Neogoneplax, Castro, 2007

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 : 699-700

Genus Neogoneplax n. gen.

Goneplax – Tesch 1918: 181 (part). — Sakai 1939: 562 [in key], 563; 1976: 537 (part). — Balss 1957: 1656 (part). — Guinot 1969b: 520; 1971: 1081 (part). — Serène 1964: 189, 190; 1968: 89 (part). — Dai et al. 1986: 376 (part). — Dai & Yang 1991: 406 (part). — Karasawa & Kato 2003b: 130 [in list], 140 [in list], 141 [in table] (part). — Komatsu & Takeda 2003: 1243 (part).

TYPE SPECIES. — Goneplax renoculis Rathbun, 1914 (by present designation; gender feminine).

SPECIES INCLUDED . — Neogoneplax costata n. sp.; N. renoculis ( Rathbun, 1914) n. comb.; N. serratipes n. sp.

All species are restricted to the Indo-West Pacific region.

ETYMOLOGY. — From neos, Greek for “new”, and the generic name Goneplax , to indicate that although the species included in the new genus superficially resemble Goneplax in the general shape of their carapaces and the elongated eye peduncles, they actually belong to a separate new genus.

DESCRIPTION

Carapace ( Figs 28B ; 30A ; 31 ; 33A ; 34 ; Chen 1998: fig. 11-1) transversely rectangular, much wider than long; widest at conspicuous outer orbital teeth; front slightly deflected ventrally, sinuous, marked by 2 slight emarginations, small to minute median projection between emarginations. Slight notch between front, inner edge of supraorbital border; orbits wide, greatly expanded distally; supraorbital borders conspicuously convex; suborbital borders convex, with 1 or 2 slight, obtuse inner teeth not visible dorsally; anterolateral borders short, straight. Dorsal surface of carapace smooth or with slight horizontal ridges, moderately convex, without clear indication of regions. Outer orbital angle with conspicuous, acute tooth; acute anterolateral tooth on each side of carapace (much reduced in N. costata n. sp.). Basal antennal article short, distalmost (third) article nearly reaches front. Eye peduncles ( Figs 28B ; 30A ; 31 ; 33A ; 34 ) long, shorter than or longer than front (0.8-1.1 front width); cornea strongly reniform, dorso-ventrally flattened, nearly divided into anterior and posterior portions. Anterior border of endostome well demarcated from buccal cavern, ridges faint but clearly defined. Third maxillipeds nearly completely close the buccal cavern. No obvious stridulating mechanism other than possible rubbing of 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 ( Fig. 32 ). Anterior end of sterno-abdominal cavity anterior to thoracic sternite 4. Cheliped fingers ( Figs 28B ; 31 ; 34 ) long, slender, shovel-like, curved, pollex higher than dactylus in large individuals, shorter than elongated propodus; dactylus light in colour, without dark portion; carpus with conspicuous tooth on inner margin. Dorsal margins of ambulatory leg (P2-P5) meri unarmed ( N. costata n. sp.; Fig. 31 ), with acute distal tooth ( N. renoculis n. comb.; Fig. 28B ), or several teeth ( N. serratipes n. sp.; Figs 33B , 34 ); dactyli slender, with carina on each side, non-setose. Male abdomen ( Figs 30B ; 33C ; Chen 1998: fig. 11-3, as G. renoculis ) with 6 freely-movable somites plus telson, wide, somites 4-6 gradually decreasing in width from somite 3 (widest somite).Telson wide, clearly longer than wide. Somite 3 covers space between P5 coxae, somite 2 narrower than somite 3; somites 1, 2 leave small to large portion of thoracic sternite 8 visible. G1 varies from long, slender, slightly sinuous, slightly broadened proximally ( Fig. 30C ) to stout, short, with obtuse tip ( Fig. 33D ; Chen 1998: fig. 11-4, as G. renoculis ). G2 ( Figs 30D ; 33E ) slender, slightly shorter to slightly longer than G1, flagellum slightly longer than proximal part (peduncle), tip curved or straight, pointed. Penis arising from P5 coxa, moderate size; broad, soft proximal expansion. Female abdomen ( Dai & Yang 1991: fig. 198-2, as G. renoculis ) 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; somites 1, 2 leave small portion of thoracic sternite 8 visible. Vulva of mature females ( Fig. 32 ) small, oval, extending from 5/6 suture to median portion of thoracic sternite 6, vulvar cover present.

REMARKS

The new genus is described for Goneplax renoculis Rathbun, 1914 , which is different from the four mostly Atlantic species of Goneplax sensu stricto. The polyphyletic nature of Goneplax sensu lato and the questions surrounding the position of the Indo-West Pacific species of the genus are discussed in the Remarks section for Goneplax (see above).

Characters that separate Neogoneplax n. gen. from Goneplax sensu stricto and the five Indo-West Pacific genera that were formerly included in Goneplax sensu lato are summarized in Table 4.

Figures

FIG. 28. — A, Goneplacoides marivenae (Komatsu & Takeda, 2003) n. comb., ♀, cl 7.6 mm, cw 11.6 mm, off southern coast of New Caledonia, SMIB 8, stn DW 177, 320-370 m (MNHN-B 29262); B, Neogoneplax renoculis (Rathbun, 1914) n. comb., ♂, cl 10.1 mm, cw 16.0 mm, South China Sea off Philippine Is, MUSORSTOM 3, stn CP 108, 188-195 m (MNHN-B 10334); C, Paragoneplax serenei (Zarenkov, 1972) n. comb., ♂, cl 8.6 mm, cw 14.9 mm, north of New Caledonia, BATHUS 1, stn CP 669 (MNHN-B 29327).

FIG. 30. — Neogoneplax costata n. sp.: A, B, ♂ holotype,cl 10.4 mm,19.1 mm,Balicasag I., off Panglao I., Philippine Is (ZRC 2004.0723); A, dorsal surface of the carapace; B, abdomen; C, D, ♂ paratype, cl 12.8 mm, cw 24.5 mm (ZRC 2004.0721); C, left G1, dorsal view; D, left G2, ventral view. Scale bars: A, 5 mm; B, 3 mm; C, D, 1 mm.

FIG. 31. — Neogoneplax costata n. sp., ♂ holotype, cl 10.4 mm, 19.1 mm, Balicasag I., off Panglao I., Philippine Is (ZRC 2004.0723).

FIG. 33. — Neogoneplax serratipes n. sp., ♂ holotype, cl 8.3 mm, cw 11.9 mm, off eastern coast of New Caledonia, HALIPRO 1, stn CP 851, 241-250 m (MNHN-B 29836): A, dorsal surface of the carapace; B, right P5; C, abdomen; D, left G1, dorsal view; E, left G2, ventral view. Scale bars: A, 5 mm; B, C, 3 mm; D, E, 1 mm.

FIG. 34. — Neogoneplax serratipes n. sp., ♂ holotype, cl 8.3 mm, cw 11.9 mm, off eastern coast of New Caledonia, HALIPRO 1, stn CP 851, 241-250 m (MNHN-B 29836).

FIG. 32. — Neogoneplax costata n. sp., 1 ovig.♀ paratype,cl 11.9 mm,cw 22.8 mm,Balicasag I., off Panglao I., Philippine Is,200-300 m (ZRC), thoracic sternum, vulva, and vulvar cover.