Broscosoma Rosenhauer, 1846

Kavanaugh, David H. & Liang, Hongbin, 2021, Inventory of the Carabid Beetle Fauna of the Gaoligong Mountains, Western Yunnan Province, China: Species of the Tribe Broscini (Coleoptera: Carabidae)., Proceedings of the California Academy of Sciences 67 (4), pp. 85-182 : 108

Genus Broscosoma Rosenhauer, 1846

Broscosoma Rosenhauer, 1846:1 . Type species: Broscosoma baldense Rosenhauer, 1846:4 .

Diagnosis. Members of this genus can be distinguished from those of other broscine genera in the region by the following combination of character states: body small to moderate in size (BL>13.0 mm); body surface with or without metallic reflection; head with post-temporal transverse sulcus moderately deep and broadly or narrowly punctate; genal ridge present, but varied in extent; maxillae with two setae on eustipes, stipes with dorsobasal setae at least half as long as ventrobasal setae; mentum with one pair of setae present, paramedial region moderately to deeply foveate; submentum with one to three pairs of setae; antennae with antennomeres 3 and 4 glabrous except for apical whorl of fixed setae; pronotum with basolateral setae absent; elytra with parascutellar seta present, umbilicate setal series comprised of one post-humeral and two preapical setae; male protarsi with pads on adhesive setae ventrally on tarsomeres 1 to 3, and mesotarsi with pads of adhesive setae on tarsomeres 1 and 2.

Taxonomic notes. The generic diagnosis presented above properly applies only among those species occurring in the study area. Members of some species of the genus occurring elsewhere present exceptions to several of the character states listed. Even the features most widely applied as characteristic of the genus are subject to exceptions, including among species of the study area. Roig-Juñent (2000) distinguished Broscosoma species from Miscodera arctica (Paykull), 1798 principally on differences in the lateral margination of the pronotum (present in Miscodera and absent from Broscosoma ) and paramedial foveae on the mentum (present in Miscodera and absent from Broscosoma ). However, we have found lateral margination of the pronotum present in at least some form ( Figs. 9 a-d) in several of the species occurring in the study area and fully present in members of one species. Similarly, we have found that members of most Broscodera species in the study area have at least shallow paramedial foveae on the mentum, and one species has foveae comparably deep to those of M. arctica members. Other features listed by Roig-Juñent in his description of the genus are also subject to greater variation among Broscosoma species in the study area than was represented in his sample of only three species. Among these are development of the genal (or “temporal”) ridge ( Figs. 10 a-d), number of pairs of setae on the submentum, and pubescence on antennomere 4.

Since Sciaky and Facchini (2005) presented their excellent key to the Broscosoma species of China, the number of species known from that country has more than tripled, from eight to 26, not including any of the species newly described herein. Clearly, a new key to Chinese species is needed; but new species continue to be discovered (see Jiang et al. 2020 and Jiang et al. 2021 for the most recent additions) at such a rate as to make creating such a key a rapidly ‘moving target’, which we plan to attempt, nonetheless, in the near future.

Diversity and geographical distribution. To date, 43 species and an additional five subspecies of Broscosoma have been described. The genus is strictly Palearctic in distribution, with a range extended from the Alps of northern Italy eastward to Japan and Taiwan, but with wide disjunctions apparent. The main distributional gaps occur between (1) northern Italy and the Caucasus Mountains, (2) the Caucasus and the Himalaya in central Nepal, and (3) Chongqing and Shaanxi Provinces and Fujian Province, Taiwan, and Japan.

Figures

FIGURE 9. Prothorax, Broscosoma species, oblique left lateral aspect. a. a. B. holomarginatum sp. nov. (CASENT1016746; 0.5 km N of Kongdang, Dulongjiang Township, Gongshan County, Yunnan, China); b. B. resbecqi sp. nov. (Holotype; Siran Wang, Dulongjiang Township, Gongshan County, Yunnan, China); c. B. ribbei Putzeys (CASENT1025337; 0.5 km WSW of Maku village, Dulongjiang Township, Gongshan County, Yunnan, China); d. B. purpureum sp. nov. (CASENT1015871; Moqie Wang, Dulongjiang Township, Gongshan Yunnan, China). White arrows denote end points of lateral margination.

FIGURE 10. Head, Broscosoma species, lateral aspect. a. B. furvum sp. nov. (CASENT1020001; first cirque S of Shibali Yakou, Fugong County, Yunnan, China); b. B. gaoligongense Deuve and Wrase (CASENT1027285; just W of Fenxue Yakou, Pianma Township, County, Yunnan, China); c. B. purpureum sp. nov. (CASENT1015871; Moqie Wang, Dulongjiang Township, Gongshan Yunnan, China). White arrows denote endpoints of genal ridge.