Nephropsis serrata Macpherson, 1993

Chang, Su-Ching & Chan, Tin-Yam, 2019, On the clawed lobsters of the genus Nephropsis Wood-Mason, 1872 recently collected from deep-sea cruises off Taiwan and the South China Sea (Crustacea, Decapoda, Nephropidae), ZooKeys 833, pp. 41-58 : 41

Nephropsis serrata Macpherson, 1993 Figs 2A, B, 6

Nephropsis serrata Macpherson, 1993: 59, figs 4-6 (type locality: northwestern Australia); Chan 1997: 414; 2010: 157; Poore 2004: 166, fig. 42b.

Nephropsis hamadai Watabe & Ikeda, 1994: 102, figs 1-2 (type locality: Japan).

Nephropsis lyra Zarenkov, 2006: 87, figs 8-11 (type locality: off northwestern Australia).

Nephropsis pseudoserrata Zarenkov, 2006: 91, figs 15-18 (type locality: northeastern Sumatra).

Material examined.

TAIWAN 2003, stn CD210, 24°28.99'N, 122°12.79'E, 500-1183 m, 1 Jun 2003, 3 females cl 9.6-17.3 mm (NTOU M02156); stn CP214, 24°28.59'N, 122°12.66'E, 490-1027 m, 27 Aug 2003, 6 females cl 12.2-23.4 mm, 1 ovig. female cl 18.4 mm, 2 males cl 14.1, 22.5 mm (NTOU M02157); 3 females cl 17.7-20.5 mm, 1 ovig. female cl 17.9 mm (NTOU M00157); 3 females cl 10.7-25.3 mm, 2 ovig. females cl 19.7, 20.1 mm, 5 males cl 9.7-20.7 mm (NTOU M02150). TAIWAN 2006, stn CP371, 24°28.521'N, 122°12.821'E, 582-613 m, 26 Aug 2006, 1 female cl 12.9 mm (NTOU M02151); 1 female cl 13.7 mm, 1 ovig. female cl 17.7 mm, 1 male cl 16.9 mm (NTOU M02154). TAIWAN 2012, stn CP463, 24°28.775'N, 122°12.719'E, 474-647 m, 30 Jun 2012, 2 females cl 11.8, 21.7 mm, 1 ovig. female cl 18.1 mm, 1 male with damaged carapace (NTOU M02152); 1 male cl 10.6 mm (NTOU M02153); 4 females cl 15.6-21.2 mm, 2 ovig. females cl 18.4, 21.7 mm, 3 males cl 13.1-20.3 mm (NTOU M02155).

Diagnosis.

Carapace slightly granulate. Rostrum 0.4-0.8 times carapace length, with pair of lateral spines. Median groove reaching lateral rostral spines. Each subdorsal carinae with 2-6 distinct spines and some granules. Supraorbital spine well-developed, without post-supraorbital spine. Postcervical groove passing midline of carapace. Distance between orbital margin and postcervical groove 1.5-1.9 times distance between postcervical groove and posterior margin of carapace.

Abdominal tergites smooth, sometimes with some granules on large specimens, without median dorsal carina. Anterior margins of pleura II–V without spines, usually ending in a long, acute point. Uropodal exopod with complete diaeresis.

Cheliped I sparsely granulated, covered with dense hairs. Carpus with anterodorsal spine, 0-1 spine (rarely 0) on inner dorsal border at midlength, and an anteroventral spine on inner margin. Carpus of pereiopod II more or less as long as palm. Carpus of pereiopod III 0.6 times palm length. Dactyli of pereiopods IV and V 0.5-0.6 times propodus length.

Color in life.

Body generally whitish with rostrum, distal parts of pereiopods, maxilliped III, antennular and antennal flagella, abdominal pleura, uropods and distal part of telson pinkish red to reddish. Eyes whitish. Eggs greyish yellow.

Distribution.

Recorded from Indonesia, Australia, Japan, and now Taiwan, at depths of 390-1430 m ( Macpherson 1993; Watabe and Ikeda 1994; Chan 1997; Poore 2004; Zarenkov 2006).

Remarks.

One of the specimens from the lot NTOU M00157 was used and listed in a recent molecular phylogenetic work ( Tshudy et al. 2009: table 1), which is the first literature record of this species from Taiwan. Nephropsis serrata is very similar to N. stewarti . They both lack median dorsal carina on the abdomen and mainly differ in the presence or absence of spines on the subdorsal carina ( Macpherson 1993). The other distinguishing characters mentioned by Macpherson (1993), such as N. serrata having more elongate lateral rostral spines than supraorbital spines, a slightly shorter rostrum, and a less elongate large chela, are difficult to use (see Macpherson 1993: Figs 7, 8). The Taiwanese specimens all bear distinct spines on the subdorsal carinae and agree well with the original description of the species ( Macpherson 1993), except for the carpus of the large cheliped bearing 0-1 (mostly one) rather than two spines on the inner dorsal border at mid-length. Moreover, an ovigerous female (NTOU M02154) is abnormal in having two spines on the right side of the rostrum.

Three recently described species, namely N. hamadai Watabe & Ikeda, 1994, N. lyra Zarenkov, 2006, and N. pseudoserrata Zarenkov, 2006, are treated under the synonyms of N. serrata by Chan (1997, 2010). Some of the differences between N. hamadai and N. serrata proposed by Watabe and Ikeda (1994) have been shown to be inappropriate by Chan (1997). The present Taiwanese material also reflects such an opinion, except for the inner dorsal border of the carpus of the large cheliped always being armed with fewer than two spines at the mid-length (two spines in N serrata by Macpherson 1993 and one spine in N. hamadai by Watabe and Ikeda 1994). In the original description of N. lyra , Zarenkov (2006) argued that this species is closest to N. stewarti and N. grandis Zarenkov 2006. However, N. lyra is actually most similar to N. serrata in bearing 3-4 distinct spines on the subdorsal carina. Since no distinct difference is observed between the original illustrations of N. lyra ( Zarenkov 2006: figs 8-11) from N. serrata , and the type localities of both species are from the same area (i.e., off northwestern Australia), these two species are considered as synonyms pending more evidence to support their separation. Another species, N. pseudoserrata described by Zarenkov (2006), based on a single specimen from Sumatra, is also closest to N. serrata in having 1-2 spines on the subdorsal carina. However, Zarenkov (2006) claimed that N. serrata differs from N. pseudoserrata in the subdorsal carina being smooth. As this separation is based on a misinterpretation and the other differences proposed by Zarenkov (2006: table 4) on the armature of the large cheliped are rather variable in this genus, N. pseudoserrata is not recognized as a species distinct from N. serrata .