Glabrithelphusa angene, Meyer, Kirstin S., Cumberlidge, Neil & Koppin, Jennifer C., 2014

Glabrithelphusa angene , n. sp.

( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 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 View FIGURE 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 View FIGURE 1 A, 3A). Entire dorsal surface of carapace smooth ( Fig. 1 View FIGURE 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 View FIGURE 1 B, 3C). Epimeral sulcus heavily granular between suborbital, anterior pterygostomial regions, smooth posteriorly. Epistomial tooth triangular, deflexed, edges smooth ( Fig. 1 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 2 F, 3B); anterior sternoabdominal cavity smooth, lacking dense setae ( Fig. 2 View FIGURE 2 F, 3B). Episternal sulci s4/e4, s5/e5, s6/e6, s7/e7 absent, smooth ( Fig. 2 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 2 B, 4A,C,). G1, G2 subterminal segments equal in length, but G2 terminal article twice as long as G1 terminal article ( Fig. 2 View FIGURE 2 C, 4E). G2 terminal article long, well-developed, straight, no distal curve, one-half length of G2 subterminal segment ( Fig. 2 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 1 A, 3A) (versus strong carinae on the posterior dorsal carapace in F. raimundi and F. goudoti ( Reed & Cumberlidge 2006 Fig. 1 View FIGURE 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 View FIGURE 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.