An international team of researchers has announced the discovery of a new species of harvester ant, officially named Messor odrysarum. The discovery was made by researchers Albena Lapeva-Gjonova of Sofia University in Bulgaria and Lech Borowiec of the University of Wrocław in Poland.
The findings were recently published in the scientific journal ZooKeys and bring the total number of recognized Messor ant species in Bulgaria to nine.
A Nod to Ancient History
The newly identified ant is part of the Messor genus, a group well-known for their ecological role as grain and seed collectors in arid and semi-arid environments. The researchers chose the specific name "odrysarum" to honor the ancient Thracian state of Odrysia (roughly founded in early 5th century BC), whose historical geographical borders included the region where this new species was found.
Habitat and Behavior
Messor odrysarum is a lowland species that has been documented at elevations up to 647 meters in the Eastern Rhodopes region of Bulgaria. Researchers discovered their nests situated along dirt roads within oak forests and open grasslands. The nest entrances are built at ground level and “in late summer, seed remains were observed near the nest entrances”.
“Messor odrysarum is currently only known from the Eastern Rhodopes in Bulgaria, possibly also occurring in the Thracian region of Greece and Türkiye,” explain the researchers in their article.
Distinct Physical Characteristics
Confirmed through both rigorous morphological analysis and modern COI DNA barcoding, Messor odrysarum belongs to the Messor structor species group. While it is closely related to the known Balkan-Anatolian species Messor oertzeni, there are several distinctive physical traits that make the newly discovered ant stand out. It has a smaller overall body size compared to its close relatives and it is accented only by reddish hues on the lower genae (the cheek region of the head). It also has a narrowed head behind the eyes, longer and denser hairs (setae) on its head and midsection, and a longer antennal scape.
Scientific Significance
The formal description of Messor odrysarum helps to resolve ongoing taxonomic complexities within the Messor genus, which is known for cryptic diversity and remarkable reproductive strategies like hybridization or even xenoparity, where female gives birth to, or clones, offspring of a completely different species as part of its lifecycle. In addition to introducing the new species, the researchers' publication also provides a rare, updated redescription of the queen (gyne) caste of the related M. oertzeni based on newly collected specimens.
Original source
Lapeva-Gjonova A, Borowiec L (2026) A new species of Messor from Bulgaria and redescription of the gyne of M. oertzeni Forel, 1910 (Hymenoptera, Formicidae). ZooKeys 1275: 145-168. https://doi.org/10.3897/zookeys.1275.181745
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