Hemilepistus (Desertellio) ruderalis ( Pallas, 1771 )

Wang, Jin, Hong, Xinkai, Jiang, Chao & Li, Weichun, 2023, First record of the subgenus Hemilepistus (Desertellio) (Isopoda, Agnaridae) from China, Zootaxa 5389 (3), pp. 362-372 : 368-370

Hemilepistus (Desertellio) ruderalis ( Pallas, 1771)

Figs 4−5

Material examined: Three males, four females, CHINA: Xinjiang Uygur Autonomous Region, Yining (43°54’N, 81°33’E), an uncultivated land near Road 704 , 14.vii.2021, leg. Sheng Du, prep. slide nos. L21030–21033, L21035– 21037, L21038–21040, accession nos. LC729528–LC729531, LC729535 (deposited in the Insect Museum, Jiangxi Agricultural University, Nanchang, China) .

Redescription: Body thin and long, 3.0 times as long as greatest width. Colour varies among different individuals, including ochre yellow, grey and brown. Head with numerous small tubercles; lateral lobe quadrangular, median lobe small and with or without an incision in middle. Eyes with 24–27 large ommatidia. Pereonites 1 and 2 variated in shape, hind margin rounded or angled; pereonite 1 densely covered with tubercles of various sizes; pereonite 2 scattered with small tubercles, and median part with two or four large tubercles; pereonites 3–7 smooth. Pleon smooth. Telson basally broad, narrowed towards distal tip, lateral margin gently concave near blunted apex.

Antennula composed of three articles, distal article bearing apical set of six small aesthetascs. Antenna thin and long, reaching third pereonite when extended backwards, fifth article of peduncle and flagellum equipped with large setae, flagellum with first segment twice as long as second one.

Pereopods 1 and 7 without sexual dimorphism, merus and carpus equipped with strong spines on sternal and distal margins; pereopod 7 with well-developed spines at distal margin of carpus.

Pleopods 1 and 2 exopodites with well-developed monospiracular internal lungs; pleopods 3–5 exopodites with small lungs, distally convex. Male pleopod 1 endopodite styliform, apical tip with a finger-like inner lobe, bearing a line of small spines on inner margin; male pleopod 2 endopodite thin and long, nearly as long as exopodite.

Uropods protopod with conspicuous incision on lateral margin, exopod long and conical.

Size: 21–29 mm.

Remarks: This species has conspicuous phenotypic plasticity ( Fig. 4 ): the individuals are not only different in the body colour (ochre yellow, grey or brown), but also vary in the hind margins of pereonites 1 and 2 (rounded or angled) and the numbers (four or two) of the large tubercles in the middle of pereonite 2. These different morphological characters have been verified to intraspecific variations by using the partial sequences of COI ( Tab. 1 , Fig. 1 ). This species is reported from China for the first time.

Distribution: China (Xinjiang); Azerbaijan; Crimea; “Caucasus”; Kazakhstan; Kirghizistan; Russia; Turkmenistan.

Figures

FIGURE 1. Bayesian consensus tree based on COI dataset with best ModelFinder model applied. Values above the nodes represent the posterior probability (PP) of the Bayesian analysis, and below the nodes represent bootstrap support (BS) values from 1000 replicates. Phenotype 1: LC729532, phenotype 2: LC729534−729535, phenotype 3: LC729528−729531 (from left to right).

FIGURE 4. Hemilepistus (D.) ruderalis (Pallas, 1771), male. A−D, head (A and B, dorsal view; C and D, frontal view); E−G, head and pereonites 1 and 2 in dorsal view; H−J, pleon in dorsal view. Scale bars: A−D with 1 mm, E−J with 2 mm.

FIGURE 5. Hemilepistus (D.) ruderalis (Pallas, 1771), male. A, antennula; B, antenna; C, pereopod 1; D, pereopod 7; E, pleopod 1 exopodite; F, pleopod 1 endopodite and enlarged apex; G, pleopod 2; H, pleopod 3 exopodite; I, pleopod 4 exopodite; J, pleopod 5 exopodite. Scale bars: 1 mm except for figure A with 0.2 mm.