Aphaenogaster

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Aphaenogaster
Temporal range: 48.6–0 Ma Middle Eocene – Recent
Aphaenogaster umphreyi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Stenammini
Genus: Aphaenogaster
Mayr, 1853
Type species
Aphaenogaster sardoa
Diversity
218 species
14 fossil species
(Species Checklist, Species by Country)

Aphaenogaster umphreyi casent0103612 profile 1.jpg

Aphaenogaster umphreyi

Aphaenogaster umphreyi casent0103612 dorsal 1.jpg

Specimen Label

Synonyms

Aphaenogaster is one of the most species-rich genera of the subfamily Myrmicinae, comprising 218 described modern species as well as a number of subspecies. Its geographical range is quite peculiar. More than half of the known species are distributed in the western Palaearctic Region, of which over 100 occur in the Mediterranean; four species are known from Madagascar; around ten species are found in Australia, six in New Guinea, around 40 in Central Asia, south of the eastern Palaearctic, and in the Oriental Region, and only about 25 occur in Nearctic and Neotropical Regions, from southern Canada to northern Columbia. At the same time, Aphaenogaster is absent from southern South America and in the Afrotropical region (Radchenko & Perkovsky, 2016; Schifani et al., 2022). Its species inhabit relatively warm temperate deciduous forests, tropical forests, as well as various landscapes of the Mediterranean types, but are absent from steppes and deserts.

Aphaenogaster belongs to the tribe Stenammini (sensu Ward et al., 2015). The characteristic features of the tribe are the distribution of the vast majority of its representatives in the temperate zone of the northern hemisphere, and the evolution of many genera toward adaptation to granivory: five of the seven genera of the tribe are specialised harvesters inhabiting arid and semiarid landscapes (Bernard, 1967, 1974; Arnoldi, 1976; Collingwood, 1978; Dlussky, 1981; Tohmé G. & Tohmé H., 1981; Bolton, 1982; Collingwood & Agosti, 1996; Demarco & Cognato, 2015; Salata & Borowiec, 2015; Johnson et al., 2022). Among them, Goniomma and Oxyopomyrmex are Palaearctic endemics, Novomessor and Veromessor are Nearctic endemics, and in the predominantly Palaearctic genus Messor, only a small number of species are distributed in the arid regions of the Afrotropics, Arabian peninsula, Pakistan and India. At the same time, representatives of Stenamma inhabit mesophytous temperate and partly tropical forests, and Aphaenogaster species live both in temperate deciduous forests and in open semiarid landscapes.

Extant Aphaenogaster species are fairly diverse morphologically, which has led to the establishing of several subgenera in this genus, but all these names are considered now junior synonyms of Aphaenogaster. Branstetter et al. (2022) showed that Aphaenogaster in modern interpretation is a paraphyletic genus and is clearly divided into two clades: one includes Holarctic species form the former subgenera Attomyrma and Aphaenogaster s. str. + genus Messor, and the other, the “Deromyrma” clade, containing species from the former subgenera Deromyrma, Nystalomyrma and Planimyrma, distributed in Central America, Madagascar, New Guinea and Australia. [This section modified from Radchenko et al. (2024).]

Identification

Australian species

Antennae are 12 segmented (including the scape) with a 4 segmented club. In side view the propodeum is depressed below the level of the pronotum and forward (anterior) section of the mesonotum, these two regions being connected by the steeply sloping rear (posterior) section of the mesonotum. All workers from a nest are approximately the same size (monomorphic).

Aphaenogaster is most often confused with Pheidole or possibly Carebara. They can be separated from Pheidole by the 4 segmented rather than 3 segmented club and larger body size (over 3.4mm long), and from Carebara by the 12 segmented antennae (they are 11 segmented in Carebara). Additionally, both Pheidole and Carebara have major and minor workers (Pheidole is dimorphic, Carebara polymorphic) while Aphaenogaster has only a single worker caste (is monomorphic).

