A world review of the bristle fly parasitoids of webspinners

Background Dipteran parasitoids of Embioptera (webspinners) are few and extremely rare but known from all biogeographical regions except Australasia/Oceania. All belong to the fly family Tachinidae, a hyperdiverse and widespread clade of parasitoids attacking a variety of arthropod orders. Results The webspinner-parasitizing Diptera are reviewed based mostly on records from the collecting and rearing by Edward S. Ross. A new genus is erected to accommodate a new Afrotropical species, Embiophoneus rossi gen. et sp. nov. The genus Perumyia Arnaud is reviewed and a new species, Perumyia arnaudi sp. nov., is described from Central America while P. embiaphaga Arnaud is redescribed and new host records are given. A new species of Phytomyptera Rondani, P. woodi sp. nov., is described from Myanmar, representing the first report of a member of this genus obtained from webspinners. The genus Rossimyiops Mesnil is reviewed, R. longicornis (Kugler) is redescribed and R. aeratus sp. nov., R. fuscus sp. nov. and R. rutilans sp. nov. are newly described from the Oriental Region, and an updated key to species is given. Conclusions Webspinners were probably colonized independently at least four times by tachinids shifting from other hosts, most likely Lepidoptera. Supplementary Information The online version contains supplementary material available at 10.1186/s40850-022-00116-x.

after emerging as adults in search of females with which to mate. These circumstances have hampered the taxonomic study of webspinners because the neotenic females possess fewer diagnostic characters than males, yet males are rarely captured in galleries. The much-coveted males are most readily obtained by rearing from collected nymphs, from eggs obtained from fertilized females or by catching them at lights at night [12,13].
A major contributor to our knowledge of the Embioptera was Edward S. Ross (1915Ross ( -2016, who published on this group over a period of approximately 70 years. He was an avid collector who travelled the world in search of webspinners. He eventually amassed a collection of about 350,000 specimens housed in the California Academy of Sciences in San Francisco (CAS) [14]. On very rare occasions Ross reared dipteran parasitoids from his live cultures of webspinners, all of them belonging to the family Tachinidae. These specimens were pinned and are also housed in CAS. The reared tachinids, 21 in number, were borrowed by us and form the basis for this taxonomic review.
The Tachinidae are a major clade of calyptrate Diptera with ca. 8500 described species [15,16], all developing as endoparasitoids of at least 15 orders of arthropods including Lepidoptera (~ 60% of host species), Coleoptera (~ 15%), Heteroptera (~ 13%), Hymenoptera (~ 6%), Polyneoptera (Embioptera, Dictyoptera, Orthoptera, Phasmatodea) and even centipedes and scorpions [17,18]. Only three species are currently known to parasitize webspinners: Perumyia embiaphaga Arnaud in Peru [19], Rossimyiops exquisitus (Richter) in Iran and Yemen, and Rossimyiops whiteheadi Mesnil in South Africa [20]. To these are added below a new monotypic genus from Africa, a new species of Perumyia Arnaud from Mexico and Nicaragua, a new species of Phytomyptera Rondani from Myanmar, and three new species of Rossimyiops Mesnil from Thailand and Myanmar. Keys are provided to the known species of Perumyia and Rossimyiops and general aspects of the webspinner-tachinid association are discussed.
Diagnosis Small to medium-sized flies, mostly black in ground color. Compound eye bare. Two reclinate orbital setae (both sexes). Facial ridge slightly convex, with erect setae above vibrissa on lower 4/5. Lower facial margin not visible in lateral view in front of vibrissal insertion. Gena about 1/5 of compound eye height. Gena higher than width of parafacial measured at level of base of antenna. Postpedicel 4.0-4.5 times as long as pedicel. Four postsutural dorsocentral setae; one presutural and three postsutural intra-alar setae; first postsutural supra-alar seta stronger than other mesonotal setae, much longer than first postsutural intra-alar seta and longer than notopleural setae. Prosternum with a pair of fine setae laterally. Postpronotum with three setae arranged in a line. Katepimeron bare. Apical scutellar setae well developed. Anterior and posterior lappets of metathoracic spiracle about equal in size. Vein R 4 + 5 with setae from base to junction with crossvein r-m. Wing cell r 4 + 5 long petiolate. Preapical anterodorsal seta of fore tibia at least as long as preapical dorsal seta. Hind tibia with three dorsal preapical setae. Mid-dorsal depression of syntergite 1 + 2 extending on anterior half. Abdominal tergites 3 and 4 without median discal setae. Puparium light brown and reddish. Stigmatal plates located on prominent black protuberances.
Etymology The generic name is a composite word from Greek, with prefix "εμβιος", i.e., "lively" (the prefix of the name Embioptera), and suffix "φονεύς", i.e., "murderer", referring to the parasitoid habits of the new taxon. The name is masculine.
