Pteromicra zariae Knutson & Deeming, 2018

Knutson, Lloyd V., Deeming, John C. & Ebejer, Martin J., 2018, The Snail-killing Flies (Diptera: Sciomyzidae) of West Africa, Zootaxa 4483 (1), pp. 67-100 : 75

Pteromicra zariae Knutson & Deeming sp. n. ³♀

(Figs 5, plate 8b )

Body length ♂ and ♀ 3.0mm, wing length 2.0mm. All setae and setulae black except for small scutal setulae and aristal and squamal setulae, which are white. Head slightly higher than long. Frons very slightly narrowed anteriorly, uniformly shining blackish brown, greatest width at occiput 1.25 x its length at midline; 1 strong posterior fronto-orbital slightly smaller than ocellar setae; short, black scattered setulae present all over frons. Sparse silvery white pruinosity on ocellar triangle, on orbital plates, anteriorly along eye margin and extending onto occiput as a pair of similar stripes meeting at cervix. Gena one quarter x height of eye, with 2 or 3 indefinite rows of short black setae along lower margin, yellowish brown, heavily silvery white pruinose. Middle of face shiny, fading into yellowish-brown parafacies, denser white pruinosity of gena extending onto face along eye margin. Black setae of gena extending to lower margin of face, deep velvety blackish orbito-antennal spot triangular. Postocellar setae weak and 2/ 3 x length of, to almost as long as, inner vertical seta. Antennal scape minute, yellow, pedicel twice as long as scape along dorsal margin, yellow; postpedicel elongate elliptical, yellow with brown tawny to brownish apical margin on both inner and outer faces; arista with basal segments brown, with short, white moderately dense plumosity. Occiput shiny black. Palpus yellowish brown. Thorax black, shiny, somewhat more so anterodorsally, more or less uniformly covered in sparse white pruinosity, but shiny black on lower half of katepisternum, scutum with pair of distinct, broad vittae extending from anterior declivity to posterior 1/5 of scutum, then a medial black velvety triangular spot between dorsocentral rows extending from scutellar margin. Meron more densely pruinose. Katatergite densely black pruinose. 2 pairs ntpl, 1 ppn, 1 sa, 1 pa, 1 prsc dc, 1 pair small acrs setae slightly anterior to dorsocentrals, rest of scutum with short scattered setulae, 2 pairs marginal sc, anterior pair 2/ 3 x length of well-developed posterior pair, scutellum rather dull black, dorsally with short fine dark setulae; 1 strong slightly backwardly directed anep at upper anterior corner of anepimeron, 2 short setae 1/3 length of anep above and in front of it. Rest of anepisternum and anepimeron bare. Katepisternum with short black setae on upper half. Haltere, including most of stem, whitish yellow, extreme base brownish. Wing greyish hyaline with uniform distribution of microtrichia, with diffuse greyish markings as in Fig. 35, or fainter, veins brown; anterior crossvein at mid length of discal cell; first longitudinal vein ending slightly beyond anterior crossvein; second vein rather strongly arched towards costa; ultimate section of fifth longitudinal vein evanescent just before wing margin; anal vein evanescent on apical 1/5, a slight fold proceeding to wing margin may give the impression that the vein continues to margin; posterior crossvein straight. Squama as wing membrane with yellowish fringe. Legs yellow except for tibia and 4 basal tarsomeres of fore leg, which are black, fifth tarsomere white. Mid coxa shiny black above on external surface and apices of front and hind femora blackish above. Anterior margin of fore coxa with 2 strong setae below middle. Anterior femur with 2 or 3 of strong dorsal and external setae, lacking a pecten. Mid femur with 2 or 3 strong anterodorsal setae along apical 1/5. Mid coxa with strong setae externally near apex. Abdomen shiny blackish brown with posterior margins of tergites darkest, tergites and sternites with sparse whitish pruinosity. Male postabdomen (Fig. 5): female cerci yellow with unspecialized chaetotaxy.

Diagnosis. This and the undescribed species from Tanzania (Pawe Mt., 1♂, 30.v.1963, G. Hernrich (CNC) are the only species of the genus so far known from Africa south of the Sahara. The Tanzanian species also has a patterned wing, but is immediately recognizable on account of its much greater size (body length 6mm), the last 2 segments of the fore tarsus being white, the antenna inclusive of arista being completely black, and the hind tibia with a basal and apical black ring. Pteromicra rudis Knutson and Zuska from Montana is the only other described species of this genus having a patterned wing. However, in that species the wing is faintly but more uniformly dark over most of its surface, lacking spots; it lacks the conspicuous white arista of P. zariae and it has the fore tarsus dark with only the apical half of the apical segment yellowish. As with the Palaearctic species, P. glabricula (Fallén) and the Holarctic P. pectorosa (Hendel) the new species has only a single fronto-orbital seta. However, in those two species the wing is not patterned, the front femur is black on at least the apical 1/3, and both have a pecten.

Holotype ♂, NIGERIA: Zaria , Dumbi Wood, 14.vi.1970, J.C. Deeming ( USNM) . Paratypes, same data as holotype, but small pond, 1♀, 26.x.1969 ( IARS) ; 1♀, same locality, 25.x.1979 ( NMWC) (all collected by Deeming) .

Biology. Unknown.

Figures

PLATE 8. Figs 35–38, wings of Sciomyzidae: 35—Pherbellia (Graphomyzina) kivuana Verbeke, 36—Pteromicra zariae sp. n., 37—Sepedon (Mesosepedon) knutsoni Vala, Gbedjissi & Dossou, 38—Sepedonella nana (Verbeke); 39—Sepedon (Mesosepedon) knutsoni, habitus, 40—Sepedon (Sepedomyia) nasuta (Verbeke) head, lateral.