Indochinamon phongnha, Naruse, Tohru, Quynh, Nguyen Xuan & Yeo, Darren C. J., 2011

Naruse, Tohru, Quynh, Nguyen Xuan & Yeo, Darren C. J., 2011, Three new species of Indochinamon Yeo & Ng, 2007 (Crustacea: Brachyura: Potamoidea: Potamidae) from Vietnam, with a redescription of Ranguna (Ranguna) kimboiensis Dang, 1975, Zootaxa 2732, pp. 33-48 : 41-44

Indochinamon phongnha n. sp.

( Figs. 6 a, b, 7, 8, 9a–c)

Material examined. Holotype: male (68.6 by 51.9 mm) ( ZMHU), Phong Nha National Park, Quang Binh Province, Vietnam, stream near km49 mark of Ho Chi Minh highway, the branch on the west side, elevation 750m, coll. Vu Ngoc Thanh, 22 Jun. 2006.

Paratypes: 1 female (34.9 by 27.5 mm) ( ZMHU), same data as holotype; 5 males (25.4 by 20.2 – 44.2 by 33.2 mm), 6 females (17.9 by 14.1 – 43.0 by 32.6 mm), 1 juvenile (15.4 by 12.5 mm) ( ZRC 2010.0168), Khe Con Khai stream, Cha Noi, Phong Nha, Quang Binh Prov., Vietnam,17˚38.196'N 106˚05.928'E, 263m asl, coll. D. C. J. Yeo & A. D. Tran, 13 Jul. 2004; 2 males (34.3 by 26.6, 31.9 by 24.9 mm), 3 females (38.3 by 29.9 – 54.8 by 41.4 mm), 1 juvenile (17.0 by 13.1 mm) ( ZRC 2010.0169), Cha Noi, Phong Nha, Quang Binh Prov., Vietnam, Stream under bridge, 17˚38.397'N 106˚06.975'E, 261m asl, coll. D. C. J. Yeo & A. D. Tran, 13 Jul. 2004; 3 males (49.0 by 38.3 – 51.3 by 40.1 mm) ( ZMHU), 11 males (16.4 by 13.3 – 64.2 by 48.0 mm), 3 females (32.6 by 25.9 – 38.9 by 30.1 mm) ( ZRC 2010.0170), Vuc Tro stream, Phong Nha, Quang Binh Prov., 17˚38.188'N 106˚12.810'E, coll. D. C. J. Yeo & A. D. Tran, 14 Jul. 2004; 3 females (36.1 by 28.1 – 42.8 by 33.0 mm), 2 juveniles (19.6 by 15.3, 17.3 by 13.6 mm) ( ZRC 2010.0171), Stream near Forest Ranger station 37, Phong Nha, Quang Binh Prov., Vietnam, 17˚31.395'N 106˚17.716'E, 86m asl, coll. D. C. J. Yeo & A. D. Tran, 15 Jul. 2004; 5 males (42.0 by 31.5 – 49.1 by 37.2 mm) ( ZMHU), 3 males (49.8 by 37.8 – 53.0 by 41.5 mm) ( ZRC 2010.0172), Chay stream, Quang Binh Prov., Vietnam, 17˚33.146'N 106˚14.425'E, 94m asl, coll. D. C. J. Yeo & A. D. Tran, 17 Jul. 2004; 1 male (61.9 by 47.3 mm) ( ZRC 2010.0173), Km 23 + 800 HCM Way, near Hang So Dua, Pong Nha National Park, Quang Binh Province, Vietnam, coll. A. D. Tran, 11 Aug. 2001; 1 male (56.9 by 44.0 mm), 1 female (54.2 by 40.8) ( ZRC 2010.0174), Thac Xoi waterfall, Phong Nha National Park, Quang Binh Province, Vietnam, coll. Q. K. Hoang & V. K. Dinl, 10 Aug. 2002.

Diagnosis. Carapace ( Fig. 6 a) oval, CW 1.24–1.34 times (mean 1.30, n = 31) CL, dorsal surface ( Fig. 7 a) flat, regions well defined; epigastric crista distinct, oblique, postorbital crista composed of transverse, short cristae, separated from epigastric crista, externally terminated by cervical groove, cervical groove polygonal line-like, anterolateral region scattered with oblique short granules. Frontal to orbital margins cristate, lined with rounded granules, granules of infraorbital margin ( Fig. 7 a) larger, infraorbital margin interrupted just below external orbital angle by U-shaped notch; suborbital region scattered with granules; subhepatic region covered with short rows of granules. External orbital angle narrow, directed anteriorly, outer margin length about one and a half times inner margin, outer margin cristate, lined with small granules, epibranchial tooth disconnected from outer margin of external orbital angle by short gap of crista, short, not clearly larger than following granules, directed anteriorly; anterolateral margin strongly convex laterally, cristate, regularly lined with large granules, posterolateral margins strongly convergent posteriorly. Posterior margin of epistome ( Fig. 7 a) with one median, long, narrow, sharp lobe, margin besides median lobe composed of elongated granules.

