Phyllomya Robineau-Desvoidy

Shima, Hiroshi, Zhang, Wenxia & Tachi, Takuji, 2022, A systematic study of Old World Phyllomya Robineau-Desvoidy (Diptera: Tachinidae), Zootaxa 5099 (4), pp. 401-449 : 403-404

Genus Phyllomya Robineau-Desvoidy

Phyllomya Robineau-Desvoidy, 1830: 213 . Type species: Musca volvulus Fabricius, 1794 , by monotypy.

Gibsonomyia Curran, 1925: 281 . Type species: Gibsonomyia nigricosta Curran, 1925 (= Morinia washingtoniana Bigot, 1889 ), by original designation.

Metopomintho Townsend, 1927: 283 . Type species: Metopomintho sauteri Townsend, 1927 , by original designation.

[For other synonyms, see Herting & Dely-Draskovits (1993: 387)]

Diagnosis. External adult morphology (male and female). Small to medium-sized (5–12 mm), slender, blackish flies; eye usually bare (rather densely haired in P. annularis ); ocellar seta developed, sometimes short, especially in female; parafacial sometimes haired; gena wide, at least 1/4 of eye height; face flattened, without facial carina; facial ridge with a few setae just above vibrissa; vibrissa inserted at level of lower margin of face; occiput weakly to well convex, with short, black setulae behind postocular setae and whitish pile ventrally; antennal pedicel with several short setae and a long seta (longer than pedicel); arista usually plumose, rarely pubescent; palpus rather slender, weakly clavate. Prosternum bare; proepisternum bare; 0–2 presutural and 0–3 postsutural acrostichal setae; 2–3 presutural and 2–3 postsutural dorsocentral setae; 0 presutural and 1–3 postsutural intra-alar setae; 3 postsutural supra-alar setae, posterior seta sometimes fine or missing; anepimeron with only short hairs; 2 or 3 katepisternal setae; anatergite bare; scutellum with 2–3 pairs of marginal setae, lateral setae absent; wing hyaline, at most weakly tinged with pale brown, rarely tinged with brown apically; tegula and basicosta black; costagial setae long and strong, at least one of them extending well beyond humeral vein ( Figs 1–2 ); base of vein R 4+5 with only a few fine setulae; vein M 1 gently curved and reaching wing margin separately from vein R 4+5; last section of vein CuA 1 at most as long as dm-cu crossvein; vein CuA 1 +A 1 not reaching wing margin; legs black; fore coxa bare on mid-ventral surface; hind coxa bare on posterodorsal margin; fore tibia with 1–2 posterior setae; mid tibia with 1–3 anterodorsal, 2 posterodorsal and 1 ventral setae; hind tibia with 2–3 preapical dorsal setae. Abdomen with median marginal setae on syntergite 1+2 to 3rd and 5th tergites: nearly cylindrical or fusiform; syntergite 1+2 not excavated to posterior margin; male 5th sternite with a V-shaped cleft, posterior lobe weakly rounded, angulated or strongly pointed on postero-interior corner.

Male terminalia. Sixth tergite entire, or narrowly separated into 2 hemitergites on mid-dorsal portion, separated from syntergosternite 7+8 ( Figs 4–7 ); 6th sternite asymmetrical, separated from syntergosternite 7+8 on right side and articulated with it on left side ( Fig. 4 ); surstylus elongate, parallel-sided or tapering to apex in lateral view; cerci flattened, elongate and tapering to apex, sometimes completely fused on basal portion of dorsal surface and suture obliterated; bacilliform sclerite expanded inwards on mid-ventral portion, forming a long triangle (see Fig. 3 ); hypandrial arms separated; pregonite flat, at most weakly produced; postgonite elongate, tapering to apex; basiphallus shorter than distiphallus; epiphallus long, tapering to apex; distiphallus elongate, flat and sclerotized on dorsal proximal portion, membranous on ventral portion with spinules, apical portion elongate and membranous.

Female terminalia (e.g., Figs 124–126 ). Short; 6th tergite entire, concave on mid-dorsal portion or separated into 2 hemitergites, with a row of strong marginal setae; 6th sternite quadrate, with setae or hairs on posterior portion; 7th tergite slightly shorter than 6th, separated into 2 hemitergites, usually with several hairs on marginal portion; 7th sternite shorter than 6th, usually with several setae on posterior portion; 8th tergite reduced to a short and rather tall hemitergite, fused ventrally with 8th sternite, sometimes also fused posteriorly with hypoproct, without hairs; 8th sternite long and rounded ventrally, with minute setulae; epiproct absent; cercus short, rounded marginally, with many hairs.

