Revision of the genus Heterosmylus Krüger, 1913 from China (Neuroptera, Osmylidae)

Abstract A new species of osmylid (Heterosmylus processus sp. n.) is described and the other species in the genus from mainland China are redescribed. Heterosmylus zhamanus Yang, 1987, syn. n. is identified as a junior synonym of Heterosmylus yunnanus Yang, 1986. A key is provided to differentiate Palaearctic and Oriental species of Heterosmylus.


Introduction
Heterosmylus Krüger is a relatively small genus of lance lacewing (Osmylidae: Protosmylinae) described by Krüger (1913a) from the Oriental Region. There are presently nine species in the genus, including seven species in mainland China, one species in Taiwan (Heterosmylus primus Nakahara) and another species (Heterosmylus aspersus Krüger) in northern India. Krüger (1913a) established the genus just based on the comparison with other genera, but the detailed description of the type species H. aspersus was given in a subsequent publication (Krüger 1913b). As for the Chinese species, Nakahara (1955) described Heterosmylus primus from Taiwan. Subsequently, in a series of publications, Yang (1986Yang ( , 1987Yang ( , 1992Yang ( , 1997Yang ( , 1999 described an additional six species from mainland China. However, all the early taxonomists ignored or poorly described the characters of genitalia in osmylids, which result in a vague definition of the genus.
Herein the genus Heterosmylus is revised with a focus on the species from mainland China, and detailed descriptions of genitalic structures are provided for the first time. A revised diagnosis of the genus is proposed based on both external morphology and genitalic characters. The new species, Heterosmylus processus sp. n., is described and Heterosmylus zhamanus Yang, 1987, syn. n. is identified as a junior synonym of Heterosmylus yunnanus Yang, 1986. The distribution of the genus in China is also discussed.

Material and methods
All the described specimens are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing. Terminalia preparations were made by macerating the apex of the abdomen in hot 10% KOH for 3-5 min, neutralized with 10% acetic acid. The apex of the abdomen was then transferred to glycerol for further dissection and examination. After examination it was moved to fresh glycerol and stored in a microvial pinned below the specimen. Images of wings were taken with a Nikon D7000 digital camera. Drawings were made under a light microscope. The terminology for wing venation and genitalia follows .
Type locality. India: Sikkim. Diagnosis. Head brown or dark brown; compound eyes black; antennae shorter than half length of forewing; prothorax black and length longer than width, with yellow setae; meso-and metathorax dark brown with long setae; legs yellow with short brown setae; forewings oblong and subacute at apex, with few brown spots; nygmata clear surrounded by light brown spot; veins thickened; costal cross-veins simple and occasionally bifurcate; forewing Rs with 8-15 branches, distal to the base of wing; cross-veins among Rs branches forming two or three series of gradates; forewing M branching more basally than the divergence of basal branch of Rs; no more than four cross-veins present between the two branches of M; forewing Cu bifurcating near the base of wing; CuA and CuP with numerous pectinate branches; CuP longer than half length of CuA; hind wings similar to forewings in size and shape without any spot apart from pterostigma; hindwing M branching near the base of wing; hindwing CuA with numerous pectinate branches; CuP simple and shorter than half length of CuA; male genitalia with 9 th tergite narrow, and sternite approximately quadrate; ectoproct relatively large, callus cerci rounded and located at the middle or underside of ectoproct; male genitalia composed of gonarcus, entoprocesses and mediuncus, arched gonarcus similar to other genera of Protosmylinae; mediuncus attached with a membrane below gonarcus, mediuncus bent into C-shape laterally; female genitalia with 9 th tergite narrow; spermathecae bent into n-shape with base expanded and apex columniform.
Included species. Heterosmylus aspersus Krüger, H. curvagradatus Yang, H. flavidus Yang, H. limulus Yang, H. primus Nakahara, H. processus sp. n., H. shennonganus Yang, H. wolonganus Yang, H. yunnanus Yang. Comments. Although the type species of Heterosmylus was not described in detail when the genus was established, Krüger provided a detailed description of the type species in a following paper later that year (Krüger 1913a, b). This subsequent work was overlooked by Nakahara (1955), and later Ghosh (2000) presented a brief description for the species without the genitalic characters. Consequently, the systematic status of Heterosmylus was not well defined, although it is clear that the monophyly of Heterosmylus is well supported in the recent phylogenetic work on Osmylidae by Winterton et al. (in press). Heterosmylus also can be distinguished from other genera (Gryposmylus Krüger, Lysmus Navás, Paryphosmylus Krüger) in Protosmylinae based mainly on wing venation. In Heterosmylus, the veins are thickened and branches of forewing M have no more than four ma-mp cross-veins. In both Gryposmylus and Lysmus these are slender and the M vein generally five ma-mp cross-veins. Moreover, the base of costal-field of forewing of Heterosmylus species is narrower compared with that of Gryposmylus. Heterosmylus differs from Paryphosmylus in that the wings are mostly hyaline and single cross-vein presents before the separation of basal branch of Rs (Martins et al. 2016).
Heterosmylus is mainly recorded in the Oriental Region and especially in China ( Fig. 1 Diagnosis. Pronotum with four brown spots at anterior margin, two round brown spots in middle and two brown spots at posterior margin; membrane hyaline, pterostigma yellow, without dark spots besides the pterostigma; veins light yellow at base but brown from middle to the end; mediuncus C-shaped in lateral view with a basal process and boat-shaped in dorsal view. Description. Body length 8.6 mm. Head. Vertex yellow with brown setae; ocelli distinctively brown; compound eyes black; antennae yellow with a brown stripe at base; frons with two brown stripes, genae with two round brown spots; maxillary palpi yellow and thick, labium short and brown. Thorax. Yellow dorsally and dark brown ventrally; pronotum with four brown spots at anterior margin, two round brown spots in middle and two brown spots at posterior margin linking to the mesonotum; mesonotum with two brown spots in middle on both sides; metanotum similar to the mesonotum, with two spots in middle. Legs. Yellow with brown setae; claws brown  with a small tooth. Wings (Fig. 2): Forewing length 15.4 mm, width 6.2 mm; membrane hyaline without any spot besides the yellow pterostigma; veins yellow; costal field broad, cross-veins simple without forks. Cross-veins in radial sector few besides the gradate cross-veins. Rs with 8 branches. The basal cross-vein between R 1 and M edged with a brown mark. Hind wing length 14.4 mm, width 5.3 mm; membrane hyaline, veins light yellow at base but brown from middle to the end. Costal field narrow, pterostigma yellow, and Rs with 7 branches. Abdomen. Yellow dorsally, dark brown ventrally, covered with yellow setae.
Male Terminalia (Figs 3-6). Ectoproct quadrate in lateral view; callus cerci rounded and small. Distal part of gonarcus bent upwards. Entoprocesses curved in middle and dilated apically. Mediuncus (Figs 4-5) C-shaped in lateral view with a basal process and boat-shaped in dorsal view; two mediuncus lobes fused at base and each one raised on both sides, the inner side larger than the outer one.
Distribution. China (Shaanxi). Etymology. The specific name refers to the process at the base of the mediuncus.
Remarks. This species is known from its type locality, Shaanxi province. It is easily distinguished from other species in the genus because of the body coloration, morphology and the genital characters. Heterosmylus processus sp. n. has a smaller body size and hyaline wings, while the others usually have a patterned membrane. Moreover, the mediuncus within the new species possesses a distinct process at the base whereas it is absent in the other species of Heterosmylus. Yang, 1986 Figs 7-13 Heterosmylus zhamanus Yang, 1988: 195. syn Diagnosis. Pronotum black with two yellowish longitudinal stripes at anterior margin; mesonotum with two yellow spots in middle; apex of gonarcus bent upwards and relative long in lateral view.

