Migmarma lustrum, 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 lustrum , new species

( Figs. 47–49 )

Material examined. Holotype: male (15.7 × 13.9 mm) ( ZRC 2010.0021 ), in base of leaf of sago palm ( Metroxylon sagu ), inland sago swamp, moist secondary lowland forest, village of Lilinta , Misool Barat , Raja Ampat Province , Irian Jaya, Indonesia, D. Telmov & K. Cureke, 1 April 2009.

Diagnosis. Carapace somewhat trapezoidal; dorsal carapace surface uneven but not setose; epibranchial tooth distinct, separated by deep notch; posterolateral margins slightly divergent; outer surface of chela covered with small granules, those on margins relatively sharper, outer surface gently convex, not flat, ventral margin of palm concave; suture between male thoracic sternites 3 and 4 distinct; ambulatory merus short, broad; male pleon triangular, telson relatively elongate, not sunken into distal margin of somite 6; male pleonal somite 6 broad; G1 slender, gently curved, chitinous distal part long, relatively slender, subspatuliform, tip subtruncate.

Etymology. The name is derived from the Latin word for swamp or bog, “lustrum”. The name is used as a noun in apposition.

Remarks. Migmarma lustrum , new species, is morphologically similar to M. modestum except that the ventral margin of the cheliped palm is gently concave and the outer surface is not flat ( Fig. 47E, F ) (versus ventral margin almost straight and the outer surface flat in B. modestum ; Fig. 45F ); the male pleonal somite 6 is less broad ( Fig. 47G, H ) (versus proportionately broader in B. modestum ; Figs. 45D , 46B ); and most significantly, the G1 is more slender with the chitinous distal part distinctly more elongate ( Figs. 48C–G , 49A–E ) (versus G1 stouter with the chitinous distal part short and stout in B. modestum ; Figs. 45G–K , 46C–H ).

Figures

Fig. 47. Migmarma lustrum, new species, holotype male (15.7 × 13.9 mm) (ZRC 2010.0021), Irian Jaya, Indonesia. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, left third maxilliped; E, outer view of right chela; F, outer view of left chela; G, anterior thoracic sternum and pleon; H, pleon.

Fig. 48. Migmarma lustrum, new species, holotype male (15.7 × 13.9 mm) (ZRC 2010.0021), Irian Jaya, Indonesia. A, thoracic sternites 1–4; B, sternopleonal cavity; C, frontal view of cephalothorax; D, outer view of right chela; E, anterior thoracic sternum and pleon; C, D, left G1; E–G, distal part of left G1.

Fig. 49. Migmarma lustrum, new species, holotype male (15.7 × 13.9 mm) (ZRC 2010.0021), 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. 45. Migmarma modestum, holotype male (25.0 × 20.9 mm) (SMF 1989), Indonesia. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, sternopleonal cavity; F, outer view of right chela; G, H, left G1; I–K, distal part of left G1.

Fig. 46. Migmarma modestum, holotype male (25.0 × 20.9 mm) (SMF 1989), Indonesia. A, left third maxilliped (denuded); B, pleon; C, left G1 (ventral view); D, left G1 (dorsal view); E, distal part of left G1 (ventral view); F, distal part of left G1 (mesial view); G, distal part of left G1 (dorsal view); H, distal part of left G1 (mesial view); I, left G2. Scales: A, C, D, I = 1.0 mm; B = 5.0 mm; E–H = 0.5 mm.