Qianguimon rongxianense, Wang & Huang & Zou, 2019

Wang, Song-Bo, Huang, Chao & Zou, Jie-Xin, 2019, Hylomus Cook & Loomis 1924, Zoological Studies 58 (31), pp. 1-10 : 2-5

publication ID	https://doi.org/ 10.6620/ZS.2019.58-31
persistent identifier	https://treatment.plazi.org/id/03F287B9-8276-437A-F1CE-DB38FEE2FD75
treatment provided by	Felipe
scientific name	Qianguimon rongxianense
status

Treatment

Family Potamidae Ortmann, 1896 View in CoL Subfamily Potamiscinae Ortmann, 1896 Genus Qianguimon Huang, 2018

Qianguimon rongxianense sp. nov. ( Figs. 1–4 View Fig View Fig View Fig View Fig ) urn:lsid:zoobank.org:act:ED6D2D89-7DE3-457B-8043-CB3925CE19E3

Type material: Holotype: ò (15.2 × 12.8 mm) ( NCU MCP 118401 View Materials ), Shan Xin Dui (22.5049°N, 110.7282°E), Sixian Village , Licun Town , Rong County, Yulin City, Guangxi Zhuang Autonomous Region , small stream, coll. Ye-Song Cheng, August 23, 2007 GoogleMaps . Paratypes: 1ñ (allotype) (20.4 × 16.0 mm) ( NCU MCP 118403), same data as holotype; 1ò (14.9 × 12.6 mm) ( NCU MCP 118402).

Additional material examined: 4òò (14.3 × 12.2 mm, 13.3 × 11.7 mm, 15.9 × 13.5 mm, 15.8 × 13.6 mm) ( SYSBM, NCU MCP 118405, 118406, 118410), same data as holotype; and 3ññ (16.6 × 14.1 mm, 20.1 × 17.1 mm, 17.7 × 14.4 mm) ( NCU MCP 118407, 118408, 118409), same data as holotype.

Etymology: This species is named after the type locality, Rong County, Yulin City, Guangxi Zhuang Autonomous Region, southern China.

Description: Carapace subquadrate, about 1.2 times as wide as long (n = 10); regions indistinct, dorsal surface slightly convex, pitted, anterolateral region weakly rugose ( Figs. 1A, B View Fig , 3A View Fig ). Front slightly deflexed, margin slightly ridged in dorsal view ( Figs. 1A, B View Fig , 3A View Fig ). Epigastric cristae prominent, separated by narrow gap ( Figs. 1A, B View Fig , 3A View Fig ). Postorbital cristae sharp, laterally expanded, not fused with epigastric cristae or epibranchial teeth ( Figs. 1A, B View Fig , 3A View Fig ). Branchial regions not inflated ( Figs. 1A, B View Fig , 3A View Fig ). Cervical groove shallow, inconspicuous, H shaped groove between gastric and cardiac regions depressed ( Figs. 1A, B View Fig , 3A View Fig ). Mesogastric region slightly convex ( Figs. 1A, B View Fig , 3A View Fig ). External orbital angle bluntly triangular, almost confluent with anterolateral margin. Epibranchial tooth small, granular, indistinct ( Figs. 1 View Fig , 3A View Fig ). Anterolateral margin cristate, lined with approximately 16–20 granules; bent inward posteriorly ( Figs. 1A, B View Fig , 3A View Fig ). Posterolateral surface with low, oblique striae, converging towards posterior carapace margin ( Figs. 1A, B View Fig , 3A View Fig ). Orbits large; supraorbital and infraorbital margins cristate, lined with numerous granules ( Fig. 1C View Fig ). Sub-orbital and upper parts of pterygostomial regions covered with granules; sub-hepatic regions lined with oblique striae ( Fig. 1C View Fig ). Posterior margin of epistome narrow, concave; median lobe sharply triangular, lateral margins straight ( Fig. 1C View Fig ).

Maxilliped 3 exopod reaching proximal 1/4 of merus length, with short flagellum ( Fig. 2B View Fig ). Merus trapezoidal, about 1.1 times as broad as long, with median depression ( Fig. 2B View Fig ). Ischium trapezoidal, about 1.5 times as long as broad, with distinct median sulcus ( Fig. 2B View Fig ).

Chelipeds (pereiopod 1) unequal ( Figs. 1A View Fig , 2A View Fig , 3A View Fig ). Carpus surface wrinkled with sharp spine at innerdistal angle with spinule at base ( Figs. 1A View Fig , 3A View Fig ). Palm of larger chela about 1.3–1.4 times as long as high in males (n = 6), 1.5–1.6 times in females (n = 4); dactylus 0.7 times as long as palm in males (n = 6), 0.7–0.8 times in females (n = 4) ( Figs. 1A View Fig , 2A View Fig , 3A View Fig ). Inner margin of fingers with granular teeth, with small gap when fingers closed ( Fig. 2A View Fig ).

