Angustopelta cribrorum ( Rathbun, 1932 ) Rathbun, 1932

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 57-59

publication ID	https://doi.org/ 10.11646/zootaxa.4209.1.1
publication LSID	lsid:zoobank.org:pub:849BAB5C-464A-4B4A-A586-5742411EDC01
DOI	https://doi.org/10.5281/zenodo.5617137
persistent identifier	https://treatment.plazi.org/id/F16BFB33-FF9B-FFC1-FF6A-F98DFBA2FCC6
treatment provided by	Plazi
scientific name	Angustopelta cribrorum ( Rathbun, 1932 )
status	comb. nov.

Treatment

Angustopelta cribrorum ( Rathbun, 1932) View in CoL n. comb.

( Figs. 11 View FIGURE 11 D–F; 24E; 31F; 41C‒F; 52E, F; 59E, I; 73F‒I; 101E)

Hephthopelta cribrorum Rathbun, 1932: 35 View in CoL [type locality: Japan, Sagami Bay].— Sakai 1939: 575; 1976: 551, fig. 298 [Japan].—Ng et al. 2008: 76 [in list].

Hephthopelta criborum [sic]— Serène 1964a: 240 [in list], 241, 242 [in key]; 1968: 92 [in list].

Type material. Holotype male (13.6 × 14.9 mm) ( USNM 46388 View Materials ), Japan, Sagami Bay , 14 mi. off Joka Shima Light, Albatross, stn 5086, 35°08’15”N, 139°22’E, 534 m, green mud, coarse black sand, 23.10.1906. GoogleMaps

Other material examined. South China Sea. 1 male (9.9 × 11.6 mm) ( ZRC 2015.214 View Materials ), off Pratas Is., stn CP4130, 20°17.971’N –15.914’N to 116°07.966’E– 116°07.987’E, 795–822 m, T.- Y. Chan coll., 02.05.2014; 1 female (10.8 × 12.5 mm) ( ZRC 2015.296 View Materials ), southwest off Tungsha Islands , stn. CP4133 , 20°04.51’N– 19°58.89’N to 116°22.367’E–116°24.28’E, 999–1070 m, sandy bottom with thin-stalked sponges, Zhongsha Expedition, T.-Y. Chan coll., 22.07.2015.

Diagnosis. Carapace ( Figs. 11 View FIGURE 11 D–F; 101E) subtrapezoidal, gently convex, front bilobed, with shallow median cleft; anterolateral margins arcuate, minutely granular with granules higher along lateral margins, without distinct large tubercles or teeth. Eye peduncle ( Fig. 24 View FIGURE 24 E) filling orbit, short, immobile; cornea reduced, with reduced pigmentation. Epistome ( Fig. 24 View FIGURE 24 E) broad, posterior margin with semicircular median lobe with deep median fissure, semicircular lateral margins. Third maxilliped ( Fig. 31 View FIGURE 31 F) merus subquadrate, ischium quadrate, slightly longer than merus. Proportionally long ambulatory legs ( Fig. 11 View FIGURE 11 D, E), folded P5 reaching front. Chelipeds ( Figs. 11 View FIGURE 11 E, F; 41C–F; 101E) subequal in length, heteromorphic; fingers of minor chela ( Fig. 41 View FIGURE 41 D, F) subcircular in crosssection, gently tapering to tip, scissor-like, cutting margins with distinct sharp teeth; closed fingers of major chela of males forming wide, circular gap. Inner margin of cheliped carpus with sharp tooth. Ventral surface of cheliped merus with 4 teeth along outer margin, large median tubercle on distal margin in holotype. Inner margin of carpi with long distal tooth ( Fig. 11 View FIGURE 11 D, E). Fused thoracic sternites 1, 2 ( Fig. 52 View FIGURE 52 E, F) semicircular, transversely narrow, long. Press-button for pleonal holding as small, short tubercle posterior to thoracic sternal suture 4/5 near edge of sterno-pleonal cavity ( Fig. 59 View FIGURE 59 I). Male pleon ( Figs. 52 View FIGURE 52 E, F; 59E) with proportionally short telson. G1 ( Fig. 73 View FIGURE 73 F‒H) stout, distal segment curved outwards, with short spinules, tuft of setae just before tip. G2 ( Fig. 73 View FIGURE 73 I) about 1/2 G1 length, straight, distal segment proportionally long. Female unknown.

Colour. The carapace and pereiopods are dirty white when cleaned in freshly collected specimens ( Fig. 101 View FIGURE 101 E).

Remarks. The illustration of the supposed USNM holotype given by Sakai (1976: fig. 298) is very schematic and does not correspond to the actual specimen (USNM 46388; Fig. 11 View FIGURE 11 D). The front is rounded, not straight, and the carapace is nearly oval, not subtrapezoidal in the illustration. The only remaining cheliped, the left one, is drawn more accurately. The holotype is diagnosed in detail with ample figures here. Recent Taiwanese specimens collected from off Pratas Is. in the northern South China Sea agree very well with the type and we are confident they are conspecific.

Angustopelta cribrorum has a carapace that is very similar to A. robusta n. sp. and A. modesta n. sp., being subtrapezoidal and with the anterolateral margin entire or with only a small tubercle. In the case of A. cribrorum , no granule or tubercle is visible on the anterolateral margin at all in both specimens, although the margin appears to be uneven ( Fig. 11 View FIGURE 11 D‒F). While usually visible as a small tubercle in A. robusta n. sp. and A. modesta n. sp. (e.g., Fig. 13 View FIGURE 13 F, H), however, it is also sometimes absent in these two species (e.g., Fig. 13 View FIGURE 13 A, G) so this cannot be a good character. Compared to A. robusta n. sp., A. cribrorum has proportionately longer and more slender ambulatory legs ( Fig. 11 View FIGURE 11 D, E) (shorter and stouter in A. robusta n. sp.; Fig. 12 View FIGURE 12 A, B); the lateral margins of male pleonites 3 and 4 are more rounded and convex ( Fig. 59 View FIGURE 59 E) (somites more acute and less convex in A. robusta n. sp.; Fig. 59 View FIGURE 59 F); and most significantly, the basal part of the G1 is more truncate and the distal part is relatively more slender ( Fig. 73 View FIGURE 73 F‒H) (G1 with basal part less truncate and the distal part is relatively stouter in A. robusta n. sp.; Fig. 74 View FIGURE 74 A‒D). The ambulatory legs of A. modesta n. sp. ( Fig. 12 View FIGURE 12 C‒G) are comparable to those of A. cribrorum ( Fig. 11 View FIGURE 11 D, E), but the sutures between male pleonites 3‒5 are still visible ( Fig. 59 View FIGURE 59 G, H) (absent in A. cribrorum ; Fig. 59 View FIGURE 59 E), and the basal part of the G1 is relatively more slender, with the distal part longer, more slender and distinctly curved ( Fig. 74 View FIGURE 74 F‒H) (G1 with basal part stouter and distal part shorter, stouter and gently curved in A. cribrorum ; Fig. 73 View FIGURE 73 F‒H).