Review of Australasian spider flies (Diptera, Acroceridae) with a revision of Panops Lamarck

Abstract The Australasian spider flies (Diptera: Acroceridae) are reviewed, with all eight currently recognized genera diagnosed and figured. The panopine genus Panops Lamarck, 1804 from Australia and Indonesia is revised with four new species described, increasing the total number of species in the genus to nine: Panops aurum sp. n., Panops danielsi sp. n., Panops jade sp. n. and Panops schlingeri sp. n. Five species of Panops are redescribed: Panops austrae Neboiss, 1971, Panops baudini Lamarck, 1804, Panops boharti (Schlinger, 1959), comb. n., Panops conspicuus (Brunetti, 1926) and Panops grossi (Neboiss, 1971), comb. n. The monotypic genera Neopanops Schlinger, 1959 and Panocalda Neboiss, 1971 are synonymized with Panops. Keys to genera of Australasian Acroceridae and species of Panops, Helle Osten Sacken, 1896 and Australasian Pterodontia Gray, 1832 are included.


Introduction
Spider flies (also known as small-headed flies) (Diptera: Acroceridae) are a distinctive group of lower brachyceran flies characterized by unusual adult body shape and highly specialized larval biology as parasitoids of spiders. Adults are recognized as important pollinators of angiosperms ( Fig. 1), frequently as strong fliers with greatly elongate mouthparts for feeding in long corolla flowers, although some species have reduced or even vestigial mouthparts (Schlinger 1981(Schlinger , 1987. Acroceridae comprise approximately 520 species in 53 genera (Pape and Thompson 2010;Gillung and Winterton 2011) occupying most biogeographic regions. The family is presently classified into three extant subfamilies: Acrocerinae, Panopinae and Philopotinae (Schlinger 1981), although recent phylogenetic analyses using DNA sequence data suggest that Acrocerinae are polyphyletic and membership of that subfamily should be re-examined (Winterton et al. 2007). Larvae of Acroceridae are internal parasitoids of juvenile spiders, living internally within the opithsoma of the spider where they attach to the book-lungs of the host via their posterior spiracles. Upon completing development the mature, third instar larva emerges from the dead host before pupating (Schlinger 1987). There are exceptions though, with a Chilean species recorded as ectoparasitic on spiders (i.e. Sphaerops appendiculata Philippi, 1865 (Acrocerinae)) (Schlinger 1987), whilst Kerr and Winterton (2008) recently questioned the exclusivity of parasitism of spiders, describing a putative acrocerid planidium on an anystinid mite in Baltic Amber. The Australasian acrocerid fauna comprises all three subfamilies, although represented by relatively few genera. Two acrocerine genera (Ogcodes Latreille, 1797 andPterodontia Gray, 1832) are found throughout the region, and are considered cosmopolitan throughout all major biogeographic regions. Philopotinae are represented by an endemic genus in New Zealand (Helle Osten Sacken, 1896) (Paramonov 1955) and a recently described genus endemic to New Caledonia (Schlingeriella Gillung & Winterton, 2011).

