Marbenia cinerea, 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 : 367-368

Marbenia cinerea , sp. nov.

( Figs 1–7 )

Diagnosis. Frons entirely yellow with sparse whitish pruinescence; first flagellomere dark yellow; ocellar tubercle the same color of frons; face pale brown with transverse furrow above middle and slightly protruded below furrow; wing slightly gray tinged with 1 transverse wide hyaline band at base of distal third and hyaline at base, veins yellow on basal half and brown apically; scutum dark brown with postpronotal lobe and postalar callus yellow, covered by silvery gray pruinescence; scutellum yellow.

Redescription. Holotype male. Body: 2.6 mm. Wing: 2.1 mm. Head ( Figs 2, 3 ). Frons entirely yellow, including ocellar triangle, mat, with sparse pale yellow pruinescence. Ocellar triangle not protuberant, ocellus yellow forming an equilateral triangle. Medial vertical setae almost twice length of lateral vertical and postocellar setae; postocellar setae slender, divergent; ocellar pair stronger than post-ocular seta, ocellar and fronto-orbital the same length. Face dark yellow to pale brown without spots, subshiny with very sparse whitish pruinescence, more slender than frons. Setae: lower fronto-orbital plate with short brown setulae extended from fronto-orbital seta to insertion of antenna; a pair of convergent pseudo-vibrissae weakly developed, inserted slightly toward medial portion of face at mid height of face; parafacial setae reasonably developed, extended from mid height of face, shorter on dorsal portion and distinctly elongate and strong toward buccal opening; face with 1 deep transverse furrow above middle and slightly protruded below furrow. Parafacial and gena with the same color of face; gena short and wholly setulose. Antenna: scape very short, brown; pedicel velvet black with some short dorsal and marginal setae; first flagellomere dark yellow, with parallel sides, about 2 times longer than wide, inflate; arista bipectinate, with 9 dorsal and 4 ventral branches with some interspersed very short branches. Buccal structures pale brown; labrum small with yellowish pruinescence; palpus short, ovate, setulose. Occiput brown with dorsal margin yellow, postgena pale brown. Compound eye with sparse short setulae between facets. Thorax ( Figs 1, 3 ). Scutum dark brown, paler on lateral margins, with postpronotal lobe and postalar callus yellow; silvery gray pruinescence; scutellum yellow. Setae: 2 postsutural dorsocentral; 2 notopleural; 1 postpronotal; 1 postsutural intra-alar; 1 postalar; all setae well developed; scutellum with one preapical and one sub-basal pairs long and strong. Pleura yellowish brown, with sparse yellowish pruinescence on some regions, clearer on posterior half (anepimeron, katepimeron, meron and laterotergite); 1 long katepisternal seta and some small setae on lower half of katepisternum; 1 slender propleural. Wing ( Fig. 4 ) yellowish tinged with apical, posterior margin and a transverse band gray. Legs short and robust; coxae and femora brown, fore and mid tibiae brown, hind tibia dark brown, all tibiae with a median ring and apices yellow, tarsomeres 1–3 whitish and 2–5 yellow. Fore femur with long robust setae on posteroventral margin; mid coxa with a comb of black strong setae on anterodistal margin; apicoventral spine of the mid tibia developed; mid tarsus with ventral yellow spines on tarsomeres 1–4. Abdomen pale brown; short, ovate, wider on segments 2–3; setae short; tergite 6 slightly longer than the remaining tergites. Terminalia ( Figs 5–7 ): epandrium low, shallowly concave; postgonites rather short, pointed apically, anvil-like in lateral view with base projected anteriorly; ejaculatory apodeme short and wide, basal process about half the length of ejaculatory apodeme; phallus wide and long, truncate apically; cerci small, rounded and widely fused medially.

Female: unknown.

Type material. Holotype ♂ ( USNM) labeled: “ ECUADOR. Prt. Orellana / Rio Tiputini (038.2' /S, 768.9 W), 12–20 Aug / 1999, W. N. Mathis, A / Baptista, M. Kotrba.

Distribution. Ecuador.

Etymology. From Latin cinis = ashes, referring to the gray pruinescence that covers the scutum of this species.

Remarks. Marbenia cinerea , sp. nov. is similar to M. pallida , sp. nov. in the coloration of the frons, which is entirely yellow, and the mostly yellow wing. Besides the characters given in the key and diagnosis, this species can be distinguished from M. pallida , sp. nov. by the following characters of the male genitalia: postgonites smaller, medial digitiform process absent, cerci medially fused and protuberant in lateral view and ejaculatory apodeme wide with elongated basal process.

Figures

FIGURES 1 – 4. Marbenia cinerea, sp. nov. (holotype): 1, habitus, lateral view; 2, head, frontal view; 3, dorsum of thorax; 4, left wing, dorsal view.

FIGURES 5 – 7. Marbenia cinerea, sp. nov., male terminalia (paratype): 5, posterodorsal view of epandrium and internal terminalia; 6, same, lateral view; 7, ejaculatory apodeme, lateral view. All figures in the same scale. Scale = 0.2 mm. Abbreviations: cerc, cercus; ep, epandrium; hypd + phall, hypandrium + phallapodeme; ph, phallus; pg, postgonite..