Designation of a neotype for the dendrochirotid holothuroid, Thyone fusus (Mller) (Echinodermata: Holothuroidea: Dendrochirotida: Thyonidae).

The genus Thyone Oken, 1815 is complex, and has even been called a supergenus, which currently contains 67 nominal species (WoRMS, 2023) and is urgently in need of revision. This contribution provides an accurate description of the here designated neotype and as such, it brings clarity to the taxonomic definition of the type species of the genus: the previously poorly understood Thyone fusus.

A new species of dendrochirotid holothuroid from deep water of southern Japan, with the erection of a new genus, Satsumaocnus (Echinodermata: Holothuroidea: Dendrochirotida: Cucumariidae: Colochirinae).

A new dendrochirotid sea cucumber, Satsumaocnus kaiyomarui gen. nov., sp. nov. from deep water of southern Japan is herein described. The new species displays the following unique characters : a cylindrical, soft body; mouth surrounded by five oral valves; 10 equal, dendritic tentacles arranged in a single circle, each composed of two tufts; a low, stout, compact, calcareous ring without posterior prolongations; body wall ossicles comprising an external layer of small, x-framed hourglass-shaped cups originally described as "double-faced x-framed cup ossicles" in a previous study reported by Yamana et al. (2019), and an inner layer of scarce dendriform/branched rods, sometimes taking the shape of delicate plate-like deposits. Although the general (external and internal) morphological characters of the new species correspond well with the characters of species within the cucumariid subfamily Colochirinae Panning, 1949, our material lacks any buttons or elaborate plate-like ossicles which characterize all extant genera within this subfamily. We, therefore, describe our material as a new species S. kaiyomarui sp. nov. within the new genus Satsumaocnus. The predominant body wall deposits of the new species strongly resemble the hourglass type ossicles of some species of the psolid genus Lissothuria (Verrill, 1867), but differ in their possession of a supporting x-shaped frame. In addition, it is noteworthy that these hourglass deposits also resemble the table ossicles of some holothuriids and stichopodids, when viewed from the side, especially the small tables of some Labidodemas and/or Stichopus species, while the dendriform rods resemble those of Thelenota.

Nomenclatural changes in some sea cucumbers with the erection of a new genus and description of a Thyone ?juvenile (?n. sp.) from the Gulf of California (Echinodermata:Holothuroidea:Dendrochirotida).

This paper includes several nomenclatural changes in dendrochirotid holothuroids, mostly based on materials from the USNM. These include the erection of a new genus Pseudostolus for two Indo-Pacific Stolus species [(S. kilberti Rajpal Thandar, 1999 and S. rapax Koehler Vaney (1908)], re-assignment of Havelockia uniannulatus (Sluiter, 1914), Thyone pseudofusus Deichmann 1930, T. parafusus Deichmann, 1941 and T. axiologa H.L. Clark, 1938, to the genus Stolus, and re-assignment of Havelockia nozawai (Mitsukuri, 1912) and Thyone adinopoda Pawson Miller, 1981 to the genus Sclerothyone Thandar, 1989. In addition, a lectotype is designated for (T. vilis Sluiter, 1901), based on the study of type material at the ZMUA. The Caribbean Stolus cognatus is also described and commented on and a single, perhaps juvenile specimen from the Gulf of California is described as Thyone ? n. sp.

Multiple records and polymorphism of Parastichopus regalis (Cuvier, 1817) (Echinodermata: Holothuroidea: Stichopodidae) along the Algerian coast.

The family Stichopodidae is represented in the Mediterranean Sea by the genus Parastichopus which includes two non-endemic species; Parastichopus tremulus (Gunnerus, 1767) and Parastichopus regalis (Cuvier, 1817). On the Algerian coast (southwestern Mediterranean Sea), two morphotypes of P. regalis were observed, one with dark spots on the dorsal surface and the other non-spotted. In total, 65 individuals of P. regalis were recorded from 22 stations along the Algerian coast during an oceanographic campaign. Twelve individuals (6 of each morphotype) were used for a comparative study of the morphological (including endoskeletal) characteristics. Table ossicles, the only ossicles of the body wall of the two morphotypes of P. regalis, are here compared with regard to the disk diameter of the tables and the total area of the surface of the disc. Statistical analysis did not show any significant differences between the spotted and the non-spotted morphotypes.

On the taxonomic status of Holothuria (Holothuria) tubulosa (s.s.) from the Algerian coast with the description of a new Mediterranean species, Holothuria (Holothuria) algeriensis n. sp. (Echinodermata: Holothuroidea: Holothuriidae).

