Goneplax Leach, 1814

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 : 685-687

Genus Goneplax Leach, 1814 , emend.

Goneplax Leach, 1814: 393 , 430. — Ortmann 1898: 1176 [in list] (part). — Tesch 1918: 181 (part). — Rathbun 1897: 167 [nomenclature]; 1918: 25 [diagnosis, key to species] (part). — Stebbing 1902: 15 [discussion]. — Sakai 1939: 562 [in key], 563; 1976: 537 (part). — Barnard 1950: 282 [in key], 283 [diagnosis] (part). — Balss 1957: 1656 (part). — Glaessner 1969: R524 (part) [diagnosis]. — Guinot 1969b: 520 [discussion]; 1971: 1081 [list of species] (part). — Serène 1964: 189, 190 (part), 190 [key to species]. — Zariquiey Álvarez 1968: 413. — Manning & Holthuis 1981: 163 [synonymy, references]. — Karasawa & Kato 2003b: 130 [in list], 140 [in list], 141 [in table] (part). — Komatsu & Takeda 2003: 1243 (part). — Karasawa & Schweitzer 2006: 40 (part). — Guinot & Castro 2007: 18 [discussion]. — Ng & Manuel-Santos 2007: 42 [discussion].

Goneplat [sic] Leach, 1814: 393, 430 (invalid original spelling of Goneplax ; see Rathbun 1897: 167; Melville & Smith 1987: 99).

Gonoplax [sic] Leach, 1816a: 409, 413. — De Haan 1833: 6, 19 [as subgenus]. — Dana 1851: 285 [diagnosis]; 1852: 310 [diagnosis], 1493 [in list]. — H. Milne Edwards 1852: 162. — Miers 1886: xiv, 237 [in list], 245 (part). — Alcock 1900: 293 [in list], 316 (part). — Lebour 1928: 487 [in key], 488, 491 [in key] [larvae] (invalid spelling of Goneplax Leach, 1814 ; see Rathbun 1897: 167; Melville & Smith 1987: 99).

Not Gonoplax [sic] – Miers 1886: xiv, 237 [in list], 245 (part) (= Hadroplax n. gen.).

Not Goneplax – Tesch 1918: 181 (part). — Serène 1964: 189, 190 [key to species]; 1968: 89 [list of species] (part). — Guinot 1969b: 522 [discussion]; 1971: 1081 [in list] (part). — Komatsu & Takeda 2003: 1244 [in list] (part) (= Hadroplax n. gen., Neogoneplax n. gen., and Microgoneplax n. gen.).

Not Goneplax – Dai et al. 1986: 376 [key to species]. — Dai & Yang 1991: 406 (= Neogoneplax n. gen., and Singhaplax Serène & Soh, 1976 ).

Not Goneplax – Takeda 1973b: 51 (= Singhaplax Serène & Soh, 1976 ).

TYPE SPECIES. — Ocypoda bispinosa Lamarck, 1801 (gender feminine). Name placed in Official List of Names in Zoology (with the officially designated type species) in Opinion 85, Direction 37 (see Melville & Smith 1987: 99).

EXTANT SPECIES INCLUDED . — Goneplax rhomboides ( Linnaeus, 1758) ; G. barnardi ( Capart, 1951) n. comb.; G. clevai Guinot & Castro, 2007 ; G. sigsbei (A. Milne- Edwards, 1880).

All species are restricted to the Western and Eastern Atlantic regions; one species ( G. rhomboides ) is also found in the Mediterranean Sea. Goneplax clevai is found in the Eastern Atlantic and the southeastern coast of South Africa, thus ranging into the Indo-West Pacific region.

FOSSIL SPECIES INCLUDED ( Karasawa & Kato [2003b]). — Seven species are listed by Karasawa & Kato (2003b): Goneplax arenicola (Glaessner, 1960) , G. craverii Crema, 1895 , G. formosa Ristori, 1886 , G. meneghinii Ristori, 1886 , G. gulderi Bachmayer, 1853 , G. saccoi Crema, 1895 , and Goneplax sp. cf. G. saccoi Crema, 1895 .

SPECIES NOT INCLUDED IN GONEPLAX . — Goneplax maldivensis Rathbun, 1902 (in family Euryplacidae Stimpson, 1871 ; Otmaroplax maldivensis nomen nudum in Števčić 2005).

Goneplax marivenae Komatsu & Takeda, 2003 (and junior synonym, Goneplax megalops Komatsu & Takeda, 2003 ; in Goneplacoides n. gen.).

Goneplax nipponensis Yokoya, 1933 (?in Hadroplax n. gen.).

Goneplax renoculis Rathbun, 1914 (in Neogoneplax n. gen.).

Goneplax serenei Zarenkov, 1972 (in Paragoneplax n. gen.).

Goneplax sinuatifrons Miers, 1886 (in Hadroplax n. gen.).

Goneplax wolffi Serène, 1964 (in Singhaplax Serène & Soh, 1976 ).

