Zaitzevia hybrida, Bian & Jäch, 2025

Bian, Dong-Ju & Jäch, Manfred A., 2025, The species of the genus Zaitzevia Champion, 1923 (Coleoptera, Elmidae) from Shaanxi Province, China, ZooKeys 1264, pp. 129-157 : 129-157

Zaitzevia hybrida sp. nov.

Figs 3 C, D , 9 A – C , 12 D – F

Material examined.

(45 exs) Holotype: China • ♂ ( IAECAS): “ China, Shaanxi, Qingling \ Ningshan County | Yaowangtang , 1286 m \ 2005.6. 10, Wangm [leg. Wang Miao] ” . Paratypes: China, Shaanxi • 4 ♂♂, 3 ♀♀ ( IAECAS): “ China-Shaanxi \ Zhouzhi County I. [leg.] W [ Wang] | Houzhenzi ca. 1200 m \ 2. VI. 1998 ” [ CWBS 308 ] • 8 ♂♂, 8 ♀♀ ( NMW): “ China: Shaanxi, 2. 6. 1998 \ Zhouzhi County, ca. 1200 m \ 2 km W Houzhenzi Nat. Res. \ leg. M. Wang ( CWBS 308 ) ” • 1 ♀ ( NMW): “ China: Shaanxi, 4. 6. 1998 \ Foping County, ca. 1 300 m \ 5 km S Longcaoping \ leg. Wang ( CWBS 312 ) ” • 2 ♂♂, 6 ♀♀ ( NMW): “ China: Shaanxi, 6. 6. 1998 \ Ningshan Co., ca. 1 500 m \ 10 km NE Xunyangba \ leg. M. Wang ( CWBS 315 ) ” • 1 ♂ ( NMW): “ China, 17. – 22. VI. \ Shaanxi prov. 1991 \ Hue Shan peak env. \ 100 km E of Xi’an \ Z. Kejval lgt. ” .

Additional material.

China, Gansu • 2 ♂♂ ( NMW): “ China: Gansu, 13. 6. 1998 \ Wen Co., ca. 1100 m \ 4 km N Shangdan Village \ leg. M. Wang ( CWBS 322 ) ” • 1 ♀ ( NMW): “ China: Gansu, 14. 6. 1998 \ Wen Co., ca. 1 150 m \ 1 km N Shangdan Village \ leg. M. Wang ( CWBS 323 ) ” ; Sichuan • 2 ♂♂ ( NMW): “ China: Sichuan, 13. 6. 1996 \ W Ya’an, 20 km W Tianquan \ Dayuxi stream , 1200 m \ leg. Ji & Wang ( CWBS 235 ) ” • 1 ♀ ( NMW): “ China: Sichuan, 29. 7. 1998 \ Mao Xian Co., Jiuding Shan \ 10 km NE Mao Xian , ca. 1950 m \ Schönmann, Ji, Wang ( CWBS 336 ) ” • 1 ♀ ( NMW): “ China: Sichuan, 30. 7. 1998 \ Mao Xian Co., Jiuding Shan \ 20 km NE Mao Xian , ca. 1650 m \ Schönmann, Ji, Wang ( CWBS 337 ) ” • 1 ♀ ( NMW): “ China: Sichuan, 30. 7. 1998 \ Mao Xian Co., Jiuding Shan \ 15 km NE Mao Xian , ca. 1950 m \ Schönmann, Ji, Wang ( CWBS 338 ) ” • 1 ♀ ( NMW): “ China: Sichuan, 30. 7. 1998 \ Mao Xian Cty., Jiuding Shan \ 6 km NE Mao Xian , ca. 1750 m \ Schönmann, Ji, Wang ( CWBS 340 ) ” ; Yunnan • 1 ♂ ( NMW): “ China-Yunnan 24. – 29.6. \ 50 km N Lijiang, 1993 \ Yulongshan Nat. Res. \ E. Jendek & O. Sausa leg. ” • 3 ♂♂, 6 ♀♀ ( NMW): “ China-Yunnan 14. – 21.6. \ 100 km W Baoshan, 1993 \ Gaoligongshan Nat. Res. \ E. Jendek & O. Sausa leg. ” .

Differential diagnosis.

Zaitzevia hybrida sp. nov. is a small species ( BL 1.50–1.86 mm), which differs significantly from all other species described in the genus Zaitzevia in possessing characters that are typically found in Zaitzeviaria Nomura, 1959 , i. e., elytra with only two instead of three carinae, and elytral the plastron being confined to the area between the lateral margin and interval 7 (therefore not reaching interval 5). This species is furthermore characterized by the enlarged male protibiae.

Description.

Male ( holotype). BL 1.7 mm, BW 0.7 mm. Dorsum dark brown, ventral side and legs reddish brown except tarsi. Antennae, mouth parts, and tarsi yellowish brown.

Labrum wider than long, anterior margin not emarginate, basal 0.5 microreticulate, distal 0.5 smooth and shiny, sparsely punctate and pubescent laterally. Clypeus and frons densely punctate and pubescent.

Pronotum ( PL 0.5 mm, PW 0.6 mm) broadest at basal 0.3, slightly narrowed posteriorly and distinctly attenuate anteriorly, posterior corners rectangular. Disc smooth and shiny, densely pubescent shallowly punctate. Areas near anterior and posterior corners coarsely granulate. Median groove short and shallowly impressed, extending from basal 0.4–0.7. Lateral carinae present in basal 0.4, joined by a distinct mesial groove. Base of pronotum with a group of granules medially.

