Taxonomic overview of Polymixis serpentina (Treitschke, 1825) species-group, with the description of a new species (Lepidoptera, Noctuidae, Xyleninae)

Abstract The taxa of the Polymixis serpentina (Treitschke, 1825) species-group are revised. The external and genital features of all known taxa and a new species, Polymixis ivanchiki sp. n. (Lebanon, Israel, Turkey and Iran) are described and illustrated. Polymixis serpentina iatnana Hacker, 1996, is treated here as a species distinct from Polymixis serpentina (stat. n.). A diagnostic comparison of the members of the species-group is provided; descriptions of the genitalia of Polymixis serpentina minoica Fibiger, 1992 and Polymixis iatnana are given for the first time.


Introduction
Polymixis Hübner, [1820] is a Palearctic genus of the subfamily Xyleninae. During the last thirty years several remarkable works have been published dealing with the taxonomic aspects of the genus (Beck 1996(Beck , 1999Ronkay et al. 2001). In the latest revisionary work (Witt and Ronkay 2011) P. serpentina is attributed to the subgenus Polymixis Hübner, [1820]. Actually, two insular subspecies are distinguished: P. serpentina minoica from Crete and P. serpentina iatnana from Cyprus; both were described based on external features only. The authors (Fibiger 1992;Hacker 1996) stated in the descriptions that the genitalia show no difference between the subspecies. The existing differences in genitalia structures of the three subspecies of P. serpentina are described and discussed in detail in the present paper.
The most conspicuous difference between the female genitalia of two species can be found in the shape of the antrum. The posterior (anal) margin of the antrum of P. ivanchiki has a very deep cleft, which reaches the middle of antrum, whereas P. serpentina has only a slight, shallow cleft.
Etymology. The new species named in honour of Ukrainian zoologists, Ivanchik Taisiya Semenivna (1937-2007) and Ivanchik Grigoriy Semenovich (1929-2011, teachers of Department of Zoology, Faculty of Biology, Yuriy Fedkovych Chernivtsi National University. Distribution. The species is distributed in the Near East (Israel, Lebanon, SW Iran) and the southern parts of Turkey (provinces Hatay and Urfa).  Male genitalia (Figs 13-20). A detailed description of genitalia of this taxon is given by Ronkay et al. (2001). To this text it is possible to add only some more details of the characteristic structure of the juxta. In the typical populations of P. serpentina serpentina from Croatia the juxta has a wide posterior extension and medial part has a posterolaterally directed lobe or lateral arm on each side without any serration.
Female genitalia . Described by Ronkay et al. (2001). In addition that description, it is worth highlighting the importance of the shape of the posterior margin of the antrum, which has only a slight, rounded concavity in the middle. This shape of antrum is characteristic for the P. serpentina serpentina populations from Croatia (type locality) and adjacent areas (Slovenia, Bulgaria) (Figs 28-30). Females from the more eastern areas (north and central Greece, central and south Turkey) have the posterior margin of antrum more deeply incised (Figs 31-36). It should be noted that the genitalia figure in Noctuidae Europaeae 5 (Fig. 141) shows the male genitalia of P. serpentina minoica, whereas Fig. 335 illustrates the female genitalia of the nominate subspecies.
Note. Moths from Rhodes Island have some slight differences in male genital structure; further studies on a larger sample of material are needed to clarify the taxonomic situation of this insular population. It is not impossible that this population represents another, as yet undescribed, subspecies of P. serpentina. Fibiger, 1992 http://species-id.net/wiki/Polymixis_serpentina_minoica Figs 5, 6
Male genitalia (Figs 21, 22). The genitalia of this taxon were not described in the original description. It was stated that there were no differences between the two subspecies. There are, however, some recognisable differences between the structure of the genitalia of the Cretan and the other populations of P. serpentina. The ground plan of the male genitalia of P. serpentina minoica and the nominotypical subspecies is the same, but the shape of the juxta is different and all parts of the posterior half of valvae are more massive, being more intensively sclerotized. The posterior extension of juxta is similar to that of P. serpentina serpentina, but its lateral arms are more elongated, slightly curved, and significantly more divergent from the basal plate. The valvae are wider, and the costa, triangular basal plate, and its extension, appear rough and massive due to their stronger sclerotization; P. s. serpentina has narrower valvae with all parts of their distal sections being finer and thinner. Female genitalia (Figs 37-39). The copulatory organ of ssp. minoica differ from those of the ssp. serpentina in the on average shallower concavity on the posterior margin of antrum.  (Figs 23, 24). The original description contains the following text about the genitalia structure: "Ohne Berücksichtigung der sowohl beim Männchen als auch beim Weibchen nahezu identischen Genitalstrukturen würde man sie für eine gut ausgeprägte Art betrachten". The genitalia of both sexes show, however, clearly visible differences, especially in shape of juxta and antrum. P. iatnana has a wide, shield-like juxta with a wide posterior extension and very small drop-like lateral arms.
Female genitalia (Figs 40, 41). The female genitalia are characterized by the very wide and shallow concavity on the posterior margin of the antrum, which extends from one lateral edge to the other, whereas this incision is in the middle of the posterior margin in the two other subspecies.