Review of Australian Sarginae Soldier Fly Genera (Diptera: Stratiomyidae), with First Records of Cephalochrysa , Formosargus and Microchrysa

. A taxonomic treatment to genera is provided for the Australian members of the soldier fly subfamily Sarginae. This includes an updated identification key for the Australian genera, along with the diagnosis and illustration of Ptecticus Loew, 1855 and Sargus Fabricius, 1798, and three newly recorded genera: Cephalochrysa Kertész, 1912 ( Cephalochrysa gselli (Hill, 1919) comb. nov.), Formosargus James, 1939 and Microchrysa Loew, 1855. Two new species are also described: Formosargus melanogrammus Lessard & Woodley, sp. nov. and Microchrysa wrightae Lessard & Woodley, sp. nov. A new Australian record is presented for Ptecticus longipes (Walker, 1861), also known from New Guinea and the Solomon Islands, and a taxonomic change is made for Formosargus lineata (de Meijere, 1913) comb. nov., from New Guinea, transferred from its previous position within Chrysochlora Latreille, 1829. Five genera and 10 species of Sarginae are now recognized from Australia.


Introduction
The Sarginae are a moderate-sized subfamily of soldier flies, with more than 530 species described in 23 genera, distributed on every continent, excluding Antarctica (Woodley, 2001). Prior to this study, the Australian Sarginae comprised only two cosmopolitan genera, Ptecticus Loew, 1855and Sargus Fabricius, 1798(Woodley, 2001. Little is known regarding the biology of the Australian fauna, although sargines from overseas are usually associated with vegetation and have an underappreciated role in decomposition. Adults swarm during mating and can be found on vegetation and flowers (Rozkošný, 1982;Woodley, 2001). Females are usually located near larval food sources and oviposit in decaying fruits, bases of palm leaves and freshly cut logs, whereas males frequent these sites in search of mates (Woodley, 2001). Larvae are often associated with decaying organic matter, including grass, compost heaps (Woodley, 2001) and animal faeces (Rozkošný, 1982). Woodley (2001) defined the Sarginae as usually slender flies with the antennal flagellum formed of five flagellomeres, with the first four reduced, compact and rounded to form a basal complex, and the apical flagellomere being aristate, and wings with crossvein m-cu connected to vein M 4 by presence of dM 3+4 (previously bm-cu; see Lessard et al., 2019). He noted that African and Madagascan flies vary by having additional flagellomeres and by lacking wing vein dM 3+4 (i.e., Gongrosargus Lindner, 1959;Hauser et al., 2017: 41, fig. 182), leading him to call for a worldwide generic revision. In his phylogenetic hypothesis based on morphology (Woodley, 2001: 17, fig. 1), the Sarginae recovered as sister to the Chrysochlorininae, forming a well-supported monophyletic clade with the Hermetiinae, supported by the morphological characters of the concave posterior surface of the head, elongation of the antepronotum and unarmed scutellum.
The Sarginae appears to be monophyletic in the only molecular study on soldier fly phylogeny, one based on two genes (Brammer & von Dohlen, 2007: fig. 3). In this study, the Hermetiinae, Chrysochlorininae and Sarginae formed a strongly supported monophyletic clade, with the addition of the Nemotelinae which recovered as sister to the Sarginae. In the subsequent morphological analysis of Brammer & von Dohlen (2010: fig. 3), the Sarginae were not monophyletic, instead forming a series of successive clades sister to a larger clade containing Hermetiinae + Clitellariinae (paraphyletic clade 2) + Chrysochlorininae. In the last two studies, only four of the 23 genera of Sarginae were sampled and did not include members from Australia, therefore, the phylogenetic relationships remain unclear for the Australian Sarginae.
The taxonomy of the Australian soldier flies has received little attention and the number of taxonomic treatments for the Sarginae are limited. For the genus Sargus, only a handful of publications have each described a single species without providing a clear generic diagnosis (White, 1916;Hill, 1919;Hardy, 1932). The largest revision of Australia sargines was conducted by  on Ptecticus from Australia, New Guinea and the Bismarck and Solomon Islands, with the description of three species from Australia, however, these were later synonymized by Rozkošný & de Jong (2003: 243). Therefore, there is a strong need for a generic revision of the Australian genera. This paper is part of a recent surge of renewed taxonomic interest revising the genera of the Australian soldier flies (Lessard et al., 2018(Lessard et al., , 2019(Lessard et al., , 2020. A taxonomic treatment for the Australian sargines is provided to clarify the generic limits and identification of the regional fauna. An updated key to Australian sargine genera is presented, along with the diagnosis and illustration of the Australian fauna of Ptecticus and Sargus, and the first Australian records of the newly recorded genera Cephalochrysa Kertész, 1912(Cephalochrysa gselli (Hill, 1919 comb. nov.), Formosargus James, 1939 (also Oriental) and Microchrysa Loew, 1855 (cosmopolitan). Two new species are described: Formosargus melanogrammus Lessard & Woodley, sp. nov. and Microchrysa wrightae Lessard & Woodley, sp. nov. A new Australian record is presented for Ptecticus longipes (Walker, 1861), also known from New Guinea and the Solomon Islands, and a taxonomic change is made for Formosargus lineata (de Meijere, 1913) comb. nov., from New Guinea, transferred from its previous position within Chrysochlora Latreille, 1829. Five genera and 10 species of Sarginae are now recognized from Australia.

