Tunisia occupies a strategic biogeographic position in the Mediterranean Sea and the Strait of Sicily is considered a biogeographical boundary that separates the eastern and western basins. Despite the importance of marine biodiversity in Tunisia, the few studies of Echinodermata fauna in this region data from long ago. In order to update and produce a validated checklist of the echinoderms that occur in northern Tunisia, a study of this phylum was carried out between 2012 and 2016. Forty-five species were inventoried and distributed into the five living Echinodermata classes (Crinoidea, Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea). New occurrences of four species from Tunisian marine waters [
Túnez ocupa un área biogeográfica estratégica en el Mediterráneo. El estrecho tunecino-siciliano es considerado una frontera biogeográfica que separa las cubetas oriental y occidental. Sin embargo, a pesar de su interés, los estudios sobre la fauna de equinodermos de Túnez son antiguos y escasos. Con el fin de elaborar el inventario de los equinodermos de la región septentrional del mar de Túnez, se realizó un estudio de este filum entre los años 2012 y 2016. Se han inventariado cuarenta y cinco especies pertenecientes a las cinco clases actuales de Echinodermata (Crinoidea, Asteroidea, Ophiuroidea, Echinoidea y Holothuroidea). Cuatro especies [
Tunisia occupies a central position between the western and eastern Mediterranean Sea. It is the northernmost point of the African continent (36°347′N, 9°129′E). The Strait of Sicily, from Cape Bon (northeastern Tunisia) to Mazara dell Vallo (Sicily, southern Italy), has been considered a biogeographical barrier that separates the eastern and western Mediterranean basins (
The phylum Echinodermata includes marine invertebrate species and is composed of five living classes: Crinoidea, Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea. They cover a wide range of biological strategies, habitats and depths. Echinoderms are found from the shallow intertidal to the abyssal zone, where they play an important role in the ecological processes of marine ecosystems.
Lack of research on Echinodermata is a knowledge gap regarding Tunisian marine biodiversity. Only two studies, by
In order to update the inventory of marine diversity of Echinodermata species in the Tunisian Sea, research was performed between 2012 and 2016. The acquired data were used to produce a validated checklist of the Echinodermata of northern Tunisia.
Echinoderms were sampled at 93 sites in eight locations along the northern coasts of Tunisia (Supplementary material Table S1). The study area extends over 300 km of the Tunisian coastline, from the Algerian-Tunisian border (37°01′06.0″N, 8°44′04.5″E) to the Cape Bon Peninsula (36°26′53.1″N 10°51′36.5″E). (
This area of the central Mediterranean Sea is constantly affected by incoming Atlantic marine currents (
The Echinodermata inventory was carried out from March 2012 to July 2016. A variety of sampling strategies were adopted depending on the substrate type (rocky or soft bottom, depth) and respecting the benthic bionomics of the Mediterranean Sea (
Taxa | Distribution | Depth range (m) | Habitat | Abundance | Location (L) |
---|---|---|---|---|---|
Class CRINOIDEA | |||||
Family Antedonidae | |||||
Antedon bifida (Pennant, 1777) | M, A | 50-190 | S, M, R | 50 | 1, 2, 8 |
Antedon mediterranea (Lamarck, 1816) | ME | 50-190 | S, M, R | 68 | 1, 2, 8 |
Leptometra phalangium (Müller, 1841) | M, A | 72-194 | S, M | 33 | 1, 8 |
Class ASTREROIDEA | |||||
Family Asteriidae | |||||
Coscinasterias tenuispina (Lamarck, 1816) | M, A | 20-51 | S | 2 | 2, 8 |
Marthasterias glacialis (Linnaeus, 1758) | M, A | 75-220 | S, M, R | 11 | 2, 8 |
Family Asterinidae | |||||
Anseropoda placenta (Pennant, 1777) | M, A | 185-220 | S | 1 | 8 |
Asterina gibbosa (Pennant, 1777) | M, A | 0.45-0.65 | R, A | 13 | 3, 5 |
