Ommatocarcinus White, 1852

Castro, Peter, 2007, A reappraisal of the family Goneplacidae MacLeay, 1838 (Crustacea, Decapoda, Brachyura) and revision of the subfamily Goneplacinae, with the description of 10 new genera and 18 new species, Zoosystema 29 (4), pp. 609-774 : 734-735

Genus Ommatocarcinus White, 1852

Ommatocarcinus White, 1852: 393 . — H. Milne Edwards 1852: 163. — Miers 1886: xiv, 237 [in list], 246. — Ortmann 1898: 1176 [in list]. — Alcock 1900: 293 [in list]. — Chilton & Bennett 1929: 757 (part). — Sakai 1939: 563 [in key], 564; 1940: 47, 48 [in list]. — Barnard 1950: 282 [in key], 285. — Balss 1957: 1656 (part). — Guinot-Dumortier & Dumortier 1960: 142, 144 [stridulating mechanism]. — Bennett 1964: 74 [discussion] (part). — Serène 1968: 89 [in list]. — Glaessner 1969: R525 [diagnosis]. — Guinot 1969b: 520, 523 [discussion]; 1971: 1081 [list of species] (part). — Takeda & Miyake 1969b: 174 [discussion] (part). — Dai et al. 1986: 377 [key to species]. — Yamaguchi et al. 1987: 23. — Chen 1998: 285 (part). — Davie 2002: 200 [diagnosis]. — Dai & Yang 1991: 407 [key to species]. — Karasawa & Kato 2003b: 130 [in list], 140 [in list], 141 [in table] (part). — Poore 2004: 438. — Karasawa & Schweitzer 2006: 40 (part).

Not Ommatocarcinus – Filhol 1885b: 384 (= Neommatocarcinus Takeda & Miyake 1969 ).

Not Ommatocarcinus – Tesch 1918: 186 (= Singhaplax Serène & Soh, 1976 ).

TYPE SPECIES. — Ommatocarcinus macgillivrayi White, 1852 (by monotypy, gender masculine). Name placed in Official List of Names in Zoology (with the officially designated type species) in Opinion 85, Direction 37 (see Melville & Smith 1987: 135).

EXTANT SPECIES INCLUDED . — Ommatocarcinus fibriophthalmus Yokoya, 1933 ; O. granulatus Chen, 1998 ; O. macgillivrayi White, 1852 ; O. pulcher Barnard, 1950

All species are restricted to the Indo-West Pacific region (one species has been recorded from temperate waters in New Zealand but this is most probably the result of misidentifications).

FOSSIL SPECIES INCLUDED ( Karasawa & Kato [2003b]). — Ommatocarcinus corioensis (Creswell, 1886) , Ommatocarcinus sp.cf. O. macgillivrayi White, 1852 , O. taiwanicus Hu &Tao, 1996 , Ommatocarcinus sp. of Feldmann & Keyes (1992).

SPECIES NOT INCLUDED IN OMMATOCARCINUS . — Ommatocarcinus elegans Chen, 1998 (in Microgoneplax n. gen.)

Ommatocarcinus orientalis Tesch, 1918 (in Singhaplax Serène & Soh, 1976 )

DIAGNOSIS. — Carapace ( Barnard 1950: fig. 53b; Poore 2004: fig. 141a) transversely rectangular, much wider than long; widest at conspicuous outer orbital teeth; front ( Barnard 1950: 53 d) deflected ventrally, slight median projection. Wide notch between front, inner edge of supraorbital border; orbits wide, greatly expanded distally; supraorbital borders sinuous, concave; suborbital borders slightly sinuous, with wide, obtuse inner tooth not visible dorsally; anterolateral borders convex. Dorsal surface of carapace smooth or conspicuously granular, with slight horizontal ridges, moderately convex, without clear indication of regions. Outer orbital angle with conspicuous, acute tooth; anterolateral tooth absent (obtuse prominence in O. fibriophthalmus Yokoya, 1933 ). Basal antennal article short, distalmost (third) article reaches front. Eye peduncles long, much longer than front (at least 3 times front width); cornea elongated, not reniform (not conspicuously dorso-ventrally flattened, not clearly divided into anterior and posterior portions). Stridulating mechanism of rubbing proximal portion of cheliped (P1) merus against pterygostomial ridge. Thoracic sternum wide. Median sulcus on thoracic sternite 4 absent; sutures 4/5, 5/6, 7/8 interrupted medially, 6/7 complete. Anterior end of sterno-abdominal cavity anterior to thoracic sternite 4. Cheliped fingers long, slender, slightly curved, shorter than elongated propodus; varying portion of fingers may be darker in colour, tip light; carpus with broad tooth on inner margin (merus with median tooth in O. macgillivrayi ). Dorsal margins of ambulatory leg (P2-P5) meri smooth or with acute distal tooth; dactyli slender, dorso-ventrally flattened, with carina on each side, setose. Male abdomen with 6 freely-movable somites plus telson, relatively wide, somites 4-6 gradually decreasing in width from somite 3 (widest somite). Telson slightly longer than wide. Somite 3 covers space between P5 coxae, somite 2 much narrower than somite 3 so that somites 1, 2 leave small to large portion of thoracic sternite 8 visible. G1 ( Barnard 1950: fig. 53f; Dai & Yang 1991: fig. 199-1, 199-2) long, slender, thin, slightly sinuous, only slightly broadened proximally; pointed, thin tip. G2 slender, slightly longer than G1, flagellum shorter than proximal part (peduncle); curved, slightly-expanded tip with 2 spinules. Penis arising from P5 coxa, moderate size; broad, soft proximal expansion.Female abdomen with 6 freely-movable somites, wide.Telson much wider than long. Somite 3 covers space between P5 coxae, somite 2 slightly narrower than somite 3 but somites 1, 2 leave relatively large portion of thoracic sternite 8 visible. Vulva of mature females ovoid, enlarged, extending from deflected 5/6 suture to close to 6/7 suture, covered by soft membrane, vulvar cover absent.

REMARKS

The four species of Ommatocarcinus are characterised by greatly elongated eye peduncles and orbits, which together with a wide, transversely rectangular carapace, and conspicuous, acute outer orbital teeth show striking convergence with species of Microgoneplax n. gen., Neommatocarcinus , Singhaplax , and in some ways with Goneplax sensu stricto. Species of these genera inhabit soft subtidal bottoms at moderate depths.