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 View FIGURE 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.