Hemilepistus (H.) conicus, Wang & Hong & Li, 2022

Wang, Jin, Hong, Xinkai & Li, Weichun, 2022, First record of the genus Hemilepistus (Isopoda: Agnaridae) from China, with description of two new species, Zootaxa 5188 (1), pp. 87-94 : 90-93

Hemilepistus (H.) conicus sp. nov.

http://zoobank.org/zoobank.org/ DC67025D-962B-4AC7-B0FB-9033F2B7E453

Figs 3–4

Holotype. Male, CHINA: Xinjiang Uygur Autonomous Region, Yining (43°54’N, 81°33’E), an uncultivated land near Road 704, 14.vii.2021, leg. Du Sheng, prep. slide nos. L21045–21046 . Paratypes. One female, same collection data as holotype.

Diagnosis. Head with three conical tubercles situated in dorsal median of frons ( Fig. 3 A−D). Pereonites 1 and 2 with 12 large conical tubercles near posterior margins, three and four conical tubercles present on lateral areas of tergites 1 and 2, respectively; pereonite 3 with six to seven lateral weak tubercles, posterior margin smooth ( Fig. 3A, B ).

Description. Body length 20 mm. Colour grey, tubercles and epimera white, posterior margin of pereon and pleon slightly lighter. Pereonites 1 and 2 with 12 large conical tubercles near posterior margins, directed upwards on tergite 1 and backwards on tergite 2, and their lateral areas with three and four conical tubercles, respectively; pereonite 3 with six to seven weak tubercles on lateral area, posterior margin smooth; pereonites 4–7 smooth ( Fig. 3A, B ). Pleon short, smooth and narrower than pereon, epimera of pleonite 5 reaching distal one third part of the basipodite ( Fig. 3E ). Telson triangular, approximate twice as wide as long, lateral margin concave at about distal two fifths, apex blunted round; uropodal protopod with conspicuous incision on lateral margin, exopod short and conical ( Fig. 3E ).

Head with three conical tubercles in middle of frons; eyes with 24 large ommatidia, five to six tubercles of various sizes above eye ( Fig. 3C, D ). Antennule composed of three articles, segment 1 approximate as long as segments 2 and 3 ( Fig. 4A ). Antenna reaches posterior part of pereonite 2 when extended backwards, flagellum with first segment slightly longer than second one ( Fig. 4B ).

Pereopods I and VII without sexual dimorphism. Pereopod I with two and three spines on distal tip of merus and carpus respectively, pereopod VII with five and six spines on the distal tip of merus and carpus respectively ( Fig. 4C, D ).

Pleopods, sexual differentiation. Pleopods I and II exopodites with sinuous outer margins, pleopodal lungs well-developed ( Fig. 4E, G ); pleopods III–V exopodites with small lungs ( Fig. 4H–J ). Male pleopod I endopodite with broad basal part, narrowed towards apical tip, apical tip finger-like, equipped with four small spines and a line of tiny thorns ( Fig. 4F ). Male pleopod II endopodite slightly longer exopodite, with distal article long and narrowed apically ( Fig. 4G ). Pleopods III–V exopodites distally angled on inner margin ( Fig. 4H–J ).

Distribution. China (Xinjiang).

Etymology. The specific name is derived from the Latin conicus = conical, in reference to the species that has well-developed conical tubercles on the dorsal surface of the head and pereonites 1 and 2.

Remarks. This new species is similar to Hemilpistus rhinoceros Borutzky, 1958 by pereonites 1 and 2 with conical tubercles directed upwards on tergite 1 and backwards on tergite 2. But it can be distinguished from the latter by the largest tubercle on the dorsal side of the head situated in a lateral position, and pereonite 3 with six to seven tubercles on the lateral area ( Fig. 3A, C ). In H. rhinoceros , the largest tubercle of the head is situated in the median position, and the smooth pereonite 3 without tuberosity ( Lincoln 1970).

Figures

FIGURE 3. Hemilepistus (H.) conicus sp. nov., holotype A, head and pereonites 1−3 in dorsal view; B, head and pereonites 1−3 in lateral view; C, head in frontal view; D, head in dorsal view; E, pleon in dorsal view. Scale bars: 1 mm.

FIGURE 4. Hemilepistus (H.) conicus sp. nov., holotype A, antennula; B, antenna; C, pereopod I; D, pereopod VII; E, pleopod I exopodite; F, pleopod I endopod and enlarged apex; G, pleopod II; H, pleopod III exopodite; I, pleopod IV exopodite; J, pleopod V exopodite. Scale bars: 0.5 mm except for figure A with 0.1 mm.