The Australian species of Aphaenogaster show differences which are little more than variation on a theme. This is in contrast to the nearby Papua New Guinea fauna where morphological variation is considerable. This difference suggests that the Australian fauna is composed of closely related species while that of PNG consists of several more distantly related lineages.

North American species

These ants can usually be easily distinguished by their elongate, slender habitus (general appearance). Their head is usually longer than broad, eye large, convex and placed at the middle of the head. The mesonotum of the worker is elongate and depressed, the propodeum usually has a pair of spines or small teeth. The workers could be confused with the minor workers of Pheidole, but differ in usually being much larger (over 3 mm total length, usually less than 3 mm in Pheidole), and that the antennal club is poorly defined and consists of four segments (well defined in Pheidole and usually consisting of three segments).

Vietnamese Species

Eguchi, Bui and Yamane (2011) - Worker monomorphic; head in full-face view oval or elliptical, often with extremely elongate neck; frontal carina, if distinct, not extending beyond the level of eye in full-face view; antennal scrobe absent; parafrontal ridge or carina(e) often present; median portion of clypeus convex anteriad, sometimes with a shallow emargination at midpoint; posteromedian portion of clypeus moderately or relatively broadly inserted between frontal lobes; masticatory margin with apical and 2 distinct preapical teeth followed by several smaller teeth or denticles; palp formula 5,3 or 4,3; antenna 12-segmented, gradually incrassate toward apex or with an indistinct 4-segmented club; eye medium sized; mesosoma elongate; promesonotum forming a dome; promesonotal suture weakly present or absent dorsally; metanotal groove moderately or strongly impressed dorsally; propodeal spines varying in size and shape (rarely reduced to tiny denticles or rounded angles); propodeal lobe round or subtriangular with blunt angles; petiole consisting of an anterior peduncle and a node (separation between peduncle and node sometimes indistinct); gastral shoulder absent.

The worker of Aphaenogaster is similar to the minor worker of Pheidole (larger species) and the worker of Kartidris and Myrmica. In the minor worker of Pheidole the masticatory margin of the mandible bears 1 or 2 small teeth between the preapical tooth and the 3rd large tooth. In the worker of Kartidris the vertex has a broad depressed area between eyes, the masticatory margin of the mandible has 5 distinct teeth, the antennal club is distinctly 3-segmented, and the propodeum is unarmed. In the worker of Myrmica the promesonotum is only slightly raised and the propodeal lobe is well-developed as a triangular or sharp lamella. In addition, the palp formula is always 6,4 in Myrmica as opposed to 5,3 or 4,3 in Aphaenogaster.

There are a number of Aphaenogaster species groups. These have mainly served as a convenience for organizing revisionary studies that focus on a morphologically similar set of species from a particular region: Aphaenogaster species groups

Species Complex

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Keys including this Genus

 

Keys to Species in this Genus

Distribution

Distribution is notably concentrated in the northern hemisphere. In the southern hemisphere, they are extremely sparse in the Neotropical and Afrotropical regions, although relatively rich in the Australian region.

Distribution and Richness based on AntMaps

Species by Region

Number of species within biogeographic regions, along with the total number of species for each region.

Afrotropical Region Australasian Region Indo-Australian Region Malagasy Region Nearctic Region Neotropical Region Oriental Region Palaearctic Region
Species 0 8 14 9 22 19 24 150
Total Species 2841 1736 3045 932 835 4379 1741 2862

Fossils

Fossils are known from: Baltic amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene), Bitterfeld amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene), Dominican amber, Dominican Republic (Burdigalian, Early Miocene), Enspel Formation, Rhineland-Palatinate, Germany (Oligocene), Florissant, Colorado, United States (Late Eocene), Mexican amber, Chiapas, Mexico (Middle Miocene), Quesnel, British Columbia, Canada (Early Miocene?), Rott, Westphalia, Germany (Late Oligocene), Rovno amber, Baltic Sea region, Europe (Priabonian, Late Eocene), Sakhalin amber, Ukraine (Thanetian, Paleocene), Zhangpu amber, Zhangpu County, Fujian Province, China (Miocene) (an unidentified species, Wang et al., 2021).

