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) Ng, Peter K. L. Castro, Peter Zoosystema 2020 2020-06-09 42 17 239 284 84GR4 Ng & Castro, 2020 Ng & Castro 2020 [985,1217,1109,1136] Malacostraca Goneplacidae Carcinoplax Animalia Decapoda 31 268 Arthropoda species adelphia sp. nov.  ( Figs 19A-H; 20A-I; 25F-I; 27E, F)  urn:lsid:zoobank.org:act: 4AA2E938-5F47-4B42-8BCC-83A2CD1D8E18  TYPE MATERIAL. —   Holotype.  Vanuatu• ♂, 19.4 × 25.4 mm; Vanuatu; MNHN-IU-2016-8002.    Paratypes.  Vanuatu• 2 ♀, largest 16.9 × 22.4 mm; SANTO 2006, stn AT19, S. UrelapaI.; 15°41’S, 167°01’E;  503-600 mdepth;  21.IX.2006, ZRC 2009.0997• 1 ovigerous ♀, 14.4 × 19.0 mm; SANTO 2006, stn AT96, Big Bay, Santo; 15°06.9’S, 166°52.8’E;  328-354 mdepth;  14.X.2006; ZRC 2018.1412•  1 ♀, 16.9 × 22.4 mm, 1 ♂, 15.7 × 21.2 mm; SANTO 2006, stn AT98, Big Bay; 15°06.6’S, 166°50.6’E;  347-394 mdepth;  14.X.2006; ZRC 2009.0922•  5 ♀, 16.5 × 22.5 mm, 2 ♂, larger one cl 12.3 mm, damaged; same data as ZRC 2009.0922; ZRC 2009.0998•  1 ♂, 18.8 × 29.9 mm; SANTO 2006, stn AT99, Big Bay; 15°05.5’S, 166°50.9’E;  351-395 mdepth;  14.X.2006; ZRC 2008.0907•  10 ♀, largest 13.6 × 18.3 mm, 15.9 × 20.8 mm, 1 ♂, 16.0 × 22.9 mm; same data as ZRC 2008.0907; ZRC 2009.0996• 1 ovigerous ♀, 17.7 × 24.2 mm; same data as ZRC 2008.0907; ZRC 2018.1413•  3 ♀, largest 15.1 × 19.3 mm, 14 ♂; SANTO 2006, stn AT100, Big Bay; 15°06.0’S, 166°51.4’E;  399-416 mdepth;  14.X.2006; MNHN-IU-2016-8002• 1 ovi- gerous ♀, 8.5 × 11.2 mm, 1 ♂, 7.6 × 11.2 mm; SANTO 2006, stn AT121, W MaloI.; 15°38.7’S, 167°01.2’E;  275-290 mdepth;  19.X.2006, ZRC 2009.0989• 1 ♂, trap 3, no other data, MNHN-IU-2010-5546.  TYPE LOCALITY. — Vanuatu, SANTO 2006; stn AT100, Big Bay; 15°06.0’S, 166°51.4’E; 399-416 mdepth.  DIAGNOSIS. — Carapace ( Figs 19A, B; 20A, B; 27E, F) quadrate, slightly wider than long (1.4 × wider than long in holotype); slightly convex, smooth. Front ( Figs 19C, D; 20C, D) straight, slight notch between front, inner edge of supraorbital border. Rounded, short tooth on outer orbital angle; two slender, acutetipped anterolateral teeth on each side of carapace. Conspicuous granules on subhepatic, pterygostomial regions ( Figs 19C, D; 20C, D), becoming more pronounced in pterygostomial crest, ridge; short granules on anterior, dorsal surface of carapace. Posterior margin of epistome ( Figs 19D; 20D) straight, slight notch on each lateral margin. Distal 2/3 to half of fingers dark brown in females ( Fig. 20A, F, I), males ( Fig. 19A, F, H). Smooth, oblong “window” on inner, dorsal surface of cheliped propodi of some males ( Fig. 19F). Inner (ventral), distal margin of cheliped carpus ( Figs 19F; 20F) with triangular tooth. P2-P5 ( Figs 19A; 20A; 27E, F) moderately stout in appearance, P5 not reaching second anterolateral tooth. Malepleon ( Fig. 19G) proportionally narrow. G1 ( Fig. 25F-H) slender; pointed tip with scattered spinules; G2 ( Fig. 25I) slender, nearly equal or slightly longer than G1, slightly curved flagellum, tip with two lateral spinules.  