Goneplax clevai, Guinot & Castro, 2007

Guinot, Danièle & Castro, Peter, 2007, A new species of Goneplax Leach, 1814 (Crustacea, Decapoda, Brachyura, Goneplacidae) from the south Atlantic and the western limits of the Indo-West Pacific region, long confused with G. rhomboides (Linnaeus, 1758), Zootaxa 1577 (1), pp. 17-31 : 19-26

Goneplax clevai n. sp.

( Figures 1–3 , 4A )

Goneplax angulata . — Stebbing 1902: 15; 1910: 312; 1914: 264, as Goneplax angulatus [ South Africa]; Doflein 1904: 117 [ South Africa]; Odhner 1923: 26 [ South Africa]; Barnard 1950: 283, fig. 53a; 1954: 126; 1955: 4 [in list] [ South Africa]; Capart 1951b: 168, fig. 64, pl. 3, figs. 4, 10 [ Gabon, Democratic Republic of Congo, Angola]; Monod 1956: 354 [refs.]; Kensley 1969: 151, 177 [in lists]; 1981: 46 [in list] [ South Africa]; Richardson et al. 2000: table 1 [ South Africa]; Strømme et al. 2004: annexe 1 [ Namibia]. (Not Goneplax angulata ( Pennant, 1777) , junior synonym of G. rhomboides (Linnaeus, 1758) .

Goneplax rhomboides . — Guinot & Ribeiro 1962: 63 [ Angola]; Le Loeuff & Intès 1968: 72, table 1 [ Ivory Coast]; Crosnier 1970: 1216 [ Angola]; Gaudêncio & Guerra 1981: 53 [ Angola]; Manning & Holthuis 1981: 163 [pro parte: Angola]; Macpherson 1983: 31, only fig. 18A, B [coast of Namibia; fig. 18C, D = G. rhomboides ]; 1991: 410, fig. 7, table 1 [distribution in Namibia]. (Not Goneplax rhomboides (Linnaeus, 1758) .

[ Carcinoplax ] barnardi . — Guinot 1989 pro parte: 315, fig. 45. (Not Carcinoplax barnardi Capart, 1951 ).

Type material. Holotype, male 24 x 40 mm, Angola, South Atlantic , A.S. 29, 6°18’S – 11°34’E, 140–150 m, 17– 21.09.1948, Capart det. Goneplax angulata ( IRSNB 13599 ) ( Figure 1 ).

Paratypes – See Capart’s material in Other material examined.

Type locality. Angola, South Atlantic , A.S. 29, 6°18’S – 11°34’E, 140–150 m.

Other material examined. Ivory Coast: Abidjan, Grand Bassam , trawl, 250 m, 23.12.1966, Le Loeuff & Intès (1968) coll., det. G. angulata : 1 female 22 x 35.8 mm ( MNHN-B19812 ) . Abidjan, “ Trou sans fond”, 300–400 m, clam grab, Le Loeuff & Intès coll. 14.11.1969, det. G. angulata : 1 male 18 x 29 mm (MNHN- B19813) . Abidjan, East Fresco , shrimp trawl, 68 m, Le Loeuff & Intès coll., 23.08.1968, det. G. angulata : 1 female, damaged ( MNHN-B19814 ) . Congo (Democratic Republic): Off Pointe Noire , 5°00’S – 11°22’E, trawl, 190–210 m, sandy mud, 15.03.1967, A. Crosnier coll. and det. Carcinoplax barnardi : 1 female 25 x 38.3 mm ( MNHN-B10707 ) . Off Pointe Noire , 5°00’S – 11°23’E, dredge, 145 m, mud, 18.09.1969, A. Crosnier coll. and det. Goneplax rhomboides : several juveniles ( MNHN-B10197 ) . Off Pointe Noire , 04°58’S – 11°24’E, trawl, 120 m, sandy mud, 13.12.1966, A. Crosnier coll. and det. Goneplax angulata : 1 male about 13 x 20.5 mm, damaged ( MNHN-B10164 ) . Off Pointe Noire , 04°56.3’S – 11°27.6’E, 22.08.1969, A. Crosnier coll. and det. Goneplax rhomboides : several juveniles ( MNHN-B10195 ) . Angola: Male 23 x 38.5 mm (dry) ( Figure 1A ) ( MNHN-B30224 ) . Namibia: North coast, Exp. Benguela II, E. Macpherson coll. and det. (1983: 31) Goneplax rhomboides : stn P2 , 17°44’S – 11°14’E, 70 m, 28.07.1980: 1 male 17 x 27 mm; stn P4, 18°17’S – 11°29’E, 309 m, 29.07.1980: 1 male 15.5 x 24.5 mm. South Africa: Table Bay , 23–07.1894, 9–15 m, M. Weber leg., det Goneplax angulata : 3 small males ( ZMA) . Knysna, 1894, M. Weber leg., det. Goneplax angulata : 1 male 31 x 49 mm ( ZMA) . Algoa Bay, H.A. Spencer coll.: 4 males 21.5 x 34.8 mm, 24.3 x 39.0 mm, 24.4 x 39.3 mm, 25.1 x 41.3 mm ( NHM 1896.5.19.5.8). Port Elizabeth, H. A. Spencer coll.: 1 male 20.4 x 34.1 mm ( NHM 1891.10.22.2). Port Elizabeth , local trawlers , 01.12.2003: 1 male 21.3 x 35.3 mm ( Figures 2B , 3 ) ( ZRC 2004.0700 ) . 26 km northeast of Bird I., 73 m, Natal Government Museum leg.: 1 male ( NHM 1917.619.29) .

