Seven new species of hygropetric beetle Satonius Endrödy-Younga 1997 (Myxophaga: Torridincolidae) from China

NEWS - Seven new species were described: Zaixiong Chen hygropetric beetle (Satonius cheni sp. nov.), black belly hygropetric beetle (Satonius nigriventralis sp. nov.), Hong Pang hygropetric beetle (Satonius panghongae sp. nov.), Quzhou hygropetric beetle (Satonius quzhouensis sp. nov.), Xinhui hygropetric beetle (Satonius xinhuiensis sp. nov.), Youxiang Zhang hygropetric beetle (Satonius zhangi sp. nov.) and Zhenhua Liu hygropetric beetle (Satonius zhenhuai sp. nov.).

Torridincolidae is a family of water beetles in the suborder Myxophaga comprising 54 species in 7 genera. Torridincolids are known from Central and Southern Africa, Madagascar, Central and Northern South America, Japan and China. They mostly live in seasonal mountain streams, hygropetricular habitats or spray zones of waterfalls.

Satonius Endrödy-Younga 1997 was established based on a Japanese species described as Delevea kurosawai Satô 1982. Satonius is similar to Delevea Reichardt 1976 from South Africa, but can be distinguished by the sharply pointed mesocoxal margin of the metaventrite, the large discal emargination on the apical tergite of the female.

Currently, Satonius is known from Japan and China, being the only genus of Torridincolidae found in China. Recently, a large number of Satonius collected from China have been examined by researchers at Sun Yat-sen University and the Institute of Zoology, Chinese Academy of Sciences, and seven undescribed species have been identified.

S. cheni, very small, broad and convex species, body 1.2–1.4 mm in length, 0.8–0.9 mm in width. Dorsal side brown to dark brown, ventral side reddish brown in color. Side of pronotum slightly rounded, narrowly bordered. Lateral margin of elytra visible only in humeral part from above. The majority of individuals are micropterous, and only a minority of individuals are macropterous. Apical angle of metatrochanter evidently extended.

Male genitalia: Median lobe fairly broad, with apical portion bent dorsad; parameters narrow, rather long, ca. half as long as median lobe, with four long apical setae and two long subapical setae, lateral side of parameres with a wide field of pores basally.

Collected in hygropetric habitats on wet cliffs. At Xianglong Lake, it was found together with larvae of hygropetric diving beetle Hydrotrupes chinensis Nilsson, 2003. Dissection showed that some females bear two eggs within their abdomen, indicating they may lay two eggs at a time.

Only known from several close spots in type locality (Danxiashan Mt., Guangdong). This species is dedicated to Mr. Zaixiong Chen (陈再雄) (Administrative Office of Danxiashan National Natural Reserve, Shaoguan, China), for his generous help in material collecting. Chinese common name: 陈氏佐藤淘甲.

S. nigriventralis, small, fairly elongate and convex species, body 1.4–1.8 mm in length, 0.7–0.9 mm in width. Dorsal and ventral sides pitch-black with dull violet sheen. Side of pronotum rounded, broadly bordered. Lateral margin of elytra broad, widest in humeral part, narrowed posteriorly, visible throughout the elytra except for apex from above. Macropterous species. Apical angle of hind trochanter evidently extended and prolonged into a round appendix.

Male genitalia: Similar to that of Satonius schoenmanni Hájek & Fikáček, 2008. Median lobe of aedeagus with dorsal side slightly rounded in basal two thirds, straight in apical third; ventral side slightly concave in a smooth line, apically with a minute hook. Parameres rather wide, with four to five long setae apically, base with a long field of pores along ventral surface.

Collected from spray zones of a waterfall as well ashygropetric habitats on wet cliffs. Some individuals coexisted with caddisfly larvae Stactobia sp. [滴水小石蛾属] (Trichoptera: Hydroptilidae) and sometimes hide under the cases of the larvae. Dissection showed that some females bear two or three eggs within their abdomen.

Only known two spots in type locality (Qinling Mts., Shaanxi). The specific name is derived from the Latin adjectives “niger, -a, um” (= black) and “ventralis” (=ventral), referring to the pitch-black ventral color of this species. Chinese common name: 黑腹佐藤淘甲

S. panghongae, very small, fairly elongate and convex species, body 1.2–1.4 mm in length, 0.6–0.8 mm in width. Dorsal side brown, ventral side reddish brown in color. Side of pronotum slightly rounded, narrowly bordered. Lateral margin of elytra visible only in humeral part from above. Brachypterous or macropterous species. Apical angle of hind trochanter not extended, forming an obtuse angle.

