Macrostomus hyalopteryx, Rafael & Marques, 2021

Rafael, José Albertino & Marques, Dayse Willkenia A., 2021, Four new species of Macrostomus Wiedemann and a checklist of Empididae s. str (Diptera) from Peru, Zootaxa 4981 (3), pp. 506-530 : 520-521

Macrostomus hyalopteryx sp. nov.

( Figs 11A–L )

http://zoobank.org/ urn:lsid:zoobank.org:act:19FF4851-EC1E-448F-B3EE-D19993590595

Diagnosis. Male. Postcranium narrow. Thorax shiny black contrasting with legs mainly yellow; wing entirely hyaline; abdomen shiny black with blue reflection in certain angle of light incidence; tergite 8 with a stout short-rounded projection posteriorly; epandrium posterodorsal lobe with 2 short, stout spine-like setae distally.

Description. Holotype ♂ ( Fig. 11A ). Body length 2.7 mm; wing length 2.9 mm. Head narrowly dichoptic. Frons shiny black, slightly narrower than anterior ocellus width. One pair of proclinate ocellar setae. Face shiny black, as wider as frons width. Postcranium narrow, shiny black with inconspicuous gray pruinosity. Inner vertical seta stout; outer vertical seta apparently broken; postocular row of setae uniseriate; occipital setae slightly shorter than postoculars and restricted to dorsal half. Gena and postgena with 2 minute setae each. Antenna dark brown to black. Proboscis mainly yellow, darker basally, as long as head height. Palpus dark brown to black. Thorax ( Fig. 11A ) shiny black with gray pruinosity on level of scuto-scutellar suture, entire scutellum and on laterotergite. Mediotergite shiny black. Thoracic chaetotaxy: 3 antepronotals, 1 stout postpronotal, 2 tiny; 4 dorsocentrals; 1 supra-alar presutural; 1 supra-alar postsutural (broken); 1 postalar; 1–2 tiny proepisternals; 2 stouter notopleurals, 1 weaker; 2 pairs of scutellars; 4–5 laterotergitals. Legs ( Fig. 11A ) predominantly shiny yellow with ventral shiny black spot on all trochanters, extreme apices of all femora, distal half of fore and mid tibiae, distal 3/4 of hind tibia and all tarsi brown to black. Legs longer setae: Fore tibia with 1 dorsal at basal third, 1 ventral at apex; mid tibia with 1 anterodorsal and 1 posterodorsal at basal third, 1 ventral at apex; hind tibia with 5 longer dorsal setae with 1 at basal fourth, 2 submedian, 2 at distal forth, latter two setae stouter; hind tarsomere 1 with longer setae distally and 3–4 ventrally. Wing ( Fig. 11A ) entirely hyaline without brown infuscation. Veins M 1 and M 2 weaker; vein CuA+CuP evanescent; distal section of vein M 4 almost 3X longer than vein dm–m; cell dm somewhat shortened and truncate ( Fig. 11A ). Halter yellow. Abdomen ( Fig. 11B ) shiny black with blue reflection at certain angles. Tergites with posterior setae longer. Postabdomen shiny black. Tergite 8 ( Fig. 11D ) in dorsal view with stout, short-rounded projection posteriorly, with 4–5 longer setae surrounding and including projection, basally with inconspicuous basal sinus; in lateral view ( Figs 11C, F ) hat-shaped, with apex somewhat truncate and distal margin backward projected with distinct membranous connection with cercal bridge. Sternite 8 ( Figs 11C, E ) with wide basal sinus, without saddle-shaped protuberance and loosely connected posterolaterally with respective tergite. Epandrium ( Fig. 11F ) with longer setae posteriorly and posterodorsally; posterodorsal lobe higher than anterodorsal lobe, with 1 subapical and 1 apical short, stout seta; no transverse sclerite between anterodorsal lobe of epandrium and anterior cercus. Epandrium without anterodorsal cleft, with deep anteroventral cleft. Anterior cercus ( Figs 11G, H ) well sclerotized, upwardly directed, multilobate, with longer setae on distal half; in lateral view ( Fig. 11G ) with distinct acuminate projection posteriorly; in anterodorsal view ( Fig. 11H ) C-shaped, with stout medial process of anterior cercus. Median cercus ( Fig. 11G ) small, somewhat flattened, with dorsal and posterior uniseriate row of marginal setae. Posterior cercus ( Fig. 11G ) smaller than median cercus, somewhat membranous, with 2 longer marginal setae. Ventral projection of cercus ( Figs 11G, I ) wider and less sclerotized dorsally, stouter and projected ventrally, parallel sided to each other, with distinct posterior setae medially on more sclerotized area ( Fig. 11I ). Dorsal and ventral hypoproctal lobes ( Fig. 11I ) somewhat connected, both short setose. Hypandrium expanded laterally at connection point with epandrium ( Fig. 11K ); gonocoxal apodeme wide ( Fig. 11J ); hypandrium microsetulose posteriorly and posterior branch distinctly sinuose ( Fig. 11J , black arrow). Ejaculatory apodeme ( Fig. 11J ) trilamellar with ventral lamella reduced. Phallus same length as hypandrium.

