Two new morphologically interesting species of the genus Ephedrus Haliday (Hymenoptera, Braconidae, Aphidiinae)

Here we describe two new Ephedrus species from the Biologiezentrum Linz ́s collection: Ephedrus antennalis sp. nov., which possesses 12-segmented antennae, a unique character within the genus Ephedrus; and E. carinatus sp. nov., which represents an additional member of the root aphid parasitoid group within


Introduction
There are about 40 known species of the genus Ephedrus Haliday, 1833 around the world (Akhtar et al. 2011;Kocić et al. 2019). This genus is characterized by the presence of many plesiomorphic characters (e.g., antennae with 11 segments in both sexes, which is a unique case within the subfamily, a fore wing venation pattern close to the braconid ancestor and long oviposition time), all of which suggest that it is probably one of the basal genera within the subfamily Aphidiinae (Gärdenfors 1986;Belshaw and Quicke 1997;Sanchis et al. 2001). Additionally, black parasitized aphids ("mummies") are specific for Ephedrus and very few other genera (e.g., Paralipsis Förster, 1863, some species of Pauesia Quilis, 1931). A single species of the genus Ephedrus, known as an obligatory parasitoid of root aphids (Ephedrus validus (Haliday, 1833)), possesses accompanying adaptations to a subterranean mode of life. This species exhibits features such as small eyes and short and strong legs, along with a densely setose body as a protective trait against the honeydew of waxy root aphids. Interestingly, male specimens are less pubescent, and that character led Gärdenfors (1986) to suspect that males are not in contact with root aphids and that they probably do not follow females beneath the surface of the ground. It is known that Ephedrus plagiator (Nees, 1811), which is a broadly polyphagous species, also occasionally parasitizes the root aphids (Starý 1961;Gärdenfors 1986). Furthermore, while European, African and Central Asian populations of Ephedrus persicae Froggatt, 1904 are biparental (Takada 1979;Gärdenfors 1986), some Far Eastern, Australian and USA populations possess an asexual mode of reproduction (Starý and Schlinger 1967;Takada 1968;Gärdenfors 1986). Based on relevant literature, it is evident that numerous species from the genus Ephedrus possess a range of biologically and ecologically complex features.
After examination of the Biologiezentrum Linz´s collection, we discovered two Ephedrus species new to science with some unusual morphological traits. Here we describe Ephedrus antennalis sp. nov. and E. carinatus sp. nov. and discuss their relationships within the genus Ephedrus.

