Zaitzevia disparilis, 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 disparilis sp. nov.

Figs 3 A, B , 8 A – C , 12 A – C

Material examined.

(822 exs) Holotype: China • ♂ ( IAECAS): “ China: Shaanxi, \ Foping County \ Gaozhuanggou | 33°34′18″N, 107°57′56″E \ 1035 m, 2019. VI. 21 \ Leg. Tong ” . Paratypes: China, Shaanxi • 6 ♂♂, 3 ♀♀, 32 exs ( IAECAS), the same data as holotype • 3 exs ( NMW): “ China: Shaanxi, 1. 6. 1998 \ 130 km SE Baoji, ca. 1 100 m \ Taibai Shan Forest Park \ leg. M. Wang ( CWBS 307 ) ” • 10 exs ( NMW): “ China: Shaanxi, 7. 6. 1998 \ 7 km SE Liuba, ca. 1300 m \ Taoyuanpu Village env. \ leg. M. Wang ( CWBS 316 ) ” • 1 ♀ ( CPE): “ China: Shaanxi, Qin Ling Shan \ 108.49E, 33.55N [coordinates obviously unprecise], River Valley \ 40 km S Xian, Autoroute km 50 \ River bank, 1200 m \ 31. 08. 1995, leg. A. Pütz ” • 11 exs ( CBC, NMW): “ China, 17. – 22. VI. \ Shaanxi prov. 1991 \ Hua Shan peak env. \ 100 km E of Xi’an \ Z. Kejval lgt. ” .

Additional material.

China, Gansu • 1 ♀ ( NMW): “ China: Gansu, 15. 6. 1998 \ Wen Co., Bikou env. \ Dong Gou River , ca. 950 m \ leg. M. Wang ( CWBS 326 ) ” ; Anhui • 437 exs ( NMW): “ China: Anhui, Dabie Shan \ 40 km N Yuexi, 5. 11. 1997 \ env. Gui Xing Di , 800 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 295 ) ” • 220 exs ( NMW): “ China: Anhui, Dabie Shan \ 20 km N Yuexi, 6. 11. 1997 \ env. Shi Guan , 900 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 296 ) ” • 27 exs ( NMW): “ China: Anhui, Dabie Shan \ 20 km N Yuexi, 6. 11. 1997 \ env. Shi Guan , 950–1000 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 297 ) ” • 82 exs ( NMW): “ China: Anhui, Dabie Shan \ 50 km NW Yuexi, 7. 11. 1997 \ Huang Liyan / Baojia, 1050 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 298 ) ” • 8 exs ( NMW): “ China: Anhui, Dabie Shan \ 50 km NW Yuexi, 8. 11. 1997 \ Huang Liyan / Baojia, 1050 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 299 ) ” • 17 exs ( NMW): “ China: Anhui, Dabie Shan \ 25 km N Yuexi, 9. 11. 1997 \ env. Shi Guan , 1000 m \ leg. Schönmann [respectively: “ leg. M. Wang ”] ( CWBS 301 ) ” ; Hunan • 16 exs ( NMW): “ China, NW-Hunan 1993 \ Wulingyuan, N Dayong \ Zangjiajie [ Zhangjiajie ], 30. 10., 450 m \ leg. Schönmann (4) [ CWBS 23 ] ” • 12 exs ( NMW): “ China, NW-Hunan 1993 \ Wulingyuan, N Dayong \ Suoxiyu , 31. 10., 400 m \ leg. Schönmann (5) [ CWBS 24 ] ” ; Guizhou • 1 ♀ ( NMW): “ China: Guizhou, Zunyi Pref. \ 25 km NE Zunyi City \ ca. 1000 m, 3. 8. 1997 \ leg. M. Wang ( CWBS 278 ) ” • 1 ♀ ( NMW): “ China: Guizhou, Leishan Co. \ SE Kaili, NE Leishan \ Leigong Shan , E - slope \ 26°26.11'N, 108°16.08'E \ Wunang River \ 13. 6. 2001, ca. 9-00 m [sic] \ leg. Schillhammer & Wang ( CWBS 432 ) ” .

Differential diagnosis.

Zaitzevia disparilis sp. nov. is a rather small species ( BL 1.46–2.00 mm), characterized by the often remarkably unequal size of the elytral punctures, by the elytral carinae being located on intervals 5–7, and the conspicuous sclerotizations of the endophallus.

In habitus and body size it somewhat resembles Z. tsushimana from Jilin, which is on average longer ( BL 1.8–2.2 mm) and differs, among other characters, in the longer median pronotal sulcus (see Jäch and Boukal 1995: fig. 59 [as “ Zaitzevia sp. ( Jilin) ”]; Iwata et al. 2022: fig. 3 G), the flat elytral intervals (only rarely flat in Z. disparilis sp. nov.) and the structure of the endophallic sclerotizations.

