Microtopsis takedai Komai, Ng & Yamada 2012
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chasmocarcinidae
Microtopsis
Microtopsis takedai

description: Microtopsis takedai Komai, Ng & Yamada, 2012
(Figs. 18 A; 27A; 48A, B; 55B; 62A; 80A, B; 81A–F; 88E; 92A)
Microtopsis takedai Komai, Ng & Yamada, 2012: 149, figs. 1‒5 [type localilty: Japan, Ryukyu Is.].
Type material. Holotype male (2.4 × 3.1 mm) (CBM-ZC 10491), Japan, Ryukyu Is, Okinawa, Nago.
Paratype: female (2.8 × 3.4 mm) (CBM-ZC 10492), male and female (ZRC 2012.0146), type locality.
Other material examined. Japan. 1 male (damaged), 1 female (3.6 × 2.7 mm) (ZRC 2012.0146), Awa, Nago, Okinawa, 13 m, scuba diving, Y. Yamada coll., 0 2.01.2011.
Diagnosis. Carapace (Fig. 18 A; Komai et al. 2012: figs. 1; 2A; 2B) subtrapezoidal, 1.2‒1.3 wider than long; front nearly straight; anterolateral margins arcuate, minutely dentate, without distinct lobes or teeth; dorsal surface almost smooth except for minute granules on lateral surfaces. Epistome (Fig. 27 A; Komai et al. 2012: fig. 2C) slightly depressed; posterior margin with widely semicircular median lobe with median fissure, semicircular lateral margins without fissures. Eye peduncle (Fig. 27 A; Komai et al. 2012: fig. 2B) filling orbit, long, mobile; cornea reduced, pigmented. Third maxillipeds (Fig. 80 A; Komai et al. 2012: fig. 3A) not filling buccal cavern when closed; merus subcircular, anteroexternal angle rounded, narrower than ischium; ischium quadrate, widened inner margin, about same length as merus (Fig. 80 A; Komai et al. 2012: 3A). Chelipeds (Figs. 18 A; 48A, B; Komai et al. 2012: figs. 3B, D; 5A, B) subequal in length, slightly dissimilar in female, heteromorphic in males; cutting margins of both chelipeds of females, minor in males with dense row of short setae (Fig. 48 B; Komai et al. 2012: figs. 3D, 5A, B), largest chela of male (Fig. 48 A; Komai et al. 2012: 3B) high, with broad teeth on pollex, dentate dactylus. Inner margin of cheliped carpus (Fig. 18 A; Komai et al. 2012: 3C, E) with short tooth. Ventral surface of cheliped merus with short row of low microscopic tubercles on posterior outer margin in both sexes. Meri of ambulatory legs unarmed; P5 merus 0.5 cl in paratype female. Fused thoracic sternites 1, 2 (Fig. 55 B; Komai et al. 2012: fig. 2D) broadly triangular, proportionally long, short; fused sternites 3, 4 (Figs. 88 E; 92A; Komai et al. 2012: fig. 2E) relatively broad. Male pleon (Figs. 55 B; 62A; 80B; Komai et al. 2012: fig. 2D; 2H) with lateral margins of somite 6, fused somites 3‒5 convex; telson proportionally short; postero-lateral regions slightly swollen. Sterno-pleonal cavity deep. Press-button for pleonal holding (Komai et al. 2012: fig. 2G) as small, short tubercle posterior to thoracic sternal suture 4/5 near edge of sterno-pleonal cavity. G1 (Fig. 81 A‒E; Komai et al. 2012: fig. 4A‒E) stout, short, median part distinctly twisted, distal part slightly twisted, distal segment with short spinules. G2 (Fig. 81 F); Komai et al. 2012: fig. 4F) slightly curved, slender, pointed distal segment, almost as long as G1. Somites of female pleon (Fig. 88 E; Komai et al. 2012: fig. 5D) with convex lateral margins; telson proportionally short. Sterno-pleonal cavity of female (Fig. 92 A; Komai et al. 2012: fig. 5C) moderately deep, vulvae far apart from each other on outer margins of cavity close to suture 5/6.
Remarks. The third maxilliped merus is incorrectly described and illustrated by Komai et al. (2012: fig. 3A). It is not subtriangular, but rather more subcircular, with the anterior margin even rather than distinctly produced. The “supplementary plate” (Fig. 62 A), which is about the same short length along thoracic sternite 8 and reaches episternite 7 in the paratype male (ZRC 2012.0146), is not as narrow and not reaching the posterior edge of the pleon as depicted in the holotype by Komai et al. (2012: fig. 3E).
Distribution. Known only from Japan. Depth: 13 m.
description: Published as part of Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), pp. 1-182 in Zootaxa 4209 (1) on pages 85-86, DOI: 10.11646/zootaxa.4209.1.1, http://zenodo.org/record/272646