New genera of Australian stiletto flies (Diptera, Therevidae)

Abstract Two new stiletto fly genera of Agapophytinae (Diptera: Therevidae) are described from Australia. Sidarena gen. n. comprises six new species (Sidarena aurantia sp. n., Sidarena flavipalpa sp. n., Sidarena geraldton sp. n., Sidarena hortorum sp. n., Sidarena macfarlandi sp. n., and Sidarena yallingup sp. n.) and is largely endemic to Western Australia. Zelothrix gen. n. is described based on two species; Zelothrix warrumbungles sp. n. is a locally abundant species in Eastern Australia, while Zelothrix yeatesi sp. n. is restricted to southwestern Western Australia. These sister genera are likely closely related to Taenogerella Winterton & Irwin and Actenomeros Winterton & Irwin.

Numerous publications describing new subfamilies, genera and species of Australian therevids have been published over the last 10 years (e.g., Ferguson et al. 2013Ferguson et al. , 2014Winterton 2007aWinterton -d, 2009Winterton , 2011aWinterton and Ferguson 2012;Winterton and Lambkin 2012;Lambkin and Turco 2013) including overarching phylogenies of the family by Lambkin et al. (2009) and Winterton et al. (2016), yet new genera and species continue to be discovered and described. Herein we describe two new genera of agapophytine therevids from Australia, Sidarena gen. n. (Figs 1-2) and Zelothrix gen. n. (Fig. 3). Both genera were recovered as sister groups (both identified as 'undescribed genus S') in the recent paper on therevid phylogeny by Winterton et al. (2016) and appear closely related to genera such as Taenogerella Winterton & Irwin and Actenomeros Winterton & Irwin. The new genera are diagnosed and keys to species are presented for each.

Materials and methods
Adult morphological terminology follows Cumming and Wood (2009) with genitalic morphology as modified by Winterton et al. (1999a,b) and Winterton (2006). Genitalia were macerated in 10% KOH to remove soft tissue, then rinsed in distilled water and dilute glacial acetic acid, and dissected in 80% ethanol. Genitalia preparations were placed in glycerine in a genitalia vial mounted on the pin beneath the specimen. Specimen images were taken at different focal points using a digital camera and subsequently combined into a serial montage image using Helicon Focus software. All new nomenclatural acts are to be registered in ZooBank (Pyle and Michel 2008). Types are deposited in the following institutions and collections: Australian National Insect Collection (Canberra) (ANIC), Western Australian Museum (Perth) (WAM), California Academy of Sciences (San Francisco) (CAS), California State Collection of Arthropods (Sacramento) (CSCA), Canadian National Insect Collection (Ottawa) (CNC), Queensland Museum (Brisbane) (QM). Numbers quoted with individual specimens as MEI000000 are unique identifiers in the therevid database MANDALA and are attached to each specimen as a yellow or white label (Kampmeier and Irwin 2009). Material examined lists were exported from MANDALA. Abbreviations in text: notopleural setae (np); supra alar setae (sa); postalar setae (pa); dorsocentral setae (dc); scutellar setae (sc).
Diagnosis. Both sexes with eyes widely dichoptic; multiple poorly defined rows of postocular macrosetae present dorsally in both sexes; antennal scape lacking macrosetae along medial surface, scape shorter then head length; flagellum conical, tapering to a terminal arista; parafacial setae absent; one pair of scutellar macrosetae, most other scutal macrosetae variable in number; velutum patches absent on femora and sparsely   present ventrally on gonocoxites; single anteroventral seta present apically on hind femur; wing slightly to dark infuscate with maculae, cell m 3 open to wing margin; abdomen narrow elongate; male abdomen typically with silver velutum; male genitalia with articulating inner gonocoxal process well developed; outer gonocoxal process well developed and rounded; gonocoxal apodeme short and rounded; gonostylus narrow apically; gonocoxites lacking medial atrium; aedeagus with distiphallus broad apically, not directed ventrally at apex; epandrium shape quadrangular; ventral apodeme of parameral sheath forked. Female tergite 8 with broad anteromedial process; three spermathecae, ducts joining to spermathecal sac duct; spermathecal sac present (Fig. 28B).
