Euconnus vertexalis Li & Yin 2021, sp. nov.

Euconnus (s. str.) vertexalis sp. nov.

(Fig. 1)

Type material (1 ex.). Holotype: CHINA: Ƌ, labeled ‘ Yunnan, Lincang City, Mt. Tangli, 24°01'18''N, 99°14'20''E, 1758 m, 2020.ii.25, with Odontotermes termites, sifted, Ji-Shen Wang leg., ủfflfiȏȑḿṫḗflŝḭffi’ (SNUC).

Diagnosis. Male. Body length approximately 1.40 mm; length/width of antennomere 11 1.0; vertex with broadly transverse cavity, its posterior margin greatly raised, with flame-like trichome on posterior wall of cavity; elytral length/width 1.39; mesotibia with preapical tuft of setae; aedeagus stout and transverse in dorso-ventral view, median lobe with ventroapical lobe broadened, split at middle, apical lobe roundly triangular.

Description. Male. Body (1A) moderately stout and convex, length (combined length of head, pronotum and elytra) 1.39 mm; coloration uniformly red-brown, mouthparts and tarsi paler. Head (Figs 1B, C; 2A) elongate suboval, broadest across eyes, length from anterior margin of clypeus to posterior margin of vertex 0.33 mm, width across eyes 0.28 mm; vertex and frons confluent, convex; supraantennal tubercles moderately raised; eyes small, weakly convex; tempora in dorsal view 2.8× as long as eyes. Punctures on vertex and frons small and inconspicuous; setae long and dense, suberect; tempora with setae much longer and denser bristles.Antennae short, length 0.52 mm; antennomeres 1 and 2 each strongly elongate, antennomeres 3–7 each moniliform, antennomere 8 moderately transverse, antennomeres 9 and 10 each wider than 8, strongly transverse, antennomere 11 semi-ovoid, length/width 1.0. Pronotum in dorsal view subtrapezoidal, broadest at basal two-fifths, length along midline 0.33 mm, maximum width 0.31 mm; anterior margin nearly straight, sides weakly rounded at basal two-fifths, nearly straight and parallel in posterior third, posterior corners rounded; posterior margin slightly curved at middle and bent anterad at each side in front of humerus; pronotal base with two pairs of very small and shallow pits, area between inner pair of pits lacking carina, lacking sublateral carinae. Punctures of pronotal disc fine, inconspicuous; setae similar to those of head, moderately dense, suberect, disc and sides of pronotum each with sparse and dense bristles. Elytra together suboval and slightly flattened, broadest at middle, length along suture 0.75 mm, maximum width 0.54 mm, length/ width 1.39; basal impressions shallow but distinct, humeral calli absent; apices separately rounded. Punctures on elytral disc similar to those of head and pronotum; setae moderately long and dense, suberect. Legs moderately long and slender; preapical portion of mesotibia with small tuft of setae. Aedeagus (Fig. 1D, E) stout, dorso-ventrally transverse, length 0.25 mm, median lobe in ventral view with apical plate roundly triangular, ventroapical lobe dorso-ventrally broad, split at middle; parameres relatively short, each with one long apical seta, lacking subapical setae.

Female. Unknown.

Comments. The genus Euconnus Thomson comprises more than 2470 species worldwide (Newton 2020), and is represented in China by 22 species (Li et al. 2019). A majority of the Chinese species (15 spp.) occurs in Taiwan, three species were described from Fujian, three from Chongqing, and one from Anhui. The new species described here shares with E. (Euconophron) alesi Vit from Fujian a modified male head, but can be readily separated by the different position and structure of the cephalic modification. Euconnus alesi has a modified frons formed by a narrow frontal projection, and a medially divided clypeus (Vit 2011), while E. vertexalis sp. nov. has a modified vertex and an undivided clypeus. Following the revised diagnosis of Euconophron given by Jałoszyński (2017), the placement of E. alesi in this subgenus need to be re-evaluated, pending further examination of the type material. Furthermore, the new species differs from E. alesi and all other Chinese species, except for E. hepingi Makhan and E. (Napochus) schenklingi Reitter, which were known only from females, by the unique form of the apical lobe and ventroapical lobe of the median lobe of the aedeagus, which in general is also of a highly distinctive, transverse form. Euconnus hepingi Makhan from Chongqing has a much larger body size (2.0 mm) (Makhan 2005), and E. schenklingi Reitter has much less clubbed antennae (Reitter 1913), and thus may be easily distinguished from E. vertexalis sp. nov.

Distribution. China: Yunnan.

Etymology. The new specific epithet refers to the male cephalic modification of the new species.