﻿A review of the Strongylophthalmyiacoarctata subgroup (Diptera, Brachycera, Strongylophthalmyiidae) from China, with the descriptions of three new species

﻿Abstract The species belonging to the Strongylophthalmyiacoarctata subgroup of the S.punctata group (Diptera: Brachycera: Strongylophthalmyiidae) from China are reviewed. Six species are recognized, including three new species: S.corniculatasp. nov., S.flagellicornissp. nov., and S.tangwanganasp. nov.Strongylophthalmyianarwhal Evenhuis, 2020 and S.raricornis Shatalkin, 1981 are recorded from China for the first time, and S.raricornis is also recorded from South Korea for the first time. An identification key to the Asian species of the S.coarctata subgroup is provided.


Introduction
The acalyptrate family Strongylophthalmyiidae currently contains 90 species divided into two genera: the monotypic Nartshukia Shatalkin, 1993 from Vietnam, and the speciose Strongylophthalmyia Heller, 1902 from the Australasian, Nearctic, Oriental, and Palearctic realms (Evenhuis 2016(Evenhuis , 2020Galinskaya and Shatalkin 2018). Members of Strongylophthalmyia are mostly assigned into four species-groups (S. crinita group, S. fascipennis group, S. punctata group, and S. ustulata group), with nearly 40% of species belonging to the S. punctata group, while the other 12 species are unplaced and two are treated as nomen dubia (Shatalkin 1996;Evenhuis 2016). The S. punctata group is characterized by the highly modified male antennal first flagellomere having a variable process, and is further divided into the S. coarctata subgroup (10 spp.) and S. punctata subgroup (25 spp.) (Shatalkin 1996;Evenhuis 2016).
The Chinese species belonging to the S. coarctata subgroup are reviewed in the present study. Prior to this study, only one species of this subgroup, S. coarctata Hendel, 1913, had been recorded from China (Yang and Wang 1998;Qilemoge et al. 2021). Here we describe three new species, and record two further species for the Chinese fauna and one new to the South Korean fauna. A key to the species of the S. coarctata subgroup from Asia is provided.
Male terminalia were prepared by macerating the apical portion of the abdomen in heated 10% KOH solution for approximately 10 min, and then rinsing in distilled water. External structure and terminalia were examined using a Nikon SMZ745 stereoscopic microscope. After examination, the terminalia were transferred to fresh glycerin and stored in microvials pinned below the corresponding specimens.
Photographs were taken using a Canon 7D Mark II digital camera with a Canon micro lens MP-E 65 mm for habitus, and an Olympus BX51 microscope for terminalia. Figures were stacked with Helicon Focus v. 5.3 and assembled by Adobe Photoshop 2020. The distribution map was prepared using the online version of SimpleMappr (Shorthouse 2010). Terminology follows Evenhuis (2016) and Lonsdale (2020); we use the term "phallic plate" following Lonsdale (2020) to refer the structure posteroventral to the basiphallus, although the homology of this structure is arguable. Measurements were obtained using a calibrated micrometer. Distributional data are given from specimens examined in this study and from literature records; new distributional records are marked by asterisk (*); data from literature records (without specimen examination) are given the source.

Notes.
For an extensive treatment of the family, systematic considerations, definitions, a key to species-groups, and a checklist of global species, see Evenhuis (2016) and Lonsdale (2020).

