Parathyone braziliensis ( Verrill, 1868 )

Martins, Luciana & Tavares, Marcos, 2021, A new species of Parathyone (Holothuroidea: Dendrochirotida: Cucumariidae) from northeastern Brazil, with a key to species, Zootaxa 4985 (2), pp. 245-252 : 250-251

Parathyone braziliensis ( Verrill, 1868) vs Parathyone suspecta ( Ludwig, 1875)

Parathyone braziliensis was briefly described and poorly illustrated by Verrill (1868). Verrill established P. braziliensis (as Thyone (Sclerodactyla) braziliensis ) based on an uncertain number of specimens collected by C. F. Hart in different habitats and localities in southern Bahia, Brazil: “Occurs under dead corals in the shallow tide pools and holes in the reefs at the Albrolhos and elsewhere”.

No holotype was selected for P. braziliensis in Verrill’s description and, therefore, all his specimens are syntypes. According to Verrill (1868: p. 352), Hart’s collections were deposited at the Peabody Museum of Natural History, Yale University, but part stayed in C. F. Hart’s personal collection (it is unknown whether or not Verrill’s syntypes stayed with Hart). Verrill’s syntypes are no longer extant at the Peabody Museum. According to Dr. Eric Lazo-Wasem, Senior Collections Manager at the Peabody Museum (pers. com.), the non-type specimen “YPM 5391 Thyone braziliensis Verril , collected in 1876 and identified by A. E. Verrill is still preserved in the collections in Yale. This specimen, collected eight years after the original description of P. braziliensis in 1868, clearly cannot be part of Verrill’s syntypes.

Parathyone suspecta ( Ludwig, 1875) was described from Barbados and the holotype deposited at the Museum für Naturkunde (Berlim, Alemanha). The type of P. suspecta is no longer extant (Dr. Carsten Lüeter, curator of Marine invertebrates at the ZMB, pers. com.). Ludwig (1875) pointed out the strong morphological similarities between P. braziliensis and P. suspecta : “It’s probably true that the species is identical to Thyone braziliensis , but I can’t tell if it’s really the case with the rather flawed description that makes the inner anatomy almost entirely lost”.

Deichman (1930) regarded Parathyone braziliensis and P. suspecta as each other’s synonyms. However, neither Ludwig nor Deichmann examined specimens of P. braziliensis . The original description of P. suspecta Ludwig (1875) is of no help as it can apply equally well to both, P. braziliensis and P. suspecta .

Ancona-Lopez (1957), on the other hand, based on specimens of P. brazilienis (from Pernambuco, Brazil) and literature data alone for P. suspecta , considered the latter as distinct from P. braziliensis by having: 1) fusiform body (oval when contracted); 2) 10 tentacles, with the 2 more ventral smaller than the others; 3 soft skin; 4) grayish color; 5) pedicels small, numerous and irregularly arranged; 6) calcareous ring formed of 10 simple plates with posterior processes; and 7) ossicles variable in form, arranged according to the regions of the body. Clearly enough, all the above characters are found in both P. braziliensis and P. suspecta . Prata et al. (2020), based only on Brazilian specimens assigned to P. suspecta (Rio Grande do Norte, Paraíba and Bahia) and specimens of P. braziliensis (Rio Grande do Norte and Paraíba), uncritically accepted the distinguishing characters advanced by Ancona-Lopez (1957) without further discussion (due to the availability of comparative material and lack of information, especially regarding the variation and structure of the dermal ossicles and calcareous ring).

However, we have studied topotypical specimens of both P. braziliensis and P. suspecta (see under comparative material examined) and found that the purported distinguishing characters advanced by Ancona-Lopez (1957) and accepted by Prata et al. (2020) are variable and of no help to separate P. braziliensis from P. suspecta . In the absence of consistent morphological characters to confidently separate the two species we, therefore, provisionally consider P. braziliensis and P. suspecta each other’s synonyms until further evidence is available, with the priority being for P. braziliensis (contrary to Deichmann, 1930, who mistakenly gave the priority to P. suspecta ).