williams and Baba, 1990 from the northeast Pacific, but the configuration of the carapace and rostrum separates these two species. Altogether 31 species of Munidopsis are now recorded from Taiwan, indicating a particularly rich deep-sea fauna of the island.

Coloration (Fig. 1B): Carapace generally reddish orange, anterior part of rostrum and cervical grooves whitish. Abdomen reddish orange on second and third segments but whitish on fourth to sixth segments, telson, and uropods. Corneas orange pink. Pereopods white to pale orange.
Remarks: The specimen examined agrees well with the description of Macpherson (2007).
Munidopsis analoga closely resembles M. cylindropthalma, which also occurs in Taiwan. In addition to the difference in the length of P1 discussed by Macpherson (2007), the two species are distinguished by the armature on the merus of Pl. This segment has three distal spines (lateral, mesial, and dorsal) in M. analoga, but it possesses only one distolateral spine in M. cylindrophthalma.

Munidopsis arietina
Remarks: In the specimens examined, there are two spines on the anterior branchial margin of the carapace, and the posterior spine is much smaller than the anterior (no posterior spine for M. arietina as described in Alcock andAnderson,1894 andBaba, 2005). This armature agrees fairly well with that of a close relative, M. bairdii (Smith, 1884). However, M. arietina can be distinguished from M. bairdii by the eye-spine being directed anterolaterad (Baba, 2005).
The two specimens examined are different in the arrangement of spines on the carapace and rostrum.
The anterior carapace has two mesogastric spines in both specimens, but the protogastric spine is present only in the male. The median end of the cervical grooves also possesses a pair of small spines only in the male. The cardiac region is armed with two pairs of spines. The posterior pair is much smaller than the anterior pair in the male, and it is reduced to a minute tubercle or a short ridge in the female. The posterior elevated ridge bears seven spines in the male, but two median spines in the female. The lateral margin of the rostrum is armed with six left and five right spines in the male, and three left and two right spines in the female. Moreover, the male specimen has a small antennal spine on the right frontal margin of the carapace.

Munidopsis cidaris
Remarks: Although the only specimen collected lacks both P1, it generally agrees with the original description of M. cidaris. The squamiform ridges on the gastric region of the carapace are larger in the present specimen than the holotype. The corneas are subtriangular in the Taiwanese specimen instead of rounded as they are in the holotype.
Distribution: Off central Queensland, Australia, the Philippines and Solomon Islands, at depths of 975-1200 m. The Taiwan specimen was obtained from depths of 736-1040 m. Alcock, 1894 ( Fig. 2A the carapace ( Fig. 2A), but the spine is absent in the Taiwanese material of its close relative M. kensleyi Ahyong and Poore, 2004. Although Ahyong and Poore (2004) mentioned that M. dasypus differs from M. kensleyi in having longer and more upright spines on the P1-4, our material of these two species shows no clear differences in the spines. The deep excavation on the anterior median part of the thoracic sternite 4 illustrated in Baba (1988: Fig. 60b) is not clearly seen in the present specimen, which is similar to the "Galathea" material identified as M. dasypus by Baba (2005). The Taiwanese specimens of M. kensleyi also have the excavation weakly marked or indistinct. Etymology: The specific name is derived from the Latin, echinatus, prickly, in reference to the armature on the carapace and abdomen.

