Tetralia glaberrima (Herbst, 1790)

PETER CASTRO, PETER K. L. NG & SHANE T. AHYONG, 2004, Phylogeny and systematics of the Trapeziidae Miers, 1886 (Crustacea: Brachyura), with the description of a new family, Zootaxa 643, pp. 1-70 : 26-29

Tetralia glaberrima (Herbst, 1790) (Plate 1D, E, 2A)

Cancer glaberrimus Herbst, 1790: 262 , pl. 20, fig. 115 (colour) (see Plate 2C).

Trapezia integra Latreille, 1828: 696 .

Trapezia serratifrons Jacquinot, in Hombron & Jacquinot 1846 : pl. 4, fig. 20 (colour)—23; Jacquinot, in Lucas 1853: 47.

Tetralia laevissima Stimpson,1858: 38 [35]; Stimpson 1907: 73, pl. 9, figs. 4, 4a.

Tetralia glaberrima forma fulva Patton, 1966: 286 (invalid name)

Tetralia glaberrima fulva Serène, 1984: 282 .

Tetralia sanguineomaculata Galil & Clark, 1990: 375 , figs. 4, 5, 6b.

Remarks. The taxonomic history of Cancer glaberrimus Herbst, 1790 , has been very confusing. In recent times, the name has been used loosely for a number of species of Tetralia , and despite the several revisions and taxonomic studies (including the establishment of a separate genus Tetraloides ) by several authors, the exact identity of T. glaberrima has never been discussed. This is all the more unfortunate and surprising since Cancer glaberrimus is the type species of Tetralia . In fact, as late as 1918, Rathbun (1918: 254) regarded Cancer glaberrimus as a junior synonym of the grapsid Planes minutus ( Linnaeus, 1758) !

Unfortunately, only its colour provides a clue to the identity of C. glaberrimus . The smooth carapace was described as brown with a bluish colour that gave it a porcelain­like shine (" porzellanähnliches Ansehen "; Herbst 1790: 262). A colour figure (Herbst 1790: pl. 20, fig. 115) shows a large, blue spot centered on the anterior half of the carapace (Plate 2A). The spot surrounds a smaller, round spot of the same colour, perhaps a hole on the carapace. No such colour pattern has ever been observed or described in any trapeziid so it is most probably an artefact. A blue band across the frontal margin of the carapace has been described in T. cinctipes Paulson, 1875 , but this is evident only on live specimens ( Castro 1997b: pl. 1, fig. A [colour]), something Herbst most probably could not observe. A uniform brown colour without black or dark brown bands agrees best with the colour pattern of T. fulva Serène, 1984 (see Castro 1997a: 67, pl. 1, fig. C [colour]). As such, on the basis of the available information, Cancer glaberrimus can be referred to either T. cinctipes Paulson, 1875 , or T. fulva Serène, 1984 . However, we believe that in the interests of nomenclatural stability, C. glaberrimus and T. fulva should be regarded as synonymous (see below). The type locality of C. glaberrimus was stated as unknown, although it was probably obtained from the Indian Ocean as much of his material was from there (see Ng 1996, Sakai 1999). There are no extant type (s). The first two authors have searched in vain for the types on separate occasions over the last decade, and Sakai (1999: 41) also recorded that it was lost. This has also been confirmed by the former and present crustacean curators of the Zoologisch Museum, Humboldt­Universität, Berlin, Hans Gruner and Oliver Coleman respectively (pers. comm.).

The identity of Trapezia integra Latreille, 1828 , is also a mystery. There is no type material in the Muséum national d’Histoire naturelle, Paris. The species was described from an unknown location and it was seemingly a new or replacement name for Cancer glaberrimus ( Latreille 1828: 696) . As such, Trapezia integra Latreille, 1828 , shares the same type series as Cancer glaberrimus Herbst, 1790 .

Castro (1997b) suggested that T. serratifrons Jacquinot, 1846 (type locality Marquesas Islands, French Polynesia) is likely to be conspecific with T. fulva Serène, 1984 . It is here regarded as a junior synonym of T. glaberrima . The colour figure of T. serratifrons (which shows a brown carapace without dark bands) is diagnostic for T. glaberrima (as T. fulva ). No type material of this species (supposedly in the MNHN) exists.

