Glabrithelphusa angene Meyer, Cumberlidge & Koppin, 2014, n. sp.
Creators: name: Meyer, Kirstin S.
name: Cumberlidge, Neil
name: Koppin, Jennifer C.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Potamonautidae
Glabrithelphusa
Glabrithelphusa angene

description: Glabrithelphusa angene, n. sp.
(Figs 1–4)
Material examined. MADAGASCAR. Adult male holotype by present designation (cw 41.5, cl 29.3, ch 15.3, fw 12.4 mm), no locality or collection information (MNHN-IU-2013-11978). Paratypes: 4 adult males (cw 40.4, cl 29.0, ch 14.9, fw 11.3 mm; cw 37.4, cl 27.9, ch 15.1, fw 10.6 mm; cw 45.4, cl 32.7, ch 17.0, fw 13.0 mm; cw 43.6, cl 31.8, ch 16.6, fw 12.3 mm), 3 adult females (cw 36.9, cl 28.6, ch 16.7 fw 10.8 mm; cw 36.5, cl 27.6, ch 14.8, fw 10.6 mm; cw 39.2, cl 28.4, ch 14.9, fw 10.5 mm) (MNHN-IU-2013-11979), same data as holotype.
Type locality. Madagascar. Exact locality and habitat unknown.
Distribution. Only known from Madagascar.
Diagnosis. As for genus.
Description (based on holotype, adult male cw 41.5 mm). Carapace (Fig. 1 A, 3A) outline transversely oval, high (ch/fw 1.34); front narrow (fw/cw 0.27), deflexed; epibranchial, exorbital teeth small, low; space or cleft between epibranchial tooth and exorbital tooth reduced to small but distinct shallow notch; anterolateral margin evenly curved outward, completely smooth. Postfrontal crest faint, incomplete, postorbital crests, epigastric crests poorly defined, positioned well forward almost in line with postorbital margins; short, broad shallow mid-groove between epigastric crests; cardiac, urogastric grooves shallow, cervical grooves faint, short (Fig. 1 A, 3A). Entire dorsal surface of carapace smooth (Fig. 1 A, 3A). Suborbital, subhepatic regions of carapace sidewall completely smooth, pterygostomial region with fields of carinae near buccal margin, fading to smooth posteriorly; vertical sulcus on carapace sidewall curved, raised, faintly granular, running from base of epibranchial tooth to epimeral sulcus (Fig. 1 B, 3C). Epimeral sulcus heavily granular between suborbital, anterior pterygostomial regions, smooth posteriorly. Epistomial tooth triangular, deflexed, edges smooth (Fig. 1 B, 3C). Third maxilliped exopod long, reaching beyond ischium/merus junction, exopod flagellum long reaching beyond superior margin of third maxilliped merus; ischium with deep, wide vertical sulcus (Fig. 1 C, 3B,C). Mandibular palp 2-segmented with small, hard, anterior lobe at junction between segments, 0.25x length of terminal segment (Fig. 2 D,E). Sternal sulcus s1/s2 short, very faint; sternal sulcus s2/s3 completely crossing sternum; sternal sulcus s3/s4 reduced to 2 short, deep notches at margins (Fig. 2 F, 3B); anterior sternoabdominal cavity smooth, lacking dense setae (Fig. 2 F, 3B). Episternal sulci s4/e4, s5/e5, s6/e6, s7/e7 absent, smooth (Fig. 2 F, 3B). Male abdomen slim, triangular, tapered, widest at a3, narrowest at a7 (telson); telson outline forming triangle with rounded apex, straight sides, broad base (Fig. 2 F, 3B). Sternal groove s4/s5 meeting a7 well past a6/a7 junction; sternal groove s6/s7 close to a6/ a7 junction, meeting a6 3/4 of segment length from a6/a5 (Fig. 2 F, 3B).
G1 terminal article short (length of terminal article to subterminal segment ratio 0.23), slim, with short setae, tapering to broad tip, directed outward, straight; medial fold on ventral terminal article raised; lateral fold not raised, folds basally separated, meeting midway along ventral face of article to form longitudinal groove that continues to tip of article; groove not visible on dorsal face; distal third of subterminal segment of G1 slim, curving outward for short distance near junction of terminal article with subterminal segment, with raised rounded shoulder on subterminal segment external margin (Fig. 2 AB, 4A,B,C,D). Junction between G1 terminal article, subterminal segment clearly visible on ventral side. G1 terminal article, subterminal segment separated on dorsal side by broad, subtriangular dorsal membrane; dorsal membrane superior margin formed by horizontal basal margin of terminal article, inferior margin of membrane formed by U-shaped distal edge of subterminal segment; lateral, medial margins of dorsal membrane narrow (Fig. 2 B, 4A,C,). G1, G2 subterminal segments equal in length, but G2 terminal article twice as long as G1 terminal article (Fig. 2 C, 4E). G2 terminal article long, well-developed, straight, no distal curve, one-half length of G2 subterminal segment (Fig. 2 C, 4E).
Dactylus of both chelipeds relatively slender, approximately one-third height of palm, cutting edge lined by small, even teeth; upper margin of dactylus smooth; lower margin of propodus slightly indented (Fig. 1 F,G). Fixed finger of propodus of major (right) cheliped slender with 3 unfused molars in proximal region followed by series of small pointed teeth (Fig. 1 F). First carpal tooth on inner margin of cheliped carpus large, pointed; second carpal tooth smaller, pointed, followed by series of very small teeth (Fig. 1 D). Medial, lateral, margins of inferior face of cheliped merus smooth, inferior face with small pointed, distal meral tooth; superior margin, superior face of cheliped merus smooth; cheliped ischium rounded, smooth (Fig. 1 D,E). Walking legs p2‒p5 normal length, not elongated (p5 merus/cw = 0.32), inner margins of propodi of p2‒p5 smooth (Fig. 3 A,B).
Remarks. The new species is distinguished from other species of Madagascan freshwater crabs by a unique suite of characters of the mandible, carapace, and gonopods (see Remarks for genus). The specimens described here are morphologically closest to the three species of the genus Foza (Reed & Cumberlidge 2006; Cumberlidge & Meyer 2009). Glabrithelphusa angene n. sp. can be distinguished from these by its completely smooth dorsal carapace (Fig. 1 A, 3A) (versus strong carinae on the posterior dorsal carapace in F. raimundi and F. goudoti (Reed & Cumberlidge 2006 Fig. 1 B; Cumberlidge & Meyer 2009)), by granules on the anterolateral carapace surface in F. ambohitra Cumberlidge & Meyer 2009 Table 1), and by its mandible with a shortened anterior lobe, 0.25x terminal segment length (Fig. 1 D,E) (versus a mandible with a large anterior lobe, 0.5x terminal segment length (Reed & Cumberlidge 2006; Cumberlidge & Meyer 2009)).
Etymology. The specific name angene is a combination derived from the names of the first author’s parents (Angela and Gene Meyer) used as a noun in apposition and is in recognition of their contributions to her education.
description: Published as part of Meyer, Kirstin S., Cumberlidge, Neil & Koppin, Jennifer C., 2014, A new genus and species of freshwater crab from Madagascar (Decapoda, Brachyura, Potamoidea, Potamonautidae), pp. 65-72 in Zootaxa 3884 (1) on pages 68-71, DOI: 10.11646/zootaxa.3884.1.5, http://zenodo.org/record/287450