Munidopsis dasypus
Description: Carapace (Fig. 3A, B), exclusive of rostrum (postorbital carapace), approximately 1.3 times longer than broad; dorsal surface moderately convex from side to side; anterior and posterior cervical groove distinct but not deep; spines, tubercles, and ridges with few short setae. Gastric region moderately convex, covered with small and moderate-sized spines and tubercles as figured; pair of epigastric spines well developed. Hepatic region with few minute tubercles. Anterior half of branchial and cardiac regions with small spines and tubercles. Posterior part of carapace bearing elevated, interrupted transverse ridges. Posterior cardiac region subtriangular, preceded by shallow transverse depression. Posterior margin preceded by elevated ridge with 4 median spines. Lateral margins subparallel, nearly straight on anterior half and slightly convex on posterior half, not crested; anterior half with strong spines; first spine anterolateral, smaller than second, somewhat divergent anteriorly, located distinctly mesial to level of remaining spines; second spine largest, directed slightly more laterad than preceding; remaining spines small or subequal to first (some spines in broken condition); small spine present at lateral end of posterior cervical groove. Frontal margin strongly oblique, slightly convex; antennal spine absent. Rostrum (distal part broken) (Fig. 3A, B) narrow, weakly upturned in lateral view; lateral margins with minute denticles; dorsal surface slightly convex, with rounded, median longitudinal carina; ventral surface with weak, rounded, longitudinal ridge in midline.
Pterygostomian flap (Fig. 3B) with flattened small tubercles on anterior half and elevated, interrupted oblique ridges on posterior half; anterior margin narrowly rounded, bearing spinule.
Sternal plastron as long as wide when measured along midline, maximum width at sternite 7. Sternite 3 ( Fig. 3C) approximately 3.3 times as broad as long when measured along midline; anterior margin divided into 2 round lobes by median notch, each lobe with small spine at each mesial and lateral end. Sternite 4 ( Fig. 3C) anteriorly narrowed, not contiguous with posterior margin of sternite 3; greatest width approximately 3.2 times that of sternite 3; anterior margins oblique, somewhat concave, each with row of flattened tubercles and setae; surface depressed in midline, with pair of tufts of short setae. Sternites 5-7 nearly smooth on surface, with row of setae on each anterior ridge. Abdomen (Fig. 3A, B) with short and moderately long setae on transverse ridges and pleura; segments 2-4 each with 2 moderately elevated, blunt transverse ridges separated by transverse groove, anterior ridges with 3 spines on segments 2 and 3 but 1 spine on segment 4; segment 5 without distinct transverse ridges, weakly convex on median surface; segment 6 ( Fig. 3D) flattish, with posteromedian lobe strongly produced, overreaching weakly convex posterolateral lobes. Telson (Fig. 3D) composed of 8 calcified plates.
Basal article of antennular peduncle ( Fig. 3E) with dorsolateral spine distinctly smaller than ventrolateral, smooth; ventrolateral spine also smooth, slender; lateral margin with spinules; ventral surface with transverse row of short denticulate scales and small spine; distomesial margin with row of small denticles and strong spine at mesial angle, small dorsal spine present.
(dorsomesial, dorsolateral, ventrolateral, and ventromesial), distal spine strongest among spines of same row; surfaces also with some smaller spines. Carpus 1.5 times longer than broad when measured on dorsodistal margin; dorsomesial and dorsolateral margins each with 2 distinct spines, distal spines larger; surfaces with some much smaller spines and protuberances. Palm comparatively slender, moderately inflated, 1.2 times length of carpus, 1.5 times as long as broad when measured at bases of fingers; lateral margin weakly concave at base of fixed finger, armed with irregular row of spines along each of dorsomesial and dorsolateral margins, dorsomesial row composed of 2 strong spines and dorsolateral row of 2 or 3 moderately large spines; dorsal surface also with 2 irregular rows of 2 spines and scattered short ridges, distolateral spine much larger; ventral surface with scattered short ridges. Fingers 1.2 times as long as palm; opposable margins nearly straight, not gaping, distally spooned; prehensile edges each with row of small subacute teeth, proximal teeth obsolete; distal margins each with row of small, rounded teeth; fixed finger without denticulate carina on distolateral surface. P2-4 ( Fig. 4C-G) long, slender, subcylindrical; both P2 missing dactyli and distal parts of propodi; left P3 lacking dactylus; right P3 overreaching tip of Pl by entire length of dactylus; P3 longer than P4; surfaces with sparse, short to moderately long setae, most numerous on dactyli. Ischia each with elevated ridge on dorsal surface; ventral surface also with few short, elevated ridges; ventrodistal margin with row of short spines. Meri longest on P2, decreasing in length posteriorly, elongate, subrectangular in lateral view, each with dorsal crest bearing row of strong spines continued onto corresponding crest on carpus, distal spine largest; lateral surface with some small spines, and also with elevated, short transverse ridges on P4; distolateral margin with rounded lobe; ventrolateral margin with irregular rows of spines, distal spine prominent; mesial surface flattish, smooth; dorsomesial and ventromesial margins each delimited by row of elevated, very short transverse ridges, and also with small spines on P4; ventrodistal margin with small spine, largest on P3; ventral surface with elevated, short transverse ridges and small spines. Carpi each with row of spines on dorsal crest, distal spine largest; lateral surface also with elevated crest bearing small proximal spine and few short ridges somewhat dorsally along midline, and oblique row of few short ridges ventrally, dis-tal ridge denticulate; ventral surface nearly smooth; ventrodistal margin produced, with slender spine; mesial surface with few very short ridges. Propodi, exclusive of distal rounded projection, 8.0-8.4 times as long as high when measured at base of distal projection; dorsal surface flattish, nearly smooth; dorsolateral and dorsomesial margins each delimited by row of elevated and flattened short ridges, few spines present on proximal half; lateral surface with weakly elevated short ridges in midline; ventral surface somewhat flattish, bearing short, transverse ridges; ventrodistal margin with 1 or 2 short corneous spines, lateral spine always present, mesial spine minute or absent; mesial surface with scattered small protuberances. Dactyli 0.5-0.6 length of propodi, each terminating in slender corneous claw; dorsal, lateral, and mesial surfaces nearly smooth; ventral margin gently curved, with row of 12 or 13 low, proximally diminishing processes, each process supporting slender corneous spine or bristle.

