Entesia pallidiventris (Malloch)

Winterton, Shaun L. & Irwin, Michael E., 2023, Revision of the South American stiletto fly genera Entesia Oldroyd and Melanothereva Malloch, with the description of a new genus (Therevidae: Agapophytinae), Zootaxa 5269 (1), pp. 1-82 : 38

Entesia pallidiventris (Malloch)

( Figs 23 ; 52 )

Dialineura pallidiventris Malloch, 1932: 253 — Stuardo-Ortiz (1946: 86 (as D. pallidinervis ) [catalogue]); Lyneborg (1968: 149).

Entesia pallidiventris ( Malloch, 1932) — Webb et al. (2013: 14 [catalogue, combination change]).

Diagnosis. Robust, brown and yellow species with grey pubescence and numerous setae; scape slightly bulbous; wing hyaline and smoky infuscate; male with two irregular rows of macrosetae on postocular ridge and upper occiput; male frons as wide as ocellar tubercle with extensive elongate setae; posterior surface of mid coxa with setae absent; medial furrow of prosternum with setae present; two pairs of supra-alar macrosetae; scutellum with two pairs of macrosetae.

Redescription. Body length. 9.0 mm (male). Head. Relatively broad; frons flat, pubescence dark yellowish tan with dark brown suffusion, extensive covering of elongate, black setae, male frons width at narrowest point slightly wider than ocellar tubercle; male postocular setae black, as two discrete rows irregularly arranged onto occiput, occiput convex, occiput pubescence grey; genal setae white; antenna scape slightly bulbous, cylindrical and equal length to flagellum, brown with grey pubescence, numerous erect large black setae; flagellum brown; relatively elongate. Thorax. Scutum grey with tessellate brown pattern, numerous elongate black setae, macrosetae black, chaetotaxy: np, 6; sa, 2; pa, 1; dc, 4; sc 2; scutellum concolourous with scutum; prosternum with setae in medial furrow; lateral lobe of cervical sclerite lacking macrosetae; pleuron with dense silver-grey pubescence, relatively few black setae admixed with white setae on anepisternum and katepisternum; katatergite setae white; coxae yellow, overlain with silver-grey pubescence, setae mostly white, macrosetae few in number, yellowish; mid- and hind coxa without setae on posterior surfaces; femora dark yellow, suffused brown apically, vestiture as short white setae, black on dorsal surface apically, admixed with elongate white setae ventrally; hind femur with one black subapical anteroventral and two yellowish subapical posteroventral macrosetae; tibiae and tarsi dark yellow; tibial and tarsal macrosetae elongate; wing hyaline, slightly smoky infuscate anteriorly, venation dark, yellowish basally, costal margin setae arranged in 3–4 rows; haltere stem pale with knob mostly brown. Abdomen. Sternite 1 lacking medial tuft of setae; abdomen base colour dark brown dorsally, yellow laterally and ventrally, male abdomen with silver velutum on tergites 2–7, male with elongate white setae on all segments except darker on posterior segments and terminalia; abdominal tergite 2 with short modified setae along posterior margin; terminalia dark yellow. Male terminalia. Epandrium sub-quadrangular, black medially; distiphallus broad apically, with apical spines (terminalia not dissected).

Comments. Malloch (1932) described E. pallidiventris in the therevine genus Dialineura with some doubt, as the setae and antennal morphology did not fit well with this genus. Subsequently, Webb et al. (2013) transferred it to Entesia . It appears correctly placed in Entesia at the moment based on characters such as presence of strong macrosetae on the forecoxa, modified setal patch posteriorly on abdominal tergite 2 and general shape of the male genitalia, including shape of the gonostyli with an erect, medially directed patch of elongate setae. This placement remains tentative though, as E. pallidiventris also displays superficial similarity to South American therevine genera in the Anabarhynchus genus group (e.g., Peralia Malloch, 1932 ), although the modified setal patch posteriorly on abdominal tergite 2 is a feature found only in many agapophytine genera and never in Therevinae . Still, several distinctive features of the male of this species indicate a rather isolated position in the genus Entesia , including the slightly thickened antennal scape, silver velutum pubescence on the abdomen, wide frons below the ocellar tubercle, scattered dark macrosetae on the occiput and two supra-alar macrosetae. This species is known only from the male holotype. The discovery of females and detailed examination of the female and male genitalia would likely confirm the subfamily and genus placement of this species.

Type material— Holotype male, CHILE: Ñuble Region : Perales, IX.1923 [-36.4205, -72.8696] (MEI159504; USNM) [examined].

Figures

FIGURE 23. Entesia pallidiventris (Malloch): A. Male, oblique view; B. same, lateral view.

FIGURE 52. Distribution map of Entesia pallidiventris, E. rubida and E. rubidaster.