Some ants have morphologically distinct subcastes among workers, divided into minor workers, which are smaller, and major workers, which are larger and often have enlarged heads. Minor workers perform general tasks, while major workers often have more specialized roles, such as nest defense and nutritional storage. In addition to morphological caste differences, age plays an important role in polyethism. Generally, young workers having high fat mass become nurses, while old workers with reduced fat mass shift to foragers. However, few studies have examined the relationship between subcaste and age-dependent division of labor, and associated physiological changes. In this study, we used Camponotus yamaokai, which exhibits clear dimorphism among workers, to clarify the specialized roles of major workers in terms of behavior and physiology. We found that major workers rarely forage or leave the nest but instead defend the nest by plugging the nest entrance when heterospecific competitors are present in the feeding area. In histological observation of the lipid storage organ (i.e. fat body), minor workers showed a reduction in fat body size with aging, the typical of worker age-dependent changes. On the other hand, physiological changes with aging were minimal in major workers. These findings indicate that major workers of C. yamaokai maintain a stable, `young' physiological state and are specialized for intranidal nest defense, rarely shifting to extranidal tasks with age.
Republic of Korea (South Korea) lies between the Eurasian continent and the Japanese archipelago and spans temperate to subtropical climates. The geographic position of South Korea provides a biogeographic bridge that promotes high ant diversity. Recent taxonomic revisions are, however, generally lacking, and North Korean records are often merged uncritically with those of South Korea, underscoring the need for a comprehensive update. In this study, we provide an updated checklist of the ants of South Korea based on extensive field collections, critical examination of museum specimens, and a comprehensive review of published records. We recognize 147 valid species belonging to 44 genera in South Korea, with 22 species reported here for the first time. The updated list also recognizes six endemic species and thirteen non-native species, five of which are newly confirmed in South Korea (Monomorium carbonarium (Smi@ 1858), Nylanderia sp. cf. jaegerskioeldi (Mayr, 1904), Pheidole parva Mayr, 1865, Technomyrmex vitiensis Mann, 1921, and Tetramorium lanuginosum Mayr, 1870). Based on the literature and museum investigations, we also remove 31 species previously reported from South Korea. In addition, we present morphological descriptions and ecological information for the newly reported species and Camponotus dorex Fisher, 2025, a South Korean endemic with previously limited information. The checklist also identifies five dubious species and provides revised taxonomic treatments of problematic taxa, notably designatingAphaenogaster schmidti Karavaiev, 1912 as a nomen dubium. We further discuss distribution patterns, highlight ecological features such as endemism and potential future discoveries, and assess the current status and risks of introduced ants. This work offers the most comprehensive and up-to-date framework for understanding the diversity, distribution, and conservation priorities of South Korean ants.
Leptamlline ants are cryptic, and our comprehension of their natural history remains incomplete. We collected one colony of Leptanilla kubotai in October 2023 and investigated the colony composition and behavioral characteristics of this rare species. The nest of Leptanilla kubotai was situated 15 cm deep in the soil and contained one dichthadiiform queen, 453 workers, and 663 larvae. The queen had 88 ovarioles, while the workers had no ovaries. Workers were specialized predators of geophilomorph centipedes, and promptly recruited nestmates upon encounter with a prey. Larvae showed remarkable mobility, associated with unique morphological features: a ventral hooked claw on their prothorax and a row of teeth on the external margin of their mandibles. The queen and workers performed larval hemolymph feeding and likely rely on larvae for nutrition in the absence of prey. We compare these findings to other Leptanillinae and discuss the specialization of Leptanilla for a subterranean lifestyle.