Material and methods
Terminology follows  and Schlinger (1981). In most acrocerids, two crossveins span the area between the radial and medial sectors. The proximal crossvein is r-m, while the distal crossvein bisecting cell r 4+5 (between wing veins M 1 and R 4+5 , or rarely R 5 ) is referred to here as 2r-m following Hardy (1946) and Gillung and Winterton (2011). Annotations of collection label data are included where appropriate in brackets. The following collection codens are cited in the text: Australian Museum (AMS), Australian National Insect Collection (ANIC), California Academy of Sciences (CAS), Canadian National Collection of Insects (CNC); Greg Daniels private collection [to be ultimately deposited in the Australian Museum] (GDCB/AMS), Museum 6 Eye apilose, or sparsely or partially pilose; wing hyaline; crossvein 2r-m joining to stem R 4+5 (Fig. 2D)  Diagnosis. Usually large and densely pilose, body shape never arched; antennal flagellum elongate cylindrical to paddle-shaped, sometimes tapered but never stylate, usually lacking terminal setae; postpronotal lobes never meeting medially; wing venation complete to wing margin (rarely reduced), cells m 3 , d, bm and basal r 4+5 typically present, closed distally; tibial spines present (rarely absent); larvae exclusively parasitoids of mygalomorph spiders. Apsona Westwood, 1876;Leucopsina Westwood, 1876;Mesophysa Macquart, 1838;Panops Lamarck, 1804. Comments. Apsona is a monotypic genus endemic to New Zealand and can be readily differentiated from all other Panopinae based on the lack of tibial spines. Apsona shows little relationship to the rest of the Australasian Panopinae and shows remarkable similarity to the New World genus Eulonchus Gerstaecker, 1856, sharing numerous characteristics such as metallic green colouration, antennal shape, dense eye pilosity, elongate mouthparts, eyes contiguous below antennal base and absence of an alula (Paramonov 1955  vein compliment: M 1 , M 2 and M 3 present (M 3 fused with CuA 1 ); discal cell closed completely; medial veins reaching wing margin; cell m 3 present; CuA 1 joining M 3, petiolate to margin; CuA 2 fused to A 1 before wing margin, petiolate; wing microtrichia absent; anal lobe well-developed; alula weakly developed; abdominal tergites smooth, rounded, tergites raised along posterior margins; abdomen constricted anteriorly.
Comments. Leucopsina is an endemic Australian genus of contrastingly coloured yellow and black flies, with distinct sexual dimorphism between males and females; male having more pronounced constriction of the abdomen anteriorly. The body colouration, darkening of the costal wing margin and abdominal waist allows members of this genus to be convincing wasp mimics (Neboiss 1971). Leucopsina can be differentiated from all other acrocerid genera by the wasp mimicking habitus, elongate cylindrical flagellum, apilose eyes and elongate mouthparts. Neboiss (1971) provides a key to species of this genus. Leucopsina burnsi was originally described as a variety of Panops flavipes (=Mesophysa flavipes Latreille, 1811) but subsequently transferred to Leucopsina and thoroughly differentiated from L. odyneroides by Neboiss (1971).  (Latreille, 1811); M. ilzei Neboiss, 1971; M. tenaria Neboiss, 1971;M. ultima Neboiss, 1971.
Comments. Panops is the type genus for the subfamily Panopinae and includes some large metallic coloured species. The genus is endemic to Australia and neighbouring Papua region of Indonesia. The original concept of the genus was expanded to include species from the New World by some authors, but these have subsequently been placed in the separate and distantly related genus Lasia Wiedemann, 1824 (e.g. Lasia metallica Rondani, 1863; Lasia ocelliger (Wiedemann, 1830)). Bequaert (1931) and later Neboiss (1971), discuss the historically confused and intertwined generic concepts of Lasia and Panops (sometimes including Mesophysa) in previous treatments of the group by various authors. Based on a series of characters, it is clear that those Australasian species are placed in Panops or Mesophysa, while the New World species are placed in Lasia. In his description of Neopanops, Schlinger (1959) suggested that the genus was closely related to Panops and provided an extensive list of characters distinguishing the two. Similarly, Neboiss (1971) provided a list of characteristics to differentiate Panocalda from the closely related Panops and Neopanops. Both Schlinger (1959) and Neboiss (1971) distinguished their respective genera based on characters such as eye pilosity, length of proboscis, shape of ocellar tubercle, palpi length, head width, parafacial pilosity and wing length. With the inclusion of the four new species described here, and a critical re-examination of the characters used to differentiate Neopanops and Panocalda from Panops, it is clear that all of these characters are variable and that only one genus is warranted. Some species of Panops have pilose eyes, either uniformly sparse and minute (i.e. P. danielsi sp. n., P. boharti comb. n., P. baudini) or localized (P. grossi comb. n.), with the other