Plecia schusteri Fitzgerald, 2021

Fitzgerald, Scott J., 2021, New species of Neotropical Plecia Wiedemann (Diptera: Bibionidae) and delineation of the americana-, nigra-, and xyele- species-groups, Zootaxa 5005 (1), pp. 21-40 : 33-36

Plecia schusteri Fitzgerald sp. n.

( Figs. 24–30 )

Type Material. Holotype: Male , point-pinned ( CNCI), “ GUATEMALA, Guatemala, Puerta Parada, 1840 m, 27 X–3 XI 2018, Col.: J.C. Schuster ” [white label] . HOLOTYPE, Plecia schusteri Fitzgerald [red label], terminalia dissected.

Description. Holotype Male. General coloration. Entirely black to very dark brown, except mesonotum mostly orange, but blackened anteromedially. Head. Three ocelli on tubercle. Antenna dark brown with seven bead-like flagellomeres, apical flagellomere minute, nipple-like. Compound eye holoptic with minute sparse ommatrichia, divided into upper and lower section of larger and smaller facets by slight depression. Face not produced anteriorly. Clypeus rectangular, about twice as long as wide. Clypeus + proboscis short, subequal to length of antennae. Palps brown, five-segmented. Thorax. Mesonotum with a subtle median and a pair of more distinctive dorsocentral grooves. Mesonotum largely bare with short dark sparse setae in median and dorsocentral grooves as well as laterally; much more numerous anteriorly. Katepisternum with patch of dorsal setae, anepimeron and metakatepisternum with a few setae. Legs. Slender, dark brown with dense short dark setae. Hind tibia nearly parallel-sided. Hind basitarsus long, slender, parallel-sided, approximately seven times as long as wide. Wing. About 7.0 mm, light brown fumose, darker anteriorly. All veins brown, anterior veins bolder, pterostigma dark brown and darker than the membrane. R 2+3 short, evenly curved, strongly divergent from R 4+5, ending in C. Abdomen. With short dark hair. Terminalia ( Figs. 25–30 ). Epandrium (tergite nine) rectangular, broader than long, nearly truncate posteriorly with a minute narrow median notch, though tergite is creased medially along entire length. Epandrium without posteromedian lobe or flap visible in dorsal view, but with a median keel on ventral surface visible in posterolateral view ( Fig. 28 ). Epandrial lobes apically rather truncate. Anterior margin of epandrium with slight broadly U-shaped excavation. Gonocoxites ventrally broader than long, with deep broad U-shaped posteromedian cleft; sclerotized median projection absent, but bottom of cleft broadly sloping into genital chamber and large membranous hump which can been seen in both posterior and ventral views. Lateral lobes of gonocoxites present, in ventral view inner (medial) surface sloping into genital chamber, in posterolateral view lobes broadly triangular though apically rounded. Gonostylus minute, in ventral view, pear-shaped ( Fig. 25 ), in posterior view rounded basally with a distinct thumb-like apical projection ( Fig. 29 ), and in posterolateral view rounded basally with a small thumb-like projection appearing much shorter than in posterior view ( Fig. 30 ).

Female. Unknown.

Diagnosis & Remarks. This species is most similar to P. americana Hardy and P. evansi Fitzgerald , but can be distinguished most easily by color differences: P. americana with thorax entirely orange (sometimes with some brown markings on thoracic pleurae), P. evansi with thorax entirely black, and P. schusteri with scutum black anteriorly and orange posteriorly, scutellum orange, thoracic pleurae and postnotum black. The male terminalia of these three species are very similar; all have strongly reduced gonostyli, gonocoxites with ventral posteromedian margin deeply cleft, posteromedian margin of epandrium with only small cleft, and lateral lobe of gonocoxites present with medial (inner surface) sloping into the genital chamber. P. evansi has a very broad, shallow, V-shaped epandrial cleft (cleft about ¼ depth of sclerite) with a small median lobe, while P. schusteri has only a narrow notch posteromedially. The terminalia of P. americana and P. schusteri differ most in the shape of the gonostylus; in posterior view, the gonostylus of P. americana is triangular apically while there is a distinct thumb-like apical development in P. schusteri (compare Figs. 29 & 31 ) and in posterolateral view the apex of the gonostylus of P. americana is very short and slightly hooked whereas that of P. schusteri is longer and more digitate (compare Figs. 30 & 32 ). P. schusteri belongs to the americana -species-group (see Discussion) and will key to couplet 28 using Hardy’s 1945 key.

Etymology. The specific epithet honors Dr. Jack Schuster (UVGC), collector of the holotype as well as the type series of several other recently described Guatemalan Diptera such as Amerikeroplatus dimorphicus Fitzgerald (Keroplatidae) and Ditomyia nana Fitzgerald (Ditomyiidae) .

Distribution. Known only from the holotype collected in Guatemala.

Figures

FIGURES 24–26. P. schusteri sp. n., holotype male. 24. Habitus, scale bar = ca. 1.0 mm. 25. Male terminalia, ventral, scale bar = ca. 0.5 mm. 26. Male terminalia, dorsal, scale bar = ca. 0.5 mm. Abbreviations: gc, gonocoxite; gs, gonostylus; llgc, lateral lobe of gonocoxite; t9, tergite nine.

FIGURES 27–32. Male terminalia. 27–30, P. schusteri sp. n., holotype. 27. Posterior. 28. Posterolateral. 29. Close up of gonostylus, posterior. 30. Close up of gonostylus, posterolateral. 31–32, P. americana Hardy. 31. Close up of gonostylus, posterior. 32. Close up of gonostylus, posterolateral (area behind tip of gonostylus lightened in order to make apex of gonostylus more visible). Scale bar = ca. 0.5 mm (Figs. 29–32 slightly enlarged, not to scale).Abbreviations: c, cerci; gc, gonocoxite; gs, gonostylus; i, inner (medial) surface of lateral lobe of gonocoxite; llgc, lateral lobe of gonocoxite; t9, tergite nine.