DIAGNOSIS. — Carapace ( Fig. 27A, B ) transversely rectangular to trapezoidal, much wider than long; widest at anterolateral teeth posterior to conspicuous outer orbital teeth; front slightly deflected ventrally, slightly concave or straight, not marked by slight median notch or projection. Notch between front, inner edge of supraorbital border distinct, slight, or absent; orbits wide, greatly expanded distally (moderately expanded in G. barnardi n. comb.); supraorbital borders conspicuously sinuous; suborbital borders sinuous, with slight, wide obtuse inner tooth not visible dorsally; anterolateral borders short, straight or slightly convex. Dorsal surface of carapace smooth, with slight horizontal ridges, moderately convex, without clear indication of regions. Outer orbital angle with conspicuous, acute tooth; single acute anterolateral tooth on each side of carapace (short, obtuse, or obsolete in some specimens of G. rhomboides ; see Macpherson 1983: fig. 18). Basal antennal article short, distalmost (third) article reaches front. Eye peduncles ( Fig. 27A, B ) long, shorter to as long as front (0.4-1.0 front width); cornea spherical to elongated. 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. Cheliped fingers ( Fig. 27A, B ) long, slender, straight or slightly curved, shorter than elongated propodus; variable portion of dactylus darker in colour, tip light; carpus with tooth on inner margin (absent in large individuals). Dorsal margins of ambulatory leg (P2-P5) meri ( Fig. 27A, B ) with acute distal tooth; dactyli slender, with carina on each side, setose. Male abdomen with 6 freely-movable somites plus telson, narrowly triangular, 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 relatively large portion of thoracic sternite 8 visible ( Guinot 1969b: figs 63, 64, 68). G1 ( Capart 1951: figs 10-12; Türkay 1976: fig. 28; Guinot 1969b: fig. 71a, b; 1989: fig. 46A, as Carcinoplax barnardi ; Guinot & Castro 2007: fig. 3C) long, slender, thin, slightly sinuous, only slightly broadened proximally; pointed, thin tip. G2 ( Capart 1951: figs 4, 5, 12; Guinot 1969b: fig. 72; 1989: fig. 46B, as Carcinoplax barnardi ; Guinot & Castro 2007: fig. 3D) slender, slightly longer or slightly shorter than G1, flagellum shorter than proximal part (peduncle), curved; slightly-expanded tip with 1 or 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 round, extending from oblique 5/6 suture to 6/7 suture or to median portion of thoracic sternite 6, covered by soft membrane, vulvar cover absent.

REMARKS

Examination of numerous specimens of the type species of Goneplax , G. rhomboides ( Linnaeus, 1758) , plus three other species sharing several important characters with the type species, clearly shows that Goneplax should be restricted to these four species. All four species are found in the Atlantic Ocean although one species ( G. rhomboides ) is also found in the Mediterranean Sea, while another ( G. clevai Guinot & Castro, 2007 ), spans the Atlantic and Indian Ocean coasts of Africa and hence is found in both the Eastern Atlantic and Indo-West Pacific regions.

The implication that Goneplax should be restricted to species found outside the Indo-West Pacific region was first expressed by Guinot (1969b: 520). Serène & Vadon (1981: 126) suggested the creation of “one or two new genera” for two Indo-West Pacific species, Goneplax renoculis Rathbun, 1914 , and G. sinuatifrons Miers, 1886 . Serène & Soh (1976) had previously erected the genus Singhaplax for two Indo-West Pacific species previously attributed to Goneplax : G. nipponensis Yokoya, 1933 , and G. ockelmanni Serène, 1971 (see Remarks for Singhaplax below). More recently, Števčić (2005) included two of the Indo-West Pacific species of Goneplax sensu lato ( G. maldivensis Rathbun, 1902 , actually a euryplacid, and G. sinuatifrons ) in two new genera. The taxa were listed without giving descriptions or definitions to differentiate them from other genera, therefore they must be considered nomina nuda ( ICZN 1999: Article 13a).

The six Indo-West Pacific species of Goneplax sensu stricto remaining after the description of Singhaplax Serène & Soh, 1976 , are herein placed in five separate genera, Goneplacoides n. gen., Hadroplax n. gen., Microgoneplax n. gen., Neogoneplax n. gen., and Paragoneplax n. gen. A seventh species, G. maldivensis , is being placed in the family Euryplacidae .

The five new genera, as well as Ommatocarcinus White, 1852 , and Neommatocarcinus Takeda & Miyake, 1969 , share with Goneplax sensu stricto and Singhaplax elongated orbits and eye peduncles and wide, transversely rectangular and relatively short carapaces with conspicuous, often acute outer orbital teeth. Also included in this group is Frevillea A. Milne-Edwards, 1880 , and G. maldivensis , both euryplacids. The use of carapace shape to separate between Goneplax sensu stricto and Carcinoplax sensu stricto is only a matter of convenience (see Remarks for subfamily Goneplacinae above). The evolution of elongated eye peduncles among brachyuran crabs was suggested by Barnes (1968) as an adaptation to a burrowing mode of life and the avoidance of predators while feeding on the surface of the sediment. Other characters that separate Goneplax sensu stricto from the six Indo-West Pacific genera containing species that were formerly included in Goneplax sensu lato are summarized in Table 4.

Rathbun (1897: 167) clarified the validity of the original name Goneplax over Goneplat or Gonoplax , which are considered typographical errors (also see Melville & Smith 1987: 99).

Figures

FIG. 27. — A, Goneplax rhomboides (Linnaeus,1758), ♂, cl 21.6 mm, cw 34.7 mm, Shoalstone Point, Brixham, Devon,UK, D. George et al. coll., 18 m (BMNH 1981.539); B, Goneplax barnardi (Capart, 1951) n. comb., ♂, cl 14.1 mm, cw 25.1 mm, off northern coast of Angola, Campagne ZAIANGO-BIOL 2, stn CP 09, 360-367 m (MNHN-B 27933).