The Hemiptera are one of the most species-rich groups of insects on Earth, with approximately 45,000 described species worldwide, of which up to 9,000 are found in the Palaearctic biogeographic realm. Within Georgia, around 700 species of true bugs have been catalogued to date, a figure built largely on the foundational work of Zaitseva, whose numerous publications from the 1960s through the 1990s laid the groundwork for understanding the zoogeographic and faunistic diversity of bugs across various regions of the country. Despite this legacy, the insect fauna of Georgia remains incompletely surveyed, and the new records underscore how much basic documentation is still needed in a region where many species known from neighbouring territories had simply never been looked for or collected within Georgian borders.

The fieldwork that produced the new records was conducted at sites across Georgia, ranging from urban parks in Tbilisi to the arid steppes of Vashlovani National Park in the country’s southeast. Specimens were collected by hand and with sweep-nets, fixed in 96 percent ethanol, and stored in a freezer at minus 22 degrees Celsius to preserve tissue quality for DNA barcoding. The researchers identified the insects using a suite of taxonomic keys, and for seven of the fifteen species, identification was confirmed through sequencing of the cytochrome oxidase subunit I (COI) gene, a standard molecular marker for animal species discrimination. The resulting DNA barcodes were checked against the Barcode of Life Data System (BOLD), an international reference database, and submitted to that system, with several representing the first barcodes ever generated for their species.

The molecular component of the study proved particularly valuable for species whose identification through morphology alone might have been ambiguous. For Trypetimorpha occidentalis, collected in Dighomi park in Tbilisi, three barcodes were obtained with a maximum within-cluster p-distance of just 0.15 percent, and the nearest neighbour in BOLD was a specimen of the same species from Kazakhstan at a mean p-distance of 0.61 percent. For Dimorphopterus blissoides, a bug associated with common reeds, the single barcode generated represented the first for the species in BOLD, with the nearest neighbour being Dimorphopterus spinolae from Austria at a p-distance of 3.21 percent. Similarly, the barcodes for Tuponia mixticolor, collected near Kumisi lake on Tamarix plants, were the first submitted for that species, with the nearest neighbour in the database being a different genus entirely, Campylomma, at a mean p-distance of 5.96 percent.

Among the true bugs, the family Miridae — the plant bugs — contributed the largest number of new records, with four species documented for the first time in Georgia: Europiella decolor, Tuponia mixticolor, Deraeocoris ventralis, and Orthocephalus brevis. This is consistent with the Miridae’s status as the largest heteropteran family, with more than 11,100 described species worldwide. Europiella decolor, collected on Artemisia plants in steppe habitat near Tbilisi, has a distribution considered broadly Holarctic, extending from Western Europe to Western Asia. Deraeocoris ventralis, also collected on Artemisia, is regarded as Euro-Siberian, while Orthocephalus brevis, found in a meadow at Telovani east of Tbilisi, has a European-Caucasian-Siberian range. All four species had previously been reported from countries adjacent to Georgia, making their absence from the Georgian faunal list more a matter of insufficient sampling than genuine rarity.

The predatory bugs — members of the families Nabidae and Reduviidae — accounted for four of the new records. Alloeorhynchus flavipes, a damsel bug, was collected at three sites including Gori and Telovani, typically under rocks in heathland, steppe, and forest-edge habitats. Three species of assassin bugs (Reduviidae) were recorded: Holotrichius bergrothi, Reduvius ciliatus, and Oncocephalus squalidus, all found at Mijniskure in Vashlovani National Park. The record of Holotrichius bergrothi is particularly notable, as the species was previously considered a sub-Turanian endemic with records from southern European Russia, the European part of Kazakhstan, and Turkmenistan. The Georgian specimens, collected in macropterous form, represent the first documentation of this species anywhere in the Caucasus ecoregion, extending its known range considerably westward.