Remarks:
The new species is most closely allied to M. colombiana Pequegnat and Pequegnat, 1971 known from the Colombian Basin in the Caribbean Sea in almost all aspects except in having no antennal spine on the frontal margin of the carapace (a distinct antennal spine is present in M. colombiana), a long spine on the distomesial margin of the antennular basal article (two or three spines in M. colombiana, and these spines may bear accessory spinules), and the antennal peduncle overreaching the anterior margin of the cornea by the length of the article 4 (antennal peduncle not reaching anterior margin of cornea in M. colombiana).
Munidopsis echinata also resembles M. abyssicola Baba, 2005 known from Kermadec Deep in the southwest Pacific and the Atlantic Ocean, and M. gladiola Macpherson, 2007 from Walvis Ridge in the southeast Atlantic and southwest Indian Ocean. The common characters found in these three species include the carapace with some spines on the gastric region, the abdominal segment 6 with the posteromedian lobe well produced, the ocular peduncle bearing a distinct distomesial eye-spine, the P1 without epipod and a denticulate carina on the lateral surface of the fixed finger, and the P2-4 dactyli not cristate on the lateral and mesial surfaces. Munidopsis echi-nata and M. abyssicola also have the abdominal segment 6 with a strongly produced posteromedian lobe, a large distomesial eye-spine clearly overreaching the distal margin of the cornea, and the P2-4 propodi bearing some small spines on the dorsal crests and dactyli being moderately curved on the ventral margin. Moreover, the new species and M. gladiola both have a pair of prominent epigastric spines and the P1 palm armed with spines on the mesial margin. However, M. echinata is distinguished from these two species Remarks: P2 only extends to the base of the P1 dactylus in the specimen of stn CP284. In the other Taiwanese specimens as well as the material of Baba and Poore (2003) and Baba (2005), P2 overreaches P1.
Distribution: Bay of Bengal, southwest of Sri Lanka and New South Wales, at depths of 1379-2610 m. The Taiwan specimens were collected at depths of 2220-3065 m. Alcock, 1901 ( Remarks: The specimen examined agrees well with the recent diagnosis of M. granosa given by Baba (2005), except the abdominal segment 6 with the distolateral lobes distinctly overreaching the slightly convex posteromedian margin, the telson composed of ten calcified plates (a small plate is present between the lateromedian and distal plates; Fig. 2B), and the P1 fixed finger with a short denticulate carina on the distolateral margin (Fig. 2C).
Distribution: Mozambique Channel and Bay of Bengal at depths of 2610-3485 m, and Taiwan at depths of 3032-3065 m. The present record greatly extends its geographical distribution eastwards into the Pacific Ocean. Balss, 1913 ( Coloration (Fig. 2B): Carapace, abdomen, and pereopods entirely whitish; setae brown.

