Carcinoplax jugum, Ng & Castro, 2020

Ng, Peter K. L. & Castro, Peter, 2020, A revision of Carcinoplax abyssicola (Miers, 1885) and seven related species of Carcinoplax H. Milne Edwards, 1852, with the description of two new species and an updated key to the genus (Crustacea, Decapoda, Brachyura, Goneplacidae), Zoosystema 42 (17), pp. 239-284 : 272-275

Carcinoplax jugum n. sp.

( Figs 21 A-I; 22 A-J; 25 Q-T)

urn:lsid:zoobank.org:act:AF26AE84-ADE8-4F9A-9A41-BA26DEAFE781

TYPE MATERIAL. — Holotype. Philippines • ♂, 45.5 × 33.6 mm; Philippines ; ZRC 2004.0777 .

Paratypes. Philippines • 1 ♀, 25.7 × 33.8 mm; Bohol, Balicasag I., off Panglao I., tangle nets of local fishermen; 09°31’00.2”N, 123°40’50.5”E; 28.XI.2001; ZRC 2001.0528 • 1 ♂, 24.2 × 32.8 mm; same location as ZRC 2002.0528; 50-500 m depth; ZRC 2001.0973 • 3 ♀, 23.3 × 31.4 mm, 24.9 × 33.4 mm, 27.0 × 35.7 mm, 3 ♂, 13.8 × 19.6 mm, 13.9 × 19.9 mm, 17.2 × 22.2 mm; same location as ZRC 2002.0528; 25-30.VII.2003; ZRC 2004.0750 • 1 ♀, 4 ♂, largest 35.9 × 48.4 mm, smallest 13.6 × 18.9 mm; same location as ZRC 2002.0528; 25-30. VII.2006; ZRC 2001.0845 • 2 ♀, 23.9 × 30.5, 26.8 × 35.3 mm; same location as ZRC 2002.0528; ZRC 2004.0730 • 6 ♀, largest 31.7 × 41.4 mm; same location as ZRC 2002.0528; 200-300 m depth; ZRC 2002.0655 • 1 ♀, 25.1 × 32.5 mm; PANGLAO 2005, stn CP2343, off Pamilican I.; 09°27.4’N, 123°49.4’E; 273-356 m depth; 23.V.2005; ZRC 2006.0217 • 2 ♂, 38.5 × 50.5, 41.4 × 63.0 mm; Maribohoc Bay ; coll. J. Arbasto, VII.2004 to. V.2005; ZRC 2018.1432 • 1 ♀, 26.8 × 35.2 mm, 1 juvenile ♀, 11.0 × 14.2 mm; PANGLAO 2005, stn CP2359, Bohol Sea; 08°49.9’N, 123°34.9’E; 437-476 m depth; 26.V.2005; ZRC 2018.1433 • 1 juvenile ♀, 13.8 × 18.0 mm; PANGLAO 2005: stn CP2406, Maribohoc Bay , 9°40.6’N, 123°46.8’E; 334-387 m depth; 1.VI.2005; ZRC 2018.1434 • 1 ♀, 30.0 × 40.2 mm, 1 ♂, 23.7 × 31.4 mm; PANGLAO 2005, stn PN1, tangle nets; 09°31’00.2”N, 123°40’50.5”E; 29.V.2004; ZRC 2004.0777 .

TYPE LOCALITY. — Philippines, Bohol, Balicasag I., off Panglao I.; PANGLAO 2004, stn P4, tangle nets of local fishermen.

