Benthesicymus laciniatus Rathbun, 1906

Yang, Chien-Hui & Chan, Tin-Yam, 2019, New records of Benthesicymus Bate, 1881 (Dendrobranchiata, Penaeoidea, Benthesicymidae) from the abyssal depths of Taiwan, ZooKeys 838, pp. 1-8 : 4-5

Benthesicymus laciniatus Rathbun, 1906 Fig. 3

Benthesicymus laciniatus Rathbun 1906: 906, fig. 59, pl. 19 fig. 3 (type locality: vicinity of Kauai Island, Hawaii); Burkenroad 1936: 26, fig. 1; Crosnier 1986: 851, figs. 6c, 7a-c, 8a-e; Kikuchi and Nemoto 1991: 65.

Benthesicymus Hjorti Sund 1920: 30, fig. 48, pl. 11 fig. 4 (type locality: south of Canary Islands).

Gennadas pectinatus Schmitt 1921: 25, fig. 12, pl. 11 fig. 1 (type locality: off Santa Catalina Island, California).

Material examined.

Taiwan, "TAIWAN 2006", stn CP366, 22°02.87'N, 121°10.08'E, 1302-1301 m, 24 Aug 2006, 1 male cl 14.3 mm (NTOU M02190); stn CP369, 24°18.96'N, 122°04.20'E, 3030-3070 m, 25 Aug 2006, 1 male cl 25.0 mm (NTOU M02191).

Description.

Integument moderately rigid. Rostrum rather straight, armed with two dorsal teeth. Carapace with surface rather smooth, lacking hepatic spine and without distinct grooves or carinae (Fig. 3A). Abdomen with fourth to sixth somites each armed with a distinct posteromedian spine; fourth tergite also with posterior margin distinctly crenate or serrated, bearing 17-19 sharp teeth that progressively become smaller laterally (Fig. 3B). Telson with three pairs of movable lateral spines and one pair of terminal spines, distalmost pair of lateral spines at some distance from terminal spines (Fig. 3C). No spine on both merus and ischium of third maxilliped and first pereiopod. Third maxilliped heavily setose and distal segment lacking spine (Fig. 3D). Petasma generally flat and simple, bilobed (Fig. 3E), distal margin of median lobe slightly serrated (Fig. 3F).

Coloration.

Unknown.

Distribution.

Worldwide distribution and reported from eastern Atlantic, eastern Pacific and Indo-West Pacific, at depths of approximately 1,325-4,000 m but generally from 1,500-3,000 m ( Crosnier 1986).

Remarks.

Benthesicymus laciniatus is recorded from Taiwan for the first time. As mentioned by Kim et al. (2000), B. laciniatus generally inhabits shallower waters than B. crenatus and only sometimes occurs in the abyssal zone. The two Taiwanese specimens have been collected from depths of 3,030-3,070 m and 1,301-1,302 m respectively. In Benthesicymus only two species have the posterior margin of the fourth abdominal tergite crenate (see Burkenroad 1936, Crosnier 1986). The distinguishing characters of these two species are given in the “Remarks” of B. crenatus .

The present two males collected from Taiwan generally agree with previous descriptions of the species except for the petasma with the distal margin of the median lobe not distinctly serrated (see Burkenroad 1936: fig. 1, Crosnier 1986: fig. 8a, b, e). Such difference may be due to the present males are much smaller (cl 14.3-25.0 mm vs. cl 33-36 mm for Burkenroad 1936: fig. 1; Crosnier 1986: fig. 8a, b, e) and probably juveniles.