Munidopsis hirsutissima
Remarks. In the specimen examined, the P1 palm is robust, somewhat flattish, and about 1.4 times as long as the dactylus, and a small antennal spine is present on the left side but absent on the right side of the frontal margin of the carapace. Coloration (Fig. 5C): Entire body generally reddish orange; grooves on carapace, telson, and uropods paler coloured, whereas P1 deeper coloured. Corneas pink.

Remarks:
The lateral end of the anterior cervical groove is unarmed or has a small blunt projection in the specimens examined. The armature on the lateral margin of the carapace is a primary difference between M. kensleyi and M. dasypus (Baba, 2005: 148). Remarks: The present specimens differ in some characters from the recent description of M. pallida given by Baba (2005). The rostrum of the specimen from stn CP374 (Fig. 2E) is much more strongly upturned than the other specimens examined (Fig.  2D) and the specimen from the Bay of Bengal of Baba (2005). In the specimens from stn CP369 and CP374, the anteroateral spine of the carapace is directed somewhat anterolaterally (vs. directed straight forward). The dactyli of the P2-4 are considerably narrowed distally in the Taiwanese specimens (vs. relatively broad distally).
Distribution. Bay of Bengal at depths of 2610-3299 m, and Taiwan at depths of 2233-3070 m. The present record greatly extends its geographical distribution eastwards into the Pacific Ocean. Henderson, 1885 ( Fig. 6A Coloration (Fig. 6A): Entire body and pereopods whitish; setae pale brown. Corneas orange pink.

Remarks:
The specimens from stn CP235 were found to be in association with sunken wood, together with M. subchelata.

Remarks:
The present specimen has a pair of small blunt, granulate epigastric processes and four small spines on the anterior half of the lateral margin of the carapace. The anterolateral spine is distinct but the second to fourth spines are obsolescent and the fourth spine is situated at the end of the posterior cervical groove.  (Lovén, 1852), stn CD203, male (cl 7.7 mm); C, Munidopsis similior Baba, 1988, stn CP165, female (cl 9.1 mm); D, Munidopsis similior Baba, 1988 Macpherson (2007) suggested that the geographical distribution of this species should be reviewed as some of the previous records may belong to recently described species such as M. treis Ahyong andPoore, 2004 andM. ternaria Macpherson, 2007. The Taiwan specimen was collected at depths of 635-868 m. Baba, 1988 (Fig. 6C, D) Munidopsis similior Baba, 1988: 164, Fig. 65;Macpherson, 2007: 97, Fig. 55L.
Remarks: This species has strong rugosities on the carapace, and rippled rugae are present on the gastric region.

Munidopsis subchelata
Remarks: In the specimens examined, the P1 palm is long, subcylindrical, and 3.2-3.9 times as long as the dactylus.
The present specimens were found to be in association with sunken wood.