Materials and methods
Specimens were examined using a Zeiss dissecting microscope. Photographs were taken on a Dun Inc. BK Imaging-PLUS Lab System using a Canon 65 mm lens, stacked in Zerene Stacker v. 1.0 software and processed in Adobe Photoshop CS6 to obtain a fully-sharpened image.
Morphological terminology follows Hauser et al. (2017), with updated wing venation terminology following Lessard et al. (2019) (Fig. 1). Frontal index was calculated by dividing  (Walker, 1858) , anterior branch of radius; r 1 , first radial cell; R 2+3 , fused second and third radial branch; r 2+3 , second + third radial cell; R 4 , upper third radial branch; r 4 , fourth radial cell; R 5 , lower third radial branch; r 5 , fifth radial cell; Rs, radial sector; r-m, radial-medial crossvein; Sc, subcostal vein; sc, subcostal cell. the width at the middle of the frons by the distance from the anterior ocellus to the base of antennae (Mason & Rozkošný, 2008). Body lengths are given exclusive of antennae.
Genitalia were prepared by dissecting and incubating the apical portion of the abdomen in KOH at 100°C overnight, followed by a wash in distilled water. After examination in glycerine, the genitalia were transferred to KY jelly and imaged on a Leica M205A microscope and stacked using Helicon Focus 5.3 software. Genitalia were then transferred into glycerine and stored in microvials pinned below each specimen.
Holotype specimen labels are quoted verbatim ("") and individual lines are separated by forward slashes ( / ). Type specimens were imaged for all genera, excluding P. longipes (represented by non-type specimens), and Ptecticus rogans (Walker, 1858) (represented by the holotype male and paratype female of the previously synonymized species Ptecticus queenslandicus syn. Rozkošný & de Jong, 2003), where type specimens were unavailable for photography. The subfamily and generic diagnoses are given for the Australian fauna only. Collection localities for all species, including novel primary type localities (labelled), are presented in Fig. 2.
The following abbreviations are used in the text: HT, holotype; LT, lectotype; PT, paratype; NP, Australian national park; the Australian states New South Wales, Northern Territory and Queensland are NSW, NT and Qld. Geospatial coordinates of certain labels should be read as degrees and minutes not degrees to two decimal places e.g., "15.03S 145.09E" on D. H. Colless labels = 15°03'S 145°09'E. Updates are proposed for insertion into Woodley's (2001)

