Zethus (Zethus) angulatus Nguyen & Carpenter, 2016

Yeh, Wen-Chi & Barthélémy, Christophe, 2023, A taxonomic study on the genus Zethus Fabricius from Hong Kong, with proposal of a new synonym (Hymenoptera: Vespidae: Eumeninae), Zootaxa 5339 (6), pp. 520-532 : 521-522

Zethus (Zethus) angulatus Nguyen & Carpenter, 2016

Zethus angulatus Nguyen and Carpenter, 2016: 27–28 , 31(key), figs. 13-18, ♁, ♀ —“ Vietnam, Bac Vang ranger station, Na Hang natural reserve, Na Hang , Tuyen Quang, 22°20’52.6”N, 105°25’49”E, ca. 120 m ” (holotype, ♁, IEBR).

Reports from Hong Kong: Barthélémy, 2012: 14–15, figs 60–63, (as Zethus sp. ); Li et al., 2019: 162, figs 127– 129, (as Z. dolosus , misidentification).

Material examined. CHINA — Hong Kong • 2♁; Pak Sha O; 22°26'59"N, 114°19'04"E, alt. 70 m; C. Barthélémy leg.; reared; 16 Apr. 2016 ( CBC) • 3♁; ditto; 17 Apr. 2016 ( CBC) • 1♁; ditto; 23 Apr. 2016 ( CBC) • 1♀; ditto; 24 Apr. 2016 ( CBC) • 1♀; Hok Tau ; 22°29'25.31"N, 114°11'0.14" E; W.-C. Yeh leg.; hand net; 06 Jun. 2006; ( FACT) .

Diagnostic description. Female ( Figs 3, 4 , 7–11 ). Body black with yellow spots on dorso-inner margin of antennal socket and apical margin of T1; tegula dark reddish brown. Body surface generally smooth and shining, dull on propodeum, sparsely punctate throughout, only densely and coarsely punctate on head ( Fig. 8 ), dorsal side of pronotum and T1, and transversely costate on lateral side of pronotum and posterior depression of propodeum; lateral side of propodeum foveate on upper half and coriaceous on lower half ( Fig. 11 ). Clypeus apically truncate with two small and obtuse teeth, space between the teeth depressed with a middle ridge either distinct or obscure. Mandible with three closely set teeth on inner margin, middle tooth adjoining basal tooth; inter-antennal area with a smooth and Y-shape ridge ( Fig. 7 ). Tegula oval, posterior lobe triangular and straight ( Fig. 10 ), apex obtuse and reaching well beyond parategula (as in Fig. 2 ). Propodeum with lateral carina weak, submedian carina distinct on basal half of propodeum and bf triangular ( Fig. 9 ). Metasoma with Sg1 three times as long as wide ( Fig. 4 ), slightly shorter than Sg2; T2 weakly depressed before apical margin with short apical lamella obliquely erect, S2 weakly angulate in profile, apical lamella shorter than T2; T3 depressed medially, with apical lamella flat, smooth and long, occupying apical 1/3 of T3; S3 with short and narrow apical lamella only presenting medially on apical margin as an indistinct and smooth flange.

Male ( Figs 1, 2, 5, 6 ). Differing from female mainly in the following: Clypeus rectangularly notched apically with two large and obtuse teeth ( Fig. 1 ); mandible with three well-separated teeth on inner margin, basal tooth merged with basal angle and forming a rectangular plate, middle tooth separated from basal tooth by a broad notch. F11 slightly curved ( Fig. 5 ) and bullet-shaped in ventral view ( Fig. 6 ), apex rounded and reaching at the base of F 8 in appressed condition.

Genitalia ( Figs 32 , 34, 36, 37 ). Cuspis short and adorned with dense denticles on outer side; lbd deeply curved and saddle-shaped, adorned with many tiny sensory cones and few short hairs, ldd slender and blade-like, attenuate towards and pointed at apex ( Fig. 32 ). Volsellar ridges adorned with a pack of four thick setae at dorsal margin and a row of 12 setae at ventral margin ( Fig. 34 ). Aedeagus in lateral view with lvv erect and rectangular, basal 1/2 distinctly higher than apical 1/2 ( Fig. 36 ), ap robust and roundly curved at basal 1/3, pb strongly attenuate towards apex and, in ventral view, elongate and triangular, with pointed apex ( Fig. 37 ).

Remarks: Zethus angulatus was first recorded from China by Wang et al. (2019) in Guangxi and Guangdong; hence, its existence in Hong Kong is not exceptional. Li et al. (2019) misidentified this species as Z. dolosus and mentioned it was common in Hong Kong. The nesting habit has been described in detail by Barthélémy (2012). This species is easily distinguished from Z. dolosus by many distinct morphological features, including the shorter and more swollen petiole, more smoothly curved profile of S2 and unmarked clypeus in male. The configuration of male genitalia is similar to that of trimaculatus -group shown by Yeh & Lu (2017).

Distribution: Vietnam, China (Guangxi, Guangdong and Hong Kong).

Figures

FIGURES 1–6. Zethus angulatus, 1, 2, 5, 6, male; 3, 4, female. 1, clypeus and mandibles; 2, mesosoma in dorsal view; 3, lateral habitus; 4, metasoma in dorsal view; 5, 6, antenna.

FIGURES 7–11. Zethus angulatus, female. 7, head in frontal view; 8, head in dorsal view; 9, propodeum in dorsal view; 10, tegula; 11, propodeum in lateral view. bf, basal fovea of propodeum.

FIGURES 32–33. Male genitalia of Zethus in ventral view. 32, Z. angulatus; 33, Z. bakeri. crv, volsellar ridge; cu, cupis; di, digitus; go, gonocoxite; lbd, basal lobe of digitus; ldd, distal lobe of digitus.

FIGURES 34–39. Male genital structures of Zethus, 34, 36, 37, Z. angulatus; 35, 38, 39, Z. bakeri. 34 & 35, left volsella, inner view; 36 & 38, aedeagus in lateral view; 37 & 39, aedeagus in ventral view. ap, basal apodeme of aedeagus; lvv, ventral lobe of penis valve; pb, basal plate of aedeagus.