Comments. Sidarena gen. n. is mostly endemic to Western Australia and is distinctive in general appearance, with male eyes widely dichoptic, numerous bristles on the occiput and often with grey metallic pubescent stripe medially on the scutum (often adjoining broad matte black-brown pubescent stripes laterally). The presence of these characters alone differentiates this genus from all other genera in the subfamily. Similar genera to Sidarena gen. n. include Squamopygia Kröber, Ectinorhynchus Macquart and Zelothrix gen. n. The new genus can be quickly differentiated from Squamopygia by the much shorter scape (narrowly elongate cylindrical in Squamopygia), and the wing not distinctly banded (two black bands in Squamopygia). Sidarena gen. n. is separable from Ectinorhynchus by the absence of a medial atrium in the male gonocoxites (present in Ectinorhynchus) and separable from Zelothrix gen. n. by a single scutellar macroseta (two macrosetae in Zelothrix gen. n.) and three spermathecae (two in Zelothrix gen. n.). The male genitalia are remarkably uniform throughout the genus. A single species is herein described from Queensland while the remaining species are from Western Australia.
Etymology. The genus name is derived from the Greek Sideros, meaning iron, referring to the broad metallic-grey stripe typically present on the thorax; and arena, referring to its habit of landing in sandy patches. Gender is feminine.
Key to species of Sidarena gen. n.
Comments. Sidarena aurantia sp. n. is known only from a series of males collected in Malaise traps in northern Western Australia. The yellow-orange abdomen is highly distinctive for this species, and it is very similar to S. macfarlandi sp. n. There are subtle differences between the two species, which at this stage, based on the material examined, we recognise as separate species. The abdomen of S. aurantia sp. n. is more uniformly orange (darker on anterior tergites in S. macfarlandi sp. n.), while the lower half of the pleuron, coxae and hind femora are darker in S. aurantia sp. n. The female is unknown for this species.
Etymology. The specific epithet is a Latin adjective in the nominative feminine singular, meaning orange-coloured, referring to the body colouration. Paratype. AUSTRALIA: Queensland: female, same data and mounted with holotype (CSCA) (MEI028782).
Diagnosis. Medium sized fly with light brownish-grey coloured thorax; abdomen base colour dark brown; scutum brown with light grey dorsocentral stripes; occiput overlain with tan-grey pubescence; wing slightly infuscate, darker along wing veins.
Description. Body length. 6.5 mm (male), 7.0 mm (female). Head. Light browntannish grey pubescent; frons darker along eye margin (as a spot in female), admixed with sparse dark setae, especially above antennal socket; occiput convex with dark postocular setae not arranged in rows in either sex, setae of similar length in both sexes, dark setae extending onto gena where they are admixed with paler setae; antennal scape longer than pedicel and flagellum combined, distinctly thicker; scape yellow with brownish suffusion laterally, numerous robust dark setae laterally; pedicel brownish with dark setae; flagellum brown, conical, darker apically; mouthparts yellow with white setae. Thorax. Scutum with extensive dark brown matte pubescence, orange pubescence laterally and on postpronotal lobe, distinct light grey dorsocentral stripes along entire scutum length; scutal pile very fine and sparse; scutellum yellow with sparse grey pubescence; pleuron tan-grey pubescent with fine white setae confined to anepisternum and katatergite. Coxae yellow, overlain with grey pubescence; legs entirely yellow with black macrosetae; chaetotaxy: np, 4; sa, 2; pa, 1; dc, 4; sc, 1; wing hyaline with brownish tint. Abdomen. Tergites dark brown to black with yellow laterally, sternites yellow; all segments with sparse short setae, lateral setae white in male,  especially on anterior segments. Male terminalia. (Fig. 9) Epandrium longer than wide, with medium length black setae over entire surface; hypoproct rounded apically; gonocoxite ovate, outer gonocoxal process elongate and rounded, reaching half the distance to the tip of the inner gonocoxal process; inner gonocoxal process slightly spatulate at apex, extending to tip of gonostylus; gonostylus with a brush of light brown setae along inner surface; gonocoxite with elongate dark brown setae on lateral surface, denser over area ventrad of outer gonocoxal process; aedeagus typical of other species in the genus. Female terminalia. Short white setae dorsally on 4/5 ths of tergite 8; tergite 8 longer than broad; sternite 8 setose surface thinly sclerotized, ovoid in shape, narrower posteriorly; six acanthophorite A1 setae strong, 11 longer, thinner A2 setae directed ventrally.
