Meeting Abstract
P3.199 Tuesday, Jan. 6 Molecular phylogeny of the true crabs (Crustacea: Decapoda: Brachyura) with an estimation of divergence time for the major lineages CHU, K.H. *; TSANG , L.M.; LAI, J.C.Y.; AHYONG, S.; NG, P.K.L.; Chinese Univ. of Hong Kong, China; Chinese Univ. of Hong Kong, China; National Univ. of Singapore, Singapore; National Inst. of Water and Atmospheric Research, Wellington, New Zealand; National Univ. of Singapore, Singapore kahouchu@cuhk.edu.hk
True crabs of the infraorder Brachyura represent one of the most diverse groups of crustaceans with almost 7000 described species inhabiting habitats from marine, freshwater to terrestrial. The relationships among the brachyuran families are poorly understood due to the high morphological diversity of the group. Using sequence data from three nuclear protein-coding genes (glyceraldehyde-3-phosphate dehydrogenase, sodium-potassium ATPase alpha-subunit and enolase), we attempt to reconstruct a phylogeny of the Brachyura. Preliminary results based on more than 50 species from over 20 families reveal that the basal Podotremata is paraphyletic, with Raninidae more closely related to Eubrachyura than to the other Podotremata. This is concordant with a previous analysis based on 18S rDNA sequences (Ahyong et al. 2007, Mol. Phylogenet. Evol. 45:576). Within the Eubrachyura, the analysis supports the reciprocal monophyly of the two subsections, Heterotremata and Thoracotremata. The close affinity of some of the families is evident (e.g. Homolidae + Latreilliidae; Xanthidae + Trapeziidae + Goneplacidae; Matutidae + Calappidae + Euryplacidae). The results corroborate the new classification scheme proposed by Ng et al. (2008, Raffles Bull. Zool. 17:1) to a certain extent (including most superfamily groupings). However, most of the internodes supporting superfamilial relationships remain poorly resolved, suggesting that further analyses will need to be done using more genes and taxa. The divergence times for the major lineages of Brachyura were estimated based on a Bayesian relaxed molecular method. [This work was supported by a RGC CERG grant (4419/04M) of HKSAR.]
