Calcipotamon puglabrum Huang & Huang & Shen 2020, gen. nov. et sp. nov.
Creators: name: Huang, Chao
name: Huang, Sheng-Zhuo
name: Shen, Zhi-Xin
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Potamidae
Calcipotamon
Calcipotamon puglabrum

description: Calcipotamon puglabrum gen. nov. et sp. nov.
urn:lsid:zoobank.org:act: 48E1B266-D473-4754-ABE1-BF56FCEDBDC
[Chinese name: ÄẌṘĀae]
(Figs. 1–3, 5)
Type material. Holotype: SYSBM 001961, male (31.6 × 24.5 mm), Wangxia Village (19.00°N, 109.15°E), Changjiang Li Autonomous County, Hainan Province, China, rock crevice in karst forest, 600-900 m a.s.l., coll. C. Huang, June, 2019. Paratypes: SYSBM 001962, male (30.3 × 23.8 mm), same data as holotype. SYSBM 001963-001964, 2 females (39.7 × 30.9 mm, 31.5 × 24.6 mm), same data as holotype. AM P.104569, male (29.3 × 22.6 mm), same data as holotype. AM P.104570, female (30.4 × 23.7 mm), same data as holotype.
Description. Carapace broader than long, width 1.3 × length (n = 6), regions indistinct. Dorsal surface smooth, finely pitted, convex (Fig. 1). Front deflexed, margin slightly ridged in dorsal view (Fig. 1). Epigastric cristae low, blunt, divided by a narrow gap (Figs. 1, 2A). Postorbital cristae smooth, very low (Fig. 1). Branchial regions swollen; cervical groove very shallow; mesogastric region convex (Fig. 1). External orbital tooth prominent, sharp, triangular with almost straight outer margins, separated from anterolateral margin by gap (Figs. 1, 2A). Epibranchial tooth blunt (Figs. 1, 2A). Anterolateral margin cristate, lined with smoothly fused granules. Posterolateral surface smooth (Fig. 1). Orbits large, supraorbital and infraorbital margins ridged, smooth (Figs. 1, 2A). Sub-orbital, subhepatic and pterygostomial regions divided by sutures; surfaces smooth (Fig. 2A). Epistome median lobe broadly triangular, lateral margins sinuous (Fig. 2A).
Maxilliped III merus width about 1.1 × length; ischium width about 0.7 × length; merus subtrapezoidal with median depression; ischium subtrapezoidal, with distinct median sulcus, mesial margin rounded; exopod reaching to proximal one-fifth of merus height, flagellum very short to absent (Fig. 3A).
Chelipeds (pereiopod I) unequal (Figs. 1, 3 F–G). Merus trigonal in cross section, margins weakly crenulated, surfaces generally smooth (Figs. 1, 2A). Carpus with sharp spine at inner-distal angle, spinule at base, surfaces smooth (Fig. 1). Major cheliped palm length about 1.5–1.6 × height in males (n = 2), 1.5–1.7 × in females (n = 3); dactylus 0.9–1.0 × palm length in both males (n = 2) and females (n = 3) (Fig. 3 F–G). Palm surface smooth, pitted. Occlusal margin of fingers lined with large and small blunt, round teeth; small gape when closed (Fig. 3 F–G).
Pereiopods II–V (first to fourth ambulatory legs) slender, smooth. Pereiopod III merus 0.9 × carapace length in males (n = 3) and females (n = 2). Pereiopods V propodus 3.8–4.0 × as long as broad in males (n = 3), and 4.0–4.1 × in females (n = 3), shorter than dactylus (Fig. 1). Male thoracic sternum generally smooth, pitted; sternites I–IV relatively narrow, width 1.5 × as length. Sternites I, II fused, forming a subtriangular structure; sternites II, III fused, separated by a deep transverse sulcus; sternites III, IV fused, with inconspicuous sulcus (Fig. 2B). Male sterno-pleonal cavity reaching anteriorly to level of midlength of chelipeds coxae base (Fig. 2B); median longtitudinal groove separating sternites VII, VIII deep (Fig. 2D). Male pleonal locking tubercle positioned posterior to mid-length of sternites V (Fig. 2D). Female vulva ovate, medium-sized, with relatively wide outer rim, reaching sternite suture V/VI but not VI/VII; positioned closely to one another, orientation slightly oblique to the longitudinal axis of pleon (Fig. 2F).
Pleon narrowly triangular in males (Fig. 2C) and broadly ovate in females (Fig. 2E). Male pleonites III–VI progressively narrower, lateral margins almost straight; pleonite VI 2.1 × as broad as long; telson 1.4 × as broad as long, with blunt apex (Fig. 2C).
G1 generally slender, reaching beyond the pleonal locking tubercle but not to sternites IV/V suture in situ (Fig. 2D). Subterminal segment 2.7–2.9 × as long as terminal segment (n=3), tapering anteriorly, inner margin slightly convex to convex, outer margin slightly concave. Terminal segment elongated, basal region curved anterolaterally, apex pointed anteriorly, with large rounded basal flap and sharp tip (Fig. 3 C–E, H–I). G2 subterminal segment 1.7–1.9 × as long as the flagellum-like terminal segment (n=3) (Fig. 3B).
Etymology. The species name is an arbitrary combination of Latin “purpura” and “glaber”, which means purple and smooth. The name is used as a noun in apposition.
Colour in life. Generally dark purple. Joints of chelipeds and ambulatory legs, orbit margins, posterior margin of epistome and upper inner margins of pterygostomial regions orange (Fig. 5A).
Habitat. This terrestrial species is found from a karstic mountain where they hide in the water-filled crevices of limestone outcrop formed by weathering (Fig. 5B). Suitable crevices were almost all occupied by at least one crab at the type locality. The new species possesses slender legs which give it increased climbing abilities and mobility on land, which is likely an adaptation to the volatile nature of their preferred habitat and their predatory nature. One specimen was found residing inside a water-filled tree hole, suggesting some plasticity in habitat choice. Several ovigerous females were found during our collection in June but were released after inspection. No other potamids were observed at the type locality.
Remarks. See remarks for genus.
Distribution. Wangxia Village, Changjiang Li Autonomous County, Hainan, China.
description: Published as part of Huang, Chao, Huang, Sheng-Zhuo & Shen, Zhi-Xin, 2020, A new long-legged terrestrial freshwater crab, Calcipotamon puglabrum gen. nov et sp. nov. (Crustacea: Decapoda: Potamidae), from Hainan Island, China, pp. 447-456 in Zootaxa 4766 (3) on pages 452-454, DOI: 10.11646/zootaxa.4766.3.4, http://zenodo.org/record/3765589