Comments. Sidarena flavipalpa sp. n. is the only species of the genus found in eastern Australia. The species is only known from a pair collected in copula, and mounted together on the same pin; the holotype is the male, while the female is the paratype. This species is also distinctive by the scutal pubescent pattern, which is different from other species in the genus.
Etymology. The specific epithet is a noun in apposition derived from combining the Latin adjective flavus, meaning yellow, and noun palpus, meaning feeler, referring to the colour of the palpi. Diagnosis. Relatively small and slender species; scape grey pubescent, relatively narrow; pleuron uniform grey pubescent; abdomen dark brown-black; scutum with broad metallic grey stripe with medial brown suffusion; wing with faint infuscation, darker anteriorly and along veins; legs brown.
Description. Body length. 5.5 mm (male). Head. Occiput silver-grey pubescent with two rows of elongate postocular setae; frons flat, dark brown pubescent admixed with elongate black setae, especially just above antennal socket; pubescence also as black line along eye margin and silver spot lateral to antennal socket; face silver pubescent; gena silver-white pubescent with fine, white, elongate setae; antenna as long as head length, scape similar width to pedicel and flagellum and as long as both combined, brown with grey pubescence with extensive black setae on outer surface; flagellum brown pubescent, tapered to dark arista; mouthparts dark brown with black setae. Thorax. Dark base colour overlain with extensive grey pubescence; scutum overlain with pubescence as broad brown lateral stripes and broad metallic-grey stripe medially with brown suffusion along axis; scutellum yellowish with grey pubescence; pleuron mostly grey pubescent, lacking  setae except anepisternum and katatergite which have scattered short, white setae; coxae dark grey pubescent; legs uniformly brown with black setae; chaetotaxy: np, 4; sa, 1; pa, 1; dc, 3; sc 1; wing uniformly tinted infuscate, venation dark. Abdomen. Dark brownblack with cream-yellow areas laterally and on tergite 1, extensive silver velutum on at least tergites 1-4 in male, velutum not unidirectional, but with triangular pattern depending on angle viewed; thin setae present on all segments, black medially and posteriorly, white laterally and anteriorly. Male terminalia. (Fig. 11) Epandrium longer than wide, setae more robust laterally; cerci distinctly separate, ovoid; tergite 8 quadrangular with short robust setae laterally; gonocoxite wider than long; outer gonocoxal process elongate, pointed; inner gonocoxal process elongate, its apex protruding posteriorly to apex of gonostylus but more thinly sclerotized and slightly spatulate apically; gonostylus slender with scattered black setae anteriorly at about 1/3 distance from base to apex; ventral lobe broad and rounded; hypandrium connected to gonocoxite along anterior edge; aedeagus shape similar to other species in genus.
Comments. Sidarena geraldton sp. n. is a western species known only from the male holotype collected from Geraldton, Western Australia. This is a relatively diminutive species with dark legs, abdomen and narrow wings.
Etymology. The specific epithet is the unaltered place name of the type locality for this species; a noun in apposition. Diagnosis. Medium sized flies; thorax yellowish dorsally on pleuron, darker ventrally, scutum with broad grey strip and narrow medial brown suffusion; abdomen dark brown, yellow laterally; wing hyaline, faintly infuscate anteriorly and along veins; legs yellowish with dark suffusion; male postocular setae variable in length but often elongate.
Comments. Sidarena hortorum sp. n. is a western species closely related to S. aurantia sp. n. and S. macfarlandi sp. n. based on body colouration and scutal pattern.
Etymology. This species is a patronym named in honour of Fred and Jean Hort, field naturalists and photographers who enthusiastically document the flora and fauna of Western Australia. Diagnosis. Abdomen distinctly orange; wing slightly mottled; legs dark yellow with brown suffusion on hind femur; pleuron dark yellow dorsally; abdominal tergite 1 with dark brown markings.
