Macrostomus apicalis (Bezzi)

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 : 507-508

Macrostomus apicalis (Bezzi)

( Figs 1A–C )

Rhamphomyia apicalis Bezzi, 1909: 330 . Type locality: Peru, Pasco, Pichis River, Puerto de Yesup .

R. apicalis: Melander, 1928: 186 ; Collin, 1933: 211 (cit.).

Macrostomus apicalis: Smith, 1961: 53 ; 1967: 29 (cat.); Rafael & Cumming, 2004: 446; Yang et al. 2007: 145 (cat.).

Diagnosis. Female. Postpedicel short setulose; thorax shiny black; legs predominantly yellow; hind tibia with four longer dorsal setae; wing with apex slightly brown infuscate; anal lobe slightly narrower than cell cua; abdomen shiny black, gold pruinose.

Redescription. Holotype ♀ ( Fig. 1A ) (originally described as male). Body length 2.7 mm; wing length 2.8 mm. Head narrowly dichoptic. Inferior facets slightly larger than superior ones. Frons shiny brown slightly wider than anterior ocellus width, narrowing ventrally. One pair of proclinate ocellar setae. Face gray pruinose, slightly narrower than frons, narrower medially, slightly higher than frons. Postcranium shiny brown to black, slightly gray pruinose, except on postocular margin. Inner vertical seta stouter than outer vertical seta, latter subequal in length to uniseriate postocular row of setae; occipital setae slightly shorter than postoculars and restricted to dorsal half. Antenna with pedicel yellow to brown, postpedicel velvety dark brown to black, short setulose. Proboscis yellow, as long as head height. Thorax shiny black; pruinosity, depending on angle of light incidence, slightly more distinct on disc of scutum, scutellum and mediotergite. Thoracic chaetotaxy: setae somewhat damaged, 2–3 antepronotals weak; 1 postpronotal; dorsocentrals damaged (probably four); 1 presutural supra-alar; 0 postsutural supra-alar; 1 postalar; 1–2 proepisternals; 1 notopleural; scutellars damaged (probably two pairs); 2–3 laterotergitals. Legs ( Fig. 1A ) mainly yellow except apex of fore tibia, fore tarsomere 5, apex of mid tibia, distal mid tarsomeres, apex of hind femur, distal half of hind tibia and almost entire hind tarsus dark brown to black. Legs longer setae: mid tibia with 1 anteroventral and 1 posteroventral stouter; hind leg ( Fig. 1B ): hind femur with 1 anterior sub-basal, 1 anteroventral on distal third, both short but distinct; hind tibia with 4 longer dorsal setae with 1 at basal third and 3 on distal half; hind tarsomere 1 with 1 median dorsal seta. Wing ( Fig. 1C ) hyaline with apical margin slightly brown infuscated; pterostigma darker; anal lobe narrow; veins M 1, M 2 and CuA+CuP evanescent; distal section of vein M 4 longer than vein dm-m; cell dm somewhat truncate. Halter yellow. Abdomen brown to black, gold pruinose, with longer setae laterally. Sternites concolorous with tergites. Tergite and sternite 8 unmodified; cercus short (broken?).

Male. Unknown. The holotype specimen was originally described as male.

Geographical records. PERU [Pasco], Pichis River.

Type material examined. HOLOTYPE ♀. “ PERU [Pasco], Pichis [river], Puerto [de] Yessup [ Yesup ], xii.1903 ” [300 m] ( SNSD).

Holotype condition. Left antenna and left wing lost; right wing mounted on microslide with Canada balsam; thorax somewhat damaged by pin; abdomen in microvial with glycerin. Terminalia not dissected.

Remarks. Macrostomus apicalis was described from a single female specimen from Peru, Pichis River, Puerto de Yesup (SNSD, examined by JAR about 30 years ago). Since then, no additional conspecific specimens have been found in collections, so the redescription of this species is included here, with the original unpublished photos of the type specimen. Macrostomus apicalis is the last species of Macrostomus described by Bezzi (1905, 1909) not yet redescribed. Unfortunately, it is in poor condition and the genitalia was not studied and the association with male specimens from the type locality is necessary to facilitate the recognition of this species. The type specimen is externally remarkably similar with M. melanothorax (see below) and it will be necessary to study the female genitalia of the holotype of M. apicalis (unfortunately not drawn 30 years ago) to confirm a possible synonymy between both species.

+ CuP posterior branch of cubital vein; dm —discal medial cell; dm–m —discal medial crossvein; M 1 —first branch of media; M 2 —second branch of media; M 4 —fourth branch of media.

Figures

FIGURE 1. Macrostomus apicalis (Bezzi, 1909), holotype ♀. A. Habitus, lateral view (old photo obtained 30 years ago); B. Hind left leg, lateral view; C. Right wing. Scale bars, figures A–C = 1 mm.Abbreviations: CuA—anterior branch of cubital vein