Oenopia shirkuhensis sp. nov. (Coleoptera, Coccinellidae) is described and illustrated. It was found in the mountains around Shirkooh mountain, Yazd province, and in the Kukhbenan Mountains, Kerman province, Iran. It is similar to a common ladybird Adalia bipunctata by the colour pattern on elytra. Congeneric species occurring in Iran, O. conglobata and partly O. oncina are illustrated for comparison, and an identification key is provided.

ladybug, Müllerian mimicry, new species

Coccinellidae is a diverse beetle family well known and appreciated by the wide public mainly due to their attractive colour patterns with spots and stripes. The tribe Coccinellini, which includes now about 94 valid genera (Nedvěd 2015; Escalona et al. 2017), especially shows high interspecific and also intraspecific variability in elytral colour patterns. Groups of similarly coloured species of ladybirds seem to form Müllerian mimicry rings, where certain aposematic patterns are shared among sympatric species (Brakefield 1985). Polymorphic ladybird species, such as Adalia bipunctata (Linnaeus, 1758) and A. decempunctata (Linnaeus, 1758), have several forms that are members of different mimicry species rings.

Oenopia Mulsant, 1850 is a relatively species-rich genus of ladybirds with 21 species occurring in the Palearctic and Oriental regions (Iablokoff-Khnzorian 1982). There have been three species of Oenopia reported so far from Iran: O. conglobata (Linnaeus, 1758), O. montana Savoyskaya, 1969, and O. oncina (Olivier, 1808) (Abdolahi Mesbah et al. 2016).

Species of the genus Oenopia have a medium-sized body (2.5–6 mm), which is broadly oval to oval (length/width 1.25–1.5) and moderately convex. Antennae are as long as the width of the frons between eyes. Prosternal process bears carinae that do not reach anterior margin of prosternum. Shallow fovea in the middle of the anterior margin of mesoventrite bears the prosternal process (Fig. 5). Scutellum is 8–15×, epipleuron 6–12× narrower than body in their widest positions. Episterna and epimera of metathorax are black. Postcoxal line of the abdominal ventrite 1 is incomplete, either in the form of quarter of circle or divided into two parts, one parallel to the hind margin and one oblique. Tibial spurs are small, tarsal claws have basal tooth (except in O. montana). Distal part of penis is strongly narrowed, penis guide is wide, often bifurcated and with the tip bent upwards. The species are arboreal, aphidophagous.

We describe and illustrate a new species of Oenopia from high mountains of central Iran. It is compared to the common O. conglobata and to the unrelated A. bipunctata which have similar elytral colour pattern as the new species.

Morphological terminology follows Ślipiński (2007). Photographs were taken using a Nikon SMZ 1500 stereo microscope with Lumenera digital camera and QuickPhoto software. Composite images with deep focus were generated using Zerene stacker. Genitalia were dissected, boiled in 10% KOH, washed in water, alcohol, acetone, and xylene, then submerged to artificial resin on a microscopic slide. Photos of Oenopia conglobata were taken with Nikon D850 and handmade macro lens and processed with Zerene stacker.

The following measurements were taken: BL = total body length from clypeus to apex of elytra; BW = body width across both elytra at widest point; HW = head width including eyes; PL = pronotal length, from middle of anterior margin to base of pronotum; PW = pronotal width at widest point; EL = elytral length from the base including the scutellum to apex of the elytra.

The main morphological characteristics of the new species are very similar to the common and widespread Oenopia conglobata (Figs 11–17). The colour pattern of the new species superficially resembles A. bipunctata but may be derived from the pattern of O. conglobata, if only the pair of the largest spots is retained. The position of these spots on the elytra is more similar between the two Oenopia species than between O. shirkuhensis and A. bipunctata (Table 1). Oenopia conglobata varies in background colour (Figs 11, 12). This includes O. conglobata contaminata (Ménétriés, 1849) with pale pink (dominant) and pale red (less common) individuals (Zare Khormizi et al. 2016). Other Asian species of Oenopia possess much different elytral pattern and shape of genitalia (Figs 18, 19; Iablokoff-Khnzorian 1982). Thus, we hypothesize that O. conglobata and O. shirkuhensis are closely related species and that O. shirkuhensis speciated in the isolated environment of high mountains surrounded by deserts. We extracted DNA from two paratypes, but it was degraded, and no PCR product needed for identification and estimation of evolutionary distance between the two species was obtained.

Figures 18, 19. 

Oenopia oncina 18 tegmen, outer view. Single tip of penis guide pointed towards the viewer 19 tegmen, lateral view. The tip is inclined more than 90° from the plane of penis guide main body. Parameres slightly longer than the penis guide. Scale bars: 0.5 mm.

The new species was the only coccinellid species found at that high elevation (2960–3155 m a.s.l.) on the slopes of Shirkooh mountain (4055 m high). The nearest locality with other ladybirds was at the hillside at the beginning of the Sorgan valley (31°37.30'N, 54°05.97'E, 2760 m a.s.l.) There, the first author found four species of ladybirds on asafoetida plants (Ferula assa-foetida L., 1753): Hippodamia variegata (Goeze, 1777) (2 exx.), Coccinella septempunctata (Linnaeus, 1758) (1 ex.), Oenopia oncina (1 ex.), Scymnus subvillosus (Goeze, 1777) (1 ex.). Neither O. conglobata nor A. bipunctata were found nearby.

The striking similarity of O. shirkuhensis to A. bipunctata f. typica could be explained by Müllerian mimicry. O. shirkuhensis has 1) orange-red colour background and 2) only two black spots on elytra in similar position as A. bipunctata (but see exact positioning in Table 1). Both characters are apparently apomorphies, not found in other Oenopia species, except O. conglobata. However, living in an isolated alpine environment without presence of the putative model (A. bipunctata) brings to question Müllerian mimicry as a mechanism for the evolution of the colour pattern. As an opposite possible example of Müllerian mimicry, we (Nedvěd et al. in press) found individuals of A. bipunctata f. fasciatopunctata, with pink background unusual for the genus Adalia, living together with typical pink O. conglobata in Chaharmahal and Bakhtiary province. The new species possesses very light colouration even though it is advantageous to many insects to be dark in alpine habitats and thus use sunshine to heat up the body (e.g. compare with Maclean et al. 2016). Similarly, O. montana from mountains of Kazakhstan to Kirghizstan and O. signatella (Mulsant, 1850) from the Himalayas have very light colouration (Iablokoff-Khnzorian 1982).

Shirkooh mountain is one of the central mountains of Iran. According to the latest studies on Shirkooh mountain vegetation, 610 plant species have been identified and listed in the region (Irannezhad 2012), about 70% of the flora of Yazd province. This high diversity relative to the small area within the large province indicates the high plant species richness of the region. Of the 610 species, 91 have a special conservation value and are listed on the Red List of plants of Iran (Mathew et al. 2000). Thus, we expect also high number of invertebrates, including undescribed ones. The second locality of the new species in Kerman province is located 150 km from Shirkooh. Desert separates the two localities.

Photos of Oenopia conglobata were taken and processed by an expert photographer of insects, Soheil Shahbazi. The photo of O. shirkuhensis from Kerman province, collected by Yu. Skrylnik, was photographed by Alexander Slutsky (http://www.alsphotopage.com). The authors have no funding to report. The authors have declared that no competing interests exist.