Artopotamon latopeos Chu & Wang & Sun 2018, sp. nov.
Creators: name: Chu, Kelin
name: Wang, Pengfei
name: Sun, Hongying
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Potamidae
Artopotamon
Artopotamon latopeos

description: Artopotamon latopeos sp. nov.
(Figs. 6–9)
Material examined. Holotype, male (adult), 24.5 × 20.5 mm, NNU 170507, Banfang Village (26°17’21’’N 100°27’56’’E, 2075 m asl), Taoyuan Town, Yongsheng County, Dali City, Yunnan Province, coll. Pengfei Wang, Zewei Zhang, Qiang Zhao & Hongying Sun, 5 May 2017. Paratypes: 2 females (adult), 24.7 × 19.8 mm, NNU 170510 (allotype); 24.7 × 19.7 mm, NNU 170503, same data as holotype; 1 male (adult), 25.9 × 21.6 mm, NNU 170502, same data as holotype; 1 male (adult), 25.3 × 20.4 mm, NNU 170521, 1 female (adult), 27.0 × 22.2 mm, NNU 170520, same data as holotype (to be deposited in IZCAS).
Comparative material. Artopotamon compressum Dai & Chen, 1985: holotype, male (23.3 × 18.6 mm), IZCAS CB00733; paratype, male (18.0 × 14.4 mm), IZCAS CB00738; paratype, female (30.6 × 24.0 mm) IZCAS CB00734; all from Lushui County, Yunnan Province, coll. 1981.
Diagnosis. Carapace 1.2 times broader than long, dorsal surface gently convex, surface slightly pitted (Fig. 6A). Third maxilliped exopod reaching proximal 1/3 of merus length, without flagellum (Fig. 7D). Male pleon triangular, lateral margin of pleonal somite 6 slightly convex (Fig. 6C). G1 slender (Fig. 7A, B, E), tip of terminal segment reaching slightly beyond sternal press-button in situ (Fig. 8D), subterminal segment about 1.7 times as long as terminal segment. G1 slightly curved ventrolaterally (Fig. 8D); distal part of terminal segment broader than proximal (Fig. 7A, B, E). Female vulvae on thoracic sternite 6, ovate, opening anteriorly, posterior margin arched distinctly (Fig. 8B, C).
Description. Carapace about 1.2–1.3 times broader than long (n=4), with dorsal surface gently convex, surface slightly pitted; regions distinctly defined (Fig. 6A). Cervical groove shallow, indistinct; H-shaped groove between gastric and cardiac regions shallow but distinct (Fig. 6A). Postfrontal lobe slightly convex, separated medially by Y-shaped groove extending to frontal region; postorbital cristae slightly convex, separated from postfrontal lobe by shallow groove (Fig. 6A); postorbital region distinctly concave (Fig. 6A). Frontal region deflexed downwards, with small granules, anterior border emarginated medially (Fig. 6A, B). Supraorbital margin ridged (Fig. 6A); infraorbital margin slightly cristate (Fig. 6B). Anterior margin of epistome straight, ridged; posterior margin ridged, with granular triangular median lobe (Fig. 6B). External orbital angle sharply triangular, outer margin lined with 3 or 4 small granules (Fig. 6A); epibranchial tooth clearly demarcated from external orbital tooth by gap (Fig. 6A); anterolateral margin gently cristate, lined with round granules (Fig. 6A).
Third maxilliped merus about 1.1–1.3 times as broad as long (n=4), trapezoidal; ischium about 1.4–1.5 times as long as broad (n=4), with distinct median sulcus; exopod reaching proximal third of merus length, without flagellum (Fig. 6B, C, 7D).
Thoracic sternum pitted (Fig. 6C); sternites 1, 2 completely fused to form triangular structure (Fig. 6C); sternites 2, 3 separated by continuous suture (Fig. 6C); boundary between sternites 3, 4 present, indistinct (Fig. 6C). Sterno-pleonal cavity broad, shallow, with narrow median interruption in sutures 4/5, 5/6, 6/7 (Fig. 8D); median line between sternites 7, 8 moderately long (Fig. 8D).
Chelipeds slightly unequal (Fig. 6A); merus trigonal in cross-section, margins crenulated (Fig. 6A); carpus with sharp spine on inner distal angle, with spinule at base (Fig. 6A); outer surface of manus with convex granules, manus about 1.3–1.4 times as long as high (n=4), slightly longer than movable finger, gape narrow when fingers closed, cutting edge lined with low teeth (Fig. 6B, C).