In this study we redescribe the taxonomy of some holothuriid species collected from different localities of the Algerian coastal waters. Morphological (anatomical and endoskeletal) and previous molecular studies show the presence of two distinct morphotypes of Holothuria (Holothuria) tubulosa "A" "B". Morphotype "A" corresponds to the classical Holothuria (Holothuria) tubulosa Gmelin 1791, described by Koehler (1921) and hereafter referred to as H. (H.) tubulosa (s.s.), while morphotype "B", we believe, represents a new species, herein named H. (Holothuria) algeriensis n. sp. with characteristics significantly different from those of Holothuria (H.) tubulosa (s.s.). Both morphology and statistical analysis (Linear Discriminant Analysis) confirm significant differences between these two morphotypes. To visualize these differences, measurements made on ossicles of Holothuria (H.) tubulosa (s.s.) and Holothuria (H.) algeriensis n. sp. were compared with other species present in our collections, including the north-eastern Atlantic and Mediterranean Holothuria (Roweothuria) arguinensis Koehler Vaney, 1906, recently recorded from Algerian waters, the Mediterranean Holothuria (Roweothuria) poli Delle Chiaje, 1824 and Holothuria (Holothuria) stellati Delle Chiaje, 1824. We conclude that the two morphotypes of H. (H.) tubulosa are significantly different to warrant the recognition of a new species, H. (H.) algeriensis n. sp. and the linear discriminant analysis (LDA) of the five species demonstrate this.

Paraleptopentacta, a new Mediterranean and north-west Atlantic sea cucumber genus, with the first record of P. tergestina n. comb. (Echinodermata: Dendrochirotida: Cucumariidae) from the north-western Algerian coast.

The genus Leptopentacta H.L. Clark, 1938 is here reviewed and restricted to include only the type species and related tropical Pacific forms, while a new genus Paraleptopentacta is erected to accommodate the Mediterranean and some north-west Atlantic species, formerly assigned to Leptopentacta. Paraleptopentacta n. gen. is characterized by a calcareous ring usually without posteriorly forked radial plates, in combination with body wall ossicles as an external layer of baskets (sometimes absent) and an inner layer of smooth (in one species knobbed), single-layered, multilocular plates, without a reticulum, as opposed to Leptopentacta H.L. Clark, 1938, which always has forked tails to the radial plates and ossicles as an external layer of rosettes and/or baskets and an inner layer of multi-layered or often reticulated scales/plates. A key separating both the genera and their species is provided. In addition, a first record of P. tergestina n. comb. (Sars, 1859), based on individuals collected as bycatch by a commercial benthic trawler in the Mostaganem region, north-west Algeria, is briefly described and its in vitro behavior noted.

Holothuria (Lessonothuria) insignis Ludwig, 1875 (formally resurrected from synonymy of H. pardalis Selenka, 1867) and Holothuria (Lessonothuria) lineata Ludwig, 1875-new additions to the sea cucumber fauna of Pakistan, with a key to the subgenus Lessonothuria Deichmann (Echinodermata: Holothuroidea).

Two specimens of a species herein identified as Holothuria (Lessonothuria) insignis Ludwig, 1875 and a single specimen identified as Holothuria (Lessonothuria) lineata Ludwig, 1875, were collected from the intertidal zone at low tide from two coastal localities in Karachi (Buleji and Sunahri). This paper briefly documents their morphology and habitat characteristics and formally resurrects H. (L.) insignis from the synonymy of H. (L.) pardalis Selenka, 1867, based on the observations of the ossicles assemblage deduced from current material, syntype, some material at the NHMUK (Natural History Museum,UK), and literature. H. pardalis is also commented on and compared with its related congeners in Pakistan, in tabular form. A key is presented of all species of the Lessonothuria group currently recognized in WoRMS.

On some lesser known sea cucumbers in the Natural History Museum, UK (Echinodermata: Holothuroidea).

A mixed batch of sea cucumbers tentatively labelled as ?Thyone or ?Havelockia species was obtained on loan from the Natural History Museum, United Kingdom (NHMUK) for identifications and records. The material dates back to 1850 and originates from shallow waters from various parts of the world. The material includes two new species and one new subspecies which have already been described in an earlier paper (see Thandar, 2017). The remaining specimens comprise a few known or poorly known nominal species and several indeterminate forms. This paper describes the known species while adding some useful information about them. Of the indeterminate species included are several specimens most belonging to the genus Thyone or Havelockia which, because of their incompleteness and absence of ossicles, are not identified beyond their suspected genus or species.

On some miscellaneous sea cucumbers (Echinodermata: Holothuroidea) in the collections of the South African Museum with three new species.