Capart’s South Atlantic material from Gabon, D.R. of Congo, and Angola (see Capart 1951a), Capart (1951b) det. Goneplax angulata (IRSNB) . Congo (D. R.): A.S.15, 5°50’S – 11°32’E, 215–220 m, 22– 23.08.1948: 1 male 19.5 x 31.0 mm ( IRSNB 13597).

Gabon: A.S.26, 3°57’30”S – 10°36’30”E, 85 m, 06.09.1948 (erroneously as 1949 in Capart’s description; see Capart 1951 a, 1951b): 1 juv., incomplete ( IRSNB 13598). Angola: A.S.29, 6°18’S – 11°34’E, 140–150 m, 17– 21.09.1948: holotype male 24 x 40 mm ( IRSNB 13599) ( Figure 1 ). A.S.63, 6°31’S – 11°45’E, 170 m, 10– 11.11.1948: paratype male 24 x 38 mm ( Figure 4A ) ( MNHN-B 19584). A.S.110, 16°20’S – 11°27’E, Baía dos Tigros, 110 m, 27.01.1949: paratypes 5 males 9.5 x 16 mm, 11 x 17 mm, 12 x 19 mm, 12.5 x 20.5 mm, 13 x 21.3 mm ( IRSNB 13601).

A.S.133, 6°20’S – 11°35’30”E, 200– 150 m, 22.02.1949: paratype 1 male 20.5 x 33 mm ( IRSNB 13602 ) .

Description. Carapace ( Figures 1 , 2 , 3A ) rectangular, much wider than long. Anterolateral border long, convex. Dorsal surface slightly convex, glabrous, smooth, except for rare punctuations, more marked laterally; no clear indication of regions, only branchiocardiac groove distinct; two weak transverse ridges, one anterior between anterolateral spines, more posterior second one. Posterolateral border wide. Front lamellar, truncate, deflected downwards, not marked by median notch. A weak angle between front, inner edge of supraorbital border. Supraorbital border sinuous, with obsolete fissure, bordered by raised, finely granular edge, curved along front. Outer orbital tooth triangular or acute, straight, anteriorly directed. Second anterolateral tooth ( Figure 4A ) always present, well developed, acute-tipped, anteriorly curved, may be more laterally directed. Suborbital border without fissure, bordered by marked denticles, short, rounded inner tooth. Posterolateral border short, straight, obliquely directed. Eye peduncles only moderately long (0.8 front length), cornea swollen, reniform ( Figures 1 , 2 , 3A , 4A ; see Guinot 1989: fig. 45, as [ Carcinoplax ] barnardi ). Posterior margin of pterygostomial crest granular; pterygostomial ridge smooth.

