Mediapotamon liboense, Wang, Song-bo, Zhou, Xian-min & Zou, Jie-xin, 2019

Wang, Song-bo, Zhou, Xian-min & Zou, Jie-xin, 2019, A new species of freshwater crab of the genus Mediapotamon Tuerkay & Dai, 1997 (Crustacea, Decapoda, Brachyura, Potamidae) from Guizhou, China, ZooKeys 873, pp. 9-23 : 9

publication ID	https://dx.doi.org/10.3897/zookeys.873.36702
publication LSID	lsid:zoobank.org:pub:3E20828E-F1D7-41E9-BA12-0D5F2BD93ED9
persistent identifier	https://treatment.plazi.org/id/69B0792B-F233-403A-ADC2-6666B007F093
taxon LSID	lsid:zoobank.org:act:69B0792B-F233-403A-ADC2-6666B007F093
treatment provided by	ZooKeys by Pensoft
scientific name	Mediapotamon liboense
status	sp. nov.

Treatment

Mediapotamon liboense sp. nov. Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5

Type locality.

China, Guizhou Province: Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, Dongtang Town, Yaozhai Village, Banzhai Hill, 25.2128°N, 108.0041°E, under rock in small hill stream.

Type specimen.

Holotype male, with gonopods in a separate microvial. Original label: "China, Guizhou Province: Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, Dongtang Town, Yaozhai Village, Banzhai Hill, 25.2128°N, 108.0041°E, 10 Oct. 2010, Xian-min Zhou", "NCU MCP 343001". Paratypes, male, same collection data as for holotype, "NCU MCP 343002"; female, same collection data as for holotype, "NCU MCP 343003".

Material examined.

Holotype. CHINA • ♂, NCU MCP 343001, 24.2 × 19.6 mm, Guizhou Province, Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, Dongtang Town, Yaozhai Village, Banzhai Hill, under rock in small hill stream, catch by hand, 10 Oct 2010, Xian-min Zhou leg.

Paratypes. ♂, NCU MCP 343002,19.4 × 15.6 mm • ♀, NCU MCP 343003, 23.4 × 19.0 mm, same collection data as for holotype.

Other material.

♂, NCU MCP 343004, 30.9 × 24.7 mm • 4 ♀♀; NCU MCP 343005, 21.5 × 16.8mm; NCU MCP 343006, 19.2 × 14.6 mm; NCU MCP 343007, 25.0 × 20.0 mm; NCU MCP 343008, 20.0 × 15.8 mm; same collection data as for holotype.

Comparative material.

Mediapotamon angustipedum (Dai & Song, 1982): 2 ♂♂; IZCAS CB 00995, 15.3 × 13.1 mm; IZCAS CB 00988, 18.4 × 16.0 mm; Guangxi Zhuang Autonomous Region, Baise City, Jingxi County, Hurun Town, Xinxing Village, 7 Oct 1978. Mediapotamon leishanense (Dai, 1995): 1♂, IZCAS CB 05181, 14.8 × 11.5 mm, Guizhou Province, Qiandongnan Miao and Dong Autonomous Prefecture, Leishan County, Leigong Mountain, 23 Apr. 1988; 1♂, SYSBM 001094, 15.5 × 12.4 mm, Guizhou Province, Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, coll. C. Huang, Jul 2013. Mediapotamon sp. nov. (sequence number LC155165 in Fig. 8 View Figure 8 ): 1♂, SYSBM 001255, 26.7 × 21.4 mm, 1 ♀, SYSBM 001259, 17.5 × 13.6 mm, Guizhou Province, Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, coll. C. Huang, Jul 2013. Daipotamon minos (Ng & Trontelj, 1996): 1♂, NCU MCP 195501, 20.1 × 16.3 mm, 1 ♀, NCU MCP 195502, 18.8 × 15.1 mm, Guizhou Province, Qiannan Bouyei and Miao Autonomous Prefecture, Lino County, Chaoyang Town, Buyong Village, coll. L. J. Yang, 17 Jul 2010.

