Microcerella desertum Santos, Mello-Patiu, Couri & Mulieri, 2025, sp. nov.

Microcerella desertum sp. nov. urn:lsid:zoobank.org:act: 6A42AA93-EAA7-433A-8CA7-EF8F720015F8 Figs 3–4 Diagnosis Male: head with 1 proclinate orbital seta; wings with vein R 1 bare or with 1–2 setae; terminalia with epandrium orange (Fig. 4D), basiphallus and distiphallus distinctly separated by a dorsal membranous strip (Fig. 3D), and vesica with a superior and inferior projection, the superior one bifurcated in ventral view and the inferior one with a pointed projection (Fig. 3D–E). Etymology The species epithet ‘ desertum ’, treated as a noun in apposition, refers to the Atacama Desert, the type locality of the new species. Type material Holotype CHILE • ♂, terminalia dissected and glued to a small piece of cardboard pinned under the specimen; “Chile, Atacama Prov. [Province] / 8 km N. Estancia Cas- / tilla, 30.VI.1966 / Mike E. Irwin & / Nelson Hitchins O. / Cal. Acad. Sci. Coll. [printed on white paper] // HOLOTYPE [printed on red paper] // Microcerella desertum sp. nov. / Santos, Mello-Patiu, / Couri & Mulieri 2025 [handwritten on white paper] // CASENT / 8451925 [printed on white paper]”; CASENT8451925; CAS. Paratypes CHILE • 1 ♂, with left fore and mid leg glued to a small piece of cardboard and exposed terminalia; same data as for holotype; MNRJ • 1 ♂, with left fore and mid leg glued to a small piece of cardboard, right foreleg lost and abdomen dissected and stored in a microvial with glycerin pinned under the specimen; same data as for holotype; CASENT 8451940; CAS. Description Male (n = 3) MEASUREMENTS. Length: 6–8 mm. HEAD. Parafacial, fronto-orbital plate and postocular orbit dark brown with silvery pruinosity (Fig. 4A– C); facial ridge with setae on lower quarter; parafacial with sparse setulae close to eye, 2 similar in size to subvibrissal setae; frons about 0.36–0.38x head width at level of ocellar triangle; frontal vitta blackish (Fig. 4C); 8–12 well-developed frontal setae reaching level of apex of pedicel; rows of frontal setae parallel except anteriormost 3–6 divergent; reclinate orbital seta present, 1 proclinate orbital seta present; ocellar setae as developed as upper frontals; outer vertical seta 1.5 × as long as postocular setae; gena and genal groove with silver pruinosity (Fig. 4C); gena with black setae; postgena silvery-gray pruinose with black setae; antenna black (Figs 4A, 4C); first flagellomere approximately 2 × as long as pedicel; arista micropubescent on basal half (Fig. 4C); palpus blackish (Figs 4A, 4C). THORAX. Dark brown with silvery pruinosity (Fig. 4A–B); chaetotaxy: acrostichals 0+0, dorsocentrals 3+3, intra-alars 1+2, supra-alars 1+3, postpronotals 3, notopleurals 4; postalar wall bare; postalar callus with 2 setae; scutellum with pair of basal and pair of subapical setae, pair of apical setae present or absent, and pair of discal setae present or absent; katepisternum with 3 setae almost in straight line; meral setae 5–7; proepisternum bare. WING. Hyaline, with dark brown veins (Fig. 4A–B); tegula dark brown; basicosta yellowish; vein R 4+5 with setulae dorsally at basal ⅔ of distance to crossvein r-m; vein R 1 bare or with 1–2 setae; cell r 4+5 open at wing margin; costal spine differentiated; third costal sector bare ventrally. LEGS. Blackish-brown, pulvilli yellowish-brown (Fig. 4A); mid femur with 3 median anterior setae, row of anteroventral setae, 2 preapical posterior setae, row of posteroventral setae, and without ctenidium; mid tibia with 2 median anterior setae, 2 median posterior setae and 2 posterior setae in apical third; hind trochanter without ventromedian pad of short, spiniform setae. ABDOMEN. Dark brown with silvery pruinosity (Fig. 4A–B); T4 with pair of median marginal setae and pair of lateral marginal setae; T5 with row of marginal setae; ST2–4 with marginal setae more developed than discal setae; ST5 with a membranous window, arms approximately 2.5 × of base length, and dense setae pattern (Fig. 3A). TERMINALIA. Syntergosternite 7+8 and apex of phallus black, other structures orange (Fig. 4D); cercus with numerous setae in basal half and sparse setae in apical half; cercal prongs divergent dorsally and pointed (Fig. 3B–C); surstylus almost triangular, with sparse apical setae (Fig. 3B); pregonite slightly curved, longer than postgonite, with apex bifurcated (Fig. 3D); postgonite with apex rounded and curved and short seta inserted on anterior margin near base (Fig. 3D); postgonal apodeme long and rectangular (Fig. 3D); basiphallus and distiphallus distinctly separated by dorsal membranous strip (Fig. 3D); vesica with superior and inferior projection, superior one bifurcated in ventral view and inferior one with pointed projection (Fig. 3D–E); juxta distinctly separated from paraphallus (Fig. 3D); acrophallus formed by median stylus, median process, and pair of lateral styli (Fig. 3D–E); median stylus almost straight in lateral view, median process tubular and lateral stylus with conspicuous spines in apex (Fig. 3D–E). Female Unknown. Remarks Microcerella desertum sp. nov. is morphologically similar to M. spinigena (Rondani, 1864). These species can be separated by the single proclinate orbital seta present in the male of M. desertum, which is absent in M. spinigena, as well as by the cercal prong being shorter than the base of the cercus, and juxta with an apical margin forming lobes in M. desertum (Fig. 3B–E), whereas in M. spinigena the cercal prong is longer than the base of the cercus, and juxta with straight apical margin (Mulieri et al. 2015: figs 187–188, 190). Distribution Chile (Atacama).