Pterostichus ( Morphohaptoderus ) chachi, Wu & Chen & Shi, 2025

[14] Pterostichus ( Morphohaptoderus) chachi sp. nov.

Figs 4 G View Figure 4 , 5 M View Figure 5 , 26 View Figure 26

Type material.

Holotype: Hubei • ♂, labeled “ China, W Hubei, 20. V. – 7. VI., DASHENNONGJIA mts. , 31.5 N 110.3 E, 2700 m, Jaroslav Turna leg., 2005. ” ( CRS) GoogleMaps . Paratypes (a total of 4 ♀): Hubei • 2 ♀, the same data as holotype ( CRS) GoogleMaps ; • 2 ♀, labeled “ Hubei Province, Shennongjia, Jinhouling , 2500 m, pitfall trap, 2013. VIII. 15, Hao Huang leg. ” [in Chinese] ( IZAS) .

Diagnosis.

Very small-sized species for the subgenus ( BL = 4.6–4.7 mm), the smallest known Pterostichus species in China; elytra with linear microsculpture in females; antennae moniliform, antennomere 3 with accessory on apical half; pronotum slightly cordate, maximum width near apical third; basal foveae finely punctate, with faintly defined sulci; parascutellar pore absent; elytral interval 3 with three setigerous pores, the basal one adjacent to stria 3, the other two adjacent to stria 2; interval 1 with one setigerous pore near apex, adjacent to stria 1; fifth tarsomeres with two pairs of setae ventrally.

Comparisons.

The new species, P. chachi sp. nov., is very special within the subgenus Morphohaptoderus and different from all other known species of the subgenus by the following distinctive characteristics: (1) Body size very small, BL = 4.6–4.7 mm, being the smallest species of the subgenus as well as the smallest one of Pterostichus from China; (2) elytra without parascutellar pore (Fig. 4 G View Figure 4 ); (3) interval 3 with three setigerous pores, the first adjacent to stria 3, the other two adjacent to stria 2 (Fig. 26 A View Figure 26 ); (4) interval 1 with one setigerous pore near apex (Fig. 26 B, C View Figure 26 ).

Most of the above-mentioned characteristics are either unique or relatively rare within the subgenus Morphohaptoderus , with the details elaborated as follows. The previously known smallest Pterostichus species in China was P. gongga Sciaky, 1997 , with a measured BL of 4.8–5.9 mm, which also belongs to the subgenus Morphohaptoderus . Besides P. chachi sp. nov., the parascutellar pore is absent only in two Morphohaptoderus species from Vietnam, P. unisetosus Fedorenko, 2023 , and P. glabellus Fedorenko, 2023 . Only two other species, P. toledanoi and P. xuanzhang sp. nov., both from Hubei, share a chaetotaxy on elytral interval 3 similar to that of the present new species. However, in these two species, the three setigerous pores on interval 3 are positioned relatively more posteriorly. Specifically, they are located at the basal fourth, near the middle, and the apical fourth, respectively. In contrast, in P. chachi sp. nov., these pores are more anteriorly placed, at the basal fifth, basal two-fifths, and apical third, respectively. Finally, the presence of a setigerous pore on interval 1 (Fig. 26 B, C View Figure 26 ) is unique to P. chachi sp. nov. and has never been observed in any other Pterostichus species in China.

The general habitus of the new species P. chachi sp. nov. is somewhat similar to some small-sized Morphohaptoderus from Western China, such as P. confucius Sciaky & Wrase, 1997 , P. gongga Sciaky, 1997 , and P. emei Sciaky, 1994 . But different from them by the smaller body size, distinctive chaetotaxy on elytra, and submentum with one seta on each side.

Description.

BL = 4.6–4.7 mm, BW = 1.7–1.8 mm; dorsal surface brown to dark brown, elytra slightly lighter than head and pronotum, appendages brown; elytra with linear microsculpture in females (Fig. 26 A View Figure 26 ).

Head slightly thickened, HW / PW = 0.62–0.64; frons without puncture; frontal sulci short and shallow; antennae moniliform, reaching elytral basal fourth, antennomere 3 with a few accessory setae on the entire surface of apical half; eyes relatively small, the length of tempora slightly shorter than the length of eyes; submentum with one seta on each side.

