Parageron erythraeus ( Greathead, 1967 )

Gibbs, David, 2023, A world review of the bee fly tribe Usiini (Diptera, Bombyliidae) - Part 3: Parageron Paramonov s. lat., European Journal of Taxonomy 863 (1), pp. 1-162 : 35-38

Parageron erythraeus ( Greathead, 1967)

Fig. 34

Usia erythraea Greathead, 1967: 231 .

Etymology

‘Reddish’, from Greek ‘ypérythros’.

Type material

Holotype

ERITREA • ♂; “near Jebel Gheddem 9 April 1958 (leg. D.J. Greathead), 014587152”; NHMUK.

Paratypes ERITREA • 4 ♀♀; “near Jebel Gheddem 9 April 1958 (leg. D.J. Greathead) 014587153, 014587154 ,

014587156 & 014587157”; NHMUK • 3 ♀♀; “near Jebel Gheddem 9 April 1958 (leg. D.J. Greathead)”; NHMUK • 2 ♀♀; “near Jebel Gheddem 2 April 1958 (leg. D.J. Greathead)”; NHMUK • 1 ♀; “near Jebel Gheddem 2 April 1958 (leg. D.J. Greathead)” 014587155; NHMUK .

Redescription

MEASUREMENTS. Body length: 2.7–3.8 mm. Wing length: 2.4–4.6 mm.

Male

Only one male available, previously dissected. HEAD. Mouth margin relatively broad, almost as wide as width of proboscis at base, broadening out slightly into frons, entirely yellow in ground colour with thin coating of silky white dust, a slightly shinier border to the oral opening below. Frons approximately an equilateral triangle, lacking erect hairs. Eyes very narrowly separated by less than the diameter of an adjacent eye facet, thus linear, yellow strip broadening and becoming abruptly dark grey just in front of the front ocellus. Ocellar tubercle dark blackish, densely dusted silvery-grey, all ocelli in direct contact with the eyes; ocelli make an equilateral triangle. Very short, pale brown proclinate hairs on ocellar tubercle no longer than diameter of an ocellus. Eye facets in the central part of the upper two fifths enlarged, at least twice the size of those in lower part and around the margin. Occiput dark in ground colour except for narrow yellow strip next to eye in lower half; densely coated with grey dust and covered with white hairs longer than length of scape and pedicel combined. Antennae with scape yellow as frons, pedicel and postpedicel blackish, latter significantly longer than scape and pedicel together, the apical sulcus cut away such that the tip of the segment is much narrowed. Erect hairs on antennae almost absent or very short and inconspicuous. Palps very small and short, not swollen apically, pale yellow with short yellowish hairs. Proboscis moderately long, about equal to the mesonotum plus scutellum, black, tapering evenly, not swollen at base, naked, the basoventral membrane contrastingly yellow.

THORAX. Mesonotum blackish in ground-colour, yellowish only on post alar calli; densely coated with grey dust except for the two dust-free, roundish black spots on the thoracic suture laterally. Dark paramedian vittae also apparent from the very front of the mesonotum widening rearward to beyond wing bases, becoming difficult to see from some angles. Hairs of mesonotum white, absent on acrostichal line and paramedian vittae (except for a few acrostichals at rear), short on disc, longer on notopleuron where hairs are longer than scape and pedicel combined. Scutellum as mesonotum but ground colour vaguely yellow apically, white hairs short like dorsocentrals. Pleura concolourous with sides of mesonotum, grey dusted, pronotum and dorsum and posterior half of the anepisternum with white hairs like those on notopleuron.

WING. Membrane with a very faint yellow tinge, the veins pale yellowish. Crossvein r-m between basal third and middle of the discal cell, a little beyond m-cu. Anal lobe well developed with conspicuously convex margin, notably broader than anal cell.

HALTERE. Knob yellowish, stem slightly infuscated, especially at base.

LEGS. Coxae concolourous with pleura. Femora and tibia dark brown with tips of femora and very narrow bases of tibia yellow, trochanters and bases of femora also more yellowish. Front tibia paler brown than mid tibia, thinly silvery dusted. Legs covered with short white hairs, longest on the coxae and femora (hind legs missing but type description suggests they are as mid-legs).

ABDOMEN (MOSTLY REMOVED FOR DISSECTION SO REDESCRIPTION BARELY POSSIBLE). Tergites brownish, very thinly pale dusted. All tergites with dark basal colour shading into yellow posterior margins. All tergites with short pale hairs barely a quarter the length of each tergite (only basal tergites could be examined properly; sternites likewise but mostly creamy-yellow, narrowly dark basally, hairing as tergites).

GENITALIA. Largely dark brown, dusting and hairing similar to tergites.

Female

Seems to be very variable. Generally much more yellow in ground colour than male. Head mostly pale yellow with variable blackish areas on occiput and ocellar tubercle. Frons at narrowest wider than length of postpedicel, broadening towards front. Gena broader, shinier mouth margin slightly protuberant and raised at 45° relative to gena. Scape also sometimes pale below, postpedicel pointed, blunt-ended or with a double point, one forward, one dorsally situated. Eye facets all small. Hairing on occiput shorter. Dark spots on thoracic suture contrast more with the paler yellow ground colour, more or less dark striped medially and laterally, often leaving yellow dorsocentral areas, on other specimens these dark areas coalescing (in one case disc all dark). Scutellum yellow, pleura yellow, variably darkened. Thorax covered with yellowish dust and shorter pale hairs. Legs yellow, coxae variably darkened basally, hind tibia in apical half and tarsi blackish, fore and mid-basitarsus apically and remaining tarsal segments blackish (one specimen with legs more extensively infuscated). Abdomen usually more yellow than in male. 8 th sternite contrastingly dark brown apically.

Remarks

Only known from the type series, of which only one is a male. The 10 females are rather variable in colour and shape of postpedicel. The closely related Par. lutescens Bezzi and Par. orientalis Paramonov also display considerable variation in these characters. It is conceivable that the type series of Par. erythraeus consists of more than one species but I consider this to be unlikely. Until more specimens, including males, become available, there is insufficient reason to think that this variability is other than intraspecific.

Distribution

Eritrea.

Figures

Fig. 34. Parageron erythraeus (Greathead, 1967). a. Epiphallic complex ventral, b. Epiphallic complex lateral, c. Gonocoxite ventral. d. Gonocoxite lateral. e. Epandrium dorsal. f. Female genitalia ventral. g. Female sternite 8 ventral.