Female. Unknown

Geographical records. Peru (Cuzco).

Type material examined. HOLOTYPE ♂, labelled: “ PERU, Cuzco, Ttio , 13º31′35.5″S – 70º53′55″W, 2000 m, 25.viii.2012 ” / “sweep, JA Rafael, RR Cavichioli, DM Takiya” / “ Holotype ♂, Macrostomus hyalopteryx Rafael & Marques ” ( Fig. 11L ) ( MUSM).

Holotype condition. Pinned, double mounted. Right wing lost. Abdomen dissected, stored in microvial with glycerin.

Etymology. From the Greek hyalos = hyaline, transparent and pteryx = wing, which refers to the wing entirely hyaline.

Remarks. Characters allowing a well-founded species-group placement are presently not available for M. hyalopteryx sp. nov. It appears to be related to M. trilineatus Rafael & Marques, 2019 , described from Bolivia, as both species share the narrow postcranium, shape of male tergite 8 with short projection distally, with apex rounded and when seen in lateral view with distinct ventral keel connected to cercal bridge, multilobate anterior cercus, epandrium with stout setae distally and by the ventral projection of the cercus projected ventrally, each branch parallel sided to each other, with distinct posterior setae medially. It differs by the thorax entirely shiny black (versus thorax shiny yellow with three longitudinal black stripes on mesonotum in M. trilineatus ), wing entirely hyaline (versus wing light brown infuscate along costal margin, darker at pterostigma), abdomen shiny black with blue reflection at certain angles (versus abdomen shiny black, except basal sternites yellow, without blue reflection), epandrium posterodorsal lobe with two short, stout setae distally (versus posterodorsal lobe with two stouter, spatulate apical spine–like setae besides other slender setae). At a glance, this species is somewhat similar to species of Porphyrochroa Melander by the abdominal blue reflection and short cell dm. However, it presents all other defining characters of Macrostomus species.

Figures

FIGURE 11. Macrostomus hyalopteryx sp. nov., holotype ♂. A. Habitus, lateral view; B. Abdomen, dorsal view; C. Apex of abdomen, lateral view; D. Tergite 8, dorsal view; E. Sternite 8, ventral view; F. Epandrium detached, lateral view; G. Cerci lobes and hypandrium, lateral view; H. Anterior cercus, anterodorsal view; I. Anterior cercus, subepandrial sclerite and ventral process of cercus, anterior view; J. Hypandrium and phallus, lateral view (black arrow indicating sinuose posterior branch of hypandrium); K. Hypandrium, posterior view; L. Holotype labels. Scale bars, figures A = 1 mm; B = 0.5 mm; C–K = 0.2 mm. Abbreviations: a ce, anterior cercus; c brd, cercal bridge; hypd, hypandrium; goncx apod, gonocoxal apodeme; m ce, median cercus; mpac, mesial process of anterior cercus; p ce, posterior cercus; ph, phallus; sbepand scl, subepandrial sclerite; st, sternite; t, tergite, vpc, ventral process of cerci.