Diagnosis.

Carapace trapezoidal, regions indistinct, dorsal surface flat, epigastric cristae indistinct, postorbital cristae convex, cervical groove indistinct, H-shaped groove inconspicuous ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). External orbital angle triangular, epibranchial tooth sharp, anterolateral margin lined with scattered granules, posterolateral surface smooth ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). Third maxilliped exopod with slender flagellum, extending equal to width of merus ( Fig. 1C View Figure 1 ). Male pleon narrow triangular, telson with arc-shaped apex in male ( Fig. 2B View Figure 2 ). G1 slender, terminal segment bend inwards obviously in sub-proximal portion with constant diameter, G1 terminal segment oblique toward dorsal in mesial view in the demarcation between G1/G2 ( Figs 4A, F View Figure 4 , 7A View Figure 7 ). Proximal part of G2 sub-ovate ( Fig. 4C View Figure 4 ). Female vulva large-sized, not reaching suture sternites 5/6, vulval membrane extending outward ( Fig. 3B View Figure 3 ).

Description.

Carapace: outline trapezoidal, width 1.2-1.3 × length (n = 8); dorsal surface flat with numerous pits, anterolateral region wrinkled ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). Epigastric cristae indistinct; cervical groove shallow, indistinct; H shaped groove between gastric and cardiac regions inconspicuous ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). Postorbital cristae slightly convex, not fused with epigastric cristae, separate with epibranchial tooth ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). External orbital angle bluntly triangular, separate with anterolateral margin by conspicuous gap ( Figs 1A, C View Figure 1 , 3A View Figure 3 ). Epibranchial tooth sharp, distinct; anterolateral margin convex laterally, cristae, lined with approximately 9 or10 scattered granules ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). Posterolateral surface smooth, with inconspicuous oblique striae, posterolateral margins converging posteriorly ( Figs 1A, B View Figure 1 , 3A View Figure 3 ). Orbits medium-size; supraorbital margin cristate and lateral portion, infraorbital margins lined with scattered inconspicuous granules ( Fig. 1C View Figure 1 ). Sub-orbital, sub-hepatic and pterygostomial regions covered with low round granules ( Fig. 1C View Figure 1 ). Epistome posterior margin slightly oblique laterally, with broadly triangular median lobe ( Fig. 1C View Figure 1 ).

Third maxilliped: exopod reaching proximal 1/3 of merus length, with slender flagellum extending equal to width of merus ( Figs 1C View Figure 1 , 2C View Figure 2 ). Merus subquadrate, 1.3 times as broad as long, generally flat ( Figs 1C View Figure 1 , 2C View Figure 2 ). Ischium trapezoidal, 1.4 times as long as broad, with distinct median sulcus ( Fig. 2C View Figure 2 ).

Chelipeds (pereiopod 1): slightly unequal ( Fig. 2A View Figure 2 ). Merus surface smooth; carpus surface with pits and a sharp spine at inner-distal angle ( Figs 1A View Figure 1 , 3A View Figure 3 ). Palm of larger chela length 1.4 × height in males (n = 3), 1.5-1.6 × in females (n = 5); dactylus 1 × palm length in males (n = 3), 0.9-1 × in females (n = 5); dactylus as long as pollex ( Figs 1A View Figure 1 , 2A View Figure 2 , 3A View Figure 3 ). Inner margin of fingers with few round blunt teeth, with little gap when fingers closed ( Fig. 2A View Figure 2 ).

Ambulatory legs (pereiopods 2-5): slender; pereiopod 3 merus 0.5 × carapace length in males (n = 3), 0.4 × carapace length in females (n = 5) ( Figs 1A View Figure 1 , 3A View Figure 3 ). Pereiopods 5 propodus 1.9 × as long as broad in males (n = 3), 1.9-2.1 × as long as broad in females (n = 5) ( Fig. 2E View Figure 2 ); shorter than dactylus (n = 8) ( Figs 1A View Figure 1 , 2E View Figure 2 , 3A View Figure 3 ).