species being apilose. In no species of Panops are the eyes uniformly dense pilose, as is found in most other panopine genera (e.g. Apsona, Lasia). This paucity of eye pilosity is shared with only a few other genera, including the Australian Leucopsina and Mesophysa, as well as the highly derived genus Corononcodes Speiser, 1920 from the Palaearctic and Afrotropical regions. Proboscis length is a frequently used character in acrocerid taxonomy, but in Panops the length is dramatically variable, with a proboscis much shorter than the head height in some species (e.g. P. jade sp. n., P. schlingeri sp. n., P. boharti comb. n.) while the rest have a proboscis longer than the head height. Panops is a variable genus, but can be differentiated from all other Panopinae based on the diagnosis above, and specifically from all other genera in the Australasian region based on tibial spines being present (cf. Apsona) and wing crossvein 2r-m joining to R 4+5 (cf. Leucopsina, Mesophysa). Like most acrocerids, species of Panops display distinct sexual dimorphism with males often have slightly smaller body size and larger antennae than females. Many Old World panopine genera (e.g. Apsona, Panops, Rhysogaster Aldrich, 1927) have a distinctive unidirectional arrangement of the pile on the head and thorax, giving the individual a dramatic change in appearance when viewed head on (e.g. Figs 20, 23, 40); the biological significance of this is unknown.

Key to Panops species
Panops baudini keys to two couplets as the eye pilosity is extremely minute in some individuals and may be overlooked. Females are unknown for P. boharti comb. n. and P. aurum sp. n., whilst males are unknown for P. schlingeri sp. n.
Etymology. The specific epithet is derived from the Latin, aurum -gold; referring to the distinctive golden setal pile on the head and thorax.
Comments. Panops aurum sp. n. is known only from a single male specimen from Western Australia. The fringing yellow setae around the oral cavity and yellow pile on the thorax are distinctive for the species. pubescence; clypeus length equal to oral cavity, brown-black; palpus white or black; margin of oral cavity (parafacial) glabrous; proboscis equal or slightly longer than head height; flagellum dark yellow-orange, suffused with brown, apex in male tapered, narrow apically; scape and pedicel brown or dark yellow. Thorax postpronotal lobe green; scutum metallic green or metallic blue, scutal vestiture dense white pile; scutellum metallic blue-green; pleuron metallic green or metallic blue; coxae black with metallic blue iridescence; femora black; tibiae black or brown; tarsi black; lower calypter white, with brown margin; wing hyaline (male) or slightly infuscate (female), venation dark; vein R 4 with spur vein. Abdomen shape rounded globose, much larger than thorax (female) or rounded to conical, not larger than thorax (male), colour metallic green or metallic blue violet, vestiture as minute setae, dense white-silver elongate setae along anterior margin of tergites 2-5.
Redescription. Body length: 9.5-12.5 mm (male), 11.0-14.0 mm (female). Head with eye sparsely pilose with minute setae (appears apilose); ocellar tubercle raised laterally or relatively flat; medial ocellus reduced; occiput brown-black, occipital pile white, sparse; postocular ridge and gena overlain with grey pubescence; clypeus length equal to oral cavity, brown-black; palpus white or yellow; margin of oral cavity (parafacial) pilose; proboscis longer than head height; flagellum redbrown to black; scape and pedicel brown. Thorax with postpronotal lobe brownblack; scutum black, scutal vestiture dense white pile; scutellum black; pleuron black (thorax with slight bluish iridescence in western populations); coxae black; femora black or brown-black, apices dark yellow; tibiae predominantly black with dark yellow to white (apically); tarsi dark yellow to white; lower calypter white, with yellow margin; wing hyaline (male) or slightly infuscate (female); venation dark; vein R 4 with spur vein, rarely without. Abdomen shape rounded globose, much larger than thorax, colour highly variable, orange-red to yellow, dark markings anteriorly and medially, or dark yellow, brown anteriorly on tergites 2-6, vestiture as extensive short white-silver pile, longer laterally. Comments. The type for the genus, Panops baudini is the most commonly represented species in collections. This species is distributed in Queensland, New South Wales, Victoria and Western Australia. The apex of the aedeagus is broad and quadrangular in this species (Fig. 17) while in all other species it is much narrower. The record from Tasmania is apparently erroneous (Neboiss 1971). Western Australian individuals have more reddish colouration laterally on the abdomen, particularly in males, and the body has a bluish iridescence (Fig. 1). This bluish iridescence is not seen in specimens from eastern states. (Schlinger, 1959)  yellow; parafacial without marginal pile; postpronotal lobe cream with brown spot; legs yellow, femora brown with yellow apices; lower calypter cream with brown margin.
