Osmylus Latreille, 1802
(Figs 4, 18–21)
(= Hyposmylus McLachlan, 1870: 200 . Type species: Osmylus punctipennis Walker, 1860: 183)
(= Dictyosmylus Navás, 1910: 189 . Type species: Dictyosmylus lunatus Navás, 1910: 189)
(= Plesiosmylus Makarkin, 1985: 41 . Type species: Osmylus tessellatus McLachlan, 1875: 36)
(= Plethosmylus Krüger, 1913a: 43 . Type species: Osmylus hyalinatus McLachlan, 1875: 181)
Type species. Hemerobius maculatus Fabricius, 1787: 247 (by monotypy).
Diagnosis. Wings elongate, broad, posterior margin occasionally straight distally; FW typically with irregular mottled infuscation; HW mostly hyaline except for pterostigma wing margin and wing base; FW subcostal veinlets often forked near wing margin distally, interlinking crossveins present or absent; RP with at least two gradate series in both wings, dense crossveins in basal 3/4 of wing, RP1 originating close to origin of RP; FW M fork close to, or opposite to RP1; FW cubital area with crossveins present or absent; female forecoxa typically with a prominent process on the anterior surface; male tergite 9 with variably-shaped dorsal processes often present; gonarcus mainly external, enlarged, sclerotized and densely setose in lateral view; entoprocessus shape variable and poorly sclerotised. Female genitalia with sternite 8 variable in shape, sometimes with lateral processes; spermatheca oval or cylindrical.
Comments. Some authors further divide Osmylus into two subgenera ( Osmylus and Plesiosmylus), although the basis for at least Plesiosmylus is problematic due to a lack of apomorphic characters (Makarkin 1985). Matsuno & Yoshitomi (2016) described the larvae of three Japanese species and found that larval characters also did not support the division of subgenera as proposed by Makarkin (1985). They also synonymised O. kisoensis Iwata with O. pryeri McLachlan. Krüger (1915) erected Plethosmylus largely based on the interlinking of costal veinlets with crossveins, but this has not been accepted by some subsequent authors (e.g., Nakahara, 1914; Makarkin, 1985; Sekimoto & Yoshizawa, 2011). Xu et al. (2016) provided a key to species of Osmylus, but it requires examination of both male and female genitalic characters for an identification. The lack of external diagnosable features and limited specimens on which species have been described means that we do not fully understand the intraspecific variability expressed in the genus and how it impacts the validity of all species described. Osmylus appears to mostly be distributed in the temperate Palaearctic region.
Included species.
O. angustimarginatus Xu, et al., 2016 (China)
O. atomatus (Yang et al. in Huang et al., 1988) (China)
O. biangulus Wang & Liu, 2010 (China)
O. bipapillatus Wang & Liu, 2010 (China)
O. cilicicus Krüger, 1913c (Turkey)
O. conanus Yang, 1987 (China)
O. decoratus Nakahara, 1914 (Japan, Russia)
O. elegantissimus Kozhanchikov, 1951 (Azerbaijan, Georgia, Turkey, Ukraine, Russia)
O. fuberosus Yang, 1997 (China)
O. fulvicephalus (Scopoli, 1763) (Europe)
O. hyalinatus McLachlan, 1875 (Japan, Russia)
O. lucalatus Wang & Liu, 2010 (China)
O. maoershanicola Xu, et al., 2016 (China)
O. megistus Yang, 1987 (China)
O. minisculus Yang, 1987 (China)
O. multiguttatus McLachlan, 1870 (Turkey, Ukraine)
O. pachycaudatus Wang & Liu, 2010 (China)
O. posticatus Banks, 1947 (China)
O. pryeri McLachlan, 1875 (Japan, Russia) (= O. kisoensis Iwata, 1928; = O. shikokuensis Kuwayama, 1953) O. punctipennis Walker, 1860 (China, India)
O. shaanxiensis Xu, et al., 2016 (China)
O. taiwanensis New, 1991 (China)
O. tessellatus McLachlan, 1875 (Japan, Russia)
O. wuyishanus Yang, 1999 (China)
O. xizangensis Yang et al. in Huang et al., 1988 (China)
O. zheanus (Yang & Liu, 2001) (China)