Remarks:
The specimens examined have the body and appendages covered with fine setae and the P1 palm unarmed on the mesial margin. These characters agree with the observations of the western Pacific material by Baba (1969Baba ( , 2005 and Macpherson (2007). Etymology: This specific name is derived from the Latin, tuberosus, full of humps, in reference to the body and pereopods entirely covered with tubercles and protuberances.
Description: Carapace (Fig. 7A, B), exclusive of rostrum, 1.1 times longer than broad; dorsal surface convex from side to side, covered with numerous, small protuberances bearing short setae (Fig. 7C); regions well delineated by furrows including distinct anterior and posterior cervical grooves, low but large swelling present behind posterior cervical groove. Epigastric lobes distinct, somewhat elevated, bordering base of rostrum. Posterior cardiac region subtriangular, strongly elevated, preceded by deep transverse depression. Posterior margin preceded by elevated ridge of small protuberances. Lateral margins subparallel, weakly convex, not crested; anterior corner unarmed, rounded; anterior end of anterior cervical groove and lateral end of posterior cervical groove each with very shallow notch. Frontal margin weakly concavely oblique behind ocular peduncle, leading to low, blunt external orbital angle, then transverse toward anterolateral corner of carapace. Rostrum (Fig. 7A, B) subtriangular in dorsal view, relatively narrow, 0.2 of breadth between anterolateral angles of carapace when measured dorsally at anterior bases of ocular peduncles, approximately 0.4 length of remaining carapace (postorbital carapace), horizontal in lateral view, terminating bluntly; lateral margins somewhat convex on median part; dorsal surface flattish, median longitudinal carina composed of small protuberances extending onto epigastric lobes; ventral surface with rounded longitudinal ridge in midline.
Sternal plastron as long as wide when measured along midline, maximum width at sternite 7. Sternite 3 (Fig. 7D) approximately 5.0 times as broad as long when measured along midline; anterior margin divided into 2 roundly triangular lobes by median notch; lateral margin of each lobe convex, with narrowly rounded projection anteriorly. Sternite 4 (Fig.  7D) not contiguous with and distant from posterior margin of sternite 3; greatest width 2.5 times that of sternite 3; anterior margins slightly oblique, each with row of small tubercles and setae; surface depressed in midline, with short setae. Sternites 5-7 each with row of setae on anterior ridge and scattered short setae on surface.
Basal article of antennular peduncle (Fig. 7F, G) with dorsolateral spine distinctly smaller than ventrolateral; ventrolateral spine with small marginal tubercles; lateral margin with small processes; distomesial margin with row of small tubercles but without dorsal spine; ventral surface with transverse protuberances.
Antennal peduncle (Fig. 7F) overreaching anterior margin of cornea by length of article 4. Article 1 with distomesial tuberculate process barely reaching distal margin of article 2; distolateral angle produced. Article 2 bearing blunt spine on each of distomesial and distolateral angles, distomesial spine smaller than distolateral; lateral margin tuberculate. Article 3 unarmed marginally or with minute distolateral spine, minute tubercles present on distal margin. Article 4 nearly smooth, with small distolateral spine.
Mxp 3 ischium (Fig. 7H) approximately as long as merus when measured on extensor margin; extensor margin with small distal spine; flexor margin sharply ridged, terminating in small spine; mesial ridge (crista dentata) with row of 19-21 small corneous teeth, proximal teeth reduced; lateral surface with small protuberances. Merus with small protuberances on lateral surface; flexor margin with 2 distinct spines on proximal half and several smaller spines; extensor margin with row of small spines, distal spine largest. Carpus with small blunt spines and tubercles on extensor surface. Propodus and dactylus nearly smooth. Exopod distinctly overreaching distal margin of merus. Epipod elongated.
Left P1 missing. Right Pl (Fig. 8A) moderately slender, 1.4 times longer than postorbital carapace (excluding rostrum); dorsal and ventral surfaces covered with numerous small protuberances bearing short setae; mesial surface of carpus and palm with some moderately long setae. Ischium unarmed. Merus 2.6 times as long as broad when measured along dorsodistal margin excluding spines, with rounded crest in dorsal midline; dorsomesial margin with strong distal spine; ventrolateral margin with small, blunt distal spine. Carpus 1.7 times longer than broad when measured along dorsodistal margin, unarmed. Palm relatively slender, moderately inflated, 1.1 times length of carpus, 1.6 times as long as broad when measured at bases of fingers; lateral margin somewhat concave at base of fixed finger. Fingers approximately as long as palm; opposable margins nearly straight, narrowly gaping, distally spooned; prehensile edges each with row of low, indistinct teeth, proximal teeth obsolete; distal margins each with row of small rounded or subtriangular teeth; fixed finger without denticulate carina on distolateral surface. P2-4 ( Fig. 8B-E) moderately slender, subcylindrical, somewhat compressed laterally, covered with protuberances; P4 shorter than P2 and P3; right P2 larger than left, not reaching tip of but barely reaching base of P1 fingers; dorsal and ventral margins with sparse, moderately long setae; protuberances with sparse short setae. Meri elongate, subrectangular in lateral view, each with row of protuberances on dorsal crest, distal protuberance pronounced; lateral surface, except rounded distal lobe, with numerous protuberances; ventrolateral margin with irregular rows of small protuberances, distally somewhat produced; mesial surface also with small protuberances, with broad rounded projection at ventrodistal end. Carpi each with irregular rows of protuberances on dorsal crest, distal protuberance pronounced; lateral surface with elevated crest of protuberances somewhat dorsally along midline and oblique row of pro- tuberances ventrally; ventral surface also with small protuberances; ventrodistal margin produced, protuberant but unarmed; mesial surface with small protuberances. Propodi, exclusive of distal rounded projection, 3.9-4.2 times as long as high when measured at base of distal projection; dorsal surface flattish, with small protuberances; dorsolateral and dorsomesial margins rounded, delimited by irregular row of protuberances; lateral surface with weakly elevated ridge of irregular protuberances in midline; ventral surface protuberant; ventrodistal margin with 2 small corneous spines, lateral spine larger than mesial; mesial surface with scattered small protuberances. Dactyli 0.6-0.7 length of propodi, each terminating in relatively short corneous claw (in left P2, shortened by regeneration); dorsal surface with small flattened protuberances; ventral margin nearly straight or weakly curved, with 8 or 9 low teeth deceasing in sizes proximally, each with slender corneous spine; lateral surface with small flattened protuberances; mesial surface with some small protuberances proximally. Epipods present on P1-3.

