Pachylophus nigeriensis, Deeming, 2018

Deeming, John C., 2018, A revision of the Afrotropical species of Pachylophus Loew (Diptera: Chloropidae) and some related Ovoviviparous genera, Zootaxa 4482 (1), pp. 1-51 : 16-17

Pachylophus nigeriensis sp. n.

( Plate 4 , Figs 17, 18; plate 5, Fig. 24; plate 9, Figs 42, 43)

Diagnosis. A small species with frons hardly projecting in front of eye, frontal triangle black, undusted, deeply concave medially, with its straight lateral margins only a little longer than its width at base, the parafacial and gena grey dusted throughout, the palpus yellow, the thorax black on all but the katepisternum, the anepimeron completely dusted and katepisternum dusted on all but the part above level of mid coxa, scutellum obtusely pointed apically, haltere with stem black and knob white and the legs ferruginous with tarsi somewhat darkened towards apex.

Description. Male. Head higher than long, intensively infuscate on entire upper half of occiput, less intensively so on lower; ocellar triangle extending three fifths of the way from anterior ocellus to fore margin of frons; postpedicel rather short, rounded, its dorsoapical angle about 85°. Thorax with pale grey dusting; scutum undusted between the postptonotal lobes from neck to suture, on a short broadly rounded median projection extending back to the point of the beginning of the prescutellar declivity and on a narrow line just outside the dorsocentral line extending back to the level of wing base; the widely-separated scutellar marginal setae weak, slightly inclinate and as long as the distance separating their bases; notopleural seta reduced to a minute hair; prescutellar dorsocentral seta and postalar seta both absent. Hind tibia with sensory area distinct, pilose, occupying slightly less than one third of its length. Wing greyish hyaline with brown veins; ultimate section of vein R4+5 slightly curved backwards on its apical half. Tergites dark brown, weakly subshining through dark grey dust.

Length about 3.4mm, of wing 3.4mm.

Female resembling male in all but postabdominal characters.

Puparium 4.15mm in length, 1.1mm in greatest breadth, smooth-surfaced, pale yellowish brown with posterior spiracular plates dark brown; mandibular sclerite ( Plate 5 , Fig. 24); anterior spiracles ( Plate 4 , Fig. 18) ventrallysituated with their long axes longitudinal, quite close together, each situated on a dome of colourless and extremely thin cuticle and bearing about 25 brown digitations apiece; posterior spiracles ( Plate 4 , Fig. 17) each bearing about 11 ovate apparent respiratory openings on a heavily sclerotised horseshoe-shaped base that is raised above the level of the surrounding puparial cuticle.

Of the material cited below from Bauchi 4 out of 5 dissected females were found each to contain a single larva that was as long as its abdomen, and one of the females was reared from a pupa found in a grass fragment. Since it transpired that there was a small admixture of Leersia hexandra to the Oryza barthii , the hostplant cannot be cited with certainty.

Material : Holotype ♂, N. NIGERIA: Bauchi, pond with Oryza barthii , 1–12.iv.1990, J.C. Deeming ( NMWC) . Paratypes 15♂ 29♀, same data as holotype ; 28♂ 26♀, (1♂ 12♀ with Laboulbeniales ) same data but 1–7.iii.1997 ; 1♂, Zaria, Samaru, 16.iv.1966, J.C. Deeming; 1♂ 1♀, same data but 26.i.1970 ; 1♂ 2♀, same locality, 26- 28.iii.1973, L.V. Knutson (in NMWC, USNM & NHMUK) ; 4♀, (1 with Laboulbeniales on abdomen) GAMBIA: W. Div., Kombo Distr., Lamin Bridge , rice field near Lamin Bolan , tidal waterway, on young rice, 2.ix.1997, D.J. Mann ( NMWC, OUM & MAFY) ; 2♀, marsh near Bakau , 9.iv.1977, (X89) ; 2♂ 2♀, Abuko , 3.iv.1977, (X85) ; 96♂ 75♀, (4♀ with Laboulbeniales on abdomen) ETHIOPIA: Gojam Province , swamp 1km N. of most southerly point of Tana Lake, swamp, 27.iii.1995, (X1031) ; 2♂ 1♀, Gonder Prov., Blue Nile at T'is Isat Fwafwate waterfall, 8.iii.1995, (X1032), all M. v. Tschirnhaus ( ZSM).

A further 8 specimens, not included in the type series but of same data as the holotype, were found to be bearing Laboulbeniales projecting from the tergites. Dr. W. Rossi, informed me that it belongs to a group of species described by Thaxter in 1918 and never found since. These fungi produce morphologically different forms according to the part of the insect in which they develop. Further material collected at the same locality included specimens having Laboulbeniales on the legs also. This, Dr. Rossi identified as Laboulbenia pachylophi Thaxter , which was originally described from the legs of Pachylophus frontalis Loew.

A further 1♂ 3♀, MADAGASCAR: S. bank of River Mangoky, Bevoay, 21°50'S 43°53'E, 19.ii.1984, M.v. Tschirnhaus (X1182) ( ZSM) and 4♂ 2♀, 13km. WSW of Ihosy at River Ihazovotsy, 22°25'S 46°00'E, 11.ii.1984, M.v. Tschirnhaus ( ZSM except for 2♂ in NMWC) differ in having the frons infuscate except for a narrow anterior border. Since their identity is in doubt they are not included in the type series.

Figures

PLATE 4. Figs 15, 16, Pachylophus mirabilis sp. n.; 15, antenna in profile; 16, pedicel from above. Figs 17, 18, Pachylophus nigeriensis sp. n.; 17, puparium, posterior spiracles; 18, puparium, anterior spiracles; 19, Pachylophus femoratus (Johnson), puparium, posterior spiracles; 20, Pachylophus flavipes Lamb, puparium, posterior spiracles.

PLATE 5. Figs 21–25, Pachylophus spp. larval mandibular sclerites; 21, P. pellucidus Becker; 22, P. femoratus (Johnson); 23, P. flavipes Lamb; 24, P. nigeriensis sp. n.; 25, P. varipes Adams. Pachylophus pellucidus Becker, 1910 (Plate 1, Figs 1–3; plate 5, Fig. 21; plate 10, Figs 47–49)