Dasygyiinae Holmes 1900
Creators: name: Guinot, Danièle
name: Bakel, Barry Van
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Inachoididae

description: Subfamily Dasygyiinae Holmes, 1900
Dasygyinae Holmes 1900: 27.
Type genus. Dasygyius Rathbun, 1897, replaced by 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 and 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, somites 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. Pleonal-locking mechanism: marked, often pointed button on sternite 5, near suture 5/6; socket on pleotelson (Guinot & Richer de Forges 1997: fig. 14B, C).
Remarks. Based on the analysis of larval characters, Marques & Pohle (1998) considered Paradasygyius (depressus) an inachine, as the sister taxon of Inachus Weber, 1795. Pohle & Marques (2000) found no larval evidence to support the monophyly of Inachoidinae, and Marques & Pohle (2003: 77) were unable to provide a single synapomorphy for the Inachoididae, “with the clade (Anasimus (Paradasygyius (Collodes + Pyromaia )))” supported by some larval characters. See above The family Inachoididae.
Other included genera. None.
description: Published as part of Guinot, Danièle & Bakel, Barry Van, 2020, Extraordinary majoid crabs: the genus Esopus A. Milne-Edwards, 1875 in the new subfamily Esopinae subfam. nov., and erection of Paulitinae subfam. nov. (Crustacea, Decapoda, Brachyura, Majoidea, Inachoididae Dana, 1851), pp. 101-127 in Zootaxa 4766 (1) on page 114, DOI: 10.11646/zootaxa.4766.1.5, http://zenodo.org/record/3763991