Ambulatory legs (pereiopods 2–5) slender, with setae; pereiopod 3 merus 0.5 times as long as the carapace in males (n = 6), 0.4 times in females (n = 4) ( Figs. 1A View Fig , 3A View Fig ). Pereiopods 5 propodus 1.5–1.6 times as long as broad in males (n = 6), 1.6 times in females (n = 4), about as long as dactylus ( Figs. 1A View Fig , 3A View Fig ).

Male thoracic sterum generally smooth, pitted; sternites 1–4 broad, about 1.6 times as wide as length; sternites 1, 2 forming triangular structure, with obvious suture; suture between sternites 2, 3 inconspicuous; sternites 3, 4 fused without obvious boundary ( Fig. 2C View Fig ). Male sterno-pleonal cavity relatively deep, barely reaching anteriorly to level of midlength of cheliped coxae base; median longitudinal groove between sternites 7, 8 deep and medium ( Fig. 2D View Fig ). Male pleonal locking tubercle positioned at mid-length of sternite 5 ( Fig. 2D View Fig ). Female vulvae ovate, medium-sized, reaching proximal three-quarters width of sternite 6, lateral margin with wide rim ( Fig. 3B View Fig ).

Male pleon triangular ( Fig. 2C View Fig ); somites 3–6 progressively narrower longitudinally, lateral margins slightly concave; somite 6 about 1.3–1.4 times as wide as long in males (n = 6); telson about 2.1 times as wide as long with rounded apex in males (n = 6) ( Fig. 2C View Fig ). Female pleon broadly ovate.

G1 slender, tip of terminal segment exceeding pleonal locking tubercle, almost reaching suture between thoracic sternites 4/5 ( Fig. 2D View Fig ); subterminal segment about 1.6 times length of terminal segment, groove for G2 starts at mid-point; terminal segment boot-shaped, with large triangular sub-distal projection, outer-distal margin swollen ( Fig. 4A–C View Fig ). G2 subterminal segment about 1.8 times length of distal segment, with subovate base and flagelliform distal segment ( Fig. 4D View Fig ).

Remarks: The new species has a boot-shaped G1 terminal segment typical of that of congeners, but markedly distinct in some characters. Its small size (CW <20 mm) [(versus <30 mm in Q. aflagellum (Dai, Song, Li & Liang, 1980) and <40 mm in Q. elongatum Huang, 2018 and Q. splendidum Huang, 2018 (cf. Table. 1)], confluent external orbital angle and anterolateral region ( Figs. 1 View Fig , 3A View Fig ) [versus separated by narrow gap in all other Qianguimon (cf. Table. 1)], short third maxilliped exopod flagellum ( Fig. 2B View Fig ) [versus very short to absent in all other Qianguimon (cf. Table. 1)], and swollen outer-distal margin of the G1 terminal segment [versus not swollen in all other Qianguimon (cf. Table. 1)] immediately set it apart from the other species. Qianguimon rongxianense sp. nov. also resembles species from Yarepotamon Dai & Türkay, 1997 and Eurusamon Huang, 2018 , but its boot-shaped G1 ( Fig. 4A–C View Fig ) and medium-sized, widerimmed vulvae ( Fig. 3B View Fig ) separate it from these species. These comparisons are listed in table 1.

Distribution: The new species is known only from type locality presently, Rong County, Yulin City, Guangxi Zhuang Autonomous Region.

Phylogenetic relationships

The 16S rDNA sequences of 61 species from 41 genera of potamid crabs, including the new species, which have been published in GenBank, were used for alignment analysis with a total length of 461 bp. The localities and access numbers of these species are listed in figure 5. Overall, the phylogenetic trees constructed by the different methods showed a generally similar topological structure with some well supported terminal nodes, but most basal nodes are very weakly supported ( Fig. 5 View Fig ). The results shows that the new species is clustered with Qianguimon and Eurusamon (weak support) in a clade (high support from BI analysis) within the China-East Asia Islands Clade ( Shih et al. 2009) that contains other genera from southern China such as Cantopotamon Huang, Ahyong & Shih, 2017 , Chinapotamon Dai & Naiyanetr, 1994 , Cryptopotamon Ng, 1992 , Diyutamon Huang, Shih & Ng, 2017 , Huananpotamon Dai & Ng, 1994 , Minpotamon Dai & Türkay, 1997 , Minutomon Huang, Mao & Huang, 2014 , Nanhaipotamon Bott, 1968 and Yarepotamon Dai & Türkay, 1997 .