Marbenia pallida, Ale-Rocha, Rosaly, Freitas, Geovânia & Mathis, Wayne N., 2014

Ale-Rocha, Rosaly, Freitas, Geovânia & Mathis, Wayne N., 2014, Revision of the Neotropical genus Marbenia Malloch (Diptera: Periscelididae), Zootaxa 3872 (4), pp. 365-375 : 369-372

Marbenia pallida , sp. nov.

( Figs 8–15 )

Diagnosis. Frons pale yellow with whitish pruinescence; first flagellomere yellow; ocellar tubercle brownish; face, parafacial and gena yellow, face with two transversal grooves in the middle, with a transverse protuberance between them and a shallow rounded protuberance below antennae; wing yellowish tinged with apical, posterior margin and a transverse medial band gray; scutum covered with dense pale gold pruinescence; scutellum yellow.

Description. Holotype male. Body: 2.9 mm. Wing: 2.5 mm. Head ( Figs 9, 10 ). Frons pale yellow with whitish pruinescence. Ocellar triangle brownish, not protuberant; ocelli yellow forming an equilateral triangle. Medial vertical setae longer than lateral vertical setae, and fronto-orbital seta with intermediary length; post-ocellar setae developed and divergent; ocellar pair the same length of fronto-orbital setae. Face pale yellow with whitish yellow pruinescence above rounded protuberance and on lower lateral margins, slender than the frons, medial portion shiny; parafacial and gena yellow with whitish yellow pruinescence. Setae: lower fronto-orbit with short pale brown setae extended from fronto-orbital setae to insertion of antennae; a pair of developed convergent pseudovibrissae inserted on medial portion of face, below the transverse protrusion; parafacial setae well developed, extended from mid length of face, shorter on upper portion and increasing in length toward buccal opening; face with two transverse grooves in the middle and one transverse protuberance between them and a shallow rounded protuberance below antennae. Parafacial and gena yellow covered by dense whitish pruinescence; gena short and wholly setulose. Antenna: scape very short, black; pedicel black with some short dorsal and marginal setae; first flagellomere yellow, ovate, about 2 times longer than wide; arista bipectinate, with 11 dorsal and 4 ventral branches, and some interspersed very short branches. Buccal structures pale brown to yellow; labrum small with whitish pruinescence; palpus short, ovate, setulose. Occiput yellow; postgena yellow. Compound eye with sparse short setulae between facets. Thorax ( Figs 8, 10 ). Scutum pale brown with postpronotal lobe and postalar callus yellow, covered by dense pale gold pruinescence; scutellum yellow. Setae: 2 postsutural dorsocentral; 2 notopleural; 1 postpronotal; 1 postsutural intra-alar; 1 post-alar; all setae well developed; scutellum with one preapical and one sub-basal pairs long. Pleura pale brown with clearer margins, sparse silvery gray pruinescence on some regions; 2 long katepisternal setae and some small setae between them and on lower half of katepisternum; 1 slender propleural. Wing ( Fig. 11 ) yellowish tinged with apical, posterior margin and a transverse band gray. Legs short, robust, brown with all tarsomeres whitish yellow and tibiae with a median ring and apices yellow; fore femur with long robust setae on posteroventral margin; mid coxa with distal pale brown slender setae; apicoventral spine of mid tibia developed; mid tarsus with ventral black spines on tarsomeres 2–4. Abdomen pale brown, short, ovate, wider on segments 2–3; setae short; tergite 6 slightly longer than the remaining tergites. Terminalia ( Figs. 12–14 ): epandrium high, deeply concave; postgonites elongate with medial and lateral lobes, lateral lobe bearing a digitiform process; ejaculatory apodeme elongate and narrow, basal process of length of ejaculatory apodeme; phallus wide and pointed apically; cercus quadrangular in posterior view.

Female. As in male except transverse gray band in the middle of wing complete. Terminalia ( Fig. 15 ): syntergosternite 7 narrow, slightly sclerotized; sternite 8 narrow and shallowly concave on posterior margin; tergite 8 as a slender semi-arc; cercus small.

Type material. Holotype ♂ ( USNM) labeled: “ ECUADOR. Orellana / Res. Etnica Waorani / (039.4'S, 7627.2' / W; 216m, lot# 1420) / 1 Oct 1996, T. L. Erwin. Condition of type: good, not dissected. Paratypes. ECUADOR, Orellana: Res. Etnica Waorani (039.4'S, 7627.2'W; 216m, lot# 712), 21 Jun 1994, T. L. Erwin (1♂; INPA); (039.4'S, 7627.2'W; 216m, lot# 1459), 7 Feb 1996, T. L. Erwin (1♀; INPA); (039.4'S, 7627.2'W; 216m, lot# 1420), 1 Oct 1996, T. L. Erwin (2♀; USNM).

Distribution. Ecuador (Orellana).

Etymology. From Latin pallidus = ashen, referring to the generally pale coloration of this species. Remarks. This species is similar to M. cinerea , sp. nov. It can be easily distinguished from that species by the characters given in the key and diagnosis and characters of the male genitalia (see discussion under Remarks for M. cinerea ).

Figures

FIGURES 8 – 11. Marbenia pallida, sp. nov.: 8, habitus, lateral view; 9, head, frontal view; 10, dorsum of thorax; 11, left wing, dorsal view.

FIGURES 12 – 15. Marbenia pallida, sp. nov.: 4 – 6, male terminalia (paratype): 12, posterodorsal view of epandrium and internal terminalia; 13, same, lateral view; 14, ejaculatory apodeme, lateral view. 15, Female terminalia: posteroventral view. All figures in the same scale. Scale = 0.3 mm. Abbreviations: cerc, cercus; ST, sternite; TG, tergite.