Three new species of Osmylus Latreille from China (Neuroptera, Osmylidae)

Abstract Three new species of Osmylus Latreille are described from China: Osmylus maoershanicola sp. n., Osmylus shaanxiensis sp. n. and Osmylus angustimarginatus sp. n. These new species are distinguishable from other related species by the shape of the 9th tergite of both sexes, as well as the shape of gonarcus, mediuncus and spermatheca. A key is given to differentiate Palaearctic and Oriental species of Osmylus.

The biology of osmylids is still poorly known. Osmylus is known to be univoltine and adults feed as generalists on fungal spores, pollen, algae, mites and insects; they sit temporarily on foliage of plants along streams or river banks in daytime (Devetak 2007, Gepp 1976, Withycombe 1923. The biology of larvae remains controversial. Latreille (1805) and Stein (1838) deduced that the larvae of Osmylus are aquatic. However, Stitz (1936) and Eisner (1989) reported correctly that the larvae simply live in the water margin (the riparian interface) but cannot survive submersion. Accordingly, the larvae should definitely be regarded as terrestrial.

Materials and methods
The specimens in this study were examined under an Optec SZ760 stereomicroscope with direct light. The terminal of abdomens were removed and soaked in the 10% NaOH for boiling water bath and stored in a glycerin-filled micro-vial mounted on the pin beneath specimen. The terminology for wing venation and genitalia follows New (1983), Adams (1969) and New (1983). All type specimens are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing.

Diagnosis.
Moderate to large body size (body length 15-20 mm); forewing generally large and broad (length 20-30 mm), with numerous fragmentary marks; two nygmata present at the center and the proximal base of wing between MP and Rs; veins dark brown; costal cross-veins generally bifurcate distally, without interlinking veinlets; crossveins among branches of Rs forming at least two series of gradates; MP forked close to the base, MP 2 with many branches. The hindwing resembles the forewing in shape, but with fewer spots. The 9 th tergite has variably-shaped dorsal process. Genitalia are composed of a gonarcus and a mediuncus; the gonarcus is variable in shape, consisting of a sclerotized and pilose external section posteriorly with a lightly sclerotized anteriorlateral section, the latter laterally with an anterior rod shaped process (i.e., baculum of some authors) which is sometimes articulated. The mediuncus (i.e., parameres of some authors) is curved with a fused base (although the shape is variable in O. pachycaudatus).
The mediuncus is subtended laterally by the rod-shaped, paired parameres (i.e., subarcus of other authors) that are not fused anteriorly. The female 9 th tergite occasionally has a ventral process, the gonapophysis lateralis is generally finger-like and articulated with stylus distally, and the spermatheca is either oval or cylindrical in shape. Comments. Osmylus has been often confused with three other genera, Grandosmylus Makarkin, 1985, Parosmylus Needham, 1909and Plethosmylus Krüger, 1913. Banks (1913 advanced that Parosmylus should be a junior synonym of Osmylus because the spur on the coxa in Parosmylus is also present in some species of Osmylus. Krüger (1913) erected the genus Plethosmylus based on venation characters (presence of interlink veinlets between costal cross-veins). Nakahara (1914) considered the opinion of Krüger subjective and synonymized the latter genus. Kuwayama (1953Kuwayama ( , 1962 again separated Plethosmylus, differentiating it from Osmylus by the presence of interlinking veinlets among the costal and two basal Rs-Mp cross-veins before the proximal nygma. However, Makarkin (1985) revised the status of Plethosmylus, synonymizing it with Osmylus and establishing a new subgenus Plesiosmylus within Osmylus. He also established a new genus Grandosmylus, separated from Osmylus by the irregular gradate cross-veins and the shape of 9 th sternite in males and 8 th sternite in females; this opinion was accepted by Sekimoto (2011) in his revision of Japanese Osmylus. The relationship among Grandosmylus, Parosmylus and Plethosmylus remains unclear. Wang and Liu (2009) clarified the generic status of Parosmylus, after reviewing specimens from mainland China, and they concluded that both genera could be valid due to differences in the number of gradate series, the configuration of gonarcus and the shape of spermatheca (Wang and Liu 2009). Furthermore, after re-examining the specimens of Plethosmylus from mainland China, we observed that Osmylus and Plethosmylus possessed significant differences in male genitalia (the configuration of gonarcus) and in female genitalia. Moreover, the interlink veinlets among costal cross-veins could conveniently divide them. Considering the vague relationships among these genera, we consider is suitable to maintain them as separate genera until a robust phylogenetic work can be conducted in the future. In this paper, three new species of Osmylus are described from China: O. maoershanicola sp. n. O. shaanxiensis sp. n. and O. angustimarginatus sp. n., primarily based on genital characters. The structure of spermatheca complicated (Fig. 2a)  The length of process of 9 th tergite in male significantly longer than width ( Fig. 3c-d)  Gonarcus with only one lateral posteroventral protuberance in lateral view (Fig. 5b) (Fig. 5d) ...O. angustimarginatus sp. n. 13 The process of 9 th tergite in male cylindrical (Fig. 3c) Description. Head. Vertex yellowish-brown with brown setae; eye dark gray, ocelli yellow, area within ocelli black. Antennal flagellum missing, scape and pedicel dark brown; frons yellow. Thorax. Pronotum dark brown, posterior margin slightly wider,  with black brown setae; meso-and metanotum black with brown setae. Legs yellow with brown setae; pretarsal claws dark brown.
Male terminalia (Fig. 5a-e). Scent glands slender. 9 th tergite long and narrow with a short, dorsal finger-like process (Fig. 5a), ventral margin slightly tapered. 9 th sternite trapezoidal in lateral view. Ectoproct triangular in lateral view, callus cerci round. Distal part of gonarcus well sclerotized and approximately triangular, ventral part membranous with a triangular protuberance in lateral view (Fig. 5b); anterior arm of gonarcus slender; mediuncus dilated basally with a sharp backward end, slender apically and coated by a membrane in lateral view; rod-shaped paramere beneath the mediuncus slightly bent in lateral view, posterior end sharp.
Distribution. Presently known only from Guangxi Province, China. Etymology. The specific name 'maoershanicola' refers to 'Maoershan Mountain', the type locality.
Remarks. The dorsal finger-like process of 9 th tergite of Osmylus maoershanicola sp. n. is similar to O. pryeri and O. biangulus, but this new species can be identified by the distinctive shape of the gonarcus. There are two prominent ventral protuberances in the distal part of gonarcus of O. pryeri and O. biangulus (Fig. 3b) but only one in O. maoershanicola sp. n. (Fig. 5b). Furthermore, the distal gonarcus is cone-shaped in O. biangulus but triangular in O. maoershanicola and the spermatheca is short and bent rod-like in O. biangulus (Fig. 2e) but approximately spherical in O. maoershanicola (Fig. 5g). Diagnosis. Wing broad, with numerous dark brown spots on the margin. Male: 9 th tergite with a median narrowing, with a small tuberous dorsal process in lateral view; protuberance of posteroventral gonarcus papillary. Base of mediuncus knifeshaped in lateral view. Female: gonapophysis lateralis basally fused with a triangular sclerite, spermatheca bent, cylindrical.