Hosts Embioptera. Description (male) Body length: 4.6 mm. Color (Fig. 1). Head brown. Scape and pedicel light brown. Postpedicel brown. Arista yellow. Palpus yellow. Thorax brown, mostly covered with whitish pruinosity except on four dark vittae. Upper and lower calypters yellowish. Wing hyaline with a light brown shadow on anterior part, along costa. Tegula and basicosta brown. Wing veins brown. Scutellum mainly dark brown, covered with pruinosity. Abdomen black; tergites 3 and 4 with a narrow anterior band of pruinosity. Femora and tibiae dark brown. Head (Fig. 2a). Frons at its narrowest point about 4/5 as wide as a compound eye width in dorsal view. Outer vertical seta present and well developed. Ocellar seta well developed and latero-proclinate. Frontal setae descending to level of arista insertion. Fronto-orbital plate more or less setulose. Two proclinate orbital setae. Parafacial bare below lowest frontal seta. Parafacial at its narrowest point approximately 2/5 of width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point 1/4 of distance between inner margin of compound eye and antennal insertion. Vibrissa inserted at level of lower facial margin. Face and lower facial margin not visible in lateral view in front of vibrissal insertion. Genal dilation well developed. Ventral and dorsal part of occiput with a majority of black setae. Postpedicel 4.2 times as long as pedicel. Arista bare and thickened on proximal 2/3. Second aristomere 1.5 times as long as its diameter. Prementum stubby, 2 times as long as wide. Palpus apically enlarged. Thorax. Three presutural and three postsutural acrostichal setae; three presutural dorsocentral setae. Katepisternum with three setae. Scutellum with five pairs of marginal setae (basal, two laterals, subapical, apical); subapical scutellar setae well developed; apical scutellar setae strong and crossed; preapical scutellar setae absent (Fig. 2b). Wing (Fig. 1b). Second costal section (Cs 2 ) setulose ventrally. Costal spine not differentiated from other costal setae. Veins R 1 and M 4 bare. Bend of vein M 1 forming a nearly right angle. Bend of vein M 1 without stub. Section between crossveins r-m and dm-m shorter than section between dm-m and postangular section of vein M 1 . Cell r 4 + 5 with a petiole about 1.3 times postangular section of vein M 1 . Vein CuA + CuP not reaching wing margin. Legs. Legs stout. Fore coxa with anteroventral surface bare. Anterior tarsus enlarged (Fig. 2c). Fore tibia with preapical anterodorsal seta about same length of dorsal preapical seta. Mid tibia with one anterodorsal seta. Anterodorsal setae of hind tibia irregularly spaced and irregular in size. Abdomen (Fig. 1c). Tergites 1 + 2 and 3 without median marginal setae. Tergites 4 with a row of short erect marginal setae. Tergite 5 very short, about 0.6 times as long as tergite 4. Male terminalia (Fig. 2g, h). Epandrium short and convex. Cerci well developed, covered with setae; apical third of cerci separated and tips gently converging medially, in posterior view. Phallus, surstylus and hypandrial complex not examined, missing in the holotype. Puparium. Ground color from light brown to reddish, posterior spiracle black. Posterior spiracle horn-like (i.e., with a relatively large, sub-elliptical base, gently tapering distally with rounded apex) (Fig. 2d): lateral surface with a cobblestone-like microsculpture, posterior end smooth with several small, sub-elliptical openings (Fig. 2e). Surface evenly covered with minute, spine-like, protuberances (Fig. 2f ).

Embiophoneus rossi
Distribution Ivory Coast, Liberia, Mozambique. Wing veins light brown. Legs reddish-brown in ground color. Scutellum mainly brown with pruinosity. Abdomen mostly light brown and partly orange laterally, with a band of whitish pruinosity on posterior part of tergites. Tergites 3 and 4 with a band of pruinosity on anterior 1/3. Head (Fig. 4a). Outer vertical seta present and well developed (both sexes). Frontal setae descending to level of arista insertion. Fronto-orbital plate with a row of reclinate or medioclinate setae and some hair-like setae. Parafacial at its narrowest point approximately 2/5 width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point approximately 1/4 distance between inner margin of compound eye and antennal insertion. Facial ridge slightly convex and with erect setae above vibrissa on lower 3/5. Vibrissa inserted at level of lower facial margin. Face not visible in lateral view. Lower facial margin slightly visible in lateral view in front of vibrissal insertion. Genal dilation developed. Ventral and dorsal part of occiput with majority of white setae. Antenna longer than height of gena. Postpedicel 3 times as long as pedicel (Fig. 4a). Arista thickened on proximal 2/3 (Fig. 4b). First aristomere very short, shorter than wide. Second aristomere 2 times as long as its diameter. Palpus apically enlarged. Thorax. Scutum with three presutural and three postsutural acrostichal setae; three presutural and three postsutural dorsocentral setae; three postsutural intra-alar setae; first postsutural supra-alar seta longer than notopleural setae. Postpronotum with two setae. Katepisternum with two setae. Katepimeron bare. Scutellum with three pairs of marginal setae (basal, subapical, apical); apical scutellar setae hair-like and crossed (Fig. 4c); preapical scutellar setae absent; anterior and posterior lappets of metathoracic spiracle about equal in size. Wing (Fig. 3b). Costal spine as long as crossvein r-m. Vein R 1 bare. Vein R 4 + 5 with two setae at base. Bend of vein M 1 with stub as long as crossvein r-m. Cell r 4 + 5 with petiole 0.9 times as long as the postangular section of vein M 1 . Section of vein M 1 between crossveins r-m and dm-m shorter than section between dm-m and bend of vein M 1 . Legs. Preapical anterodorsal seta of fore tibia longer than dorsal preapical seta. Hind tibia with three dorsal preapical setae. Preapical posteroventral seta of hind tibia shorter than preapical anteroventral seta. Anterodorsal setae of hind tibia irregular in size. Abdomen (Fig. 3c). Tergites 3 with one pair of median marginal setae; tergite 4 with a complete row of marginal setae. Tergite 5 approximately as long as tergite 4. Male terminalia (Fig. 4 d, e). Epandrium short and convex with well-developed anterior prolongation. Cerci not fused medially, more or less subparallel and distally rounded in lateral view, more or less sharpened in posterior view. Cercus with strong setae and covered by hair-like setae. Surstylus very short, not Remarks Embiophoneus rossi likely belongs to the Eryciini + Goniini clade (Exoristinae) based on the combination of setulose prosternum, strong first postsutural supra-alar seta, convex facial ridge with a row of strong setae above vibrissa and cerci not fused medially. The dissected female had no eggs stored in uterus; thus, it is not possible to ascertain whether Embiophoneus is micro-(i.e., Goniini) or macro-ovolarviparous (i.e., Eryciini) [21]. However, Embiophoneus is likely a member of Goniini, with which it shares a short oviscapt [19]. Among Goniini, Embiophoneus is similar to the Palaeotropical genus Prosopodopsis Townsend, from which it is readily distinguishable by the long petiolate wing cell r 4 + 5 .