Comments. Panops boharti comb. n. was described by Schlinger (1959) as the sole species in the genus Neopanops but is transferred herein to Panops. This Indonesian species is the only non-Australian representative of the genus, and is distinctive based on body colouration and markings, very short mouthparts, eye pilosity and eye shape. Only the male is known.   Panops conspicuus (Brunetti, 1926) http://species-id.net/wiki/Panops_conspicuus Figs 34-38 Epicerina conspicua Brunetti, 1926: 579. Panops conspicuus (Brunetti, 1926) -Edwards 1930Paramonov 1957  Diagnosis. Eye apilose; proboscis longer than head height; body colour and shape sexually dimorphic: male black with slender body, female yellow and brown with globose abdomen; antennae yellow-brown to red-brown with black suffusion; parafacial without marginal pile; postpronotal lobe yellow; legs yellow with brown medially on femora and tibiae.

Panops danielsi
Diagnosis. Eye uniformly sparse pilose; proboscis longer than head height; body dark yellow and brown, with metallic green-blue iridescence; antennae red-brown or black; parafacial with marginal pile; postpronotal lobe dark yellow; legs dark yellow and brown.
Etymology. This species is named in honour of the collector of this species, Greg Daniels.
'Allotype'. AUSTRALIA: Northern Territory: same data as holotype (SAM). Diagnosis. Eye pilose dorsally only, relatively dense and elongate; proboscis shorter than head height; body colour and shape sexually dimorphic: male metallic olive green, female yellow and brown, globose; antennae yellow; parafacial without marginal pile; postpronotal lobe and legs concolourous with rest of body.
Redescription. Body length: 9.0 mm (male), 12.0 mm (female). Head eye pilose dorsally only, dense and relatively elongate; occiput olive green, occipital pile dense white (male) or yellow (female); postocular ridge and gena overlain with grey pubescence; ocellar tubercle raised laterally or relatively flat; medial ocellus absent; clypeus shorter than oral cavity, yellow-brown; palpus black; margin of oral cavity (parafacial) glabrous; proboscis not extending beyond oral cavity; flagellum yellow, apex in male uniform width, truncated apically; scape and pedicel brown. Thorax with postpronotal lobe yellow (female) or green (male); scutum metallic olive green or yellow-orange; scutal vestiture dense white or yellow-gold pile; scutellum metallic olive green or orange-yellow with brown suffusion; pleuron orange or metallic olive green; coxae brown; femora brown-black, apices dark yellow; tibiae brown; tarsi brown; lower calypter white, brown marginally on membrane or white, with dark yellow margin; wing hyaline or slightly infuscate, venation dark; vein R 4 without spur vein. Abdomen shape with male rounded, not larger than thorax, metallic olive green, vestiture dense short pile, longer laterally; female rounded globose, much larger than thorax (female), orange-yellow (female), vestiture elongate yellow pile.
