Platynectes davidorum Hájek, Alarie, Šťastný & Vondráček, 2019

Jiang, Zhuo-Yin, Zhao, Shuang, Jia, Feng-Long & Šťastný, Jaroslav, 2023, Two new species of Platynectes Régimbart, 1879 from China with notes on other Chinese members of the genus, including a key to species (Coleoptera: Dytiscidae: Agabinae), Zootaxa 5227 (4), pp. 401-425 : 406

Platynectes davidorum Hájek, Alarie, Šťastný & Vondráček, 2019

( Figs 2B , 6C–D , 8A , 10A )

Platynectes davidorum Hájek, Alarie, Šťastný & Vondráček, 2019: 221 (orig. descr.).

Type locality. “ China, Fujian Province, Nanping Prefecture, Wuyishan Mts., Tongmu –Sangang vill.”, ca. 27°45.0′N, 117°40.7′E, 720 m.

Type material. Holotype ♂, deposited in IZCAS.

Material studied. CHINA: Jiangxi: 1 ♂, Shangrao, Sanqingshan Mt. , 15-20.iv.2007, F. Jia leg. ( SYSU) ; Zhejiang: 5 ♂, 10 ♀, Quzhou, Qujiang distr., Yaowangshan Mt. , Shennong Waterfall , 28.7632N, 118.9731E, 340 m, 24.viii.2021, Z. Jiang & X. Ye leg. ( SYSU) .

Notes. Habitus and male genitalia are given in Figs 2B and 6C–D .

Collection details. In Yaowangshan Mt. (Zhejiang), Platynectes davidorum was collected during the day under mosses on wet rock, and at night in crevice or surface of rock covered with water film near waterfall ( Fig. 8A ).

Distribution. Eastern China (Fujian, Jiangxi, Zhejiang) ( Fig. 10A ). First record from Jiangxi province.

Notes. Platynectes davidorum seems to be strictly hygropetric, all specimens examined and also the type material ( Hájek et al. 2019) were found in water films on rock surface. The strongly convex body and short appendages of the adults are likely adaptive features associated with this hygropetric lifestyle ( Hájek et al. 2019). Besides this, another hygropetric species Hydrotrupes chinensis Nilsson, 2003 , collected together with P. davidorum in Yaowangshan Mt. (Zhejiang), also displays a strongly convex body and short appendages, and furthermore absence of natatory setae on legs. These characters reflect adaptation to life on wet rock walls and limited ability to swim. Although Hydrotrupes palpalis Sharp, 1882 from North America has been shown capable of swimming ( Hering 1998), individuals of this species often stay on rock surface within water films ( Larson et al. 2000). The presence of natatory setae on the legs of P. davidorum may suggest that this species retains an ability to swim, as has been shown for the well-known North American hygropetric Hydrotrupes palpalis .

Figures

FIGURE 2. Habitus of Platynectes species. (A) P. babai Satô (♂; Kaohsiung, Taiwan); (B) P. davidorum Hájek et al. (♂; Yaowangshan, Zhejiang); (C) P. dissimilis (Sharp) (♂; Dinghushan, Guangdong); (D) P. dissimilis (Sharp) (♂; Yunhe Village, Hunan). Scale bar = 2.0 mm.

FIGURE 6. Male genitalia of Platynectes species. (A, C, E–H, J–N) median lobe in lateral view; (B, D, I, O) paramere. (A–B) P. babai Satô (Kaohsiung, Taiwan); (C–D) P. davidorum Hájek et al. (Yaowangshan, Zhejiang); (E) P. dissimilis (Sharp) (Dinghushan, Guangdong); (F) P. dissimilis (Sharp) (Huaping, Guangxi); (G) P. dissimilis (Sharp) (Yunhe Village, Hunan); (H–I) P. dissimilis (Sharp) (Gutianshan, Zhejiang); (J) P. gemellatus Šťastný (Rongshuao, Hongkong); (K) P. gemellatus Šťastný (Baim- aoping Town, Hunan); (L) P. gemellatus Šťastný (Jinggangshan, Jiangxi); (M) P. gemellatus Šťastný (Gutianshan, Zhejiang); (N–O) P. gemellatus Šťastný (Nanling, Guangdong). Scale bars = 0.5 mm.

FIGURE 8. Habitat of Platynectes species. (A) Yaowangshan, Zhejiang (P. davidorum); (B) Gutianshan, Zhejiang (P. dissimilis & P. gemellatus); (C) Tianpu Village, Zhejiang (P. dissimilis); (D) Liuxihe, Guangdong (P. gemellatus).

FIGURE 10. Maps of distribution of Platynectes species in China. (A) P. babai and P. davidorum; (B) P. dissimilis.