Macrostomus contortus, 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 : 509-511

Macrostomus contortus sp. nov.

( Figs 3A–N )

http://zoobank.org/ urn:lsid:zoobank.org:act:10A5A05A-A455-465A-AD22-AA91E9B6F455

Diagnosis. Male. Postcranium with upper postocular third shiny with no pruinescence; thorax, legs and abdomen mainly shiny yellow; mid femur slightly clavate; hind femur distinctly crooked (sinuose) medially, with denser short, stout dorsal and ventral setae at curved area; tergite 8 subrectangular, with wide posterior sinus; epandrium with anterodorsal and posterodorsal lobes of equal height; posterior cercus sickle-shaped, upwardly directed.

Description. Holotype male ( Fig. 3A ). Body length 3.0 mm; wing length 3.3 mm. Head dichoptic. Frons shiny black, narrower than anterior ocellus width, narrowing ventrally. One pair of proclinate ocellar setae. Face as wide as frons ventrally, less shiny black than frons, slightly gray pruinose. Postcranium shiny black, sparsely gray pruinose, except upper postocular third with no pruinescence. Inner vertical seta stouter than ocellar and outer vertical setae, latter subequal in length to uniseriate postocular row of setae. Gena with 2–3 setae and postgena with no distinct seta. Antenna velvety black with postpedicel short setulose. Proboscis mainly yellow. Palpus brown to black. Thorax ( Figs 3A, B ) shiny yellow, yellow brown pruinose mainly on postpronotal and postalar calli, and on scutellum. Thoracic chaetotaxy: 5 antepronotals; 1 postpronotal stout and 1–2 minute; 4 dorsocentrals, with posterior pair stouter; 1 presutural supra-alar; 0 postsutural supra-alar; 1 postalar stout, 1 minute; 2 proepisternals; 1 notopleural stout, 1 weaker and 1 minute; 3 pairs of scutellars, outer pair weaker; 4 laterotergitals, ventral one weaker. Legs ( Figs 3A, C ) shiny yellow with apex of hind femur and apex of hind tibia black; fore and mid tarsi brown, hind tarsus black. Mid femur slightly clavate when seen in dorsal view, with short posteroventral row of spines at distal third. Hind femur ( Fig. 3C ) distinctly crooked (sinuose), with dense patch of short, stout dorsal and ventral setae at curved area. Hind tibia with 4 slender dorsal setae along entire length. Hind tarsomere 1 with 3 longer dorsal setae. Wing ( Figs 3A, B ) brown infuscate along costal cell and apices of cells r 1 and r 2+3. Veins M 1, M 2 and CuA+CuP evanescent. Distal section of vein M 4 longer than vein dm–m length. Cell dm with apex variable, right wing somewhat projected ( Fig. 3A ), left wing somewhat truncate ( Fig. 3B ). Halter light brown. Abdomen shiny yellow. Tergite 8 ( Fig. 3E ) subrectangular, with shallow basal sinus and wide distal sinus. Sternite 8 ( Fig. 3F ) with deep U-shaped basal sinus, without distinct posterolateral saddle-shaped projection. Tergite and sternite 8 ( Fig. 3G ) narrowly articulated. Epandrium ( Fig. 3H ) without anterodorsal cleft, neither anteroventral cleft, anterodorsal and posterodorsal lobes of same height. Anterior cercus ( Figs 3I, J ) subrectangular with posterodorsal angle slightly acute, inward curved ( Fig. 3I ). Cercal bridge emarginate dorsally and ventrally ( Fig. 3J ). Median cercus ( Fig. 3I ) narrow, somewhat flattened, with slender marginal setae. Posterior cercus ( Fig. 3I ) wider basally, with two small setae on basal lateral expansion, apex upwardly directed, simple, acuminate distally. Ventral projection of cercus with distinct lobe bearing 4–5 setae, fused medially forming weakly sclerotized plate ( Fig. 3K ). Dorsal hypoproctal lobe large, setulose ( Fig. 3K ); ventral hypoproctal lobe small, inconspicuous. Hypandrium ( Figs 3L, M ) slightly wider distally in lateral view, with five posterior setae (broken) and apex backward curved; posterior margin forming keel ending in laterally expanded flattened apex in posterior view ( Fig. 3M ). Ejaculatory apodeme ( Fig. 3L ) with dorsal lamella noticeably short. Phallus as long as hypandrium.

Female. Unknown.

Geographical records. Peru (Cuzco).

Type Material examined. HOLOTYPE ♂, labelled: “ PERU, Cusco, Quincemil, Pte [ Puente ] La Cigarra , 13º08′27″S – 70º23′14″W, 350 m ” / “ 01.ix.2012, sweep, JA Rafael, RR Cavichioli” / “ Holotype ♂ Macrostomus contortus Rafael & Marques ” ( Fig. 3N ) ( MUSM).

Holotype condition. Pinned, in good condition; abdomen dissected.

Etymology. From Latin contortus = crooked, sinuose, in reference to the shape of the hind femur.

Remarks. Macrostomus contortus sp. nov. appears closely related to M. falcatus Rafael & Marques, 2019 described from Bolivia, by tergite 8 subrectangular, posterior cercus sickle-shaped upwardly directed and ejaculatory apodeme with very short dorsal lamella. It differs by thorax shiny yellow (versus shiny black in M. falcatus ), hind femur distinctly crooked medially (versus straight), tergite 8 with deep distal sinus (versus no distal sinus), cercal bridge small, somewhat flat, not upward directed (versus upward directed, L-shaped), apex of hypandrium well sclerotized (versus apex somewhat membranous). It runs to couplet 1 of M. albicaudatus Rafael & Cumming, 2015 in the key presented by Rafael & Cumming (2015), by the yellow thorax, but it differs by tergite 8 with deep distal sinus (versus shallow distal sinus in M. albicaudatus ), posterodorsal lobe of epandrium as high as anterodorsal lobe (versus posterodorsal lobe higher).

Figures

FIGURE 3. Macrostomus contortus sp. nov., holotype ♂. A. Habitus, lateral view before abdomen dissected; B. idem, dorsal view; C. Right hind leg; D. Apex of abdomen, lateral view; E. Tergite 8, dorsal view; F. Sternite 8, ventral view; G. Tergite 8 and sternite 8, lateral view; H. Epandrium detached, lateral view; I. Cerci lobes, lateral view; J. Cercal bridge of anterior cercus and subepandrial sclerite, anterior view; K. Dorsal hypoproctal lobe, postero-mesial process of anterior cercus and ventral process of cercus; L. Hypandrium and phallus, lateral view; M. Hypandrium, posterior view (alveoli highlighted); N. Holotype labels. Scale bars, figures A–C = 1 mm; D–G, I–L = 0.2 mm; H, M = 0.1 mm.Abbreviations: a ce, anterior cercus; c brd, cercal bridge; d hyprct l, dorsal hypoproctal lobe; m ce, median cercus; p ce, posterior cercus; sbepand scl, subepandrial sclerite; st, sternite; t, tergite; vpc, ventral process of cerci.