Rhyscotus subrisus Li & Jiang, sp. nov., representing a new record family Rhyscotidae from China (Isopoda: Oniscidea) Author Yao, Chonghui Author Jiang, Chao Author Li, Weichun text Zoological Systematics 2024 49 2 181 183 http://zoobank.org/5fb03411-a88d-4dfd-9253-41b59cd2d1e1 journal article 10.11865/zs.2024206 2095-6827 12172203 5FB03411-A88D-4DFD-9253-41B59CD2D1E1 Rhyscotus subrisus Li & Jiang , sp. nov. ( Figs 1–2 ) Type material. Holotype ♂ , China : Hainan , Sanya , Jiyang ( 109°34′E , 18°17′N ), elev. 10 m , 9.II.2023 , leg. Haocong Yang ( JXAUM ) . Paratypes . 1♀ , same data as the holotype ; 2♂ 2♀ , same data as the holotype except for collected date 9. VI. 2023 , leg. Chao Jiang ( CMMI ) . Etymology. The specific name is derived from the Latin subrisus = smile, in reference to the dorsal surface of the species with a pattern like a smiling face on the first and second pleonites. Diagnosis. Pleopod 1 endopodite almost three times as long as the longest part of exopodite, and male pleopod 2 exopodite with a finger-shaped apical tip. Description. Body length 5.0–7.0 mm. Colour of dorsal surface white with brown blotches. Each pereonite with two triangular blotches and two incurved stipes near lateral side ( Figs 1A–B ). Pleon narrower than pereon, epimera short; pleonites 1 and 2 with smiling face pattern near middle ( Fig. 1D ). Telson nearly triangular, distinctively concave on lateral margin, distal apex pointed ( Fig. 1D ). Head white with irregular brown patterns; frons brown, bearing fourteen white stripes and three white dots ( Figs 1A− C ). Antenna with second flagellar article almost three times as long as first one, apical organ thin and short ( Fig. 2A ). Pereopods without apparent sexual specializations, pereopod 1 without particular modifications, ischium of pereopod 7 deeply concave on ventral margin ( Figs 2B–C ). Figure 1. Habitus of Rhyscotus subrisus Li & Jiang , sp. nov. , holotype. A. Dorsal view. B. Lateral view. C. Head in frontal view. D. Pleon in dorsal view. E. Pleon in ventral view. Scale bars: A–B = 1.0 mm; C–E = 0.5 mm. Figure 2. Appendages of Rhyscotus subrisus Li & Jiang , sp. nov. , holotype. A. Antenna. B. Pereopod 1. C. Pereopod 7. D. Pleopod 1. E. Pleopod 2. F. Pleopod 3 exopodite. G. Pleopod 4 exopodite. H. Pleopod 5 exopodite. Scale bars = 0.1 mm. Pleopods, sexual differentiation. Male pleopod 1 exopodite small and elliptic; endopodite approximate three times as long as longest part of exopodite, basal part broad, narrowed towards apical tip ( Fig. 2D ). Male pleopod 2 exopodite convex on outer margin, apical tip finger-shaped; endopodite thin and long, distinctly longer than exopodite ( Fig. 2E ). Pleopods 3 and 4 exopodites convex on outer margin, ending with triangular apical tip ( Figs 2F–G ). Pleopod 5 nearly straight on outer margin, concave at distal one-fifth area ( Fig. 2H ). Distribution. China ( Hainan ). Remarks. The new species is similar to R. rotundatus Schmalfuss & Ferrara, 1978 by pointed apex of telson and small and elliptic pleopod 1 exopodite ( Figs 1D , 2D vs. Schmalfuss & Ferrara, 1978: figs 22, 26). But it can be distinguished from the latter species by the features of pleopods 1 and 2: pleopod 1 endopodite of the new species almost three times as long as the longest part of exopodite, and male pleopod 2 exopodite with a finger-shaped apical tip ( Figs 2D, E ); in R. rotundatus , the pleopod 1 endopodite about twice as long as the longest part of exopodite, and the male pleopod 2 exopodite with a round apical tip (Schmalfuss & Ferrara, 1978: figs 26−28). Funding This study was supported by the National Natural Science Foundation of China (31960100, 82073972). Acknowledgements We are grateful to Mr. Haocong Yang for providing the specimens. Special thanks are given to Dr. Ghasem M. Kashani (University of Zanjan , Iran ) and an anonymous reviewer for their insightful suggestions. Chonghui Yao1, Chao Jiang2 *, Weichun Li1 * 1College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China 2 State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China * Corresponding authors, E-mails: jiangchao0411@126.com, weichunlee@126.com