Neommatocarcinus Takeda & Miyake, 1969

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 : 751-753

Genus Neommatocarcinus Takeda & Miyake, 1969

Neommatocarcinus Takeda & Miyake, 1969b: 173 . — Guinot 1971: 1082 [list of species]. — Karasawa & Kato 2003b: 140 [in list].

TYPE SPECIES. — Ommatocarcinus huttoni Filhol, 1885 (by monotypy, gender masculine).

SPECIES INCLUDED . — Neommatocarcinus huttoni (Filhol, 1885) .

The genus is far known only from temperate waters in New Zealand.

DIAGNOSIS. — Carapace ( Fig. 51 ; Takeda & Miyake 1969b: pl. 2, fig. A; McLay 1988: fig. 58a) transversely rectangular, much wider than long, widest at conspicuous outer orbital teeth; front narrow, deflected ventrally, slight median projection ( Takeda & Miyake 1969b: fig. 5a). Dorsal surface of carapace granular, convex, without clear indication of regions. Anterolateral teeth absent. Wide notch between frontal margin, inner edge of supraorbital border. Orbits wide, greatly expanded distally, fissure absent. Eye peduncle ( Fig. 51 ; Takeda & Miyake 1969b: pl. 2, fig. A; McLay 1988: fig. 58) long, much longer than front (1.4-1.6 front width), eyes beyond outer orbital tooth; cornea elongated, spherical distal margin, not reniform. Supraorbital borders convex, slight subproximal lobe; suborbital borders sinuous, with large, keel-like inner tooth; lateral borders convex; anterolateral tooth absent. Basal antennal article short, subcylindrical, distalmost (third) article reaches front, lying freely in orbital hiatus, not reaching front. Antennules not separated by septum. Buccal cavern narrow anteriorly, strongly crested. 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. Anterior end of sterno-abdominal cavity anterior to thoracic sternite 4. Prolongation of male episternite 7 present; thoracic sternite 7 laterally covered with thoracic sternite 8; thoracic sternite 8 without supplementary plate. Chelipeds ( Fig. 51 ; Takeda & Miyake 1969b: fig. 5b; McLay 1988: fig. 58) larger in males; fingers long, slender, slightly curved, light in colour, shorter than elongated propodus; carpus with broad tooth on inner (ventral) margin, acute tooth on outer (dorsal) margin; merus with 3 or 4 long, acute teeth on distal, outer (dorsal) margin (short, obtuse in large specimens); short, acute tooth on each median portion of inner (ventral), outer (dorsal) margins. Ambulatory legs (P2-P5) ( Fig. 51 ) compressed, dorsal margins of meri with acute distal tooth (obsolete in large individuals), row of tubercles increasing in size distally, sometimes acute; dactyli slender, dorso-ventrally flattened, with slight carina on each side, setose. Male abdomen ( Takeda & Miyake 1969b: fig. 6a) narrowly triangular, narrower than sternum, somites 3-5 being narrower than thoracic sternite 7; with 4 freely-movable somites (somites 3-5 fused) plus telson, shallow carina along widest, proximal portion of fused somites 3-5. Telson slightly wider than long, rounded anterior margin. Posterior border of somites 3-5 (carinated portion) covers space between P5 coxae, somite 2 much narrower than somites 3-5 so that somites 1, 2 leave large portion of thoracic sternite 8 visible ( Takeda & Miyake 1969b: fig. 6a). Locking mechanism with medium-size vulvar cover on edge of thoracic sternite 5, shallow socket on underside (ventral surface) of abdominal somite 6. Male opening coxal. Penis arising from P5 coxa, sclerified portion between thoracic somites 7, 8 before soft portion ( Takeda & Miyake 1969b: fig. 6b). G1 ( Takeda & Miyake 1969b: fig. 5d) long, slender, thin, nearly straight, only slightly broadened proximally; pointed, thin tip. G2 slender, longer than G1, flagellum shorter than proximal part (peduncle); curved, pointed tip. Female abdomen with 6 freely-movable somites, wide.Telson much wider than long. Somite 2 covers most space between P5 coxae, somite 2 narrower than somite 3 but somites 1, 2 leave relatively large portion of thoracic sternite 8 visible. Vulva of mature females ovoid, on large, sclerified prominence extending from deflected 5/6 suture to close to 6/7 suture, covered by soft membrane, vulvar cover absent.

REMARKS

Takeda & Miyake (1969b) separated Ommatocarcinus huttoni (Filhol, 1885) from the other known species of Ommatocarcinus by creating a new genus, Neommatocarcinus , on account of several unique characters. The male abdomen has only four somites plus telson, somites 3-5 being fused. This is unique among members of the family Goneplacidae , although somites 3-5 are distinct but immovable in the family Mathildellidae of the superfamily Goneplacoidea . Another unique character for a goneplacid is the absence of the antennular septum. The vulva is also distinct, being surrounded by a sclerified, elevated prominence, a structure that has never been described in other goneplacids. In contrast to other goneplacines, the penis has a sclerified proximal portion that is externally visible (see Takeda & Miyake 1969b: fig. 6 a, b). Although the male genital opening of the Euryplacidae has been described as sternal (Davie 2002), it is coxo-sternal, with the penis located in a groove or “canal” formed by the concave thoracic sternite 8. The flagellum of the G2 is long and with a distinctively curved, nearly coiled, tip, a character that is also observed in a goneplacine, Goneplacoides marivenae ( Komatsu & Takeda 2003: fig. 3e, as Goneplax marivenae , fig. 6e, as Goneplax megalops ).