Biology


In this short observation a single worker drags a yellow jacket (Vespula spp.) until a point close to the nest and then switches task. She leaves to recruit more workers as a scout. Until the first recruits arrive two workers tend the prey. The location of the prey must be close to the nest because a third worker join them 55 seconds after the scout leaves. Based on the time stamp of the unedited footage 1 minutes 44 seconds after the scout leaves the number of workers around the prey already reaches four.

The most striking event is the flood of recruits flooding into the scene entering from the upper right corner of the screen one by one. The worker numbers reached 26 before the prey is moved once again towards the nest. During this time four ants returned back to nest perhaps to recruit more workers. Scientist studying ants call this behavior “task allocation”. Learn more.

Danum Valley, Sabah

Notes on Australian species: The distinctive nests of Australian Aphaenogaster ants are often the first indication of their presence. These nests can be very dense and when in sandy soils, individual entrances can be large, deep cones or bores (up to 4 cm in diameter and 30 cm deep) with large mounds of loose dirt. This style of nest has resulted in these ants being known as "funnel ants." In some cases nests can be so dense and extensive that they severely affect soil structure, resulting in a loose and fragile surface which easily collapses under foot. When this occurs in situations such as golf courses, pastures and unsealed airstrips damage can be severe and these ants can become a serious problem. Although not aggressive, workers will defend their nests when disturbed, emerging from entrances in small numbers to attack intruders.

While nests can contain large numbers of workers, few workers are usually seen on the surface, and then most are found near the entrance; they are rarely seen foraging any distance from nests. It is known that these ants tend aphids on the roots of plants and that arthropod fragments are often found in the upper portions of their nests. It is possible that the tended aphids provide much of the food needed by the nest, and that the funnel-shaped entrances act as traps for surface foraging arthropods. These factors may combine to reduce or eliminate the need to forage on the surface of the ground.

Notes on North American species: These are elongate, slender ants which are very fast and agile in the field. Most species nest in the soil under stones or logs while some of the desert species nest in the soil with the nest entrance surrounded by pebbles. They are carnivorous, and collect dead insects, as well as tend Homoptera or collect nectar. Colonies are moderately large to very large. This is a common genus and occurs in all habitats, but is especially common in forested ecosystems.

Notes on Vietnamese species: Eguchi, Bui and Yamane (2011) - The majority of species inhabit well-developed forests but some occur in sparse forests, dwarf forests and areas with low bushes. Nests are usually found in the soil, under stones and in rotting logs (Bui & Eguchi 2003, Eguchi et al. 2004).

Csősz et al. (2021): Across the distribution of Aphaenogaster in Madagascar, there are species of Camponotus that mimic the general form and behavior of Aphaenogaster: Camponotus imitator, Camponotus jodina, Camponotus karaha and Camponotus longicollis. These Camponotus mimics are often seen foraging with workers of Aphaenogaster, but potential benefits for Camponotus have not been studied.