Comments. Panops grossi comb. n. was described by Neboiss (1971) as the sole species in the genus Panocalda but is transferred herein to Panops. This species is apparently closely related to P. boharti comb. n. based on eye pilosity, and P. schlingeri sp. n. and P. jade sp. n. based on the short mouthparts. All of these species are northern Australian or Indonesian species. Panops grossi comb. n. can be distinguished from all other Panops based on the dense patch of relatively elongate pile on the dorsal part of the eye. This species displays a dramatic sexual dimorphism similar to that found in P. conspicuus, with females being orange-yellow in colour.   Diagnosis. Eye apilose; proboscis shorter than head height; body metallic greenblue to violet iridescence; antennae red-brown; parafacial with marginal pile; postpronotal lobe concolourous with rest of thorax; legs black with metallic blue-violet iridescence. Description. Body length: 11.5 mm (male), 11.5-12.0 mm (female). Head with eye apilose; ocellar tubercle relatively flat; medial ocellus present; occiput metallic green-blue, occipital pile white, sparse; postocular ridge and gena overlain with grey pubescence; clypeus length equal to oral cavity, black with blue-green suffusion; palpus black; margin of oral cavity (parafacial) pilose; proboscis extending beyond oral cavity, but shorter than head height; flagellum apex in male tapered, slightly rounded apically, red-brown; scape and pedicel red-brown. Thorax with postpronotal lobe blue-violet; scutum metallic blue-violet, green posteromedially; scutellum metallic blue-violet; coxae and femora with metallic blue-violet iridescence; tibiae black; tarsi black; lower calypter white with brown margin; wing hyaline, venation dark; vein R 4 with spur vein. Abdomen shape rounded globose, much larger than thorax, colour metallic green or blue-violet iridescent, vestiture extensive white-silver short pile, longer laterally.

Panops jade
Etymology. This beautifully coloured species is named after my daughter, Jade Tanya Winterton, whose name also describes the deep green colouration found in this species.
Comments. Panops jade sp. n. is a distinctive species with extensive green to blueviolet iridescence, particularly in the female. It is similar to the western Australian species, P. austrae, but is distinguished by the length of the mouthparts, leg colour and different vestiture pattern on the abdomen. Panops jade sp. n. is known only from Isla Gorge National Park in southern Queensland. Both males and females are recorded from Spinifex grass (Triodia sp.), presumably at rest.    Diagnosis. Eye apilose; proboscis shorter than head height; body metallic greenblue iridescence; antennae orange; parafacial without marginal pile; postpronotal lobe dark yellow; legs dark yellow, femora brown-black with yellow apices.
Description. Body length: 9.5-11.0 mm (female only). Head with eye apilose; ocellar tubercle relatively flat; medial ocellus present; occiput metallic green-blue, occipital pile white, dense; postocular ridge and gena overlain with grey pubescence; clypeus shorter than oral cavity, brown-black; palpus black; margin of oral cavity (parafacial) glabrous; proboscis not extending beyond oral cavity; flagellum orange; scape and pedicel dark red-yellow. Thorax with postpronotal lobe yellow; scutum metallic green to blue iridescent; scutal vestiture dense white pile; scutellum metallic blue-green; pleuron metallic green to blue iridescent; coxae brown-black with metal-  lic blue iridescence; femora brown-black, apices dark yellow; tibiae dark yellow; tarsi dark yellow; lower calypter white, with dark yellow margin; wing hyaline, venation dark; vein R 4 without spur vein. Abdomen shape rounded globose, much larger than thorax, dark with metallic green to blue iridescence, vestiture as dense short pile, longer laterally.
Etymology. I am honoured to name this species after the world-renowned Acroceridae taxonomist Dr. Evert Irving Schlinger.
Comments. Panops schlingeri sp. n. is known only from two female specimens collected in the Northern Territory. This species is differentiated easily by the green-blue iridescence on the body and dark yellow postpronotal lobes.

