We report new oribatid records from the western Antarctic Peninsula region obtained during the XXVI–XXVIII Ukrainian Antarctic expeditions. Five species (including 2 subspecies) representing five families of oribatid mites were recorded: Nanhermannia elegantissima, Hermanniella dolosa, Membranoppia loxolineata, Suctobelbella sinuata, Alaskozetes antarcticus subsp. antarcticus and A. a. subsp. intermedius. The single specimen records of N. elegantissima, H. dolosa and S. sinuata are the first for these species in the Antarctic region. Hermanniella dolosa, previously recorded only in the Palearctic is likely to represent an anthropogenic introduction or contaminant. The other two species have been recorded from Southern Hemisphere locations, but far from the maritime Antarctic and their status cannot be assessed with confidence. Membranoppia loxolineata and the two subspecies of A. antarcticus were previously recorded from the maritime Antarctic, and we provide new specific occurrence records of these taxa. Our data expand knowledge of the distribution and biogeography of oribatid mites in the maritime Antarctic. Further research is required to assess the status of the three new species records and if established, any potential to impact the native microarthropod community.

Alaskozetes antarcticus, Hermanniella dolosa, Membranoppia loxolineata, Nanhermannia elegantissima, non-native species, Suctobelbella sinuata

Oribatida is a suborder of mites belonging to the order Sarcoptiformes within the superorder Acariformes of the subclass Acari (Krantz and Walter 2009). The known global diversity of oribatid mites includes more than 11,600 species representing 1,328 genera and 166 families. Of these, around 148 taxa are known from Antarctica (~100 species) and the sub-Antarctic islands (~54 species) (Pugh 1993; Subías 2004, 2021). The oribatid mite diversity of the maritime Antarctic (Antarctic Peninsula region and South Shetland Islands) currently includes 14 species and three subspecies (Wallwork 1973; Usher and Edwards 1986; Block and Starý 1996; Starý and Block 1998; Pugh and Convey 2000; Marshall and Convey 2002). These include Liochthonius australis Covarrubias, 1968, L. mollis (Hammer, 1958), Membranoppia loxolineata (Wallwork, 1965), Austroppia crozetensis (Richters, 1908), Brachioppiella pepitensis (Hammer, 1962), B. p. subsp. brevipectinata (Covarrubias, 1968), Alaskozetes antarcticus (Michael, 1903), A. a. subsp. intermedius Wallwork, 1967, Halozetes belgicae (Michael, 1903), H. b. subsp. longisetae Wallwork, 1967, H. impeditus Niedbala, 1986, H. marinus (Lohmann, 1907), H. necrophagus Wallwork, 1967, Totobates nordenskjoeldi (Trägårdh, 1907), Edwardzetes dentifer Hammer, 1962, Magellozetes antarcticus (Michael, 1895) and M. processus Hammer, 1962.

The first studies of oribatids in Antarctica took place at the end of the 19^th century and research continues to the present day (Michael 1895; Gwiazdowicz et al. 2022; Pfingstl et al. 2024). The current study reports new records of oribatid mites in parts of the maritime Antarctic, specifically the South Shetland Islands, Graham Coast and Argentine Islands, obtained during the XXVI – XXVIII Ukrainian Antarctic expeditions between 2022 and 2024. Five species (including two subspecies) representing five families of oribatid mites were recorded: Nanhermannia elegantissima Hammer, 1958, Hermanniella dolosa Grandjean, 1931, Suctobelbella sinuata (Hammer, 1982), M. loxolineata, A. antarcticus subsp. antarcticus and A. a. subsp. intermedius. Given current trends in climate change in the studied region (Convey 2003), studies recording the current state of biodiversity are very important.