Diagnosis (modified from Arnaud [19]) Small to medium-sized flies. Compound eye bare. Frons at its narrowest point 1.0-1.2 times as wide as compound eye width in dorsal view (both sexes). Two proclinate orbital setae (female). Ocellar seta well developed and reclinate. Parafacial bare below lowest frontal seta. Gena about 1/5 of compound eye height. Arista micropubescent, thickened nearly to tip. Prosternum setulose. Scutellum with three or four marginal setae. Wing hyaline. Cell r 4 + 5 closed and long petiolate. Mid femur with two or more anterior setae. Mid tibia with two strong anterodorsal setae. Mid-dorsal depression of syntergite 1 + 2 extending to posterior margin. Tergite 3 and 4 without median discal setae.

Perumyia embiaphaga
Description Body length: 5 mm. Color (Fig. 3). Head brownish covered with silver-grey pruinosity. Scape, pedicel and postpedicel yellowish. Palpus yellowish. Thorax reddish-brown in ground color. Presutural area with whitish pruinosity except on four dark vittae. Upper and lower calypters whitish. Tegula black and basicosta yellow. Remarks The male shows all diagnostic characters of Perumyia embiaphaga, except for vein R 4 + 5 bearing two setae at base instead of six, which likely represents intraspecific variability.
Perumyia arnaudi sp. nov. LSID urn:lsid:zooba nk. org:act:4DB1244A-179C-4D28-85CA-FDE3188F7B2D. Diagnosis Body length about 4-5 mm. Frons at its narrowest point as wide as compound eye in dorsal view (both sexes). Second aristomere 3.5-4.0 times as long as its diameter. Apical scutellar setae absent. Vein R 4 + 5 with short setae from base approximately halfway to crossvein r-m. Bend of vein M 1 with a stub longer than crossvein r-m. Abdomen brown and partly reddish laterally, tergites 3 and 4 with pruinosity on anterior 1/3. Description (male, differences with females are given) Body length: 4.7 mm. Color (Fig. 5 a, b). Head dark brown covered with silvery-grey pruinosity. Scape and pedicel brown (male) or yellowish (female). Postpedicel mostly dark brown shading into yellowish at junction with pedicel. Palpus yellowish. Thorax dark brown. Presutural area with whitish pruinosity except on four dark vittae. Upper and lower calypters whitish. Wing veins brown or yellowish. Tegula black and basicosta yellow. Legs brown in ground color. Scutellum mainly brown with pruinosity. Abdomen brown and partly reddish laterally. Tergites 3 and 4 with pruinosity on anterior 1/3. Terminalia brown. Head (Fig. 5c, d). Frons at its narrowest point as wide as compound eye in dorsal view (both sexes). Outer vertical seta present and well developed (both sexes). Frontal setae descending slightly below level of arista insertion. Fronto-orbital plate with a row of reclinate or medioclinate setae and some airlike setae lateral to row of frontal setae. Parafacial at its narrowest point approximately 2/5 width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point 1/4 distance between inner margin of compound eye and antennal insertion. Facial ridge slightly convex and with erect setae above vibrissa on lower 3/5. Vibrissa inserted at level of lower facial margin. Face not visible in lateral view. Lower facial margin slightly visible in lateral view in front of vibrissal insertion. Genal dilation developed. Ventral and dorsal part of occiput with a majority of white setae. Antenna longer than height of gena. Postpedicel 5 times as long as pedicel. Arista thickened on proximal 4/5. First aristomere very short, shorter than wide. Second aristomere 3.5-4.0 times as long as its diameter (Fig. 6d, e). Palpus apically enlarged. Thorax. Scutum with three presutural and three postsutural acrostichal setae; three presutural and three postsutural dorsocentral setae; three postsutural intra-alar setae; first postsutural supra-alar seta longer than notopleural setae. Postpronotum with two setae. Katepisternum with two setae. Katepimeron bare. Scutellum with three pairs of marginal setae (basal, lateral, subapical) (Fig. 6c); apical and preapical scutellar setae absent. Anterior and posterior lappets of metathoracic spiracle about equal in size. Wing (Fig. 5e, f ). Costal spine as long as crossvein r-m (Fig. 6f ). Vein R 1 bare. Vein R 4 + 5 with short setae from base approximately halfway to crossvein r-m. Bend of vein M 1 with stub longer than crossvein r-m. Cell r 4 + 5 with petiole 1.1 times as long as postangular section of vein M 1 . Section of vein M 1 between crossveins r-m and Remarks The Neotropical genus Perumyia was erected by Arnaud [19] for P. embiaphaga. This species was described on seven specimens emerged from a Peruvian species of Clothoda [19]. The puparia of the examined specimens of Perumyia were