Caecopilumnus hirsutus Borradaile 1902
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 hirsutus

description: Caecopilumnus hirsutus Borradaile, 1902
(Figs. 5H, 24–27)
Caecopilumnus hirsutus Borradaile, 1902: 237.— Ng 1987: 91.— Ng et al. 2008: 143.
Typhlocarcinodes hirsutus — Tesch 1918: 228, pl. 15 fig. 3.— Yokoya 1933: 200.— Serène 1968: 92.— Sakai 1936: 192, pl. 55 fig. 1.— Sakai 1939: 574, pl. 68 fig. 1.— Sakai 1965: 170, pl. 84 fig. 4.— Serène 1968: 92.— Sakai 1976: 550, pl. 194 fig. 3.
Material examined. Holotype: female (8.4 × 7.2 mm) (CUMZ), Haifaro Reef, Fadiffoha, Maldives, J. S. Gardiner, 1900. Others — Indonesia: 1 male (7.1 × 5.6 mm) (ZMA 261027), station 51, Madura Bay, west coast of Flores, 54–90 m, coll. SIBOGA Expedition, July 1899.
Diagnosis. Carapace subquadrate; dorsal surface prominently granular; regions separated by distinct deep grooves (Figs. 24A, 25A, 26A). Anterolateral margin arcuate, granular, with low granuliform lobes, may be indistinct (Figs. 24A, 25A, 26A). Merus of third maxilliped rounded to subovate (Figs. 5H, 24B, 25B). Merus of last ambulatory leg 2.1 times as long as broad; propodus subovate, longer than broad (Figs. 25C, 26C). Male abdomen relatively wide; a1 with lateral margins straight; a3–6 proportionately wide (Fig. 27A). Gl stout, gently curved, proximally dilated, distal half more slender than proximal, tip tapered, with subdistal spinules (Fig. 27B, C). G2 unknown.
Colour. Sakai (1976: pl. 194 fig. 3) figured the species as cream-coloured with several regularly arranged brown spots on its carapace.
Remarks. This rare species remains somewhat enigmatic. The holotype female is in poor condition but its characters essentially agree with the detailed figures and descriptions by Borradaile (1902) (see Fig. 24). As discussed under C. crassipes, the differences in the carapace and ambulatory legs easily separates C. hirsutus from C. crassipes.
We have doubts if the type female (from the Maldives) is conspecific with the present specimen from Flores in the Lesser Sunda Islands. reported by Tesch (1918). Although their carapaces, chelipeds and ambulatory legs are very similar, their third maxillipeds differ. In the type female, the ischium is prominently rounded and the ischium relatively short (Figs. 24B, 25B). In the male from Flores, the merus is more quadrate and the ischium proportionately longer (Fig. 5H). While we have observed some variation in the form of the third maxilliped in C. crassipes, which is represented by a good series of specimens, it is not to the degree observed here. Nevertheless, with only two specimens, we prefer to err on the side of caution and recognise the Flores specimen as belonging to C. hirsutus for the time being. More material may show otherwise. For more comparisons with C. crassipes, see remarks for this species.
We are also uncertain of the identity of the Japanese material identified as “ Typhlocarcinodes hirsutus ” by Yokoya (1933) and Sakai (1936, 1939, 1965, 1976) from Sagami Bay, Izu Peninsula, Tosa Bay, Bungo Strait and the southern part of the Sea of Japan. The figures are rather schematic but if accurate, on the basis of the deeper carapace grooves (highlighted by Sakai in his key and description) and relatively longer ambulatory propodus, their specimens can be referred to Caecopilumnus hirsutus as defined here. These specimens should be examined at a later date to confirm this identification.
We collected a good series of C. crassipes from intertidal areas of Lombok, which is adjacent to the Banda Sea area where the holotype was collected, presumably also from intertidal areas (stated as “reef collection”). We did not, however, collect any C. hirsutus specimens. The specimen of C. hirsutus from Flores was collected by dredging from depths of 54– 90 m. The habitat of the type female of C. hirsutus was not stated; Borradaile’s (1902) brachyuran material including both intertidal as well as dredged material. Interestingly, Sakai (1976: 550) also indicates that his Japanese specimens of C. hirsutus were collected from the “Bottoms of sand, mud or broken shells; depth 35 to 95 metres”.
Distribution. Maldives, Flores (Indonesia) and Japan; subtidal to 95 m.
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 38-41, DOI: 10.11646/zootaxa.3773.1.1, http://zenodo.org/record/4909796