Amphoterus cribratus Bezzi, 1915

Midgley, John, Bellingan, Terence & Jordaens, Kurt, 2023, A revision of the hover fly genus Amphoterus Bezzi, 1915 (Diptera, Syrphidae) with the description of one new species, African Invertebrates 64 (2), pp. 149-163 : 149

publication ID	https://dx.doi.org/10.3897/afrinvertebr.64.100481
publication LSID	lsid:zoobank.org:pub:6EC41DFD-B88A-4265-BC1D-269F6933D60F
persistent identifier	https://treatment.plazi.org/id/A559588B-E468-5A45-9667-C75B02D9E4F1
treatment provided by	African Invertebrates by Pensoft
scientific name	Amphoterus cribratus Bezzi, 1915
status

Treatment

Amphoterus cribratus Bezzi, 1915 View in CoL

Figs 5 View Figures 3–6 , 9 View Figures 7–10 , 13 View Figures 11–14 , 18-20 View Figures 15–20

Amphoterus cribratus Bezzi, 1915: 117.

Amphoterus cribratus Bezzi - Brunetti 1926, 13: 166; Smith and Vockeroth 1980: 497; De Meyer et al. 1995: 7; Dirickx 1998: 5.

Eumerus cribratus (van Doesburg) - Whittington 2003, 10: 592. [citation only]

Material examined.

Holotype: Kenya • 1♂; British East Africa; T. J. Anderson leg.; NHMUK 010861152.

Description.

Male: length 9.5 mm, wing: 8.2 mm.

Head: Eyes broadly dichoptic. Face pale brown; yellowish white pilose; covered with dense yellow pollinosity. Gena pale brown; white pilose; with white pollinosity. Oral opening occupies about ⅓ of the distance between eyes. Frons reddish brown, with a short suture from the angle of the eye extending about ⅓ of the width of the frons, yellowish white pilose ventrally, darkening to pale brown dorsally; dense yellow pollinosity restricted to the area below the suture, though some sparse pollinosity may be present between the suture and the ocellar triangle. Ocellar triangle reddish brown; with sparse yellow to pale brown pilosity; lacking pollinosity. Ocellar triangle obtuse, posterior ocelli 1.25 times as far apart as the distance between anterior ocellus and posterior ocellus. Occiput reddish brown; pale brown pilose; sparsely yellowish white pollinose laterally, bare dorsally. Eye bare, facets of equal size across the eye. Scape short, reddish brown, with a few pale brown spines at the dorsoapical margin, lateroapical and ventroapical margins bare. Pedicel elongate, 1.25 times as long as postpedicel, 5 times as long as high, dark brown, covered in stout dark brown hairs, sparsely white pollinose. Postpedicel elongate, 2.8 times as long as high, dorsal and ventral margin almost parallel basally, widest at ¾ of length, dorsal margin sloping downwards in final ¼ and rounded ventroapically; dark brown; sparse white pollinose. Arista reddish brown.

Thorax: Scutum brown, punctate; postpronotum, the lateral part of the transverse suture and the postalar callus paler, brownish yellow; golden brown pilose, with longer, denser patches at the posterior margin between the postalar calli, and with longer pilosity on the postalar callus; with a horizontal vitta of sparse white pollinosity from the postpronotum to in line with the posterior corner of the eye and a horizontal vitta of sparse white pollinosity along the transverse suture and five vertical vittae of sparse white pollinosity, one medial and two mediolaterally reaching from the anterior margin of the scutum to ¾ of the distance to the suture and two laterally, between postpronotum and postalar calli. Scutellum with flattened apical rim, brown, yellow pilose, pilosity longer on rim. Posterior anepisternum, anterior anepimeron and dorsal katepisternum with golden pilosity. Katatergite with thin, fine golden pilosity. All lateral sclerites with white pollinosity, sparse on dorsal anepisternum. Metasternum with pale yellow pilosity.

Legs: Dark brown, except for the metafemur, which has some darker markings, and metatibia, which has a pale brown patch posteromedially; with pale yellow to white pilosity. Metafemur somewhat thickened medially, metatibia expanded apically, with a small groove venteromedially. Metabasitarsus large, as thick as metatibia and as long as other metatarsal segments combined.

Wing: grey infuscated in distal region, from subcostal anteriorly to branch of veins R2+3 and R4+5, to crossvein r-m to posterior margin of dm, hyaline basally. Cell r1 open for about ¼ of its length. Vein R2+3 straight for most of its length, turning sharply upwards as it joins the wing margin. Vein R4+5 straight. Crossvein r-m virtually straight. Vein M1 recessive, with two appendices projecting towards the wing margin. Cell dm with a single appendix at posterior corner. Spurious vein developed, though less than other veins. Wing microtrichose over most of the surface, bare only in posterobasal part of cell br, basal part of cell bm, anterobasal part of cell cup and anterior part of alula. Allula 2.3 times as long as broad. Calypter yellowish white, with darker margin, with long white pilosity. Haltere stem brown basally, becoming lighter distally, knob yellow.

Abdomen: Punctate, brown, with pale yellow pilosity anteriorly, yellow orange pilosity on apex of final segment. T2 slightly trapezoidal, about 2.5 times as wide as long, with longer pilosity at anterior corners, anterolateral and dorsomedial sections raised somewhat, with grooves between these sections, with white pollinosity from the anterior margin to the grooves, posteromedial section without pollinosity. T3 parallel sided, about 4 times as wide as long, with shallower grooves than T2, with a transverse vitta of white pollinosity on the anterior margin and diagonal vittae of white pollinosity from the medial part of the transverse vitta to the margin of the tergite. T4 parallel sided anteriorly, rounded posteriorly, about as long as wide, evenly rounded dorsally, without grooves; with a transverse vitta of white pollinosity on the anterior margin and diagonal vittae of white pollinosity from the medial part of the transverse vitta to the margin of the tergite.

Genitalia: Hypandrium narrow in lateral view, cerci rounded (Figs 18-20 View Figures 15–20 ).

Comments.

Bezzi (1915) describes the integument as black, but the holotype has brown integument with black punctation. This may be degradation, as other specimens from this collection appear to have lightened similarly (e.g., the A. braunsi specimen from Katberg, South Africa), or may be an interpretation error due to the quality of historic microscopes and light sources. Integument colouration should be interpreted with care in Amphoterus . The female described by Brunetti (1926) and specimens mentioned in De Meyer et al. (1995) could not be located and are considered lost. The figure caption in Bezzi (1915) refers to a female specimen, but the description is of a male, correctly referred to as such in the text. Likewise, Brunetti (1926) refers to the holotype in text as both female (line 16, page 166) and male (line 17, page 166). These are both likely typological errors.