enveloped in embiid silk, i.e., not enclosed within the remains of the host, suggesting that the larva leaves the host body before pupating [19]. The affinities of Perumyia are unclear but it appears it may form a monophylum with the New World goniine genus Distichona Wulp. Perumyia and Distichona share the characteristic reclinate ocellar setae of the Gonia Meigen group of genera, as well as the following character states: narrow parafacial (parafacial can be bare or with setae in Distichona), strong rows of both reclinate orbital setae and proclinate setae on facial ridge. Distichona includes 8 species [16]-note that 11 species is given in Wood & Zumbado [22]-ranging from southern Canada to Peru and differs from Perumyia by the non-petiolate wing cell r 4 + 5 , likely a plesiomorphic condition. The hosts of Distichona remain unknown, despite a recent report that suggested otherwise. A Mexican study published in English by Salas-Araiza [23] and in Spanish by Salas-Araiza & González-Márquez [24] reported Distichona auriceps Coquillett as a newly recorded parasitoid of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). As pointed out by O'Hara & Cerretti [25], this record was based on a misidentification; the tachinid identified as D. auriceps in Fig. 1   Diagnosis Small to medium-sized flies, body length 2-5 mm. Frons of equal width or slightly wider than compound eye width in dorsal view (both sexes). Arista thickened at least on basal 2/3. Second aristomere 3-10 times as long as wide. Upper part of head with several rows of black setae behind postocular row (occipital area and genal dilation with only black setae). Prosternum setulose. Three postsutural intra-alar setae. Proepimeral seta curved downward. Scutellum with strong, convergent, subparallel or slightly diverging, subapical setae, apical setae present but very small. Vein R 4 + 5 with a single large seta at base. Vein M 1 with bend evenly curved or with apical section obliterated. Cell r 4 + 5 not petiolate.
Distribution All biogeographic regions except Australasia/Oceania.
Included species See O'Hara et al. [16].  Second aristomere approximately 7 times as long as its diameter (Fig. 8a). Prementum 5 times as long as wide. Palpus apically enlarged. Thorax. Scutum with two presutural acrostichal setae; two presutural and two postsutural dorsocentral setae; first postsutural supra-alar seta shorter than notopleural setae. Proepimeral seta strong and curved downward. Postpronotum with two setae. Katepisternum with three setae. Scutellum with three pairs of strong marginal setae (basal, lateral, subapical), apical scutellar setae thin and crossed; preapical scutellar setae straight and erect. Anterior and posterior lappets of metathoracic spiracle about equal in size. Wing (Fig. 7c). Second costal section (CS 2 ) setulose ventrally. Costal spine as long as crossvein r-m. Vein R 1 bare. Vein M 4 bare. Crossvein dm-m present. Vein M 1 with a distinct bend and reaching wing margin. Bend of vein M 1 forming an obtuse angle. Vein M 1 without stub. Section between crossvein r-m and dm-m approximately as long as section between dm-m and bend of vein M 1 . Cell r 4 + 5 open (Fig. 8b). Legs. Preapical anterodorsal seta of fore tibia about the same length of dorsal preapical seta. Mid tibia with one anterodorsal seta. Hind tibia with two dorsal preapical setae. Preapical posteroventral seta of hind tibia shorter than preapical anteroventral seta. Anterodorsal setae of hind tibia unarranged and irregular in size. Posterodorsal margin of coxa bare. Abdomen (Fig. 7d). Mid-dorsal depression of syntergite 1 + 2 extending on anterior half. Syntergite 1 + 2 without median marginal setae. Both tergites 3 and 4 with one pair of median marginal setae; both without median  (Fig. 8c, d). Epandrium short and convex, with well-developed anterior prolongation. Cerci not fused medially and more or less subparallel, apically pointed and curved anteriorly in lateral view. Cercus with strong erect setae on dorsal surface. Surstylus not fused to epandrium, approximately as long as cercus. Surstylus bent posteriorly in lateral view. Surstylus with strong setae on distal surface. Phallus stout. Epiphallus absent. Basal extensions of basiphallus not developed. Medioventral sclerite of distiphallus well developed. Distiphallus with a pair of narrow, membranous, lobe-like, lateroventral projections, covered with scale-like spinules (pleurohypophallus of Andersen [27]); extensions of dorsal sclerite of distiphallus (dorsal plate of Andersen [27]) wrench-like distally; lateroventral lobes of distiphallus well developed and covered with four rows of scale-like spinules (Fig. 8c) (Fig. S1 in Additional file 1).