Association with Other Organisms

All Associate Records for Genus

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Taxon Relationship Associate Type Associate Taxon Associate Relationship Locality Source Notes
Aphaenogaster baronii host fungus Aegeritella maroccana pathogen Espadaler & Santamaria, 2012
Aphaenogaster fulva host ant Aphaenogaster tennesseensis temporary parasite
Aphaenogaster fulva prey syrphid fly Omegasyrphus coarctatus predator Quevillon, 2018
Aphaenogaster gibbosa mutualist butterfly Lampides boeticus Obregon et al. 2015
Aphaenogaster kurdica mutualist aphid Brachycaudus helichrysi trophobiont Mortazavi et al., 2015; Saddiqui et al., 2019
Aphaenogaster picea host ant Aphaenogaster tennesseensis temporary parasite
Aphaenogaster relicta associate (details unknown) bethylid wasp Pseudisobrachium terresi associate (details unknown) Quevillon, 2018
Aphaenogaster rudis host ant Aphaenogaster tennesseensis temporary parasite
Aphaenogaster senilis host fungus Myrmicinosporidium durum pathogen Portugal Gonçalves et al., 2012.
Aphaenogaster subterranea host nematode Mermithidae (unspecified "Mermix") parasite Germany (Wuerzburg) Gösswald, 1938; Laciny, 2021
Aphaenogaster subterranea xenobiont ant Camponotus ligniperda xenobiont Hungary Kanizsai et al., 2013 Pine forest. Under stone.
Aphaenogaster tennesseensis temporary parasite ant Aphaenogaster fulva host
Aphaenogaster tennesseensis temporary parasite ant Aphaenogaster picea host
Aphaenogaster tennesseensis temporary parasite ant Aphaenogaster rudis host
Aphaenogaster texana host phorid fly Apocephalus portalensis parasite phorid.net attacked
Aphaenogaster treatae host cricket Myrmecophilus pergandei myrmecophile United States

Flight Period

All Flight Records for Genus

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Taxon Month Source Notes
Aphaenogaster fulva Aug Sep Oct antkeeping.info
Aphaenogaster lamellidens May Jun antkeeping.info
Aphaenogaster occidentalis Jun Jul Aug Sep antkeeping.info
Aphaenogaster picea May antkeeping.info
Aphaenogaster rudis Jul Aug antkeeping.info
Aphaenogaster subterranea Jul Aug Sep antkeeping.info
Aphaenogaster tennesseensis Jun antkeeping.info
Aphaenogaster texana Jun antkeeping.info

Life History Traits

  • Mean colony size: 100-303 (Greer et al., 2021)
  • Compound colony type: not parasitic (Greer et al., 2021)
  • Nest site: hypogaeic (Greer et al., 2021)
  • Diet class: omnivore (Greer et al., 2021)
  • Foraging stratum: subterranean/leaf litter (Greer et al., 2021)
  • Foraging behaviour: solitary; cooperative (Greer et al., 2021)

Castes

Morphology

Worker Morphology

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• Antennal segment count: 12 • Antennal club: absent, gradual, 4 weak • Palp formula: 5,3; 4,3 • Total dental count: 7-16 (-6) • Spur formula: 1 simple, 1 simple; 0, 0 • Eyes: >100 ommatidia • Scrobes: absent • Pronotal Spines: absent • Mesonotal Spines: absent • Propodeal Spines: dentiform; present • Petiolar Spines: absent • Caste: most monomorphic, at least one species polymorphic • Sting: present • Metaplural Gland: present • Cocoon: absent


Karyotype

Species Uncertain

  • 2n = 30 (Malaysia) (Goni et al., 1982).