Subfamily Sarginae
Diagnosis. Small to large flies (length 5-16 mm), usually slender, dull yellowish brown or metallic purplish or greenish blue (Figs 3-14). Head large, wider than thorax, separated from thorax by the well-developed, anteriorly produced antepronotum; occiput strongly concave; eyes usually superficially appearing as bare, with short, relatively sparse hair-like setae visible under higher magnification, occasionally dense, holoptic or narrowly dichoptic in males, dichoptic in females, ommatidia slightly wider anteriorly, with or without distinct demarcation of change in dorsoventral size; ocellar triangle prominent. Males with upper frons narrow, triangular; lower frons diverging or converging ventrally at margins, occasionally bulbous and anteriorly produced; females with narrow to wide frons (index 1.4-4.8), margins parallel-sided or converging ventrally. Face narrow to wide, rounded and not visible in profile, or with a small, anteroventrally produced, beak-like protuberance that is narrowly visible in profile, usually with a well-defined horizontal impression separating face from ventrally receding oral margins, with two distinct, tentorial pits visible at lateral margins below horizontal impression. Antennae inserted below middle of head, short (equal to length of head) or long (exceeding length of head), scape cylindrical and apically expanded, pedicel sometimes expanded apically on inner surface, flagellum with five flagellomeres, first four flagellomeres compact, rounded and laterally compressed to form an ovoid basal complex, apical margin usually with short, dense, hair-like setae, apical flagellomere aristate, arising anterodorsally from basal complex, usually with two prominent, moderately long, basal hair-like setae. Palpi short, two-segmented, second segment ovoid, often obscured within oral cavity. Proboscis short, labella fleshy. Scutum elongate and slender, about 1.1-1.2 times as long as wide, cuticular surface convex, shining, yellowish brown or strongly metallic bluish purple or greenish, hair-like setae usually dense; scutellum slightly raised or in same plane as scutum, short, about 0.4-0.5 times as long as wide, rounded to almost triangular, posteromedially pointed, unarmed, with hair-like setae; mediotergite well-developed, rounded, subshining, visible in both dorsal and lateral views, usually with some hair-like setae. Legs slender, without significant modification. Wings usually hyaline, occasionally infuscated with brown, set with microtrichia; R 2+3 arising proximal or distal to r-m; R 4 always present; four medial veins strong or faint, terminating before or reaching margin, and issued from discal cell, m-cu usually connected to M 4 and separated from discal cell by dM 3+4 , occasionally connected to discal cell; post-tegula present, with small dorsal tuft of hair-like setae; lower calypter with or without small membranous strap-like lobe at base of wings. Abdomen yellowish brown or metallic bluish purple or green, ovoid (about 1.2-1.4 times as long as wide) or elongate and slender (about 2-3 times as long as wide), with 5 large, well-defined tergites, usually with dense hair-like setae. Females with two segmented cerci.
Remarks. Closely related to the Hermetiinae and Chrysochlorininae, sharing the posterior surface of the head being concave, elongation of the antepronotum, and unarmed scutellum, but distinguished by the combination of the following characters: antennae with five flagellomeres, the apical flagellomere being aristate; wings with M 4 issued separately from discal cell by having m-cu connected to M 4 .
Australian distribution of Sarginae. New South Wales, northern NT and Queensland (Fig. 2). Frons wide and almost parallel in females; face slightly anteroventrally produced to form a small beak-like protuberance visible in profile view; scutum with a distinct black medial vitta; wings with vein M weak and nearly unpigmented between cells br and bm, M 1 and M 3 very weakly developed, M 4 connected to discal cell (i.e. dM 3+4 absent); alula reduced, almost linear ( Fig. 4)  Distribution. Bathurst Island, NT, new distribution (Fig. 2).

Remarks. Sargus gselli Hill, 1919 is congeneric with
Cephalochrysa, sharing the following: head being much wider than high, ocelli forming an equilateral triangle and occiput without a posteriorly projecting fringe of hair-like setae. The general appearance of S. gselli is extremely similar to other species of Cephalochrysa known from Pacific islands, as well as the type species. Therefore, we transfer this species from its previous position in Sargus to become Cephalochrysa gselli (Hill, 1919) comb. nov., the first record of Cephalochrysa from Australia.

