Chelonus (Carinichelonus) tabonus Sonan, 1932 comb. nov.

Figs 1–4

Chelonus tabonus Sonan, 1932: 71; Watanabe, 1934: 196; 1940: 87; He, 2004: 636.

Microchelonus tabonus: Chen & Ji, 2003: 163.

Chelonus (Carinichelonus) tabonus: Ranjith & Priyadarsanan, 2023: 470.

Chelonella yami Sonan, 1932: 74, synonymized with C. tabonus by Watanabe (1934).

Chelonella carinata Shestakov, 1940: 11; Tobias, 2010: 261 (homonym of C. carinatus Provancher, 1881).

Chelonus carinatikovi Shenefelt, 1973: 878 (nom. nov. for C. carinatus Shestakov, 1940).

Microchelonus (Carinichelonus) carinatikovi: Tobias, 2010: 261.

Microchelonus (Carinichelonus) cavifrons Tobias, 2000: 461 . Syn. nov.

Material examined. 1 female, Rugao, Jiangsu Prov., China, 1980, Min Huang, No. 804095; 16 females and 9 males, Shangyu, Zhejiang Prov., China, 27. V.1973 , Tiansen Xu, No. 740307 (25); 1 female and 2 males, Leigong Mt., Guizhou Prov., China, 31. V.2005 , Hongying Zhang, Nos. 20059226, 20059232, 20059234; 1 female Xiamen, Fujian Prov., China, 28.VII.1988 , Junhua He, No. 887960; 1 female, Nanling, Guangdong Prov., China, 9–18.VII.2005 , Yali Cai, No. 200609672; 6 males, Guilin, Guangxi Prov., China, 22.IV.1987, Junhua He, Nos. 878630, 878631, 878632, 878633, 878634, 878635 .

Biology. Unknown.

Distribution. China (Fujian, Guizhou, Jiangsu, Shandong, Taiwan, Yunnan, Zhejiang); Indonesia; Japan; Korea.

Note. Tobias (2000) used Microchelonus (Carinichelonus) cavifrons Tobias, 2000 as type species to establish the new subgenus Carinichelonus . The following characteristics were used: frons deeply excavated posteriorly and smooth; carapace very broadly truncate apically and ventral opening slightly longer than half length of carapace and opening surrounded by a lamelliform carina. We could not find any clear differences between C. cavifrons and C. tabonus Sonan, 1932 and, therefore, we consider the first a junior synonym of the second. Chen & Ji (2003) transferred Chelonus tabonus Sonan, 1932 from the genus Chelonus to Microchelonus, but there is no apical aperture at the end of the male carapace in posterior view, therefore, we agree with the inclusion in the subgenus Carinichelonus .

Two species included in Chelonus s.str. viz., C. (C.) glomerosus sp. nov. and C. (C.) akinakes sp. nov., are similar to C. tabonus, considering all have their carapace opening surrounded by a wide lamelliform carina. However, C. (Carinichelonus) tabonus differs by having the frons with two distinct lateral carinae and a deep smooth depression posteriorly.