Carcinoplax polita Guinot 1989
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Goneplacidae
Carcinoplax
Carcinoplax polita

description: Carcinoplax polita Guinot, 1989
(Figs 16 A-H; 17 A-I; 24 I-O; 27 G, H)
Carcinoplax polita Guinot, 1989: 298, figs 24, 37, pl. 8, figs E-H [type locality: southern Luzon, Philippines]. — Ng et al. 2008: 80 [in list].
Carcinoplax specularis [part] – Castro 2007: 640 [Taiwan, Philippines].
TYPE MATERIAL. — Holotype. South China Sea • ♂, 14.5 × 20.4 mm; MUSORSTOM 1, stn CP31; MNHN-IU-2008-10565 (= MNHN- B10140); allotype ♀, 12.5 × 16.9 mm; MNHN-IU-2008-10584 (= MNHN-B10543); paratype ♂, 9.2 × 12.2 mm; MNHN- IU-2008-10571 (= MNHN-B10268).
TYPE LOCALITY. — South China Sea, Philippines, southern Luzon, 187- 195 m.
MATERIAL EXAMINED. — South China Sea • 1 ♀, 8.8 × 12.7 mm; NANHAI 2014, stn CP4116; 20°02.3211’N, 114°10.2157’E; 262-298 m depth; 11.I.2014; ZRC 2018.1428 • 1 ♀, 9.8 × 13.9 mm; DONGSHA 2014, stn CP4128, Dongsha Is, 20°44.857’N, 116°08.01’E; 420-444 m depth; 1.V.2014; ZRC 2018.1429.
Philippines • 1 ♀, 8.7 × 12.4 mm; Bohol, Balicasag I., off Panglao I.; tangle nets of local fishermen; 9°31’00.2”N, 123°40’50.5”E; 2-700 m depth;. XII.2000; ZRC 2019.0565 • 2 ♂, 13.6 × 18.9 mm, 15.0 × 19.4 mm; same location as ZRC 2019.0565; 200-300 m depth;. I.2004; ZRC 2004.0805 • 1 ♂, 25-30; same location as ZRC 2019.0565;. VII.2006; ZRC 2019.0567 ex ZRC 2004.0730 (part) • 4 ♀, 11.6 ×15.6 to 16.0 × 22.4 mm, 5 ♂, 14.1 × 20.0 mm to 15.0 × 20.9 mm; same location as ZRC 2019.0565; 50-500 m depth; 2.III.2004; ZRC 2004.0727 • 1 ovigerous ♀, 15.4 × 21.4 mm, 1 ♀, 5 ♂, largest 17.8 × 24.5 mm; same location as ZRC 2019.0565; 50-500 m depth; 28.XI.2001; ZRC 2001.0540 • 1 ♀, 2 ♂; same location as ZRC 2019.0565; 50-500 m depth; 25-30 July. 2006; ZRC 2019.0566, ex ZRC 2001.0845 (part) • 2 ♀, 2 ♂; same location as ZRC 2019.0565; coll. M. Takeda & H. Komatsu, II.2003; NSMT-Cr 15365 • 1 ♀, 12.8 × 17.8 mm; PANGLAO 2004, stn P1, tangle nets of local fishermen; 09°36’S, 123°45’E, 90-200 m depth; ZRC 2006.017 • 1 ♂, 14.5 × 20.0 mm; PANGLAO 2004, stn P4, 09°31’00.2”N, 123°40’50.5”E, tangle nets of local fishermen; 8.VI.2004; ZRC 2006.0173 • 1 ♂, 25.9 × 30.1 mm; AURORA 2007, stn CP2709, Luzon Sea; 15°11.07’N, 121°34.72’E - 15°12.36’N, 121°34.02’E; 244-296 m depth; 28.V.2007; ZRC 2019.0545.
Indonesia. 1 ♂, 6.5 × 7.9 mm; SJADES, stn CP34, E. Indian Ocean; 07°44.464’S, 107°39.018’E; 234-243 m depth; 29.III.2018; ZRC 2018.1417.
