Revision of the South American window fly genus Heteromphrale Kröber, 1937 (Diptera, Scenopinidae)

Abstract The Neotropical window fly genus Heteromphrale Kröber, 1937 is revised. Two previously described species (Heteromphrale chilensis (Kröber, 1937) and Heteromphrale cyanops (Edwards, 1932)) are redescribed while a new species (Heteromphrale blanca sp. n.) is described from Argentina. The male of Heteromphrale chilensis and female of Heteromphrale cyanops are described and figured for the first time, and a key to species is presented.


Introduction
Window fl ies (Diptera: Scenopinidae) are a small family (ca. 420 species in 24 extant genera) of cosmopolitan asiloid fl ies with an adult body size rarely exceeding 5.0 mm. Scenopinids are distributed throughout all major biogeographical regions, but with signifi cant continental endemism at the genus level (Kelsey 1973).
Heteromphrale Kröber, 1937 is one of several genera of Scenopinidae found in the Neotropics, a region also including Brevitrichia Hardy, 1944 (also Nearctic), Irwiniana Kelsey, 1971, Jackhallia Nagatomi & Liu, in Nagatomi et al. 1994, Pseudatrichia Osten Sacken, 1877, Metatrichia Coquillett, 1900 (cosmopolitan), and Scenopinus Latreille, 1802 (cosmopolitan). Heteromphrale was erected by Kröber (1937) to accommodate his previously described species Pseudatrichia chilensis Kröber, 1928 from Chile, with Pseudatrichia being a highly distinctive genus to which this species clearly does not belong. In his monographic revision of world Scenopinidae, Kelsey (1969) subsequently transferred Pseudomphrale cyanops Edwards, 1932 to Heteromphrale as the second species in the genus. Th ese two previously described species of Heteromphrale were each known only from a single sex (i.e. the female of H. chilensis and male of H. cyanops). As a result of extensive collecting by Dr Michael Irwin in Chile and Argentina, the opposing sexes of both species are now available, along with males and females of a new species (H. blanca sp. n.) described herein. Heteromphrale is revised with all species diagnosed and fi gured, and a dichotomous key to species presented. Th e key to genera in  can be used to identify specimens to this genus, although the female of one species has a weakly emarginate posterior edge of sternite 8 (but not forming distinct posterolateral lobes as in Brevitrichia), and only one species has bulbous male epandrial lobes. As in recent papers using cybertaxonomic methods such as hypertext mark-up links to internet resources (e.g. online image databases, name registration in Zoobank, etc.) (Pyle et al. 2008;Winterton 2009), we have also extensively used such resources throughout the text.

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 fl ies with terminalia not rotated; therefore the ventral apodeme of the aedeagus described herein is physically located dorsally. Th e following collection acronyms are cited in the text: California Academy of Sciences, San Francisco, California, USA (CAS), Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany (DEI), California State Collection of Arthropods, Sacramento, California, USA (CSCA), Bohart Museum of Entomology, University of California, Davis, California, USA (UCDC), the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA (NMNH), and the Natural History Museum, London, United Kingdom (BMNH). Numbers quoted with individual specimens as MEI000000 are unique identifi ers in the therevid database MANDALA and are attached to each specimen as a yellow or white label (Kampmeier et al. 2004). Specimen images at diff erent focal points were taken using a digital camera and subsequently combined into a serial montage image using CombineZP. Higher-resolution digital images were also archived in Morphbank with embedded URL links between fi gure captions and Morphbank images. All new nomenclatural acts and literature are registered in Zoobank as per the recent proposed amendment to the International Code of Zoological Nomenclature for a universal register for animal names (Polaszek et al. 2005a,b;Pyle et al. 2008;ICZN 2008). Kröber 1937: 221. -Hardy 1966Kelsey 1969: 286;1971: 284;1973: 332;Woodley 2009: 651 . Cream-white with yellowish-brown suff usion; eyes contiguous in male, frons broader than ocellar tubercle in female; antennal fl agellum approximately twice length of scape and pedicel combined, attenuate and pyriform, notched apically; scutum light brown to dark grey, with cream-white to yellow patches marginally (pale area often more extensive in female); entire thorax overlain with glaucous pubescence; wing vein M 1 meeting vein R 5 , forming closed petiolate cell r 5 ; R 4 branching from R 5 along basal half of cell r 5 ; abdomen with tergites either dark brown-grey with pale white to yellow band posteriorly, or vivid white with orange-brown suff usion laterally (and medially in female); tergite 2 sensory setae well defi ned (Fig. 1); male epandrium split medially as two sclerites, halves sub-quadrangular with posterior margins fl ared or tapered laterally, or large and globose; epandrium not completely covering gonocoxite ventrally; gonocoxite and aedeagus extended anteriorly from anterior margin of epandrium a relatively short distance; gonocoxite irregular, largely reduced, with strongly sclerotized dorsal process; gonocoxal apodeme relatively thickened; hypandrium as paired lobes, size and shape variable, with margin of setae, but no large setal brushes; lateral aedeagal bulb present; distiphallus bifi d, recurved dorsally at base or straight, slender or slightly thickened, arms parallel or divergent. Female sternite 8 longer than tergite 8, almost level with cerci, broadly rounded or weakly emarginate (not forming distinct lobes posterolaterally); 6-7 acanthophorite spines present on lobes of well defi ned tergite 9+10; furca ring-like, dark-sclerotized; spermathecae paired, sclerotized and irregular-shaped; spermathecal sac simple, minute, elongate.