Asterina pancerii (Gasco, 1876) * | ME | 3-5 | Cy | 3 | 4 |
Family Astropectinidae | |||||
Astropecten aranciacus (Linnaeus, 1758) | M, A | 51-177 | S, M | 24 | 2, 8 |
Astropecten bispinosus (Otto, 1823) | M, A | 1-35 | S, M | 11 | 2, 3, 4 |
Astropecten irregularis (Pennant, 1777) | M, A | 50-220 | S | 33 | 1, 2, 8 |
Astropecten jonstoni (Delle Chiaje, 1827) | ME | 3-5 | S | 1 | 4 |
Tethyaster subinermis (Philippi, 1837) | M, A | 50-220 | S, M | 39 | 1, 2, 8 |
Family Chaetasteridae | |||||
Chaetaster longipes (Retzius, 1805) | M, A | 70-170 | S, M | 21 | 1, 2, 8 |
Family Echinasteridae | |||||
Echinaster (Echinaster) sepositus (Retzius, 1783) | M, A | 3-220 | S, M, R | 96 | 1, 2, 8 |
Family Luidiidae | |||||
Luidia atlantidea Madsen, 1950 * | A | 65-95 | S | 1 | 8 |
Luidia sarsii sarsii Düben and Koren in Düben, 1844 | M, A | 175-193 | M | 1 | 1 |
Family Ophidiasteridae | |||||
Hacelia attenuata Gray, 1840 | M, A | 70-85 | R | 1 | 1 |
Class OPHIUROIDEA | |||||
Family Amphiuridae | |||||
Amphipholis squamata (Delle Chiaje, 1828) | C | 0.4-0.6 | A | 16 | 5 |
Family Gorgonocephalidae | |||||
Astrospartus mediterraneus (Risso, 1826) | M, A | 98-105 | S | 2 | 8 |
Family Ophiacanthidae | |||||
Ophiacantha setosa (Bruzelius, 1805) | M, A | 70-165 | G | 54 | 1 |
Family Ophiactidae | |||||
Ophiactis savignyi (Müller and Troschel, 1842) | C | 3-5 | S | 1 | 5 |
Ophiactis virens (M. Sars, 1859) * | M, A | 0.4-0.6 | A | 184 | 5 |
Family Ophiocomidae | |||||
Ophiocomina nigra (Abildgaard in O.F. Müller, 1789) | M, A | 50-58 | M | 1 | 2 |
Family Ophiodermatidae | |||||
Ophioderma longicauda (Bruzelius, 1805) | M, A | 0.65 | R, A | 1 | 7 |
Family Ophiomyxidae | |||||
Ophiomyxa pentagona (Lamarck, 1816) | M, A | 50-210 | S, M, R | 81 | 2, 8 |
Family Ophiotrichidae | |||||
Ophiothrix quinquemaculata (Delle Chiaje, 1828) | ME | 72-175 | S, M, R | 21 | 2 |
Family Ophiuridae | |||||
Ophiura ophiura (Linnaeus, 1758) | M, A | 3-194 | S, M, R | 124 | 1, 2, 4, 8 |
Class ECHINOIDEA | |||||
Family Arbaciidae | |||||
Arbacia lixula (Linnaeus, 1758) | M, A | 0.25-5 | S, R | 12 | 1, 2, 7 |
Family Cidaroidae | |||||
Cidaris cidaris (Linnaeus, 1758) | M, A | 50-220 | S, M, R | 114 | 1, 2, 8 |
Stylocidaris affinis (Mortensen, 1909) | C | 50-220 | S, M, R | 114 | 1, 2, 8 |
Family Diadematidae | |||||
Centrostephanus longispinus (Philippi, 1845) | M, A | 50-220 | S, M | 74 | 2, 8 |
Family Echinidae | |||||
Gracilechinus acutus Lamarck, 1816 | M, A | 50-125 | S, R | 18 | 8 |
Family Parechinidae | |||||
Paracentrotus lividus (Lamarck, 1816) | M, A | 0.2-6 | S, R | 48 | 1, 2, 7 |
Family Spatangidae | |||||
Spatangus purpureus (O.F. Müller, 1776) | M, A | 3-5 | S | 1 | 8 |
Family Toxopneustidae | |||||
Sphaerechinus granularis (Lamarck, 1816) | M, A | 0.6-5 | R, A | 2 | 7 |
Class HOLOTHUROIDEA | |||||
Family Cucumariidae | |||||
Hemiocnus syracusanus (Grube, 1840) | M | 3-5 | S | 1 | 4 |
Leptopentacta elongata (Düben and Koren, 1846) | M, A | 77-145 | S | 1 | 8 |
Leptopentacta tergestina (M. Sars, 1857) * | ME | 77-145 | S | 3 | 8 |
Family Holothuriidae | |||||
Holothuria (Holothuria) mammata Grube, 1840 | ME | 3-8 | S, R, A | 2 | |
Holothuria (Holothuria) tubulosa Gmelin, 1791 | M, A, R | 0.2-185 | S, M, R, A | 40 | 1, 2, 7 |
Holothuria (Platyperona) sanctori Delle Chiage, 1823 | M, A, R | 0.2-0.4 | R, A | 8 | 7 |
Holothuria (Roweothuria) poli Delle Chiaje, 1824 | M, A, R | 0.2-8 | S, R, A | 16 | 2, 7 |
Holothuria (Thymiosycia) impatiens (Forsskål, 1775) | C | 0.45 | R | 1 | 6 |
Family Stichopodidae | |||||
Parastichopus regalis (Cuvier, 1817) | M, A | 0.2-194 | S, M, R | 58 | 1.8 |
The collected material was measured, photographed and preserved in ethanol. Specimens were identified based on external morphology and internal anatomy following the taxonomic criteria of
Samples of the collected martial are deposited in the zoology collection of the University of Murcia (UMCZ).
