Claude Massin

Epifaunal inventory of two shipwrecks from the Belgian Continental Shelf

Shipwrecks are almost the only subtidal substrata available for epifaunal colonization along the Belgian coastal waters and have never been scientifically prospected up to now. Two shipwrecks have been investigated during the summers of 2001 and 2002. De-visu observations and examination of 14 scraped surfaces of 0.0625 m2 allowed the identification of a total of 121 macrofauna species. Species richness cumulative curves provide an estimated number of 150–280 species. Both shipwrecks are dominated by Cnidarians. The tube-dwelling amphipod Jassa herdmani was also particularly abundant. Striking differences were observed between shipwrecks. Different faunal assemblages were observed on vertical and horizontal surfaces. Species richness could not been correlated with diversity indices. Samples with high species diversity were observed when the Hydrozoan Tubularia indivisa was dominant. On the contrary, when the Anthozoan Metridium senile was dominant, samples showed a very low species richness. Finally, the Poriferan Dysidea fragilis has to be considered as a new species for the Belgian fauna.

The holothurian subgenus Mertensiothuria (Aspidochirotida: Holothuriidae) revisited

Mertensiothuria is one of the 20 subgenera currently recognized under Holothuria. The diagnosis of the subgenus is amended with new information on the ossicles found in the longitudinal muscles. The number of species of Mertensiothuria considered to be valid at present is six. These species are redescribed on the basis of new material, type and non-type museum material and on re-evaluation of literature. Two of them, Holothuria hilla and Holothuria aphanes, are transferred from the subgenus Thymiosycia to Mertensiothuria. Four species formerly referred to Mertensiothuria are removed; provisionally they are not referred to any of the known subgenera of Holothuria. Full annotated descriptions or (where the type material was not available) references to the literature are given for each species. An identification key is given to the species belonging to the subgenus Mertensiothuria.

The genus Labidodemas (Holothuroidea: Aspidochirotida) revisited, with description of three new species and with re-positioning of Holothuria (Irenothuria) maccullochi Deichmann, 1958

Prior to the present revision the taxon Labidodemas comprised Labidodemas americanum, L. pertinax, L. rugosum and L. semperianum. An up-to-date re-evaluation of the group proved that at least four additional species need to be assigned to it. Three of these are new to science: one has recently been discovered in the shallow waters of KwaZulu-Natal, Republic of South Africa; one originates from Low Island, Australia, and was erroneously identified as L. semperianum, and one stems from South-West Sulawesi, again erroneously identified as L. semperianum. In addition, Holothuria maccullochi, classified in the monotypic subgenus Irenothuria, and Holothuria proceraspina are assigned to Labidodemas; the former as a valid species and the latter as a synonym of L. semperianum. Annotated taxonomic descriptions, distribution maps and an identification key are given. The new observation that L. americanum possesses Cuvierian tubules suggests that its rank remains at generic level rather than at family level as was recently proposed.

Holothuria (Selenkothuria) parvispinea n. sp. (Echinodermata, Hololthuroidea, Holothuriidae) with key to the sub-genus Selenkothuria

Description of a new species from Australia, belonging to the subgenus Selenkothuria (Holothuria, Aspidochirotida). A dichotomous key of the thirteen valid species included in the subgenus is also given. The species H. perrieri Thandar, 1977 and H. spinea Cherbonnier, 1988 are considered as non valid.