Subfamily Philopotinae Schiner, 1968
http://species-id.net/wiki/Philopotinae Type genus. Philopota Wiedemann. Schlinger, 1971: 186. Diagnosis. Body shape slightly to strongly arched and never densely pilose; small to medium sized; antennal flagellum stylate; postpronotal lobes enlarged and meeting medially to form collar behind head; tibial spines absent; wing costal vein ending at wing apex, never circumambient; wing venation highly variable, ranging from relatively complete with cells cu-p, bm br, d and basal r 4+5 present, to highly reduced with only cell br present; cell m 3 absent; veins R 4 and R 5 always present as single vein R 4+5 ; cubital and medial veins not reaching posterior wing margin; larvae exclusively parasitoids of araneomorph spiders.
Helle can be differentiated from all other philopotine genera based on the relatively complete wing venation, inflated R 1 at pterostigma, palpi present and apilose eyes.     . Body shape arched; body colouration non-metallic dark brown; head width much smaller than thorax (female) or slightly smaller than thorax (male); head spherical; postocular ridge and occiput extended posteriorly into slight ridge; posterior margin of eye rounded; eyes bare; position of antennae on head near middle of frons, slightly nearer to mouthparts; eyes contiguous above antennal base, not contiguous below; palpus present; proboscis longer than head; antennal flagellum stylate, apex with terminal seta; thorax with postpronotal lobes enlarged, medially contiguous to form collar; subscutellum  enlarged; legs not greatly elongated; pulvilli present; wing hyaline, markings absent; costa ending in radial field; costal margin straight in both sexes; humeral crossvein absent; radial veins meeting wing margin before wing apex; R 1 inflated distally at pterostigma; R 2+3 present; R 4+5 slightly curved anteriorly midway; veins M 1 , M 2 and M 3 present; discal cell absent; medial veins reaching wing margin (or nearly so); crossvein 2r-m absent; Cu reduced, not reaching wing margin; anal lobe not enlarged; alula well developed; abdomen smooth, rounded, cylindrical in shape, similar width to thorax (male) or greatly rounded, inflated (female).  Gillung & Winterton, 2011. Comments. Schlingeriella is differentiated from other Philopotinae by medial veins mostly reaching the wing margin, R 1 inflated apically, reduced wing venation (i.e. absence of all wing cells except cell br), elongate mouthparts and apilose eyes. See results of Winterton et al. (2007) for phylogenetic placement and divergence times. This genus is represented by only a single species (S. irwini sp. n.) from New Caledonia (France). There is dramatic sexual dimorphism in body size, with females considerably larger than the males. This genus was described by Gillung and Winterton (2011) to honour the decades of work by Evert I. Schlinger on world Acroceridae taxonomy. Evert Schlinger not only collected many of the specimens in New Caledonia, he also recognized that it represented a completely new genus of endemic spider flies. Diagnosis. Small to medium sized, densely pilose to apilose, body rarely arched; antennal flagellum stylate; postpronotal lobes widely separated, never medially contiguous; wing venation highly variable, ranging from complete with cells cu-p, bm br, d, m 3 and basal r 4+5 present, to highly reduced with few closed cells; humeral crossvein rarely well developed; tibial apical spines absent (rarely present); larvae exclusively parasitoids of araneomorph spiders.   thorax width, shape sub-spherical; postocular ridge and occiput rounded; two or three ocelli, anterior ocellus sometimes absent; posterior margin of eye rounded; eye apilose; position of antennae on head adjacent to mouthparts; eyes contiguous above antennal base, not contiguous below antennal base; palpus absent; proboscis apparently absent; flagellum shape stylate; apex with terminal setae (or single seta); antenotum not collarlike behind head; subscutellum enlarged; tibial spines absent; pulvilli present; wing hyaline, markings absent; costa ending near wing apex, costal margin straight; humeral crossvein absent; radial veins straight; R 1 inflated or not inflated distally; pterostigma and cell r 1 membranous, not ribbed; only two radial veins present, R 2+3 absent, R 4+5 not reaching wing margin; medial vein compliment with M 1 , M 2 and M 3 present, or two M veins present; discal cell weakly formed or absent; medial veins not reaching wing margin; cell m 3 absent; CuA 1 absent; CuA 2 separate from A 1 , ending just before wing margin; crossvein 2r-m absent; wing microtrichia absent; anal lobe well developed; alula well developed; abdominal tergites smooth, rounded (rarely with tubercles in fossil species); abdomen shape greatly rounded, inflated.

