Discovery of the digger wasp genus Odontosphex Arnold, 1951 (Hymenoptera, Apoidea, Spheciformes) in Central Asia, with description of a new species

The genus Odontosphex Arnold, 1951 is newly recorded from Central Asia. A new species, Odontosphex leleji sp. nov., is described and illustrated based on males from Turkmenistan (Badkhyz Nature Reserve, Eroyulanduz valley). Keys to males and females of all known species of Odontosphex are provided.


Introduction
Odontosphex Arnold, 1951 is a small and little-known genus including only six species. Arnold (1951) described this genus based on a single male of his new species O. bidens Arnold, 1951 from Mauritania. Currently, this species is also known from southern Palaearctic, i.e., Saudi Arabia, Iran and Pakistan (Bohart and Menke 1976;Pulawski 1991) (all collected Palaearctic individuals are females, attributed to this species tentatively).
Species of the genus Odontosphex inhabit sandy or salty biotopes in arid regions. Nesting biology unknown.

Materials and methods
This paper is based on the materials collected by N.V. Kurzenko (Vladivostok, Russia) during his expedition to Central Asia in 1990. Type specimens of the new species are deposited in collection of the Zoological Institute of the Russian Academy of Sciences (St. Petersburg, Russia) (ZISP) as well as in the personal collection of M.V. Mokrousov (MMC).
Photographs were taken with a combination of a digital camera Canon EOS M200 and Carl Zeiss Stemi 508 (Fig. 1A, B), Olympus SZX16 stereomicroscope (Figs 1C-E, 2A-C, 2F) and Olympus CX33 microscope (Fig. 2D, E). Final images representing a composite of several photographs taken at different focal planes were combined using Helicon Focus 7.6.1. All images were post-processed for contrast and brightness using Adobe Photoshop v. CC 2017 (×64).