Catalogue of Australian species
Genus Cephalochrysa Kertész, 1912 gselli (Hill, 1919)  Diagnosis. Small (length 5-7 mm), yellowish brown species, similar to Ptecticus, but distinguished by the: frons wide and almost parallel in females; face slightly anteroventrally produced to form a small beak-like protuberance that is visible in profile; scutum with a distinct black medial stripe; wings with vein M 1 and M 3 extremely weak and nearly unpigmented between cells br and bm; M 1 and M 3 very weakly developed; M 4 issued from discal cell (i.e. dM 3+4 absent); alula reduced, almost linear; and lower calypter linear, without projecting process.

Remarks.
Regarding the New Guinean fauna, Chrysochlora lineata de Meijere, 1913, is congeneric with Formosargus, sharing the characters noted above in the diagnosis. Therefore, we propose moving the species into the latter genus, to become Formosargus lineata (de Meijere, 1913) new combination.
Distribution. Northern Queensland, new distribution record (Fig. 2).    tubercle black, ocelli in the form of an equilateral triangle, hair-like setae moderately long and dense, golden yellow. Occiput not visible in lateral view, occipital plate covered in moderately long, dense, golden yellow hair-like setae. Face with cuticular surface shining, with some sparse, moderately long, hair-like setae at lower margins, oral margin with dense, relatively short, golden yellow hair-like setae.

Formosargus melanogrammus
Antennae long, scape+pedicel+flagellum about 1.6 times as long as head, pedicel about 0.4 times as long as scape at outer surface, apically expanded and evenly rounded on inner surface, both segments pale yellow, with short, golden brown hair-like setae; flagellum about 1.8 times as long as scape+pedicel, basal complex yellow, apical margin covered with short, relatively dense, yellowish hair-like setae, apical flagellomere long, about 3 times as long as scape+pedicel.
Thorax. Scutum pale yellowish brown, with a distinct dark brownish black medial line, hair-like setae moderately long, dense, erect, golden yellow, becoming darker brown dorsomedially; scutellum in same plane as scutum, dark brownish black on more than medial third, pale yellowish brown at lateral margins, hair-like setae moderately long, brown, more yellowish at margins; mediotergite same colour as scutum, with relatively long, erect, golden hair-like setae; pleura pale yellow, shining, hair-like setae relatively long, sparse, golden yellow. Legs pale yellow with yellowish hair-like setae. Wings hyaline; discal cell elongate, about 1.5 times as long as wide; all four medial veins issued from discal cell, terminating just before margin; CuA curved; alula about 6 times as long as wide, surface bare of microtrichia, marginal hair-like setae about equal to width of alula; posttegula with small dorsal tuft of dense, orangey yellow hair-like setae.

Abdomen.
Elongate ovoid, about 1.2 times as long as wide, widest at tergite 4, yellowish brown, with darker brown infuscation becoming more prominent from tergites 3 onwards, hair-like setae relative long, dense, appressed golden yellow, becoming longer and more erect at lateral margins. Sternites pale yellowish brown, hair-like setae relatively long, appressed, golden yellow. Terminalia cuticular surface and hair-like setae yellowish brown, cerci with both segments about equal in length, second segment parallel-sided and tapering apically.
Etymology. This specific name is derived from the Greek, melan, black, and gramme, line, referring to the distinctive black medial stripe on the scutum.
Remarks. The face is slightly anteroventrally produced to form a beak-like protuberance, similar to Hermetia Latreille, 1804, but not as distinct.
This species is very similar to F. lineata (New Guinea), differing mainly in the form of the thoracic vitta. Unfortunately, the wings in the holotype female of F. lineata are mostly destroyed, so comparisons of wing characters cannot be made. Also, only females are known for both species so male terminalia characters are also unavailable.
One additional specimen from the Mt Lamond track (♀, "beginning of Mt Lamond track / Iron Range Nat. Park, Qld / 12°43'34"S 143°17'06"E / 3 Jan 1996 20 m / G. and A. Daniels" AMS K.478680) most likely represents an undescribed species as it is larger in size (length 7 mm), and has an incomplete thoracic vitta that is mostly absent anterior to the transverse suture, and abdomen with more defined, almost black markings predominantly on tergites 2 and 3.  (Woodley, 2001(Woodley, , 2009

