Cymonomus java Ahyong, Mitra and Ng, 2020

Islam, Atikul, Banerjee, Abhishek, Wati, Sisca Meida, Banerjee, Sumita, Shrivastava, Deepti & Srivastava, Kumar Chandan, 2022, Crabs (Crustacea, Decapoda) from the Sea off East and Southeast Asia Collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 2. Timor Sea, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (1), pp. 5-24 : 8

Cymonomus java Ahyong, Mitra and Ng, 2020

( Fig. 1C–D )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 26 (Timor Sea; 09°27.0′S, 127°58.6′E — 09°28.5′S, 127°56.1′E, 610–690 m depth), 3 m beam trawl; June 19, 1972; 1 ♀ (NSMT-Cr 29248: CB 7.9 mm, CL 8.1 mm including rostrum).

Remarks. The genus Cymonomus is composed of 32 Indo-West Pacific species (including C. suluensis Takeda, Ohtsuchi and Komatsu, 2021 ), 11 West Atlantic species, and two Northeast Atlantic and Mediterranean species ( Takeda et al., 2021). Ahyong (2019) distinguished six species groups: 1) C. bathamiae group, 2) C. curvirostris group, 3) C. delli group, 4) C. granulatus group, 5) C. karenae group, and 6) C. soela group, and then Takeda et al. (2021) added the C. suluensis group.

The female at hand is referable to the C. delli group, which is represented by the following six species: C. andamanicus Alcock, 1905 ; C. cubensis Chace, 1940 ; C. delli Griffin and Brown, 1976 ; C. diogenes Ahyong and Ng, 2009 ; C. cognatus Ahyong and Ng, 2017 ; C. java Ahyong, Mitra and Ng, 2020 . Among these congeners, the female at hand corresponds most closely to C. java and C. andamanicus . Like C. andamanicus , C. java is known only by a male, so comparisons with the present female of the proportional sizes of the chelipeds and ambulatory legs, and of the pleon require caution. The pereopod 3 merus of male C. andamanicus and C. java is about 1.0 CL ( Ahyong et al., 2020) compared to 0.9 CL in the female—this difference is consistent with sexual dimorphism in Cymonomus , with the proportional length of the pereopod 3 merus of females typically about 10% less than that of males ( Ahyong et al., 2020). The male telson and pleonal somite 6 of C. andamanicus is immovably fused, with an indistinct demarcation ( Ahyong et al., 2020, fig. 2C), but fully demarcated, and slightly movable in C. java ( Ahyong et al., 2020, fig. 4H). In the female at hand, somite 6 and the telson are immovably fused, but a distinct, complete suture is present as in male C. java . Additionally, the finely granular carapace and pereopodal granulation resembles those of C. java , rather than the coarser ornamentation of C. andamanicus (see Ahyong et al., 2020). Thus, we herein refer the present female to C. java .

Distribution. Originally reported from the south of Java (603–686 m), and now from further east in the Timor Sea (610–690 m).

Figures

Fig. 1. A–B: Krangalangia spinosa (Zarenkov), female (NSMT-Cr 29247: CB 5.1mm×CL 4.8mm) from sta. 33 (Off Sahul Shelf, 535–547m depth). C–D: Cymonomus java Ahyong, Mitra and Ng, female (NSMT-Cr 29248: CB 7.9mm×CL 8.1mm) from sta. 26 (Timor Sea, 610–690m depth).