(Rathbun, 1907)
This species differs from Hyastenus kyusyuensis in having five tubercles, which are placed in a transverse row on the anterior surface of the gastric region, one of which occupies the median position and is posteriorly followed by another tubercle. Other remarkable tubercles are: one behind the postocular cup on the hepatic margin, two at outer anterior corner of branchial region and a sharp one at the junction of the antero-lateral and postero-lateral borders.
The entire animal is closely covered with pubescence and the regions are fairly well delimited. The pseudorostral spines are almost half the length of the carapace and are divergent at an angle of about 50°. The preocular spine distinct; the postocular cup has no accessory lobule on the upper inner border. The basal antennal segment has a sharp antero-external tooth and an indistinct one near the proximal end.
All thoracic appendages are thickly covered with tomentum, excepting the fingers, which do not gape at the base. (Sakai, 1938: 283)
Type locality: Funafuti, Tuvalu.
Range: Amirante Islands (Rathbun, 1911); Cargados Carajos (Rathbun, 1911); Japan - Misaki, Tosa Okinoshima and Wakayama (Sakai, 1938a), Sagami Bay, Kii Peninsula and Tosa Bay (Sakai, 1976a), Mage-jima, Kagoshima Prefecture (Takeda, 1977b), Kushimoto (Miyake, 1983), Kakeroma-jima near Amami-Oshima (Takeda, 1989); Indonesia - Flores Sea, Banda Sea and Timor (Griffin & Tranter, 1986a); Torres Strait - Murray Island (Griffin & Tranter, 1986a); Australia - Cape Jaubert (Rathbun, 1924c), Moreton Bay (Campbell & Stephenson, 1970), Eighty Mile Beach, W.A., Moreton Bay, Wistari Reef, Heron Island, Townsville and Lizard Island, Queensland (Griffin & Tranter, 1986a); Tuvalu (Rathbun, 1907); 5-50 m.