First instar larva ( Figs 127–156 ). Body translucent, nearly cylindrical, 0.8–1.1 mm in length; cephaloskeleton with labrum narrowed, curved ventrally and pointed at apex, mid-dorsal portion sometimes convex in lateral view, dorsal cornu short and rounded on posterior margin, ventral cornu truncated at posterior apex; lateral plate rather large, more or less trapezoid; 2nd thoracic segment with or without a row of spinules on posterodorsal margin; 1st abdominal segment bare, 2nd to 7th segments sometimes with several rows of posteroventral spinules, rarely with a few rows of anterodorsal spinules, 7th segment with or without posterodorsal rows of spinules.

Remarks. Phyllomya belongs to the subfamily Dexiinae , which is categorized mainly by the flattened pregonite and hinged phallus (male terminalia). The Old World species of Phyllomya have a pair of the bacilliform sclerites that are long and triangular.A similar character state is found in Tachinini of the subfamily Tachininae (e.g., Tschorsnig 1985) and Winthemiini of the subfamily Exoristinae ( Tschorsnig 1985; Shima 1996). However, their detailed structure differs among these two tribes, and it is possible that they developed independently in each. In the female terminalia, Phyllomya has short and rather high 8th abdominal hemitergites that are fused ventrally with the characteristically broad 8th sternite and sometimes posteriorly with the hypoproct. This arrangement is peculiar to the Dexiinae . The female terminalia of Voria are similar in general structure, but the ventral fusion of the 8th hemitergites with the 8th sternite is not found in that genus. Furthermore, the aedeagal structure of Voria is entirely different from that of Phyllomya .

Stireman et al. (2019) published a molecular phylogeny of the Tachinidae , treating a good number of tachinid species. In their phylogenetic analysis Phyllomya volvulus is sister to a clade including most voriine tribes, such as Dexiini , Rutiliini , Doleschallini , Sophiini, and many genera of Voriini , although some other voriines, including Myotrixini, Dufouriini , Eutherini , several genera of Voriini and others, are scattered in paraphyletic clades. The genus Phyllomya is peculiar in the female terminalia and in the shape of the bacilliform sclerite of the male terminalia as described above. These characteristics are difficult to interpret phylogenetically because the terminalia of dexiine genera have not been well studied. More morphological studies on the subfamily Dexiinae , including of larvae, are needed to reach an acceptable classification that bridges the gap in knowledge between the molecular phylogeny and morphology.

Figures

FIGURES 1–2. P. sichuana Shima & Zhang, sp. nov., arrows showing long costagial seta. 1. Left wing in dorsal view. 2. Same, detail of wing base.

FIGURES 3–7. Male terminalia of Phyllomya spp. 3. Epandrial structure of P. aristalis (Mesnil & Shima), ventral view; bs = bacilliform sclerite. 4. 6th tergite, 6th sternite and syntergosternite 7+8 of P. albipila Shima & Chao, lateral view. 5. 6th tergite and syntergosternite 7+8 of P. annularis (Villeneuve), dorsal view. 6. 5th sternite, 6th tergite and syntergosternite 7+8 of P. rufiventris Shima & Chao, lateral view. 7. Same, P. elegans Villeneuve. Scale bars: 0.1 mm.

FIGURES 121–126. Phylomya spp. 121–123. Adult habitus/male head, lateral view. 121–122. P. sichuana Shima & Zhang, sp. nov. 123. P. takanoi Mesnil. 124–126. Female terminalia, lateral view. 124. P. arctogena Shima & Tachi, sp. nov. 125. P. chaoi Shima & Zhang, sp. nov. 126. P. sichuana sp. nov.

FIGURES 127–138. First instar larva and cephaloskeleton of Phyllomya spp., lateral view. 127–128. P. annularis (Villeneuve). 129–130. P. arctogena Shima & Tachi, sp. nov. 131–132. P. aristalis (Mesnil & Shima). 133–134. P. chaoi Shima & Zhang, sp. nov. 135–136. P. gibsonomyioides Crosskey. 137–138. P. gymnops (Villeneuve).Abbreviations: T2 and T3 = thoracic segments 2 and 3. A1 to A7 = abdominal segments 1 to 7.

FIGURES 139–150. First instar larva and cephaloskeleton of Phyllomya spp., lateral view. 139–140. P. humilis Shima. 141– 142. P. japonica Mesnil. 143–144. P. nobilis Mesnil. 145–146. P. procera (Meigen). 147–148. P. rufiventris Shima & Chao. 149–150. P. sauteri (Townsend).

FIGURES 151–156. First instar larva and cephaloskeleton of Phyllomya spp., lateral view. 151–152. P. sichuana Shima & Zhang, sp. nov. 153–154. P. takanoi Mesnil. 155–156. P. volvulus (Fabricius).