All Karyotype Records for Genus

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Taxon Haploid Diploid Karyotype Locality Source Notes
Aphaenogaster 30 Malaysia Goni et al., 1982
Aphaenogaster beccarii 30 46 India; Malaysia Imai et al., 1983; Imai et al., 1984
Aphaenogaster depilis 34 Tunisia Hauschteck-Jungen & Jungen, 1983
Aphaenogaster famelica 17 34 Japan Imai & Yosida, 1964; Imai, 1966; Imai, 1969; Imai, 1971
Aphaenogaster fulva 36 USA Crozier, 1977
Aphaenogaster gibbosa 11 16 17 34 4M+2SM+4ST+6T; 6M+4SM+8ST+16T Switzerland Hauschteck-Jungen & Jungen, 1983; Lorite et al., 2000; Palomeque et al., 1993b this karyotype is reported as fusion of two telocentric chromosomes
Aphaenogaster iberica 17 34 6M+4SM+8ST+16T Spain Palomeque et al., 1993a; Palomeque et al., 1993b; Lorite et al., 2000 ocurrence of supernumery chromosome segment
Aphaenogaster japonica 22 Japan Imai, 1969
Aphaenogaster lamellidens 38 USA Crozier, 1977; Taber & Cokendolpher, 1988
Aphaenogaster longiceps 45 46 Australia Imai et al., 1977 a metacentric pair is single and two telocentric corresponds the arms
Aphaenogaster miamiana 36 USA Crozier, 1977
Aphaenogaster osimenseis 16 32 Japan Imai & Yosida, 1964; Imai & Yosida, 1966; Imai, 1966; Imai, 1969; Imai, 1971
Aphaenogaster rudis 18 20 40 41 42 44 USA Crozier, 1977 suggested to be due supernumerary chromosome
Aphaenogaster sardoa 34 Tunisia Hauschteck-Jungen & Jungen, 1983
Aphaenogaster senilis 16 32 6M+6SM+20ST Spain Palomeque et al., 1993a; Palomeque et al., 1993b; Lorite et al., 2000
Aphaenogaster smythiesii 11 22 34 20SM+2M; 16M+18A India; Japan Imai, 1969; Imai, 1971; Imai et al., 1984
Aphaenogaster subterranea 11 22 Germany; Switzerland Hauschteck, 1962; Hauschteck-Jungen & Jungen, 1983
Aphaenogaster testaceopilosa 17 34 Croatia; Spain; Tunisia Hauschteck-Jungen & Jungen, 1983 Lorite and Palomeque 2010 states some issues about the identification/sampling location
Aphaenogaster tipuna 34 Taiwan Hung et al., 1972
Aphaenogaster treatae 42 USA Crozier, 1977

Phylogeny

Myrmicinae
Myrmicini
Pogonomyrmecini
Stenammini
Solenopsidini
Attini

Ochetomyrmex  (2 species, 0 fossil species)

Tranopelta  (2 species, 0 fossil species)

Diaphoromyrma  (1 species, 0 fossil species)

Lachnomyrmex  (16 species, 0 fossil species)

Blepharidatta  (4 species, 0 fossil species)

Allomerus  (8 species, 0 fossil species)

Wasmannia  (11 species, 0 fossil species)

Pheidole  (1,294 species, 7 fossil species)

Cephalotes  (123 species, 16 fossil species)

Procryptocerus  (44 species, 0 fossil species)

Strumigenys  (880 species, 4 fossil species)

Phalacromyrmex  (1 species, 0 fossil species)

Pilotrochus  (1 species, 0 fossil species)

Protalaridris  (7 species, 0 fossil species)

Rhopalothrix  (19 species, 0 fossil species)

Basiceros  (9 species, 0 fossil species)

Octostruma  (35 species, 0 fossil species)

Eurhopalothrix  (55 species, 0 fossil species)

Talaridris  (1 species, 0 fossil species)

Acanthognathus  (7 species, 1 fossil species)

Daceton  (2 species, 0 fossil species)

Lenomyrmex  (7 species, 0 fossil species)

Microdaceton  (4 species, 0 fossil species)

Orectognathus  (29 species, 0 fossil species)

Colobostruma  (16 species, 0 fossil species)

Epopostruma  (20 species, 0 fossil species)

Mesostruma  (9 species, 0 fossil species)

Paleoattina

Apterostigma  (44 species, 2 fossil species)

Mycocepurus  (6 species, 0 fossil species)

Myrmicocrypta  (31 species, 0 fossil species)

Neoattina

Cyatta  (1 species, 0 fossil species)

Kalathomyrmex  (1 species, 0 fossil species)

Mycetarotes  (4 species, 0 fossil species)

Mycetosoritis  (2 species, 0 fossil species)

some Cyphomyrmex  (23 species, 2 fossil species)

some Cyphomyrmex

Paramycetophylax  (1 species, 0 fossil species)

Mycetophylax  (21 species, 0 fossil species)

Mycetagroicus  (4 species, 0 fossil species)

Mycetomoellerius  (31 species, 1 fossil species)