Ambulatory legs slender; dactylus slender, margins with stiff, spine-like setae; margins of propodus serrate (Fig. 6A, C); second ambulatory leg merus about 1.2–1.4 times as long as dactylus (n=4; Fig. 6A); last leg with propodus about 1.7–1.9 times as long as broad, slightly shorter than dactylus (n=4; Fig. 6A).
Male pleon triangular, third somite widest (Fig. 6C); sixth somite width 1.8–2.2 times length (n=4), lateral margins slightly convex; the lateral margin of pleonal somite 6 slightly convex (Fig. 6C); telson width 1.2–1.4 times length, nearly tongue-shaped (n=4; Fig. 6C).
G1 slender, tip of terminal segment slightly reaching beyond sternal press-button in situ (Fig. 8D), subterminal segment about 1.7 times as long as terminal segment (Fig. 7A). G1 slightly curved ventrolaterally (Fig. 8D); distal part of G1 terminal segment distinctly broader than proximal part (Fig. 7A; 10C, D). G2 subterminal segment about 2.3 times as long as terminal segment (Fig. 7F).
Female pleon ovate, surface pitted (Fig. 8A); sixth somite about 2.7 times as broad as long, telson semicircular, about 2.2 times as broad as long (Fig. 8A). Female vulvae on thoracic sternite 6, ovate, opening upward, posterior margin arched distinctly (Fig. 8B, C).
Remarks. The new species fits well within the morphological definition of the hitherto monotypic Artopotamon Dai & Chen, 1985 (type species: A. compressum Dai & Chen, 1985): viz. the third maxilliped exopod is without a flagellum, the lateral margin of pleonal somite 6 is slightly convex (Fig. 6C, 9A), the G1 is generally slender, and female vulvae are on thoracic sternite 6, ovate, and with their posterior margin arched distinctly. Nonetheless, the new species can be distinguished from, Artopotamon compressum Dai & Chen, 1985, by the shallow and indistinct cervical groove (Fig. 6A) (versus wide and distinct in A. compressum (Fig. 9D; cf. Dai, 1999: pl. 343); and the ventrolaterally curved G1, which reaches slightly beyond the sternal press-button, and with the subterminal segment about 1.4 times as long as terminal segment (Fig. 7A) (versus G1 straight, not reaching sternal press-button, subterminal segment about 2.3 times as long as terminal segment in A. compressum; Fig. 7C; cf. Dai, 1999: pl. 343: fig. 186 (3, 4, 5) (also Table 2). By examining the holotype of A. compressum, we found its G1 not reaching the sternal press-button (Fig. 9B), but it is not consistent with the diagnostic characters of Artopotamon as described by Dai & Chen (1985), in which G1 merely reaches the sternal press-button. The most obvious specific character of the new species is that the distal part of the G1 terminal segment is distinctly wider than the proximal part (Fig. 7A), whereas the G1 terminal segment of A. compressum is stick-shaped and uniformly narrow throughout its length (Fig. 7C; cf. Dai, 1999: pl. 343: fig. 186 (3, 4, 5)) (also Table 2). In addition, the new species is found around the Jinsha River valley in Dali and Lijiang City, while A. compressum is recorded only in Pianma Town, Lushui County, Nujiang Lisu Autonomous Prefecture on the Nujiang River basin (Fig. 1). There are distinct geographical barriers between the two localities, such as the Lancang River, Gaoligong Mountains, which most likely contribute to the reproductive isolation of the two species.
Distribution and habitat. Artopotamon latopeos sp. nov. was found around the Jinsha River valley in Dali and Lijiang City. The crabs were found under rocks in mountain streams with an altitude range of 1800–2700 m.
Live coloration. Carapace is generally dark brown to purplish brown in life.
Etymology. The specific epithet, latopeos, is derived from an arbitrary combination of latus (Latin, broad) and peos (Greek, male intromittent organ or penis), in reference to the broader distal part of the G1 terminal segment. It is used here as a noun in apposition.
description: Published as part of Chu, Kelin, Wang, Pengfei & Sun, Hongying, 2018, A new genus and species of primary freshwater crab and a new species of Artopotamon Dai & Chen, 1985 (Crustacea, Brachyura, Potamidae) from western Yunnan, China, pp. 115-131 in Zootaxa 4422 (1) on pages 122-127, DOI: 10.11646/zootaxa.4422.1.7, http://zenodo.org/record/1455529