Elytra ( EL 1.2 mm, EW 0.75 mm) broadest at basal 0.67, slightly narrowed anteriorly and distinctly attenuate posteriorly, apices narrowly conjointly rounded. Strial punctures large in basal 0.5, separated by 0.5–1.0 × their diameters; punctures becoming smaller and well separated in distal 0.5. Intervals smooth and shiny, each with a row of setae; intervals 7 and 8 distinctly carinate, extending from base to declivity. Base of elytra narrowly granulate. Lateral margins distinctly denticulate.

Prosternum coarsely punctate and pubescent. Prosternal process distinctly narrowed from base to narrowly rounded apex; lateral margin distinctly rimmed. Disc convex, coarse, sparsely punctate and pubescent. Metaventrite slightly and broadly impressed, disc smooth and shiny, sparsely punctate and pubescent; median groove extending from base to anterior 0.1, gradually narrowed towards apex; lateral area densely pubescent and sparsely granulate; each side with two large elongate pits behind mesocoxae and a row of large punctures is in front of metacoxae.

Disc of ventrite I convex, largely smooth and shiny, sparsely punctate; along anterior margin slightly impressed with densely arranged, deeply impressed grooves; laterally bordered by strong admedian carinae. Discs of ventrites II – IV and basal 0.2 of ventrite V smooth and shiny; sparsely punctate and pubescent. Lateral sides of ventrites I – IV densely pubescent and sparsely granulate. Apex of ventrite V subtruncate, lateral apical corners rounded, bearing some stiff setae. Protibia distinctly enlarged.

Aedeagus. 0.69 mm long, elongate. Penis ~ 3.5 × as long as phallobase, very slightly asymmetrical, subparallel in basal 0.4, then gradually narrowed; apex subacute. Sclerotizations of endophallus in basal 0.5 of penis, consisting of a pair of elongate ovoid structures (in basal 0.3–0.5) and a pair of long thin contiguous basal rods. Parameres short, reaching apical 0.33 of penis.

Females. Protibiae not distinctly enlarged. Sexual dimorphism of metaventrite and abdominal ventrites poorly developed; ventrite I anteriorly less strongly impressed and less distinctly wrinkled; apex of ventrite V variable in both sexes: weakly emarginate, subtruncate or weakly rounded.

Measurements.

Males: BL 1.50–1.86 mm ( n = 18), BW 0.75–0.80 mm ( n = 6); females: BL 1.68–1.86 mm ( n = 17), BW 0.75–0.80 mm ( n = 3).

Distribution.

Gansu, Shaanxi, Sichuan, Yunnan,? Himalaya.

Comparison with Himalayan specimens (Himachal Pradesh, Nepal, Bhutan) indicates that Zaitzevia hybrida seems to occur there as well. However, it will be necessary to confirm this assumption by molecular data.

Variability.

Due to the morphological variability of the material examined (e. g., protibiae, elytral intervals, aedeagi), we do not designate the specimens from Gansu, Sichuan, and Yunnan as paratypes. Examination by molecular methods would be highly desired. The single male from Yulongshan ( Yunnan) is 1.68 mm long and its aedeagus measures 0.69 mm; its external morphology agrees quite well with specimens of Z. hybrida from Gansu, Shaanxi, and Sichuan. However, the three males from Gaoligongshan ( Yunnan) are 1.46–1.64 mm long, and their aedeagi are slimmer and shorter ( 0.61–0.63 mm) than in the males from the other populations ( 0.68–0.70 mm). Furthermore, they differ externally in the distinctly less densely punctate elytral striae and the flatter elytral declivity; genetically, they differ in the ovoid sclerotization of the endophallus being distinctly smaller. Therefore, these nine specimens from Gaoligongshan ( Yunnan) listed above may well represent a different species, which should be confirmed by DNA sequencing.

The enlargement of the male protibiae is obviously allometric. In larger specimens the tibiae are disproportionately larger than in smaller ones.

As in other species of the genus Zaitzevia , the size and number of the elytral punctures, and especially the width and convexity of the elytral intervals 2–6 are quite variable; these intervals can be flat, moderately convex or carinate, at least in the anterior 0.33. In some specimens, the elytral apices are separately rounded.

The shape of the aedeagus of Z. hybrida is normally symmetrical; in the holotype it is hardly noticeably asymmetrical, and in the two males from Gansu ( CWBS 322 ), one is very slightly asymmetrical and the other one even more distinctly so.

Etymology.

The epithet is derived from the Latin noun hybrida (hybrid) referring to the fact that Zaitzevia hybrida and a number of other undescribed species from China and the Himalaya combine diagnostic characters of Zaitzevia and Zaitzeviaria .

Remarks.

At a first glance, Zaitzevia hybrida seems to belong to the genus Zaitzeviaria , based on the small size and the elytral carinae being located on intervals 7 and 8. On the other hand, it shares a number of characters with Zaitzevia . Therefore, and in the absence of any molecular data, we have decided to place this species tentatively in the genus Zaitzevia . For further information, see the Discussion.

Figures

Figure 3. Habitus. A, B. Zaitzevia disparilis sp. nov.; holotype, male; C, D. Z. hybrida sp. nov., holotype, male; A, C. Dorsal view; B, D. Ventral view.

Figure 9. Zaitzevia hybrida sp. nov., holotype, male; A. Pronotum; B. Prosternum; C. Metaventrite and abdominal ventrites.

Figure 12. Aedeagus. A – C. Zaitzevia disparilis sp. nov., holotype, male; D – F. Z. hybrida sp. nov., paratype, male; A, D. Ventral view; B, E. Dorsal view; C, F. Lateral view.