Chelipeds ( Figures 1 , 2 ) unequal, enlarged, dimorphic in large males; equal, homomorphic in females, small males; elongated merus, propodus. Fingers slender, long, much shorter than propodus; irregular teeth on both prehensile borders; on major cheliped of males fingers separated by proximal gap, prehensile border of dactylus with proximal molariform tooth; both prehensile borders joining in females. Major cheliped in large males greatly enlarged (total length of extended chelipeds about 30 mm in largest male); merus considerably longer than carapace length; can reach nearly 5 times CL (see Abelló & Sardá 1982: fig. 4b, d; Ungaro et al. 2001), distal portion of propodus widened, proximal portion of fixed finger forming a strong concavity, and prehensile borders separated by a wide proximal gap; minor cheliped with weak proximal gap. Straight, spiniform tooth on inner (dorsal), proximal margin of carpus; smaller tooth on outer (ventral), distal margin. Large, acute-tipped tooth on mid-dorsal margin of merus.

P2–P5 relatively short, stout; subdistal acute spine on dorsal margin of merus; few long, simple setae along inner, outer margins of merus, carpus, propodus; P2–P5 dactyli long, slender, each with marginal carinae.

Male abdomen ( Figure 3B ) triangular. Somites 1, 2 narrower than extended somite 3, leaving large portion of thoracic sternite 8 visible, somite 3 separated from P5 coxa by exposed proximal portion of penis; telson triangular, wider than long. G1 ( Figure 3C ) slender, apex pointed, with obtuse denticles; G2 ( Figure 3D ) slightly longer than G1, slender, slightly curved flagellum shorter than proximal part, slightly expanded, bifid apex with thick, long spinule plus smaller one.

Colour ( Figure 2 ). Colour of live G. clevai remains unknown. Barnard (1950: 285, as G. angulata ) indicated: “pale pink, or salmon, or pinky-cream, carapace and chelipeds more or less vermiculate or mottled.” The freshly collected specimens of Capart (1951b, as G. angulata ) showed a purplish anterior half of the carapace, brown-red chelipeds, and violaceous and partially black fingers. In alcohol specimens, the dactylus of both chelipeds of males has a long, dark-coloured subdistal spot; there is only a small dark spot on fixed finger; in the females the spot is much smaller, more distal. The anterior portion of the carapace of the relatively recently collected and well preserved ZRC specimen ( Figure 2B ) had irregular, curved, purple-pink reticulations, the rest being whitish; the dorsal surface of the chelipeds and eye peduncles were light purple-pink; fingers of chelipeds pink except whitish tips; P3–P5 whitish. The sinuous delimitation between the coloured and white portions of dorsal surface of carapace corresponds to the cervical groove (with gastric pits), the junction of antero- and postero-lateral margins of carapace (in Goneplax ). Still coloured specimens that were examined generally had a reddish anterior half of the carapace and chelipeds. Discoloured specimens in the collections still show this delimitation on dorsal surface of carapace ( Figure 2A ).

Etymology. Dedicated to Régis Cleva, in recognition of his valuable work as curator of the decapod crustacean collection in the MNHN, Paris.

Distribution. Known from the western coast of Africa from Ivory Coast to the Indian Ocean coast of KwaZulu-Natal in South Africa, where it is “one of the commonest crabs on the Agulhas Bank” ( Barnard 1950: 285, as Goneplax angulata ). Wide bathymetric distribution, approximately 10– 700 m.

It is not known if G. clevai n. sp. is a burrower like G. rhomboides , which is known to dig shallow, complex and branching burrows in muddy, sometimes sandy, bottoms at depths of up to 100 m, but probably also at depths of 300–700 m ( Rice & Chapman 1971; Atkinson 1974, 1975; Atkinson & Froglia 1999; Parry et al. 2002). As in G. rhomboides , which has been found in the stomach of skates and rays (see Monod 1956; Farias et al. 2006), G. clevai is a component of the diet of marine animals, fishes in particular (see Richardson et al. 2000: table 1; Ebert & Cowley 2003, table 1, as Goneplax rhomboides ).

