Sphex pretiosus, 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 : 63-64

Taxon classification Animalia Hymenoptera Sphecidae

Sphex pretiosus sp. n.

Material examined.

Holotype. ♂, AUSTRALIA:NSW: 56 miles W of Cobar, Baznatos Tank, 01.01.1966, O. W. Richards (BMNH). Paratypes. AUSTRALIA:NSW: Binnaway, 1♀, Dec 73, A. Smith (AMS); Gilgandra, 1♀, 06.11.1987, G. A. Holloway (AMS); between Whitecliff and Wilcannia, 2♂, 09.03.2001, M. Ohl (ZMB); SA: 27 km WSW Whyalla, 33°06.5'S, 137°19.0'E, 1♀, 28.12.2010, V. Ahrens & W. J. Pulawski (CAS).

Diagnosis.

This species is unique among the Australian Sphex in having a more or less sharp transition in the color of the pubescence on the clypeus and the propodeal dorsum. On the ventral part of the clypeus and the outer and posterior margin of the propodeal enclosure, the pubescence is silvery-white; while it is golden on the dorsal part of the clypeus and silvery-golden to golden on the propodeal enclosure. Moreover, the metasomal sternum VIII in males is spoon-shaped and has a gentle notch at the apical margin (Fig. 39B).

Description.

Forewing membrane posterobasally with slight yellow tinge, with fuscous band at apex. Wing veins bright orange, brown near apex. Appressed pubescence on ventral part of clypeus silvery-white, on dorsal part and frons silvery-golden. Erect setae matching respective color of appressed pubescence on clypeus, silvery-white on frons. Clypeus almost entirely covered with pubescence. Distance between hind- ocelli 1.25 × their shortest distance to compound eyes. Pubescence on scutum denser laterally and posteriorly. Scutellum convex, with medial impression. Pubescence on propodeal enclosure not completely concealing sculpture. Propodeal pubescence outside enclosure and on petiole silvery-white. Length of petiole nearly twice length of flagellomere II. Tomentum moderately dense on metasomal tergum I.

Female: Body length 17.7-18.8 mm. Body black except mandible reddish basally. Free clypeal margin with two lobes medially and with another less-pronounced lobe on each side of the aforementioned; distance between each two lobes less than 1/8 length of flagellomere II. Forebasitarsal rake with 12 long spines. Pubescence on collar, scutum and propodeal enclosure silvery-white to silvery-golden. Tomentum moderately dense on metasomal tergum II.

Male: Body length 18.4-18.7 mm. Body black. Free clypeal margin slightly concave, convex near center. Pubescence on collar and scutum silvery-golden to golden, on propodeal enclosure golden. Tomentum very dense on metasomal tergum II. Metasomal terga V and VI with few bristles. Metasomal sterna III–VIII with silvery pubescence. Metasomal sternum VIII mostly covered by VII; with long, narrow, spoon-shaped extension that has a small notch at apical margin.

Variation.

In a few of the examined specimens, the metanotum is moderately raised, and in one of these, there is a slight median impression on it. A raised metanotum with an impression is usually distinctive for species of the Sphex argentatus group, but since the raising of the metanotum and the depth of the impression in the most extreme known cases of this species are only comparable to the least extreme cases of examined specimens of the Sphex argentatus group, Sphex pretiosus is tentatively placed in the Sphex subtruncatus group.

Discussion.

Males and females of Sphex pretiosus have nearly identical features that are also unique among the Australian species, such as the transition between golden and silvery-white pubescence on the clypeus and the propodeal dorsum. Also, the conspicuously modified sternum VIII of the male substantiates a full species status. Fig. 39C shows that the proposed males and females at least occur in the same region.

Etymology.

Pretiosus is a Latin adjective, meaning “valuable” or “costly”. It metaphorically refers to the combination of golden and silvery pubescence on the mesosoma of this species.