Female Terminalia
Distribution Diagnosis. Pronotum with two yellow stripes in middle, an oblique brown mark presenting from the pterostigma to the posterior outer margin of forewing; base of mediuncus slender and apex dilated as lobe-shape in lateral view.
Redescription. Body length 8.0 mm. Head. Vertex dark brown, frons brown. Ocelli yellowish, eyes dark grey. Antennae brown, encircled by a yellowish stripe at  base. Clypeus yellow, maxillary palpi and labial palpi dark brown. Thorax. Dark brown. Pronotum with two light yellow stripes medially; mesonotum brown at anterior part with black setae. Wings (Fig. 14). Forewing length 16-17 mm, width 5-6 mm; membrane hyaline, veins brown; pterostigma yellow, but brown on both sides; an oblique brown stripe presenting from the pterostigma to the posterior outer margin; Cu with four brown spots. Outer gradate series of cross-veins and wing margin bordered with fuscous spots. Rs with 13-15 branches. Hind wing length 13-14 mm, width 4-5 mm; membrane hyaline with some light brown spots between Sc and R 1 .
Male Terminalia (Figs 15-18). Ectoproct quadrate in lateral view; gonarcus rodlike in lateral view, distal part upswept and relatively small; mediuncus fused at base and curved into C-shape in lateral view; the base slender and apex dilated as lobe-shape in lateral view.
Distribution. China (Tibet). Diagnosis. Pronotum with two yellow narrow stripes in middle; metanotum with two brown spots on anterior margin; gonarcus sclerotized distally and bent upward and hook-shaped in lateral view; base of mediuncus approximately finger-shaped in lateral view.

