Lophoplax takakurai Sakai 1935
Creators: name: Ng, Peter K. L.
name: Ahyong
name: Shane T.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pilumnidae
Lophoplax
Lophoplax takakurai

description: Lophoplax takakurai Sakai, 1935a
(Figs. 4, 5)
Lophoplax takakurai Sakai, 1935a: 82, text-fig. 15, pl. 7, fig. 2; Sakai, 1935b: 188, frontispiece, fig. 2; Sakai, 1939: 567, pl. 67, fig. l; Sakai, 1976: 541 pl. 191, fig. 4, text-fig. 288; Ng, 1987: 79, 100; Takeda, 1993: 41; Ng et al., 2008: 143; Takeda & Komatsu, 2018: 176, fig. 7; Takeda & Komatsu, 2023: 167.
Material examined. 1 male (5.0 × 4.2 mm) (NSMT-Cr S 1254), Futami Bay, Chichi-jima [= Island], Ogasawara Islands, Japan, 27°04.77′N 142°11.68′E to 27°04.76′N 142°11.73′E, 42.2– 41.6 m, R / V Koyo, 2010 cruise, station KY-10-25, 9 July 2010.
Diagnosis. Carapace frontal margin gently convex, smooth, produced anteriorly, lateral lobe not visible (Fig. 4A, B); epigastric areole barely visible; protogastric lobe low, with granular surface (Fig. 4B); metabranchial region with low granules (Fig. 4B); median lobe on posterior margin of epistome subtruncate in form (Figs. 4E, 5E). Distal margin of ischium of third maxilliped with row of closely set low granules (Fig. 4C). P2–5 merus extensor margin P2–5 with low proximal tooth (Fig. 5F, G). Cheliped carpus dorsal surface with longitudinal areole separated by groove from swollen lateral margin (Fig. 4A, I); proximal basal part of male chela covered with strong tubercles (Fig. 4G). Male thoracic sternum anteriorly relatively narrower (Fig. 4F). G1 strongly sinuous, distal part of G1 gently recurved (Fig. 5I, J). G2 sigmoid, about ¼ length of G1.
Remarks. Lophoplax takakurai was described on the basis of a female (11.0 × 9.0 mm) collected off Yoshihama, west of Sagami Bay, and later reported from off Mikawa Bay (south of Nagoya) (Sakai, 1935a, b, 1976). Takeda (1993) subsequently recorded the species from Shibushi Bay in Kagoshima, with Takeda & Komatsu (2018, 2023) recording it from the Ogasawara Islands. The whereabouts of the type specimen is not known but appears to be lost. The present specimen matches the type description and figures of Sakai (1935a, 1939, 1976) well, especially in the general carapace features and proportions of the ambulatory legs. Significantly, Sakai (1935a: text-fig. 15c; present Fig. 5B) figured the third maxilliped showing a row of closely set granules on the distal margin of the ischium, a character also distinct in the present male specimen (Fig. 4C). As such, we are confident of its identity. For the moment, L. takakurai, as defined by Takeda & Komatsu (2018) and the present study, is clearly recognisable, so a neotype designation does not appear to be necessary.
Although L. takakurai differs markedly from L. bicristata in many characters of the carapace and pereopods, both species have generally similar carapace shape and features. In addition, both species have a stouter G1 (Figs. 3F–I, 5I, J) compared to more typical pilumnids. It is therefore reasonable to retain both species in Lophoplax for the time being.
Lophoplax takakurai occurs on muddy bottoms 41.6–100 m in depth (Sakai, 1976; Takeda & Komatsu, 2018).
description: Published as part of 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), pp. 335-355 in Raffles Bulletin of Zoology 72 on pages 341-343, DOI: 10.26107/RBZ-2024-0027, http://zenodo.org/record/14682761