GONEPLACINAE MacLeay, 1838

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 : 618-620

Subfamily GONEPLACINAE MacLeay, 1838

Gonoplacidae MacLeay, 1838: 64. — Ortmann 1894: 684; 1896: 416, 446 (part).

Carcinoplacinae H. Milne Edwards, 1852: 164 . — Miers 1886: 223 (part). — Ortmann 1894: 685; 1898: 1176 (part). — Borradaile 1907: 485 [in key] (part). — Rathbun 1918: 16 [in key], 17, 265 [diagnosis] (part). — Monod 1956: 340 [in key]. — Balss 1957: 1655 [in key], 1655 (part). — Serène 1964: 188 (part); 1968: 89 [in list] (part). — Sakai 1965: 165 [in key], 166 (part); 1976: 522 [in key], 523 (part). — Glaessner 1969: R524 [diagnosis]. — Guinot 1969b: 519 (part); 1971: 1081 [list of genera and species] (part). — Serène & Lohavanijaya 1973: 62. — Takeda & Shimazaki 1974: 59 [discussion]. — Dai et al. 1986: 365 (part). — Dai & Yang 1991: 393 (part). — Tirmizi & Ghani 1996: 76 [diagnosis]. — Davie 2002: 192, 193 (part). — Hsueh & Huang 2002: 113 [in key] (part). — Karasawa & Kato 2003b: 130 [in list] (part). — Števčić 2005: 67 [diagnosis] (part). — Ng & Manuel-Santos 2007: 40 [discussion].

Gonoplacinae – Miers 1886: 237 (part). — Alcock 1900: 286, 293, 316 (part). — Borradaile 1907: 485 [in key] (part). — Calman 1909: 315 [in list] (part).

Carcinoplacidae – Ortmann 1894: 684, 685; 1896: 416, 446; 1898: 1175 [diagnosis] (part). — Stebbing 1905: 34 [discussion].

Goneplacidae – Ortmann 1898: 1176 [diagnosis] (part). — Karasawa & Schweitzer 2006: 26 [in list], 36 [discussion].

Pseudorhombilinae Alcock, 1900: 286, 292, 297 (part). — Tesch 1918: 153 (part). — Sakai 1939: 554 [in key], 555 [key to genera].

Goneplacinae – Rathbun 1918: 16 [in key], 24 [diagnosis] (part). — Tesch 1918: 181 (part). — Balss 1957: 1655 [in key], 1656 (part). — Sakai 1939: 554 [in key], 562 [key to genera]; 1965: 165 [in key], 169 (part); 1976: 522 [in key], 537 (part). — Stephensen 1946: 226 [male pleopods]. — Bennett 1964: 73 [discussion]. — Serène 1964: 189 (part). — Glaessner 1969: R526 [diagnosis] (part). — Guinot 1969b: 519 (part); 1971: 1081 [list of genera and species] (part). — Serène & Umali 1972: 77 [key to species]. — Ingle 1980: 109 [diagnosis]. — Wil- liams 1984: 431 [in key], 433. — Dai et al. 1986: 376 (part). — Dai & Yang 1991: 406 (part). — Davie 2002: 200 (part). — Hsueh & Huang 2002: 113 [in key] (part). — Karasawa & Kato 2003b: 130 [in list], 137 [in list], 140. — Števčić 2005: 68 [diagnosis] (part).

GENERA INCLUDED . — Carcinoplax H. Milne Edwards, 1852 ; Entricoplax n. gen.; Exopheticus n. gen.; Goneplacoides n. gen.; Goneplax Leach, 1814 ; Hadroplax n. gen.; Menoplax n. gen.; Microgoneplax n. gen.; Neogoneplax n. gen.; Neommatocarcinus Takeda & Miyake, 1969 ; Notonyx A. Milne-Edwards, 1873 ; Ommatocarcinus White, 1852 ; Paragoneplax n. gen.; Psopheticus Wood-Mason, 1892 ; Pycnoplax n. gen.; Singhaplax Serène & Soh, 1976 ; Thyraplax n. gen.

FOSSIL GENERA INCLUDED . — Amydrocarcinus Schweitzer, Feldmann, Gonzáles-Barba & Vega, 2002 (in Amydocarcinidae Števčić, 2005; in Goneplacidae in Karasawa & Schweitzer [2006] ).

Icriocarcinus Bishop, 1998 (in Goneplacinae in Karasawa & Kato [2003a] and Karasawa & Schweitzer [2006]; subfamily Icriocarcininae in Števčić [2005] ).

Magyarcarcinus Schweitzer & Karasawa, 2004 (in Goneplacidae in Karasawa & Schweitzer [2006] ).

GENERA NOT INCLUDED IN GONEPLACINAE SENSU STRICTO (see Remarks). — Bathyplax A. Milne-Edwards, 1880 . Conleyus Ng & Ng, 2003 (in family Conleyidae Števčić, 2005 in Števčić [2005] and Ng & Manuel-Santos [2007]).