The remaining new records span several other families. Within the Pentatomidae, the stink bugs, Holcogaster fibulata was collected on tree trunks in deciduous forest and on pine in Tbilisi, with its barcodes matching specimens from France at a p-distance of just 0.31 percent. Vilpianus galii, found on Galium plants in steppe near Gori, is considered Mediterranean-Iranian-Turanian in distribution, and the researchers noted its distinctive jerky locomotion, unlike the fluid movement typical of most pentatomids. Within the Rhyparochromidae, the seed bugs, Pterotmetus staphyliniformis was collected under rocks in steppe near Gori, confirming a presence in Georgia that had previously been questioned in the literature, while Diomphalus hispidulus was found near the ground in semidesert at Chachuna Managed Reserve. Psacasta neglecta, a shield-backed bug in the family Scutellaridae, was collected under rocks in steppe near Gori, with its known food plants including Lappula squarrosa and various species of Echium and Anchusa.

Dimorphopterus blissoides, the reed-associated seed bug in the family Blissidae, offers a detailed picture of the ecological habits that characterise many of the newly recorded species. The species is distributed across the Ponto-Mediterranean region and is closely associated with common reeds (Phragmites australis), living in the sheaths of dry leaves and in the cavities of broken stems, where adults and older larvae hibernate. In spring, the bugs move to growing young shoots, gathering in groups of two to six or more in the sheaths of leaves at the preapical node or among semi-opened leaves at the top of shoots, where they remain until the end of their lives. The Georgian specimens were collected on Phragmites in Dighomi park in October 2021, consistent with the species’ known phenology and habitat preferences documented from neighbouring countries including Armenia, Azerbaijan, Turkey, and Russia.

The geographic patterns emerging from the new records are telling. Most of the fifteen species had previously been documented from territories immediately adjacent to Georgia — Turkey, Armenia, Azerbaijan, Iran, Iraq, and various regions of Russia — suggesting that the Caucasus region has been under-sampled rather than biologically distinct in ways that would exclude these insects. Trypetimorpha occidentalis, for instance, was previously reported from Turkey, Armenia, and Russia’s Rostov area, and is broadly distributed across the Palaearctic realm. Holcogaster fibulata, originally Holomediterranean, is currently spreading into central Europe. The presence of these species in Georgia fills gaps in distribution maps that have persisted largely because systematic insect surveys in the South Caucasus have been limited since the Soviet era, when much of the region’s entomological baseline was established.

The researchers anticipate that further targeted studies will reveal more new records for the Georgian fauna, given that most of the species documented here occur in adjacent territories and likely have broader distributions within the Caucasus than current records suggest. The CaBOL project, which combines traditional morphological taxonomy with DNA barcoding, represents a systematic effort to document the region’s biodiversity using modern molecular methods. The DNA barcodes generated during this study, along with the physical specimens deposited in the scientific collections of Ilia State University in Tbilisi, provide a permanent reference framework for future research. As the Caucasus continues to be recognised as a global biodiversity hotspot, studies like this one — documenting the precise composition of its insect fauna — contribute essential baseline data for conservation planning and for understanding how species distributions across the region reflect the complex interplay of Mediterranean, Turanian, and Siberian biogeographic influences.

Subject of Research: First records of fifteen Hemiptera species in Georgia

Article Title: First record of 15 species of Hemiptera ( Hexapoda , Insecta ) in Georgia

Article References: Chitadze, B., Bulbulashvili, N., Japaridze, L.-G., Drogvalenko, A., Moulet, P., & Seropian, A. (2024). First record of 15 species of Hemiptera (Hexapoda, Insecta) in Georgia. Caucasiana, 3, 127-143. https://doi.org/10.3897/caucasiana.3.e124994

Image Credits: AI Generated

DOI: 10.3897/caucasiana.3.e124994

Keywords: Hemiptera, Heteroptera, Auchenorrhyncha, Georgia, Caucasus, CaBOL, DNA barcoding, biodiversity, insect fauna, new records, Caucasiana, true bugs