Remarks Phytomyptera is a large and widespread genus of tachinines with 61 described species [16]. However, the actual diversity of this genus is much higher, given the large number of undescribed species preserved in museum collections (P.C., unpublished) and the lack of taxonomic revisions. Hosts are known only for a handful of species and are all microlepidopterans [27][28][29]. Despite the difference in host preference, morphological evidence supports P. woodi sp. nov. as a member of Phytomyptera. The monophyly of Phytomyptera is well supported by both molecular and morphological evidence [30]. The relationship of P. woodi sp. nov. to other species of Phytomyptera is still unclear. Phytomyptera woodi is readily distinguishable from the only other Oriental species, P. minuta (Townsend), as follows: wing vein M 1 reaching wing margin (M 1 not reaching wing margin in P. minuta), crossvein dm-m present (absent in P. minuta) and black palpus (yellow in P. minuta).
Diagnosis (modified from Cerretti et al. [20]) Small to medium-sized flies, body length varying from 2 to 6 mm. Compound eye bare. Male frons extremely narrow, and frontal vitta concealed by medial margin of fronto-orbital plate. Frons larger in female. Inner vertical setae parallel or crossed (only in Oriental species). Two or more proclinate orbital setae (female). Occiput with black setae only. Arista bare, thickened on proximal 1/5-1/2. Anterior and posterior lappets of metathoracic spiracle about equal in size. Apical scutellar setae crossed and horizontal or absent. Posterodorsal margin of hind coxa bare or with one strong seta (only in Oriental species). Mid-dorsal depression on abdominal syntergite 1 + 2 not extended posteriorly to posterior margin of that segment. Marginal setae on tergites 3, 4 and 5 "shifted" anteriorly into subdiscal position. Dorsolateral lobes of distiphallus well developed and "shifted" anteriorly. Surstylus distally bent posteriorly.

Included species:
Rossimyiops achilleae (Kugler, 1972 of compound eye height. Postpedicel 2 times as long as pedicel. Prosternum bare. Wing mostly hyaline, slightly smoky anterodistally. Vein R 4 + 5 bare. Cell r 4 + 5 closed at wing margin. Posterior margin of hind coxa with 1 strong seta. Abdomen dark brown without pruinosity. Abdominal discal setae absent. Male: epandrium and surstyli not fused. Description (male) Body length: 3.6 mm. Color (Fig. 9). Head black in ground color, covered with pruinosity. Scape and pedicel reddish-yellow. Postpedicel reddish-yellow proximally, shading into light brown distally. Palpus yellowish. Thorax dark brown. Presutural area without pruinosity and not showing longitudinal dark vittae. Upper and lower calypter brown with barely visible bronze reflections. Wing mostly hyaline, slightly darkened anterodistally (Fig. 9b). Tegula dark brown, basicosta light brown. Wing veins light brown to yellowish. Scutellum brown. Legs brown. Abdomen black, without pruinosity (Fig. 9c). Terminalia brown. Head (Fig. 10a). Frons at its narrowest point about 1/10 as wide as compound eye in dorsal view. Outer vertical seta not distinguishable from the rest of postocular setae. Inner vertical setae well developed and crossed. Ocellar seta well developed and proclinate. Frontal setae descending to upper margin of pedicel. Fronto-orbital plate bare. Proclinate and reclinate orbital setae absent. Parafacial at its narrowest point approximately 3/5-4/5 of width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point 2/3 of minimum distance between inner margin of compound eye and antennal insertion. Parafacial bare below lowest frontal seta. Facial ridge slightly convex with setae above vibrissa on lower 1/5. Lower facial margin slightly visible in lateral view in front of vibrissal insertion. Gena about 1/10 of compound eye height. Genal dilation well developed. Postpedicel 2 times as long as length of pedicel. Arista bare and thickened on proximal 1/2. Prementum stubby, 1.8 times as long as wide. Palpus apically enlarged. Thorax (Fig. 10b). Scutum with one presutural acrostichal seta; two presutural and two postsutural dorsocentral setae; two postsutural intraalar setae separated by a distance about equal to distance between first seta and suture; first postsutural supra-alar seta longer than notopleural setae. Prosternum bare. Posterior proepimeral seta upwardly curved. Postpronotum with two setae. Katepisternum with two setae. Scutellum with three pairs of marginal setae (basal, subapical,  (Fig. 10c); apical scutellar setae crossed; subapical scutellar setae shorter than apical setae; lateral scutellar setae absent. Wing (Fig. 9b). Costal spine not distinguishable from other costal setae. Veins R 1 and R 4 + 5 bare. Bend of vein M 1 forming an obtuse angle. Section of vein M 1 between crossveins r-m and dm-m approximately as long as section between dm-m and bend of vein M 1 . Cell r 4 + 5 closed at wing margin. Legs. Preapical anterodorsal seta of fore tibia visibly longer than dorsal preapical seta. Mid tibia with one well-developed anterodorsal seta, a weaker anterodorsal seta distally. Hind tibia with two dorsal preapical setae. Preapical posteroventral seta of hind tibia about as long as preapical anteroventral seta. Posterodorsal margin of hind coxa with one strong seta. Abdomen (Fig. 9c). Mid-dorsal depression of syntergite 1 + 2 extending on anterior half. Syntergite 1 + 2 without marginal setae. Tergite 3 with one pair of median marginal setae, tergite 4 with a row of marginal setae. Both tergites 3 and 4 without median discal setae. Tergite 5 about 7/8 as long as tergite 4. Male terminalia (Fig. 10d, e). Epandrium short and convex; anterior prolongation not developed. Cerci not fused medially, more or less subparallel and distally pointed in posterior view. Cercus gently bent anteriorly in lateral view. Cercus with strong setae on lateral surface and covered by thin hair-like setae. Surstylus not fused to epandrium, approximately as long as cercus. Surstylus with distal third bent postero-medially in lateral view; with short weak setae on laterodistal surface. Phallus long and straight. Epiphallus in parabasal position, well developed. Medioventral sclerite of distiphallus present; extension of dorsal sclerite of distiphallus developed; dorsolateral lobe of distiphallus well developed, with fine short hair-like setae. Pregonite large and ventrally pointed, posterior margin with a row of stout setae. Postgonite long, narrow, slightly curved. Bacilliform sclerite stick-like. Phallus apodeme robust with a well-developed phallic guide. Hypandrium well developed, medial plate of short and concave; hypandrial arms short, narrow, not fused. Puparium. Not preserved in examined specimens.
