Oxytripia orbiculosa (Esper, 1800) is a moth species in the subfamily Xyleninae (Noctuidae) with high intrapopulation variability, and most local colonies exhibit external differences. Zilli et al. (2005) noted that the variation between two nearby populations may be greater than that between specimens from the Balkans and Japan. In relation to its trans-Palaearctic distribution, two major geographical groups have been recognised, which have sometimes been given subspecific rank: the nominotypical subspecies, O. orbiculosa orbiculosa, which presents a wide but very patchy range from Germany to Japan in steppe areas and so-called ‘xerothermic’ grasslands, and the subspecies O. orbiculosa noctivolans Pinker, 1980, which inhabits xeromontane areas from Anatolia to the Tien Shan massif (Zilli et al. 2005) and beyond, reaching as far as Korea (GBIF 2026).

Across most of its range, Oxytripia orbiculosa is predominantly a xerophilous species, typical of steppes and plains, and it extends into semi-desert areas in both lowlands and mountains. It shows a preference for open or lightly shrubby habitats, especially grasslands and rocky or sandy slopes on calcareous soils (Zilli et al. 2005; Leraut 2019). Historically, the species was considered diurnal in the Carpathian Basin, with males flying during the day, although this behaviour has not been observed in other populations, which show a clear attraction to artificial light, and exhibit a fast, and erratic flight (Bolland 1982; Zilli et al. 2005). Males remain active throughout the night, while females usually appear in the second half of the night or at dawn (Zilli et al. 2005).

The larvae of Oxytripia orbiculosa live endophagously in the rhizomes of various Iris species. Schmidt (1913) associated the species with Iris pumila Lam. in loess soils, while Varga (1989), Fésüs et al. (1992), Mészáros and Szabóky (2010) and Țugulea and Rákosy (2021) linked it to Iris humilis Georgi (frequently referred to as Iris arenaria Waldst. and Kit.) in sandy steppe formations. This species overwinters in the egg stage, the larva completes its growth in July–August, and pupation occurs within the cavity created in the underground organs of the plant (Zilli et al. 2005). The flight period is autumnal, usually reported in October (Leraut 2019), although in the Pyrenees it has been found in mid-September at 1300 m (Bolland 1982).

In Europe, the species is scattered and local throughout its range, occurring from Central Europe to the southern Urals and the southern Balkans in a rather narrow zone along the major European mountain chains (Zilli et al. 2005; Leraut 2019). It has been recorded only once in the Spanish Pyrenees, at Canfranc (Huesca), by Bolland (1982). The species was erroneously reported from France on the basis of this record, which was misattributed to the French Basque Country (Robineau et al. 2007; D. Demerges, pers. comm.). Outside Europe, it is more widespread and common in parts of western and central Siberia and Mongolia (Zilli et al. 2005).

The aim of the present study is to confirm the reported distribution range of Oxytripia orbiculosa in the Pyrenees with new records, provide new data on its biology and genital morphology, and compare its DNA barcodes with those of Central European populations to test the hypothesis of the subspecific rank of the Pyrenean population.

The first sampling was carried out at Sagüeta Fort, in Aisa (Huesca), in the Spanish Central Pyrenees in September 2023 by Dave Grundy, using 2-watt LED traps placed in sheltered locations. In July 2024, during a field excursion, an abundance of Iris Tourn. ex L. species throughout the area was noted and, knowing that Oxytripia orbiculosa feeds on such plants, an attempt was made to extract bulbs from plants that appeared prematurely dry, a possible symptom of a noctuid larva feeding inside. Finally, in September 2025, ten traps with various types of light source, ranging from 2W LEDs and actinic or black light fluorescent tubes to conventional mercury vapour lamps, were placed directly in meadows located in different localities in the Central Pyrenees where Xiphion latifolium Mill. had been found a year earlier. The data regarding locality, altitude, MGRS coordinates, trap type and habitat are shown in Table 1, Fig. 1.

