Carcinoplax inaequalis ( Yokoya, 1933 )

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 : 633-634

Carcinoplax inaequalis ( Yokoya, 1933)

Pilumnoplax inaequalis Yokoya, 1933: 194 , 217, 220, fig. 63 [ Japan]. — Sakai 1935: 183, pl. 54, fig. 1 [ Japan]. — Imaizumi 1960: 219 [ Japan]. — Chen 1984: 193.

Homoioplax haswelli – Sakai 1939: 566, pl. 102, fig. 2; 1940: 42 [in list]; 1976: 540, fig. 287 [ Japan]. — Miyake et al. 1962: 130 [in list] [ Japan]. — Kikuchi & Miyake 1978: 42 [in list] [ Japan]. — Miyake 1991: 220 [in list] [ Japan] (not Homoioplax haswelli Miers, 1884 ).

Homoioplax inaequalis – Serène 1968: 90 [in list].

? Not Pilumnoplax inaequalis – Guinot 1969b: 526, figs 62, 79, 80 (= C. longimana (de Haan, 1833)) .

Carcinoplax inaequalis – Sakai 1969: 269 [in list]. — Guinot 1971: 1081 [in list]. — Serène & Lohavanijaya 1973: 62 [in list], 64 [in key].

Not Carcinoplax inaequalis – Ho et al. 2004: 660, fig. 6G [ Taiwan] (= Carcinoplax cracens n. sp.).

TYPE MATERIAL. — ♂ dry lectotype, cl 11.6 mm, cw 15.6 mm ( KMNH IvR 100,002) ; 2 ♀♀ dry paralectotypes (cl 6.6 mm, cw 9.0 mm; cl 6.0 mm, cw 10.0 mm) ( KMNH IvR 100,006) ; 2 ♀♀ dry paralectotypes (cl 7.7 mm, cw 11.0 mm; cl 8.0 mm, cw 11.6 mm) ( KMNH IvR 100,004) .

TYPE LOCALITY. — Japan, Shikoku, northeast of Asizurizaki [Cape Ashizuri], 130 m.

MATERIAL EXAMINED. — Japan. Honshu, south of Inuboe-zaki [Cape Inuboe], stn 9, 238 m, 22.VI.1926,

2 ♀♀ paralectotypes ( KMNH IvR 100,006). — Off Maisaka, Shizuoka-ken, stn 194, 192 m, 1.VII.1927, 2 ♀♀ paralectotypes ( KMNH IvR 100,004).

Shikoku, northeast of Asizuri-zaki [Cape Ashizuri], stn 337, 130 m, 26.VII.1928, ♂ lectotype ( KMNH IvR 100,002).

DISTRIBUTION. — Japan (see Sakai 1976). Depth: 35- 384 m.

REMARKS

The species was not mentioned by Guinot (1989) in her revision of Carcinoplax but was commented upon in an earlier publication ( Guinot 1969b: 526). The taxonomy of the species was discussed by Ho et al. (2004: 660) but their Taiwan material did not belong to C. inaequalis but to a species being described as new, C. cracens n. sp. (see above).

The validity of C. inaequalis and its inclusion in Carcinoplax has been confirmed by the examination of five of the 20 syntype specimens listed in its description ( Yokoya 1933: 194). The only male among the specimens examined is designated herein as the lectotype (KMNH IvR 100,002), and the four females as paralectotypes (KMNH IvR 100,004, 100,006). All characters agree with the description including the “two well-marked transversal carinae; the anterior on the gastric and another on the cardiac region”, which unfortunately are not indicated in the drawing accompanying the description ( Yokoya 1933: 195, fig. 63). The anterolateral teeth are slender, with an acute tip, a character not clearly shown in Yokoya’s drawing. The ambulatory legs (P2-P5) are relatively short and thick, another character that distinguished C. inaequalis from C. cracens n. sp. (see Remarks for C. cracens n. sp. above).

Carcinoplax inaequalis was placed in synonymy with Carcinoplax surugensis Rathbun, 1932 by Takeda & Miyake (1969a). The material examined by them belonged indeed to C. surugensis as evidenced by their illustrations ( Takeda & Miyake 1969a: fig. 2) of the characteristic G1, G2, and male abdomen of this species (see Remarks for P. surugensis n. comb. and its inclusion in Pycnoplax n. gen. below). This is very puzzling since the authors ( Takeda & Miyake 1969a: 459) state that they examined dried specimens identified by Yokoya as Pilumnoplax inaequalis , including “some syntypes ”. The syntype selected as the lectotype (see above) was actually examined by Takeda as confirmed by the label “ Carcinoplax surugensis Rathbun, 1932 (June 1969, M. Takeda det.)” that was found together with the specimen. It seems that Takeda did not examine the G1 and G2 of the lectotype since the abdomen of the dried specimen was tightly closed. To add to the confusion, Sakai (1976: 540) erroneously referred to the P. surugensis n. comb. record of Takeda & Miyake (1969a) as C. inaequalis (as Homoioplax haswelli ), obviously unaware of the sharp differences in their respective G1 and G2.

The G1 of the lectotype of C. inaequalis is typical of Carcinoplax (i.e. long, slender, and thin, being dorso-ventrally flattened). It has a pointed tip. The G2 (with flagellum that is shorter than the proximal portion) and narrow male abdomen are also characteristic of Carcinoplax . In Pycnoplax n. gen. the G1 is stout, thick, proximally broad, the G2 has a flagellum that is as short (as in P. surugensis n. comb.) or slightly shorter than the proximal portion, and the male abdomen is wider than in Carcinoplax (see Remarks for Pycnoplax n. gen. below).

The material from Taiwan identified as C. inaequalis by Ho et al. (2004: 660) is characterized by long and slender ambulatory legs (P2-P5) and is being described as a new species ( C. cracens n. sp.). Other differences and similarities between C. inaequalis and C. cracens n. sp. are given in the Remarks section of C. cracens n. sp. (above).