Euura halo Prous, Liston & Mutanen 2025, sp. nov.

182 Euura halo Prous, Liston & Mutanen sp. nov. urn:lsid:zoobank.org:act: E9A11B4C-D445-48E4-82DC-92247F381EEF Figs 83–84, 200, 428 Diagnosis Their mostly black colouration, narrow pale band at the base of dark brown pterostigma, and particularly the lancet (18–19 serrulae; short spine like setae, apical sutures slightly or distinctly inclined basally, middle part of basal sutures strongly bent apically) distinguish the females from the other Euura. However, the superficial resemblance to some gall-making Euura is close. Male penis valve (large and basally broad valvispina, indistinct invagination between valvispina and ventroapical lobe of paravalva) is most similar to E. uda, E. freyja, and E. myosotidis. Besides external characters, penis valves of E. uda (1.3 mm; claws with small subapical tooth) and E. myosotidis (1.2–1.4 mm; broad yellowish pterostigma) are distinctly larger than in E. halo sp. nov. (1.0 mm; bifid claws and dark brown pterostigma with whitish line at base). Euura freyja penis valves are smaller (0.8–0.9 mm) and the species does not have a distinct whitish line at the base of pterostigma. Etymology The species name, a noun in apposition, refers to an optical phenomenon (produced by light interacting with ice crystals in the atmosphere) observed by AL, MM, and MP in Utsjoki in 2023 when some of the specimens of the species were collected. Type material Holotype FINLAND – Inari Lapland • ♀; Utsjoki, Allasuolu; 69.768° N, 26.184° E; 4 Jul. 2018; M. Mutanen, N. Mutanen and A. Mutanen leg.; rearing code 118/2018, ex larva Salix sp.; ZMUO, ZMUO.038878. Paratypes FINLAND – Inari Lapland • 1 ♀; same locality as for holotype; 17 Jun. 2023; A. Liston leg.; SDEI, DEI-GISHym81435 • 1 ♂; same locality as for holotype; 20 Jun. 2023; A. Liston, M. Mutanen and M. Prous leg.; ZMUO, ZMUO.067421. – Northern Ostrobothnia • 1 ♂; Kiiminki; 65.1478° N, 25.8383° E; 14 May 2023; M. Mutanen leg.; ZMUO, ZMUO.077412. Description Female Body 4.3–4.4 mm. Colour mostly black. Labrum pale; labial and maxillary palps brown; mandibles reddish-brown at apex, pale at base; clypeus ventrally pale; supraclypeal area black or pale; temples and orbits ventrally, dorsally and posteriorly somewhat brown; legs more or less brown or pale, except coxae basally and tarsi apically black; femora pale to largely black; pronotum posteriorly or posteriorly and centrally extensively pale; tegula pale; pterostigma and costa dark brown with whitish line at base of pterostigma; hypopygium, valvifer 2, and terga 9–10 pale; all sterna and terga laterally more or less pale or pale colour increasing gradually from sternum 5 and tergum 5 laterally; cerci pale. Clypeus shallowly emarginate; frontal area between antennae rather flat, not distinctly angulate (approaching “ Amauronematus - type ”); postocellar area about 1.8–2.5 times as broad as long; antenna slightly shorter than costa; mesepisternum smooth; claws bifid, subapical tooth shorter than apical; valvula 3 in dorsal view slightly tapering, narrow, without invagination posteriorly. Lancet with 18–19 serrulae; serrulae triangular with sparse microdenticles, not strongly protruding, and with cypsellae; spine-like setae minute. Male Body 3.7 mm. Colour mostly black, darker than female. Labrum brown; labial and maxillary palps brown; mandibles reddish-brown at apex, brown or dark brown at base; clypeus ventrally slightly brown; hind coxa apically extensively pale; fore and middle trochanters and trochantelli slightly pale; hind trochanters and trochantelli extensively pale; all femora apically slightly pale; all tibiae pale; fore and middle tarsi basally pale; pterostigma and costa dark brown with whitish line at base of pterostigma; sternum 9 pale. Clypeus indistinctly emarginate, more or less truncate; frontal area between antennae rather flat, not distinctly angulate (approaching “ Amauronematus - type ”); postocellar area about 2.5–3.0 times as broad as long; antenna slightly shorter than costa and pterostigma combined; mesepisternum smooth; claws bifid, subapical tooth shorter than apical; projection of tergum 8 distinct, about as long as broad and with truncate apex. Penis valve 1.0 mm, valvispina large and broad at base, about as broad as ventroapical lobe of paravalva, invagination between ventroapical lobe and valvispina indistinct, paravalva with slight invagination ventrally, valviceps apically broader than basally. Host plants Salix sp. Genetics COI Based on 4 specimens, maximum within-species distance is 0% and the nearest neighbours, diverging by a minimum of 8.05%, are Euura erecta and E. viduata. Nuclear Based on 4 specimens, maximum within-species distance is 0% (0.16% based on haplotypes of individual females). The nearest neighbour, diverging by a minimum of 1.64%, is Euura nimbus. Distribution and material examined Palaearctic. Specimens studied are from Finland.