Suborder Apseudomorpha Sieg, 1980 Synonym: Monokonophora Lang, 1956 Subfamily Synapseudinae Guţu, 1972 Synonymy. Synapseudidae Guţu sensu Băcescu (1976a). Diagnosis (amended). Body sub-cylindrical; pereonites without apophyses; lateral margins parallel. Pleon short with one to three partially fused pleonites or vestiges thereof. Antennular peduncle with four articles, with or without apophyses, article-1 distinctly longer than articles 2–4 combined, outer flagellum with up to four articles, inner with at least two. Antenna with squama absent, articulation variable, between two to six articles (usually five or six), with or without apophyses, shorter than first peduncle article of antennule. Mandibular palp with article-1 subequal to article-2; articles 1–2 asetose; article-3 with or without terminal setation. Chelipeds without exopod; Pereopod-1 without exopod; coxa lacking apophysis or acute anterior process; basis usually with apophyses or spiniform tubercles on anterior margin, pereopods 2–3 with or without such apophyses. Pereopods 4–6 having dactylus with shallow ventral apophysis. Pleopods absent. Uropod basal article with or without small distomedial apophysis or acute process, rami with exopod having with two to three and endopod having three to four articles. Sexual dimorphism in males, either one cheliped distinctly larger than the other (heterochelate) or both equal (symmetrical), but chelipeds distinctly larger than those of female. Type genus. Synapseudes Miller, 1940. Other genera included. Vicinisyndes Guţu, 2007; Creefs Stępień & Błażewicz-Paszkowycz, 2013. Remarks. Based on our findings, Curtipleon, Cryptapseudes, and the nominal sub-Antarctic species S. idios are no longer accommodated within the Synapseudinae. Cryptapseudes is separated from all the members of this subfamily by having an antennal squama, exopods on the cheliped and pereopod-1, and five pairs of reduced biramous pleopods. These characters are like those in the Metapseudinae and Chondropodinae. Curtipleon is distinguished from genera within the Synapseudinae by (1) lack of a strong spiniform seta on distolateral margins of maxilliped palp articles 1 and 2, (2) cheliped basis in both sexes with several to many strongly developed spines on one or both dorsal and ventral margins, (3) dactylus of pereopod-1 appearing asymmetrically bifurcate, and (4) general presence of numerous subequal spiniform setae along the margins of the pereopods. The systematic status of Cryptapseudes and Curtipleon are currently being evaluated by Jóźwiak (pers. comm. 2016). The presence of pleopods, an antenna with seven articles, a uropodal exopod with three articles, and vestiges of five pleonites in Synapseudes idios indicate that it represents a new genus with affinities to the Metapseudinae as defined and discussed below. Based on the amended diagnosis presented here, the Synapseudinae presently accommodates three genera: Synapseudes and the two monotypic genera, Vicinisyndes and Creefs. Vicinisyndes, except for having a (1) more elongate body, (2) a much narrower chela in female (male unknown), distinct demarcation of the first pleonite, and complete fusion of pleonites 2–5 with the pleotelson, resembles Synapseudes. Creefs superficially resembles Vicinisyndes by having an elongate body, narrow chela in the female, and similar abdominal segmentation; however, Creefs is distinguished from both Synapseudes and Vicinisyndes by a (1) reduced number of articles in the antenna, (2) distinctly narrower and more elongate antennule, (3) expanded propodus on pereopod-1, and (4) uropodal exopod with three rather than two articles.

Published as part of Heard, Richard W., Stępień, Anna, Drumm, David T., Błażewicz, Magdalena & Anderson, Gary, 2018, Systematic and taxonomic observations on the subfamily Synapseudinae Guţu, 1972 and related metapseudid taxa (Crustacea: Tanaidacea: Apseudomorpha), with the erection of a new genus and descriptions of three new species, pp. 301-344 in Zootaxa 4370 (4) on page 307, DOI: 10.11646/zootaxa.4370.4.1, http://zenodo.org/record/1146373