Paradasygyiinae

Guinot, Danièle & Van Bakel, Barry W. M., 2020, Diagnosis of the inachoidid subfamily Paradasygyiinae subfam. nov. (Crustacea, Decapoda, Brachyura, Majoidea), Zootaxa 4801 (1), pp. 198-200 : 199

Paradasygyiinae subfam. nov.

Dasygyiinae Guinot & Van Bakel 2020: 114 (not Dasygyinae [sic] Holmes, 1900: 27).

Type genus. Paradasygyius Garth, 1958 (type species by original designation: Microrhynchus depressus Bell, 1835 , now Paradasygyius depressus ).

Description. Body markedly flattened. Carapace rounded, longer as wide, distinctly narrowing anteriorly ( Garth 1958: pl. 4, fig. 2). Carapace resting on setting gutter ( Drach & Guinot 1982: pl. 1, fig. 5). Carapace dorsal surface covered with fine granulations and some occasional larger ones, with shallow grooves ( Santana 2008: figs. 49A, 50A). Rostrum simple, short, as narrow triangle. Preorbital tooth absent. Postorbital tooth large, curving around eye, forming postocular cup (supraocular eave) accommodating eyestalk in resting position ( Santana 2008: fig. 49A, B). Eyes large, flattened. Antenna: basal article adjacent to urinary article, long: with two teeth on inner margin, outer angle conspicuously projecting dorsally by long, narrow tooth; antennal movable portion entirely visible in dorsal view at side of rostrum ( Santana 2008: figs. 49A, 50A). Proepistome laterally compressed, forming slightly recessed septum not joining rudimentary epistome. Branchiostegite very reduced; branchial chamber reduced to narrow space due to flattening of body, probably not functional posteriorly, without gills at level of last pereiopods. Mxp3: ischium narrow, crista dentata formed by triangular teeth; merus narrow at base, then strongly cordiform; coxa short, prolonged by distal lobe to embayment ( Rathbun 1925: fig. 50, as Dasygyius depressus ; Guinot & Richer de Forges 1997: fig. 14A). Thoracic sternum flat, except the first three inflated sternites ( Santana 2008: fig. 49B; Guinot 2012: fig. 3C; Guinot et al. 2019: fig. 16B). Absence of sternum/pterygostome junction, sternite 4 not laterally extended; suture 3/4 short, only lateral, forming deep pocket ( Guinot 2012: fig. 3C, D); Milne-Edwards openings not separated from chelipeds. Presence of very wide sternal extensions joining exposed pleurites (sternum/pleurites connections) between P1/P2, P2/P3, P3/P4, P4/P5. Pleurites regularly connecting medially and fused to carapace by pillars ( Drach & Guinot 1982). Pleurites 5–8 exposed, rather wide, each sclerite pointed at each end, covered with small granules ( Drach & Guinot 1982: pl. 1, fig. 5; Hendrickx 1999: fig. 2A, B; Santana 2008: figs. 49A, 50A). Male chelipeds stout; palm inflated, subglobular; fingers narrowly gaping at base, crenulate on prehensile margins ( Rathbun 1925: fig. 51, as Dasygyius depressus ; Garth 1958: pl. 4, fig. 2; Hendrickx 1999: fig.40B). Female chelipeds weaker than legs, palm not swollen ( Rathbun 1925: pl. 274, figs. 7–8, as Dasygyius depressus ). Ambulatory legs very long, granulate and hairy ( Hendrickx 1999: fig. 40A; Santana 2008: fig. 47B). Pleon: first somite dorsal, granular, produced into long, conical, acute spine in both sexes ( Drach & Guinot 1982: pl. 1, fig. 4; Santana 2008: fig. 50B). Male pleon with somites 1–5 free, somite 6 being fused to telson (pleotelson); female pleon ( Rathbun 1925: pl. 274, fig. 5, as Dasygyius depressus ) with somites 1–4 free, somites 5, 6 being fused to telson (pleotelson). Male gonopore partially condylar, partially coxal ( Guinot et al. 2013: 127). G1 straight, without developed lobe, aperture subapical ( Garth 1958: pl. E, fig. 5). Vulvae located on anteriorly displaced sternite 6, as expansions projecting on sternites 5 and even 4. Pleonallocking mechanism marked: often pointed button on sternite 5, near suture 5/6; socket on pleotelson ( Guinot & Richer de Forges 1997: fig. 14B, C).