Material and methods
Specimens were collected by sweeping from the Western Caucasus (Russia) and from Austria (before World War II -a historical record). Both specimens are slide-mounted with Berlese medium. Study of the external structure and the measurements was undertaken with a LEICA DM LS phase-contrast microscope (Leica Microsystems GmbH, Wetzlar, Germany). The terminology used in this paper regarding diagnostic characters is based on that of Sharkey and Wharton (1997).
Female. Head. Malar index equal to approximately 0.20 of the longitudinal eye diameter. Clypeus oval with eight long setae. Tentorial index approximately 0.35. Maxillary palps with four, labial palps with two palpomeres. Antennae 12-segmented, filiform, with semierect setae which are shorter than half of the segments' diameter ( Fig. 1A). F1 and F2 elongated, 4.25 and 3.6 times as long as wide, respectively ( Fig. 1B). F1 subequal to F2. F1 with two, F2 with three ( Fig. 1B), F3 and F4 with five longitudinal placodes. Antennae not thickened towards apex, F9 well separated from F10 (whereas in E. persicae F8 and F9 are not well separated and form a kind of club).
Colouration. Head light-brown. Mouthparts light-brown. Scape brown, pedicel and F1 yellow to light-brown, remaining parts of antennae brown. Legs brown with light-brown tarsi. Petiole brown, remaining parts of metasoma light-brown to brown. Ovipositor sheath brown. Diagnosis. On the basis of fore wing venation (3SR vein longer than 2SR vein) (Fig. 2F), this species belongs to the plagiator species group. The new species morphologically resembles E. validus in possessing a reticulated petiole (Fig. 2G) and propodeum (Fig. 2E) and a densely setose ovipositor sheath (Fig. 2H), features that point to a subterranean habitat where it probably parasitizes root aphids. However, it differs clearly from E. validus in having wide and rugose notaulices along the dorsal side of the mesoscutum (Fig. 2D) (vs. shorter notaulices reaching the first third of the mesoscutum in E. validus (Fig. 3A)), second flagellomere approximately 3.2 times as long as wide (Fig. 2C) (vs. 2.7-2.8 times as long as wide in E. validus (Fig. 3B)) and a petiole approximately 1.35 times as long as wide at the spiracle level (Fig. 2G) (vs. a more elongated petiole, 1.4-1.6 times as long as wide at the spiracle level in E. validus (Fig. 3C)).  Female. Head. Malar space equal to approximately 0.32 of longitudinal eye diameter. Clypeus oval, densely setose with over 20 long setae. Tentorial index approximately 0.48. Maxillary palps with four palpomeres, labial palps with two. Head approximately 1.3 times wider than mesoscutum ( Fig. 2A). Antennae 11-segmented, filiform, slightly tickened towards apex, with semierect setae which are shorter than half of diameter of the segments (Fig. 2B). F1 elongated, with a constriction in the first half, approximately 5.8 times as long as wide and approximately 1.8 times longer than F2 (Fig. 2C). F2 approximately 3.2 times as long as wide. F1 and F2 with two or three longitudinal placodes (Fig. 2C), F3 and F4 with four longitudinal placodes. F8 and F9 well separated.
Colouration. Head black. Scape and pedicel yellow to light-brown. F1 yellow, remaining part of antennae brown. Mouthparts light-brown. Petiole light-brown to brown. Legs light-brown with dark apices. Metasoma brown. Remaining body parts brown to black.
Distribution and biology. Ephedrus carinatus sp. nov. is known only from a historical record from Austria. We assume that it is a parasitoid of root aphid species.
Etymology. The new species takes its name from the developed notaulices on the mesoscutum. Starý (1959) established the subgenus Lysephedrus Stary, 1959, with the nominative species Ephedrus (Lysephedrus) validus. Later on, in a taxonomic and biological revision of Palaearctic species Gärdenfors (1986) divided the genus Ephedrus into three subgenera -Ephedrus Haliday, 1833, Breviephedrus Gärdenfors, 1986and Lysephedrus Starý, 1958. Davidian (20072018) considers the subgenus Lysephedrus as a separate genus. However, on the basis of molecular markers and morphology, in an integrative study, Kocić et al. (2019) established Ephedrus (Lysephedrus) validus to be nested within species of the subgenus Ephedrus and assigned it a status of junior synonym of the subgenus Ephedrus. Here we describe a new Ephedrus species morphologically related to E. validus, with a reticulated propodeum, petiole, and densely pubescent ovipositor sheaths, features which imply that it is another species of root aphid parasitoids within the genus Ephedrus. Long notaulices along the mesoscutum represent a plesiomorphic character absent in almost all other congeneric species, except in E. validus and sometimes E. persicae where they remain shorter, maximally reaching the first third of the mesoscutum. This was confirmed by examination of several available specimens of E. validus, all of which possessed shorter notaulices (Fig. 3A). All these specimens share almost the same cytochrome c oxidase subunit I (COI) gene barcoding sequences (Kocić et al. 2019).

Discussion
Possession of 11-segmented antennae in both sexes represents a plesiomorphic character state in Ephedrus. Gärdenfors (1986) mentioned that in some "extremely rare" cases some specimens can possess 12-segmented antennae. However, in communication with the author (Gärdenfors, personal communication), we were informed that 12-segmented antennae are present only in specimens where terminal segments are elongated and semi-divided due to developmental instability of these individuals. We also found specimens with the terminal 10 th segment elongated and undivided (e.g., aberrant specimens of E. laevicollis (Thomson, 1895)). However, with clearly 12-segmented antennae, our Russian specimen of Ephedrus that was discovered in the Biologiezentrum Linz´s collection changes diagnostic characters for the genus Ephedrus (from 11-segmented antennae to 11-12-segmented antennae). Possession of 12-segmented antennae represents an apomorphic and very unusual character that was until now unknown for the genus Ephedrus. On the basis of the short fore wing 3SR vein, it can be concluded that E. antennalis sp. nov. belongs to subgenus Fovephedrus Chen, 1986 (recently revised by Kocić et al. 2019) and "persicae" species group. For details of diagnosis and biology, see Gärdenfors (1986), Žikić et al. (2009) and Kocić et al. 2019.
The phylogenetic position of the two species newly described here is unclear and integrative research on them in the future could provide insight about their taxonomic and phylogenetic status and suggest a possible subtribal classification of the genus Ephedrus.
Martin Schwarz from the Biologiezentrum (Linz, Austria) for providing the Ephedrus specimens from the museum collection.