Macrostomus trifidus, Rafael & Marques, 2019

Rafael, José Albertino & Marques, Dayse Willkenia Almeida, 2019, Five new species of Macrostomus Wiedemann and a checklist of Empididae (s. str.) (Diptera) from Bolivia, Zootaxa 4567 (2), pp. 251-275: 267-269

publication ID

https://doi.org/10.11646/zootaxa.4567.2.3

publication LSID

lsid:zoobank.org:pub:76FF8984-7ABC-4751-8FA9-943501F9D63A

persistent identifier

http://treatment.plazi.org/id/809DA5CB-62C5-4153-873D-8097436197E1

taxon LSID

lsid:zoobank.org:act:809DA5CB-62C5-4153-873D-8097436197E1

treatment provided by

Plazi

scientific name

Macrostomus trifidus
status

sp. nov.

Macrostomus trifidus   sp. nov.

( Figs 11 View FIGURE 11 A–O, 12A–E)

urn:lsid:zoobank.org:act:809DA5CB-62C5-4153-873D-8097436197E1

Diagnosis. Thorax shiny yellow with scutellum and mediotergite brown, gray-yellow pruinosity denser on disc of scutum and on scutellum. Wing brown, infuscation darker along costal and r 1 cells and apex of cell r 2+3. Tergite 8 elongate distally, basally more sclerotized with a sclerotized protuberance at base of the projection connecting with mesial cercal bridge of anterior cercus. Sternite 8 with shallow basal medial sinus, with saddle-shaped posterodorsal protuberance. Epandrium with longer setae posteriorly and mainly on posterior lobe. Anterior cercus multilobate, with few longer setae posterodorsally; posterior cercus trifid, all branch yellowish, inwardly curved; ventral projection of cercus downwardly directed, horizontally placed distally when viewed anteriorly or posteriorly, glabrous and not touching each other. Hypandrium well sclerotized, same width throughout, with a hook distally.

Description. Holotype ♂ ( Fig. 11A View FIGURE 11 ). Body length 3.3 mm; wing length 3.8 mm. Head narrowly dichoptic. Frons shiny black, slightly narrower than anterior ocellus width. One pair of proclinate ocellar setae. Face slightly narrower than frons width. Postcranium shiny black, entirely and sparsely gray pruinose. Inner vertical seta stouter than outer vertical seta, latter subequal in length to uniseriate postocular row of setae; 2 pairs of dorsal occipital setae. Gena with 2 setae and postgena with 1 weak seta. Antenna velvety black with postpedicel short pubescent. Proboscis dark brown with median third yellow and apical 2/3 of labellum yellow. Palpus black. Thorax shiny yellow with scutellum and mediotergite brown; scutum gray-yellow pruinose posteriorly and on scutellum. Thoracic chaetotaxy: 3 antepronotals; 1 postpronotal stout and 2 minutes; 3–4 dorsocentral setae; 1 presutural supra-alar; 0 postsutural supra-alar; 1 postalar; 4 proepisternals weak; 1 notopleural stout, 1 weak; 2 pairs of scutellars, the outer pair weaker; 4 laterotergitals. Legs shiny yellow with apex of fore and mid tarsi, distal 1/3 of hind femur, entire hind tibia and tarsus brown to black. Hind femur slightly clavate. Legs longer setae: hind femur with 1 slightly stouter anteroventral seta; hind tibia with 5 longer dorsal setae being with one at basal fourth, one near middle and three along distal third; hind tarsomere 1 with 1 longer median dorsal seta. Wing ( Fig. 11A View FIGURE 11 ) brown infuscated, darker along costal and r 1 cells and apex of cell r 2+3. Veins M 1, M 2 and CuA+CuP weakly evanescent distally. Last section of vein M 4 slightly longer than posterior length of elongate and blunt cell dm. Anal lobe very narrow. Halter light yellow. Abdomen shiny black. Tergite 1–2 with longer setae posteriorly. Tergite 8 in lateral view ( Figs 11B, D View FIGURE 11 ) curved, with sclerotized protuberance at base of projection connecting with mesial cercal bridge of anterior cercus; in dorsal view ( Fig. 11C View FIGURE 11 ) distally with elongate projection (setae broken on projection); basally more sclerotized with deep basal cleft. Sternite 8 ( Figs 11D, E View FIGURE 11 ) with shallow basal medial sinus, with saddle-shaped posterodorsal protuberance. Tergite 8 and sternite 8 strongly connected anteriorly. Epandrium ( Figs 11F, G View FIGURE 11 ) with very small anterodorsal excision and very small anteroventral excision; longer setae posteriorly and mainly on posterior lobe; anterior and posterior lobes of same length; epandrium in posterior view ( Fig. 11G View FIGURE 11 ) with stout protuberance mesially and several yellow distal short setae posterodorsally. Anterior cercus well sclerotized, upwardly directed, multilobate, with few longer setae posterodorsally; when viewed anteriorly ( Figs 11H, K View FIGURE 11 ) cercal bridge V-shaped, fused medially and ventrally. Median cercus ( Fig. 11I View FIGURE 11 ) inverted C-shaped, with elongate setae, less sclerotized distally. Posterior cercus ( Fig. 11J View FIGURE 11 ) trifid, all branches yellow, inwardly curved, apical two setose. Ventral projection of cercus ( Fig. 11K View FIGURE 11 ) downwardly directed, horizontally placed distally when viewed anteriorly or posteriorly, glabrous and not touching each other. Dorsal lobe of hypoproct ( Fig. 11K View FIGURE 11 ) larger with longer setae than narrower ventral lobe. Hypandrium ( Figs 11M, N View FIGURE 11 ) well sclerotized, same width throughout, with hook distally, longer setae restricted to posterior median third. Ejaculatory apodeme ( Fig. 11M View FIGURE 11 ) tetralamellar, all lamella subequal. Phallus ( Figs 11M, N View FIGURE 11 ) slightly longer than hypandrium.

Female. Body length 4.1 mm; wing length 3.8 mm. Frons slightly wider than anterior ocellus width. Face narrower than frons width. Wing slightly darker and wider ( Fig. 12A View FIGURE 12 ). Tergite 8 ( Figs 12B, C View FIGURE 12 ) with shallow basal and deeper distal sinus. Sternite 8 ( Figs 12B, D View FIGURE 12 ) with distinct protuberance ventrally; in ventral view with less sclerotized mid-longitudinal stripe from base to middle. Genital fork ( Fig. 12E View FIGURE 12 ) thin, elongated, bifid at apex. Genital chamber membranous.

Geographical records. Bolivia (La Paz).

Type material examined. HOLOTYPE   ♂, paratype ♀, on same pin: “ BOLIVIA, La Paz, Rio Beni, San Buenaventura, 270 m ”; “in copula, San Buenaventura , 22.iv. [19]79”; “QR code: NHMUK 010864590 View Materials ”; “ Holotype ♂ Paratype ♀ Macrostomus trifidus Rafael & Marques   ” ( Fig. 11O View FIGURE 11 ) (NHMUK).

Holotype condition. Good, pinned, double mounted, abdomen dissected, in microvial with glycerin.

Etymology. From the Latin tri = three and - fid = suffix denoting division, which refers to the three digitiform branch of posterior cercus.

Remarks. Characters allowing a well-founded placement are presently not available for M. trifidus   sp. nov. It differs remarkably from other known Macrostomus   species by the epandrium emitting mesially and porterodorsally a stout protuberance with several distal short setae; by the posterior cercus trifid with each branch digitiform and by the cercal bridge of anterior cercus V-shaped, fused medially and ventrally.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Empididae

Genus

Macrostomus