Comments. Sidarena macfarlandi sp. n. is similar in appearance to S. aurantia sp. n. based on body colouration, especially the abdomen (see comments above).
Etymology. This species is named after the collector, Noel McFarland, of this and other species of Sidarena in Western Australia.     Diagnosis. Wing dark mottled infuscate; scutal macrosetae elongate, legs dark brown; abdomen dark brown; genal pile uniformly dark.
Description. Body length. 7.5 mm (male), 8.5 mm (female). Head (Fig 17-18). Grey-silver (male) or yellow-silver (female) pubescent; male occiput convex with silver-grey and matte black pubescence (depending on angle viewed); postocular setae not arranged in rows, setae variable in length, some elongate; frons flat with elongate black, scattered setae, at midpoint of the frons is a small dark patch of dark brown pubescence set against eye margin; gena with dark setae; face golden (female), silver (male) pubescent, without setae; antennae light yellowish-brown; palpus brown with dark setae; antenna light yellow-orange, scape wider than pedicel and flagellum, with dark setae on outer lateral surface, longer than pedicel and flagellum combined; flagellum orange, tapered to a dark brown arista. Thorax. Scutum with distinct matte black (gold when viewed laterally) stripes laterally, broad medial stripe greyish in male, yellowish-grey in female, narrow dark brown suffused stripe along axis in male; postpronotal lobe orange; scutal macrosetae elongate, black, sparse thin scutal pile other-wise; pleuron dark yellow, darker ventrally and on coxae, with sparse covering of grey pubescence; sparse elongate, thin black setae on anepisternum and katatergite; scutellum pale yellow-orange with grey pubescence; chaetotaxy: np, 3; sa, 2; pa, 1; dc, 6-7; sc 2; wing dark mottled infuscate; coxae dark brown with grey pubescence; femora dark brown; rest of legs light brown. Abdomen. Dark brown, dorsally black with silver velutum on tergites 2-5 (more extensive in male), velutum pattern not unidirectional and silver pattern changes depending on angle viewed; anterolaterally on tergite 1 is a small patch of orange. Male (Fig. 19) and female (Fig. 20) terminalia. Similar to other members of the genus.
Comments. The mottled wing of S. yallingup sp. n. is highly distinctive and easily identifies it among the other species with the metallic grey stripe on the scutum. There is more sexual dimorphism in this than in other species. This species appears to be closely related to S. geraldton sp. n. based on overall body colouration and wing pattern.
Etymology. The specific epithet is the unaltered place name Yallingup (which is an Aboriginal word meaning 'Place of Love') for a location in southwestern Western Australia where this species was collected; a noun in apposition.
Included species. Z. warrumbungles sp. n. and Z. yeatesi sp. n. Comments. Zelothrix gen. n. is a distinctive genus with a disparate distribution. Similar genera include Squamopygia Kröber, Taenogerella Winterton & Irwin and Sidarena gen. n. This new genus can be differentiated from Squamopygia and Sidarena gen. n. by the presence of two scutellar macrosetae and a medial atrium in the male gonocoxites. The wing is extensively patterned in Zelothrix gen. n. but not banded as in Squamopygia. Zelothrix gen. n. is separable from Taenogerella by the latter having a downward directed distiphallus in the male genitalia and three spermathecae (two in Zelothrix gen. n.). A significant departure from the female genitalic complement of three spermathecae typically found in Agapophytinae, is that Zelothrix gen. n. only has two spermathecae, a condition found in Therevinae. No other genus of Agapophytinae has two spermathecae, although the distantly related agapophytine genus Bonjeania Winterton & Skevington has only a single spermatheca (Winterton et al. 2000).
Zelothrix warrumbungles sp. n. is a locally highly abundant species found mainly in Warrumbungle National Park (New South Wales) (Fig. 4), while Z. yeatesi sp. n. is a rarely collected species endemic to Porongurup National Park (Western Australia). The two species are very similar in appearance.
Etymology. This name is derived from the Greek, Zelos-emulation, and thrixhair, for the setal pile on the female abdomen. Gender is feminine.