Osmylus shaanxiensis
Description. Head. Vertex dark brown. Ocelli yellow, area comprised among ocelli dark brown, eye dark brown; frons brown. Thorax. Pronotum dark brown with yellow long setae; meso-and metanotum dark brown. Legs yellow with dark yellow setae, pretarsal claws dark brown.
Remarks. The new species can be distinguished from other species by the small hemispheric dorsal process of the 9 th tergite in male (Fig. 7a). Although O. shaanxiensis sp. n. is similar to O. conanus, they can be easily separated by the differences of gonarcus and gonapophysis lateralis. The distal part of gonarcus in O. conanus protrudes slightly but the same part in O. shaanxiensis sp. n. protrudes significantly in lateral view (Fig. 7b). Also compared with O. conanus, the spermatheca in O. shaanxiensis sp. n. is longer and more bent (Fig. 7f).   Diagnosis. Male: 9 th with a finger-like dorsal process. Gonarcus distally triangular in lateral view, ventral margin well sclerotized; base of mediuncus slightly protuberant distally in lateral view. Female: gonapophysis lateralis finger-like; spermatheca approximately spherical.
Description. Head. Vertex yellow brown, with dark brown setae; ocelli light yellow, area comprised among ocelli dark brown; eyes gray with metallic reflection; frons black. Thorax. Pronotum dark brown, with yellow setae; meso-and metanotum fuscous, with black stripes. Legs yellow, with short setae, pretarsal claws dark brown.
Male Terminalia (Fig. 9a-e). Scent glands stout. 9 th tergite wide, with a fingerlike process; 9 th sternite approximately rectangular in lateral view; ectoproct small, callus cerci round; gonarcus distally well sclerotized and triangular in lateral view, ventral margin well sclerotized; anterior arm of gonarcus slender and basally dilated; mediuncus slightly finger-like at base, more slender apically in lateral view; rod-shaped paramere beneath the mediuncus slightly bent in lateral view.
Distribution. Known only from Chongqing, China. Etymology. The specific name 'angustimarginatus' the compound of Latin deribation, from angusti-(narrow) and marginatus-(margin), refers to the well sclerotized ventral margin of the gonarcus in lateral view.
Remarks. The dorsal process of 9 th tergite in the male of O. angustimarginatus sp. n. is finger-like (Fig. 9a), closely resembling the condition observed in O. maoershanicola sp. n. However, the ventral margin of the gonarcus of O. angustimarginatus sp. n. is well sclerotized (Fig. 9b), clearly differentiating it from O. maoershanicola sp. n. Moreover, female gonapophysis lateralis of O. angustimarginatus sp. n. is more slender in comparison with the fusiform gonapophysis lateralis of O. maoershanicola sp. n. (Fig. 5f).