Three new species of Stenomesius Westwood (Hymenoptera, Eulophidae) from China, with a key to Chinese species

Abstract Three new species of Stenomesius Westwood, S.guanshanensissp. nov., S.hanisp. nov., and S.harbinensissp. nov., are described from China. A key to all species of the genus Stenomesius in China is provided.


Introduction
The genus Stenomesius (Hymenoptera, Eulophidae) was erected by Westwood (1833) based on European species S. pulchellus Westwood and S. maculatus Westwood. Stenomesius pulchellus was subsequently designated as the type species by Westwood (1840), but S. pulchellus and S. maculatus were both synonymized with S. rufescens (Retzius). Noyes (2021) listed 21 species in this genus, but S. aspidicola Ashmead is a misspelling of S. aphidicola Ashmead and S. pantnagarensis Agnihotri and Khan was synonymized with S. orientalis Agnihotri and Khan (Agnihotri and Khan 2004;Khan et al. 2005), so currently the genus contains 19 valid species. Only two species were known from China: S. japonicus (Ashmead) and S. maculatus Liao (Bouček 1977;Liao et al. 1987;Huang 2001, 2002). Most species of the genus are parasitoids of Lepidoptera, and recorded host families include Gelechiidae, Lyonettiidae, Glyphipterygidae, Tortricidae, Pyralidae, and Noctuidae (Bouček 1988). One specimen from Sulawesi (Indonesia 1949) is labelled as having been reared from eggs of Scirphophaga innotata (Walker), the white rice borer, but this record needs confirmation (Bouček 1988).
This study describes three new species of the genus Stenomesius and provides a key to all species of the genus distributed in China.

Material and methods
All specimens were collected by sweeping or yellow pan trapping, and they were dissected and mounted in Canada balsam on slides following the method of Noyes (1982), or mounted on a card. Photos were taken with a digital CCD camera attached to an Olympus BX51 compound microscope or Aosvi AO-HK830-5870T digital microscope. Measurements were made using an eyepiece reticle, or using the ruler tool in Adobe Photoshop 2020.
Terminology follows the Hymenoptera Anatomy Consortium (2021), and the following abbreviations are used: F1-4 = flagellomeres 1-4; MV = marginal vein; OOL = minimum distance between lateral ocellus and eye margin; PMV = postmarginal vein; POL = minimum distance between lateral ocelli; SMV = submarginal vein; STV = stigmal vein; T1-7 = gastral tergites 1-7. All type material is deposited in the insect collections at Northeast Forestry University (NEFU), Harbin, China. Diagnosis. Lower face yellow; interantennal area yellowish; upper face and vertex black with area around eye margins yellow; antenna inserted at high above the lower eye margins and on the middle of between anterior ocellus and lower margin of clypeus. Pronotum with dorsal side black and lateral sides yellowish; mesoscutum, axillae and scutellum yellow or yellowish except about posterior 1/6 of scutellum black; midlobe of mesoscutum with 4 pairs of long setae; scutellum light alutaceous; dorsellum and lateral panels black; propodeum yellowish with carina brown.
Mesosoma (Fig. 1). Pronotum with a row of setae on anterior margin and 2 long pale yellow setae on posterior median margin; mesoscutum with anterior half reticulate and posterior half almost smooth; midlobe of mesoscutum with 3 pairs of long setae on median area and 1 pair of long setae on posterior area; axillae and scutellum shiny, light alutaceous; axillae well separated from each other; scutellum with 2 pairs of long setae; sublateral grooves not meeting each other medially on posterior margin; propodeum smooth, with plicae and H-shaped carina; each propodeal callus with 6 long setae; forewing (Fig. 5) 2.7 × as long as wide; speculum absent; hind wing ( Fig. 6) about 6.2 × as long as wide; metatibial spurs shorter than corresponding basitarsomere. Relative measurements (length): SMV = 22; MV = 27; PMV = 11; STV = 8. Metasoma (Fig. 1) Diagnosis. Lower face yellow; upper face dark brown except lower most about 1/6 yellow; vertex dark brown with 2 triangular, yellow spots; antenna inserted at middle of the face; scape yellow, with about apical half of dorsal surface brown; mesoscutum with anterior half black and posterior half yellow; midlobe of mesoscutum with 3 pairs of long setae; scutellar-axillar complex dark brown, metanotum black; propodeum yellowish brown.
Description. Female. Length 1.7-1.9 mm. Lower face yellow; upper face dark brown except lower 1/6 yellow; vertex dark brown with a triangular, yellow spots at each side; scape yellow with about apical half of dorsal surface brown, pedicel and flagellum black; mandibles yellow, with teeth brown; gena yellow; occiput mostly dark brown. Pronotum yellow, with a dark brown spot in the middle; mesoscutum with anterior half black and posterior half yellow; axillae and scutellum dark brown; dorsellum and lateral panels black; propodeum brownish; Petiole dark brown; gaster mainly yellowish-brown, with anterior half of lateral margins dark brown, T3-5 each with a transverse dark brown stripe; ovipositor black. wings hyaline with veins pale brownish yellow; legs yellow, with claws brown.

Distribution. China (Heilongjiang).
Etymology. The species is named for Prof. Hui-Lin Han of the Northeast Forestry University, Harbin, China.
Remarks. Stenomesius hani is similar to S. anati Khan & Singh in sharing: antenna inserted in middle of face; face with dark brown infuscation above antennal torulus; anterior half of mesoscutum, scutellum, and axillae with dark brown infuscation. Stenomesius hani can be separated from the latter by the following combination of characters: scutellum with 2 pairs of setae (3 pairs in S. anati); distal 1/3 costal cell with setae (whole costal cell with setae in S. anati); gaster 1.1× as long as mesosoma (shorter than mesosoma in S. anati). Diagnosis. Vertex black; occiput mostly black with two small, yellow spots near eyes margins; lower face yellow; upper face black; antenna inserted in above the lower eye margins; scape mostly yellow with about apical half of dorsal surface pale brown; pronotum with dorsal surface black and lateral sides yellowish; mesoscutum dark brown; midlobe of mesoscutum with 3 pairs of long setae; scutellar-axillar complex, metanotum, and propodeum black.
Male. Unknown. Host. Unknown. Distribution. China (Heilongjiang). Etymology. The specific name is derived from the name of the type locality.