Oxytripia orbiculosa (Esper, 1800) is a moth in the subfamily Xyleninae of the family Noctuidae, characterised by high intrapopulation variability. Zilli and colleagues noted in 2005 that variation between two nearby populations may be greater than that between specimens from the Balkans and Japan. The species has a trans-Palaearctic distribution, with two major geographical groups sometimes given subspecific rank: the nominotypical O. orbiculosa orbiculosa, which presents a wide but very patchy range from Germany to Japan in steppe areas and so-called xerothermic grasslands, and O. orbiculosa noctivolans Pinker, 1980, which inhabits xeromontane areas from Anatolia to the Tien Shan massif and beyond, reaching as far as Korea.

Across most of its range, O. orbiculosa is predominantly a xerophilous species, typical of steppes and plains, extending 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. 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, erratic flight. Males remain active throughout the night, while females usually appear in the second half of the night or at dawn.

The larvae of O. orbiculosa live endophagously in the rhizomes of various Iris species. Schmidt associated the species with Iris pumila in loess soils, while Varga, Fésüs and colleagues, Mészáros and Szabóky, and Țugulea and Rákosy linked it to Iris humilis in sandy steppe formations. The species overwinters in the egg stage, the larva completes its growth in July and August, and pupation occurs within the cavity created in the underground organs of the plant. The flight period is autumnal, usually reported in October, although in the Pyrenees it has been found in mid-September at 1,300 metres.

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. It has been recorded only once in the Spanish Pyrenees, at Canfranc (Huesca), by Bolland in 1982. The species was erroneously reported from France on the basis of this record, which was misattributed to the French Basque Country. Outside Europe, it is more widespread and common in parts of western and central Siberia and Mongolia.

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 species throughout the area was noted and, knowing that O. 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 had been found a year earlier.

The study is based on the morphology of 11 adult moths examined externally to assess differences in colour and wing pattern based on the taxonomic traits of Oxytripia provided by Zilli and colleagues. Dissections were performed using a standard procedure with minor modifications, and genitalia were mounted as permanent microscopic preparations in DMHF and Euparal. Images of the mounted adults were taken with a Nikon 7500D camera and z-stacked using Zerene Stacker software, while a natural adult image was taken with a Nikon Digital D7200 camera and a Nikon AF-S Micro Nikkor 105 mm lens. The morphology of the male genitalia was studied using a Zeiss Stemi 508 stereomicroscope with a Zeiss Axiocam 208 digital camera. 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.

For DNA extraction, two legs were removed from each of three specimens to sequence the 658 base-pair barcode segment of the mitochondrial COI gene. The tissue samples were sent to the Canadian Centre for DNA Barcoding following the protocol described in deWaard and colleagues. Sequences were compared with a reference library of Lepidoptera barcodes using the identification engine of BOLD. Voucher data, GPS coordinates, images, sequences and trace files of O. orbiculosa are available through the public data set in BOLD. Three Iberian samples were included, and the study was completed with eight publicly available samples downloaded from BOLD. COI sequences were aligned with the CLUSTAL algorithm of MEGA6 software and edited manually. Sequence divergences for the barcode region were calculated using the Kimura 2 Parameter algorithm including all sites with the pairwise deletion option. Finally, the number of haplotypes, haplotype diversity index, variable sites, nucleotide diversity index and G+C content were calculated with DnaSP v5.10, and the median-joining network of the haplotypes was constructed using PopART.

Specimens of O. orbiculosa are externally quite variable in both colour and size; variation is large both within and among populations. Nevertheless, examined Pyrenean specimens are on average markedly darker and larger (mean wingspan 38.0 mm; n = 5; all males) than the Central European ones, in a way similar to that described for Mongolian and Minusinskian specimens by Zilli and colleagues in comparison with Eastern Palaearctic populations. Whitish spots, markings and crosslines on the forewings are less apparent than in the vast majority of examined Eastern European specimens. No differences have been found in the genitalia relative to Central and Eastern European specimens. The wingspan of males ranges from 32.1 to 41.0 mm. Ground colour is blackish, characteristically dark. The basal line of the forewing is barely visible, if present at all. The antemedian line is generally indistinct, almost absent in some specimens. The basal part of the blackish strip on hindwing vein M1 is clearly discernible, and the thin blackish antemarginal line of the hindwings reaches the wing costa.

The rediscovery of O. orbiculosa in the Pyrenees forty-three years after the first record published by Bolland 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 metres to almost 1,700 metres 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 are open mountain meadows, while it was absent 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.

Although various species of the genus Iris, such as Iris pumila and Iris humilis, have been mentioned as larval host plants for O. orbiculosa, in the central Pyrenees of Huesca the relationship is established with Xiphion latifolium, previously known as Iris latifolia. This orophilous plant endemism grows in high mountain pastures of the Pyrenees between 900 and 2,400 metres, in the Cantabrian Mountains from high elevations down to sea level, and scarcely at high elevation in the Central and Iberian systems. 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. 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; 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. 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 BOLD:ABX1067. 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%. This suggests that the variability of Palearctic populations and what it means taxonomically requires further attention. The combination of biological, morphological and molecular data therefore reinforces the taxonomic identity of the Iberian population at the subspecific level, and the authors propose the name Oxytripia orbiculosa isolata Guerrero, Yela, Grundy, Rubio & Ortiz, 2026, ssp. nov.

Subject of Research: Taxonomy and Biogeography

Article Title: Isolated in the Pyrenees: Oxytripia orbiculosa isolata Guerrero, Grundy, Yela, Rubio & Ortiz, ssp. nov. based on biological, morphological and molecular data ( Lepidoptera , Noctuidae , Xyleninae )

Article References: Guerrero, J. J., Yela, J. L., Grundy, D., Rubio, R. M., & Ortiz, A. S. (2026). Isolated in the Pyrenees: Oxytripia orbiculosa isolata Guerrero, Grundy, Yela, Rubio & Ortiz, ssp. nov. based on biological, morphological and molecular data (Lepidoptera, Noctuidae, Xyleninae). Alpine Entomology, 10, 169-175. https://doi.org/10.3897/alpento.10.196677

Image Credits: AI Generated

DOI: 10.3897/alpento.10.196677

Keywords: Lepidoptera, Noctuidae, Xyleninae, Pyrenees, taxonomy, endemism, DNA barcoding, COI, Iridaceae, Xiphion latifolium, Isolated, Oxytripia