Distribution Thailand.
Etymology The specific epithet "aeratus" means "bronze-colored". It should be treated as a Latin adjective.
Type  Cerretti, 2009 Rossimyiops  Description (male) Body length: 3 mm. Color (Fig. 11). Head black in ground color, covered with weak pruinosity. Scape, pedicel and postpedicel brown. Palpus brown. Thorax black. Presutural area without pruinosity and not showing longitudinal dark vittae. Upper and lower calypter brown. Wing brownish, pigmented especially on anterior part. Tegula and basicosta blackish brown. Wing veins brown. Legs black. Abdomen black, without pruinosity. Terminalia blackish. Head (Fig. 11b). Frons at its narrowest point about 1/10 as wide as compound eye in dorsal view. Outer vertical seta not distinguishable from the rest of postocular setae. Inner vertical setae well developed and crossed. Ocellar seta well developed and proclinate. Frontal setae descending to middle of pedicel. Fronto-orbital plate bare. Proclinate and reclinate orbital setae absent. Parafacial at its narrowest point approximately 1/4 of width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point 1/4 of minimum distance between inner margin of compound eye and antennal insertion. Parafacial bare below lowest frontal seta. Facial ridge slightly convex, with setae above vibrissa on lower 1/4. Lower facial margin well visible in lateral view in front of vibrissal insertion. Gena about 1/10 of compound eye height. Genal dilation well developed. Postpedicel 1.5 times as long as pedicel. Arista thickened on proximal 1/4. Prementum stubby, 1.9 times as long as wide. Palpus apically enlarged. Thorax. Scutum with two presutural acrostichal setae; two presutural and three postsutural dorsocentral setae; two postsutural intra-alar setae separated by a distance greater than distance between first seta and suture; first postsutural supra-alar seta longer than notopleural setae. Prosternum bare. Proepimeral seta curved downward. Postpronotum with two setae. Katepisternum with two setae. Scutellum with three pairs of marginal setae (basal, subapical, apical); apical scutellar setae crossed; subapical scutellar setae shorter than apical setae. Wing (Fig. 11c).

Rossimyiops austrinus
Costal spine not distinguishable from other costal setae. Veins R 1 and R 4 + 5 bare. Bend of vein M 1 forming an obtuse angle, without stub. Section of vein M 1 between crossveins r-m and dm-m approximately as long as section between dm-m and bend of vein M 1 . Cell r 4 + 5 with a petiole 1.1 times as long as postangular section of vein M 1 . Legs. Preapical anterodorsal seta of fore tibia longer than dorsal preapical seta. Mid tibia with two anterodorsal setae. Hind tibia with two dorsal preapical setae. Preapical posteroventral seta of hind tibia about as long as preapical anteroventral seta. Posterodorsal margin of hind coxa with one strong seta. Abdomen (Fig. 11d). Mid-dorsal depression of syntergite 1 + 2 extending on anterior half. Syntergite 1 + 2 with two pairs of marginal setae. Tergites 3 with one pair of median marginal setae, tergite 4 with a row of marginal setae. Both tergites 3 and 4 without median discal setae. Tergite 5 about 4/5 as long as tergite 4. Male terminalia (Fig. 11e, f ). Epandrium short and convex; anterior prolongation not developed. Cercal prongs closely abutted medially (not fused); basal two-thirds of cerci wide in posterior view, distal third strongly pointed. Surstylus approximately as long as cercus. Phallus, surstylus and hypandrial complex not examined, missing in the holotype. Puparium. Not preserved in examined specimens.
Distribution Thailand.