Male genitalia: Median lobe narrow and slim, evenly curved towards apex; parameters strongly reduced, ca. 1/7× as long as median lobe, with only one apical seta, lateral side of parameres with a short field of pores basally.

Collected in hygropetric habitats on wet cliffs, with a thin film of flowing water covered by algal mats. Dissection showed that some females bear two eggs within their abdomen.Distribution. Know from multiple localities in Jiangxi, Hunan, Guangdong, Guangxi and Zhejiang.

This species is named after Prof. Hong Pang (庞虹) (Life Science School, Sun Yet-sen University, Guangzhou, China), a specialist on Coccinellidae. Chinese common name:庞虹佐藤淘甲

S. quzhouensis, small, fairly elongate and convex species, body 1.4–1.7 mm in length, 0.7–0.9 mm in width. Dorsal side pitch-black with obscure green sheen, ventral side largely black, with part of legs, epipleura and last abdominal segment yellowish brown. Sides of pronotum rounded, narrowly bordered. Lateral margin of elytra narrow, widest in humeral part, narrowed posteriorly but visible throughout the elytra except for apex from above. Macropterous species. Apical angle of hind trochanter strongly extended, prolonging into a short digitus.

Male genitalia: Median lobe narrow and slim, evenly curved towards apex, apex narrowly rounded, without a hook; parameres short and stout, with four long setae on apex and two short setae located subapically, lateral side of parameres with a long field of pores basally.

Known from Zhejiang (Quzhou) and Anhui (Huang Shan). This species is named after the type locality, Quzhou Prefecture, Zhejiang Province, the hometown of the second author. Chinese common name: 衢州佐藤淘甲

S. xinhuiensis, very small, fairly elongate and convex species, body 1.2–1.4 mm in length, 0.6–0.8 mm in width. Dorsal side black, ventral side black laterally, with reddish brown central part. Side of pronotum slightly rounded, narrowly bordered. Lateral margin of elytra visible only in humeral part from above. Macropterous species. Apical angle of hind trochanter not extended, forming an obtuse angle.

Male genitalia: Median lobe rather narrow and slim, evenly curved towards apex, apex slightly expanded; parameres very slender, ca. 2/7× as long as median lobe, with only one apical seta, apical seta shorter than parameres, lateral side of parameres with a short field of pores basally.

Collected in hygropetric habitats, with thin film of water flowing on rock covered by algal mat. Only know from the type locality (Xinhui, Guangdong). This species is named after the type locality, Xinhui District in Jiangmen Prefecture, Guangdong Province. Chinese common name:新会佐藤淘甲

S. zhangi, small, broad and convex species, body 1.5–1.8 mm in length, 0.9–1.3 mm in width. Dorsal side dark brown with greenish sheen, ventral side reddish brown with epipleura and legs yellow. Side of pronotum rounded, fairly broadly bordered. Lateral margin of elytra quite broad, visible throughout the elytra except for apex from above. Macropterous species. Apical angle of hind trochanter strongly extended, prolonged into short digitus.

Male genitalia: Median lobe quite broad, evenly curved towards apex; parameres short and stout, with four long apical setae and two short subapical setae, lateral side of parameres with long field of pores basally.

Known from two localities in Hunan Province. This species is dedicated to Mr. Youxiang Zhang (张佑祥) (Jishou University, Jishou, China), for his kind help in material collecting. Chinese common name:张氏佐藤淘甲

S. zhenhuai, small, broad and convex species, body 1.8–1.9 mm in length, 1.1–1.2 mm in width. Dorsal side dark brown with weak greenish sheen, ventral side reddish brown with epipleura and legs yellowish. Side of pronotum slightly rounded, fairly broadly bordered. Lateral margin of elytra narrow, visible throughout the elytra except for apex from above. Macropterous species. Apical angle of hind trochanter evidently extended, prolonged into a round appendix.

Male genitalia: Median lobe quite broad, dorsal side slightly rounded in basal two thirds, apical third slightly bent dorsad, ventral side distinctly convex in the middle; parameres short and stout, with four long apical setae and two short subapical setae, lateral side of parameres with wide field of pores basally.

Only known from the type locality (Dabieshan Mt., Hubei). This species is dedicated to the collector of the type material, Dr. Zhenhua Liu (刘振华) (Institute of Zoology, Guangdong Academy of Sciences, Guangzhou). Chinese common name:振华佐藤淘甲

Original research

Zu-Long Liang, Zhuo-Yin Jiang, Johannes Bergsten, Feng-Long Jia & Si-Qin Ge (2024). A review of the genus Satonius Endrödy-Younga from China with description of seven new species (Coleoptera: Myxophaga: Torridincolidae). Zootaxa 5528 (1): 089–105, DOI:10.11646/zootaxa.5528.1.8

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