DIAGNOSIS. — Carapace ( Figs 21A, B ; 22A, B ) quadrate, slightly wider than long (1.3 × wider than long in holotype); slightly convex, marked by two distinct transverse elevations across cardiac, gastric regions. Front ( Figs 21C, D ; 22C, D ) slightly sinuous, slight oblique notch between front, inner edge of supraorbital border. Conspicuous, salient ocular margins, subocular tooth. Triangular, elevated tooth on outer orbital angle; two slender, acute-tipped anterolateral teeth on each side of carapace. Short granules on subhepatic, pterygostomial regions ( Figs 21C, D ; 22C, D ), becoming more pronounced in pterygostomial crest, ridge. Posterior margin of epistome ( Figs 21D ; 22D ) sinuous, with median salient tip, lateral margins wide, concave. Distal third to half of fingers dark brown in females ( Fig. 22I, J ), males (21A, I, J). Inner (ventral), distal margin of cheliped carpus ( Figs 21F, D ; 22F ) with long, slender, acute-tipped tooth. P2-P5 long, slender in appearance. Male pleon ( Fig. 21H ) proportionally narrow. G1 ( Fig. 25 Q-S) slender; conspicuously pointed tip; G2 ( Fig. 25T ) slender, nearly equal or slightly longer than G1, slightly curved flagellum, tip with two lateral spinules.

ETYMOLOGY. — From the Latin jugum for ‘yoke’; in reference to the diagnostic yoke-like, wide, and prominently concave lateral margins of the posterior margin of the epistome. Used as a noun in apposition.

COLOUR IN LIFE. — Not known.

GEOGRAPHICAL DISTRIBUTION. — Philippines.

DEPTH. — Present in samples collected at depths of approximately 50-500 m (273-476 m where depths were more accurately measured).

REMARKS

See Remarks for C. polita .

It is noteworthy that most of the specimens of C. jugum n. sp. collected were obtained from tangle nets set on steep deep-sea cliffs, a habitat which is hard to survey (see Ng et al. 2009; Mendoza et al. 2010). This probably explains the paucity of specimens of this species from trawled material in earlier expeditions to Philippines.

Figures

FIG. 21. — Carcinoplax jugum n. sp., holotype ♂ (33.6 × 45.5 mm) (ZRC 2004.0777), Philippines: A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, posterior margin of epistome; E, left third maxilliped; F, dorsal view of carpus of left cheliped; G, dorsal view of carpus of right cheliped; H, thoracic sternum and pleon; I, outer view of right chela; J, outer view of left chela.

FIG. 22. — Carcinoplax jugum n. sp.: A-C, F-J, paratype ♀ (25.1 × 32.5 mm) (ZRC 2006.0217), Philippines; D, E, paratype ♀ (26.9 × 35.4 mm) (ZRC 2018.1431), Philippines: A, overall habitus; B, E, dorsal view of carapace; C, frontal view of cephalothorax; D, posterior margin of epistome; F, dorsal view of carpus of right cheliped; G, thoracic sternum and pleon; H, sternopleonal cavity and vulvae; I, outer view of right chela; J, outer view of left chela.

FIG. 25. — Gonopods: A-E, Carcinoplax specularis Rathbun, 1914, holotype ♂ (16.7 × 23.0 mm) (USNM 46164), Philippines; F-I, C. adelphia n. sp., holotype ♂ (19.4 × 25.4 mm) (MNHN-IU-2016-8002), Vanuatu; J-P, C. fasciata Ng & Kumar, 2016, holotype ♂ (25.8 × 19.3 mm) (DABFUK), India; Q-T, C. jugum n. sp., holotype ♂ (33.6 × 45.5 mm) (ZRC 2004.0777), Philippines. A, right G1 (dorsal view), B, right g1 (ventral view); C, distal part of right G1 (ventral view); D, distal part of right G1 (dorsal view); E, right G2; F, J, Q, left G1 (ventral view); G, K, R, distal part of left G1 (ventral view); H, L, S, distal part of left G1 (dorsal view); I, M, D, Q, left G2; N, right G2; O, P, distal part of right G2. A, after Guinot (1989: fig. 34A). Scale bars: A, B, E, F, I, J, M, N, Q, T, 1.0 mm; C, D, G, H, K, L, R, S, 0.5 mm; O, P, 0.25 mm.