Artopotamon latopeos, Chu & Wang & Sun, 2018

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, Zootaxa 4422 (1), pp. 115-131 : 122-127

publication ID	https://doi.org/ 10.11646/zootaxa.4422.1.7
publication LSID	lsid:zoobank.org:pub:FD189628-926E-4FA1-9A6F-74B47453D74C
DOI	https://doi.org/10.5281/zenodo.5967523
persistent identifier	https://treatment.plazi.org/id/232387B9-7F49-F84D-FF52-FB461D7D56D6
treatment provided by	Plazi
scientific name	Artopotamon latopeos
status	sp. nov.

Treatment

Artopotamon latopeos View in CoL sp. nov.

( Figs. 6–9 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 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 GoogleMaps , 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 GoogleMaps ; 1 male (adult), 25.9 × 21.6 mm, NNU 170502, same data as holotype GoogleMaps ; 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) GoogleMaps .

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 View Materials ; 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 View FIGURE 6 ). Third maxilliped exopod reaching proximal 1/3 of merus length, without flagellum ( Fig. 7D View FIGURE 7 ). Male pleon triangular, lateral margin of pleonal somite 6 slightly convex ( Fig. 6C View FIGURE 6 ). G1 slender ( Fig. 7A, B, E View FIGURE 7 ), tip of terminal segment reaching slightly beyond sternal press-button in situ ( Fig. 8D View FIGURE 8 ), subterminal segment about 1.7 times as long as terminal segment. G1 slightly curved ventrolaterally ( Fig. 8D View FIGURE 8 ); distal part of terminal segment broader than proximal ( Fig. 7A, B, E View FIGURE 7 ). Female vulvae on thoracic sternite 6, ovate, opening anteriorly, posterior margin arched distinctly ( Fig. 8B, C View FIGURE 8 ).

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 View FIGURE 6 ). Cervical groove shallow, indistinct; H-shaped groove between gastric and cardiac regions shallow but distinct ( Fig. 6A View FIGURE 6 ). 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 View FIGURE 6 ); postorbital region distinctly concave ( Fig. 6A View FIGURE 6 ). Frontal region deflexed downwards, with small granules, anterior border emarginated medially ( Fig. 6A, B View FIGURE 6 ). Supraorbital margin ridged ( Fig. 6A View FIGURE 6 ); infraorbital margin slightly cristate ( Fig. 6B View FIGURE 6 ). Anterior margin of epistome straight, ridged; posterior margin ridged, with granular triangular median lobe ( Fig. 6B View FIGURE 6 ). External orbital angle sharply triangular, outer margin lined with 3 or 4 small granules ( Fig. 6A View FIGURE 6 ); epibranchial tooth clearly demarcated from external orbital tooth by gap ( Fig. 6A View FIGURE 6 ); anterolateral margin gently cristate, lined with round granules ( Fig. 6A View FIGURE 6 ).

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 View FIGURE 6 , 7D View FIGURE 7 ).

Thoracic sternum pitted ( Fig. 6C View FIGURE 6 ); sternites 1, 2 completely fused to form triangular structure ( Fig. 6C View FIGURE 6 ); sternites 2, 3 separated by continuous suture ( Fig. 6C View FIGURE 6 ); boundary between sternites 3, 4 present, indistinct ( Fig. 6C View FIGURE 6 ). Sterno-pleonal cavity broad, shallow, with narrow median interruption in sutures 4/5, 5/6, 6/7 ( Fig. 8D View FIGURE 8 ); median line between sternites 7, 8 moderately long ( Fig. 8D View FIGURE 8 ).

Chelipeds slightly unequal ( Fig. 6A View FIGURE 6 ); merus trigonal in cross-section, margins crenulated ( Fig. 6A View FIGURE 6 ); carpus with sharp spine on inner distal angle, with spinule at base ( Fig. 6A View FIGURE 6 ); 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 View FIGURE 6 ).

Ambulatory legs slender; dactylus slender, margins with stiff, spine-like setae; margins of propodus serrate ( Fig. 6A, C View FIGURE 6 ); second ambulatory leg merus about 1.2–1.4 times as long as dactylus (n=4; Fig. 6A View FIGURE 6 ); last leg with propodus about 1.7–1.9 times as long as broad, slightly shorter than dactylus (n=4; Fig. 6A View FIGURE 6 ).

Male pleon triangular, third somite widest ( Fig. 6C View FIGURE 6 ); 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 View FIGURE 6 ); telson width 1.2–1.4 times length, nearly tongue-shaped (n=4; Fig. 6C View FIGURE 6 ).

G1 slender, tip of terminal segment slightly reaching beyond sternal press-button in situ ( Fig. 8D View FIGURE 8 ), subterminal segment about 1.7 times as long as terminal segment ( Fig. 7A View FIGURE 7 ). G1 slightly curved ventrolaterally ( Fig. 8D View FIGURE 8 ); distal part of G1 terminal segment distinctly broader than proximal part ( Fig. 7A View FIGURE 7 ; 10C, D). G2 subterminal segment about 2.3 times as long as terminal segment ( Fig. 7F View FIGURE 7 ).

Female pleon ovate, surface pitted ( Fig. 8A View FIGURE 8 ); sixth somite about 2.7 times as broad as long, telson semicircular, about 2.2 times as broad as long ( Fig. 8A View FIGURE 8 ). Female vulvae on thoracic sternite 6, ovate, opening upward, posterior margin arched distinctly ( Fig. 8B, C View FIGURE 8 ).

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 View FIGURE 6 , 9A View FIGURE 9 ), 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 View FIGURE 6 ) (versus wide and distinct in A. compressum ( Fig. 9D View FIGURE 9 ; 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 View FIGURE 7 ) (versus G1 straight, not reaching sternal press-button, subterminal segment about 2.3 times as long as terminal segment in A. compressum ; Fig. 7C View FIGURE 7 ; 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 View FIGURE 9 ), 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 View FIGURE 7 ), whereas the G1 terminal segment of A. compressum is stick-shaped and uniformly narrow throughout its length ( Fig. 7C View FIGURE 7 ; 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 View FIGURE 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.