ETYMOLOGY. — The name is derived from the Greek adelphosfor ‘brother’ or ‘sister,’ alluding to the close affinities of the new species with  C. specularis. The name is treated as a noun. COLOUR IN LIFE. — Orange with a semi-circular row of small white spots on each side of the carapace ( Fig. 27E, F).  GEOGRAPHICAL DISTRIBUTION. — Vanuatu. DEPTH. — Present in samples collected at depths of 275- 600 m.  REMARKS   Carcinoplax adelphia n. sp.and  C. specularisare superficially very similar, including the spots on the dorsal surface of the carapace shown in life ( Fig. 27E, Ffor  C. adelphia n. sp.; Fig. 27Dfor  C. specularis). They are, however, easily separated by the structure of their G1s. The G1 is relatively shorter and stouter in  C. specularis( Fig. 25A, B,) than in  C. adelphia n. sp., which is more elongated, particularly the distinctly more slender distal half ( Fig. 25F).   Carcinoplax speculariscan be also separated from allied species by the obtusely triangular median part of the posterior margin of its epistome, which extends beyond the lateral margins, with the lateral margins gently concave ( Figs 10D; 11D; 12D) (median part very low and almost at the same level as the lateral margins, which are almost straight in  C. adelphia n. sp.; Figs 19D; 20D). Both share a similar colour pattern, with two unique semi-circular rows of white spots on the dorsal surface of the carapace of live individuals ( Fig. 27Dfor  C. specularis; Fig. 27E, Ffor  C. adelphia n. sp.). Like in C. specularis, a “window” on the chela was found in a few large males of  C. adelphia n. sp.: 15.7 × 21.2 mm(ZRC 2009.0922), 18.8 × 29.9 mm(ZRC 2008.0907) and the holotype19.4 × 25.4 mm(MNHN-IU-2016-8002). These are not obvious in females or juveniles. 2636192430 Vanuatu Vanuatu 31 268 2 1 holotype 2636192338 2006-09-21 ZRC Vanuatu 552 -15.683333 Urelapa 1284 167.01666 31 268 ZRC 2009.0997 2 2 paratype 2636192355 2006-10-14 ZRC Vanuatu 341 -15.115 Big Bay 128 166.88 Santo 31 268 ZRC 2018.1412 1 1 paratype 2636192422 2006-10-14 ZRC Vanuatu 371 -15.11 Big Bay 128 166.84334 31 268 ZRC 2009.0922 2 1 1 paratype 2636192396 2006-10-14 ZRC Vanuatu 371 -15.11 Big Bay 128 166.84334 31 268 ZRC 2009.0998 7 5 2 paratype 2636192392 2006-10-14 ZRC Vanuatu 373 -15.091666 Big Bay 128 166.84833 31 268 ZRC 2008.0907 1 1 paratype 2636192322 2006-10-14 ZRC Vanuatu 373 -15.091666 Big Bay 128 166.84833 31 268 ZRC 2009.0996 11 10 1 paratype 2636192313 2006-10-14 ZRC Vanuatu 373 -15.091666 Big Bay 128 166.84833 31 268 ZRC 2018.1413 1 1 paratype 2636192451 2006-10-14 Vanuatu 408 -15.1 Big Bay 128 166.85667 31 268 17 3 14 paratype 2636192381 2006-10-19 ZRC Vanuatu 283 -15.645 Malo 128 167.02 31 268 ZRC 2009.0989 2 1 1 paratype