Rossimyiops longicornis
References Cerretti et al. [20] [taxonomic review] Description (male, female) Body length: ca. 5 mm. Color (Fig. 12). Head black (male) or reddish (female) in ground color, covered with pruinosity. Scape and pedicel reddish-yellow. Postpedicel reddish-yellow, darkened at tip. Palpus reddish. Thorax brown (male) or reddish (female). Presutural area with whitish pruinosity except on 4 brown vittae (only in female). Legs brown in male, reddish in female. Upper and lower calypter light brown (male) or whitish (female). Wing brownish on anterior surface. Tegula and basicosta brown. Wing veins light brown. Scutellum brown (male) or reddish (female). Abdomen brown (male) or reddish (female). Tergite 3 and 4 with a narrow anterior band of pruinosity interrupted along midline. Terminalia brownish. Head (Figs. 12c, d,  13c). Frons at its narrowest point about 1/10 (male), 1/2 (female) as wide as compound eye in dorsal view. Outer vertical seta not distinguishable from the rest of postocular setae in male and well developed in female. Inner vertical setae well developed and crossed. Ocellar seta Fig. 13 Rossimyiops rutilans sp. nov., a male paratype, abdomen in dorsal view. b female paratype, abdomen in dorsal view. c male paratype, head in lateral view at SEM. d male paratype, thorax and posterior proepimeral seta at SEM. e thorax in dorsal view at SEM. f scutellum in dorsal view at SEM. g-h male terminalia, g in lateral view, h in posterior view. Scale bar 500 μm well developed and proclinate. Frontal setae descending to the upper margin of pedicel. Fronto-orbital plate bare. Reclinate orbital setae absent in male, one or two in female (asymmetric in female paratype). Parafacial, at its narrowest point approximately 1/2 (male), 3/5-4/5 (female) of width of postpedicel at mid length. Parafacial measured ventrally at its narrowest point 1/4 (male), 2/5 (female) of minimum distance between inner margin of compound eye and antennal insertion. Parafacial bare below lowest frontal seta. Facial ridge slightly straight with erect setae above vibrissa on lower 1/5. Lower facial margin not visible in lateral view in front of vibrissal insertion. Gena about 1/10 of compound eye height. Genal dilation well developed. Postpedicel 2.2 times as long as pedicel. Arista thickened on proximal 2/5. First aristomere very short, no longer than wide. Second aristomere as long as wide. Prementum 3 times as long as wide. Palpus apically enlarged. Thorax (Fig. 13d-f ). One presutural acrostichal setae; two presutural and three postsutural dorsocentral setae; two postsutural intraalar setae separated by a distance about equal to distance between first seta and suture; first postsutural supra-alar seta longer than notopleural setae. Prosternum with two strong setae. Posterior proepimeral seta curved downward (Fig. 13d). Postpronotum with two setae. Katepisternum with two setae. Scutellum with three pairs of marginal setae (basal, subapical, apical) (Fig. 13f ); apical scutellar setae crossed; subapical scutellar setae as long as apical setae. Wing (Fig. 12e, f ). Costal spine not distinguishable from other costal setae. Vein R 1 and R 4 + 5 bare. Bend of vein M 1 forming an obtuse angle. Section of vein M 1 between crossveins r-m and dm-m approximately as long as section between dm-m and bend of vein M 1 . Cell r 4 + 5 closed at wing margin. Legs. Preapical anterodorsal seta of fore tibia visibly longer than dorsal preapical seta. Mid tibia with two anterodorsal setae. Hind tibia with two dorsal preapical setae. Anteroventral surface of fore coxae completely bare. Preapical posteroventral seta of hind tibia as long as preapical anteroventral seta. Posterodorsal margin of hind coxa with one strong seta. Abdomen (Fig. 13a, b). Mid-dorsal depression of syntergite 1 + 2 extending on anterior half. Syntergite 1 + 2 without marginal setae. Tergites 3 with one pair of median marginal setae, tergite 4 with a row of marginal setae. Both tergites 3 and 4 without median discal setae. Tergite 5 as long as tergite 4. Male terminalia (Fig. 13g, h). Epandrium very short and convex; anterior prolongation not developed. Cerci not fused medially and cercal prongs standing widely apart, distally pointed in posterior view. Cercus pointed and apically curved anteriorly in lateral view. Basal half of cercus with strong erect setae on apical dorsal surface. Surstylus broad and fused to epandrium, longer than cercus. Surstylus with short weak setae on laterodistal surface. Phallus short. Epiphallus in parabasal position, very narrow and curved. Medioventral sclerite of distiphallus present; extensions of dorsal sclerite of distiphallus not developed; dorsolateral lobe of distiphallus not developed. Pregonite broad lobe-like. Postgonite very narrow and almost straight. Bacilliform sclerite not differentiated. Phallus apodeme robust with a well-developed and wide phallic guide, concave in anterior view. Hypandrium well developed, medial plate concave, hypandrial arms narrow and firmly fused postero-medially, entirely encircling base of phallus. Puparium. Sub-cylindrical in shape. Roundly convex anteriorly, tapering toward distal fourth and ending in two small subconical spiracular projections (spiracular openings not visible at 90x magnification). Reddish in ground color, generally smooth but covered with microspines. One of the puparia was covered with remains of host.
Distribution Myanmar.

Rossimyiops subapertus
References Cerretti  Remarks The three new species described here, R. aeratus sp. nov., R. fuscus sp. nov. and R. rutilans sp. nov., represent the first records of Rossimyiops from the Oriental Region. The new species differ from their congeners by the presence of one strong seta on the posterior margin of the hind coxa and inner vertical setae crossed.
Our report of five specimens of R. longicornis (Kugler) that emerged from webspinners reared by Ross confirm the association of Rossimyiops with webspinners, an interaction previously known only for R. exquisitus and R. whiteheadi [20]. Cerretti et al. [20] and Kugler [32] remarked on the high intraspecific variability of R. longicornis and we also observed this in the specimens we examined.