Ischium of third maxilliped broadly rectangular, exopod flagellum longer than half width of merus.

Male cheliped carpus with rugose outer surface, inner angle with sharp, long tooth, followed vento-proximally by one small tooth; male chela ( Fig. 7 b) with swollen palm, scattered with low, rounded granules from outer to lower half of inner surfaces; fingers as long as palm, straight, slightly hook-shaped distally, cutting edge regularly lined with teeth, without gape when closed.

Male abdomen ( Fig. 6 b) tongue-shaped, first segment with distal margin rimmed; second segment with sublateral notch on distal margin, forming rounded lateral lobes; third segment widest; sixth segment longer than telson, telson longer than width.

G1 ( Fig. 8 a, b) with distal third bent outwards; subterminal segment with wide convexity on proximal twofifths of outer margin, distal part of outer margin excavated, connected dorsally to shallow transverse slope; distal segment relatively stout, tip slightly bent proximally in dorsal view, outwards in anterior view, groove for G2 on lateral surface throughout distal segment, elongated opening on distal ventral surface, dorsal flap (protuberance of ventral outer surface) low, slightly visible medially in dorsal view. G2 ( Fig. 8 c) longer than G1, flagellum curving outwards, J-shaped.

Live colouration. The dorsal carapace and chelipeds, and ambulatory legs, are mostly brownish-grey. The upper half of the third maxillipeds (from the palp to the upper part of the ischium) and the suborbital, pterygostomial, subhepatic, and subbranchial regions are a lighter more orange shade. The anterolateral and external orbital angle margins, orbital and frontal margins, and the posterior margin of the epistome are bright orange in colour. The distal parts of the fingers of the chelae are bright orange with the tips being white, the orange colour spreading to the lower half and cutting edge of the movable finger and to most of the fixed finger ( Fig. 6 a, b).

Habitat and distribution. The species inhabits slow to fast flowing, forest streams with various combinations of rock, sandy, and mud substrata, and patches of leaf litter, in the Phong Nha-Ke Bang National Park, Quang Binh Province of northern-central Vietnam.

Etymology. The new species is named after the type locality, Phong Nha National Park. The name is used as noun in apposition.

Remarks. Indochinamon phongnha n. sp. can be distinguished from I. kimboiense by the characters of the carapace and the G1. In I. phongnha n. sp., the anterolateral margins of the carapace are more produced ( Fig. 6 a), the dorsal surface of the carapace is lower ( Fig. 7 a), the G1 is more strongly bent laterally at distal part of the subterminal segment ( Fig. 8 a, b), and the dorsal flap of the distal segment of the G1 is low but proportionately longer ( Fig. 8 a, b). In contrast, in I. kimboiense , the anterolateral margins of the carapace are less produced ( Fig. 1 a), the dorsal surface of the carapace is slightly convex ( Fig. 2 a), the G1 is less strongly bent laterally at distal part of the subterminal segment ( Fig. 3 a, b), and the dorsal flap of the distal segment of the G1 is slightly higher but shorter than that of I. phongnha n. sp. ( Fig. 3 a, b).

Figures

FIGURE 1. Indochinamon kimboiense (Dang, 1975). Neotype (ZMHU, male, CL 63.5 mm, CW 80.7 mm). a, dorsal view; b, ventral view.

FIGURE 2. Indochinamon kimboiense (Dang, 1975). Neotype (ZMHU, male, CL 63.5 mm, CW 80.7 mm). a, frontal view; b, major chela.

FIGURE 3. Male G 1 and G 2 of Indochinamon kimboiense (Dang, 1975) and I. bavi n. sp. a, d, right G 1, ventral view; b, e, right G 1, dorsal view; c, f, left G 2, ventral view. a – c, I. kimboiense, neotype (ZMHU, male, CL 63.5 mm, CW 80.7 mm); d – f, I. bavi, holotype (ZMHU, male, CL 42.9 mm, CW 56.8 mm). Scales = 5 mm.

FIGURE 6. Live colourations of Indochinamon species. a, b, I. phongnha n. sp.; c, d, I. dangi n. sp.; e, f, I. bavi n. sp.

FIGURE 7. Indochinamon phongnha n. sp. Holotype (ZMHU, male, CL 51.9 mm, CW 68.6 mm). a, dorsal view; b, ventral view.

FIGURE 8. Indochinamon phongnha n. sp. Holotype (ZMHU, male, CL 51.9 mm, CW 68.6 mm). a, frontal view; b, major chela.