Protective mutualism between ants and Macaranga genus plants ranges from obligate to facultative interactions. Unlike obligate ant-plant interactions, facultative mutualists like Macaranga tanarius lack specialized structures to house ant symbiont colonies but offer food rewards such as extrafloral nectary secretions and food bodies. These rewards attract opportunistic foraging ants that provide defense against insect herbivores. We hypothesized that the efficacy of this defense depended on the composition of the ant species. We assessed insect herbivory by recording leaf damage and monitored ant activity at different times of the day. We also conducted behavioral assays to test ants' response toward offered wax-moth larvae prey (representing lepidoptera larva that causes most leaf-loss damage of M. tanarius). Ant community composition did not differ between day and dusk, with almost half of the species (48.4%) active at both times. Saplings with foraging ants showed a trend of higher leaf loss (mean = 2.13%) than saplings without ants (mean = 1.32%), contrary to our expectations, although this difference was not statistically significant. This could be due to the short observation time in this study, as herbivore attacks on leaf loss may be accumulated over a longer period. Most ant visitors on M. tanarius, which relied on herbivory diets, ignored the prey items; only the yellow crazy ant Anoplolepis gracillipes consistently attacked offered prey. Future research should be carried out over a longer period, and the abundance of ant species patrolling M. tanarius should be recorded to understand the potential roles of ants on these plants.
Hainan Province is a tropical island identified as a global biodiversity hotspot, but limited sampling and taxonomic efforts have been conducted to catalog and describe its ant fauna. Here, we compiled valid historical records and new records based on past and recent ant surveys, to present the first checklist of ants specific to Hainan. In total, we identified 10 subfamilies, 67 genera, and 237 species, a 60% increase in the previous species checklist. A total 25 genera and 89 nominal species are newly recorded for the island, and 109 morphospecies are detected. The checklist also includes 15 exotic species, among which Pheidole megacephala (Fabricius, 1793) and Solenopsis invicta Buren, 1972 can be considered as invasive. Despite this update, we provide several lines of evidence to argue that the Hainan ant fauna remains largely understudied. Together, these findings not only highlight the rich biodiversity present but also the importance of increasing the species cataloguing rate and taxonomic work for the island. The use of additional sampling approaches, and new surveys targeting a wider geographic and ecological span might represent an efficient approach to fill this knowledge gap.
MostAcanthomyrmex ants have a granivorous diet, supplemented with other invertebrates and sugars. They are characterized by dimorphic workers, with major workers having substantially larger head width than minor workers. In this study, we investigated the colony composition and behavioral characteristics of both the queen and worker castes in Acanthomyrmex concavus Moffett, 1986, collected in Sabah, Borneo Island, Malaysia. All colonies had one or two ergatoid queens that exhibited an intermediate morphology between major and minor workers. Colony size was small, ranging from nine to thirty-seven minor and one to three major workers. Consistent with other species of Acanthomyrmex, A. concavus fed on tiny seeds (Ficus and Oxalis), and major workers played a crucial role in seed cracking. We discuss the possible selective pressures linking gramvory to ergatoid queen evolution in this genus, where more than half of the species have ergatoid queens.
A list of ants from Uzbekistan, based on a comprehensive analysis of scientific literature, long-term collections, as well as analysis of online databases (AntWeb and GABI), is presented. The checklist includes 114 species and subspecies from 31 genera and six subfamilies. Three species are recorded here for the first time. These are Tetramorium concaviceps (Radchenko, 1992), previously known from Kazakhstan and Mongolia, Formica mesasiatica Dlussky, 1964, recorded in Kazakhstan, Kyrgyzstan, China, and Mongolia, and the exotic species Hypoponera punctatissima (Roger, 1859). This work is the result of literature review and collection of material throughout Uzbekistan since 2010.
. In this article, a new species, Polyrhachis zhoui sp. nov., of the subgenus Myrmothrinax, is described based on worker and gyne specimens collected in Guangdong and Hainan Provinces, China. This new species belongs to the P. aequalis-group, for which an updated key is provided. The present record significantly increases the known distribution range of this species group to the north, especially within the Indochinese subregion, supporting recent research trends demonstrating that many species await discovery in the southern regions of China. This finding contributes to an increase in the total number of Polyrhachis ant species recorded in China to 56.
