Pterostichus (Chinapterus), Berlov, 1998

Dorjderem, Sodnomtsog, Shi, Hongliang & Liang, Hongbin, 2020, The genus Pterostichus in China III: a brief review of subgenus Chinapterus Berlov (Coleoptera, Carabidae) with descriptions of two new species, ZooKeys 953, pp. 61-83 : 61

Subgenus Chinapterus Berlov, 1998

Chinapterus Berlov, 1998: 14. Type species: Pterostichus balthasari Jedlička, 1937 [= Pterostichus singularis Tschitschérine, 1889], by original designation.

Diagnosis.

Body slightly convex. Elytral striae regular, third interval with two or three setigerous pores. Metepisternum slightly wider than length. Mesofemur with four or more setae on ventral surface. Elytral plica absent or indistinct. Right paramere of male genitalia falciform, with somewhat elongated apex. Spermatheca with seminal canal and receptaculum not differentiated.

Subgeneric characters.

Medium size, body length 9.0-15.0 mm. Black, elytra slightly shiny, without metallic luster. Submentum with two long setae on each side. Pronotum cordate or quadrate; basal foveae deep, inner and outer grooves indistinctly separated or outer groove absent; one baso-lateral seta inserted on basal angle. Elytra striae straight and continuous, neither interrupted nor sinuate; interval microsculpture isodiametric, similar in male and female, third interval usually with two or three setigerous pores, fifth interval without pore; ninth interval with umbilical series slightly sparser in the middle than basal and apical areas; elytral plica indistinct; scutellar stria present; basal pore present or not. Metepisternum slightly wider than length. Terminal ventrite of males slightly depressed or without modification. Mesofemur with four or more setae on ventral surface, with a spine near apex; metacoxae with two setae; metatrochanters without seta. Fifth tarsomere with or without setae on ventral side. Apical orifice of aedeagus obviously twisted to left side; apical lamella narrow, short; right paramere falciform, apex more or less elongate and bent; endophallus bent to ventral-left or venter, gonopore opened to the base, with a large cap-like sclerotized gonopore piece (Figs 7-9 ). Gonocoxite II of ovipositor stout or slightly slender and bent, apex rounded, inner and outer margin each with one ensiform spine, apex with two very short nematiform setae in groove (Figs 60-65 ). Spermatheca tube-like, surface glabrous, receptaculum not differentiated from seminal canal, base of seminal canal sclerotized; spermathecal gland very fine, atrium and gland duct not differentiated, connected to the middle of spermatheca (Figs 58 , 59 ).

Distribution.

This subgenus is endemic to China. A total of four species are distributed in Qinghai, Sichuan, Gansu, and Ningxia.

Comparison.

In its original description (Berlov, 1998), the subgenus Chinapterus was erected based on type species Pterostichus balthasari Jedlička, which was formerly a member of the subgenus Euryperis Motschulsky ( Jedlička, 1962) and was subsequently synonymized with Petrophilus Chaudoir ( Kryzhanovskij et al., 1995). Chinapterus is similar to Euryperis in having metepisternum slightly wider than length, metatrochanters without seta, and pronotum posterior angles widely rounded (only for P. singularis ). But, Chinapterus is quite different from Euryperis in the following aspects: (1) mesofemur with four or more setae on the ventral side (with two setae in Euryperis ); (2) elytral plica absent or indistinct (distinct in Euryperis ); (3) spermatheca with seminal canal and receptaculum not differentiated (well differentiated in Euryperis ).

Among the Chinese subgenera of Pterostichus , Chinapterus is most similar to the subgenera Sinoreophilus and Metallophilus in external appearance, and having the mesofemur with four or more setae near the hind margin, the metepisternum width subequal to its length, but differs in: (1) right paramere falciform, with the apex more or less elongate and bent; (2) elytral microsculpture isodiametric, similar in both sexes (in the other two subgenera, right paramere rounded triangular, apex not elongate, nor slightly bent; elytral microsculpture granular in females, isodiametric in males). Comparisons with other similar subgenera present in the key to subgenera.

Notes on systematics.

Among all subgenera of Pterostichus from China, Chinapterus is doubtless closely related to other five subgenera ( Platysma , Adelosia , Metallophilus , Sinoreophilus , Plectes ) and shares the following important characters: (1) mesofemur with four or more setae along posterior margin; (2) elytral plica absent or indistinct; (3) metatrochanters without seta; (4) spermatheca tube-like, seminal canal and receptaculum not differentiated. These six subgenera form a monophyletic group (the Platysma group as defined here) supported by synapomorphic characters 1, 2, and 3 (character polarities discussed in this section follow Bousquet, 1999: 32-36). Except for the Chinese fauna, Myosodus , a subgenus centered in the Caucasus, also belongs to this group.