Description.

Male ( holotype). BL 1.8 mm, BW 0.8 mm. Body elongate obovate. Dorsum and ventral side dark brown, antennae yellowish brown. Legs dark brown but tarsi reddish brown. Labrum wider than long. Basal 0.33 microreticulate, distal 0.67 densely punctate and pubescent, with fringe of long setae laterally. Clypeus and frons densely pubescent and sparsely granulate.

Pronotum ( PL 0.55 mm, PW 0.6 mm) broadest at base, gradually narrowing anteriad, lateral margin narrowly rimmed. Anterior corners acute, slightly produced, posterior corners rectangular. Disc smooth and shiny, punctures sparser than on lateral parts. Areas near anterior and posterior corners coarse, densely and finely granulate. Median groove moderately wide, extending from basal 0.2–0.6. Lateral carinae present in basal 0.4.

Elytra ( EL 1.25 mm, EW 0.8 mm) subparallel in basal 0.67, distal 0.33 distinctly attenuate. Strial punctures in basal 0.5 unequal in size and depth, separated by 1.0–1.5 × their diameters, being deepest in the third stria, becoming smaller and shallower on declivity (separated by 2–3 × their diameters); striae not reaching elytral apex. Elytral intervals weakly convex, smooth and shiny, with only a few small setal punctures; interval 4 very slightly more convex than intervals 1–3; intervals 5–7 carinate (due to fusion of elytral striae 5 and 6), carina on interval 5 extending from basal 0.1 to apex, carinae on intervals 6 and 7 complete, merging at basal ~ 0.1. Elytral apices narrowly conjointly rounded.

Prosternal disc coarse, sparsely punctate and pubescent, lateral areas densely tomentose. Prosternal process gradually narrowed in basal 0.8, then distinctly narrowed in distal 0.2, apex narrowly rounded. Disc of prosternal process sparsely punctate and pubescent. Metaventrite shiny, with a few larger elongate punctures, slightly impressed medially; median sulcus present in basal 0.7, distinctly narrowed from base to apex. Lateral areas densely pubescent. Posterior margin of metaventrite impressed, with two large impressions behind of mesocoxae, and a row of middle-sized punctures in front of metacoxae.

Disc of ventrite I flat, smooth, and shiny, with only a few punctures, and a transverse row of few granules posteriorly; anteriorly impressed and wrinkled; laterally bordered by strong admedian carinae. Middle of ventrites II – IV and basal 0.33 of ventrite V smooth and shiny, with only a few punctures. Distal 0.67 of ventrite V densely pubescent and granulate. Lateral areas of ventrites I – IV densely pubescent. Lateral margins of ventrite V fringed with short spines; apex subtruncate, lateral apical corners covered by a brush of stiff setae.

Aedeagus. 0.8 mm long, elongated, and cylindrical. Penis ~ 2.2 × as long as phallobase. Penis gradually broadened in basal 0.25, then almost subparallel to apical 0.25, then distinctly narrowed toward cuspidal apex. Sclerotizations of endophallus in median part of penis (basal 0.3–0.7) resembling a “ bowknot ” (in ventral / dorsal view), consisting of a pair of ovoid structures, each with an apical curved tooth and a moderately long, thin basal rod. Parameres short, clinging to penis, reaching apical 0.45 of penis.

Females. Disc of metaventrite more evenly convex or evenly flattened than in males, without larger punctures or granules; ventrite I less impressed anteriorly, without distinct wrinkles; ventrite V very similar to male, but more sparsely granulate; apex subtruncate or weakly rounded.

Measurements.

(type specimens) Males: BL 1.68–1.90 mm ( n = 10), BW 0.75–0.80 mm ( n = 7); females: BL 1.80–1.96 mm ( n = 10), BW 0.75–0.80 mm ( n = 3).

Including the additional material, the BL of Z. disparilis is 1.46–2.00 mm. The smallest male ( Anhui, CWBS 299 ) is 1.50 mm long, the smallest female ( Anhui, CWBS 301 ) 1.46 mm, and the largest female ( Hunan, CWBS 24 ) 2.00 mm.

Distribution.

Anhui, Gansu, Guizhou, Hunan, Shaanxi. Remarkably, there are no records from Hubei at present.

Etymology.

The name is derived from the Latin adjective disparilis (disparate, different, unequal), referring to the differently sized and variably deep impressed elytral punctures.

Remarks.

We think that all specimens recorded from these five provinces belong to the same species, but due to the morphological variability (e. g., body length, size and depth of elytral punctures, granules of elytral intervals sometimes reaching elytral base) we do not designate the specimens from Anhui, Gansu, Guizhou, and Hunan as paratypes. Confirmation of the conspecific molecular data would be highly desired, especially in case of the material from Gansu and Guizhou from where only females are currently known.

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 8. Zaitzevia disparilis 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.