Key to species of Zelothrix gen. n.: Diagnosis. Forefemur dark brown; male frons predominantly silver pubescent immediately above antennal socket; antenna greater than 1.5x head length.
Description. Body length. 7.5 mm (male), 8.5 mm (female). Head. (Figs 21-22) Silver-grey pubescent; ocellar tubercle black, raised (prominent in male); frons flat, with only a few black setae above the antennal socket, silver and black pubescent in male, matte black, silver and gold patterned in female; occiput silver-gold pubescent,  concave with a single row of black postocular setae dorsally in male, two rows in female; gena silver pubescent admixed with pale setae; parafacial silver in male, silver and matte black in female; palpus narrow, pointed apically, with brown with black setae;. Antennal scape elongate and cylindrical, orange, with erect black setae on all surfaces, slightly thinker than flagellum and length equalling length of combined pedicel and flagellum; flagellum elongate and cylindrical, brown pubescent with distinct angled arista at apex. Thorax. Scutum and scutellum gold-silver pubescent, scutum with three distinct dark brown stripes, medial stripe extending onto scutellum; chaetotaxy: np, 4; sa, 2; pa, 1; dc, 3; sc, 2; pleuron base colour black, overlain with dense greenish-silver pubescence extending onto coxae; thin white hairs on anepisternum and katatergite; femora bright yellow, forefemur mostly with dark brown to black suffusion; tibiae and tarsomeres 1 and 2 dark yellow, brown apically; remaining tarsomeres dark brown; wing distinctly infuscate with extensive mottled pattern; venation dark. Abdomen. Slender, elongate, bright yellow with small dark brown area anteromedially on tergites in male, tergites more extensively dark brown in female and overlain with sparse grey pubescence; sparse thin elongate setae on all segments, mostly pale, but darker dorsomedially and on terminalia. Male Terminalia. (Fig. 23) Epandrium longer than wide, slightly tapered posteriorly, sclerotised posterolaterally, setae sparse, more elongate laterally; cercus relatively small; gonocoxites rounded with short round outer gonocoxal process; hypandrium small and fused to gonocoxites anteriorly; gonocoxal apodemes small and rounded; setae on gonocoxites sparse, elongate and erect, with sparse velutum ventrally on gonocoxite; inner gonocoxal process and gonostylus narrow and curved medially; ventral lobe elongate and rounded apically; dorsal apodeme of parameral sheath 'T'-shaped; ventral lobe broad, not forked and projecting beyond dorsal apodeme; distiphallus broad, irregularly shaped dorsally, small spines apically; lateral ejaculatory apodemes narrow and angled posteriorly, basiphallus small. Female terminalia. Similar to the other species in this genus.
Comments. Zelothrix warrumbungles sp. n. is a distinctive, elegant and abundant species in the type locality during the late summer months, and in some years may be the most commonly encountered species of stiletto fly during this time.
Etymology. The specific epithet is the unaltered place name Warrumbungles (which is an Aborignal name for this mountain range, meaning "crooked mountains") referring to the mountain range where this species was collected; a noun in apposition.    Diagnosis. Forefemur dark yellow; male frons black and silver pubescent immediately above antennal socket; antenna less than 1.5x head length.
Description. Body length. 6.0 mm (male), 6.5 mm (female). (Figs 24-25) Similar to Z. warrumbungles sp. n. except as follows: Antenna shorter, scape slightly wider; frons of male with matte black pubescence more extensive above antennae socket; scutal chaetotaxy: np, 4; sa, 1-2; pa, 1; dc, 4; sc, 2; foreleg dark yellow; male abdominal tergites with more extensive dark markings medially. Male (Fig.  26) and female (Fig 27, 28A) terminalia. Very similar to the other species in this genus. Female tergite 8 with anterior process relatively narrow; broad band of elongate setae directed posteriorly on both tergite 8 and sternite 8; furca broadly tear-drop shaped Comments. Zelothrix yeatesi sp. n. is very similar in body colour and wing patterning to Z. warrumbungles sp. n., but is much less commonly collected. The shape and vestiture of the frons and antennal shape differentiate this species.
Etymology. This distinctive species is a patronym named in honour of our colleague, friend and oft mentor, Dr David K. Yeates.