Forty-five echinoderm species were collected and identified in northern Tunisia waters (
All the inventoried species are present in the Mediterranean Sea, except for the starfish-
Six of the collected species are endemic in the Mediterranean Sea, namely:
Four collected species were first records for Tunisia:
The new species recorded for the first time in the present work (
Class ASTEROIDEA Blainville, 1830
Order VALVATIDA Perrier, 1884
Family ASTERINIDAE Gray, 1840
Genus
Order PAXILLOSIDA Perrier, 1884
Family LUIDIIDAE Sladen, 1889
Genus
Class OPHIUROIDEA Gray, 1840
Order OPHIURIDA Müller and Troschel, 1840
Family OPHIACTIDAE Matsumoto, 1915
Genus
Class HOLOTHUROIDEA Brin, 1860
Order DENDROCHIROTIDA Grube, 1840
Family CUCUMARIIDAE Ludwig, 1894
Genus
Molecular study
Genetic analysis identified the doubtful specimens of the genus
Clade II, comprising the outgroup species
The K2P distances, based on COI sequences, are shown in
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|
|
|
|
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- | |||||
0.209 | - | ||||
0.165 | 0.223 | - | |||
0.092 | 0.192 | 0.157 | - | ||
0.260 | 0.189 | 0.259 | 0.249 | - |
The Asteroidea are characterized by two new findings:
A single
We report new findings of the ophiuroid
Holothuroidea is represented by one new record for the Tunisian Sea:
Two species of the Ophiuroidea class,
The echinoderms recorded from northern Tunisian marine water in this study are quite diverse (45 species). Among the recorded groups, Asteroidea were the most diverse, with 15 species, followed by Ophiuroidea (10 species), Holothuroidea (9), Echinoidea (8) and Crinoidea (3). This can be explained by the techniques and gears used to sample them (hand collection, dredging, trawling and diving). Accordingly, the present research method increased the collection area by covering the marine benthic zones of the Mediterranean Sea, from the infralittoral level to the bathyal level.
Most of the new recorded species (
A review of the relevant literature of megabenthic Tunisian inventories, including the Echinodermata phylum, by
Northern Tunisia alone (from the Algerian-Tunisian border to Ras Kapudia) showed the highest number, with 69 species against 61 in the south (from Ras Kapudia to the Libyan border, including the Gulf of Gabès). However, some species present in the northern part are absent in the south and vice versa (
Little research has been done on Echinodermata in deep Mediterranean waters (
Echinodermata marine biodiversity along the Algerian coast, from the Moroccan border to the Tunisian border, is very low compared with that in northern Tunisia, with 48 species being recorded in Algeria (
These findings confirm the importance of northern Tunisia area, which emerging a large number of exotic marine species and a high rate of endemic species (
Overall, the present work enhances the importance of the studied fauna in northern Tunisia. To maintain the diversity of echinoderms in Tunisia’s marine waters, it is necessary to promote efforts and acquire knowledge about this macrobenthic group by involving southern and eastern Tunisia.
Systematic studies based on taxonomical and anatomical criteria have often been confusing and doubtful because of the large morphological similarity between species. Many authors have been involved in research on systematic identification and/or revision of the taxonomical status of different classes of Echinodermata and have provided molecular evidence to support their findings (
For the class Holothuroidea,
As regards our doubtful species,
In addition, the present study points to great morphological and molecular similarities between sea cucumbers from the Atlantic Ocean and the Mediterranean Sea. They were all characterized by elongated and twisted buttons. However, these characteristics are very common in
Though spicule morphology is an effective taxonomic character, it may show some overlap in some genera, such as the
At present, the systematic position of the sea cucumbers of the genus
Special thanks are due to the fishermen for their help during the sampling along the northern coast of Tunisia. We express our sincere gratitude to Helena Ibáñez from the Department of Ecology and Hydrology (University of Murcia) and Alejandro López-López and José Galián from the Department of Zoology and Physical Anthropology (University of Murcia) for their help and advice on molecular analyses. We also thank the journal editor and two anonymous referees for their constructive criticism on an earlier version of this paper.
The following supplementary material is available through the online version of this article and at the following link:
Table S1. – Collection sites and sampling methods of the echinoderms from different localities of northern Tunisia.
Table S2. – Samples name’s and diameters. With the habitat type, depth (maximum and minimum) and date of collection of each sample.