Seven new species of blackclock beetle (Pterostichus Bonelli 1810) in subgenus Orientostichus Sciaky & Allegro 2013

NEWS - Researchers report 7 new species in the subgenus Orientostichus Sciaky & Allegro 2013 from Southeast China, all of which belong to the Pterostichus prattii species group Bates 1890: Pterostichus (Orientostichus) sinuosus, P. (O.) shan, P. (O.) luoxiaoensis, P. (O.) separatus, P. (O.) skanda, P. (O.) fujianensis, P. (O.) deliquus and P. (O.) matalini Fedorenko 2023 were first recorded in China.

Orientostichus contains a number of large Pterostichus species Bonelli 1810 that are common not only in evergreen broadleaf forests and high mountain cloud forests. A total of 25 species have been described in this subgenus, which are distributed throughout southern China and Southeast Asia.

These species are classified into 4 species groups: P. pulcher Sciaky & Allegro 2013, P. curtatus Fairmaire 1886, P. lesticoides (Straneo, 1939) and P. prattii Bates 1890. The first two groups are known only from the high mountains of southwestern China, while the other two are distributed in temperate, subtropical and warm-climate areas of Southeast Asia.

Now researchers find that specimens previously assigned to P. prattii actually belong to several different and more new species with a special focus on the male sexual modification characters on sternite VII and the male genitalia endophalus.

Sinuate blackclock (Pterostichus sinuosus), Chinese common name: 曲缘通缘步甲. A3 without or with very few accessory setae; elytra with isodiametric microsculpture in males, with granular microsculpture in females; pronotum lateral margin distinctly sinuate before posterior angles; msctuberculate.

This species can be distinguished from all other species of the subgenus from southeastern China by the distinctly sinuous lateral margin of the pronotum before the posterior angle, whereas in all other known species the pronotal lateral margin is straight, barely sinuous or slightly curved before the posterior angle.

Three parallel carinas blackclock (Pterostichus shan), Chinese common name: 彡通缘步甲. A3 without accessory setae; pronotum nearly circular; elytra with isodiametric or very weakly transversal microsculpture in males, granular in females; msc tuberculate, with three parallel transversal carinas.

This species can be distinguished from all other species of the subgenus from southeastern China by the distinctive sternite VII of the males. For dorsal view, it can be recognized by the circular pronotum, A3 without accessory setae, and females with granular microscapulae on the elytra.

Luoxiao Mountains blackclock (Pterostichus luoxiaoensis), Chinese common name: 罗霄通缘步甲. A3 without accessory setae; pronotum subcordate, anterior margin wider than posterior margin; elytra with isodiametric microsculpture similar in both sexes; msc ridged, apical carina extended into median table.

This new species can be distinguished from most other species of the subgenus from Southeast China by its pronotum strongly tapering towards the base, so that PAW/PBW is more than 1.0.

Separated blackclock (Pterostichus separatus), Chinese common name: 离沟通缘步甲. A3 with accessory setae; pronotal basal foveae with the basal sulcus apex more or less exceeding the base of the inner sulcus, the inner sulcus not connected with the basal sulcus; elytra with isodiametric microsculpture in both sexes, sometimes slightly transversal in males; msc with short paramedian projections, without paramedian carina.

The new species can be distinguished from most similar species of the subgenus by A3 having numerous accessory setae.

Skanda Bodhisattva blackclock (Pterostichus skanda), Chinese common name: 韦陀通缘步甲. A3 with accessory setae; basal foveae distinctly punctate, inner sulcus connected to basal sulcus; elytra with isodiametric microsculpture in males, with granular microsculpture in females; msc trident, with very long paramedian projections.

The new species can be distinguished from most similar species of the subgenus by A3 having numerous accessory setae.

Fujian blackclock (Pterostichus fujianensis), Chinese common name: 福建通缘步甲. A3 without accessory setae; elytra with transversal microsculpture in males, with granular microsculpture in females; elytra reflexed lateral margin with a flattened smooth carina in apical third; mscridged, with median fovea at center of median table.

This species can be distinguished from all other similar species by the elytra with transverse microsculpture (each web length about 2.0 times its width, in males), and the lateral margins of the elytra reflected with a smooth, flattened carina in the apical third.

Lacking sternite (Pterostichus deliquus), Chinese common name: 乌有通缘步甲. A3 without accessory setae; pronotum very large in comparison to elytra, posterior angles sharply obtuse-angled, posterior margin declined near posterior angles; elytra with slightly transversal microsculpture (mesh length/width about 1.5) on elytra; male sternite VII without distinct sexual character.

The new species is unique among all species of the subgenus from southeastern China because of the special shape of the pronotum and sternite VII of males.

Original research

Wen-Qi Yin, Jia-Heng Chen & Hong-Liang Shi (2024). Revision of the subgenus Orientostichus Sciaky & Allegro in Southeast China, with descriptions of seven new species of the Pterostichus prattii Bates species group (Coleoptera: Carabidae: Pterostichini). Zootaxa 5528 (1): 038–076, DOI:10.11646/zootaxa.5528.1.6

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