Remarks. Goneplax clevai was recorded from South Africa by Stebbing (1902: 15; 1910: 312; 1914: 264, as Goneplax angulata ) and Doflein (1904: 117, as Goneplax angulata ) and was quoted in subsequent lists ( Kensley 1969: 151, 177; 1981: 46, as Goneplax angulata ). Odhner (1923: 26, as G. angulata ), who had examined 13 adults and seven juveniles from South Africa, indicated that, by comparison to 40 specimens of G. angulata from the Mediterranean, their second lateral spine was always well marked and as strong as the outer orbital tooth, independently from age and sex. Barnard (1950: 285, fig. 53a, as G. angulata ), who examined numerous South African specimens, noted the constant presence of a well-developed second spine on the antero-lateral border of the carapace (instead of the small spine, knob or light swelling characteristic of the Mediterranean G. rhomboides ), and published a figure that clearly does not correspond to G. rhomboides . All South African material must be referred to as G. clevai n. sp.

Capart (1951b: 168, fig. 64, pl. 3, figs. 4, 10, as G. angulata ), who regarded G. rhomboides and G. angulata as distinct “varieties” from the Mediterranean Sea and Atlantic respectively, was the first to discern the special characters of his South Atlantic material but did not recognized it as distinct from G. rhomboides . His description and figures clearly correspond to G. clevai n. sp.

The material from Senegal referred to as G. rhomboides by Monod (1956: 354, figs. 462–465) corresponds to G. rhomboides . In contrast, the material from Angola referred to as G. rhomboides by Guinot & Ribeiro (1962: 63) and Crosnier (1970: 1216; his quotation of “ Gabon ” also concerns G. clevai n. sp.) corresponds to G. clevai n. sp. The male specimen from Ghana referred to (without figures) as G. rhomboides by Forest & Guinot (1966: 86) unfortunately could not be found in the MNHN collection, so its identity remains uncertain. The extent of the geographical overlap between G. rhomboides and G. clevai remains unknown. Manning & Holthuis (1981), who briefly commented on the observations of Capart (1951b), and Monod (1956) were mostly concerned by the problem of the identities of G. angulata and G. rhomboides . Consequently, they did not separate their northern material (the real G. rhomboides ) as different from their Ivory Coast and Angola material, which most likely included G.clevai n. sp.

Macpherson (1983) compared Mediterranean specimens ( Macpherson 1983: fig. 18C, D, the true G. rhomboides ) to material from Namibia ( Macpherson 1983: fig. 18A, B), which corresponds to G. clevai n. sp. But the question of the separation between G. rhomboides and G. angulata prevented him from recognizing the new species, so the Namibian material was referred to as G. rhomboides .

D’Udekem d’Accoz and Guinot (in d’Udekem d’Accoz 1999: 242) suggested the presence of a new southern African species of Goneplax . A new name, G. clevai , is given herein because none of the synonyms of G. rhomboides , viz. Cancer angulatus Pennnant, 1977 , Ocypoda bispinosa Lamarck, 1801 ( Lamarck 1801: 150) , Ocypoda longimana Latreille, 1803 ( Latreille 1803: 44, pl. 6, fig. 3), and Gelasimus bellii Couch, 1838 ( Couch 1838: 72) , corresponds to the new southern African species.

Goneplax clevai n. sp. is distinguished from G. rhomboides by a more quadrate carapace, with lateral borders only weakly converging posteriorly; a convex anterolateral border; an always spiniform second anterolateral tooth; dorsal surface of carapace with two transversal ridges; eye peduncles that are shorter than in G. rhomboides , and a swollen cornea (see below).

Another species, Carcinoplax barnardi Capart, 1951 , is found along the coast of West Africa, from Western Sahara to Angola, with records from Senegal, Ivory Coast, Nigeria and Gabon ( Capart 1951b: 170, fig. 65, pl. 3, figs. 5, 12; Monod 1956: 340, 351, figs. 456–461; Maurin 1968: 484; Guinot 1969 b: 526; 1971: 1081; Manning & Holthuis 1981: 160). It has been recorded from depths of 200 to 586 m. Goneplax clevai n. sp. and Carcinoplax barnardi are thus sympatric, probably in several regions of the west African coast that extends from Senegal to Angola. Goneplax clevai extends further south than Carcinoplax barnardi , which does not extend to the Indian Ocean coast of South Africa.

