onchidiid, Rafinesque, 1815

Dayrat, Benoît, 2009, Review of the current knowledge of the systematics of Onchidiidae (Mollusca: Gastropoda: Pulmonata) with a checklist of nominal species, Zootaxa 2068 (1), pp. 1-26 : 7-21

History of onchidiid species-group names

One hundred and fifty-one names are listed below, two of which are variety names . One name is a nomen nudum: Onchidium laevigatum Cuvier, 1817 . Four names refer to species that do not belong to onchidiids: Onchidium cubense Pfeiffer, 1840 , and Onchidium occidentale Guilding, 1825 refer to veronicellids; Buchanania onchioides Lesson, 1826 refers to a fissurellid; Onchidium sloanii Cuvier, 1817 is a problematic name that might refer to a lizard. Finally, three names are obvious spelling mistakes, i.e., names attributed to authors who did not create such names: Blainville (1825a) erroneously attributed authorship of Peronia laevis to Quoy and Gaimard, but Peronia laevis likely corresponds to Onchidium vaigiense Quoy and Gaimard, 1824 ; Blainville (1825a) erroneously attributed authorship of Peronia semituberculata to Quoy and Gaimard, but Peronia semituberculata likely corresponds to Onchidium planatum Quoy and Gaimard, 1824 ; Gray (1850) erroneously attributed authorship of Onchidella nigra to Lesson, but Onchidella nigra likely corresponds to Onchidium ater Lesson, 1830 . So, overall, 141 species names (and two variety names ) are available in Onchidiidae .

Most of those names (92 out of 143) were created before 1900 (20 names before 1850, 19 between 1850 and 1880, and 53 between 1880 and 1900); 40 names were created between 1900 and 1935; and only 11 names were created since 1935 (including only three after 1980). The small number of species described in the last 70 years does not indicate that there are no new species of onchidiids to be discovered. Rather, it indicates that nomenclatural confusion (i.e., the nomenclatural status of existing names unknown) has prevented people from working on this taxon and describing new species.

Geographic distribution

Information on type localities is critical in systematic revisions. A list of all type localities is provided below, organized by biogeographic region. In the vast majority of the cases, type localities were not designated in original descriptions, mainly because most species were described many decades ago. Thus , type localities may include several localities unless a single type locality was subsequently selected: Onchidium ambiguum was originally described from Palau and Singapore and no type locality was subsequently designated, so both Palau and Singapore are type localities; Peronia peronii was first described from Mauritius and Timor, but Hoffmann (1928) selected Mauritius as the type locality. In the list below, species for which there exist more than one type locality are indicated by an asterisk (*) following the species name.

One of the most interesting aspects of the geographic distribution of Onchidiidae is that only Onchidella and Hoffmannola are found outside the tropical Indo-West Pacific ( Hoffmannola is restricted to the tropical eastern Pacific, and Onchidella has an extensive distribution globally but is not found in tropical Indo-West Pacific), whereas all other genera are exclusively found in tropical and subtropical Indo-West Pacific. Interestingly, three species of Onchidella are found in the temperate waters of Japan ( O. kurodai , O. orientalis ) and New South Wales ( O. reticulata ), but no Onchidella species was described from the tropical Indo-West Pacific, at least if Labbé’s classification is adopted. Hoffmann (1929) attempted to use Wegener’s plate tectonics theory to explain the discrete distribution of Onchidella and other onchidiids (12 genera exclusively present in tropical Indo-West Pacific and Onchidella and Hoffmannola found in the rest of the world but not in tropical Indo-West Pacific). Although Hoffmann’s scenarios suffered from lacking a rigorous onchidiid phylogeny, his work was one of the first studies trying to link plate tectonics and biogeography.

Because the supra-specific relationships of onchidiids are largely unknown, we cannot reconstruct how this distribution was put in place during the evolutionary history of onchidiids. Nonetheless, onchidiids constitute a potentially good model for addressing broad questions of historical biogeography and distribution patterns. Several interesting questions will need to be addressed, such as: Is Onchidella the oldest group? Is the radiation of Indo-West Pacific onchidiids more recent? Did Onchidella emerge from an older non- Onchidella Indo-West Pacific taxon? What might have caused a split between Onchidella (+ Hoffmannola ) and all other onchidiid taxa? Is this distributional split real or an artifact of our current supra-specific taxonomy? Those questions can only be addressed in a phylogenetic context, especially because current genera may or may not be monophyletic.

Type locality unknown. ― Onchidella oniscioides , Onchidium hardwickii , O. multiradiatum , O. trapezoidum , Paraoncidium ovale , Peronia alderi , Semperoncis huberti .