A miscellaneous collection of mostly small holothuroids, comprising some 140 specimens, received from the Iziko South African Museum (SAM), are here recorded and/or briefly described. Of these, one jar contained a badly mutilated holothuroid which was unidentifiable and hence not included here. The remaining material comprises 18 nominal species and an indeterminate elasipodid, perhaps representing a species of Benthodytes. Of the 18 nominal species, four are new to science, one of which has already been described as Trachythyone flaccida Thandar, 2013. Another, although represented by a single mature specimen from deep-water off the Transkei coast (Eastern Cape Province), is so different from its congeners that it is also described as a new species, Stereoderma mohammedi n. sp. Two other specimens, although juvenile, are so extraordinary in their composition of ossicles, that they are also taken to represent another new species, ?Temparena trouspetita n. sp. The collection also includes a single specimen of Synallactes, which together with a specimen misidentified as S. viridilimus by Thandar (2008), is also described as a new species, S. quatrami n. sp. The remaining species proved to be either new records for the southern African region or already well-known southern African forms whose distribution ranges have now changed.

The current status of Neocnus Arredondo, 1961 (Mammalia: Edentata: Pilosa: Megalonichidae) and a replacement name for its junior homonym in the sea cucumber family Cucumariidae (Echinodermata :Holothuroidea: Dendrochirotida: Cucumariidae).

This short communication addresses the problem associated with the current taxonomic status of the prehistoric edentate genus Neocnus Arredondo, 1961 (with type species Micronocnus gliriformis Matthew, 1931) which has long been considered a senior homonym of the dendrochirotid sea cucumber genus Neocnus Cherbonnier, 1972 (type species Neocnus incubans Cherbonnier, 1972) and replaces the latter (junior homonym) with Incubocnus n.g. The diagnosis of the new genus is the same as the cucumariid Neocnus as amended by O'Loughlin & O'Hara (1992). A brief history of the senior homonym Neocnus (Edentata) is given followed by a short literature survey dealing with its junior homonym.

Two new subfamilies, three new species and a new subspecies of dendrochirotid sea cucumbers (Echinodermata: Holothuroidea).

Some materials in the Natural History Museum, London, originating from various parts of the world, proved on examination, to comprise two new species herein described as Cladodactyla pesdispersa n. sp. and Thyonina rasidae n. sp., and a new subspecies, Havelockia ferali andamanensis n. subsp. In addition, some specimens examined from the museum collections of the Department of Aquatic Biology and Fisheries, University of Kerala in India contained, besides the well-known dendrochirotids, Aslia forbesi (Bell) and Stolus buccalis (Stimpson), two specimens which proved to also represent a new species of Thyonina, herein described as Thyonina bijui n. sp., as it differs significantly from T. rasidae n. sp. from Pakistan and the South African T. articulata Vaney. For the genus Thyonina, currently attributed to the subfamily Thyoninae, a new subfamily Thyonininae is here diagnosed. In addition a new subfamily Hemithyoninae is proposed for Hemithyone semperi (Bell), also placed in the Thyoninae till now.

A new genus and a new species in the sea cucumber subfamily Colochirinae (Echinodermata: Holothuroidea: Dendrochirotida: Cucumariidae) in the Mediterranean Sea.

A new genus Hemiocnus is here erected to accommodate the Mediterranean dendrochirotid sea cucumber Cladodactyla syracusana Grube, currently classified, with some doubt, in the cucumariid genus Pseudocnella. At the same time a new cucumariid species, Hemiocnus rubrobrunneus, is described from some Tunisian material, misidentified as Pseudocnella syracusana (Grube), received from the United States National Museum. The new genus appears most closely related to Pseudocnella than to any other genus within the Colochirinae. Although its body wall ossicles resemble those of Pseudocnella spp. it differs in that the two ventral-most tentacles are reduced and in the presence of rosettes in the tentacles. P. syracusana also cannot be classified in Ocnus because of the presence of multi-layered, fir-cone shaped plates in the body wall, often with one end denticulate; such ossicles are lacking in the type species of the latter genus. The new species, Hemiocnus rubrobrunneus, on the other hand, shows some resemblance to H. syracusanus in its characteristic buttons and incomplete baskets, differing in its softer body wall, lack of fir-cone-shaped plates and in the presence of rosettes and complete baskets in the body wall. There are also some resemblances of the new species to the Mediterranean species of Ocnus viz. O. brunneus, O. planci and O. lacteus, but the soft nature of the body wall, shallow quadrilocular instead of deep trilocular baskets, and the presence of large knobbed plates in the anal region precludes its inclusion in this genus.