DIAGNOSIS. — Carapace (Figs 16A, B; 17A, B, E; 27G, H) quadrate, slightly wider than long (1.4 × wider than long in holotype); slightly convex, marked by two distinct transverse elevations across cardiac, gastric regions. Front (Figs 16H; 17B, C, F) straight, no notch between front, inner edge of supraorbital border (slight notch in some specimens). Rounded, short tooth on outer orbital angle; margin between outer orbital tooth, anterolateral teeth distinctly granular; two slender, acute-tipped anterolateral teeth on each side of carapace, second tooth curved. Large, high granules on subhepatic, pterygostomial regions (Figs 16C; 17B, C, F), particularly pronounced in pterygostomial crest, ridge; short granules on anterior (sometimes throughout) dorsal surface of carapace. Posterior margin of epistome (Fig. 17B, C, F) straight, notch on each lateral margin absent or slight. Distal fourth of fingers dark brown in females (Fig. 17D, I), males (Fig. 16A, H). “Window” not observed on cheliped propodi. Inner (ventral), distal margin of cheliped carpus (Fig. 16E, F) with acute, curved, triangular tooth typically accompanied by tooth-like tubercles along margin of carpus; outer, proximal margin with short tooth. P2-P5 (Figs 16A; 17D; 27G, H) moderately stout in appearance, P5 barely reaching tip of second anterolateral tooth. Male pleon proportionally narrow (Fig. 16G). G1 (Fig. 24I, K, L-N; Guinot 1989: fig. 37A) slender, subconical, with tapering tip, sometimes elongated; scattered spinules; G2 (Fig. 24J, O; Guinot 1989: fig. 37B) slender, nearly equal or slightly longer than G1, straight flagellum, tip with two lateral spinules.
COLOUR IN LIFE. — Colours of the two photographed individuals (Fig. 27G, H) varies from orange to bright red-orange. Legs (P2-P5) are orange to red-orange with white proximal and distal portions.
GEOGRAPHICAL DISTRIBUTION. — Taiwan, South China Sea, Philippines, and Indonesia (southern Java).
DEPTH. — Present in samples collected at depths of 200- 700 m.
REMARKS
The carapaces of two species (C. polita and C. jugum n. sp.) are distinctive in that the gastric and cardiac regions are distinctively more swollen laterally, so much so that the dorsal surface appears gently corrugated, with a shallow but distinct transverse furrow between the regions (Figs 16A, B; 17A, B, E; 27G, H). This is particularly obvious when the surface is dried. While there is also a shallow groove between the gastric and cardiac regions in the other species, the conditions in C. polita and C. jugum n. sp. are unusual in that the groove is distinctly wider and more prominent. The chelipeds of these two species are also distinctive in that only the distal third or half of the fingers are pigmented, even in juveniles. Carcinoplax polita is a very distinctive taxon in that it is the only member of this group of species that has an additional spine on the outer surface of the carpus of the cheliped (Fig. 16E). All other species, including C. jugum n. sp., has a smooth and unarmed outer margin. The spine is always present, even if eroded, and occurs even in small specimens and females. In addition to the structure of the cheliped carpal spines, C. polita is easily separated from C. jugum n. sp. in that the margins between the outer orbital tooth and the anterolateral teeth are distinctly granular (Fig. 17F) (margins appear smooth in C. jugum n. sp.; Fig. 21C); the dorsal surface of the carapace is gently convex in frontal view (Figs 16C; 17B, F) (more prominently inflated in C. jugum n. sp.; Figs 21C; 22C); the posterior margin of the epistome with a prominent triangular median lobe and strongly concave lateral margins (Fig. 17B, C, F) (median lobe more obtuse, lower and the lateral margins distinctively v-shaped in C. jugum n. sp.; Figs 21D; 22D); possessing a proportionally wider male pleon (Fig. 16G) than in C. jugum n. sp. (Fig. 21H), and most significantly, the G1 has the distal part subconical in form with the tip tapering, sometimes elongated, and directed obliquely laterally (Fig. 24I, K, L-N) (the distal part is more dilated, resembling a bird’s head with the tip never elongated and directed upwards in C. jugum n. sp.; Fig. 25 Q-S).
Small but adult specimens of C. polita (15-18 mm CL), including the holotype, have a G1 which is gently sinuous, with the distal part subconical in form and the tip tapering but short (Fig. 24I, K). In a very large specimen of C. polita (25.9 × 30.1 mm, ZRC 2019.0545), the overall G1 is proportionately more slender than in smaller specimens, with the tip of the distal part prominently more elongated (Fig. 24 L- N). This specimen, however, agrees in all other aspects with typical C. polita, although that it has relatively larger granules on the carapace surface. These differences are likely to be associated with its large size.
description: Published as part of 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), pp. 239-284 in Zoosystema 42 (17) on pages 265-268, DOI: 10.5252/zoosystema2020v42a17, http://zenodo.org/record/3894945