Chinommatia turpis, Ng, Peter K. L. & Castro, Peter, 2016

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 70-71

Chinommatia turpis n. sp.

( Fig. 15 E, F; 25F; 32E; 43I, J; 53E; 60D; 76A‒E)

Type material. Holotype male (3.1 × 4.3 mm) (MNHN-IU-2013-9044), Vanuatu, Espiritu Santo I., Big Bay , MUSORSTOM 8, stn DW1115, 15°10’S, 166°53'E, 147–150 m, 0 9.10.1994.

Diagnosis. Carapace ( Fig. 15 E, F) of holotype male subovate, convex, 1.4 wider than long; front bilobed, with shallow median cleft; anterolateral margins arcuate, row of conspicuous, elevated tubercles (17 on right side) along each margin; thick, short tomentum on dorsal, lateral surfaces of carapace. Eye peduncle ( Fig. 25 F) filling orbit, short, thick, mobile; cornea large, not reduced, pigmented. Epistome ( Fig. 25 F) with semicircular median lobe with deep median fissure, semicircular lateral margins. Third maxilliped ( Fig. 32 E) merus ovate, anteroexternal angle rounded; ischium rectangular, slightly longer than merus. Proportionally short ambulatory legs ( Fig. 15 E), with conspicuous tomentum; P5 merus 0.5 cl. Chelipeds ( Figs. 15 E; 43I, J) subequal in length, heteromorphic; fingers of minor chela ( Fig. 43 J) subcircular in cross-section, scissor-like, cutting margins with few short teeth; large teeth on cutting margin of major chela of males ( Fig. 43 I). Inner margin of cheliped carpus with short tooth. Ventral surface of cheliped merus with row of tubercles on inner margin. Inner margin of cheliped carpus with short tooth ( Fig. 15 E). Fused thoracic sternites 1, 2 ( Fig. 53 E) semicircular, broad, long. Male pleon ( Figs. 53 E; 60D) with proportionally long telson. G1 ( Fig. 76 A‒C) slender, distal segment slightly straight, tapered, with short spinules. G2 ( Fig. 76 D, E) about 1/3 G1 length, straight, short distal segment. Female unknown.

Etymology. The epithet turpis is from the Latin for “filthy” and “dirty” alluding to the appearance of the species in life. The name is used as a noun in apposition.

Remarks. Despite the small size of the holotype, it is already fully mature with the gonopods fully developed. In size and general features, C. turpis n. sp. most closely resembles C. littoralis ( Tesch, 1918) by the form of the anterolateral margin; being lined with small granules in C. littoralis ( Fig. 15 A) but covered with larger, uneven ones in C. turpis n. sp. ( Fig. 15 E, F). In addition, the ocular peduncle of C. turpis n. sp. ( Fig. 25 F) is proportionately shorter than C. littoralis ( Fig. 25 E); and the merus of the third maxilliped is relatively wider and more quadrate in C. turpis n. sp. ( Fig. 32 E) compared to that in C. littoralis ( Fig. 32 C). Since C. littoralis is only known from a female specimen from Indonesia, comparisons of the male characters are not possible.

Chinommatia turpis n. sp. is unusual among Chinommatia species in that it is not only the most pilose member of the genus, it also has proportionately the shortest eye. In addition, the G1 structure of C. turpis n. sp. is relatively more slender, especially along its distal half, than congeners, and the G2 is relatively shorter. In the characters of the eye, G1, and G2, C. turpis n. sp. more closely resembles species of Statommatia n. gen. Chinommatia turpis n. sp. nevertheless possesses a key diagnostic character for Chinommatia : the eye is mobile. The eye is fused to the cephalothorax in Statommatia n. gen. species. The status of C. turpis n. sp. should be reappraised when more material (including females) becomes available.

Distribution. Known only from Vanuatu. Depth: 147– 150 m.

Figures

FIGURE 15. Overall dorsal view of species of Chinommatia n. gen. and Notopelta n. gen. A, Chinommatia littoralis, Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); B, Chinommatia bicuspida n. sp., Papua New Guinea: holotype male 10.7 × 12.9 mm (MNHN-IU- 2011 - 0954); C, Chinommatia bicuspida n. sp., Fiji: male 12.7 × 10.6 mm (MNHN-IU- 2013 - 9056); D, Chinommatia bicuspida n. sp., Papua New Guinea: paratype female 16.7 × 20.4 mm (MNHN-IU- 2011 - 3461); E, F, Chinommatia turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044); G, H, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397); I, Notopelta mortenseni, Indonesia: female 5.9 × 4.1 mm (ZMUC CRU- 007768).

FIGURE 25. Frontal view of species of Chinommatia n. gen. and Notopelta n. gen. A, Chinommatia cavimanus, Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); B, Chinommatia bicuspida n. sp., Papua New Guinea: paratype female 16.7 × 20.4 mm (MNHN-IU- 2011 - 3461); C, Chinommatia bruuni, Java Sea: male 3.4 × 4.0 mm (ZMUC CRU- 1524); D, Chinommatia bruuni, Malaysia: female 5.5 × 7.2 mm (ZRC 2013.0020), Malaysia; E, Chinommatia littoralis, Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); F, Chinommatia turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044); G, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397).

FIGURE 32. Third maxilliped of species of Chinommatia n. gen. A, C. cavimanus, Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); B, C. bruuni, Indonesia: male 3.4 × 4.0 mm (ZMUC CRU- 1524); C, C. littoralis, Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); D, C. bicuspida n. sp., Papua New Guinea: paratype female 16.7 × 20.4 mm (MNHN-IU- 2011 - 3461); E, C. turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044); F, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397). Scale = 0.5 mm.

FIGURE 43. Chelae of species of Chinommatia n. gen. A, B, C. cavimanus, Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); C, D, C. bruuni, Indonesia: 1 male 3.4 × 4.0 mm (ZMUC CRU- 1524); E, F, C. bicuspida n. sp., Fiji: male 12.7 × 10.6 mm (MNHN-IU- 2013 - 9056); G, C. bicuspida n. sp., Papua New Guinea: holotype male 10.7 × 12.9 mm (MNHN-IU- 2011 - 0954); H, C. littoralis, Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); I, J, C. turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044).

FIGURE 53. Anterior thoracic sternum and male pleon of species of Chinommatia n. gen. and Notopelta n. gen. A, Chinommatia cavimanus, holotype male 11.4 × 13.9 mm (USNM 46413); B, Chinommatia cavimanus, Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); C, Chinommatia bruuni, Indonesia: male 3.4 × 4.0 mm (ZMUC CRU- 1524); D, Chinommatia bicuspida n. sp., Papua New Guinea: holotype male 10.7 × 12.9 mm (MNHN-IU- 2011 - 0954); E, Chinommatia turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044); F, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397).

FIGURE 76. Gonopods of species of Chinommatia n. gen. and Notopelta n. gen. A ‒ E, Chinommatia turpis n. sp., Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU- 2013 - 9044); F ‒ I, Notopelta mortenseni, Sunda Strait: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397). A, F, ventral view of left G 1; B, G, ventral view of distal part of left G 1; C, H, dorsal view of distal part of left G 1; D, left G 2 (tip damaged); I, left G 2; E, right G 2. Scales: F – I = 0.5 mm; A ‒ H = 0.1 mm.