Sphex caelebs, Doerfel, Thorleif H. & Ohl, Michael, 2015

Doerfel, Thorleif H. & Ohl, Michael, 2015, A revision of the Australian digger wasps in the genus Sphex (Hymenoptera, Sphecidae), ZooKeys 521, pp. 1-104 : 48

Taxon classification Animalia Hymenoptera Sphecidae

Sphex caelebs sp. n.

Material examined.

Holotype. ♂, AUSTRALIA:WA: Westonia, 31°11'53"S, 118°45'31"E, 15.03.2007, L. C. & M. G. Brooker (AMS).

The collecting locality is shown in Fig. 42D.

Diagnosis.

The presence of a few dark erect setae on the clypeus combined with partially orange legs (mainly parts of the anterior surface of the foreleg, as seen in Fig. 30B, and the inner hindtibial spur including pecten) make Sphex caelebs unique among the male Australian Sphex (the female of this species is unknown). The habitus and mesosomal sculpture resemble some Sphex modestus , which possesses an only inconspicuously raised metanotum and dense white or yellowish tufts of setae on the metasomal sterna that are absent in Sphex caelebs .

Description.

Female: Unknown.

Male: Body length 18.1 mm. Body black, but the following are orange-brownish: basal half of mandible, anterior surface of foreleg from distal half of femur up to tarsomere IV, distal half of anterior surface of midfemora, inner hindtibial spur including pecten, basal half of claw. Wing membrane hyaline, forewing with slightly fuscous band at apex. Wing veins dark brown. Free clypeal margin simple, concave medially. Appressed pubescence on clypeus and frons silvery-white, a few dark erect setae on clypeus, remaining erect setae on clypeus as well as those on frons uniformly silvery-white. Clypeus medioventrally with narrow glabrous stripe. Distance between hind- ocelli nearly equal to their shortest distance to compound eyes. Pubescence on mesosoma silvery-white, on scutum slightly denser laterally. Scutellum convex, with shallow medial impression. Pubescence on propodeal enclosure sparse, leaving sculpture fully visible. Length of petiole 1.6 × length of flagellomere II. Tomentum moderately dense on metasomal tergum I and II. Metasomal terga V and VI sparsely covered with erect silvery setae. Metasomal sterna II–VI mostly glabrous, apical half of sternum VII and all sternum VIII covered with silvery pubescence. Metasomal sternum VIII entire, its lateral margin straight.

Discussion.

It must also be assessed if Sphex caelebs is the undescribed male of an already known species. In the Sphex subtruncatus group, there are seven species of which males are yet unknown or where matching of males and females was first proposed in this study. In none of these, however, is the leg coloration comparable to Sphex caelebs , and additional characters indicate its status as a separate species. For example, only two of the seven species also have dark erect setae on the clypeus. These two, however, are much larger than Sphex caelebs ; one of them, Sphex ahasverus , has darkened wings and golden pubescence on the propodeum and the other one, Sphex corporosus , has an unusually short petiole, the characters that are lacking in Sphex caelebs .

Etymology.

Caelebs is a Latin noun meaning "unmarried man", referring to the fact that the species is currently known only from a single male.