Comments.
Heteromphrale is closely related to Brevitrichia, a genus found primarily in western North America and throughout Central America (Kelsey 1969;). Heteromphrale can be diff erentiated from Brevitrichia by the shape of sternite 8 in the female (apically emarginate with rounded posterolateral lobes in Brevitrichia), male distiphallus short and thick (relatively long and thread-like in Brevitrichia) and the distiphallus straight (highly refl exed basally in Brevitrichia). Th e distiphallus of Brevitrichia can be greatly elongated, with the basiphallus refl exed upon itself up to 180° as found in the proratine genus Cyrtosathe Metz, 2005 (Winterton andMetz 2005). Th is complex arrangement of the distiphallus in Brevitrichia often projects anteriorly into the abdominal cavity and is supported by aedeagal guides formed by paired, blade-like extensions of the hypoproct; the aedeagus is largely contained within the genitalic capsule in Heteromphrale, with hypoproct extensions absent. Th e distinct dorsal processes (physically ventral) on the gonocoxites of Heteromphrale (Figs 2-3) are similar to those found in some species of Propebrevitrichia Kelsey, 1969(see Winterton 2005) and indicate a likely close relationship between these genera.
Distribution. Southern South America; recorded from Uruguay, Chile and Argentina.
Included species. Heteromphrale blanca sp. n., H. chilensis (Kröber) and H. cyanops (Edwards).   Diagnosis. Antennal fl agellum dark brown to black, conical and evenly tapered distally; mouthparts normal, nearly fi lling oral cavity; scutum without glabrous dorsocentral patches; wing with vein R 4 diverging from vein R 5 at point between one-quarter and one-half of cell r 5 ; abdomen dark with pale posterior band on tergites 2-5; tergite 2 sensory patch distinct as two small patches; male epandrium not bulbous, dense fringe of white setae along posterior margin; hypandrium lobes relatively large and sub-triangular; distiphallus with arms parallel; lateral aedeagal bulbs relatively large; female sternite 8 posterior edge rounded; acanthophorite spines elongate and fi nely tapered, wispy.