The ants of genus Syscia, are cryptic with an unequal distribution in Asia and the Americas; Currently, there are 34 species known in the New World, but only a mere 10 species are recognized in Asia. The New World species have been systematized, whereas Old World species are currently still at the stage of isolated species descriptions. Herewith a new species, namely Syscia chinensis sp. nov., is described and illustrated based on the worker caste. S. chinensis is the first species reported with 10-segmented antennae in this genus, and it is also one of the smallest minority species in this genus. These two characteristics readily distinguish the new species, and these morphological differences are supported by a phylogenetic analysis. A key based on the worker caste is provided for the known Asian species.
. In this study, we update the taxonomy of the ant genus Cerapachys in China. A recent survey of the leaf litter ant fauna in the Hengduan Mountains yielded a hitherto unknown species of Cerapachys, which we describe here as Cerapachys zhengyangwangi sp. nov. This new species is clearly distinguishable from all the other species in the genus. We provide an updated identification key of the genus Cerapachys based on the worker caste, as well as a diagnostic discussion and highquality specimen images.
Aenictus kodaguensis sp. nov., a new species belonging to the Aenictus pachycerus species group, is described from India based on the worker caste. This species is morphologically most similar to A. paradentatus Jaitrong & Yamane, 2012. However, it is distinguishable by the presence of a distinct transverse canna along the lateral mesosoma and a comparatively shorter scape, among other discernible characteristics. Our study provides a detailed discussion of its morphology and characteristics that distinguish this species from its closely related species.
Two new species of Syscia and one new species of Ooceraea (Hymenoptera, Formicidae) are described from Sabah, Borneo, East Malaysia. The queens available for two species of Syscia, and the male of one Syscia species are described. The brachypterous queen of S. yekzoeae has large eyes, a complete set of ocelli, a normal female thorax, and vestigial wings with no closed cell. This represents the first record of a brachypterous Syscia queen from the Old World. A short note on the behavior of Syscia yekzoeae sp. nov. is presented based on observations of a laboratory colony.
Currently, seven species of Camponotus are known from Mongolia, with three belonging to the subgenus Camponotus and two belonging to each of the subgenera Myrmentoma and Tanaemyrmex. Two species, Camponotus (Myrmentoma) lameerei and C. (M.) quadrinotatus, are herein recorded as new to the Mongolian ant fauna. These species belong to the C . fallax group. The specimens of C. quadrinotatus from Mongolia well agreed with the Japanese specimens examined in structure, sculpture and pilosity, but had paler color pattern than in the latter. An identification key to the workers of the genus Camponotus known from Mongolia is provided. Currently, a total of 75 ant species are known from Mongolia.
Tapinoma onaele sp. nov. from the Kodagu region of the Western Ghats, India, is described as the fourth species in the Tapinoma lugubre species group. This species is morphologically close to Tapinoma himalaicum Bharti et al., 2013, as both have long scapes and deep and concave anteromedial clypeal margins. However, it differs from T. himalaicum in having a darker and brownish body, contrasting with a darker gaster, longer scapes, and the dorsal surface of the propodeum being convex and rising above the mesonotum. An identification key for workers of the Tapinoma lugubre species group is provided. Tapinoma onaele sp. nov. is crepuscular and nocturnal, ground-nesting, and forages in the leaf litter. The species was observed carrying seeds, insects, and tending scale insects (Hemiptera), suggesting it is generalist like other members of Tapinoma.
. Colony founding queens of the ant, Manica yessensis Azuma, 1955, forage outside the nest to retrieve insect prey. During colony foundation, they also lay trophic eggs in addition to reproductive eggs that give rise to larvae. Thus, colony foundation to produce the first workers in this species is based concurrently on retrieved prey and trophic eggs. Laboratory experiments were conducted to examine how these two types of nutrition function for maturation of the first workers. Thirty foundresses were divided into three groups that had different food regimens, and that were compared in regard to outcomes of brood production. The results suggest that trophic eggs are sufficient for larval cohorts to reach the final instar stage (4th instar), but further maturation requires additional food, which is supplied from outside the nest. Therefore, new queens of M. yessensis use a blended strategy with trophic egg production and prey retrieval.