Heterosmylus wolonganus
Redescription. Body length 9-11 mm. Head. Vertex yellowish brown; frons yellow with one dark brown spot near antennae; ocelli brown, eyes blackish brown; antennae blackish brown; clypeus yellow, maxillary and labial palpi dark brown  Yang, 1992. Thorax. Pronotum with two yellow narrow stripes in middle with some dark setae on both sides; mesonotum with two yellow longitudinal spots; metanotum with two brown spots on anterior margin. Wings (Fig. 21). Forewing length 18-20 mm, width 6-7 mm; membrane hyaline, veins mostly brown; pterostigma light yellow but brown on both sides; Rs with 10 branches. Four cross-veins present between MA and MP. Hind wing length 16-17 mm, width 5-6 mm; Rs with 11-12 branches, without any distinct spot besides the pterostigma.
Male Terminalia (Figs 22-25). Ectoproct quadrate in lateral view; gonarcus sclerotized distally and bent upwards as hook in lateral view; gonocoxite bent and distally dilated as lobe-shaped in lateral view mediuncus curved into C-shape in lateral view and spoon-shaped in dorsal view; base approximately finger-shaped in lateral view.
Female Terminalia (Figs 26-28). Anterior part of 8 th sternite reduced and short finger-shaped, posterior part broad; ectoproct broad and trapezoid in lateral view; 9 th gonocoxite fusiform in lateral view; 9 th gonostylus long in lateral view; spermatheca bent into C-shape.
Distribution. China (Sichuan, Shaanxi, Gansu, Henan). Redescription. Body length 7-9 mm. Head. Vertex dark brown, frons yellow; ocelli yellowish; Compound eyes brown with some small spots; antennae fuscous except for the yellow scape; clypeus yellow, maxillary and labial palpi black. Thorax. Mostly yellow. Pronotum with a brown longitudinal stripe, and with some long setae on both sides; mesonotum brown on margin; metanotum dark brown with a brown spot medially. Wings (Fig. 29). Forewing length 16-17 mm, width 5-6 mm; membrane light yellow, veins brown and thickened; pterostigma light yellow but brown on both sides; R 1 edged with some brown spots, Rs with 11 branches, cross-veins among branches of Rs forming three series of gradates. Hind wing length 12-14 mm, width 4-6 mm; membrane hyaline with small spots between Sc and R 1 .

Heterosmylus flavidus
Male Terminalia (Figs 30-33). Ectoproct quadrate in lateral view; gonarcus rodlike, but apex not bent upwards in lateral view; gonocoxite bent in the middle; mediuncus C-shaped in lateral view and scoop-shaped in dorsal view.
Female Terminalia (Figs 34-35). 8 th sternite finger-shaped in lateral view; ectoproct broad and approximately elliptical in lateral view; 9 th gonocoxite finger-shaped in lateral view; 9 th gonostylus relatively long and finger-shaped in lateral view; spermathecae bent into C-shape, base thicker than apex.
Distribution. China (Yunnan). Diagnosis. Pronotum with two narrow longitudinal dark brown marks in middle; ectoproct with a dorsal coniform process in lateral view; gonarcus with a short fingerlike process distally in lateral view.

Heterosmyls shennonganus
Redescription. Body length 8-10 mm. Head. Vertex with a brown cross-stripe; frons yellow but brown on both sides; ocelli large and prominent, compound eyes shiny black; antennae dark brown; clypeus fulvous, maxillary and labial palpi brown.
Thorax. Pronotum with two narrow longitudinal dark brown marks in the middle; mesonotum with dark setae; metanotum without spots. Wings (Fig. 36). Forewing length 16-17 mm, width 6.4 mm; membrane hyaline, veins mainly brown; pterostigma yellowish but brown on both sides; costal field with three or four brown spots; r1-rs edged with brown marks; Rs with 8-9 branches, cross-veins among branches of Rs forming two series of gradates; the outer gradate cross-veins edged with brown spots. Hind wing length 15.5 mm, width 5.4 mm. Membrane hyaline with few spots.
Male Terminalia (Figs 37-40). Ectoproct approximately quadrate with a dorsal coniform process in lateral view; gonarcus approximately rod-like and distally sclerotized with a short finger-like process in lateral view; gonocoxite curved as ancon and distally  Yang, 1997. dilated as lobe; mediuncus curved and thickened in lateral view and boat-shaped with a cone-shaped apex in dorsal view.
Distribution. China (Henan, Shaanxi, Hubei, Chongqing). Diagnosis. Two yellow longitudinal stripes present from pronotum to mesonotum. mesoscutellum bright yellow, metanotum with a central yellow stripe; apex of gonarcus slightly dilated, short and curved dorsally.  Yang, 1999. Redescription. Body length 7-10 mm. Head. Vertex shiny yellow with a brown round spot in middle and a greyish yellow transverse band near antennae; frons bright yellow with a black brown stripe; ocelli grey but black at base; compound eyes grey and glossy; antennae black; clypeus yellow, maxillary and labial palpi dark brown. Thorax. Dark brown with two yellow longitudinal stripes from pronotum to mesonotum. mesoscutellum bright yellow, metanotum with a central yellow stripe. Wings (Fig. 44). Forewing length 15-17 mm, width 5-6 mm; membrane hyaline, veins fuscous with numerous long setae; pterostigma yellow but brown on both sides. Crossveins r1-rs edged with dark brown spots. Rs with 8-9 branches, gradates cross-veins with brown marks. Hind wing length 13-14 mm, width 4-6 mm; membrane hyaline without spots besides the pterostigma.
Male Terminalia (Figs 45-48). Ectoproct approximately pentagonal in lateral view; gonarcus rod-like in lateral view, apex slightly inflated, short and curved dorsad; mediuncus fused at base and scoop-shaped in dorsal view and apex flat-bottomed in dorsal view.