The Strongylophthalmyia coarctata subgroup
Diagnosis. Recognized within the genus by the following characters: antennal first flagellomere of male modified, having variable antennal process; arista bare; fore femur of male simple, lacking thorn-like spicules dorsally. Diversity and distribution. This subgroup currently contains ten described species, most of which are distributed in the Oriental Realm, while one species occurs in the northeastern Palearctic and three species are endemic to Papua New Guinea (Evenhuis 2016(Evenhuis , 2020. Strongylophthalmyia coarctata Hendel was previously known from China (Taiwan). Five species, including 3 described herein, are now added to the Chinese fauna.
Distribution. China -Taiwan: Chiayi (Papp 2005), Kaohsiung (Rohlfien and Ewald 1972), Pingtung (Fig. 56). Remarks. This species was originally described based on "Mehrere ♀, 2♂" (syntype) from "Kankau (Koshun)" (now Hengchun, Pingtung, Taiwan, China) (Hendel 1913). According to Rohlfien and Ewald (1972), the type material of this species was preserved in the collection of SDEI and included two males and four females. Shatalkin (2007) redescribed this species based on a male and a female which he referred as "holotype" and "paratype", respectively, and mentioned that these specimens were deposited in the Museum für Naturkunde, Berlin, Germany (ZMHB). However, no such specimens could be found in the collection of ZMHB (J. Pohl, pers. comm.), and the collection of SDEI was unavailable to us during the present study. We therefore presume that the type material of this species is still kept in SDEI, and Shatalkin (2007) made an incorrect interpretation on its depository. The uses of the term "holotype" and "paratype" by Shatalkin (2007) did not constitute valid lectotype designations (ICZN 1999, Art. 74.7), therefore the status of the type specimens of this species should remain as syntypes.
Female unknown. Etymology. The specific epithet is derived from Latin corniculata, referring to the short conical antennal process of this new species.
Comparative notes. This new species is similar to S. gibbifera Shatalkin, 1993 from Vietnam in that both have an ovate first flagellomere with a small, short antennal process, and a fully hyaline wing. The new species differs from S. gibbifera in the following characters: anterior half of frons yellowish brown (frons entirely black in S. gibbifera); first flagellomere yellowish brown (yellowish brown with dorsal half dark brown in S. gibbifera); antennal process conical, with sharp apex (short and blunt in S. gibbifera); mid and hind femora narrowly dark brown subapically, hind tibia largely darkened (femora yellow with hind femur weakly darkened at apex, hind tibia darkened in middle in S. gibbifera).  . 15); antennal first flagellomere of male yellow, subrhombic, with a long slender process covered with dense black setulae (Figs 16,17); wing infumate, with large dark suffusion at apex (Fig. 19); mid and hind femora yellow with narrow dark brown ring subapically (indistinct on mid femur) (Figs 13, 14); hind femur of male with one thorn-like inner basal process; distiphallus nearly as long as phallapodeme, with small apical "glans" (Figs 22, 23).
Etymology. The specific epithet is derived from Latin flagell-and -cornis, referring to the long, whip-like antennal process of this new species.
Distribution. China -Yunnan: Gejiu, Lvchun, Mengla (Fig. 56). Comparative notes. This new species resembles S. shatalkini Iwasa & Evenhuis, 2014 from Papua New Guinea and S. stylocera Shatalkin, 1996 from Philippines by having the long and slender antennal process. The new species dif- Figure 24. Strongylophthalmyia narwhal Evenhuis, 2020, non-type male, habitus, lateral view. Scale bar: 1 mm. fers from S. shatalkini in the following characters: frons yellow (entirely black in S. shatalkini); antennal first flagellomere of male subrhombic, with antennal process 4.8× as long as first flagellomere (ovate, with antennal process 4× as long as first flagellomere in S. shatalkini); femora yellow with mid and hind femora narrowly dark brown subapically (femora uniformly dark brown in S. shatalkini); wing with distinct large dark suffusion at apex, and R 4+5 and M 1+2 slightly convergent apically (wing with broad median transverse band and faint small apical suffusion, and R 4+5 and M 1+2 almost parallel in S. shatalkini). The new species can be separated from S. stylocera in the following characters: frons yellow (entirely black in S. stylocera); antennal process of male with dense dark setulae (with white setulae in S. stylocera); wing with distinct large dark suffusion at apex (wing hyaline in S. stylocera); abdomen with a large median yellow patch on syntergite 1+2 in male (uniformly black in S. stylocera). Diagnosis. Generally shiny blackish brown (Fig. 24); antennal first flagellomere of male yellowish brown with apical half darkened, round, with a long, thick, sword-like process (Figs 26,27); wing infumate, with large dark suffusion at apex and narrow median transverse band at level of dm-m (Fig. 29); fore femur yellow with narrow brown ring subapically (Fig. 24); mid and hind femora yellowish brown, with apical half of mid femur and broad subbasal and subapical rings of hind femur dark brown (Fig. 24); hind femur of male with one wartlike inner basal process; distiphallus approx. 1.3× as long as phallapodeme, with small apical "glans" (Figs 32, 33).
Distribution. China -Yunnan: Jinghong*, Lvchun* (Fig. 56). Thailand -Chiang Mai: Chiang Mai (Evenhuis 2020).  Remarks. This species was described based on a male holotype from Chiang Mai, Thailand (Evenhuis 2020). Newly available specimens from Yunnan, China are identical in most of the features described by Evenhuis (2020), but differs in the following aspects: (i) gena blackish brown as general body color; (ii) both wings with narrow median transverse band at level of dm-m; (iii) legs yellow to yellowish brown, with basal half of fore coxa, narrow subapical ring of fore femur, apical half of mid femur (except extreme apex), broad subbasal and subapical rings of hind femur, mid and hind tibiae (except bases and apices) and tarsomeres 4 and 5 brown to dark brown.