Among the above four characters, characters 1 is exclusive for the Platysma group in Pterostichus and character 4 is plesiomorphic. The undifferentiated spermatheca is unusual in Pterostichus and may suggest a relatively basal position of the Platysma group in the genus. So far as we know, all species of the Platysma group have a distinctive form of the female reproductive tract: spermatheca tube-like, seminal canal and receptaculum not differentiated, spermathecal canal inserted between the midpoint to the apical third of the spermatheca. In contrast, for most subgenera of Pterostichus , the spermatheca is usually very long with the seminal canal and receptaculum differentiated. If not so distinctly differentiated, the seminal canal is at least a little slenderer than the receptaculum, as in the subgenus Orientostichus . Except the Platysma group, only the subgenus Argutor and its relatives (five subgenera from China) have the undifferentiated spermatheca, but their spermathecae are always very short with the spermathecal canal inserted near the basal fourth of spermatheca.

The relationships among subgenera of the Platysma group are quite unclear, and even the monophyly of several subgenera is questioned. The subgenera Platysma and Sinoreophilus can be differentiated by plesiomorphic characters only, while other subgenera are merely defined by one or two apomorphic characters. Except for Adelosia (monotypic) and Plectes (includes two very closely related species), the monophyly of the other four subgenera are difficult to demonstrate.

We here redefine the subgenus Chinapterus and assign P. przewalskyi together with two new species very closely related to it into the subgenus for the following similarities: metepisternum length subequal to its basal width and right paramere falciform, apex rather elongated and bent. These two apomorphic characters may support the subgenus Chinapterus and can clearly differentiate it from all other related Chinese subgenera. However, the monophyly of Chinapterus is still questioned, because the elongate right paramere is also present in other subgenera of the Platysma group, including part of Platysma and all members of Myosodus . Moreover, P. singularis and P. przewalskyi do not look similar in their general appearances, and simply from the shape of right paramere, the former species is more similar to some species of Platysma while the latter is more like Myosodus . Nevertheless, the present definition of the subgenus Chinapterus is good for convenient taxa recognition at present. Under this, all Chinese Pterostichus species with multisetose mesofemora can be assigned to each subgenus. We expected an in-depth phylogenetic study will propose a better and more objective assignment of subgenera in the future.

When the present study on Chinapterus was conducted, we examined all Pterostichus species belonging to the Platysma group from China. We found that, P. lanista ( Tschitschérine), P. militaris ( Tschitschérine), and P. peilingi Jedlička should be moved into the subgenus Sinoreophilus for the following characters: mesofemur with four or more setae along posterior margin; elytra striae regular; metepisternum short, length subequal to the width of anterior margin; right paramere short and straight.

Figures

Figures 7 - 23. male genitalia of Pterostichus (Chinapterus) singularis Tschitscherine. 7 - 9 Endophallus, LT: Pass Xining-Guide (IZAS) 7 right lateral view 8 left lateral view 9 ventral view, abbreviations as stated in text 10 - 11 median lobe of aedeagus, LT: Wushaoling (IZAS) 10 dorsal view 11 left lateral view 12 - 23 right paramere, inner face 12 LT: Lajishan (IZAS) 13 LT: Lajishan (IZAS) 14 LT: Pass Xining-Guide (IZAS) 15 LT: Guoshizeshan (IZAS) 16 LT: Lajishan (IZAS) 17 LT: E Qilianshan (IZAS) 18 LT: Dadongshu pass (IZAS) 19 LT: Dadongshu pass (IZAS) 20 LT: Lenglongling (IZAS) 21 LT: Wushaoling (IZAS) 22 Holotype of P. singularis (ZIN) 23 Lectotype of P. balthasari (NMPC). Scale bars: 0.5 mm.

Figures 58 - 65. female genitalia of Pterostichus (Chinapterus) spp. 58, 59 Female reproductive system 58 P. singularis, LT: Pass Xining-Guide (IZAS) 59 P. przewalskyi, LT: Zhenqin (IZAS). Scale bar: 0.5 mm. 60 - 65 Female ovipositor 60, 61 P. przewalskyi, LT: Zhenqin (IZAS) 62, 63 P. lianhuaensis sp. nov., Paratype LT: Lianhuashan (IZAS) 64 - 65 P. singularis, LT: Pass Xining-Guide (IZAS) 60, 62, 64 Gonocoxite II, inner view, 61, 63, 65 Gonocoxite I, II, ventral view. Scale basr: 0.2 mm.