Taxonomy
Taxonomic position of Odontosphex is controversial. Arnold (1951) assigned this genus to the subfamily Larrinae, but Menke (1967) pointed out certain contradictions and assigned Odontosphex to Philanthinae. Based on the unpublished doctoral thesis of Prentice (1998; personal communication by W. Pulawski), Pulawski (2021) placed Odontosphex within the subfamily Pemphredoninae.
Both Melo (1999) and Sann et al. (2018) attributed Odontosphex to Pseninae (Psenidae), based on morphology and DNA analysis respectively. At the same time, Odontosphex shares a number of substantial taxonomic features with Laphyragoginae, and this unique combination of characters does not occur in other taxa. The most important of these features are: hindwing with large and broad jugal lobe, as well as with media diverging before cu-a (Fig. 2F), similar forewing venation; single midtibial spur; contiguous midcoxae; occipital and hypostomal carinae form thin partition dividing hypostomal and occipital cavities; inner orbits of eyes converging above; antennal sockets not contiguous with frontoclypeal suture; upper margin of clypeus medially not expanded upward; pronotum with low collar; propodeum long; metapostnotum rather inconspicuously defined, triangular, its apex extending onto vertical posterior surface; male genitalia with volsella differentiated into digitus and cuspis; cerci absent.
All the data presented above therefore collectively suggest that further research is needed to reliably establish the taxonomic position of Odontosphex.
Diagnosis. The genus Odontosphex, according to Menke (1967), Bohart and Menke (1976) and Pulawski (1991) with clarifications, is characterized by: eyes in males nearly holoptic, in females conspicuously converging above; lateral ocelli vestigial and close to midocellus; clypeus transverse and apicomedially with two to seven teeth, no lateral clypeal brushes in male, upper margin medially not unusually expanded upward; antennae short and with F1 not longer than F2, antennal sockets separated from clypeus by not more than two their diameters; no subantennal sclerite defined by lines from antennal sockets through tentorial pits to clypeus; a small tubercle between antennae; mandible edentate and with socket not completely closed, no hairbrushes in male; palpal formula 6-4; pronotal collar thin, depressed and appressed to scutum; episternal sulcus absent; scrobal sulcus absent or weakly indicated; omaulus present or absent; propodeum long; metapostnotum defined, wide and triangular, with a median longitudinal carina, its apex extending onto vertical posterior propodeal surface; foretarsal rake of female consists of short spines, absent in male; midcoxae nearly contiguous; midtibia with one apical spur; hindcoxa with lamella at inner apex; hindfemur truncate apically; plantulae present; marginal cell of forewing acutely narrowed and slightly separated from wing edge toward apex; second submarginal cell not petiolate in front and receiving both recurrent veins; hindwing media diverging before cu-a; jugal lobe occupying about four-fifth length of anal area; metasoma sessile; female S6 not cleft apically; male S8 somewhat narrowed and triangularly emargined at apex; female with pygidial plate; no cerci; volsella differentiated into digitus and cuspis. Pulawski, the new species differs by short setation on vertex and T1, and by coloration of the body with brown, yellow and reddish pattern (O. damara has long erect setae on the vertex and base of T1, and predominantly black body).
Description. Male. Body length 5.8-7.1 mm (holotype: 6.0 mm); fore wing length 3.7 mm (holotype). Head ( Fig. 2A-C). Head ratio H:W = 0.84 ( Fig. 2A); eyes markedly convergent above, vertex linear, least interocular distance equal to 0.3 × transverse midocellar diameter, with central longitudinal sulcus (Fig. 2B, C) which continues behind as very thin line. Posterior ocelli elongated, flattened and inconspicuous. Clypeus short, about half length from anterior margin to antennal sockets at middle; central part of anterior margin with two long median and two triangular lateral teeth (Fig.  1D). Occipital carina well developed, joining hypostomal carina and then forming thin partition dividing hypostomal and occipital cavities. Antennae thickened, flagellomeres without swellings or excisions, F1-F5 nearly as long as wide, F6-F11 longer than wide; F4-F9 with tyloids, which are very small, in form of tubercles on F4 and F9, and oval, protruding and clearly visible on F5-F8 (Fig. 1C). Lower frons and clypeus with dense silver setation concealing integument; upper frons dull, with spaced small punctures, ocellar area shiny with larger punctures about 0.5-1 diameter apart; gena slightly shiny, with obscure fine punctures. Mesosoma (Fig. 1E). Omaulus short and visible only in upper part ventrally of pronotal lobe; scrobe unclear. Mesoscutum with wide depressed admedian area limited by furrows; notauli short but distinct and depressed; parapsidal furrow thin, not reaching anterior and posterior edges of mesoscutum (Fig. 1E). Upper third of metapleuron longitudinally elevated. Mesonotum with fine and dense punctation in anterior part, with scattered punctures at middle and more dense punctures laterally and posteriorly. Mesoscutellum with scattered punctures at middle and more dense punctures posteriorly. Metanotum matt, microsculptured, densely punctate. Dorsal part of metapostnotum punctato-rugose, almost smooth and shiny apically. Mesopleuron densely punctate, punctures partly contiguous, interspaces shiny. Propodeum dorsolaterally matt and finely wrinkled, densely punctate ventrally. Mesoscutum anterolaterally, metapostnotum at center and mesopleuron with dense semierect and sparse erect setae, length of some setae more than one midocellar diameter. Propodeum posterolaterally with erect setae, length about 1.5 midocellar diameter. Wings (Fig. 2F). Venation typical for genus. Setation. Foretarsal rake lacking, represented only by thin and rather sparse bristles; forefemur with dense semierect and sparse long erect setae ventrally. Metasoma with dense short setation forming indistinct bands at apical parts of segments. Genitalia (Fig. 2D, E). Penial valve hooklike; cuspis and digitus longitudinally elongate. Coloration (Fig. 1A). Black with reddish (brownish) and yellow pattern. Head black with light brown or yellowish mandibles (except base and apex), labrum and distal parts of mouth appendages; antenna brownish ventrally and darkened dorsally, apical flagellomeres almost completely light brown. Mesosoma black, pronotal lobe yellow. Fore and mid femora dark brown with lighter apex; hind femur, tibiae and tarsi yellowish or light brown. Tegula and wing veins basally yellow, veins brownish apically; forewing Sc+R mostly brownish. Metasomal segments 1-3 predominantly reddish brown, apical parts of segments translucent, metasomal apex reddish brown; in particular specimen, first three segments completely red.