Tetralia laevissima Stimpson, 1858 , described from southern Japan, is very likely to be a junior synonym of T. glaberrima as well. Although Stimpson’s type material is no longer extant, the drawings, presumably made by Stimpson himself or under his supervision ( Stimpson, 1907: pl. 9, figs. 4, 4a), do not show any distinctive, obvious colour pattern on the carapace, chelipeds, or ambulatory legs. This is diagnostic for T. fulva (sensu Galil 1988a: fig. 1b; Castro 1997a: pl. 1, fig. C [colour]) (= present T. glaberrima ), which is uniformly brown to tan except a thin orange to red­orange line along the anterior border of the carapace and along the distal margins of carpi and anterior margins of meri of chelipeds. The ambulatory legs are uniformly brown to tan except a black spot on the articulations of the carpi visible in most specimens. We doubt that Stimpson would have missed a characteristic colour pattern such as a wide band along the anterior portion of the carapace (if present) in his figure of the species, especially since he clearly indicated the honeycomb­like network of lines in his drawing of the carapace of Trapezia septata ( Stimpson 1907: pl. 9, fig. 5, as Trapezia reticulata Stimpson, 1858 ). The chelipeds of T. laevissima were described as "glossy", which also agree with those of T. fulva . In T. cinctipes Paulson, 1875 , a species where the carapace (but not the chelipeds and ambulatory legs) is also uniformly brown to tan in preserved specimens, the chelipeds cannot be described as glossy since they are covered by small but distinct tubercles. Serène (1984) synonymised T. rubridactyla Garth, 1971 with T. laevissima without comment, an action we do not agree with. Tetralia rubridactyla typically has a prominent crest along the anterior margins of the cheliped merus, and the distal edge of the cheliped merus as well as the dorsal surface of the cheliped merus and propodus are dark brown in colour when alive, characters that are clearly absent in Stimpson's figure or description. The posterior portion of the carapace of T. laevissima appears very narrow, as in members of Tetraloides , but we believe this is due merely to the figure being schematic. A setae­filled depression on the dorsal proximal surface of the cheliped propodus, diagnostic for Tetralia is absent in Tetraloides , but is clearly indicated in Stimpson's drawings ( Stimpson 1907: pl. 9, figs. 4, 4a).

As already discussed by Castro (1997a: 67), the name Tetralia glaberrima forma fulva Patton, 1966 , is invalid under the current zoological code. Its first valid use was apparently by Serène (1984), who also used Patton's name as a subspecies, T. glaberrima fulva . As Patton's material was no longer extant, Castro (1997a: 65) designated a neotype of T. fulva Serène, 1984 , from Queensland, Australia. It is also worthwhile to note that the first nomenclaturally valid use of " fulva " may in fact be by Ribes (1978: 14) who used the name " Tetralia glaberrima fulva " in her doctoral thesis. This thesis, however, had a very limited circulation and is not well known outside France, and is not here regarded as a valid publication. Even if Ribes' thesis is considered a valid publication (as might be shown later), it will not affect the taxonomy of the species because on the basis of the present study Tetralia glaberrima fulva is an objective junior synonym of Cancer glaberrimus Herbst, 1790 (see below).

Castro (1997a: 68) had shown that T. sanguineomaculata Galil & Clark, 1990 (type locality New Caledonia), is a junior subjective synonym of T. fulva .

The recognition of the poorly understood C. glaberrimus Herbst, 1790 , as a senior synonym of Tetralia fulva Serène, 1984 , Trapezia integra Latreille, 1828 , Trapezia serratifrons Jacquinot, 1846 , and Tetralia laevissima Stimpson, 1858 , does not cause any problems. The name and taxonomic concept of Tetralia fulva was only established with certainty relatively recently ( Galil 1988a) and the name has been seldom used. In any case, as discussed earlier, Tetralia fulva Serène, 1984 , has to be replaced by Trapezia integra Latreille, 1828 , anyway. We believe that our present action best serves the interest of longterm nomenclatural stability.

To this effect and to maintain stability, we hereby designate the neotype of Tetralia fulva Serène, 1984 , designated by Castro (1997a: 65), a male (MNHN­B 25234; cl 7.3 mm, cw 8.4 mm) from Heron Island (23º26’N, 151º55’E), Queensland, Australia, as the simultaneous neotype of Cancer glaberrimus Herbst, 1790 . We also designate this specimen as the neotype for Trapezia integra Latreille, 1828 , Trapezia serratifrons Jacquinot, 1846 , and Tetralia laevissima Stimpson, 1858 . This action effectively makes all five names objective synonyms of C. glaberrimus Herbst, 1790 .