Sericomyrmex  (11 species, 0 fossil species)

Xerolitor  (1 species, 0 fossil species)

Paratrachymyrmex  (9 species, 0 fossil species)

Trachymyrmex  (9 species, 0 fossil species)

Amoimyrmex  (3 species, 0 fossil species)

Atta  (20 species, 1 fossil species)

some Acromyrmex  (56 species, 0 fossil species)

some Acromyrmex

Pseudoatta  (2 species, 0 fossil species)

Crematogastrini

Rostromyrmex  (1 species, 6 fossil species)

Cardiocondyla  (89 species, 0 fossil species)

Ocymyrmex  (34 species, 0 fossil species)

Nesomyrmex  (84 species, 2 fossil species)

Xenomyrmex  (5 species, 0 fossil species)

Terataner  (14 species, 0 fossil species)

Atopomyrmex  (3 species, 0 fossil species)

Cataulacus  (65 species, 3 fossil species)

Carebara  (249 species, 9 fossil species)

Diplomorium  (1 species, 0 fossil species)

Melissotarsus  (4 species, 1 fossil species)

Rhopalomastix  (14 species, 0 fossil species)

Calyptomyrmex  (38 species, 0 fossil species)

Strongylognathus  (27 species, 0 fossil species), Tetramorium  (601 species, 2 fossil species)

Cyphoidris  (4 species, 0 fossil species)

Dicroaspis  (2 species, 0 fossil species)

Aretidris  (2 species, 0 fossil species)

Vollenhovia  (83 species, 3 fossil species)

Dacetinops  (7 species, 0 fossil species)

Indomyrma  (2 species, 0 fossil species)

Crematogaster  (784 species, 3 fossil species)

Meranoplus  (91 species, 0 fossil species)

Lophomyrmex  (13 species, 0 fossil species)

Adlerzia  (1 species, 0 fossil species)

Recurvidris  (12 species, 0 fossil species)

Stereomyrmex  (3 species, 0 fossil species)

Trichomyrmex  (29 species, 0 fossil species)

Eutetramorium  (3 species, 0 fossil species)

Royidris  (15 species, 0 fossil species)

Malagidris  (6 species, 0 fossil species)

Vitsika  (16 species, 0 fossil species)

Huberia  (2 species, 0 fossil species)

Podomyrma  (62 species, 1 fossil species)

Liomyrmex  (1 species, 0 fossil species)

Metapone  (31 species, 0 fossil species)

Kartidris  (6 species, 0 fossil species)

Mayriella  (9 species, 0 fossil species)

Tetheamyrma  (2 species, 0 fossil species)

Dacatria  (1 species, 0 fossil species)

Proatta  (1 species, 0 fossil species)

Dilobocondyla  (22 species, 0 fossil species)

Secostruma  (1 species, 0 fossil species)

Acanthomyrmex  (19 species, 0 fossil species)

Myrmecina  (106 species, 0 fossil species)

Perissomyrmex  (6 species, 0 fossil species)

Pristomyrmex  (61 species, 3 fossil species)

some Lordomyrma  (36 species, 0 fossil species)

Propodilobus  (1 species, 0 fossil species)

Lasiomyrma  (4 species, 0 fossil species)

some Lordomyrma

Ancyridris  (2 species, 0 fossil species)

some Lordomyrma

Paratopula  (12 species, 0 fossil species)

Poecilomyrma  (2 species, 0 fossil species)

Romblonella  (10 species, 0 fossil species)

Rotastruma  (3 species, 0 fossil species)

Gauromyrmex  (3 species, 0 fossil species)

Vombisidris  (19 species, 0 fossil species)

Temnothorax  (512 species, 7 fossil species)

Harpagoxenus  (4 species, 0 fossil species)

Formicoxenus  (8 species, 0 fossil species)

Leptothorax  (20 species, 0 fossil species)

See Phylogeny of Myrmicinae for details.

