Pterostichus (Morphohaptoderus), Tschitscherine, 1898

Subgenus Morphohaptoderus Tschitschérine, 1898 View in CoL

Morphohaptoderus Tschitschérine 1898: 190. [Type species: Haptoderus maximus Tschitschérine, 1889, by subsequent designation of Jeannel, 1937: 9]. Jeannel, 1937: 9. Jedlička, 1962: 231. Sciaky, 1994: 1. View in CoL

Diagnosis.

Species of the subgenus Morphohaptoderus can be recognized among the Chinese and Southeast Asia Pterostichus by the following combination of characters: body relatively short and wide; elytra elliptic and depressed, not parallel-sided, surface usually iridescent or shagreened (only in females); dorsum dark reddish brown to black; basal foveae of pronotum usually with distinct inner and outer sulci; metacoxae with three setae; fifth tarsomeres usually setose ventrally; metepisternum not longer than wide; right paramere very short, apex rounded (except for Pterostichus dundai Sciaky, 1994 ); apex of aedeagus often hooked or denticulate.

Subgeneric characters.

Small to medium-sized Pterostichus ( 4.6–12.6 mm); elytra elliptic, slightly arcuate laterally, not parallel-sided; dorsum dark reddish brown to black; males usually with linear microsculpture (Fig. 1 H View Figure 1 ) on elytra, often forming iridescent luster; females sometimes with matte elytra formed by granular microsculpture (Fig. 1 I View Figure 1 ). Head relatively small to slightly thickened, always narrower than pronotum; submentum with one or two setae on each side; antennae reaching or slightly exceeding elytral base, antennomere 3 with a few long primary setae forming an apical ring (Fig. 1 B View Figure 1 ), sometimes also with short accessory setae along inner margin (Fig. 1 A View Figure 1 ). Pronotum various in shape, mostly nearly circular; posterior angles often distinct but highly variable across different species; basal foveae shallow, usually forming distinct inner and outer sulci, with area between lateral margin and outer sulcus often relatively flat and not ridged. Elytra flat and oblong, striae usually relatively deep; parascutellar stria absent or present; elytral humerus usually with a tooth; interval 3 often with one to five setigerous pores but without setigerous pores in P. glabellus Fedorenko, 2023 , and some undescribed species from China. Length of metepisternum approximately equal to its basal width. Sternite VII with one seta on each side in males and two in females; male sternite VI or VII usually without secondary sexual modification, seldom with shallow depression or wrinkles (Fig. 2 View Figure 2 ). Metacoxae with three setae, the medial-posterior seta present ( Shi and Liang 2015: fig. 137); metatrochanters with a seta; fifth tarsomeres often setose ventrally (Fig. 1 F – G View Figure 1 ), asetose in some species from eastern China and Vietnam (Fig. 1 E View Figure 1 ). Apical orifice of aedeagus deviated to left; shape of apical lamella variable among different species, often hooked, denticulate, or twisted; right paramere very short, apex rounded (except for P. dundai Sciaky, 1994 ). Gonocoxite 2 of female ovipositor falciform, outer margin with two to four ensiform setae, dorsal margin with one to three ensiform setae, ridged distal to the seta.

Recognitions among Chinese subgenera of Pterostichus .

In most Chinese subgenera of Pterostichus , the metacoxa bears two lateral setae: one close to the posterior angle and the other to the anterior margin (setae 1 and 2 in Shi and Liang 2015: fig. 137). However, four Chinese subgenera possess an additional seta near the medial angle (seta 3 in Shi and Liang 2015: fig. 137): Tschitscherinea Berg, 1898 , Morphohaptoderus Tschitschérine, 1898 , Cryobius Chaudoir, 1838 , and Huaius Tian & Huang, 2019 . Based on this synapomorphy and phenetic similarities, these four subgenera are hypothesized to be more closely related to each other than to other subgenera in the Chinese fauna. Among them, members of Morphohaptoderus can generally be recognized by their relatively stout body form and the very short right paramere of the male genitalia. Nevertheless, these diagnostic characters are not universally applicable to all species of the subgenus, suggesting that the group may not be monophyletic. Detailed comparisons among Morphohaptoderus , Tschitscherinea , and their relatives were provided in our previous study ( Yin et al. 2024).

After examining the type specimens of two species, P. megaloderus Sciaky, 1994 , and P. yulongshanensis Sciaky, 1997 (Fig. 30 A, B View Figure 30 ), which were previously assigned to the subgenus Morphohaptoderus , it was found that they do not conform to this subgenus in terms of two key characteristics: the metacoxae with only two setae, with the medial seta absent (Fig. 30 F View Figure 30 ); and the apex of the right paramere slightly pointed (Fig. 30 E View Figure 30 ). These characteristics, together with the general features of their habitus and male genitalia, indicate that these two species are closely related to some members of the subgenus Neohaptoderus , such as P. berezowskii Tschitschérine, 1898 . Therefore, the following new subgeneric assignments are proposed herein: P. ( Neohaptoderus) megaloderus and P. ( Neohaptoderus) yulongshanensis . Thus, prior to the present study, the subgenus Morphohaptoderus comprised 34 species.

Distribution and diversity.

Including the ten new species described in this study, the subgenus Morphohaptoderus now comprises a total of 44 species. Most of them (40 species) are endemic to China, distributed across Yunnan, Sichuan, Shaanxi, Gansu, Guizhou, Hubei, and Chongqing provinces, with an exceptionally high species richness in Sichuan, Shaanxi, and Hubei. Additionally, three species are distributed in northern Vietnam ( Fedorenko 2023), and one species occurs in northern Myanmar ( Wrase and Schmidt 2006).

