Caecopilumnus crassipes
Creators: name: Ng, Peter K. L.
name: Rahayu, Dwi Listyo
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pilumnidae
Caecopilumnus
Caecopilumnus crassipes

description: Caecopilumnus crassipes (Tesch, 1918)
(Figs. 1E, F, 4C, D, 5I, 6D, 28–31, 41C)
Typhlocarcinoides crassipes Tesch, 1918: 230, pl. 15 fig. 1.— Balss 1938: 73.— Sakai 1955: 109, text-fig. 5.— Serène 1968: 92.— Sakai 1976: 550, text-fig. 297.
Caecopilumnus crassipes — Ng 1987: 91.— Ng et al. 2008: 143.
Material examined. Holotype: male (7.9 × 6.3 mm) (ZMA 103.006), station 225c, reef, Lucipara I., Banda Sea, Indonesia, coll. SIBOGA Expedition, July 1899.
Others — Indonesia: 1 male (11.8 × 10.1 mm) (ZRC 2013.1710), Kecinan, western Lombok, Lesser Sunda Island, 0824.368'S 11603.561'E, sand with seagrass, 0–1 m, coll. D.L. Rahayu et al., 15 May 2007; 2 males (12.9 × 11.4 mm, 5.5 × 4.2 mm) (ZRC 2013.1711), 1 male (11.1 × 9.5 mm), 1 female (13.0 × 11.0 mm) (MZB Cru 3915), intertidal areas, Sira, northern Lombok, Lesser Sunda Island, 0821.641'S 11606.272'E, coll. D.L. Rahayu et al., 13 June 2007; Japan: 1 male (9.0 × 7.8 mm) (ZRC 2013.0410), Okinawa, Runigami, Yona, coll. T. Maenosono, 17 April 2010; 1 ovigerous female (12.3 × 10.7 mm) (ZRC 2013.0411), Sesoko, Okinawa, coll. T. Maenosono, 7 Jun 2009; 1 female (5.3 × 4.5 mm) (SMF 37785), March 1979.
Diagnosis. Carapace subovate; dorsal surface finely granular; regions separated by relatively shallow grooves (Figs. 28A, 29A, 30). Anterolateral margin arcuate, granular, with low granuliform lobes, sometimes not discernible (Figs. 28A, 29A, 30). Merus of third maxilliped prominently rounded (Figs. 5I, 28B, 31B). Merus of last ambulatory leg 1.5 times as long as broad; propodus ovate, as long as broad (Figs. 28C). Male abdomen relatively narrower; a1 with lateral margins gently convex or subtruncate; a3–6 proportionately narrower (Fig. 31A). Gl stout, gently sinuous, proximally dilated, tip narrow, lateral, mesial margin with row of spinules, outer, inner surface with scattered spinules (Fig. 31D–F). G2 as long as G1; distal segment half length of basal segment (Fig. 31G).
Re-description. Carapace subovate; dorsal surface convex, finely, evenly granular, setose; regions separated by distinct shallow grooves (Figs. 28A, 29A, 30). Front relatively wide, entire, prominently deflexed, margin gently convex (Figs. 28A, 29A, C, 30). Anterolateral margin arcuate, granular, hirsute, with 2 or 3 low, sometimes indistinct lobes which are lined with granules of varying size; barely separated from posterolateral margin (Figs. 28A, 29A, 30). Posterolateral margin almost straight or gently convex, distinctly converging towards posterior carapace margin (Figs. 28A, 29A, 30). Posterior carapace margin gently concave (Figs. 28A, 29A, 30). Epistome narrow, prominently sunken (Fig. 29C). Basal antennal article transversely rectangular, distinctly wider than long; article 3 longer than wide; article 4 distinctly dorsoventrally flattened, twice as long as broad, margins with numerous long plumose setae (Figs. 6D, 31C). Eye immobile, completely filling ovate orbit; short, pear-shaped, tapering to small cornea that has a tiny dot of pigmentation; peduncle stout (Figs. 29C, 31C).
Third maxillipeds relatively short, stout, leaving narrow gap when closed; ischium rectangular, 1.6 times length of merus, with shallow sublateral sulcus; merus rounded, anterolateral angle strongly convex; exopod relatively narrow, reaching to midlength of merus, with long flagellum (Figs. 5I, 28B, 31B).
Chelipeds subequal, long setae on upper, lower margins of chela, carpus, merus; almost entire surface of outer surface of chela covered by large tubercles, short setae; fingers shorter than palm; dactylus curved, cutting edges with distinct teeth, denticles (Figs. 28A, D, E, 29A, E, F, 30).
Ambulatory legs relatively short, third leg longest; dorsal, ventral margins of ambulatory legs fringed with long setae; merus of last leg 1.5 times as long as broad; propodus of fourth leg subovate, narrow distally, becoming wider proximally, as long as broad; dactylus of fourth leg longer than propodus (Figs. 28A, C, 29A, 30).
