First report of Eutrichosomella Girault (Hymenoptera, Aphelinidae) from China, with description of a new species

Abstract The genus Eutrichosomella Girault is recorded for the first time from China (Yunnan Province), and Eutrichosomellayunnanensissp. nov. (♀, ♂) is described and illustrated. A distribution map of this genus is presented.

In the present paper, we describe the twelfth species in the genus, E. yunnanensis sp. nov., from the Yunnan Province of China. This is the first report of the genus Eutrichosomella from China.

Material and methods
Samples were obtained using a pyrethroid fog generated from a thermal fogger (Swingfog SN50, Germany, Model 2610E, Series 3). Specimens were dissected and mounted in Canada Balsam on slides, following the method described by Noyes (1982). Prior to slide mounting, specimens in ethanol were photographed with an Axiocam 305 color digital camera attached to a ZEISS Discovery V12 stereomicroscope. Slide-mounted specimens were photographed with a digital CCD camera attached to an Olympus BX53 compound microscope. Images were processed using Helicon Focus 6 and Adobe Photoshop CS5. Absolute measurements were made using Measurement Systems of the ZEISS Discovery V12 stereomicroscope. All measurements are given in micrometers (μm), except body length, which was measured in millimeters (mm). Scale bars are 100 μm except where otherwise indicated. In the descriptions below, measurements/ ratios in parentheses after measurement/ratio ranges refer to the measurement/ratio of the holotype. The distribution map was generated with the SimpleMappr software (Shorthouse 2010) and ArcMap 10.4.1. All specimens listed below are deposited in Langfang Normal University (LFNU), Langfang, China.
Terminology follows the Hymenoptera Anatomy Consortium (2021) for most body parts except the linea calva, which follows Hayat (1998).
The following abbreviations are used in the text: Description. Female. Body length 1.18-1.63 mm (1.48 mm). Coloration (Figs 1, 2). Head with face and malar space pale, vertex orange yellow and with dark setae, occiput pale. Eyes yellow, ocelli dark brown. Antenna with scape pale yellow and with ventral surface brown, pedicel pale brown to brown, funicle brown, clava with basal half to two thirds brown and remainder parts yellow. Mandible pale with apex dark. Pronotum yellow. Mesosoma mostly orange yellow, with lateral lobe of mesoscutum paler; propodeum with two brown patches interior to each spiracle. Mesopleuron pale. Forewing (Fig. 8) largely infuscated, with hyaline parts as follows: submarginal vein, a curved band adjacent to stigmal vein and apex narrowly. Hindwing (Fig. 9) infuscated medially and apically. Legs generally yellow and suffused with brown on tibiae and tarsomeres. Metasoma with petiole pale yellow, gaster mostly dark brown and with blue reflections, Gt 1 and third valvula brown yellow. Head (Fig. 5), in frontal view, scaly reticulated, with the reticulation becoming elongate laterally. Frontovertex 0.3× head width, vertex with about 30 brown setae. Ocellar tri-angle with apical angle acute. Mandible with two teeth and a truncation. Antenna (Fig. 6) with scape 4.3-4.6× (4.5×) as long as wide; pedicel 3.2-3.6× (3.6×) as long as wide, about as long as funicle segments combined; an anellus ( Fig. 6, inset) is present between pedicel and F1; F1 transverse, with ventral margin a little longer than dorsal margin, 0.7-0.9× (0.9×) as long as wide; F2 quadrate, 1.2× as long as F1; F3 1.5-1.8× (1.8×) as long as wide, 1.3× as long as F1 and F2 combined; clava 3.0-3.7× (3.7×) as long as wide, 0.8× length Mesosoma (Fig. 7). Dorsum of mesoscutum polygonal reticulate, with the sculpture of lateral lobe of mesoscutum elongate on inner side; mesoscutellum mostly re- ticulate, smooth posteriorly, and with a pale longitudinal groove medially; metanotum reticulate on median region; propodeum smooth, but with finely polygonal reticulate sculpture on lateral sides. Pronotum with 4-5 rows of setae, the row along the posterior margin longer. Midlobe of mesoscutum 0.8× as long as wide, with 21-24 (24) setae, the seta on the anterolateral corner and the apical pair of setae long. Lateral lobe of mesoscutum with 3 or 4 setae. Axilla with 1 long seta, its width 1.3× anterior width of mesoscutellum. Mesoscutellum hexagonal, as long as wide, with two pairs of long setae located in anterior part and posterior part, respectively. Distance between anterior pair of scutellar setae 0.4× that between posterior pair. Placoid sensilla located in median region of mesoscutellum; distance between sensilla 0.5× that between posterior scutellar setae. Metanotum 0.7× as long as propodeum in median length. Propodeum with 13-15 (15) short setae (Fig. 7) proximal to spiracle, and with a digital projection on median area posteriorly.

Metasoma
Male. Body length 1.16 mm. Similar to female except as follows. Forewing (Figs  4, 14) with the infuscate patches a little paler than in the female. Legs paler. Gaster (Fig. 3) with Gt 1 and Gt 2 yellow, Gt 3 mostly yellow and with a transverse short brown band on each lateral side, Gt 4 brown posteriorly, Gt 5 -Gt 7 brown.

Distribution. China (Xishuangbanna Dai Autonomous Prefecture of Yunnan Province).
Comments. This species does not run to any couplet in the key to Indian species of Eutrichosomella (Hayat & Veenakumari 2016), and differs from the four Indian species (E. ibra, E. indica, E. keralaensis, and E. veenakumariae) by the following combination of characters: antenna mostly brown with scape and apical of clava pale yellow to yellow (vs. antenna white to yellow, or antenna dark brown with a subapical band on scape and most of clava white; cf. fig. 3 in Manickavasagam and Menakadevi 2012), F3 1.5-1.8× as long as wide (vs. less than 1.4× as long as wide), forewing largely infuscated, with the following parts hyaline: the area below the submarginal vein, a curved band adjacent to the stigmal vein and apex narrowly (vs. forewing with broad or narrow infuscation below margin vein, without hyaline band adjacent to stigmal vein; forewing of E. keralaensis similar to the new species but with a large suboval hyaline spot in the median infuscate area; cf. fig. 6 in Manickavasagam and Menakadevi 2012), postmarginal vein of forewing long, about as long as stigmal vein (vs. absent, or three-fourths of stigmal vein), two pairs of setae on mesoscutellum located in anterior part and posterior part, respectively (vs. both located in posterior part; cf. fig. 4 in Hayat 2014, except E. keralaensis). Apart from the above differences, the new species can be distinguished from E. keralaensis by having scape 4.3-4.6× as long as wide (vs 3.1×), F1 a little wider than long and F2 quadrate (vs. F1 and F2 both 0.5× as long as wide), and propodeum with 13-15 setae proximal to spiracle (vs. at least 3, possibly 4, setae according to redescription of Hayat 2014).
Eutrichosomella yunnanensis sp. nov. seems morphologically close to E. albiclava. Based on Girault's description and images (QMDIU_03328-QMDIU_03335 from the Queensland Museum), E. yunnanensis differs from E. albiclava by following characters: color of gaster apparently darker than mesosoma in slide-mounted specimen (vs. nearly the same according to QMDIU_03330 and QMDIU_03331), pedicel about as long as funicle segments combined (vs. two thirds), F3 1.5-1.8× as long as wide (vs. a little longer than wide), forewing infuscated below marginal vein and subapically (vs. only infuscated below marginal vein, without any distal pigmentation, cf. QMDIU_03332).