Key to
Description. Body length: 2.5-4.0 mm [male], 2.7-4.2 mm [female]. Head (Figs 4A-B, 5A-B). Frons, parafacial, face and gena cream-white to yellow; female frons with tan suff usion dorsomedially and surface slightly furrowed medially, sparsely distributed with small, pale setae; male frons with whitish pubescence and dark where eyes are proximate; occiput with yellow suff usion marginally, black medially; face white; fl agellum brown to black; scape pale yellow; pedicel yellowish-tan with a few minute pale setae; mouthparts normal-sized, nearly fi lling oral cavity; pale yellow, including prementum, labellum, labellar setae, and small cylindrical palpus. Th orax (Figs 5A-B, 6). Scutum black to grey, small pale yellow areas marginally (postpronotal lobe, notopleuron and supra-alar area), more extensive in female and additionally with yellow on anterior part of scutum adjacent to postpronotum, on postalar callus, and medially on posterior part of scutum; entire thorax overlain with dense glaucous pubescence; scutellum dark medially, yellow marginally (yellow area more extensive in female); scutum without pale setae, some present on postpronotal lobe, anepisternum and katepisternum; prosternum yellow; proepisternum and proepimeron yellow, sometimes with brown on posterior part; anepisternum grey pubescent, yellow in upper part; katepisternum grey pubescent, yellow in posterodorsal corner (in female, along most of dorsal margin); anepimeron grey pubescent anteriorly, yellow posteriorly; meron grey pubescent, except yellow dorsally; coxae light brown to orange; legs tan to dark yellow-orange; distal tarsomeres darker than rest of leg; haltere stem brown, knob white with brown suff usion dorsally; wing venation pale yellow; vein R 4 diverging from R 5 at point between one-quarter and one-half of cell r 5 . Abdomen (Fig. 6). Segments dark brown-grey with pale white-yellow band posteriorly; sternites dark browngrey; sparse pale setae on most segments; tergite 2 sensory patch large and distinct, divided medially into two small patches, patch concolorous with rest of tergite. Male genitalia (Figs 2A-B, 10A). Epandrium sub-quadrangular, outer margins tapered, dark brown in basal half and pale yellow in distal half, white setal fringe along margin; hypandrium lobes relatively large, triangular; gonocoxite with darkly sclerotized, narrowly acuminate, dorsal process; gonostylus complex, apparently fused to gonocoxites, with posteriorly directed margin fringed with setae, and hook-like process dorsally, inner lobe triangular and fused medially; gonocoxal apodeme broadly fl attened, curved medially; ejaculatory apodeme relatively elongate, directed anteriorly; lateral aedeagal bulbs large, round; distiphallus elongate, arms proximate and parallel, broadly curved ventrally at base then straight along distal length. Female genitalia (Fig. 9A-C). Sternite 8 with posterior edge rounded, with posterolateral part fringed with long wispy setae; acanthophorite spines elongate and curved, becoming wispy and hair-like.
Comments. Heteromphrale blanca sp. n. is very similar to H. cyanops in overall body color, but diff ers considerably in male genitalic morphology and in the shape of the female sternite 8. As in H. chilensis, the tergite 2 sensory patch is large and distinct, and is divided into two small patches with the setae directed medially. In males, the non-bulbous epandrium distinguishes this species and H. chilensis from H. cyanops, but the dense fringe of white setae along the posterior margin, distinguishes H. blanca sp. n. from H. chilensis. In females, the rounded sternite 8 distinguishes H. blanca sp. n. from H. cyanops, and the fringe of long wispy setae and elongate wispy acanthophorite spines distinguishes this species from H. cyanops and H. chilensis.

Distribution. Known only from Argentina (La Rioja, Salta and Tucuman Provinces).
Etymology. Th e specifi c epithet is a Latin adjective -blanca -meaning white, referring to the dense fringe of white setae along the posterior margin of the epandrium. Diagnosis. Antennal fl agellum orange brown, abruptly pear-shaped; female frons with extensive pile; mouthparts much smaller than oral cavity; scutum with glabrous, glossy dorsocentral spot (linear in female); wing with vein R 4 diverging from R 5 at point in basal quarter of cell r 5 ; abdomen vivid matte-white with brown suff usion laterally (also medially in female), and with dark brown spot encompassing tergite 2 sensory patch; tergite 2 sensory patch distinct as two small patches; male epandrium not bulbous, without dense fringe of setae; hypandrium lobes sub-triangular with scle-rotized lateral margins; distiphallus arms divergent; lateral aedeagal bulbs relatively small; female sternite 8 rounded posteriorly, without fringing elongate setae; acanthophorite spines robust and stout.