Remarks.
The male genitalia of this species were illustrated by Shatalkin (1996) and Krivosheina (1999) and are described here for the first time. This species was previously reported from the Russian Far East (Shatalkin 1996;Krivosheina 1999). Considering the new distributional records from China and South Korea, this species seems to be widely distributed in the eastern Palaearctic Realm.   Ground, 1429m, 2019. Paratypes. Same collection data as for holotype (1♂2♀, CAU).

Comparative notes.
This new species is similar to S. corniculata sp. nov., but can be distinguished from it in the following characters: frons black, at most anterior margin slightly paler (anterior half of frons yellowish brown in S. corniculata sp. nov.); first flagellomere of male with a small, bump-like process (with a small, conical, apically acute process in S. corniculata sp. nov.); thorax with two posterior supra-alar setae (one in S. corniculata sp. nov.); apical section of M 1+2 straight (slightly arched in S. corniculata sp. nov.); distiphallus nearly half as long as phallapodeme (distinctly shorter than half of length of phallapodeme in S. corniculata sp. nov.).
This new species also resembles S. gibbifera Shatalkin, 1993, but differs in having a different color pattern on the frons, first flagellomere, and the mid and hind femora and hind tibia, and in the different shape of the antennal process.

Discussion
The present study is part of our ongoing taxonomic study of the Chinese Strongylophthalmyiidae, documenting the Strongylophthalmyia coarctata subgroup from China, including three known species (two newly recorded in China) and three new species. All species are keyed.
The main characters currently used to distinguish species in the S. coarctata subgroup include body color (including color patterns on antenna and wing), male antennal morphology, and the inner basal process on male hind femur. In this study, we newly described the male genitalia of most Chinese species, and found that the morphology of the external genitalia, phallapodeme, and distiphallus differed among species in this subgroup: the external genitalia are short and broad in some species, while in others they are long and narrow; the phallapodeme is straight or clearly curved, and the relative length of the distiphallus varies among species; the distiphallus of different species has different forms of tricha on the membrane and apical "glans", and the apical "glans" is absent in S. corniculata sp. nov. and S. tangwangana sp. nov. These male genital characters are useful for species-level identification. In addition, the thoracic chaetotaxy varies between species, which may also be helpful in identifying female specimens that lack male-specific features.
The S. coarctata subgroup has high diversity in the Oriental Realm. However, most of the specimens currently available to us were collected from several scattered localities in China. There is no doubt that a considerable number of other species could be discovered in China (especially in southern China) following more thorough field investigations.