We obtained mite specimens from four regions within the maritime Antarctic: (I) the Argentine Islands and Hovgaard Island (Wilhelm Archipelago); Here, substrates for extraction were obtained from the following islands: Hovgaard (bryophyte mat and carpet subformation of W. fontinaliopsis; Stercorarius maccormicki nest material, mainly Sanionia sp.), Irizar (moss turf subformation of Bryum sp.; bryophyte mat and carpet subformation of Sanionia sp.), Eight (bryophyte mat and carpet subformation of Sanionia sp.; moss turf subformation of Bryum sp.), an un-named island within the Barchans (Prasiola crispa (Lightfoot) Kützing community with Sanionia sp.), Eastern (L. dominicanus nest material, mainly Sanionia sp.) and Central (L. dominicanus nest material, mainly Sanionia sp.) of the Three Little Pigs Islands, Uruguay (algal subformation of P. crispa), Galindez (moss turf subformation of Polytrichum strictum), Skua (S. maccormicki nest material, mosses P. strictum and Sanionia sp.) and Lahille Island (mosses on a rock slope, mainly Andreaea sp., with the addition of Sanionia sp., Pohlia sp., and grass, Deschampsia antarctica). (II) Lahille Island (~32 km south of the Ukrainian Akademik Vernadsky Station); (III) Nelson Island (South Shetland Islands) (bryophyte mat and carpet subformation of Warnstorfia sp. and Sanionia sp.); and (IV) an un-named island (coordinates: -65.400171, -65.302682) within the Pitt Islands (bryophyte mat and carpet subformation of Sanionia sp.) (Fig. 1).

Figure 1. 

Sampling locations: A. General map of all study sites; B. Higher resolution view of the Argentine Islands region. Red spots represent sampling locations and red square indicating enlarged map area.

Mites were extracted from samples using a Berlese–Tullgren funnel (Walter and Krantz 2009) directly into 96% ethanol. Subsequent examination took place using light microscopy after the return of the extracted samples to the Center “Pedobiology” of the National Academy of Sciences of Ukraine. Oribatid mites were initially separated using an Olympus SZX10 stereomicroscope (Japan). Detailed examination for species identification was then performed under an Olympus BX51 light microscope (Japan) with reference to appropriate taxonomic keys (Wallwork 1965, 1967; Hammer 1982; Balogh and Balogh 1988; Weigmann 2006; Subías et al. 2021). A total of 123 individual oribatid mites were obtained. The taxonomic system follows the Integrated Taxonomic Information System (ITIS 2024).

Five oribatid mite species (including two subspecies) representing five families were identified amongst the specimens collected. Below, we provide a formal list of these species and information about their wider geographical distribution, habitats and other notes of interest.

In an era of climate change, which is widely predicted to lead to changes in species distributions including the colonization and establishment of species currently not present within given regions, the collection of robust baseline biodiversity data and ongoing monitoring of key locations are of fundamental importance. This is particularly the case in the Antarctic region, considered to be vulnerable to biological invasions and where, as yet, there have been relatively fewer instances of non-native species establishment (Hughes et al. 2015, 2024; Convey and Peck 2019). At present, no non-native species of oribatid mites are known to be established in the maritime or continental Antarctic regions (Hughes et al. 2015). However, some members of the group are known to have extremely well-developed tolerance to cold, desiccation and salinity stresses, with some species specifically occurring in littoral and supralittoral habitats and tolerating long-term submersion in seawater, while some can be dispersed by birds (Block and Convey 1995; Marshall and Convey 2002; Majka et al. 2007; Gwiazdowicz et al. 2022; Grewling et al. 2023).

