Cerodontha (Poemyza) ungula, Lonsdale, 2021

Lonsdale, Owen, 2021, Manual of North American Agromyzidae (Diptera, Schizophora), with revision of the fauna of the " Delmarva " states, ZooKeys 1051, pp. 1-481 : 1

Cerodontha (Poemyza) ungula sp. nov.

Figs 564-566

Description.

Wing length 2.1 mm (♂), 2.3-2.4 mm (♀). Length of ultimate section of vein M4 divided by penultimate section: 1.1-1.6. Eye height divided by gena height: 3.0-4.1. First flagellomere slightly longer than high, dorsal margin with very shallow angle between apex and middle. Arista short pubescent. Lunule angled posteriorly near base, visible portion (lateral base concealed by fronto-orbital plate) not much higher than wide, small, separated from ocellar triangle by its own height. Fronto-orbital plate and parafacial prominent, appearing thick when viewed laterally, continuing under eye as strong cheek; fronto-orbital plate, parafacial and anterior region of frons slightly bulging outwards so that anterior surface of head not appearing flat when viewed from above; fronto-orbital plate well-sclerotised, appearing continuous with ocellar triangle. Gena comparatively broad and rounded, not as projecting posteriorly.

Chaetotaxy: Two ori (sometimes three ori on one side); two ors; slightly decreasing in length anteriorly. Ocellar and postocellar setae subequal to fronto-orbitals. One row of strong orbital setulae. One pair of prominent setae apically on each palpus. Four dorsocentral setae, strongly decreasing in length anteriorly, with fourth seta barely larger than surrounding setulae. Four rows of acrostichal setulae. Acrostical seta absent; one female with duplicated dorsocentral in one acrostichal row.

Colouration: Setae dark brown with paler brown shine. Head dark brown; slightly darker or paler centrally on frons, which is covered with blackish pits; lunule and gena slightly paler; ocellar spot, back of head, clypeus, face, and venter of gena darker; ocellar triangle yellowish around dark ocellar spot; buccal cavity within arms of clypeus with dense orange to brown spicules. Remainder of body dark brown with notopleuron slightly paler and fore femur yellow for length less than apical width of femur; mid femur sometimes with slight yellowish tint apically. Wing veins light brown, becoming yellower towards base and often whitish posteriorly. Halter light yellow. Calypter margin and hairs light brown.

Genitalia: (Figs 564-566 ) Epandrium without supra-anal process. Surstylus small, rounded, directed inwards, with small setae. Ventral process of subepandrial sclerites with arm length equal to base width; smooth, with very small subapical point on outer surface. Basiphallus fused to ventroapical margin of phallophorus; sclerotised along left lateral and ventral surfaces, with nearly separate dorsal to right dorsolateral plate on distal 2/3. Hypophallus with one pair of flat, apically narrowing and desclerotised plates. Only left paraphallus evident as clear lobe. Mesophallus stem slightly wider at base, width ~ ¼ length; apical chamber small with simple rounded base, wider than long. Distiphallus tubule slightly longer than base + mesophallus, relatively straight with slight basal curve, lightly sclerotised, narrow with apex widened into darker, textured cup. Ejaculatory apodeme as long as basiphallus+ phallophorus.

Variation: Delaware female with first flagellomere darker and as long as high; paler brown or yellowish pigment absent from head, which is entirely dark brown; fourth dorsocentral more closely set to third dorsocentral.

Host.

Unknown, but the label of one paratype mentions “wheat”, which may represent a rearing record.

Distribution.

USA: DE, MI.

Etymology.

The specific name is Latin for "finger ring", referring to the pronounced ring around the eye.

Type material.

Holotype: USA. MI: Mio, 29.v.1937, H. Milliron (1♂, USNM).

Paratypes: USA. DE: Middleton, 17.v.1960, wheat (1♀, UDCC), MI: Mio, 29.v.1937, H. Milliron (2♀, USNM), E. Lansing, 29.v.1937, C. Sabrosky (1♀, USNM), Lapeer Co., 30-31.v.1937, C. Sabrosky (1♀, USNM).

Comments.

The new species Cerodontha (Poemyza) ungula is unique among the Nearctic Poemyza is its dark colouration, although the calypter is light brown; there are only four rows of acrostichal setulae, there is a slight point on the first flagellomere, and the fronto-orbital plate, parafacial and cheek are strong and projecting. The latter character is especially distinct but also seen in C. chillcottiella Spencer (Colorado), although in this western species the first flagellomere is more conspicuously pointed and the notopleuron and the centre of the frons are yellow. The genitalia are similar to those of C. pygminoides , although the surstylus of the new species is small and simple, the phallus is slightly stouter and shorter, the lateral and dorsal plates of the basiphallus slightly vary in shape and the left lateral margin is not produced, the apical chamber of the mesophallus is more rounded, the distiphallus is less broadly arched medially and with a more pronounced basal curve, and the apical cup on the tubule is larger and darker.

Figures

Figures 564 - 566. Cerodontha (Poemyza) ungula sp. nov., male genitalia 564 external genitalia, posterior 565 phallus, left lateral 566 phallus, ventral.