Nanoplax Guinot, 1967

Felder, Darryl L., 2020, A new crab of the genus Nanoplax from the Gulf of Mexico, and assignment of Micropanope pusilla to a new genus (Crustacea, Brachyura, Pseudorhombilidae), Zootaxa 4810 (3), pp. 531-545 : 532

Nanoplax Guinot, 1967

Nanoplax Guinot 1967: 362 ; 1971: 1076; Martin & Abele 1986: 194; Hendrickx 1998: 642: (key); Ng et al. 2008: 192.

Type species. Panopeus xanthiformis A. Milne-Edwards, 1880 ; reassigned as Micropanope xanthiformis (A. Milne-Edwards, 1880) by Rathbun (1930) prior to diagnosis of Nanoplax by Guinot (1967: 362–363).

Emended diagnosis. Carapace wider than long, hexagonal, distinctly areolated, anterolateral border slightly convex, bearing 5 teeth; first anterolateral tooth (outer orbital angle) small; second lobiform, separated from first by shallow depression; third strongly triangular, acute tip directed anteriorly, fourth strongly triangular, spiniform tip directed anterolaterally; fifth small, acutely spiniform (sometimes obsolescent in young). Front advanced, slightly deflected, weakly convex to subtruncate lobes separated from the orbital edge by furrow. Orbits, eyestalks slightly elongate. Antennal flagellum long, first article separated from anterior edge of pterygostomium by exposed narrow plate. Mouthframe widening anteriorly, median notch marking strong median endostomal suture of buccal plate, well-defined endostomal ridge to either side of median suture. Maxilliped 3 merus anterolateral corner produced, protruding, exopodite relatively short, broad, heavy. Cheliped strongly developed, somewhat elongate, carpus quadrangular in outline, inner corner bispinose, fingers of chelae elongate. Ambulatory legs long and narrow, upper margins of meri armed by small spines. Thoracic sternum wide, sternopleonal cavity of male fourth sternite forming distinct submedian pockets accommodating distal ends of first gonopods beneath flexed pleon. Mature male pleon relatively short, second pleonite of flexed pleon not spanning full width of sternum, small part of eighth sternite mesial to condyle of fifth pereopod coxa exposed, third pleonite completely covering sternum. Mature male first gonopod trunk flattened, twisted along length, broad proximal flange extended posterolaterally over male coxal gonopore and papilla, terminal lips creating wide apical vestibule or semi-enclosed funnel directed somewhat distally or hooked to direct proximally, patch of large subterminal spines directed proximally. Mature female gonopore (= vulva) broadly crescentic to ear-shaped, spanning at least two-thirds of sixth thoracic sternite length.