Phthiria laeta Bezzi, 1921

Genus Phthiria Meigen, 1803.
The Phthiriinae are readily separated from the similar looking Usiinae by the first antennal flagellomere, which in Phthiriinae has a subapical sulcus bearing a style and dorsal and/or ventral processes; also wing vein M2 is present (four posterior cells). Only the nominate genus, Phthiria, is present in Southern Africa.
Sexual dimorphism of adults is present and distinct: Males have holoptic eyes and are usually dark or black with infrequent pale coloration; females usually are paler with bands on the abdomen and/or vittae on the thorax or other distinct patterns.


Phthiria laeta Bezzi, 1921
While most Phthiria species occur in the Western and Northern Cape, this is the only Phthiria known from the NE parts of South Africa. Female easily identified by the black and yellowor pale banded abdomen and the reddish legs. Body on the whole less humped and broader than in other species.

Original description in:
Bezzi, M. 1921. On the bombyliid fauna of South Africa (Diptera) as represented in the South African Museum. Annals of the South African Museum 18
https://www.biodiversitylibrary.org/page/1540304#page/112/mode/1up

Female:
Head reddish, quite opaque; occiput broadly black in the middle; frons with a longitudinal, black, median stripe.
Antennae quite black, with the third long joint, about linear, ciliated above, with very short terminal style at its upper angle.
Thorax blackish and opaque on the back, with a fine dark grey tomentum and with whitish hairs; the humeri, a narrow stripe above the notopleural line, a broader stripe above the root of the wings and the postalar calluses yellow; the hairs are long and whitish. Scutellum yellow, with a very narrow basal black stripe.
Abdomen rather swollen and convex, quite opaque, clothed with whitish hairs; each segment is of a deep black colour, with a proportionally broad, equal and complete yellow stripe at the hind border; the second segment has the black part twice as broad as that of the following segments.
Legs reddish, with pale yellow coxae, infuscated tibiae, and blackish tarsi; anterior femora with a black longitudinal stripe on the outer side.
Wings greyish hyaline, with yellowish stigmae; veins black, with yellowish base; discal cross-vein placed at about the middle of the discoidal cell; cubital fork about three times as long as broad at end; anal cell briefly stalked.

Description of male in:
Hesse, A.J. 1975. Additions to the South African species of Phthirinnae and Usiinae (Diptera: Bombyliidae) with keys to all the known species. Annals of the South African Museum 66
https://www.biodiversitylibrary.org/page/40911307#page/351/mode/1up

Male: Body mainly black, only narrowish hind margins of sternites pallid; broadish hind margins of tergites on sides appearing greyish white, due to greyish white tomentum.

Distribution: Gauteng & KZN Drakensberg (Van Reenen)

iNat observation: https://www.inaturalist.org/observations/153442998

Posted on February 08, 2024 12:50 PM by traianbertau traianbertau

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