A new species of Pnigalio (Hymenoptera, Eulophidae) parasitizing Eriocrania semipurpurella alpina (Lepidoptera, Eriocraniidae) in China, with its biology and a key to Chinese known species

Abstract A new species of Eulophinae, Pnigalio eriocraniae Li & Yang, sp. n., is described and illustrated. This new species is a larval ectoparasitoid of Eriocrania semipurpurella alpina Xu (Lepidoptera, Eriocraniidae), a leaf miner in birch trees, Betula spp. (Betulaceae), in Qinghai Province, northwest China. The biology of the new species and a key to the known species from China are provided.

Eriocrania semipurpurella alpina Xu has one generation a year in China. Heavy infestations in birch forests were observed in the Qilian Mountains, Qinghai Province, from 2004 to 2014. The life history and biological characteristics of E. s. alpina were observed . Two ichneumonids were reported parasitizing overwintering cocoons of E. s. alpina (Cairangdanzhou et al., 2013;Zhang et al., 2016). A new parasitoid species of Pnigalio was reared from the larvae of the pest and it is described in the present paper. We also provide a key to the known Chinese species of the genus Pnigalio.

Material and methods
The life history and biological characteristics of E. s. alpina were observed at the Beishan Forest Farm (N37°01', E102°21', 2400-2500 m), Huzhu County, Qinghai Province from 2011 to 2016. Adults of E. s. alpina and its parasitoids were collected using intercept traps (IT, Li et al., 2012). As well, birch leaves mined by 3rd to 4th instars larva of the pest were collected from 10 May to 16 June 2011. The leaves were dissected and examined for parasitism. Parasitoid larvae and pupae were kept in glass culture dishes (60 × 10 mm) at room temperature for rearing until parasitoid emergence. The host species was identified by Dr Hou-Hun Li (Nankai University, Tianjin, China).
For the morphological terminology used in this paper, see Bouček (1988) and Gibson (1997). The figures were taken using a Leica M205A microscope with a Leica Microsystem DFC550 digital camera. Photographs were combined using Leica Application Suite ( Diagnosis. Body color usually metallic blue-green to blue-black (only few species black and with or without metallic reflections). Head rounded, subtriangular or subrectangular, wider than high; antenna with 2 annelli, 3-4 funicle segments and 2-3 club segments; mandible subquadrate, usually with a strongly developed acute upper tooth and 4 rounded lower teeth. Pronotum campanulate to subrectangular; scutellum with 2 or 3 pairs of bristles; propodeum with strongly developed median carina, anterior 1/3 with tongue-like projection or without projection, plicae and costulae present or absent, sometimes with additional costulae either complete or incomplete; propodeal spiracle rounded to subovate. Fore wing usually hyaline, veins developed. Metasoma elongate-ovate to narrow and long (Yoshimoto 1983).
Description. Female, holotype (Fig. 1). Length of body of females 3.1-3.4 mm. and of fore wing 2.8-3.0 mm. Body green to blue-green with purple metallic tinge.
Biology. Parasitoid eggs were deposited on the surface of the host's cuticle (Fig. 12). It is a larval ectoparasitoid (Fig. 13) of the third to fourth instar larvae of E. s. alpina Xu (Lepidoptera, Eriocraniidae) which forms leaf mines on birch trees, Betula platyphylla Suk., B. albo-sinensis Burkill and B. utilis D. Don (Betulaceae) in Qinghai Province.
The prepupa (Fig. 14) is motionless, fusiform and with distinct lateral protuberances along the abdominal segments, length of body about 0.6-0.7 mm. The pupa is initially white to white brown (Fig. 15) and then begins to darken to brown or black (Fig. 16), with length 0.4-0.5 mm.
Distribution. Northwestern China (Qinghai Province) Remarks. The new species is similar to Pnigalio maijishanensis Yang & Yao but can be distinguished from the latter by the following combination of characters: scape blue-green with purple metallic tinge; propodeal disc laterally smooth; hind coxa with coarse reticulate sculpture dorsally; hind femur, tibia (apical portion brown), yellow to yellowish white. In addition, the shape of the costulae and the stout bristle are different as indicated in the key.