Fossil History

This section modified from Radchenko et al. (2024).

More than 20 fossil species were assigned to Aphaenogaster till recently, but Radchenko & Perkovsky (2016) transferred many of them to the morphotaxon Paraphaenogaster. As a result, we now assign to the genus Aphaenogaster 14 extinct species described from these regions:

  • North America: Florissant, Colorado, United States (Late Eocene), Quesnel, British Columbia, Canada (Early Miocene?)
  • Mexico: Mexican amber, Chiapas, Mexico (Middle Miocene)
  • Dominican Republic: Dominican amber, Dominican Republic (Burdigalian, Early Miocene)
  • Europe: Baltic amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene), Bitterfeld amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene), Enspel Formation, Rhineland-Palatinate, Germany (Oligocene), Rott, Westphalia, Germany (Late Oligocene), Rovno amber, Baltic Sea region, Europe (Priabonian, Late Eocene), Sakhalin amber, Ukraine (Thanetian, Paleocene)
  • China: Zhangpu amber, Zhangpu County, Fujian Province, China (Miocene), an undescribed species

These date from the middle Eocene (47–43 Ma) to the middle Miocene (26–15 Ma) (Radchenko & Perkovsky, 2016; Jessen, 2020). Four of the species were described from the Late Eocene European ambers (Priabonian age, 37.8–33.9 Ma), particularly: Aphaenogaster sommerfeldti, Aphaenogaster mersa, Aphaenogaster oligocenica and Aphaenogaster antiqua. Recently Radchenko et al. (2024) found two Aphaenogaster species from two pieces of Baltic amber, Aphaenogaster groehni and Aphaenogaster ribbeckei.

The origin of the Stenammini crown-group, to which Aphaenogaster belongs, is assumed to be around 51 Ma (Early Eocene), and the Aphaenogaster clade is inferred to have originated in the Palaearctic 42.2 Ma (Middle Eocene) (Ward et al., 2015; Branstetter et al., 2022). The latter dating is quite consistent with paleontological data, although the time of origin of Aphaenogaster should be early rather than middle Eocene. The fact is that the oldest known fossil, Aphaenogaster dlusskyana, has been found in Middle Eocene Sakhalin amber. It was already a “typical” Aphaenogaster with a slender body, a moderately elongated suboval head, a rather long scape, and palp formula 5, 3 (for details see Radchenko & Perkovsky, 2016). Thus, it can be assumed that Aphaenogaster arose before the middle Eocene.

While as currently conceived Aphaenogaster is paraphyletic, it is likely that “true” Aphaenogaster evolved in the Eocene warm forests and led an epigean lifestyle. Further morphological radiation began much later and was associated with adaptation to the drier and open habitats in Miocene (Branstetter et al., 2022; Schifani et al., 2022). The main evolutionary-morphological trend can be the elongation of the head, body, legs and antenna, so that the head could become elongated-oval, strongly narrowed backward and without occipital corners. In this case Eocene-Oligocene fossil species do not appear to be specialised. These are species from the Late Eocene European ambers, as well as Aphaenogaster donisthorpei and Aphaenogaster mayri (Florissant, United States, terminal Eocene), Aphaenogaster archaica (Rott, Germany, Late Oligocene) and Aphaenogaster enspelensis (Enspel Formation, Germany, Late Oligocene). At the same time, Miocene species from the Dominican and Mexican ambers were already quite specialised. For example, Aphaenogaster amphioceanica has a very elongated and narrowed posteriorly head with a “neck” (as in species of the former subgenus Deromyrma), and Aphaenogaster praerelicta has very long propodeal spines and a pair of short spines on the humeral angles (for more details see De Andrade, 1995).

