Migmarma lorentzi, Schubart & Ng, 2020

Schubart, Christoph D. & Ng, Peter K. L., 2020, Revision of the intertidal and semiterrestrial crab genera Chiromantes Gistel, 1848, and Pseudosesarma Serène & Soh, 1970 (Crustacea: Brachyura: Sesarmidae), using morphology and molecular phylogenetics, with the establishment of nine new genera and two new species, Raffles Bulletin of Zoology 68, pp. 891-994 : 968

Migmarma lorentzi , new species

( Figs. 50–52 )

Material examined. Holotype: male (15.8 × 14.0 mm) ( NMBA 625IIa ), Noord River ( = present day Lorentz River ), New Guinea, ca. 4°15′S 138°40′E, coll. Lorentz Expedition 1909 (donated Zoological Museum Amsterdam, 1920). Paratype: 1 female (13.4 × 11.8 mm) ( NMBA 625 IIa), same data as holotype .

Diagnosis. Carapace squarish, slightly longer than wide; dorsal carapace surface smooth, glabrous; epibranchial tooth distinct, separated by deep notch; posterolateral margins subparallel; outer surface of chela gently rugose, smooth flattened granules, outer surface gently convex, not flat, ventral margin of palm gently concave; suture between male thoracic sternites 3 and 4 distinct; ambulatory merus short, broad; male pleon subrectangular, telson rounded, slightly sunken into distal margin of somite 6; G1 slender, gently curved, chitinous distal part long, tapering, relatively slender, subspatuliform, tip appears bifurcated.

Etymology. The species is named after Hendrikus Albertus Lorentz, the Dutch explorer for whom its type locality river is also named.

Remarks. In having the male telson only slightly sunken into somite 6, Migmarma lorentzi , new species, superficially resembles species of Bresedium , notably B. laevimanum , but can easily be separated by the male telson being rounded and the pleonal somite 6 less broad ( Fig. 50E ) (versus telson more elongate and somite 6 is wider and more rectangular in shape in B. laevimanum ; Figs. 31F–H , 42A ); and the G1 is also proportionately stouter and the tip of the chitinous distal part is tapering and sharp ( Figs. 50F–K , 51A–E ) (versus G1 proportionately more slender and the tip of the chitinous distal part is flared in B. laevimanum ; Fig. 42B–E ).

Figures

Fig. 50. Migmarma lorentzi, new species, holotype male (15.8 × 14.0 mm) (NMBA 625IIa), Lorentz River, Irian Jaya, Indonesia. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, outer view of right chela; E, anterior thoracic sternum and pleon; F–H, left G1; I–K, distal part of left G1.

Fig. 51. Migmarma lorentzi, new species, holotype male (15.8 × 14.0 mm) (NMBA 625IIa), Lorentz River, Irian Jaya, Indonesia. A, left G1 (ventral view); B, left G1 (dorsal view); C, distal part of left G1 (ventral view); D, distal part of left G1 (dorsal view); E, distal part of left G1 (mesial view); F, left G2. Scales = 0.5 mm.

Fig. 52. Migmarma lorentzi, new species, paratype female (13.4 × 11.8 mm) (NMBA 625IIa), Lorentz River, Irian Jaya, Indonesia. A, overall habitus; B, vulvae.

Fig. 31. Male anterior thoracic sternum and pleon. A, Contusarma bocourti, male (25.3 × 23.3 mm) (ZRC 2000.0952), Bangkok, Thailand; B, Contusarma cheirogonum, male (15.3 × 14.0 mm) (ZRC 2011.0924), Pulau Tioman, Malaysia; C, Contusarma cheirogonum, neotype male (24.5 × 21.5 mm) (ZRC 1995.225), Bako National Park, Sarawak; D, Miersarma granosimanum, lectotype male (16.9 × 14.8 mm) (NHM 1880.6), Borneo; E, Miersarma granosimanum, male (22.5 × 19.2 mm) (ZRC 1965.7.29.164), Sedili River, Johor, Malaysia; F, Bresedium laevimanum, lectotype male (20.0 × 17.6 mm) (MNHG), Borneo; G, Bresedium laevimanum, male (26.3 × 23.7 mm) (NHM) (lectotype of Sesarma sediliensis), Johor, Malaysia; H, Bresedium laevimanum, male (21.2 × 18.2 mm) (ZRC 1965.7.29.121), Johor, Malaysia.

Fig. 42. A–E, Bresedium laevimanum, lectotype male (20.0 × 17.6 mm) (MNHG), Borneo. A, male pleon; B, left G1 (ventral view, denuded); C, left G1 (dorsal view, denuded); D, left distal part of G1 (ventral view, denuded); E, left distal part of G1 (dorsal view, denuded). Scales: A = 2.0 mm; B, C = 1.0 mm; D, E = 0.5 mm.