Pleroneura itoi Shinohara

Shinohara, Akihiko, 2016, The sawfly genus Pleroneura (Hymenoptera, Xyelidae) of Japan: P. itoi n. sp. and a key to species, Zootaxa 4121 (4), pp. 495-500 : 496-497

Pleroneura itoi Shinohara , n. sp.

( Figs 1 C, D, 2C, D, H)

Description. Female (holotype). Length (excluding sawsheath) about 4.3 mm. Head black, with pale brown marks as in Figs 1 C, D, 2C, D; antenna pale brown, with 1st flagellomere blackish brown; palps pale brown, inner margin of mandible blackish brown. Thorax black, with two obscure dark reddish brown spots on mesoscutellar lateral lobe, one near borders of median lobe and another on lateral surface, and median posterior part of ventral surface of mesothorax pale greenish brown; tegula pale brown (medially blackish brown). Legs pale brown, with all coxae and trochanters, base of fore femur, and most of mid and hind femora (except for apices) black. Wings subhyaline; veins and stigma translucent blackish brown, the latter becoming paler posteriorly. Abdomen black, with lateral part of each tergum somewhat brownish, and caudal part, including narrow posterior margin and lateral part of 8th tergum, lateral ventral part of 9th tergum and valvifer 2 entirely pale brown; valvula 3 blackish brown, pale brown basally and apically.

Mesoscutal lateral lobe weakly microsculptured between punctures, feebly shining. Tarsal claws in all legs with one small subapical tooth. Forewing with short crossvein lr-m; veins Rsl and Rs2 branching before origin of crossvein 2r-m, and distance between separation of Rsl and Rs2 and origin of 2r-m about 1/3 length of distance between origin of 2r-rs and that of 2r-m ( Fig. 1 C). Valvula 3 ( Fig. 2 H) slender, in lateral view, slightly upturned, about 0.60× length of hind tibia, 0.54× head width, and 0.87× length of 1st flagellomere.

Male. Unknown.

Material examined. Holotype: ♀, Mt. Wasamatayama, 1,100 m alt., Kamikitayama-mura, Nara, 27. IV. 2013, F. Ito.

Distribution. Japan (Honshu).

Host plant. Unknown.

Etymology. This new species is named after Mr. F. Ito, Kanmaki, who collected the holotype.

Remarks. Pleroneura itoi is a small, light-colored species, with a short and slender valvula 3. It will be easily distinguished from the other Japanese species by the key below. From the western Palearctic and Nearctic congeners ( Smith et al. 1977; Blank 2002), P. i t oi is separated by the combination of the short and slender valvula 3 ( Fig. 2 H, about 0.6 × length of the hind tibia), presence of the subapical tooth on the tarsal claws and the largely pale-marked head ( Figs 1 C, D, 2C, D).

No information is available as to the host plant of this species, but Abies homolepis Sieb. & Zucc. is a good candidate, because it is probably the only species of fir distributed in the type locality ( Liu 1971).

Figures

FIGURE 1. Pleroneura spp., ♀. A, B, P. hi k o s an a, Mt. Kiyosumiyama, Chiba; C, D, P. itoi, holotype; E, F, P. piceae, Asahidake-onsen, Hokkaido; G, H, P. subulata, paratype, Meotobuchi-onsen, Tochigi.

FIGURE 2. Pleroneura spp., ♀, heads (A – F) and ovipositor sheaths (G – J). A, G, P. hi k o s an a, Mt. Kiyosumiyama, Chiba; B, same species, Mt. Tokusagamine, Yamaguchi; C, D, H, P. itoi, holotype; E, I, P. piceae, Asahidake-onsen, Hokkaido; F, J, P. subulata, paratype, Meotobuchi-onsen, Tochigi.