A new species of Myiocephalus Marshall (Hymenoptera, Braconidae, Euphorinae) from China

Abstract A new species of the genus Myiocephalus Marshall, 1898, M. cracentis Li, sp. nov. from the Palaearctic (China, Ningxia, Hubei), is described and illustrated. A key to known species of Myiocephalus is provided. Myiocephalus boops (Wesmael, 1835), is a new record for Jilin province (NE China).


Introduction
Euphorinae (Hymenoptera, Braconidae) is a large subfamily of endoparasitoid wasps with more than 1,270 described species worldwide (Yu et al. 2016). Their morphology varies greatly and this is quite unusual for a single subfamily. This highly polymorphic subfamily is characterized by only one derived character state: the postero-distally open first subdiscal cell of the fore wing because fore wing CU1b is absent (Shaw 1985;Tobias 1986). The other general morphological character of Euphorinae is the often, but not always, bent fore wing vein SR1+3-SR, and a more or less specialized scape, eyes, clypeus, mandible, fore leg, first metasomal tergite, and ovipositor. Stigenberg et al. (2015) divided this subfamily into 14 tribes and 52 genera. Chen and van Achterberg (2019) recognized two additional tribes, Eadyini and Proclithrophorini, of which the latter had been included in the Townesilitini by Stigenberg et al. (2015) on the basis of their concatenated molecular data (18S, 28S, CAD, and COI). However, the morphology of Proclithrophorini conflict this synonymy and its position remains unresolved. Myiocephalus is the only genus of the Myiocephalini Chen & van Achterberg, 1997, which is associated with ant nests of the genus Formica but has never been reared (Donisthorpe 1927).
The genus Myiocephalus Mashall (recognized as Loxocephalus Forster) was first placed in its own tribe as Loxocephalini by Shaw (1985). Myiocephalus is the sister group of the lineage comprising Comsmophorus + Syntretini supported by morphological characters: mesonotum shiny and notauli absent; scutellar furrow without cross-carinae; and dorsope absent (Shaw 1985). Stigenberg et al. (2015) supported the Syntretini as the sister tribe to the Myiocephalini on the basis of their concatenated molecular data (18S, 28S, CAD, and COI) and unique morphological characters (the bulging eyes and smooth mesosoma). There are only two other known tribes of euphorine wasps (Syntretini and Neoneurini) attacking Hymenoptera except Myiocephalini. Myiocephalini is more closely related to Syntretini, based on both morphological and molecular evidences.
The genus Myiocephalus Marshall is, although they are rare in collections, one of the most distinctive euphorine genera with its strongly transverse (and females anteriorly more or less concave) head, and elongate first metasomal tergite with very large laterope and compressed metasoma. Four species of the genus Myiocephalus are currently known: M. boops (Wesmael, 1835); M. niger Fischer, 1957;M. laticeps (Provancher, 1886); and M. zwakhalsi van Achterberg, 2019 (Tan et al. 2019).
The first author examined the collections applying the key of Tan et al. (2019) and discovered a new species than it was confirmed by second author and is described below.

Materials and methods
Studied material was selected from the entomological collections of the Beneficial Insects Institute, China (BIIC). The specimens were collected using a sweep net. All specimens studied are deposited in BIIC.
Specimens were examined using a Zeiss Stemi 2000 stereomicroscope. The photographs were taken with a computer-connected Leica DFC450 digital camera mounted on a Leica M205C stereo microscope. All images were further processed using minor adjustment in Adobe Photoshop CC, such as image cropping and rotation, adjustment of contrast and brightness levels, color saturation, and background enhancement.
The terminology used for measurements and descriptions of morphological characters follows van Achterberg (1988van Achterberg ( , 1993. The veins of the fore wing are illustrated on Figure 20. Diagnosis. Laterope large, deep and submedially situated in slender first tergite; head in dorsal view strongly transverse and usually slightly concave anteriorly; eyes enlarged and protruding; clypeus rather narrow; scapus slightly or not enlarged and subequal to or shorter than third antennal segment; maxillary palpi with five segments, labial palpi with three segments; vein 1-SR+M of fore wing absent; vein 1-R1 longer than pterostigma; vein M+CU1 largely unsclerotized; middle and hind legs elongated; metasoma of ♀ strongly compressed with fifth sternite of ♀ finger-like protruding posteriorly; hypopygium of ♀ with long setae apically or hypopygium medially membranous. (Tan et al. 2019 The scapus of ♂ 1.0 × as long as wide (Fig. 17); minimum width of face 2.0 × as long as height (Fig.17); length of the malar space of ♂ 1.1 × basal width of the mandible (Fig. 17) The scapus of ♂ 1.3 × as long as wide (Fig. 18); minimum width of face 1.6 × as long as height (Fig. 18); length of the malar space of ♂ 1.2 × basal width of the mandible (Fig. 18) Area near occipital carina dark brown and occiput dorsally brown (Fig. 19); vein cu-a of fore wing of ♀ as long as 1-CU1 and oblique (Fig. 20); prepectal carina absent medio-ventrally (Fig. 21) (Fig. 3); vein cu-a of fore wing of ♀ distinctly longer than 1-CU1 and vertical (Fig. 7); prepectal carina present medio-ventrally (Fig. 8); antenna of ♀ with 32 segments (Fig. 6) Description. Holotype, ♀, length of fore wing 3.4 mm, and of body 3.7 mm. Head. Antenna with 32 segments and 1.2 × as long as fore wing, third segment 1.1 × as long as fourth segment, third, fourth and penultimate segments 4.6, 3.9 and 2.8 × as long as wide, respectively (Fig. 6); eye 3.4 × as long as temple in dorsal view; temples directly and linearly narrowed behind eyes (Fig. 3); OOL:OD:POL = 8:4:13; vertex and frons largely superficially coriaceous and shiny; in front of anterior ocellus with small convexity (Fig. 3); occipital carina complete and dorsally remaining shortly below upper level of eyes (Fig. 5); minimum width of face 1.9 × as long as height; face mainly very finely densely punctulate, but latero-ventrally largely smooth, with whitish setae and satin sheen (Fig. 4); clypeus convex medially and with slightly concave and thin ventral lamella (Fig.  4), medially finely rugulose; anterior tentorial pits large (Fig. 4); malar suture deep, narrow and straight; length of malar space equal to basal width of mandible and malar space in anterior view straight (Fig. 4); mandible slender, strongly twisted, outer side convex and with deep basal depression (Fig. 4), its second tooth similar to first tooth and acute.
Legs. Middle and hind legs very slender tibia and tarsus together ca. 2.4 × longer than femur, tibia ca. 3.7 × longer than coxa; fore leg normal, tibia nearly 3 × as long as coxa; length of femur, tibia and basitarsus of hind leg 7.6, 22.7 and 6.0 × as long as their maximum width; hind tibial spurs 0.2 × as long as basitarsus.
Male. Length of fore wing 3.0 mm, and of body 2.9 mm; antenna with 30 segments; length of malar space 1.8 × basal width of mandible; first tergite smooth and shiny; only sternites of basal half of metasoma folded medially and tergite three to eight weakly concave posteriorly (Fig. 13).
Biology. Unknown. Distribution. China (East Palaearctic). Etymology. Named after the slender pterostigma and marginal cell of the fore wing, long narrow legs, and antennae: "cracentis" is Latin for "slender, graceful".