This study is based on the morphology of 11 adult moths that were examined externally to assess differences in their colour and wing pattern based on the taxonomic traits of Oxytripia provided by Zilli et al. (2005). Dissections (n = 5) were performed using a standard procedure (Yela 1992; Fibiger 1997) with minor modifications, and genitalia were mounted as permanent microscopic preparations in DMHF and Euparal. Image of the mounted adults (Fig. 2A, for one of them) were taken with a Nikon 7500D camera and z-stacked using Zerene Stacker software (Zerene Systems, Richland, Washington, USA), while a natural adult image (Fig. 2B) was taken with a Nikon Digital D7200 N1406 camera and a Nikon AF-S Micro Nikkor 105 mm 1:2.8 G ED lens. The morphology of the male genitalia (Fig. 2C) was studied using a Zeiss Stemi 508 stereomicroscope with a Zeiss Axiocam 208 digital camera. The abbreviation “g. prep.” refers to the number of genitalia preparations. Specimens are deposited in the Research Collection of Biología Animal (RCBAUM) in the Department of Zoology and Physical Anthropology of the University of Murcia and in the research collection of J. L. Yela, University of Castilla-La Mancha, Spain (JLY-UCLM).

The rediscovery of O. orbiculosa in the Pyrenees forty-three years after the first record published by Bolland (1982) is of great biogeographical relevance, as it confirms the existence of a colony isolated from the rest of the Central European populations. Unlike the lower elevation localities in southern Central Europe, O. orbiculosa isolata has been found at altitudes ranging from 1,400 m to almost 1,700 m in the Central Pyrenees.

Regarding its behaviour to light attraction, the species did not show a preference for a specific type of light; instead, it responded to various light sources.

The localities where the species was collected or observed, shown as positive records in Table 1, are open mountain meadows, while it was absent (negative records in Table 1) at sampling points with different habitats, such as riparian vegetation and riverside grasslands, pastures surrounded by coniferous forest and Atlantic temperate deciduous forest. This may be due to preferences of the moth to particular types of landscape or to differences in trap attractiveness related to surrounding vegetation height, or even to predominant wind effect.

Nevertheless, habitat selection appears to play a role in determining the presence of the species. During a field excursion in July 2024, we noted an abundance of a Xiphion species (Iridaceae) throughout the area. Knowing that O. orbiculosa feeds on Iridaceae (Schmidt, 1913), we attempted to extract bulbs from plants that appeared prematurely dry, a possible symptom of a noctuid larva feeding inside. After several unsuccessful attempts, we decided to return in search of adults in September, which was finally achieved in 2025. Although various species of the genus Iris, such as Iris pumila (Schmidt 1913) and Iris humilis (Varga 1989; Fésüs et al. 1992; Mészáros and Szabóky 2010; Țugulea and Rákosy 2021) have been mentioned as larval host plants for O. orbiculosa, in the central Pyrenees of Huesca the relationship is established with Xiphion latifolium Mill., previously known as Iris latifolia (Mill.) Voss (Fig. 2D). This orophilous plant endemism grows in high mountain pastures of the Pyrenees between 900 and 2400 m, in the Cantabrian Mountains from high elevations down to sea level, and scarcely at high elevation in the Central and Iberian systems (Castroviejo, 2013). This liliaceous plant grows mainly in high mountain meadows, in both sheltered and sunny areas, and more rarely in grazed clearings of pine, beech, or oak forests, as well as on roadsides and stony soils of varying natures that are not excessively dry. It possesses a bulb of 20–70 × 15–60 mm covered in frayed brown tunics; X. latifolium dries out in late summer and autumn, resprouting in spring (Castroviejo, 2013). The relationship between O. orbiculosa and X. latifolium means that this noctuid is primarily present in high mountain meadows within the montane and subalpine bioclimatic belts described by Rivas-Martínez (2007); therefore, the bionomic character of the Pyrenean population should be regarded as mesophilous, rather than xerophilous. Moreover, the abundance of X. latifolium in other areas of the Spanish Pyrenees suggests that O. orbiculosa may be much more widespread in localities that have not yet been adequately surveyed as well as on the northern slope of the Pyrenees (Pyrénées-Atlantiques). Given the distribution of the host plant in the mountain ranges of northern Iberia, it would be interesting to continue sampling to determine the presence of this species in high mountain meadows.

Genetically, the species is characterised by Barcode Index Number (BIN) BOLD:ABX1067 (n = 8). Iberian specimens are separated from specimens from Eastern Europe and Central Asia by a mean pairwise divergence in COI-5P ranging from 0.6% to 0.8%. This represents a considerable distance, given that, according to available data, populations from Eastern Europe and Western Asia are separated from each other by a mean pairwise divergence of 0.3%, although a single individual from Kazakhstan is separated from the rest of the European sample by 0.6% (Fig. 3). This suggests that the variability of Palearctic populations and what it means taxonomically requires further attention.