. Ponera kohmoku is a species described in 1996 from Yaku-shima Island, and all known records to date have been limited to the southern portion of Japan. Here, new records of P. kohmoku are reported from Guangdong, Guangxi and Hong Kong in China, adding a fourth Ponera species to Hong Kong and Guangxi as well as the first nominal record of this genus to the Guangdong myrmecofauna. By integrating ecological information from past literature records of P. kohmoku with these new records from Southeast China, P. kohmoku is suggested to be a forest understory generalist in terms of habitat preference. The disjunct distribution of the species in southern Japan, Guangdong, Guangxi and Hong Kong raises the question about the biogeographic history of the species and the genus. Here, we propose and evaluate two hypotheses for such disjunct distribution: 1) the extinction of population from most parts of eastern mainland China, and 2) knowledge gap caused by the under sampling of cryptobiotic ants in mainland China.
Opamyrma hungvuong Yamane, Bui & Eguchi, 2008, represents the earliest branching extant leptanilline lineage, whose biology is largely unknown. Although preliminary and fragmentary, as we were only able to observe them for a short period of time between March 18-23, 2023, we report here the first observations on the biology of the species in captivity, focusing on their preying behavior on centipedes. We captured two colonies (possibly fragments, containing several or many alate and dealate queens and no immatures) and a solitary dealate queen of O. hungvuong in Pu Hoat Nature Reserve, Nghe An, Vietnam. We could not confirm whether the two colonies contained mated reproductive queens and whether the solitary dealate queen was mated. We observed their reactions by offering some centipedes and juliform millipedes. Individuals from the colonies ignored juvenile juliform millipedes but readily paralyzed a geophilomorph (Mecistocephalus sp.), a lithobiomorph (Lithobius sp.), and two juvenile scolopendromorph centipedes (Scolopocryptops sp.) by stinging. Not only workers but also alate and dealate queens in the colonies aggressively attacked the centipedes. However, they failed to hunt a linotaeniid geophilomorph centipede (Strigamia sp.); the ants were quickly killed probably due to the chemical defense of the centipede. The solitary dealate queen also readily paralyzed a juvenile Scolopocryptops by sophisticated hunting behavior. The workers and dealate queens of O. hungvuong showed eager (apparently hemolymph) licking behavior on the paralyzed Mecistocephalus centipede. Our observations indicate that O. hungvuong is well-adapted for preying on certain active centipedes, although their exact prey repertoire and degree of prey specialization remain uncertain. Some other notes on their habitat, ovariole number, venom apparatus, and unique metasomal habitus are provided. We also discuss the functional roles of some female caste morphologies of O. hungvuong in their centipede hunting.
Lordomyrma mewasinghi sp. nov. is described from the Western Ghats of India. The species is well distinguished from all its known congeners based on qualitative morphology. An iden-tification key to the known Indian species based on the worker caste is also provided.
A new species of the genus Stictoponera Mayr, 1887 is reported from India. Stictoponera lattkei sp. nov. is well differentiated from already described species of this genus. An updated identifica-tion key supplemented with digital images is provided for all known Indian species.
Two orphan colonies of Anochetus shohki were collected from Yonaguni Island, Oki-nawa, Japan. Alate queens emerged from one of the orphan colonies, which had cocoons at the time of field-sampling. These queens exhibited an enlarged pronotum, which is a trait typical of non-claustral foundresses. They shed their wings in a few days, and then started laying eggs 24 days later. These eggs eventually developed into workers. After some of these workers eclosed, dissections revealed that queens possessed well-developed ovaries with six ovarioles (3 + 3) and workers lacked ovaries. Spermathecae of these queens were empty, and no males emerged during the study period. These findings indicate that uninseminated dealate queens in A. shohki can produce workers via thelytokous parthenogenesis, at least in orphan colonies. This represents the first report of thelytoky not only in Anochetus but also in the Ponerini tribe, and it is the second such report in the Ponerinae subfamily.