Remarks:
The new species appears close to M. granosicorium Williams and Baba, 1990 from Cascadia Basin of the eastern Pacific in having the carapace strongly tuberculate but lacking distinct spines on the dorsal surface and lateral margins, rostrum subtriangular and without distinct lateral spines, eye-spines absent, sternite 4 with anterior margins weakly oblique and not contiguous with the posterior margin of the sternite 3, abdomen unarmed, and epipods present on the P1-3. Munidopsis granosicorium is described on the basis of a single specimen lacking all pereopods. Nonetheless, M. tuberosa clearly differs from M. granosicorium in the carapace (excluding the rostrum) being longer than broad (as long as broad in M. granosicorium), a large swelling present behind the posterior cervical groove (no such structure in M. granosicorium), and the rostrum being much narrower and horizontal in lateral view (upwardly directed in M. granosicorium).

DISCUSSION
In the Indo-West Pacific, where extensive surveys of deep-sea decapod crustacean fauna have been made, 42 species of Munidopsis have been recorded from the western Indian Ocean, including the Red Sea, 27 from the Andaman Sea and the Bay of Bengal in the eastern Indian Ocean, 21 from Japan, 35 from the Philippines and Indonesia, 23 from the Solomon Islands, 17 from Australia, 15 from Vanuatu, 18 from New Caledonia, and 14 from Fiji (Baba, 2005;Cubelio et al., 2007a, b;Jones and Macpherson, 2007;Macpherson, 2007;Osawa and Takeda, 2007). The present study has increased the number of Munidopsis species from Taiwan to 31. The high number of species recorded reflects the recent intensive sampling efforts in the area. Since 2000, 375 deep-sea stations have been sampled around Taiwan, with 85 stations at depths between 1000 and 4455 m. Nevertheless, the many Munidopsis species found also indicate a particularly rich deep-sea fauna around Taiwan, an island only slightly bigger than New Caledonia and much smaller than the Philippines.
Of the 31 Munidopsis species in Taiwan, six were collected from abyssal depths below 3000 m: M. granosa, M. panamae, M. profunda, M. tafrii, M. teretis and M. echinata n. sp. The remaining 25 species were found at depths between 200 and 3000 m (Table 2) Species of Munidopsis are generally known to have a wide geographical distribution, assuming that current taxonomy is correct. Besides the two new species described above, M. latiangulata and M. sarissa are so far known only from Taiwan. As deep-sea benthic surveys are generally limited in the Indo-West Pacific, it is likely that some or all these four species will later be found in other waters. On the other hand, more species probably still await discovery in Taiwan. For example, M. antonii (Filhol, 1884), M. cylindropus Benedict, 1902 andM. subsquamosa Henderson, 1885 have been reported from both Japan and other Indo-West Pacific localities (Baba, 2005), but not yet from Taiwan. Further surveys are needed from the island as well as its adjacent waters for a better understanding of the character of the Taiwanese galatheid fauna.