Zethus (Zethastrum) bakeri Giordani Soika 1995
Creators: name: Yeh, Wen-Chi
name: Barthélémy, Christophe
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Eumenidae
Zethus
Zethus bakeri

description: Zethus (Zethastrum) bakeri Giordani Soika, 1995
Zethus bakeri Giordani Soika, 1995: 92 —“ Singapore ” (holotype, ♀, MSNV).
Zethus malayanus Gusenleitner, 2010: 704–705, figs 15–19—“ Perak, Cameron Highlands, Batu, Malaysia ” (holotype, ♀, OLML), “ syn. nov. ”
Material examined. SINGAPORE — 1♀, Coll. Baker; (holotype, MSNVE).
CHINA — Hong Kong • 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 (Fig. 22–26). Body black with yellowish tegula, tibia adorned outside with dense and long pale yellowish hair (Fig. 24). Clypeus broader than long, apical margin straight (Fig. 22). Tegula oval, apex slightly incurved and obtuse (Fig. 23). Propodeum nearly vertical, dorsal side shallowly foveate, both lateral and submedian carinae indiscernible, bf linear (Fig. 26). Abdominal Sg1 slim and long, four times as long as wide; Sg2 strongly petiolate with basal petiole around 1/4 as long as the segment (Fig. 25), S3 with median part of apical margin protruding backwards, forming a crescent protuberance (as in Fig. 29).
Male (Figs 27–31). Differing from female mainly in the following: Clypeus with a large yellow spot at middle, mandibles largely yellow (Fig. 28). Antenna with F3–F9 ventrally adorned with dense and long whitish hair tufts (Fig. 31), F11 bullet-shaped with apex obtusely pointed and reaching at the base of F 8 in appressed condition (Fig. 30). Tegula black, hairs of tibia not especially dense and long; both Sg1 and basal petiole of Sg2 shorter (Fig. 27).
Genitalia (Figs. 33, 35, 38, 39). Apex of genital capsule strongly curved inwards, volsellar ridge unarmed and nearly smooth. Cuspis long with apex reaching apex of genital capsule (Fig. 33), adorned with dense thin hairs on inner side. Digitus petal-shaped, largely membranous and concave on ventral side; lbd transversely triangular and adorned with many tiny sensory cones and few short hairs, ldd finger-like and curved with rounded apex (Fig. 35). Aedeagus in lateral view with lvv erect and rectangular, basally attenuating into a horn-like protuberance (Fig. 38), ap roundly curved at middle, pb very short and obtuse at apex; in ventral view, apical half of lvv expanding and rounded, ap angulately incurved at basal 1/4, pb rounded (Fig. 39).
Remarks: We examined the female holotype of Z. bakeri and compared it with high resolution images, the original description and figures of the holotype female of Z. malayanus. The result did not reveal any distinct difference separating them; hence, we confirm that Z. malayanus is a junior synonym of Z. bakeri. The Hong Kong male was compared with the description and figures of the Guangdong male of Z. malayanus given by Nguyen & Xu (2017) and there was no convincible evidence either that could differentiate the males from each other.
Distribution: Singapore, Malaysia, Vietnam (Nguyen & Carpenter, 2016), China (Guangdong, Hong Kong).
description: Published as part of 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), pp. 520-532 in Zootaxa 5339 (6) on pages 529-531, DOI: 10.11646/zootaxa.5339.6.2, http://zenodo.org/record/8313719