Paragalene Kossmann, 1878 (in family Geryonidae Colosi, 1923 in Števčić [2005] ; unknown status in Karasawa & Schweitzer [2006]).

Progeryon Bouvier, 1922 (incertae sedis in family Goneplacidae in Karasawa & Kato [2003a] ; in family Geryonidae Colosi, 1923 in Števčić [2005] ; Progeryonidae Števčić, 2005 in Karasawa & Schweitzer [2006] and Ng & Manuel-Santos [2007]).

Psopheticoides Sakai, 1969 (in Euryplacidae ).

DIAGNOSIS. — Carapace transversely rectangular, quadrate, subcircular, or trapezoidal ; front narrow to wide, lamellar, straight, rarely marked by median notch or projection. Dorsal surface smooth or marked with variously distinct regions. Single anterolateral tooth posterior to outer orbital angle, sometimes obsolete. Notch between frontal margin, inner edge of supraorbital border typically slight. Orbits moderately to conspicuously wide, fissure typically absent. Eye peduncles of varying length ; cornea round to elongated. Antennules fold transversely. Basal antennal article short to relatively long, subcylindrical ; lying freely in orbital hiatus, not reaching front. Thoracic sternum wide. Median sulcus on thoracic sternite 4 absent; sutures 4/5, 5/6 interrupted medially, 6/7, 7/8 interrupted medially or 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, portions of varying size left visible or not by abdomen. Cheliped (P1) fingers varying from dark to light in colour; ambulatory legs (P2-P5) compressed. Male abdomen with 6 freely articulated somites plus telson; narrower than sternum, somite 3 being narrower than thoracic sternite 7; telson slightly longer than wide. Abdominal-locking mechanism with medium-size button on edge of thoracic sternite 5 pairing with shallow socket on underside (ventral surface) of abdominal somite 6. Male opening coxal, with soft, free penis arising directly from P5 coxa but protected by sternum for a short distance (coxosternal condition). G1 slender or stout, typically with truncated tip. G2 long, typically with long flagellum (short in a few species). Female abdomen with 6 freely articulated somites plus telson ; locking mechanism with medium-size button on edge of thoracic sternite 5 in immature individuals; vulva of varying size on thoracic sternite 6, vulvar cover may be present.

REMARKS

As part of the Goneplacidae sensu Balss 1957 , the subfamilies Goneplacinae and Carcinoplacinae were traditionally separated by the shape of their respective carapaces. The typical carcinoplacine carapace, represented by Carcinoplax , is subquadrate, with orbits that are not excessively elongated (or “normal”) so that the widest breath of the carapace is at the level of the anterolateral borders, a shape often referred to as “xanthoid”. In contrast, the typical goneplacine carapace, as in Goneplax , is transversely rectangular and has its widest breadth typically at the level of the outer orbital angles as a result of conspicuously elongated orbits to accommodate long eye peduncles. An almost identical goneplacine carapace also appears among some members of the Euryplacidae (such as Frevillea A. Milne-Edwards, 1880 , and Trapezioplax Guinot, 1969 ), clearly not members of the Goneplacinae as evidenced by the morphology of their respective male abdomens, G1, and vulvae (see discussion of Psopheticoides Sakai, 1969, p. 620 ). As in other groups of brachyuran crabs, carapace shape is not always a reliable synapomorphy.

Guinot (1971: 1081, footnote) precisely explained that the separation between Carcinoplacinae and Goneplacinae was more a matter of convenience and that the distinction between the two taxa “ne sera peut-être pas justifiée dans une classification peu découpée”. Although the morphometry of the carapace conveniently separates some genera, carapace shape and the relative length of the orbits are clearly intermediate between the two extremes in the case of Psopheticus Wood-Mason, 1892 and Exopheticus n. gen. The absence of a clear distinction among other characters, such as the morphology of the male abdomen and its relation to the thoracic sternum, and the morphology of the G1 and vulva, do not support the traditional dichotomy (see Table 2).

The Carcinoplacinae was synonymized with Goneplacinae by Karasawa & Kato (2003a, b) based on the cladistic analysis of characters among recent and fossil genera included or purportedly related to the Goneplacidae . Their hypothesis is supported by the original “ Goneplacidae carcinoplaciens-gonéplaciens ( Carcinoplacinae + Goneplacinae )” line of Guinot (1969b) and more recently by Karasawa & Schweitzer (2006). The present work also supports Karasawa & Kato’s hypothesis, and the two subfamilies are thus treated as one. An alternate hypothesis is the creation of at least three subfamilies for the Carcinoplacinae (see Karasawa & Kato 2003a, b); another is the elevation of the subfamilies of the Goneplacidae to full family status, as originally done by Ortmann (1894) and more recently by d’Udekem d’Acoz (1999) and Karasawa & Schweitzer (2006) and in part by Števčić (2005). For Karasawa & Schweitzer (2006) the Goneplacidae consists of only one subfamily so in essence the Goneplacinae was raised to family status.