Carcinoplax barnardi (see Capart 1951b: fig. 65; Monod 1956: fig. 456) can be easily distinguished from both G. rhomboides and G. clevai n. sp. by several characters: anterolateral borders of the carapace clearly rounded and highlighted by conspicuously pointed tubercles located on the subhepatic region (straight or nearly straight and smooth in G. rhomboides and G. clevai ); second anterolateral spine farther apart from the short outer orbital tooth and having the shape of a long, acute and recurved spine (closer to the marked outer orbital tooth, and as a small spine, knob or obsolete in G. rhomboides , as a smaller spine obliquely directed in G. clevai ); small orbit (better developed in G. clevai and G. rhomboides ); very short and thick eyestalks, not completely filling orbit (longer in G. clevai , much longer and narrower in G. rhomboides ; see below); front straight (deflected downwards in G. clevai and G. rhomboides ). The chelipeds of G. clevai show strong sexual dimorphism (see Abelló & Sardá 1982; Ungaro et al. 2001; as G. rhomboides ), with a marked positive allometric growth in the male chelipeds. The major cheliped has a long merus and propodus, an enlarged palm, and the fingers are considerably gaping in large individuals. Carcinoplax barnardi shows a similar sexual dimorphism of the chelipeds. G. clevai n. sp. is also easily distinguished from G. rhomboides and Carcinoplax barnardi by the length of its eye peduncles, which is somewhat intermediate between the two: 0.8 of the front length ( Figures 1 , 2 , 3A , 4A ; Barnard 1950: fig. 53a, as G. angulata ), much less long than in G. rhomboides ( Figure 4B ) (where it is as long or slightly longer than the front length) but much longer than that of C. barnardi (0.4 of the length of the front; see Capart 1951b: fig. 65).

The armature of the anterolateral border varies only weakly among the specimens of G. clevai n. sp. examined ( Figures 1 , 2 , 3A , 4A ). The acute-tipped and curved second anterolateral tooth is only more or less laterally directed so that the character is reliable enough to differentiate it from G. rhomboides . Conversely, there is much variation in the shape of the anterolateral borders, outer orbital and anterolateral teeth in G. rhomboides . In G. rhomboides the second tooth is either an acute spine ( Figure 4B ; see Ingle 1980: fig. 50, pl. 17a; Falciai & Minervini 1992: 239, pl. 17, fig. 1; 1996: 253, pl. 17, fig. 1, as G. rhomboides ), reduced to a mere knob (see d’Udekem d’Acoz 1986: fig. 31, as G. rhomboides ), or a slight swelling (see Bouvier 1940: pl. 11, fig. 2, as G. angulata ) or is practically absent (see Latreille 1803: pl. 6, fig. 3, as Ocypoda longimana ; Desmarest 1823: 244, pl. 13, fig. 2, as Gonoplax rhombo ï des; Roux 1828 –1830, pl. 9, as Gonoplax rhomboidalis ; Zariquiey Alvarez 1968: fig. 138a, b, as G. rhomboides ). In Carcinoplax barnardi the second anterolateral tooth is always a long and acute spine, and thus appears to be a reliable character.

There are differences in colour between the three species. G. clevai n. sp. ( Figure 2 ) shows two differently coloured portions on the dorsal surface of the carapace, the anterior half red or pink (may persist in specimens preserved for a considerable amount of time), the rest being whitish. G. rhomboides has “yellow to pale red, sometimes fringed with violet” carapace and “yellow to orange” chelipeds and ambulatory legs ( Ingle 1980: 109) or “carapace yellowish to pale red, sometimes tinged with violet; chelipeds and pereopods yellow to orange” ( Moyse & Smaldon 1990). Carcinoplax barnardi was described as “rose bistre” (dark-brown pink) ( Capart 1951b: 172). In the three species, the dactylus of both male chelipeds has a dark–coloured, elongated spot.

