Iranotrichia gen. n., a new genus of Scenopinidae (Diptera) from Iran, with a key to window fly genera of the world

Abstract An unusual new genus of Scenopinidae, Iranotrichia gen. n., comprising two newly discovered species (Iranotrichia insolita sp. n. and Iranotrichia nigra sp. n.), is described from Iran. Iranotrichia gen. n. are scenopinine window flies with a habitus reminiscent of certain bee fly genera (Bombyliidae), based on colouration and elongate mouthparts and antennae. The phylogenetic placement of this distinctive new genus is discussed and a dichotomous key to world genera is presented. The genus name Kelseyana nom. n. is proposed to replace Caenoneura Kröber, 1924, which was found to be preoccupied by Thomson (1870: 270) (Hymenoptera) and Kirby (1890: 136) (Odonata).


Introduction
Window flies (Diptera: Scenopinidae) are a small family (ca. 420 species in 26 genera) of flies with an adult body size rarely exceeding 5.0 mm. Scenopinids are distributed throughout all major biogeographical regions, and with few exceptions, most genera are confined to a single biogeographical region (Kelsey, 1973). This family is placed in the therevoid clade, comprising families such as Therevidae (stiletto flies), Apsilocephalidae and Evocoidae (Winterton, 2008;Trautwein et al., 2010). A close relationship between Scenopinidae and Therevidae has been previously identified based on the secondarily segmented characteristic of the larval abdomen (Woodley, 1989).
Iranotrichia gen. n. is described herein from northern Iran, comprising two species, I. insolita sp. n. and I. nigra sp. n. This new genus is morphologically very similar to other scenopinine genera such as Metatrichia Coquillett, 1900, Kelseyana nom. n. (= Caenoneura Kröber, 1923 and Pseudomphrale Kröber, 1913. This group of genera is differentiated by other scenopinine genera based on the following characteristics: wing vein M 1 fused to vein R 5 before wing margin, mouthparts well developed, scutum with extensive pile (often scale-like), abdomen broad and flattened in both sexes with limited sexual dimorphism, male genitalia with gonocoxal apodemes relatively broad, and female acanthophorite spines absent. Metatrichia is a cosmopolitan genus containing 16 extant and one fossil species. (Kelsey 1969;Krivosheina and Krivosheina 1999;Winterton and Woodley, 2009;Yeates and Grimaldi, 1995). The morphological differences between Metatrichia and Pseudomphrale are not clear, and the validity of this distinction has been questioned previously (Krivosheina and Krivosheina, 1996;Winterton and Woodley 2009). Iranotrichia gen. n. is easily differentiated from all other scenopinine genera based on the characters above, as well as the elongate antennae and mouthparts, subterminal antennal style and greatly elongate distiphallus in the male genitalia. This new genus is described and figured herein, with a key to the 25 extant scenopinid genera of the world presented. The genus name Kelseyana nom. n. proposed to replace Caenoneura Kröber, which was found to be is preoccupied by Thomson (1870: 270) (Hymenoptera) and Kirby (1890: 136) (Odonata).

Materials and Methods
Genitalia were macerated in 10% KOH at room temperature for one day to remove soft tissue, then rinsed in distilled water and dilute acetic acid, and dissected in 80% ethanol. Preparations were then placed into glycerine, with images made with the aid of a digital camera mounted on a stereomicroscope. Genitalia preparations were placed in glycerine in a genitalia vial mounted on the pin beneath the specimen. Terminology follows Winterton (2005) and Winterton and Woodley (2009). In contrast to the scenopinid subfamilies Proratinae and Caenotinae, the male terminalia of Scenopininae are rotated 180°. To avoid confusion with terminology and comparative homology, structures are described and labeled as they are in related flies with terminalia not rotated; therefore the ventral apodeme of the aedeagus described herein is physically located dorsally. The following collection acronyms are cited in the text: California Academy of Sciences, San Francisco, California, USA (CAS), California State Collection of Arthropods, Sacramento, California, USA (CSCA), Iranian Research Institute of Plant Protection, Tehran, Iran (IRIPP), and the National Museum of Natural History, Smithsonian Institution, Washington DC, USA (NMNH). Specimen images were taken at different focal points using a digital camera and subsequently combined into a serial montage image using Helicon Focus software. High-resolution digital images were deposited into Morphbank with embedded URL links within the document between descriptions and Morphbank images. All new nomenclatural acts and literature are registered in Zoobank (Pyle and Michel, 2008).  . Head higher than long, sub-spherical, female with broad, raised postocular ridge; antenna elongate, cylindrical, length 0.6-1.2× head length; antennal style subterminal, flagellum broadly rounded to truncate apically, not notched; frons relatively flat, not protruding anteriorly; mouthparts greater than head length, projecting anteriorly; scutum with dense pile of semi-appressed, silver-white lanceolate setae, all directed towards a single posteromedial point (Figs 2-3, 6); wing vein M 1 joining with R 5 (Fig. 1A), cell r 5 petiolate to wing margin; wing vein M 2 absent; costal margin ending at vein R 5 ; abdomen broad, width equal to thorax; tergite 2 sensory setae well defined and two circular patches. Male genitalia: rotated 180°; tergite 7 and sternite 7 broad and separate, not ring-like; male epandrium split medially as two sclerites, halves sub-circular or sub-triangular; epandrium not covering gonocoxites ventrally; hypandrium as, paired sclerites, narrow paddle-shape with short setae along posterior margin; gonostylus well developed, irregular shaped, dark sclerotized and irregular spinose marginally; aedeagus protruding anteriorly from epandrium only a relatively short distance; gonocoxite irregularly shaped and mostly reduced; gonocoxal apodeme relatively thickened, broadly triangular with medial braces joining with aedeagus; aedeagus with lateral aedeagal bulb present, sometimes well developed; distiphallus bifid, recurved dorsally at base then greatly elongate and coiled. Female genitalia: tergite 9+10 narrow and band-like, acanthophorite spines absent; sternite 8 slightly longer than tergite 8, broadly acuminate posteriorly; furca a dark-sclerotized ring with narrow posterolateral arm, connected posteromedially with 'Y'-shaped sclerotized bridge between furca and anterior margins of tergite 9+10; two sclerotized spherical spermathecae; spermathecal sac simple, connected to bursa medially immediately anterior to spermathecal ducts.