Five genera that have been placed at one time or another in the Carcinoplacinae or Goneplacidae are herein excluded from the Goneplacinae sensu stricto . The inclusion in the Goneplacidae of the first four genera listed below is questionable at best, but for the time being, these four genera are herein retained in the superfamily Goneplacoidea .

Bathyplax A. Milne-Edwards, 1880 , a monotypic Western Atlantic genus, has a carapace not unlike that of Carcinoplax . It has one anterolateral tooth and a conspicuous outer orbital tooth. The G1 is slender, the G2 about half the length of the G1. The vulva is round and large but not as large as in Carcinoplax , and partially covered by a vulvar cover in large females. The orbits and eyes are short. Although these characters may be found in some goneplacids, Bathyplax shows similarities to various other groups. Guinot (1969c, 1978), Manning & Holthuis (1989), and Tavares (1996) have discussed its affinities to the families Geryonidae Colosi, 1923 , and Xanthidae MacLeay, 1838 , although they did not explicitly recommend its transfer to any of these two families.

Conleyus Ng & Ng, 2003 , a monotypic Western Pacific genus, has a flattened, ridged, and bidentate carapace with superficial similarities to Intesius Guinot & Richer de Forges, 1981 , which together with Mathildella Guinot & Richer de Forges, 1981 , has been allied to the Goneplacidae . The male holotype (cl 12.2 mm, cw 16.4 mm; UF 2098) and male paratype (cl 7.1 mm, cw 9.4 mm; ZRC 2002.175) show the unusually reduced orbits, eye peduncles, and eyes ( Ng & Ng 2003: figs 2, 4A, B), which are not typical goneplacine characters and which were considered adaptations to its presence in rubble at moderate depths (30-67 m). The G1 of Conleyus ( Ng & Ng 2003: fig. 5D-F) has similarities to the stout G1 of Pycnoplax n. gen. and Thyraplax n. gen. but it is shorter, thinner, the tip is slightly flared, and the terminal spinules much smaller than in the two goneplacine genera. The G2 is long but it has a short flagellum and lacks the slightly-expanded tip with one or more spinules often seen in the G2 of goneplacines. The male abdomen is not typically triangular as in goneplacines, somites 5 and 6 being distinctively narrower than somite 4 ( Ng & Ng 2003: fig. 5D). The morphology of the vulva remains unknown since the species is known only from two males. The anterior portion of the thoracic sternum ( Ng & Ng 2003: fig. 5A) is narrower than in goneplacines and there is a complete and well developed 3/4 suture, a character absent in the Goneplacidae . Conleyus was included in the Carcinoplacinae by Ng & Ng (2003) but removed from the Goneplacidae and placed, without explanation, in the superfamily Conleyodea [sic], family Conleyidae by Števčić (2005). Ng & Manuel-Santos (2007) kept the genus in an independent family within the superfamily Goneplacoidea .

Paragalene Kossmann, 1878 , a monotypic genus from the Mediterranean Sea, has a carapace with a superficial resemblance to Carcinoplax . Somites 3 and 4 of the male abdomen are fused, however, and the long flagellum of the G2 is serrated ( Guinot 1969c: fig. 103). Guinot (1969c: 696) tentatively included the genus in the family Geryonidae Colosi, 1923 . Although Števčić (2005) kept Paragalene in Geryonidae, Karasawa & Schweitzer (2006: 55) stated that the genus “might be assigned to the Mathildellidae ” but solely on account of its carapace.

Progeryon Bouvier, 1922 , with four Indo-West Pacific species, has a carapace similar to that of geryonids. Nevertheless, all somites of the male abdomen are mobile (somites 3-5 fused and immobile in Geryonidae ) and the G1 and G2 are similar to those of some goneplacines (see Ng & Guinot 1999). Sutures 4/5 to 6/7 are incomplete, thoracic sternite 8 is not visible ventrally, and the abdomen covers the space between the P5 coxae. The systematic position of Progeryon is a controversial one (see Karasawa & Schweitzer 2006: 35, 55). More recently, it has been listed as incertae sedis in the family Goneplacidae by Karasawa & Kato (2003a), in the tribe Progeryonini of the family Geryonidae Colosi, 1923 , by Števčić (2005), and in the Progeryonidae Števčić, 2005 , by Karasawa & Schweitzer (2006). Ng & Manuel-Santos (2007) kept the genus in its own family, the Progeryonidae , within the superfamily Goneplacoidea .

Psopheticoides Sakai, 1969 , a monotypic Western Pacific genus, is being referred to the Euryplacidae . The examination of numerous specimens of Psopheticoides sanguineus Sakai, 1969 , from the Philippine Is and Tonga, all deposited at ZRC and MNHN, show a slender male abdomen, a deep steno-abdominal cavity, a slender G1 with pointed tip and armed with spinules, a short G2 that is much shorter than the G1, a relatively long penis that lies in a concave thoracic sternite 8 before joining the G1, a relatively narrow female abdomen where the distal border of the thoracic sternites are left uncovered, and a thoracic sternite 8 that is concealed from dorsal view. The examination of these specimens is part of an ongoing revision of the Euryplacidae and related genera.