Discussion
Only two insect orders include parasitoids of webspinners: Diptera and Hymenoptera. These two hyperdiverse clades account for the vast majority of insect parasitoids, with the latter much more diverse in this respect. The parasitism of webspinners by Hymenoptera has evolved independently at least three times: once in the small chrysidoid family Sclerogibbidae, the members of which are obligate ectoparasitoids of embiopteran nymphs (the females are ant-like and wingless and able to smoothly maneuver through the serpentine tunnels of their hosts) [41,42]; once in Sericobracon Shaw (Braconidae), in which one species (and possibly another) is an endoparasitoid of the clothodid Antipaluria urichi (Saussure) [43]; and at least once in the Scelionidae (genera Embidobia Ashmead, Palaeogryon Masner and Embioctonus Masner), which include egg endoparasitoids of webspinners [44][45][46]. The evolutionary path that led to the exploitation of webspinners in each of these wasp lineages is still unclear. Engel and Grimaldi [47] hypothesized that sclerogibbids were originally beetle parasitoids, although their abundance and diversity in Cretaceous amber may instead suggest that they had already exploited webspinners or related polyneopterans in the Mesozoic [48].
Parasitoids of webspinners within Diptera evolved only in the Tachinidae, the largest and most successful of all dipteran lineages of endoparasitoids. Recent reconstructions of the evolution of host preferences in this family suggest that the last common ancestor of tachinids likely developed on soil-dwelling invertebrates, and the clade later radiated and diversified on various phytophagous insect lineages (e.g., larval lepidopterans and coleopterans, and adult hemipterans) through a series of host shifts [29,49]. Sometimes host shifts involved distantly related and/or ecologically diverging host groups, e.g., Loewia Egger (and relatives) and Spilochaetosoma Smith apparently switched to chilopods and scorpions from lepidopteran-associated ancestors [28]. A sudden host spillover may best explain the parasitism of webspinners by species of the four distantly related tachinid genera discussed herein. Species of each of these genera exploited webspinners independently and presumably did so through a shift from a host that shared ecological characteristics and/or behavioral traits with them. Interestingly, these tachinids all practice an indirect oviposition strategy, i.e., they do not lay eggs directly on (or into) their host's body [34,50]. They instead follow visual and chemical cues to locate the microhabitat of the host and lay eggs in places where a host may pass by. These cues include food remains, shelters, odors or other environmental features that unveil the presence of a potential host [51]. This hunting strategy can lead to the chance parasitization of non-target insects that are occasionally repeatedly successful, giving rise to new host associations and trophic interactions. Embiopteran and lepidopteran larvae, although phylogenetically very far apart, both produce silky structures (e.g., tunnels, cases, cocoons), suggesting that this cue could be used by parasitoids to help locate them. Remarkably, most of tachinids specialized on webspinners appear to be grouped with taxa developing on Lepidoptera. For example, Phytomyptera species often attack concealed larvae of micromoths (e.g., Pterophoridae, Tineidae and Tortricidae) [28,29]. Phytomyptera woodi is the only known species of its genus with a non-lepidopteran host. Minthoini also include species developing on concealed larvae of Lepidoptera, however hosts are unknown for most of the species, hinting at possibly unusual hosts for many of them. Graphogastrines and minthoines lay membranous eggs ready to hatch, and the planidial larvae actively seek for hosts. Members of the Goniini reach their hosts in a different way. They lay tiny "microtype" eggs on the food of their hosts that are ingested by the feeding host. The eggs hatch in the gut and the first instar larvae migrate into the host haemocoel to complete development. As a rule, goniines parasitize phyllophagous caterpillars and, more rarely, sawfly larvae by laying their eggs along leaf margins, in particular those which have been chewed by hosts. To our knowledge, only a few goniines have switched to non-leaf feeders. These include several species of the genera Pexopsis Brauer & Bergenstamm and Erythrocera Robineau-Desvoidy, and the species Manola xenocera Richter and Masistyloides kononenkoi Richter, which all develop in adult beetles, Arama gobica Richter which develops in cockroaches [29], Ocytata pallipes (Fallén) which is a parasitoid of earwigs, and several species of Allophorocera Hendel which develop in crane fly larvae [29,52]. Despite the lack of detailed information about deposition strategies, these goniines presumably still lay their microtype eggs on the food of their nonleaf feeder hosts. What factors were involved in these shifts in deposition strategy is unknown. Even more of a mystery is the parasitization of wood-dwelling beetle larvae by members of the goniine genus Pseudalsomyia Mesnil [53] because the host larvae apparently do not leave their tunnels. This situation is the most comparable to that of the webspinner parasitoids of the goniine genera Perumyia and Embiophoneus, which also attack concealed, non-phyllophagous hosts that usually do not leave their shelters. The discovery of the trophic strategies of any of these aberrant goniines may shed light on the evolutionary path that has led to these bizarre host shifts in this megadiverse tribe.

Conclusions
Tachinids shifted to webspinners at least four times: twice in the huge tribe Goniini (Embiophoneus and Perumyia), probably once in the graphogastrine genus Phytomyptera, and once in the minthoine genus Rossimyiops. This specialization likely evolved in each lineage from ancestors sharing similar habits such as attacking silkprotected or concealed hosts or searching microhabitats like those occupied by webspinners.