Hosekia, Ng & Ahyong & Shane T., 2024

Ng, Peter K. L., Ahyong, & Shane T., 2024, Redefining Lophoplax Tesch, 1918: recognising Myopilumnus Deb, 1989, and the establishment of three new genera, Hosekia, Takedaplax, and Striacoeloma (Crustacea: Brachyura: Pilumnidae), Raffles Bulletin of Zoology 72, pp. 335-355 : 344

Hosekia , new genus

Pseudocryptocoeloma — Edmondson, 1915: 233 (part). (Not Pseudocryptocoeloma Ward, 1936 ).

Lophoplax — Takeda & Kurata, 1984: 201 (part); Takeda & Marumura, 1995: 90 (part); Trivedi et al., 2022: 595 (part); Poore & Ahyong, 2023: 667, 670, 680 (part), fig. 14.112i; Ng & Rahayu, 2023: 429 (part). (Not Lophoplax Tesch, 1918 ).

Type species. Pseudocryptocoeloma symmetrinuda Edmondson, 1951 , by present designation. Gender of genus feminine.

Included species. Only Hosekia symmetrinuda ( Edmondson, 1951) .

Diagnosis. Carapace transversely ovate-subhexagonal; epigastric, protogastric, hepatic, cardiac and intestinal areoles glabrous, prominent, smooth; intestino-branchial areole large, transversely ovate; posterior carapace margin cristate, adjacent to large intestino-branchial areole forming transverse groove extending to edge but not reaching sub-branchial region; orbit clearly visible in dorsal view, supraorbital margin breaking general carapace outline, forming distinct concavity; eyes freely movable; ocular peduncle relatively long; lateral lobe of frontal margin not visible; anterolateral margin with 3 distinct teeth or lobes (including external orbital tooth), without additional lobe or small tubercle posteriorly; without lobe or tubercle at junction between antero- and posterolateral margins; posterolateral margins distinctly converging towards posterior carapace margin. Epistome with median lobe of posterior margin obtusely triangular. Endostome not obliquely recessed posteriorly into buccal cavern, subparallel to adjacent pterygostomial surface; endostomial ridges short. Third maxilliped ischium short, quadrate, length 1.2× width. Adult male chelipeds symmetrical or almost so, stout, outer surface of chela densely covered with granules. Ambulatory legs short, P4 longest, about 1.2× carapace width; merus wide, stout, extensor margin bluntly rounded, surface without medio-longitudinal swelling; P4 merus length about 2.2–2.4× height, less than half carapace width. G1 strongly sinuous, distally gently curved outwards, not hooked.

Etymology. The name is derived from the Japanese word “hoseki” for jewel. Marumura & Takeda (2012: fig. 2A) and Maenosono (2019: fig. 8B) figured the beautiful bright red jewel-like epigastric, protogastric, and hepatic areoles of the type species, to which the genus name alludes. The gender of the genus is feminine.

Remarks. Ng & Rahayu (2023: 430) argued that among the species of Lophoplax , L. symmetrinuda was distinctive and in a group of its own because of its transversely ovate carapace, large expansive areoles, low anterolateral teeth, and smooth posterolateral margin. Our re-examination of the material reinforces their suspicions, and confirms that the species should be referred to its own genus.