Male thoracic sternum narrow; st1, 2 completely fused to form triangular plate, st3 separated from st2 by narrow, shallow, suture; st3, 4 fused with only lateral sutures discernible, medially depressed; sutures 4–7 complete, st8 short, separated from st7 by short, shallow suture; penis coxo-sternal, emerging from cx5, under overlapping parts of st7, 8, then entering exposed short groove between st7, 8 towards sterno-abdominal cavity (Figs. 1E, F, 29B). Sterno-abdominal cavity deep; press-button mechanism for holding male abdomen present as small rounded tubercle on posterior third of st5 (Fig. 1F).
Male abdomen with a1 wide, broad, subrectangular, lateral side almost straight, reaching to cx5; a3–5 fused, sutures visible medially, laterally, usually incomplete; a3 expanded laterally to form triangular plate, covering most of penis when closed; a6 rectangular, lateral sides slightly concave; telson triangular, broader than long, tip rounded (Figs. 1E, 29D, 31A).
Gl stout, gently sinuous, proximally dilated, distal half slightly more slender than proximal, tip narrow, subtruncate, lateral, mesial margin with numerous spinules, outer, inner surface with scattered spinules (Fig. 31D– F). G2 as long as G1; distal segment half length of basal segment (Fig. 31G).
Chelipeds of female with relatively larger, denser tubercles on outer surface of chela (Fig. 28D, E). Female abdomen relatively narrow, all somites, telson free (Figs. 4C, 31H); vulvae subovate, with operculum (Fig. 4D).
Colour. In life, specimens from Lombok and Okinawa are dirty white to cream, sometimes with faint patches of light brown or grey on the dorsal surface of the carapace (Fig. 41C).
Remarks. The figure in Tesch (1918: 230, pl. 15 fig. 1) and his description of the anterolateral margin is not accurate. The anterolateral margin was described and figured as almost entire without lobes or notches, but the holotype female actually possesses low but discernible granulated lobes (Fig. 28A).
Tesch (1918: 227) doubted that C. crassipes “has a right of existence” because he only had a female specimen, and could be separated from C. hirsutus by the setae on the front being relatively longer than those laterally, the granules on the carapace being smaller and the grooves more shallow and less distinct, as well as the shorter and more rounded form of the last ambulatory propodus (Tesch 1918: 228, 230–231). Compared to C. hirsutus, the setae on the front of C. crassipes are generally longer than that on the anterolateral margin, but with only two known specimens of C. hirsutus examined, this is a character of doubtful value. The dorsal carapace characters (relatively weaker granulation and less prominent grooves) are useful, being relatively constant in the series of specimens of C. crassipes examined. While it varies somewhat, from the condition seen in the type female and others (e.g., Figs. 28A, 30) to being more granular with somewhat deeper and more prominent grooves (e.g., Fig. 29A), they are invariably weaker than those in C. hirsutus (Figs. 25A, 26A). The form of the ambulatory propodus is reliable, being consistently more ovate and shorter, and easily distinguishes males and females of C. crassipes from congeners (including C. loculatus sp. nov.) (Fig. 28C versus Figs. 25C, 26C, 32A).
The strength of the lobes and degree of granulation on the anterolateral margin of carapace varies somewhat, mainly with size. A small specimen from Lombok (5.5 × 4.2 mm, ZRC 2013.1711) has the three anterolateral lobes relatively more prominent with strong spine-like granules. In the male specimen from Japan (9.0 × 7.8 mm, ZRC 2013.0410), the granules are larger but it does not form very distinct lobes (Fig. 30C), while large specimens from Lombok (female, 13.0 × 11.0 mm, MZB; male, 12.9 × 11.4 mm, ZRC 2013.1711), the lateral margin is almost entire, lined with large and small tubercles, and the carapace appears somewhat longer (Fig. 30B).
We do not have much doubt about the female specimen reported as “ T. crassipes ” by Sakai (1955, 1976) from the Bonin Is. (= Ogasawara Is.) (collection depth not stated). His description and figure agrees well with our material from the Ryukyus in Japan.
Distribution. Lombok and Maluku (Indonesia), and Okinawa and Ogasawara Is. (Japan); intertidal.
description: Published as part of Ng, Peter K. L. & Rahayu, Dwi Listyo, 2014, Revision of the family Acidopsidae Števčić, 2005, and the systematic position of Typhlocarcinodes Alcock, 1900, Caecopilumnus Borradaile, 1902, and Raoulia Ng, 1987, with descriptions of two new genera and five new species (Crustacea: Brachyura: Goneplacoidea), pp. 1-63 in Zootaxa 3773 (1) on pages 42-47, DOI: 10.11646/zootaxa.3773.1.1, http://zenodo.org/record/4909796