Heteromphrale chilensis (Kröber)
Redescription. Body length: 2.6-3.2 mm [male], 4.8 mm [female]. Head (Figs 4C-D, 5C-D). Frons cream-white, female frons with yellow to light brown patch dorsomedially, sometimes more extensive brown-orange suff usion, surface wrinkled, sparsely distributed with small, pale setae; parafacial in male dark orange medially, white along eye margin (in female entirely yellow); ocellar triangle grey pubescent, raised, with anterior ocellus slightly larger than posterior ocellus; occiput and postgena dark with pale yellow with orange-brown suff usion marginally; face white with brown suff usion; mouthparts pale, relatively small in size, much smaller than oral cavity; pale yellow, including labellum, labellar setae, and small cylindrical palpus; prementum in male dark orange (in female pale yellow); fl agellum orange-brown, abruptly pyriform, tapered distally; scape and pedicel brown with a few minute pale setae. Th orax (Figs 5C-D, 7). Scutum light brown to grey, yellow on postpronotal lobe, anterior part of scutum adjacent to postpronotum, notopleuron, supra-alar area and postalar callus (in female, with yellow more extensive in these areas); entire thorax overlain with dense glaucous pubescence; glossy black dorsocentral patches present at point posterior third of scutum, patches round in male, elongate in female, paired median brown vittae in anterior half; scutellum dark medially, pale marginally; prosternum yellow, bare; proepisternum and proepimeron orange (in female yellow); anepisternum orange in dorsal half and along posterior margin (in female yellow), except white along dorsal margin and grey to brown pubescent anteroventrally; katepisternum grey to brown pubescent, except orange in upper part (in female yellow); anepimeron white to yellow, darkened anteriorly; meron shining glossy brown, except white pubescent dorsally; legs pale cream with uniform or mottled brown suff usion, tibiae orange, with dorsal surface pale; hind tibia becoming darker distally; tarsi dark. Wing. Venation pale brown; vein R 4 diverging from R 5 at point in basal quarter of cell r 5 ; aberrant specimens with either spurious vein present between distal part of R 5 and C (Fig. 7B) or R 4 incomplete basally; haltere mostly cream-white. Abdomen (Fig. 7). Vivid matte-white to cream with brown suff usion laterally; dark brown band posteriorly (more obvious in female), tergite 2 with dark brown band level with and encompassing sensory setal patch; sternites white with brown suff usion laterally; sparse elongate setae on most segments. Male genitalia (Figs 2C-D, 10B). Epandrium brown basally and pale yellow marginally; sub-quadrangular with posterior margins tapered, fi ne setae along margin; hypandrium halves small, sub-triangular with multiple lobes directed posteromedially, dark sclerotized along anterior and lateral margins; gonocoxite with darkly sclerotized, acuminate, dorsal process; gonostylus large, posteriorly directed and united medially, apparently fused to gonocoxites; gonocoxal apodeme broadly fl attened, outer margin curved, inner margin straight; ejaculatory apodeme minute, directed ventrally; lateral aedeagal bulbs small; ventral apodeme dark sclerotized; distiphallus divergent laterally around gonostylus, medially directed process from between distiphallus projecting towards hypoproct, curved anteriorly, apex spatulate. Female genitalia (Figs 9C-E). Sternite 8 with posterior edge rounded, with longish setae around fringe; acanthophorite spines long and robust.
Comments. Originally described in Pseudatrichia, Kröber (1937) later erected Heteromphrale to accommodate this species. Although the female holotype is faded, encrusted with naphthalene and dust, and the abdomen is greasy, the distinctive bonewhite color of the abdomen is still observable, along with the brown coloration around the tergite 2 sensory patch. In the original description, Kröber (1928) described the fl agellum as red-yellowish color, but the antennae are now lost from the type specimen.
Heteromphrale chilensis is easily distinguished from other species of Heteromphrale by the glabrous dorsocentral patches on the scutum (elongate in females), mostly bonewhite coloured abdomen, basally bulbous antennal fi rst fl agellomere, and the relatively tiny mouthparts. As in H. blanca sp. n., the tergite 2 sensory patch is large and distinct, and is divided into two small patches with the setae directed medially, and the epandrium is not bulbous as in H. cyanops, but in H. chilensis there is no dense fringe of long white setae. Also like H. blanca sp. n., the female sternite 8 is rounded, but in H. chilensis, the edge is not fringed with long wispy setae, and the acanthophorite spines are robust.
Comments. Heteromphrale cyanops was originally described in the genus Pseudomphrale by Edwards (1932) based on a single male specimen from Uruguay. Edwards (1932) noted that the specimen was taken in a sandy spot near the shore, and also noted that the eye in life was deep blue in color; this eye color is retained in some specimens. Kelsey (1969) subsequently transferred the species to Heteromphrale. Heteromphrale cyanops is very similar to H. blanca sp. n. in overall body coloration, but is easily distinguished from both other species of Heteromphrale by the greatly enlarged, bulbous epandrium in the male, the shallowly emarginate posterior edge of sternite 8 in the female, and by the tergite 2 sensory patch being a relatively small, singular, narrowed patch.