Diagnosis.
A small (length 5.0-5.5 mm) species, with metallic golden or purplish green thorax, pale yellow legs with a dark brown marking on the apical half of the hind tibiae, and antennae and palpi yellow in males, darker brown in females. This species can be distinguished from M. flaviventris by the abdomen without green colouration in males (tergite 5 with green colouration in M. flaviventris), and both sexes  Description. Male. Length 5.0-5.5 mm. Head. Eyes holoptic, contiguous about one-third the length of frons from vertex, with distinct demarcation of change in size of ommatidia just above antennae. Upper frons blackish, bare, lower frons diverging ventrally at margins, with a distinct linear impression, cuticular surface subshining, upper half pale brown, lower half black, hair-like setae relatively short, dense, golden; ocellar tubercle relatively bulging at each ocellus, ocelli almost in the shape of an equilateral triangle, slightly elongated anteriorly, black with reflections of green, hair-like setae relatively short, yellowish. Occiput not visible in lateral view, occipital plate relatively bare, with short, yellowish hair-like setae limited to lateral margins. Face wide, narrowly visible in profile, shining metallic green and gold, hair-like setae relatively short, dense, golden yellow. Antennae relatively s, scape+pedicel+flagellum about equal to length of head, scape about equal to length of pedicel, pedicel slightly expanded and curved gently apically on inner surface, both segments pale yellow, flagellum basal complex yellow, with small, irregular, circular presumably sensory pits, apical margin with short, golden hair-like setae, apical flagellomere yellowish brown, about 1.7 times as long as scape+pedicel. Palpi very short, yellow, with short, yellowish hair-like setae. Proboscis yellowish, with short, yellowish hair-like setae.
Thorax. Scutum shining metallic golden green, occasionally with purplish reflections, with relatively short, dense, appressed, golden hair-like setae; scutellum slightly raised relative to scutum, same colour as scutum, with relatively short, dense, golden hair-like setae; mediotergite same colour as scutum, with a few moderately long, golden hair-like setae; pleura brownish with reflections of green to gold, with a prominent, narrow, whitish horizontal strip encompassing postpronotal lobe and upper margin of anepisternum, hair-like setae pale yellow to whitish. Legs with pale yellow coxae, femora, tibiae and tarsi, brown on apical half of hind tibiae, hair-like setae pale yellowish on all segments. Wings hyaline; cell r 1 stained entirely pale yellow; R 2+3 arising distal to r-m, exceeding length of discal cell; discal cell small, slightly elongate, about 1.3 times as long as wide; all medial veins terminating before reaching margin, M 1 and M 3 the weakest, both occasionally reduced to appendices or appearing as absent, M 4 issued separately from discal cell by dM 3+4 ; CuA relatively straight, curving at extreme end toward margin, petiole vein CuA+CuP short; alula large, slightly expanded and relatively pointed apically, surface without microtrichia; post-tegula yellowish, with yellowish hair-like setae; lower calypter with small straplike lobe present, hair-like setae dense, relatively long, pale golden yellow.
Female. Length 5.0-5.5 mm. Similar to males, but slightly more bluish purple in colouration on the thorax and the abdomen, abdomen is concolorous with the scutum. Eyes with ommatidia of uniform size, with extremely sparse, short, whitish hair-like setae. Frons wide (index 1.4-1.5), with a strong medial impression, margins converging ventrally, shining metallic purplish to aqua blue, with relatively sparse, short, dull yellowish white setae, lower frons with a pale yellowish brown horizontal band. Occiput well developed, shining metallic purplish to aqua blue, dorsal half visible in lateral view. Antennae darker yellowish brown. Palpi dark brown. Abdomen with tergites blackish with strong reflections of green to purplish blue, concolorous with thorax, lateral hair-like setae whitish; sternites dark brown to black, with subtle bluish reflections, hair-like setae whitish.
Etymology. This specific name is in honour of Susan Wright, Collection Manager of Entomology, QM, for assistance and access to the collection.  Brisbane, Although little is known regarding the biology of the Australian sargine fauna, this genus appears to be associated with vegetation, based on collection labels of specimens belonging to three undescribed species: two specimens from Brisbane (AMS K.453231, K.453232) were collected from leaves of Physallis peruviana (Solanaceae); a series of females from Carnarvon Golf Club, NSW (AMS K.478683-K.478691) were collected from a woodchip pile, and; a female from Snake Bay (presumably NT; ANIC 29-059096) and male from Melville Island (NT, ANIC 29-059101) were collected from the native shrub Opilia amentacea (Opiliaceae). Distribution. Northern Queensland (Fig. 2).

