Eobroscus bhutanensis Morvan, 1982

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 : 161-175

15. Eobroscus bhutanensis Morvan, 1982

Figures 5a , 38 , 39 , 43 , 47-50

Eobroscus bhutanensis Morvan, 1982:77. Holotype, a male, deposited in NHMB. Type locality: Bhutan, near Thimphu.

Eobroscus uenoi Morita, 1995:8. Holotype, a male, deposited in NSMT. Type locality: Vietnam, Lào Cai, Hoang Lien Son Moutains, N of Mt. Fan Si Pan, 1840 m (synonymized by Schmidt et al. 2013:15).

Diagnosis. Fig. 38a . Because E. bhutanensis is the only species of the genus in the region, the generic diagnosis serves also to distinguish members of this species.

Habitat distribution. Within the study area, members of this species were collected mainly under large stones at the edges small streams ( Fig. 43 ), however one specimen was found under a stone along a roadcut though mixed broadleaf evergreen and conifer forest.

Within the Gaoligong Shan region, this species occurs at moderate elevations, with our records documenting its occurrence in the 2527 to 3100 m range ( Fig. 49 ).

Geographical distribution within the Gaoligong Shan. Fig. 38b . We examined a total of nine specimens (seven males and two females) from the following localities: Fugong County: Lishadi Township (2.0 to 4. 3 km above Shibali on Shibali Road, 27.17262°/98.76943° to 27.17772°/98.75485°, 2700-2826 m, 3 May 2004, D.H. Kavanaugh, H.B. Liang & C.E. Griswold collectors [one male; CAS]) . Gongshan County: Cikai Township ( Danzhu (27.63056°/98.62056°, 2600 m, 14 April 2002, H.B. Liang & W.D. Ba collectors [ one male; IOZ]), (Danzhu He (13.5-13.8 airkm SSW of Cikai, 27.63267°/98.60861° to 27.63331°/98.60356°, 2720-2840 m, 30 June – 5 July 2000, D.H. Kavanaugh, C.E. Griswold, H.B. Liang, D. Ubick & D.Z. Dong collectors [ five males; CAS, IOZ]), (No. 12 Bridge Camp area (16.3 airkm W of Cikai, 27.71503°/98.50244°, 2775 m, 15-19 July 2000, D.H. Kavanaugh, C.E. Griswold, H.B. Liang, D. Ubick & D.Z. Dong collectors [ one male; CAS]). Lushui County : Luzhang Township (Yaojiaping He at Pianma Road, 25.97722°/98.71091°, 2527 m, 19 May 2005, D.H. Kavanaugh, H.B. Liang & D.Z. Dong collectors [ one female; IOZ]).

Members of this species were collected only in the northern two-thirds of the study area, in Core Areas 2, 3 and 5 ( Fig. 48 ), and only on the eastern side of the mountain range. However, the relatively broad geographical range of this species overall (see below) suggests that it probably occurs in the other cores areas as well but has not yet been recorded from them.

Overall geographical distribution. Fig. 47 . This species has been recorded from Bhutan, China (Gansu, Shaanxi, Sichuan, Xizang (Tibet), Yunnan), India (Arunachal Pradesh), Myanmar, Nepal, and northern Vietnam. Its occurrence in the study area is near the midpoint of both its known east/west and north/south geographical ranges.

Geographical relationships with other Eobroscus species. Representatives of neither of the other Eobroscus species have been recorded from within the study area or from any other area where E. bhutanensis has been found with one exception. A single specimen of E. lutshniki (in IOZ) that we examined is labeled [in Chinese characters] as from Lazikou, Gansu Province, China, an area about 2500 km SW of the nearest verified localities for that species. A specimen of E. bhutanensi s (also in IOZ) bears the same locality label. It is most likely that the specimen of E. lutshniki was mislabeled; but if not, then this would represent the only known instance of sympatry of species in the genus.

Within the study area, E. bhutanensis has been found in the same area and habitat as two other broscine species, Broscosoma danzhuense and B. ribbei ( Fig. 50 ).

Discussion

The Gaoligong Shan region is a key component of one of the world’s biodiversity hotspots ( Myers et al. 2000), where faunal elements from the Palearctic and Oriental Regions meet. These elements augment a distinct regional, largely precinctive element, probably of mixed Palearctic/ Oriental origin ( Deuve 2013), which either became isolated and evolved independently within the region or has been replaced elsewhere by present-day Palearctic and/or Oriental elements. Among the four groups studied in detail to date, the trechines and broscines are the most diverse precinctive elements in the fauna, with 25 of 29 trechine species (86%) and 11 of 15 broscine species (73%) known from nowhere else. We have found no precinctive species among either the omophronines (three species) or the zabrines (13 species).