Etymology. The genus name is derived from the type location of members of this genus; Iran, -trichia (Greek: hair), referring to the setal pattern and has frequently been used historically to formulate to scenopinid generic names.
Comments. This genus is placed in Scenopininae based on the rotated genitalia, wing venation and shape of the tergite two setal patches. The general habitus of members of this new genus is very reminiscent of certain genera of Bombyliidae. Iranotrichia gen. n. is morphologically very similar to Metatrichia and Pseudomphrale, but can be separated from these and other Scenopinidae based on the greatly elongate and often coiled bifid distiphallus, elongate antennae and mouthparts, flagellum not notched apically and with style subapical on outer surface. The elongate antennae and mouthparts and distiphallus are characteristic of Iranotrichia; although such elongation of these structures is sometimes found in proratine genera such as Prorates and Jackhallia, it is not found elsewhere in Scenopininae. Some species of Pseudomphrale and Metatrichia have elongated mouthparts (e.g. M. palaestinensis (Kröber, 1937), M. freidbergi Krivoshiena andKrivosheina, 1999, andP. longirostris Becker, 1913) (Krivosheina and Krivosheina 1999;Kelsey 1969) about half as long as species of Iranotrichia gen. n. Possibly of little phylogenetic significance, but useful for differentiating Pseudomphrale from Iranotrichia gen. n. and Metatrichia is that all specimens of Pseudomphrale species are between 1.6 and 4.0 mm body length, while specimens of Iranotrichia and Metatrichia are rarely less than 4.0 mm (Kelsey 1969;Krivosheina 1996, 1999;Winterton and Woodley 2009). A greatly elongate, coiled distiphallus is also present in M. palaestinensis (cf. Kröber 1937 andKelsey 1969). Both species of Iranotrichia gen. n. are known only from a single collecting event in Ghazvin province, Iran where I. insolita sp. n. is apparently far more abundant than I. nigra sp. n.
Diagnosis. Head, thorax, abdomen and legs with extensive areas of yellow and/or white; combined length of scape and pedicel equal to length of flagellum; scutellum white with yellow suffusion anteromedially; terminalia yellow; epandrium elongate and sub-triangular; distiphallus of male as long or longer than body when uncoiled; distiphallus arms without spinose process. . Head. Male frons glossy black, dark yellow around base of antennae; female frons white with broad dark brown stripe medially extending ventrally from ocellar tubercle, suffused near base of antennae; frons of both sexes with short setae, setae white near base of antennae; ocellar tubercle black, raised in male, flat in female; occiput glossy black (male) or white-yellow with black medially around occipital foramen (female); occiput with sparse, short yellowish setae; gena yellow, raised as ridge along eye margin, sparse short pale setae; parafacial white to yellow, oral cavity with dark yellow sclerotized plates either side of dark medial strip; mouthparts elongate, dark brown, labellum narrow, proboscis flattened laterally (in dried specimen); palpus dark brown, short; antenna slightly longer than head length, dark yellow basally, dark brown distally; short white setae on scape and pedicel; scape 2-3X  pedicel length, combined scape and pedicel length equal to length of flagellum; flagellum truncated apically. Thorax. Scutum black, pale white to dark yellow areas marginally (i.e. postpronotal lobe and post-alar callus), more extensive in female and additionally with yellow on anterior part of scutum adjacent to postpronotum and medially on posterior part of scutum; scutal pile dense with three indistinct vittae anteriorly on prescutum formed by unidirectional parting of setae; scutellum matte white, yellow anteromedially, sparse pale setae covering marginally; pleuron black with white to dark yellow dorsally on anepisternum and katepisternum, and around base of wing (pale area more extensive in female); white setae on katepisternum; coxae black to brown; legs yellow, femora frequently with brown suffusion basally on posterior surface; short pile of white-yellow setae on legs, longer on posterior surface of femora; distal tarsomeres suffused with brown; haltere stem brownish, knob white; wing milky hyaline from sparse microtrichia; venation cream-white. Abdomen. Glossy black, each segment with dark yellow laterally and thick white band along posterior margin, segments 6-8 with dark yellow more extensive along posterior margin, replacing white band; white setae on all segments, longer laterally; terminalia dark yellow with long pale setae. Male genitalia (Fig. 4A-B). Epandrium lobes elongate and sub-triangular, dark sclerotized margins around bases of cerci; subepandrial sclerite extending posteriorly beyond cerci, emarginate posteriorly; hypandrium lobes relatively small and paddle-like with posterior margin of setae; gonocoxite with dark sclerotized, dorsal process immediately ventral to subepandrial sclerite; gonocoxal apodeme broadly flattened, curved medially; ejaculatory apodeme relatively elongate, directed anteriorly; lateral aedeagal bulbs round; distiphallus extremely elongate, arms thick and separate basally, recurved dorsally, arms proximal before end of epandrium, distal portion greatly narrowed and highly coiled, easily longer than body length when uncoiled. Female genitalia (Fig. 5A). Sternite 8 with posterior edge broadly acuminate; spermathecal ducts with valves associated with large membranous sacs. Etymology. The specific epithet is derived from the Latin, insolitus-unusual, strange, and refers to the unusual appearance of this species.
