Crinitocinus alcocki ( Borradaile, 1902 )

Ng, Peter K. L. & Lin, Chia-Wei, 2023, Two new species of hairy crabs (Pilumnidae) and the first record of Crinitocinus alcocki (Borradaile, 1900) (Acidopsidae) (Crustacea: Brachyura) from Taiwan, Zootaxa 5297 (1), pp. 101-114 : 111

Crinitocinus alcocki ( Borradaile, 1902)

( Figs. 1E, F, H , 8 )

Material examined. 1 male (6.8 × 6.2 mm) ( NMMBCD5628 ), Xiao Liuqiu (= Small Liukiu Island), Pingdong County, Taiwan, coll. SCUBA, C.-W. Lin, 14 October 2020 ; 1 male (9.3 × 7.9 mm) ( ZRC 2022.0825 ), Lutao (= Green Island), Taitung County, Taiwan, coll. SCUBA, C.-W. Lin, 12 May 2022 .

Colour. Ng & Rahayu (2014: 16) described the colour of live specimens as having a white carapace, chelipeds and ambulatory legs, with patches of orange or red. In the two present specimens, the setae are bright orange, with the base of the setae relatively darker in colour; and the fingers are reddish-brown ( Fig. 1E, F ).

Remarks. Ng & Rahayu (2014) redescribed this rare species based on the types and noted that the very wide range of the species (from the Maldives to Hawaii) may suggest we are dealing with more than one species. The limited material they had, however, could not conclusively resolve this. The Indian Ocean specimens (including the types) are juvenile males, while the only male specimen from the Pacific (Hawaii) was badly damaged. The available female specimens do not show major differences, with the authors noting that the carapace of the Pacific specimens is proportionately wider and their eyes relatively smaller ( Ng & Rahayu 2014: 16). The G1 and G2 of the present male specimens from Taiwan ( Fig. 8F–H ) agree well with those from Hawaii figured by Ng & Rahayu (2014).

Biology. The specimens were found in a coral rubble zone, under or adjacent to rocks ( Fig. 1H ).

Distribution. Crinitocinus alcocki has previously been reported from the Maldives and Amirante Islands in the western Indian Ocean; and Papua New Guinea and Hawaii in the western Pacific ( Ng & Rahayu 2014). The present report from southern Taiwan extends its known range northwards.

Figures

FIGURE 1. Colour in life. A, G, Heteropilumnus planus n. sp., holotype male (10.7 × 8.0 mm) (NMMBCD5625); B, H. planus n. sp., paratype female (11.4 × 8.2 mm) (NMMBCD5626); C, H. planus n. sp., paratype female (10.5 × 7.9 mm) (ZRC 2017.1044); D, Pseudolitochira taiwang n. sp., holotype female (11.2 × 8.1 mm) (NMMBCD5627); E, Crinitocinus alcocki (Borradaile, 1902), male (9.3 × 7.9 mm) (ZRC 2022.0825); F, H, C. alcocki (Borradaile, 1902), male (6.8 × 6.2 mm) (NMMBCD5628). G, H, in situ in habitat; H at night with filter. All specimens from Taiwan.

FIGURE 8. Crinitocinus alcocki (Borradaile, 1902), male (9.3 × 7.9 mm) (ZRC 2022.0825), Taiwan.A, overall dorsal habitus; B, left third maxilliped; C, antennules, antennae, orbits and epistome; D, anterior thoracic sternum, pleonal somites 5, 6 and telson; E, posterior thoracic sternum and pleonal somites 1–4; F, left G1 (ventral view); G, left G1 (dorsal view); H, left G2.