All other morphological characters studied (thoracic sternum, female abdomen, relationship between abdomen and sternum in both sexes, and G1) are suggestive of strong goneplacine affinities. Neommatocarcinus is thus kept in the subfamily Goneplacinae rather than placing it in a new subfamily.

Neommatocarcinus huttoni (Filhol, 1885) ( Fig. 51 )

Ommatocarcinus huttoni Filhol, 1885a: 13 , 50 [in list]; 1885b: 384, pl. 43, figs 1, 2, 5 [ New Zealand]. — Dell 1951: 25 [in list] [ New Zealand]. — Probert & Batham 1979: 381, 387 [in list] [ New Zealand]. — Wear & Fielder 1985: 10 [in list], 62, 79 [in list], 84 [in key], figs 165-168 [larvae] [ New Zealand]. — Guinot 1979: 219.

Ommatocarcinus macgillivrayi – Miers 1886: xxiii, xxxvii, xlviii, 247 [ New Zealand]. — Chilton 1911: 287 [in list], 292 [ New Zealand]. — Thompson 1912: 237 [in list] [ New Zealand]. — Thompson & Anderton 1921: 99, unnumb. figs [larvae] [ New Zealand]. — Chilton & Bennett 1929: 757 [ New Zealand]. — Richardson 1949: 36 [in key], fig. 21 [ New Zealand]. — Dell 1960: 5; 1963a: 48, unnumb. fig.; 1968a: 26 [in list]; 1968b: 232, 233, 238 [ New Zealand]. — Bennett 1964: 74, 88, figs 79-83 [ New Zealand].

Neommatocarcinus huttoni – Takeda & Miyake 1969b: 174, 175, figs 5, 6, pl. 2, fig. A [ New Zealand]. — Guinot 1971: 1082 [in list]. — Fenwick 1978: 208 [in list] [ New Zealand]. — McLay 1988: 262, fig. 68 [references] [ New Zealand].

TYPE MATERIAL. — Dry ♀ holotype, cl 15.4 mm, cw 34.0 mm ( MNHN-B 4608).

TYPE LOCALITY. — New Zealand, South Island, Otago Harbour.

MATERIAL EXAMINED. — New Zealand. Tangaroa , stn 5364, 3 ♂♂, 2 ♀♀ ( NIWA).

Revision of Goneplacinae ( Crustacea, Brachyura)

Otago Harbour, 1 dry ♀ holotype, cl 15.4 mm, cw 34.0 mm ( MNHN-B 4608).

Queen Charlotte Sound, near Long I., Challenger, stn 167A, 18 m, 1 ♂, cl 6.7 mm, cw 15.5 mm, 2 ovig. ♀♀ (cl 8.9 mm, cw 18.8 mm; cl 10.5 mm, cw 23.1 mm) ( BMNH 84.31 ) .

DISTRIBUTION. — Known only from New Zealand. Depth: 18-260 m ; also in a sample taken from 42-594 m.

COLOUR

Takeda & Miyake (1969b: 178) and McLay (1988: 262) described the dorsal surface of the carapace as “yellowish vermillion” with white and purple portions; parts of the ventral surface brick red, and chelipeds and ambulatory legs mostly “whitish or creamy white” with brick red, purplish red, yellow, purple, and pale orange portions.

REMARKS

Neommatocarcinus huttoni had previously been confused with Ommatocarcinus macgillivrayi White, 1852 . Chilton (1911: 292) considered them to be conspecific, and confusion persisted among most carcinologists until Takeda & Miyake (1969b) pointed out the fusion of somites 3-5 in the male abdomen and other unique characters of O. huttoni and placed in a new genus, Neommatocaricinus.

In addition to the male abdomen, N. huttoni can be distinguished from O. macgillivrayi by the absence of an antennular septum, the presence of 3 or 4 acute teeth (which become obtuse in large individuals; see Takeda & Miyake 1969b: pl. 2, fig. A) on the proximal margin of the cheliped merus (one median, obtuse tooth in O. macgillivrayi ), the absence of an obvious stridulating mechanism, a G1 with a slender tip (broader and dorso-ventrally flattened in O. macgillivrayi ), a G2 with a curved flagellum (straight in O. macgillivrayi ), and the absence of a ridge across the width of the carapace ( Fig. 51 ) (present in O. macgillivrayi ). In contrast to O. macgillivrayi , which was described by Takeda & Miyake (1969b: 178) as “uniformly pinkish with darker spots”, the colour pattern of N. huttoni is rather striking (see Colour above).

Neommatocarcinus huttoni , which is known by the common name of “policeman crab”, lives in sandy bottoms in temperate waters in New Zealand. It makes temporary furrows in the sand, leaving the long eye peduncles protruding from the sediment ( McLay 1988: 264).

Figures

FIG. 51. — Neommatocarcinus huttoni (Filhol, 1885),♀, dry holotype,cl 15.4 mm,cw 34.0 mm,Otago Harbour,New Zealand (MNHN-B 4608).