Garthambrus allisoni (Garth, 1993)

Mclay, Colin L., 2009, Revision of the crab genus Garthambrus Ng, 1996, with the description of two new genera and discussion of the status of Tutankhamen Rathbun, 1925 (Crustacea: Brachyura: Parthenopidae), Zootaxa 2122, pp. 1-50 : 11-12

Garthambrus allisoni (Garth, 1993)

( Figs 5 C, D, 9 B)

Parthenope (Platylambrus) allisoni Garth, 1993: 790 , fig. 5 (in part). Garthambrus allisoni — Ng, 1996: 157.

Type material. HOLOTYPE: male 23.5 x 17.8 mm ( LACM; ex. AHF 645), Easter I. Fracture Zone, 25 º03’S 97 º 29 ’W, Carrousel Expedition, Dredge 5, stn 19, 591 m, Scripps Institution of Oceanography 64 –527, 1 Aug 1964 (after Garth 1993). Originally deposited at the Alan Hancock Foundation collection, the holotype male was apparently transferred to the Natural History Museum of Los Angeles County along with Garth’s crab collection. It was given a LACM catalogue number but this specimen has been misplaced (G. Davis, pers. comm.).

Material examined. Taiwan. MUSORSTOM EXPEDITION TAIWAN 1, stn DW56, 24º 29.8 ’N 122 º 12.6 ’E to 24 º 28.1 ’N, 122 º 12.6 ’E, 438–539 m, 4 Aug 2000: 1 female 14.1 x 10.9 mm ( NTOU); Same data as above: 1 ovig. female 12.5 x 9.9 mm ( ZRC 2001.2224).

French Polynesia. Bora Bora, SMCB, stn D32, 16º 28.37 ’S, 151 º 47.52 ’E, 562 m, 23 Jun 1901: 1 female 14.1 x 11.0 mm ( MNHN, MP B- 22421).

Diagnosis. Carapace dorsally tuberculate, not spinose, without deep lacunae; supra-orbital region not spinose. Tubercles on protogastric, mesogastric, epibranchial, mesobranchial and cardiac regions fusing to form smooth ridges or plates. Frontal projection short, less than one quarter length of carapace. Epibranchial marginal teeth tips sharp. Mesobranchial margin with raised angular patch; patch not smooth. Sub-orbital spine produced, spine tip extending beyond anterior outer corner of antennal article 2. Sub-branchial region densely tuberculate. Cheliped merus and carpus outer margins tuberculate, tubercles irregular, granular, tips sharp. P 5 merus, carpus and propodus upper margins tuberculate; posterior surface of merus, carpus and propodus tuberculate, tubercles paxilliform, stellate, edges fusing with adjacent tubercles.

Distribution. Garthambrus allisoni is known from the type locality near the island of Bora Bora, French Polynesia, and is now recorded for the first time from Taiwan.

Remarks. The specimen from Bora Bora ( MNHN, MP B- 22421) was originally listed by Garth (1993: 782) as Parthenope (Platylambrus) poupini . Re-examination of this specimen indicated that it should be referred to G. allisoni instead. The tips of the epibranchial teeth are serrated and not blunt, like those in G. poupini . In addition, the tubercles on the protogastric, mesogastric, epibranchial, mesobranchial and cardiac regions fuse to form ridges, characters that are absent in G. poupini .

This species is one of two Garthambrus species that have stellate tubercles, the other being G. stellatus . It can be easily distinguished from G. stellatus , however, by having differently shaped epibranchial marginal teeth. In G. allisoni , the epibranchial teeth are arranged close together, whereas in G. stellatus , the epibranchial teeth are more widely spaced. In addition, G. allisoni has a fused patch of tubercles and ridges of tubercles on the dorsal surface of the carapace, which are absent in G. stellatus .