The three ‘new records’ presented here of species not previously known from the Antarctic are all single specimens from different islands, and all appear most plausibly to represent either contaminants or association with anthropogenic activity. However, it is impossible to exclude natural dispersal events. Nevertheless, we emphasize that further detailed and targeted survey work is now required focusing on the specific collection locations from which specimens were noted here (cf. Hughes et al. 2017), in order to confirm the status of these species. If presence were to be confirmed, it would be important to assess local population size and distribution and confirm life cycle completion, as well as document the ecophysiological potential of the species, although the latter would require significant numbers of living individuals. The occurrence of one of these species, N. elegantissima, could potentially be explained by the long-standing operational and logistic (and, more recently, tourism) connection between the Falkland Islands (where it is known to occur; Starý and Block 1998; Subías 2004) and the operational Faraday research station established in the Argentine Islands in the mid-1940s. The record of S. sinuata, otherwise primarily a tropical or subtropical species (Hawaii, Bali) appears most plausibly to be an anthropogenically associated event. Although Subías (2004) lists the species from Amsterdam Island in the Indian Ocean, an island that is included in listings of ‘peri-Antarctic’ islands (Selkirk 2007), this island (like Tristan da Cunha in the Atlantic Ocean) lies at a subtropical latitude and experiences a warm temperate climate. None of the species’ occurrence locations have a plausible link with the western Antarctic Peninsula region. H. dolosa, native to the Palaearctic region (Subías 2004; Hushtan et al. 2021), seems most likely to be a contaminant.

Considerable increases in both national operator and tourism activity have taken place in the maritime Antarctic region in the latter part of the 20^th and early 21^st centuries (Tin et al. 2009; Convey and Peck 2019; Chwedorzewska et al. 2020). Any human presence in this region carries a risk of movement of both non-native and native species (Chown et al. 2012; Hughes et al. 2020), although confirmed species establishment events known to date can virtually all be most plausibly linked with national operations (Siegert et al. 2023; Hughes et al. 2024). Ongoing baseline survey and monitoring of Antarctic terrestrial biota, both in locations of high visitor pressure and in less visited and protected locations, are required to detect changes and design management actions. Detailed and common-sense biosecurity guidelines already exist (COMNAP and SCAR 2019) and must be rigorously and consistently applied by all operators and visitors.

M. loxolineata and A. antarcticus are species known to occur in the Maritime Antarctic region (Wallwork 1965, 1967; Pugh 1993; Subías 2004). The records of the former presented here are the first formal records for Lahille Island and the Argentine Islands. While relatively few studies have specifically recorded the smaller species of Oppiidae, M. loxolineata has been recorded as far south as Marguerite Bay (Usher and Edwards 1986; Convey and Smith 1997). Alaskozetes antarcticus, the largest micro-arthropod in Antarctica, is widespread and abundant throughout the Maritime Antarctic (Antarctic Peninsula and Scotia Arc archipelagoes) and extends into the sub-Antarctic. While our survey recorded two of the described sub-species of A. antarcticus, their presence in exactly the same substrates and locations can raise questions about the biological validity of this distinction, which has not as yet been addressed in molecular phylogenetic studies.

The specimens obtained in this study represent five species (including two subspecies) and families of oribatid mites. Single specimens of Nanhermannia elegantissima, Hermanniella dolosa and Suctobelbella sinuata provide the first records of these species in the Antarctic region, although they do not confirm establishment and seem most plausibly related to contamination (H. dolosa) or, possibly, historical logistic or other anthropogenic links leading to inadvertent introduction (S. sinuata, N. elegantissima). Further survey is required to confirm their status. Increasing national operator and tourism activity in the Maritime Antarctic emphasizes the need for robust surveys and ongoing monitoring of key terrestrial locations.

We are grateful to Dr. Ivan Parnikoza, State Institution National Antarctic Scientific Center, Kyiv, Ukraine for providing samples.

H.H.: conceptualization, identification of mites, interpretation, writing; K.H.: preparation of mite specimens for identification, writing; P.K.: sample collection, visualization; A.P.: sample collection; P.C.: interpretation and writing; I.K.: coordination of research. All authors contributed to the writing and editing of the manuscript.

The current study was performed in the framework of the Ukrainian State Special-Purpose Research Program in Antarctica for 2011–2025. P.K. takes part in a scientific research project of the National Academy of Sciences of Ukraine “Ecological indication of biotopes conditions using model biota representatives under anthropogenic transformation of ecosystems”. P.C. is supported by NERC core funding to the BAS ‘Biodiversity, Evolution and Adaptation’ Team.

The authors declare that they have no conflict of interest.