Scaptognathus Trouessart 1889

Genus Scaptognathus Trouessart, 1889

Type: Scaptognathus tridens Trouessart, 1889

Diagnosis. Idiosoma flattened. AD and PD large, OC small. AD, OC, and PD each with pair of Glps. Dorsum with 7, rarely 6 pairs of setae. Adanal setae absent. AE with 3 pairs of setae. PE with 1 dorsal and 3 ventral setae. GA uniform, bipartite, or tripartite, consisting of a membranous “pars membranosum” and a sclerotized “pars sclerosum” (Newell 1984). GA with Pgs and Sgs. Gnathosoma large. Rostrum with wide and truncate apex. Gnathosoma base without maxillary setae. Palpi 2-segmented (P-2, P-3, and P-4 fused into a single segment, but a border line between P-2 and P-3 rarely recognizable), separated from each other by less than width of P-1. P-2 with 2 large spurs on apical portion. Legs slender. Gn shorter than adjoining segment. Lc I–IV crescent-like, without comb. The general structures of the genus is schematically shown in Fig. 7.

Remarks. The genus is distinctive in having relatively large gnathosoma with a spatula-like widened rostral tip. The genus is marine arenicolous and almost cosmopolitan in distribuion.

References. Bartsch (2006b, 2009b), Newell (1984), Trouessart (1889a).

S captognathus arenarius Bartsch, 2007

Diagnosis. Glp-1 posterior to Ds-1. Ds-2 on membranous cuticle. PE with 1 dorsal seta. GA bipartite in female and male. Female with 6 Pgs and 4 Sgs. Male with 12–14 Pgs and 4 Sgs. Tr I–IV with 1-1-1-1 setae; Bf I–IV with 1-1-1-1 setae; Tf I–IV with 6-5-2-(2,3) setae, 1-0-0-0 Bp setae; Gn I–IV with 7-4-2-3 setae, 2-1-0-0 Bp setae; Tb I–IV with 8-5-(5,6)-6 setae, 5-2-(2,3)-3 Bp setae; Ta I–IV with 3-3-3-3 dorsal setae, 1-1-0-0 Bp setae. Lc I with unidentate accessory process. Idiosoma length 246–278 in female, 240–266 (holotype 260) in male, 113 in LV. Idiosoma width 165 in male (holotype). Gnathosoma length 187 in male (holotype), 190–200 in female, 100 in LV. Gnathosoma width 88 in male (holotype). Ratio of gnathosoma to idiosoma 0.72 in male (holotype).

Remarks. This species is characterized by the combination of the large OC, bipartite GA in the male and female, and Tb I with 5 Bp setae. Male, female and LV are known.

Habitat. Littoral zone: Medium-sorted sediment below low water line.

Distribution. Indian Ocean: Duke of Orleans Bay, Esperance (Western Australia) [Australia].

Reference. Bartsch (2007a).

Depository. WAMP.