Pachyrrhiza Philippi

Irwin, Michael E. & Winterton, Shaun L., 2021, Revision of the Patagonian stiletto fly genus Pachyrrhiza Philippi (Therevidae Agapophytinae), Zootaxa 4975 (2), pp. 273-305 : 275-276

Pachyrrhiza Philippi

Pachyrrhiza Philippi, 1865: 703 — Bigot (1890: 323) [misspelled as Pachyrriza; key]; Williston (1908: 207) [misspelled as Pachyrhiza]; Kertész (1909: 167) [synonym of Baryphora Loew ]; Kröber (1911: 489), (1913: 24) [synonym of Dialineura Rondani ], (1924: 7) [synonym of Tabuda Walker ]; Malloch (1932: 238) [key]; Oldroyd (1968: 382); Winterton (2006: 18), Gaimari & Webb (2009: 639) [key]; Webb et al. (2013: 15); Winterton et al. (2016); Irwin & Winterton (2020: 276).

Type species. Pachyrrhiza pictipennis Philippi, 1865: 704 , by monotypy.

Diagnosis. Male frons narrower than anterior ocellus at narrowest point; male occiput concave with single row of postocular macrosetae; both sexes with scape bulbous, longer than flagellum, with numerous large, erect macrosetae; flagellum turbinate; parafacial setae present as small patch of dark setae ventrally; femora all subequal in length, lacking velutum patches, hind femur with one or more anteroventral macrosetae; scutellum with two pairs of macrosetae; wing cell m 3 open; male gonocoxites lacking velutum or medial atrium; female with three spermathecae present.

Description. Head relatively broad, slightly wider than thorax, and much wider than high in anterior view; male frons narrower than anterior ocellus at narrowest point, slightly produced anteriorly, female frons flat; occiput concave (male), or convex (female); male with single row of postocular macrosetae dorsally, female with multiple rows; parafacial setae present only as small patch of dark setae adjacent to gena (absent in female P. argentoides sp. n.); genal setae white; palpus narrow apically; antenna length equal to, or longer than head length; scape bulbous, thicker than pedicel and flagellum, with numerous stout, erect macrosetae; flagellum shape turbinate, abruptly tapered. Thorax with scutum covered with erect filiform setae, often of variable length, denser anteriorly and longer in male; central depression of prosternum usually with setal pile, sometimes absent; pleuron dark, overlain with silver-grey pubescence; metanepisternum with postspiracular setae absent; scutellum shape rounded in profile; fore- and hind femoral velutum patches absent; femora all subequal in length; hind femur with 1–6 (rarely more) anteroventral (av) setae, either subapically (1–2) or along entire length as series (3–6 or more); posterior surface of midcoxa with or without setae; scutal chaetotaxy (pairs of macrosetae) notopleural, 3–5; supra alar, 1; post alar, 1; dorsocentral, 4–5, scutellar, 2; wing hyaline to extensively infuscate, mottled and fenestrate; wing cell m 3 open; vein R 2+3 shape smoothly sigmoid curved to wing margin. Abdomen acutely tapered; tergite 2 with a concentrated patch of shortened setae posteromedially or all setae uniform and regular in length; male frequently with extensive silver velutinous pubescence. Male genitalia ( Fig. 32A–E ) with gonocoxite with outer gonocoxal process present; velutum patch absent, posteromedial margins proximal so that medial atrium is absent; inner gonocoxal process present and articulated; hypandrium triangular; ventral lobe elongate and rounded apically; aedeagus with dorsal apodeme of parameral sheath subtriangular, distiphallus straight, relatively short, narrow distally (rarely wide); lateral ejaculatory apodeme relatively large and elongate. Female genitalia ( Fig. 32F ) with furca relatively large and sclerotised; three spermathecae, ducts joining to spermathecal sac duct near furca; spermathecal sac round, relatively small; female acanthophorite macrosetae with two sets present (A1 & A2); A1 enlarged, female sternite 8 posterior margin emarginate posteromedially.

Included species. Pachyrrhiza argentata Oldroyd, 1968: 383 , P. argentatoides sp. n.; P. elegantissima sp. n.; P. parargentata sp. n.; P. pictipennis Philippi, 1865 ; P. subpictipennis sp. n.

Comments. Compared to other South American therevid genera Pachyrrhiza has a surprisingly limited distribution throughout central Chile and adjacent Argentinian provinces ( Fig. 35 ). South American agapophytine therevids are almost completely restricted to the southern and western Patagonian Region, which may reflect their close phylogenetic connection to Australasian genera where the greatest diversity and species-richness is found in semiarid, subtropical to temperate regions, especially in Mediterranean-type climates. Pachyrrhiza is similarly restricted to semi-arid to Mediterranean habitats in the western Patagonian region. South American genera in subfamilies Therevinae and Phycusinae have much wider distributions throughout South America northwards into Central and North America. Pachyrrhiza argentata and P. pictipennis are the most commonly encountered species of the genus, although their respective distributions are relatively limited and apparently overlap very little. The remaining four species are found in similar habitats and are more locally distributed in the same region of central Chile and western Argentina.

Pachyrrhiza is a distinctive genus recognisable by the enlarged and bulbous antennal scape, narrow male frons, two pairs of scutellar macrosetae, parafacial with small patch of dark setae (absent in female of some species), single row of postocular macrosetae in the male and at least one large anteroventral macroseta on the hind femur. It is closely related to Sigalopella Irwin & Winterton , and these genera along with Entesia and Melanothereva form a monophyletic group (i.e., Entesia genus group, sensu Winterton et al. 2016) sister to the Taenogera genus group found in Australia, New Zealand and New Caledonia ( Winterton et al. 1999b; Winterton et al. 2016; Irwin et al. 2020). The key to genera of South American Agapophytinae by Irwin & Winterton (2020) can be used to identify individuals of Pachyrrhiza .

Figures

FIGURE 32. Pachyrrhiza pictipennis Philippi, 1865, male genitalia. A. epandrium; B. gonocoxites, ventral view; C. same, lateral view; D. aedeagus, lateral view; E. same, dorsal view. Female genitalia. F. Furca and internal genitalic structures. Scale line: 0.2 mm. Abbreviations: ag, accessory gland; d, distiphallus; da, dorsal apodeme of parameral sheath; ea, ejaculatory apodeme; f, furca; ga, gonocoxal apodeme; gs, gonostylus; hy, hypandrium; igp, inner gonocoxal process; lea, lateral ejaculatory apodeme; s, spermatheca; sd, spermathecal duct; ss, spermathecal sac; ssd, spermathecal sac duct; va, ventral apodeme of parameral sheath; vl, ventral lobe.

FIGURE 35. Distribution of Pachyrrhiza species in Chile and Argentina.