Ceratoplax margarita n. sp., a new rhizopine crab (Crustacea: Brachyura: Pilumnidae) from Papua New Guinea, with rediagnoses of C. truncatifrons Rathbun, 1914, and C. fulgida Rathbun, 1914 Author Ng, Peter K. L. Author Clark, Paul F. text Zoosystema 2015 2015-06-30 37 2 323 331 http://dx.doi.org/10.5252/z2015n2a2 journal article 10.5252/z2015n2a2 1638-9387 5155702 urn:lsid:zoobank.org:pub:DF6FC413-9BD1-459B-BC25-FB8F6A0FD339 Ceratoplax fulgida Rathbun, 1914 ( Figs 3 ; 4 D-I) Ceratoplax fulgida Rathbun, 1914: 146 . — Tesch 1918: 55 (key); Serène 1968: 91 (list). — Ng 1987: 78 , 88 (discussion). — Ng et al. 2008: 143 (list). FIG. 2. — Ceratoplax truncatifrons Rathbun,1914 : A , E , ♂, 4.0 × 2.5 mm,(NNM-ZMA Crust De 203018),Indonesia; B , D , ♂, 5.2 × 3.3 mm,(NNM Cru D-2164),Indonesia; C , ♀, 5.6 × 3.5 mm,(NNM-ZMA Crust De 203018),Indonesia. A -C , overall dorsal views; D , E , anterior thoracic sternums and abdomens.Scale bars:1.0 mm. TYPE MATERIAL . — Holotype : Near Marinduque Island, ♂ , 7.1 × 4.3 mm , ( USNM 46401). Paratype : 1 ♀ , 6.3 × 4.1 mm , ( USNM 46401), stn 5371, near Marinduque Island: Tayabas Light (outer), north 43° west , 6 miles , 13°49’40”N , 121°40’15”E , 83 fms, coll. R . V . Albatross , 24.II.1909 . DIAGNOSIS. — Carapace transversely subovate, width 1.54-1.65 × length; dorsal surfaces smooth, glabrous, regions poorly demarcated, H-shaped gastric grooves barely discernible; anterolateral margin strongly convex, entire to weakly dentate with three small clefts, reaching along ⅔ of lateral margin, submarginal parts smooth, not clearly demarcated from posterolateral margin; posterolateral margins gently concave, gradually converging to gently convex posterior carapace margin ( Figs 3A ; 4H, I ). Frontal margin weakly divided into two low subtruncate lobes from dorsal view, gently confluent with supraorbital margin; with low external orbital tooth ( Figs 3A ; 4H, I ). Orbit ovate, small, eyes with small cornea, fused to carapace, immovable ( Fig. 3B ). Posterior margin of epistome gently convex, not clearly divided into lobes ( Fig. 3B ). Anteroexternal angle of merus of third maxilliped with rounded auriculiform structure; exopod stout ( Fig. 4G ). Male thoracic sternum wide, sternites 1 and 2 completely fused to form wide triangular structure; separated from fused sternites 3 and 4 by distinct sinuous suture ( Fig. 3C ). Male abdomen T-shaped; somite 6 rectangular, wider than long; telson triangular, elongate, much longer than somite 6 ( Fig. 3C ). Chelipeds stout, carpus with subdentiform inner angle and tuft of setae, outer angle sharp but not spiniform or dentiform; chela stout, fingers shorter than palm ( Fig. 3A, D, E ). Ambulatory legs, long; articles slender, unarmed; dactylus of last leg upcurved ( Fig. 3A ). G1 distinctly sinuous, subdistal part gently merging with tapering tip that is gently bent, opening slender ( Fig. 4 D-F). FIG. 3. — Ceratoplax fulgida Rathbun, 1914 , holotype ♂, 7.1 × 4.3 mm (USNM 46401), Philippines: A , overall dorsal view; B , frontal view of carapace; C , anterior thoracic sternum and abdomen; D , outer view of right chela; E , outer view of left chela. Scale bars: 1.0 mm. TYPE LOCALITY . — Tayabas Light (outer), near Marinduque Island, north 43° west , 6 miles , 13°49’40”N , 121°40’15”E . DISTRIBUTION. — Known only from the type locality. REMARKS The type series for this species (and the only known specimens) is represented by a male and a female, but it is by no means certain both are conspecific. Although the female paratype specimen looks similar to the male holotype , its anterolateral margin has small clefts marking four low and broad lobes ( Fig. 4I ). In the holotype male, the anterolateral margin is entire ( Figs 3A ; 4H ). Whether this is mere variation can only be ascertained with more material. See discussion for Ceratoplax margarita n. sp.