In Sichuan and Yunnan, species of Morphohaptoderus generally inhabit cloud forests at relatively high altitudes, ranging from approximately 3000 to 4000 m. In eastern provinces such as Hubei and Chongqing, some species occur at lower altitudes, even below 1000 m. Based on our examined specimens, numerous new species await description.

Taxonomical notes.

Prior to the present research, we had studied all described species of Morphohaptoderus from China. The following characters are considered important both for species determination and for inferring phylogenetic relationships: setae on the submentum, number of setigerous pores on elytral interval 3, and the median lobe of the aedeagus, particularly the modification of the apical lamella and the presence of ventral ridges.

In most members of Pterostichus , the submentum has two setae on each side: a longer medial seta and a shorter lateral seta. In some cases, the lateral seta may be absent, resulting in only one seta on each side of the submentum. Based primarily on this character, the Chinese species of Morphohaptoderus can be classified into two major groups. Division I: The submentum has two setae on each side. Species in this group tend to have smaller body sizes; if the apical lamella of the aedeagus is modified, it is hooked on the right margin; elytral interval 3 has two or more (usually three or four) setigerous pores, with the basal pore always adjacent to stria 3. Fifteen described species belong to this group, primarily distributed in the high-altitude Hengduan Mountain System in Sichuan and Yunnan provinces, with a few also occurring in Shaanxi and Gansu. Division II: The submentum has only one seta on each side. Species in this group exhibit a body size range from very small to large; the apical lamella of the aedeagus is often modified, with a denticle on the left margin; the median lobe of the aedeagus often has ventral ridge; and elytral interval 3 normally has three or fewer (usually two) setigerous pores, all of which are often adjacent to stria 2 (except for three species in Hubei). Twenty-five described species belong to this group, including all 14 species distributed in Hubei, seven additional species of the maximus group (defined below), and four remaining species: P. schuelkei Sciaky & Wrase, 1997 , P. wenxianensis Allegro & Sciaky, 2010 , P. janatai Sciaky & Wrase, 1997 , and P. parvicollis Sciaky & Wrase, 1997 . These species are primarily distributed in the relatively low-altitude Qinling Mountain System in Hubei and Shaanxi, with a few also occurring in mountainous regions of southern China.

In Division II, 13 species share a similar aedeagus type, characterized by a large denticle on the left margin of the median lobe and a strongly downward-bent apex of the apical lamella (Figs 1 C View Figure 1 , 12 View Figure 12 , 13 View Figure 13 ). A species group named the maximus group is proposed for these species, as this group is clearly monophyletic based not only on the above specific characters of the male genitalia but also on the following: the ventral margin of the aedeagus is more or less ridged; females often exhibit granular microsculpture on the elytra, giving them a shagreen appearance; and elytral interval 3 usually has two setigerous pores, with the first pore always adjacent to stria 2. Compared with other species in Division II, P. hubeicus Facchini & Sciaky and P. yaotiao sp. nov. are most closely related to the maximus group, as they also possess a denticle (although very small and indistinct) on the left margin of the apical lamella of the aedeagus.

Except for the six species from Hubei (the first six species in the present paper), the following seven species also belong to the maximus group: P. maximus Tschitschérine, 1889 ; P. dundai Sciaky, 1994 ; P. huashanus Sciaky, 1994 ; P. lingshanus Sciaky & Wrase, 1997 ; P. chungkingi Jedlička, 1932 ; P. irideus Sciaky, 1994 ; and P. guizhouensis Sciaky, 1997 . The first four species listed are distributed in the Qinling Mountains, with one species ( P. maximus ) from Gansu and the remaining species from Shaanxi. The last three species are distributed in three isolated mountain ranges: Jinfo Mountain ( Chongqing), Emei Mountain ( Sichuan), and Fanjing Mountain ( Guizhou).

To facilitate descriptions of male genitalia in the maximus group, it is necessary to introduce three morphological terms: lamellar denticle is used to describe the tooth-like structure formed by the upward bending of left margin of apical lamella; lamellar apex refers to the portion of apical lamella located distally from the base of lamellar denticle; and lamellar base refers to the portion of apical lamella located proximally to the lamellar denticle (Fig. 1 C View Figure 1 ). When describing species in the maximus group, the lengths of these three parts were measured to characterize variations in the apical lamella. Measurements were taken from the intersection points of their axes in the left lateral view, extending to the apical margin of the apical orifice and to the apical tips of the lamellar apex and lamellar denticle (Fig. 1 C View Figure 1 ).

In the maximus group, the ventral surface of the median lobe of the aedeagus typically bears three ridges. The right ridge is located on the right-ventral margin of the median lobe (the right-ventral margin corresponds to the left side of the median lobe in ventral view). When entire, it extends from the aedeagal base to the extreme apex, forming a continuous margin on the right-ventral side of the basal portion and apical lamella; however, it is partially absent in many species. The median ridge is positioned along the midline of the ventral surface. When entire, its base does not reach the aedeagal base, and its apex extends at most to the midlevel of the apical orifice. The left ridge is situated on the left-ventral margin of the median lobe. Its base nearly reaches the aedeagal base, with a straight or sinuate structure near the base, and the apex terminates at the left-basal corner of the apical orifice. Among the six Hubei species of the maximus group, all three ridges described above are fully developed only in P. lisao sp. nov. (Fig. 14 B, C View Figure 14 ). In the other species, some ridges are absent or poorly defined.

Key to species of subgenus Morphohaptoderus Tschitschérine, 1898 from Hubei