Holotype. China – Zhejiang Prov. • ♂; glued on a card with two labels as follows: “China: Zhejiang Prov., Zhuji City, Majian Town, Near Longmen, 29.76°N, 119.89°E, 700–1000 m, 27.IX.2023, Tie-Xiong Zhao leg.” “HOLOTYPE: Paederuszhaoi sp. n., Yang & Peng des. 2024” [red handwritten label]; SNUC. Paratypes. Zhejiang Prov. • 3 ♂♂, 2 ♀♀; Zhuji City, Majian Town, Near Longmen, 29.76°N, 119.89°E, 700–1000 m, 27.IX.2023, Tie-Xiong Zhao leg; SNUC.

Measurements (in mm) and ratios: BL 9.99–10.42, FL 4.65–4.78, HL 1.41–1.57, HW 1.56–1.82, AnL: 3.00–3.33; PL: 1.54–1.64; PW: 1.67–1.82; EL: 1.02–1.10; EW: 1.57–1.64; AW: 1.64–1.79; AL: 2.24–2.29; HL/HW: 0.85–0.92; HW/PW: 0.88–1.00; HL/PL: 0.88–0.91; PL/PW: 0.95–1.00; EL/PL: 0.66–0.68; diameter of eye: 0.33–0.37.

Habitus as in Figs 1F, 12. Coloration: head and abdomen black; antennae light brown, sometimes antennomeres 4−8 infuscate; pronotum red; elytra black with distinctly bluish hue; legs with brown femora, and with brown to light brown tibiae and tarsi.

Head (Fig. 1F) transverse, widest across eyes; punctation coarse and sparse; interstices glossy. Eyes distinctly convex. Antennae slender, antennomere 4 approximately 3.2 times as long as broad and antennomere 10 1.7 times as long as broad.

Pronotum (Fig. 1F) weakly transverse or as long as broad, strongly convex in cross section; punctures sparser and slightly finer than on head.

Elytra (Fig. 1F) trapeziform; punctation distinctly coarse, well-defined, and dense. Hind wings reduced. Metatarsomere I as long as combined length of metatarsomeres II and III.

Abdomen broader than elytra; punctation dense; interstices with distinctly transverse microsculpture; posterior margin of tergite VII without palisade fringe.

Male. Mandibles (Fig. 7B) each apically with small bifid molar tooth. Labrum (Fig. 7B) with shallowly concave anterior margin, and with V-shaped median excision. Posterior margin of tergite VIII (Fig. 7E) convex; sternite VII unmodified; sternite VIII (Fig. 7F) with deep posterior excision, this excision approximately 0.4 times as long as sternite VIII; aedeagus as in Fig. 7G–I, ventral plate weakly asymmetric and apically concave in ventral view; apically acute dorsal plate of distinctive shape and nearly reaching apices of parameres; parameres distinctly asymmetric, apically curved in lateral view and acute in ventral view; internal sac with three distinctive sclerotized spines and with one additional dark membranous structure.

Female. Left mandible (Fig. 7A) with apically bifid molar tooth; right mandible (Fig. 7A) with single-pointed middle tooth. Labrum (Fig. 7A) with U-shaped median excision and with broad lateral projection on either side, as well as small projection on either side of median excision. Tergite VIII (Fig. 7C) oblong, with convex posterior margin; posterior margin of sternite VIII (Fig. 7D) strongly convex.

The type locality is situated to the west of Zhuji, central Zhejiang. The specimens were collected by hand on grasses and by sweep-netting of shrubs and shaking of branches both in shrub habitats with oak and bamboo at altitudes of 700–1000 m (Fig. 13).

The species is named after Tie-Xiong Zhao, who collected the type specimens.

The external and particularly the male sexual characters leave no doubt that this species belongs to the P.biacutus group. Among the species of this group, it appears to be most closely allied to P.jianyueae Peng & Li, 2014, with which it shares the similar morphology of the aedeagus. It is distinguished from P.jianyueae by the longer antennae, particularly the morphology of the aedeagus (distinctly asymmetric parameres; shape of the internal structure), and by the shape of the female tergite VIII and sternite VIII. For illustrations of P.jianyueae see Peng et al. (2014: figs 7, 8).