Included species. Schlingeriella irwini
Included species. Ogcodes is a distinctive and cosmopolitan genus and the most species-rich in the family. Thirty-four species in two subgenera (Ogcodes and Protogcodes Schlinger, 1960) are listed by Schlinger and Jefferies (1989) for the Australasian region.

Comments.
Ogcodes is in need of revision and no recent keys to species have been published for the region. The most recent revision of the genus was by Schlinger (1960), but there are many undescribed species in collections and a world revision of the genus is needed. Ogcodes is a derived genus with a typical globose body, relatively small head and reduced wing venation. Characters which differentiate Ogcodes from all other Acroceridae genera include antennae proximal to mouthparts, palpi absent, proboscis very short, almost all wing cells absent or poorly formed, eyes apilose and R 2+3 absent. . Body shape not arched. Body colouration non-metallic; head much narrower than thorax width; shape nearly spherical; postocular ridge and occiput rounded; three ocelli; posterior margin of eye rounded; eye pilose (dense); antennae located adjacent to mouthparts; eyes contiguous above antennal base, not contiguous below antennal base; palpus absent; proboscis greatly reduced; flagellum stylate, apex with terminal setae (multiple); antenotum shape not collar-like behind head; subscutellum not enlarged, barely visible; tibial spines present; pulvilli present; wing markings absent; costa circumambient; wing costal margin straight or with anterior projection (males); humeral crossvein present or reduced; radial veins curved or angled towards wing anterior margin; R 1 inflated distally at pterostigma (especially in male); pterostigma and cell r 1 membranous, not ribbed; R 2+3 present; R 4+5 present as single vein; basal cell r 4+5 (portion basal to bisecting 2r-m) merged with discal cell to form composite cell comprising d+r 4+5 ; cell m 3 absent; medial vein compliment usually a single M vein fused with CuA 1 , petiolate to margin, sometimes with second medial vein originating from cell d+r 4+5 ; CuA 2 fused to A 1 before wing margin, petiolate, rarely open to wing margin; wing microtrichia absent; anal lobe well developed; alula present or absent, rarely well developed; abdominal tergites smooth, rounded; abdomen shape greatly rounded, inflated.

Comments.
Pterodontia is a cosmopolitan genus containing 19 valid species, three of which are recorded from the Australasian region (Schlinger and Jefferies 1989). Pterodontia variegata was described by White (1914) and differentiated from P. melli (as P. macquarti Westwood, 1848) based on colouration of the fore femur, scutellum and abdomen. Paramonov (1957) examined a range of specimens from various localities and suggested that the former was likely a synonym of the latter. Based on examinations of these and additional specimens this synonymy is supported herein.
Some species of Pterodontia have greatly enlarged and sclerotized lower calypters, appearing somewhat like a second pair of wings (e.g. P. davisi). Males in this genus typically have sclerotized projections on the costal margin of the wing. Characteristics which diagnose this genus from other acrocerids include head very small relative to thorax width, tibial spines present, cells m 3 , d and basal r 4+5 fused to form a single cell, eyes densely pilose, antennae adjacent to the ocellar tubercle and mouthparts reduced. Contrary to other authors, Pterodontia has been placed previously in Panopinae by Schlinger (1981Schlinger ( , 1987Schlinger ( , 1989) based on the presence of tibial spines. The wing venation of Pterodontia is unique among acrocerids.