Thor singularis, Xu & Li, 2015

Xu, Peng & Li, Xin-Zheng, 2015, Report on the Hippolytidae Bate (sensu lato) from China seas, Zoological Systematics 40 (2), pp. 107-165 : 161-162

Thor singularis sp. nov. ( Fig. 35 )

Material examined. Holotype, ovigerous female, MBM136568 , cl 1.94 mm, intertidal, Sanya, Hainan Island, 4 March, 1997, coll. Xin-Zheng Li.

Description. Rostrum short, about half length of carapace; dorsal margin with 3 teeth; ventral margin with only 1 tooth. Carapace with moderately developed antennal tooth and minute pterygostomian tooth.

Pleurae of fourth and fifth abdominal somites each with small posteroventral tooth. Sixth somite 1.8 times as long as fifth mid-dorsal length. Telson about 1.3 times longer than sixth abdominal somite; dorsal surface with 4 pairs of dorsolateral spines and 3 pairs of terminal spines.

Antennular peduncle slightly overreaching midpoint of antennal scale; basal segment longer than distal 2 segments combined; second segment with acute distolateral spine; third segment of antennular peduncle with subtriangular dorsal scale; stylocerite reaching distal end of third segment, armed with little indistinct tooth near proximal end of lateral margin. Antennal scale 2.2 times as long as wide; lateral margin straight, with distolateral tooth exceeded by lamina. Antennal peduncle with basicerite bearing strong distal, ventrolateral tooth; carpocerite overreaching second segment of antennular peduncle.

Third maxilliped with exopod; overreaching distal margin of antennal scale by 1/3 of ultimate segment, which with 6–8 corneous spines distally; ultimate segment subequal in length to antepenultimate segment. First and second pereopods with strap-like, terminally hooked epipods.

First pereopod stout, reaching near to midpoint of antennal scale; dactylus about 0.4 times as long as palm; carpus about 0.7 times as long as chela; merus slightly longer than carpus.

Carpus of second pereopod subdivided into 6 articles, of which proximal third one longest; dactylus about 0.7 times © Zoological Systematics, 40 (2): 107–165 as long as palm; ischium slightly shorter than merus.

Third pereopod overreaching distal margin of antennal scale by dactylus; flexor margin of biunguiculate dactylus with 3 spinules; flexor magin of propodus with 2 rows of 14 or 15 spinules; merus with 2 distolateral spines, slightly shorter than propodus. Fourth pereopod and fifth pereopod in similar structure with third pereopod; merus with only 1 distolateral spine.

Distribution. Only known from the intertidal zone of Hainan Island.

Etymology. The Latin “ singularis ”, single, prefers the single type specimen.

Remarks. The new species shares many morphological characters with Thor hainanensis Xu & Li, 2014 . It can be dinstingershed from the later by first 2 pereopods with epipods. In fact, the epipods on the first two pereopods can differentiate from the other members of the genus Thor . The existence of epipod among different pereopods is considered to be fixed at interspecific level and all the described species of this genus lack the epipod on the second pereopod. Holthuis (1993) used the epipod to distinguish the Thor Kingsley, 1878 and Thoralus Holthuis, 1947 . Thoralus was treated as a junior synonym of Eualus Thallwitz, 1892 . Thor is differentiated from Eualus distinctly by the third segment of antennular peduncle with subtriangular dorsal scale, in Eualus , the third segment of antennular peduncle lacks the subtriangular dorsal scale.

Funding This study was supported by the National Natural Science Foundation of China (41376163), the National Basic Research Program of China (973 Program) (No. 2011 CB 403605), the Special Fund for strategic pilot technology of Chinese Academy of Sciences (A) ( XDA 11020303), the project of the S & T basic work from the Ministry of Science and Technology of China (2014 FY 110500) and the IOCAS (2012 IO 060105).

Figures

Fig. 35. Thor singularis sp. nov. A. Carapace and cephalic appendages, lateral view; B. Abdominal pleurae, lateral view; C. Rostrum, lateral view; D. Third maxilliped, lateral view; E. First pereopod, lateral view; F. Second pereopod, lateral view; G. Third pereopod, lateral view; H. Telson, dorsal view; I. Antennal scale, dorsal view; J. Antennule, dorsal view. Scale bars=1 mm.