Genetic and morphometric comparisons of squat lobster, Munidopsis scobina (Decapoda : Anomura : Galatheidae) populations, with notes on the phylogenyof the genus Munidopsis

Specimens of the galatheid Municdopsis scobina were collected from two stat ions on the continental slope off Oman, at depths of 900 and 1000 m, using an Agassiz trawl, Starch gel electrophoresis, across 10 enzyme loci, was ca rried out on 427 specimens. Genetic variability was calculated for both pop ulations using a number of parameters. F-statistics were used to estimate g enetic variance within (F-IS) and between (F-ST) populations. Significant d eviations from Hardy-Weinberg expectations were detected at one locus (Gotb ), Analyses of F-IS revealed significant differences from zero at Gotb and Pgm, as a result of heterozygote deficiency. No relationship was observed b etween size of individuals and genotype. The number of genetically effectiv e migrants per deme per generation (N(e)m) was calculated using both F-ST a nd private alleles methods. N(e)m values were theoretically sufficient to o ffset the effects of genetic drift. Additional morphometric analyses were c arried out on Munidopsis scobina from the two populations. Individuals were sexed (n = 2476 individuals) and ten parameters measured (n = 1238). All s pecimens were examined for parasites (either bopyrid isopod or rhizocephala n). Significant male-biased sex ratios were observed in both populations (p < 0.01). In addition, significant differences in size-frequency distributi ons (p < 0.01) were recorded both within sires between sexes, and within se xes between sites; possibly related to a size-dependent response to hypoxia . Significant differences also were observed in mean cheliped length betwee n sexes p < ( 0.01), potentially indicating that male nl. scobina exhibit a gonistic behaviour. The genetic relationships of Munidopsis scobina to four other species of Munidopsis (M crassa, M parfaiti, M. spinihirsuta and M. subsquamosa) and the confamilial Galathea squamifera were also examined usi ng allozyme loci. Within the genus Munidopsis, pairwise comparisons of gene tic identity were within the normal range expected for congeneric species. Comparisons between G. squamifera a and Munidopsis spp. were within the ran ge expected for confamilial genera. (C) 1999 Elsevier Science Ltd. All righ ts reserved.