Genus Ptecticus Loew, 1855
Remarks. Rozkošný & de Jong (2003) synonymized the species proposed by : Ptecticus albitarsus : 574 (= quadrifasciatus Walker, 1860, Ptecticus amplior : 581 (= complens Walker, 1858 and P. queenslandicus (= rogans Walker, 1858;Daniels, 1979: 580). Here we present the first Australian records for P. longipes (previously recorded from Indonesia, New Guinea, Solomon Islands) from a series of specimens collected from King Park, Kutini-Payamu (Iron Range) NP, Qld (males and females ). This is the only Australian species exhibiting semi-metallic colouration, having a deep milky blue thorax and abdomen. It is likely to be confused with Sargus, but can be readily distinguished based on the generic characters.
Little is known regarding the biology of the Australian species, however, Woodley (2001) noted that some species were associated with fallen fruits in the forests of Panama, and decaying piles of grass and compost heaps in the United States of America.
Diagnosis. Small to medium sized (length 6-12 mm), slender, elongate species, with strong metallic colouration and occiput with a prominent fringe of posteriorly directed hair-like setae. Similar to Ptecticus, but distinguished by the: anterior ocellus farther from posterior ocelli than they are from each other, forming an elongated triangle; wings with vein R 2+3 arising distal to r-m; lower calypter with strap-like lobe present; and strong metallic colouration.
Distribution. Far northern Qld to central coast of NSW (Fig. 2).

Remarks.
With the transfer of C. gselli from Sargus to Cephalochrysa, there are now three recognized species of Sargus from Australia. According to White (1916), Sargus was previously unrecorded from Australia at the time, with Sargus meridionalis White, 1916 being the first species recognized from the continent. This was reinforced by Hill (1919: 460) in his description of S. gselli (= C. gselli), stating that Sargus "has been known in Australia by only one described species, S. meridionalis White. There are one or two additional species… from North Queensland (Kuranda)". Hardy (1932) later described the second species in the genus from Australia, Sargus darius Hardy, 1932, including a paratype from Kuranda, which is presumably the additional species referred to by Hill. It is possible that species names applied to the Australian fauna are erroneous, such as Sargus mactans Walker, 1859 (originally described from Indonesia), which has been used for specimens from Queensland. In a review of the Oriental Stratiomyidae, Brunetti (1923: 157) identified specimens of S. mactans deposited in the BMNH from "North Queensland". This Australian record was adopted by some workers (Hauser & Rozkošný, 1999: 13;Woodley, 2001: 226), however, S. mactans was not acknowledged by Hardy (1932) and the name has not been applied to material deposited in most Australian collections. Moreover, it seems unlikely that the southeast Asian fauna have travelled east of the Wallace Line. The identify of S. mactans from Australia has been made further complicated by the damaged type specimen from the BMNH (head and left with missing; Fig.  11), in addition to the lack of available key to species and authoritatively identified collection specimens. Therefore, we tentatively retain S. mactans as part of the Australian fauna until a much needed species-level revision can be completed for Sargus from the Oriental and Australian regions. Biology. According to James (1960), adults from the Nearctic are commonly found flying near or resting on leaves in sunlight, and visiting flowers such as Sedum (stonecrop, Crassulaceae), Isocoma vernonoides (goldenbush, Asteraceae), and Sambucus coetulea (elderberry, Adoxaceae), whereas the larvae breed in decaying vegetation, including leaves, turnip roots, and/or mammal excrement. Regarding the Australian species, S. meridionalis seems to decompose organic waste since it has been bred from human faeces ].