Macrophthalmus convexus, Stimpson, 1858

Barnes, R. S. K., 2010, A Review Of The Sentinel And Allied Crabs (Crustacea: Brachyura: Macrophthalmidae), With Particular Reference To The Genus Macrophthalmus, Raffles Bulletin of Zoology 58 (1), pp. 31-49 : 40

The Macrophthalmus convexus group

This intertidal group comprises only M. consobrinus Nobili, 1906 , M. convexus Stimpson, 1858 and M. parvimanus Guérin, 1834 ( Fig. 2C ). Although broadly similar to the M. brevis group above, it was shown to be separate by allozyme and molecular sequence data (Horii, Kitaura, Wada & Nishida, 2001; Kitaura et al., 2006), and morphologically it differs from them in possessing a large, flat, forwardly curved external orbital angle and in lacking the spine on the palm of the male chela. Like the M. brevis group, however, the corneas do not project, the carapace is broad (breadth> 2 × length) and the front narrow (breadth <10% that of carapace). The status of the various isolated geographical populations of M. parvimanus is currently somewhat uncertain. It is possible that several populations of M. convexus have given rise to M. parvimanus -like forms in different areas. Poupin (e.g. 1997) has been followed here and the Gambier Islands form, M. consobrinus , included as a distinct species, pending revision of the group. The M. convexus group is closely allied with the M. telescopicus group on both allozyme and molecular sequence data, and the two appear only distantly related to the M. brevis group ( Horii et al., 2001; Kitaura et al., 2006).

Figures

Fig. 2. Form of the carapace and adult male chela of subgroups of the genus Macrophthalmus II, the subgenus Macrophthalmus part 1: (a) M. telescopicus group, (b) M. brevis group, and (c) M. convexus group. Scale bars = 5mm.