Goneplax rhomboides is known throughout the Mediterranean Sea (where it is frequent and common from 50 to 700 m, see Sardá et al. 1982; Abelló et al. 1988; Abelló & Corbera 1996; d’Udekem d’Acoz 1999; Abelló et al. 2002) and the Atlantic coasts of Europe (fairly common on all British coasts [see Clark 1986]; rare in the North Sea). It is also known from the Netherlands ( Ruijter 2004, Oosterbaan 2004), and from the Bay of Biscay to Madeira and along the northern coasts of Africa, from the Canary Islands (probably also from the Cape Verde Islands), to at least Senegal. Its bathymetric range is wide, from sublittoral to 600– 700 m.

It is not certain if G. clevai n. sp. is sympatric with G. rhomboides along parts of the northwest African coast. There are records of the presence of G. clevai along the African coasts: Ivory Coast (see Material Examined), Gabon ( Capart 1951b), Democratic Republic of Congo, Namibia ( Macpherson 1983, 1991) and Angola. A hypothesis is that G. rhomboides is replaced in the south by G. clevai n. sp. The limit between the two species is difficult to estimate, but it is at least as far north as Ivory Coast (there are no certain records of G. rhomboides at this latitude) and perhaps further north. Goneplax rhomboides is never present on the Indian Ocean coast of South Africa. Conversely, G.clevai extends beyond the southeastern boundaries of the Atlantic Ocean into the Indo-West Pacific region, as is the case with several crab species ( Kensley 1969: 177, table).

Goneplax clevai n. sp. is sympatric with Carcinoplax barnardi along West Africa, as in the case of Senegal, Congo (from Pointe Noire G. clevai was collected at 5°00’S – 11°23’E, 145 m, and C. barnardi at 5°00’S – 11°29’E, 405–410 m and °06’S– 11°26’E, 345–355 m) and Angola, where the two species may have been confused. Re-identification of the material from these regions deposited in museums would be needed to determine the distribution of the three species.

Goneplax sigsbei (A. Milne-Edwards, 1880) , from the western Atlantic Ocean, is distinguished from G. clevai n. sp., the other species of Goneplax ( G. rhomboides ) and Carcinoplax barnardi by anterolateral teeth that are very close to the outer orbital teeth, shorter and stouter G1, and long and conspicuously curved G2 (see Rathbun 1918: pl. 4, figs. 2, 4; A. Milne-Edwards & Bouvier 1923: fig. 3, pl. 6, fig. 2, as Frevillea sigsbei ; Guinot 1969 b: 520, figs. 68, 71, 72; 1971: 1082; Williams 1984: 433, fig. 345). In G. sigsbei the eye peduncles are thick and relatively short, considerably shorter than in G. rhomboides ( Figure 4B ) and shorter than G. clevai ( Figure 4A ), but not as short as in Carcinoplax barnardi .

Figures

FIGURE 1. Goneplax clevai n. sp., holotype male, 24 x 40 mm, Capart det. Goneplax angulata, South Atlantic, Angola, A.S.29, 6°18’S–11°34’E, 140–150 m (IRSNB 13599).

FIGURE 2. Goneplax clevai n. sp. A, male, 23 x 38.5 mm (dry) Angola (MNHN-B30224); B, male, 21.3 x 35.3 mm, Algoa Bay, South Africa (ZRC 2004.0700).

FIGURE 3. Goneplax clevai n. sp., male, 21.3 x 35.3 mm, Algoa Bay, South Africa (ZRC 2004.0700); A, carapace; B, abdomen; C, right G1, ventral view and details of apex; D, right G2, ventral view and details. Scale bars: 5 mm.

FIGURE 4. Eye and anterolateral border of the carapace. A, Goneplax clevai n. sp., paratype male, 24 x 38 mm, Angola, A.S. 63, 6°31’S–11°45’E, 170 m, Capart det. G. angulata (MNHN-B19584); B, G. rhomboides (Linnaeus, 1758), male, 20 x 34 mm, Bay of Biscay, “Charcot” 1969, stn 10, 100 m (MNHN-B30227).