However, all previously known Aphaenogaster species from the Late Eocene European ambers (Mayr, 1868; Wheeler, 1915; Dlussky & Perkovsky, 2002) are unspecialised: they have not very elongated head, mesosoma and appendages, a head with rounded, but clearly defined occipital corners, while all of these species well distinguished from each other and can be assigned to different species groups. On the other hand, the Baltic amber species Aphaenogaster groehni and Aphaenogaster ribbeckei have some specialised features. Thus, mesosoma in A. ribbeckei is more slender (ML/MH 3.7 vs. < 3.0 in other species) and head in A. groehni is narrowed posteriorly and without marked occipital corners, and scape is distinctly longer than in all other amber species.

All these indicate that in the Late Eocene Aphaenogaster had undergone considerable diversification, ranking third in the number of species among the amber Myrmicinae genera, second only to Temnothorax (with 7 species) and Myrmica (with 18 species) (Radchenko, 2023; Radchenko, unpubl.).

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • APHAENOGASTER [Myrmicinae: Stenammini]
    • Aphaenogaster Mayr, 1853b: 107. Type-species: Aphaenogaster sardoa, by subsequent designation of Bingham, 1903: 270.
    • Aphaenogaster junior synonym of Atta: Mayr, 1863: 395.
    • Aphaenogaster subgenus of Stenamma: Emery, 1895c: 298.
    • Aphaenogaster revived status as genus: Emery, 1908c: 309.
    • Aphaenogaster senior synonym of Novomessor: Brown, 1974b: 47.
    • Aphaenogaster senior synonym of Attomyrma, Deromyrma, Novomessor, Nystalomyrma, Planimyrma: Smith, D.R. 1979: 1359; Bolton, 1982: 364.
    • Aphaenogaster senior synonym of Brunella: Bolton, 1982: 364.
    • Aphaenogaster senior synonym of †Sinaphaenogaster: Bolton, 2003: 230, 273.
  • ATTOMYRMA [junior synonym of Aphaenogaster]
    • Attomyrma Emery, 1915d: 70 [as subgenus of Aphaenogaster]. Type-species: Formica subterranea, by original designation.
    • Attomyrma junior synonym of Aphaenogaster: Bolton, 1982: 364.
  • BRUNELLA [junior synonym of Aphaenogaster]
    • Brunella Forel, 1917: 234. Type-species: Aphaenogaster belti, by monotypy.
    • Brunella junior synonym of Atopula: Emery, 1924d: 242; Donisthorpe, 1943f: 629.
    • Brunella junior synonym of Aphaenogaster: Bolton, 1982: 364; Bolton, 1994: 106.
  • DEROMYRMA [junior synonym of Aphaenogaster]
    • Deromyrma Forel, 1913b: 350 [as subgenus of Aphaenogaster]. Type-species: Aphaenogaster (Ischnomyrmex) swammerdami, by original designation.
    • [Deromyrma also described as new by Forel, 1913k: 49.]
    • Deromyrma junior synonym of Aphaenogaster: Bolton, 1982: 364.
  • NYSTALOMYRMA [junior synonym of Aphaenogaster]
    • Nystalomyrma Wheeler, W.M. 1916j: 215 [as subgenus of Aphaenogaster]. Type-species: Myrmica longiceps, by original designation.
    • Nystalomyrma junior synonym of Aphaenogaster: Bolton, 1982: 364.
  • PLANIMYRMA [junior synonym of Aphaenogaster]
    • Planimyrma Viehmeyer, 1914d: 604 [as subgenus of Aphaenogaster]. Type-species: Stenamma (Ischnomyrmex) loriai, by original designation.
    • Planimyrma junior synonym of Aphaenogaster: Bolton, 1982: 364.
  • †SINAPHAENOGASTER [junior synonym of Aphaenogaster]
    • Sinaphaenogaster Zhang, J. 1989: 266 [as subgenus of Aphaenogaster]. Type-species: †Paraphaenogaster shanwangensis, by original designation.
    • Sinaphaenogaster junior synonym of Aphaenogaster: Bolton, 2003: 230, 273.


Unpublished evidence has suggested Aphaenogaster is not monophyletic. A molecular phylogenetic study is needed to resolve this problem.

References