Relative to the diversity of faunas in other areas of comparable size, the broscine fauna of the Gaoligong Shan region is exceptionally diverse and previously poorly known. Of the 15 species from the area recorded here, 11 are described as new and one additional species, Broscosoma gaoligongense , which we also had represented in our samples as new, was only recently described by Deuve and Wrase (2015). This diversity includes not only taxonomic diversity, but also exceptional diversity in morphological features, particularly within the genus Broscosoma , but also in Broscodera to a lesser degree.

No other comparable region is known to harbor two species of Broscodera . Their geographical ranges overlap in part but they appear to occupy different elevational ranges and are also non-overlapping in their respective body size ranges. Members of Broscodera chukuai are the smallest members of the genus known to date, with their size range outside the ranges of any of the other congeneric species and subspecies. Whether the differences in body size and elevational range between B. chukuai and B. gaoligongensis represent character displacement in these morphological and ecological features or have instead resulted from some other historical cause or causes will remain unclear until phylogenetic relationships among Broscodera species are better understood.

There appears to us to be at least as much morphological diversity within the Broscosoma fauna of the Gaoligong Shan region as is found within the genus throughout the remainder of its entire range. All species with members having lateral margination of the pronotum present, whether distinct on at least part of the pronotal margin, as in B. resbecqi and B. ribbei , or complete, as in B. holomarginatum , are found in this region. Broscosoma rebecqi is known only from this region, B. holomarginatum also occurs in the adjacent southeastern part of Xizhang (Tibet), and only B. ribbei is more widely distributed. No other area has as many species with the elytra humeri more or less distinct. In fact, the number of species with distinct humeri in the Gaoligong Shan region (six) is double the number (three) within the remainder of the genus. Diversity in the presence and distribution of metallic reflection on the dorsum of the body is also exceptional. For example, no described species from any another area has members which have the pronotum without metallic reflection except for the area anterior to the anterior transverse impression, where it is distinctly present in B. viridicollare members and faintly present in some members of B. bicoloratum as well. Finally, there is exceptional diversity in the genitalic structures of males in the region, particularly in the shape of the median lobe and the sclerites of its internal sac and in the shape of the left paramere. Clearly, the Gaoligong Shan region is and has been a very important area in the evolutionary history of this genus. Better understanding of that history will require phylogenetic analyses of both morphological and DNA data for the genus as a whole.

Figures

FIGURE 5. Forebody of broscine carabids, dorsal aspect. a. Eoboscus bhutanensis Morvan (CASENT1019340; Lishadi Township, Fugong County, Yunnan, China); b. Broscus punctatus (Dejean) (CASENT1011066; Heiwadi, Cikai Township, Gongshan County, Yunnan, China); c. Broscodera chukuai sp. nov. (CASENT1026168; NNE of Chukuai Lake, Bingzhongluo Township, Gongshan County, Yunnan, China); d. Broscodera gaoligongensis sp. nov. (CASENT1020104; South Fork of Yamu He, Lumadeng Township, Fugong County, Yunnan, China).

FIGURE 38. Eobroscus bhutanensis Morvan. a. Habitus (CASENT1019340; Lishadi Township, Fugong County, Yunnan, China), dorsal aspect, scale line = 1.0 mm; b. Map showing locality records (blue circles) for this species in the Gaoligong Shan region, scale line = 100 km.

FIGURE 39. Male genitalia, Eobroscus bhutanensis Morvan (CASENT1001452; Danzhu He drainage, Gongshan County, Yunnan, China). a. Right paramere, lateral aspect; b. Left paramere, lateral aspect; c. Median lobe, left lateral aspect; d. median lobe, ventral aspect; scale line = 1.0 mm.

FIGURE 43. Photographs of habitat for broscine species in the Gaoligong Shan region; a. Danzhu He drainage, 2840 m, 27.633°/98.604°, Cikai Township, Gongshan County, Yunnan (habitat for Broscosoma danzhuense sp. nov. and Eobroscus bhtanensis Morvan). Photo by David H. Kavanaugh.

FIGURE 47. Map showing approximate known overall geographical distributions of broscine species occurring in the Gaoligong Shan region as well as outside the study area. a. Broscus punctatus (Dejean); b. Eobroscus bhutanensis Morvan; c. Broscosoma ribbei Putzeys; d. Broscosoma holomarginatum sp. nov. Modified from Wikimedia Commons, World Atlas of the World, at URL: http://upload.wikimedia.org/wikipedia/commons/8/8f/Whole_world_-_land_and_oceans_12000.jpg. Scale line = 500 k

FIGURE 48. Chart showing the representation of broscine species in project-designated Core Areas (see Fig. 3) in the Gaoligong Shan region.

FIGURE 49. Chart illustrating the altitudinal ranges of broscine species represented in the Gaoligong Shan region. Green bars mark the elevational range recorded for each species.

FIGURE 50. Chart illustrating the co-occurence (syntopy) of broscine species in samples from the same habitats and at the same sites in the Gaoligong Shan region. Incidents of syntopy marked in black represent confirmed co-occurrence, those marked in grey not confirmed by records but likely.