Garthinia, Forges, Bertrand Richer De & Ng, Peter K. L., 2009

Forges, Bertrand Richer De & Ng, Peter K. L., 2009, New genera, new species and new records of Indo-West Pacific spider crabs (Crustacea: Brachyura: Epialtidae: Majoidea), Zootaxa 2025, pp. 1-20 : 6-7

Garthinia n. gen.

Diagnosis. Carapace triangular. Very long bifid rostrum formed by 2 parallel cylindrical spines, adjoined along entire length. Antennae shorter than half length of rostral spines. Supraocular eave narrow, rounded on extremities. Carapace, legs covered by tomentum of cone-shaped setae giving spiny appearance. Carapace border divided in 2 lobes, 1 hepatic, 1 branchial. Branchial region enlarged, forming blunt point laterally. Surface of carapace relatively flat, with several tubercles; several tubercles present on border of pterygostomian region. Cheliped longer than P2. Male anterior thoracic sternal sutures interrupted. Male abdomen with 7 free somites including telson.

Etymology. The genus is established to honor the late John S. Garth, Allan Hancock Foundation, University of Southern California, U.S.A., who spent a large part of his life working on the spider crabs of America, and whose contributions have been instrumental in the taxonomy of majoids. The gender of the genus is feminine. The type species is Garthinia disica n. sp. by monotypy.

Remarks. The new genus is related to the Pisinae. The closest genera appear to be Sphenocarcinus Milne- Edwards, 1875, Rochinia A. Milne-Edwards, 1875 , and Oxypleurodon Miers, 1886 . The shape of the carapace and the absence of plates easily separate it from Sphenocarcinus and Oxypleurodon . The G1 is also quite different from these genera, being curved and flattened in the third distal part. In the other two genera, the G1 is almost straight and sharp.

In Rochinia the carapace is pyriform (triangular in Garthinia ); the hepatic and branchial spines are always prominent and very conspicuous (no spines at all in these area in Garthinia ); the supraocular eave terminates as a forwardly directed tooth (no tooth in Garthinia ); and the first pair of ambulatory legs are clearly the longest (P2 shorter than cheliped in Garthinia ).

The general shape of the carapace of Garthinia is superficially similar to that of Sphenocarcinus , notably in the triangular carapace with two long rostral spines. However, the two genera are very different. In Garthinia , the two rostral long spines are parallel along their entire length (parallel only on the proximal half and diverging after that in Sphenocarcinus ); the border of the carapace is divided in two lobes (continuous in Sphenocarcinus ); and the cheliped is longer than the P2 (shorter than the P 2 in Sphenocarcinus ).