Biodiversity and distribution of the southern African sea cucumbers (Echinodermata: Holothuroidea).

The history of the southern African holothuroid fauna south of the tropic of Capricorn, is updated and the biodiversity and distribution of the fauna discussed. All five currently recognized orders are represented, distributed over 24 families, 74 genera and 163 species. As many as 117 species are shelf forms comprising the following faunistic components : 36% Indo-Pacific, 12% West Indian Ocean, 1% Atlantic and 51% endemic. Four faunistic provinces are recognized : tropical Indo-Pacific Province on the east coast, extending to St Lucia in northern KwaZulu-Natal; the Subtropical (Natal) province, from this point to Port St. Johns in the Eastern Cape Province; the Warm Temperate (Agulhas) Province from this point to Cape Point in the Western Cape Province; and the Cold Temperate (Namaqua) from Cape Point to Walvis Bay in Namibia. Vertical distribution of the approximately 90 species collected from more than one locality is also given. The origin of the holothuroid fauna is briefly discussed and reiterated that the Indo-Pacific component moved in from the north mostly by way of the Mozambique-Agulhas Current. The origin of the endemic component is obscure but surmised that it is perhaps also of Indo-Pacific origin with negligible contribution from the Atlantic.

On some sea cucumbers (Echinodermata: Holothuroidea) from off the south and west coasts of South Africa collected by the South African Environmental and Observation Network (SAEON).

Twenty four specimens of holothuroids recently received from the South African Environmental and Observation Network (SAEON), collected from off the south and west coasts of South Africa, are herein recorded and/or described. The specimens comprise eight nominal and one indeterminate species and represent both shallow-water and deep-sea forms, distributed from Plettenberg Bay to just north of Lambert's Bay in the Western Cape Province. There are no new species but two new records for the South African region and extensions of horizontal and bathymetric distributions of the other species. Additions to the South African fauna are Zygothuria lactea (Théel, 1886) and Synallactes cf. challengeri (Théel, 1886). The paper also contains the first definite record of Thyone venusta Selenka, 1868, originally described from the Red Sea. Distribution ranges of the following species have been altered Synallactes viridilimus Cherbonnier, 1952; S. mollis Cherbonnier, 1952 and Psuedostichopus langeae Thandar, 2009.

On some sea cucumbers from Ghana (Echinodermata: Holothuroidea) with descriptions of a new genus and one new species.

This paper reports on some sea cucumbers (Holothuroidea) in the collections of the NHMUK, taken off the coast of Ghana. Most result from collections around Accra during the years 1949-52. A couple of other species are included. Altogether six species are here reported, viz. Holothuria (Holothuria) dakarensis Panning, 1939; Holothuria (Semperothuria) imitans Ludwig, 1875; Holothuria (Vaneyothuria) lentiginosa lentiginosa (von Marenzeller,1893); Stereoderma congoana (Heding, 1935); Ocnus cruciformis Thandar n. sp. and Leptopentacta cabindaensis (Cherbonnier, 1949) herein transferred to a new genus Cherbocnus Thandar erected for this purpose. Another West African species, Cladodactyla monodi Cherbonnier, 1950 is referred to Stereoderma. All cucumariids are West African forms whereas the holothuriids are shared with the North-West Atlantic Ocean.

Trachythyoneflaccida, a new sea cucumber species from southern Angola (Echinodermata:Holothuroidea:Dendrochirotida:Cucumariidae) with key to the genus.

A new species of a cucumariid holothuroid, Trachythyone flaccida, is described from shallow water off the southern coast of Angola. This increases to 20 the number of species in the genus Trachythyone. The new species is characterized by a soft, barrel-shaped body, scattered non-retractile tube feet, and body wall ossicles comprising a superficial layer of cup-like baskets and a deeper layer of simple, smooth, multilocular plates; cross-shaped deposits may also occur. The new species appears most closely related to the subantarctic T. bouvatensis (Ludwig & Heding, 1935) and to the Brazilian T. crassipeda Cherbonnier, 1965. A key is provided to all species currently classified in this genus.

A new species of Havelockia Pearson, 1903 from the Argentine Sea (Holothuroidea: Dendrochirotida: Sclerodactylidae).

Havelockia pegi sp. nov., is here described from shallow waters of the Argentine Sea. This new species is distinctive in the purple colouration of its tentacles, scarcity of body wall ossicles and the presence of rosette-shaped ossicles in both the introvert and the tentacles. It is not closely related to any of its congenors. This is the first record of a true sclerodactylid from Argentina. Thandarum hernandezi Martinez & Brogger, 2012, described in the family Sclerodactylidae, is now classified in the family Sclerothyonidae.