Pronotum slightly cordate, wider than length, PW / PL = 1.30–1.31, widest near apical third, posterior margin much narrower than greatest width, PBW / PW = 0.78–0.80. Anterior margin concave at middle, slightly narrower than posterior margin, PAW / PBW = 0.85–0.86; anterior angles broadly rounded, weakly projecting; lateral margins evenly arched nearly along their full length, more distinctly narrowed toward base, not sinuate before posterior angles, posterior angles obtuse-angled, with very faint denticle not projecting out. Basal foveae (Fig. 4 G View Figure 4 ) shallow and finely punctate, punctures along inner and outer sulci, as well as on intersulcate area; inner and outer sulci without well-defined boundaries; inner sulcus straight and shallow, outer sulcus very faint, hardly recognizable; a basal sulcus fine but clearly defined, long and straight, medially extending beyond the base of inner sulcus, shortly bent to the front laterally, surrounding the inner side of the setigerous pore on posterior angle; intersulcate area slightly convex; lateral channels narrow, without puncture. Pronotal disc with very faint transverse wrinkles aside median line; median line shallow; basal median area with a few punctures close to inner sulcus.

Elytra oval and flat, humeral area distinctly narrowed, lateral sides curved and expanded near middle, BW / EL = 0.68–0.69. Elytral basal border nearly straight, forming a distinct obtuse angle with lateral margin, humeral tooth small, apex faintly pointed; striae without punctures, slightly crenulate on basal third; parascutellar striole joined to apical portion of stria 1, angular base of stria 1 absent or indicated by one or two isolated punctures. Parascutellar pore absent (Fig. 4 G View Figure 4 ); elytral interval 3 with three setigerous pores, the first pore adjacent to stria 3, positioned near basal fifth, the other two pores adjacent to stria 2, near basal two-fifths and apical third respectively; interval 1 with one setigerous pore near apical sixth, adjacent to stria 1 (Fig. 26 B, C View Figure 26 ); umbilical pore series on ninth interval sparse in middle, composed of 12–14 pores (5–6, 1–2, 6–7). Elytral apical margin shortly truncated, faintly denticulate at sutural angles (Fig. 26 F View Figure 26 ).

Fifth tarsomeres with two pairs of fine setae ventrally.

Male sternite without secondary sexual modification, apex of sternite VII evenly rounded.

Median lobe of aedeagus (Fig. 26 B View Figure 26 ) relatively slender; in lateral view, ventral margin bent near basal fourth, nearly straight at middle portion before apical fourth, slightly sinuate at apical fourth, apex distinctly bent to the ventral side; apical orifice relatively small, weakly turned to left side, opened to the dorsal left surface of median lobe. Ventral surface without ridge. Apical lamella thin in lateral view; narrow and relatively long in dorsal view ( AL / AW = 1.56), faintly turned to left side, gradually narrowed to apex, shaped a narrow triangle, apex rounded (Fig. 26 C View Figure 26 ); lamellar denticle very small and faint, present near basal third of left margin. Right paramere short, apex rounded and extremely small (Fig. 26 D View Figure 26 ).

Endophallus of male genitalia not studied due to restricted materials.

Gonocoxite 2 of female ovipositor small, widely crescent-shaped (Fig. 5 M View Figure 5 ), slightly obtuse apically; outer margin with two or three ensiform setae of normal size, length of the largest ensiform seta ca. 0.03 mm; dorsal margin with one ensiform seta near middle, ridged between the ensiform seta and apex of gonocoxite 2, one nematiform seta located on the apical fifth of outer surface.

Distribution.

This species is only known from Jinhouling in Shennongjia, Hubei Province. It is distributed at a high altitude of about 2500 m.

Etymology.

The scientific name of the new species is derived from Qu Yuan’s work “ Ai Ying ”: 惨郁郁而不通兮 [Can Yu Yu Er Bu Tong Xi], 蹇侘傺而含戚 [Jian Cha Chi Er Han Qi]. This couplet can be translated as: My mood is heavy with melancholy. I stand alone, filled with sorrow. It describes the poet’s sorrowful mood after the fall of the capital of Chu and the humiliation of King Chu by the people of Qin. Chachi (侘傺) describes a scene of standing alone in dejection in the poem. As a specific name, chachi implies that the new species is very rare, with only one sex having been discovered. The name is treated as a noun in apposition.