European eastern Atlantic & Mediterranean. ― Onchidella celtica , O. tuberculata , O. nana , O. parthenopeia , O. remanei .

Western Africa. ― Onchidella accrensis , O. maculata , O. monodi , O. pachyderma , O. philippei , O. souriei .

South Atlantic. ― Ascension Island: Onchidella incisa .

Western Atlantic. ― Bermuda: Onchidella transatlantica . ― Brazil: O. indolens .

Caribbean. ― Caribbean Islands: Onchidella armadilla , O. miusha , O. schrammi . ― Florida: O. brattstoemi , O. floridana , O. wah .

Eastern Pacific. ― Northeastern Pacific: Onchidella borealis , O. carpenteri . ― Gulf of California: O. binneyi , Hoffmannola hansi . ― Ecuador & Panama: O. hildae . ― Galapagos: H. lesliei , O. steindachneri .

Southeastern Pacific. ― Chile: Onchidella chilense , O. coquimbensis , O. juan-fernandeziana , O. lanuginosa .

Tierra del Fuego. ― Onchidella marginata

Southwestern Pacific. ― New Zealand: Onchidella campbelli , O. flavescens , O. irrorata , O. nigricans , O. obscura , O. patelloide , O. reticulata *.

Northwestern Pacific. ― Japan: Onchidella kurodai , O. orientalis .

South Africa. ― Onchidium burnupi , Onchidella capensis , O. pulchella .

Tropical and subtropical Indo-West Pacific. ― Red Sea: Onchidium durum , Paraperonia gondwanae *, P. jousseaumei , Peronia anomala , and possibly P. savignyi * and P. verruculata . ― Djibouti: Peronia gaimardi *, Scaphis gravieri *. ― Eastern Africa : Onchidina australis *, Scaphis gravieri *. ― Madagascar: Paraperonia madagascariensis . ― Comoro Islands: Scaphis gravieri *. ― Mauritius: Paraperonia gondwanae *, Peronia mauritiana , P. peronii * (type locality). ― Indian Ocean: Onchidium steenstrupii *, Paraoncidium nangkauriense , P. simrothi , Quoyella indica . ― India: Onchidium pallidum , O. tenerum , O. tigrinum , O. typhae , Paraperonia gondwanae *, Peronina alta . ― Burma: Onchidium pallidipes , Platevindex inspectabilis . ― Thailand: Labella ajuthiae . ― Malaysia: Platevindex coriaceum *. ― Singapore: Onchidium aberrans , O. ambiguum *, O. griseo-fuscum , Platevindex coriaceum *, P. luteum , P. martensi . ― Vietnam: Onchidium harmandianum , Platevindex condoriana ,

Scaphis lata , S. tonkinensis . ― Hong Kong: Onchidium hongkongensis , Platevindex mortoni . ― China: Paraoncidium reevesii *. ― Philippines: Onchidium gracile , O. multinotatum , O. samarense , Paraoncidium graniferum , Peronia branchifera , Platevindex apoikistes , P. coriaceum *, P. semperi , Semperoncis glabrum . ― Guam: Onchidium planatum . ― Palau: Onchidium ambiguum *, O. nebulosum , Paraoncidium palaense . ― Micronesia: Onchidium steenstrupi *. ― Borneo: Onchidium nigrum , Platevindex ponsonbyi , P. stuxbergi . ― Indonesia: Lessonina ferruginea , Onchidium applanatum , O. elberti , O. mertoni , O. tabularis , O. tricolor , Paraoncidium keiense , P. vaigiense , Platevindex amboinae , P. coeca , Scaphis astridae , S. ater , S. punctata , S. straelenii . ― Timor: Peronia peronii *. ― New Guinea: Onchidium lixii , O. steenstrupii *, Paraoncidium papuanum . ― Papua New Guinea: Onchidium marmoratum , Platevindex granulosum , P. lata , P. schneideri . ― Torres Strait: Paraperonia gondwanae *, Scaphis viridis . ― Australia (Queensland): Onchidina australis *, Onchidium tumidum , Paraoncidium buetschlii , P. fungiforme , P. meriakrii , Platevindex coriaceum *. ― Australia (New South Wales): Onchidella reticulata *, Onchidium daemelii , Paraoncidium chameleon . ― Australia (Western Australia): Platevindex cinerea . ― Solomon Islands: Peronia gaimardi *. ― New Caledonia: Onchidina guineensis , Scaphis carbonaria . ― Fiji: Onchidina acinosa , Onchidina australis *, Paraperonia fidjiensis , Peronia corpulenta , P. melanopneumon . ― Tonga: Onchidium cinereum , Peronia tongana . ― Polynesia: Onchidium griseum , O. platei .