Male thoracic sternum: flat and covered with pits; sternites 2-4 broad, width ca. 2 × length; sternites 2 very broad triangular with sharp apex; suture between sternites 2/3 transverse, clear; sternites 3/4 fused but with slight oblique demarcation superficially ( Fig. 2B View Figure 2 ). Male sterno-pleonal cavity deep and narrow, barely reaching anteriorly to level of mid-length of cheliped coxae base; median longitudinal groove present between sternites 7 and 8 medium in length; male pleonal locking tubercle position at middle of sternite 5 ( Fig. 2D View Figure 2 ).

Male pleon: narrow triangular ( Fig. 2B View Figure 2 ); somites 4-6 progressively narrowed distally, lateral margins oblique; telson width 1.3 × length with arc-shaped apex in males (n = 3); somite 6 width 2.4 × length in males (n = 3) ( Fig. 2B View Figure 2 ).

G1: slender ( Figs 4A View Figure 4 , 7A View Figure 7 ); terminal segment bend inwards obviously in the sub-proximal portion with constant diameter, distal end reaching but not beyond pleonal locking tubercle in situ ( Fig. 2D View Figure 2 ); subterminal segment length 2.9 × length of terminal segment ( Figs 4A View Figure 4 , 7A View Figure 7 ). The mesial view of G1 terminal segment not straight but oblique toward dorsal in the demarcation between G1/G2 ( Fig. 4F View Figure 4 ). Basal segment of G2 sub-ovate, subterminal segment length 1.8 × length of distal segment, the distal segment is slender and sharp ( Fig. 4C View Figure 4 ).

Female vulva: large, not reaching sternites 5/6 in situ, with the opening outward and the outer membrane extending outward ( Fig. 3B View Figure 3 ). Reaching approximate three-fifths width of sternite 6 and the position generally distantly each other ( Fig. 3B View Figure 3 ).

Etymology.

The species is named after the type locality, Libo County, Qiannan Bouyei and Miao Autonomous Prefecture, Guizhou Province.

Colour in life.

The overall colour is brownish black, which is similar to the colour of the surrounding environment ( Fig. 5 View Figure 5 ).

Distribution.

The new species is presently known only from the type locality: Libo County, Qiannan Bouyei and Miao Autonomous Prefecture, Guizhou Province.

Ecology.

This species lives in karst mountain locations surrounded by low crests and covered with diverse vegetation ( Figs 6A, B View Figure 6 ). The species lives along the stream flowing down the mountain and remains hidden under rocks during the day.

Remarks.

The new species fits the characteristics of Mediapotamon Türkay & Dai, 1997, viz., carapace intermediate or small in size (15-20 mm), surface smooth without a conspicuous bulge or depression, anterolateral margin lined with granules, male telson triangular, and G1 slender without any projection and reaching the pleonal locking tubercle in situ ( Türkay and Dai 1997). Mediapotamon liboense sp. nov. is similar to M. angustipedum (Dai & Song, 1982), M. leishanense Dai, 1995, and Daipotamon minos , Ng & Trontelj, 1996, but the new species can be differentiated from its congeners by some distinct characters: epibranchial tooth sharp and distinct, anterolateral margin lined with a few scattered granules [versus sharp and distinct in M. angustipedum but blunt and indistinct in M. leishanense , both lined with numerous inseparable granules (cf. Table 2)]; shape of the male telson narrow triangular [versus broad triangular in congeners (cf. Table 2, Fig. 7 View Figure 7 )]; and shape of G1 slender, terminal segment distinctly bent with a constant diameter [versus very slender, terminal segment straight and thinner gradually in M. angustipedum and very slender, terminal segment bent obviously and thinner gradually in M. leishanense (cf. Table 2, Fig. 7 View Figure 7 )]. Its differences compared to D. minos can be found in Table 2 and Figure 7 View Figure 7 .