Comments. Iranotrichia insolita sp. n. is a highly distinctive species with contrasting black and white-yellow markings; characteristics, which differentiate this species from I. nigra sp. n., among others, include the extremely elongate distiphallus and lack of spinose processes at the base of the distiphallus. The antennae and mouthparts are the longest of any scenopinid and are presumably associated with feeding at flowers. Diagnosis. Head, thorax, abdomen and legs black, with limited areas of yellow; combined length of scape and pedicel approximately 2/3 length of flagellum; scutellum black with yellow-white marginally; male terminalia dark; epandrium sub-circular; distiphallus of male sub equal to length of abdomen when uncoiled; distiphallus arms with spinose process basally.
Description. Body length: 4.5 mm [male]. Head. Male frons glossy black, dark yellow below base of antennae, short white setae above base of antennae; ocellar tubercle black, raised in profile; occiput glossy black with sparse, short yellowish setae; gena cream-white, raised as ridge along eye margin, sparse short pale setae; parafacial white to yellow with brown suffusion; oral cavity with dark yellow sclerotized plates either side of dark medial stripe; mouthparts elongate, dark brown, labellum narrow, proboscis flattened laterally (in dried specimen); palpus short, dark brown; antenna 0.6× head length, uniform dark brown; short white setae on scape and pedicel; scape 2× pedicel length, combined scape and pedicel length less than length of flagellum; flagellum tapered slightly apically. Thorax. Scutum black, yellow areas marginally (postpronotal lobe and post-alar callus); scutal pile dense; scutellum black, yellow-white marginally; pleuron black with white suffusion dor-  sally on anepisternum, and around base of wing; white setae on anepisternum and katepisternum; coxae black to brown with white setae; legs black, yellow apically on femora, basally on tibiae and basitarsi; short pile of white-yellow setae on legs, longer on posterior surface of femora; haltere stem brownish, knob white; wing milky hyaline from sparse microtrichia; venation cream-white. Abdomen. Glossy black, each segment with a thick white band along posterior margin, segments 6-8 with dark yellow more extensive along posterior margin, replacing white band; white setae on all segments, longer laterally; terminalia black with dark brown on epandrium, with long pale setae. Male genitalia (Fig. 4C-D). Epandrium lobes rounded and sub-circular, dark sclerotized margins around bases of cerci; subepandrial sclerite quadrangular; hypandrium lobes relatively well developed, paddlelike narrower anterior medial process, posterior margin with pale setae; gonocoxite dark sclerotized, with dorsal process immediately medial to subepandrial sclerite; gonocoxal apodeme very broadly, curved medially; ejaculatory apodeme spatulate, directed anteriorly; lateral aedeagal bulbs relatively large, each subdivided dorsoventrally into two chambers; distiphallus elongate, arms thick and separate basally, recurved dorsally, with ventromedially directed spinose process at base, arms overlap before end of epandrium, distal portion narrowed and coiled, not longer than body length when uncoiled.
Etymology. The specific epithet is derived from the Latin, nigra-black, dark, and refers to the overall dark colour of this species.
Comments. Iranotrichia nigra sp. n. is differentiated from I. insolita sp. n. by the shorter antennae, rounded epandrial lobes, shorter male distiphallus, secondarily subdivided lateral aedeagal lobes and presence of spinose processes at the base of the distiphallus. The female of this species is unknown. Type species. Caenoneura robusta Kröber, 1924: 75. Included species. Kelseyana nigra (Kelsey, 1969) comb. n., Kelseyana robusta (Kröber, 1924) comb. n. ber 0614213. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of NSF.