First description of the male of Solenura ania (Walker) (Hymenoptera: Pteromalidae), a giant pteromalid parasitoid of Trichoferus campestris (Faldermann), with special reference to its sexual dimorphism

Abstract Background The giant pteromalid wasp Solenura ania (Walker) has a distinct sexual dimorphism. The metallic blue female is about 28 mm long and the metallic green male is only about 6 mm in length. This species is an ectoparasitoid of some woodborers, such as Trichoferus campestris (Faldermann), a pest of many live trees and wood furniture and a quarantine pest in many countries. However, the male of this pteromalid was not described prior to this study. New information The male of the species is first described, based on newly-collected material. Photographs of habitus, head, mesosoma, metasoma and other structures of both sexes are provided to facilitate recognition of this giant pteromalid. Sexual dimorphism is also compared in the present study.


Introduction
Pteromalidae is one of largest families in Hymenoptera, including 588 genera and more than 3500 species placed in 31 subfamilies (Noyes 2019). Solenura Westwood, 1868 includes brightly coloured species with large body size, whose female individuals can reach nearly 30 mm in length, 5 times as long as male individuals. Specimens of Solenura, especially males, are relatively rare in museum collections. Therefore, sexual dimorphism in this genus is seldom mentioned, which is representative and extreme in this family or even in Chalcidoidea. In this study, we describe in detail and illustrate with colour microphotographs the male and sexual dimorphism in Solenura ania (Walker).

Materials and methods
This study is based on specimens preserved in the Entomological Museum of Chinese Academy of Forestry. Specimens were examined with an SZH 1500 stereomicroscope (Nikon, Tokyo, Japan). Photographs of the specimens were taken with a CX31 microscope (Olympus, Tokyo, Japan) with the UV-C Optical Totally Focuses System developed by Beijing United Vision Technology Co. Ltd. (Beijing, China). Terminology follows Gibson (2003). Measurements were obtained using a calibrated micrometer.
Head. In dorsal view, head 1.86 times as broad as long; eyes large, width 0.3 times maximum width of head, interantennal triangular region sharp, ocelli large, anterior ocellus with frontal margin touching scrobal depression, ocello-ocular distance 0.5 times post-ocellar distance (Fig. 1a). In frontal view, head 1.2 times as broad as high, eyes 0.65 times head height, frons in narrowest part twice eye breadth; frons and face with strong reticulation; scrobes deep, groove-like, reaching the anterior ocellus and in the form of an inverted V, with scale-like sculpture; outer margin of scrobes parallel with inner margin of eyes; malar sulcus deep, slightly curved; mandibles with two blunt teeth; antennal toruli same level with lower eye margin (Fig. 1b). Malar space 0.55 times eye height, posterior margin of eye touching occiput, thus temple undeveloped (Fig. 1a, Fig. 2a). Antennal radicle 0.13 times scape length; scape slightly curved and broadening in apical half, 3.75 times as long as pedicel, 1 funicular segment 0.5 times 2 funicular segment; clava 1.6 times as long as last funicular segment.

Mesosoma.
Mesosoma with conspicuous and strong punctate reticulation. Pronotal collar quadrate, anterior margin straight, with dense reticulation. Pronotal collar 0.08 times as long as mesoscutum and 0.75 times as long as broad. Mesoscutum 0.65 times as long as broad, mid lobe convex, notauli deep. Axillae large. Scutellum conspicuously convex, 1.3 times as broad as long. Propodeum short, medially 0.25 times length of scutellum, median carina obvious and straight, median area shiny with strong punctuate reticulation; spiracles oval ( Fig. 1a). In lateral view, prepectus delicately reticulate, with long hairs; mesopleuron setose, reticulate to punctatealveolate; metapleuron shiny and densely haired (Fig. 2a). Fore leg with femur slightly curved and 1.6 times as long as tibia, tarsus 1.38 times as long as tibia, tibia with one spur, which is 0.6 times as long as basitarsus, tarsal segments 1-5 with relative length of 40:30:25:30:28; mid leg with femur slightly bulgy, 0.95 times as long as tibia, tarsus as long as tibia, tarsal segments 1-5 with relative length of 15:15:10:8:8; hind leg with femur 4.1 times as long as broad, tibia 1.05 times as long as femur, ventrally with two equally long apical spurs, the spurs 0.5 times as long as basitarsus, tarsus 0.77 times as long as tibia, tarsal segments 1-5 with relative length of 25:25:15:12:15.
Wing. Fore wing nearly reaching the apex of gaster, disc with dense setae; submarginal vein twice as long as marginal vein, marginal vein 1.8 times as long as postmarginal vein and 3.6 times as long as stigmal vein, R vein and Cu vein faint but visible (Fig. 1c). Hind wing about 0.7 times as long as fore wing.

Taxon discussion
History. Walker (1846) described only the female of Epistenia ania, stating that the body colour is "purple" and providing no figures. Matsumura (1912) described the female of Thecasoma longicauda from Taiwan Province, with a habitus figure. Cameron (1909) described the female of Taoga rufipes, stating a body length of only 14 mm. Girault (1927) described only the female of Thaumasurelloides silvae. Boućek et al. (1979) designated lectotypes and synonymised S. telescopica, T. longicauda, T. rufipes with S. ania. Yang (1991) first reported the species in China mainland and redescribed the female. Huang and Xiao (2005) re-described the female, stated the male colour and length and reported one male and one female from Liaoning Province, as well as one female from Beijing City; they illustrated the habitus, head, antenna and First description of the male of Solenura ania (Walker) (Hymenoptera: Pteromalidae), ... metasoma of the female individual. Gibson (2003) reported new distributional records in China, provided a key to the species of the genus and synonymised T. silvae. Sureshan (2005) reported new hosts and new distributional records in India, redescribed the female and illustrated differences between S. ania and S. feretrius. Sureshan et al. (2013) reported new distributional records in India, with 10 males and 20 females parasitising Clytocera chionospila, with field photos of the female and larva.

Notes
The sexual dimorphism of this genus, which is representative and extreme in this family or even in Chalcidoidea, is seldom mentioned prior to this study: (1) the male is green (the female is blue); (2) the male body size is much smaller (the female can exceed 28 mm); (3) the male scape is half as long as head median length (female scape is as long as head median length (Fig. 2d); (4) 4 -7 tergites of male not elongate (4 -7 tergites of female distinctly elongate); (5) pronotal collar of male slightly longer than in female.