The Ants of India

This page is meant to serve as an introduction to India's ants. Links to a range of resources are also organized here. Bharti et al. (2016) provide the most comprehensive overview of the Indian ant fauna. Much of the information given below is from or is based on this landmark study.

India - Importance and Context
The Indian subcontinent is well known for its high biodiversity, varied environments and habitats, and interesting geological history. However, much work remains to document and catalogue the species of India and their geographic distributions, especially for diverse invertebrate groups. The country, with a total land area of over 3.2 million km2, is positioned on the Indian Plate (the northern portion of Indo-Australian plate) which separated from Gondwanaland during the late Cretaceous, then collided with Eurasia in the Cenozoic (Briggs 2003, Lomolino et al. 2010), although the precise age of this event is still debated (Aitchison et al. 2007). The collision led to the formation of Tibetan Plateau and the Himalaya. The Indian Plate has acted as a vessel carrying fauna and flora from Africa and Madagascar to Eurasia (Briggs 2003). This varied geological history has led to the emergence of a wide diversity of flora and fauna in India, which comprises Malayan, Afrotropical, Mediterranean, central Asian and eastern Palearctic elements.

Most of the country’s land can be assigned to one of two ecozones, the Palaearctic and Indo-Malayan, and 13 terrestrial ecoregions (Olson et al. 2001). The Himalayan system, part of the Palaearctic ecozone, stretches over 3000 kilometers in length, from Myanmar to east of Afghanistan (between longitudes 70E to 100E and latitudes 25N to 40N) and from 80 kilometers to 300 kilometers in width (Bharti 2008). The Himalayas, which form the northern boundary of the country, span across ten states (Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, Meghalaya, Tripura, Manipur, Mizoram, Nagaland, Arunachal Pradesh and a little part of Assam and West Bengal). The mountain system extends from east of Brahmaputra to the bend of Indus in the west, but the Himalayan system stretches further from Myanmar to Afghanistan. Kunlun represents the northern extreme of the Himalayan range, followed by the Tibetan plateau. The mountain system meets with high ranges of Central Asia (Hindu Kush, Trans Karakoram, Tian Shan, Kunlun, Trans Alai) forming the Pamir Knot, and Tibet lies to the north-east. The Western Ghats are part of the Western Ghats-Sri Lanka global hotspot, running roughly in a North-south direction for about 1500 kilometres parallel to the coast bordering the Arabian Sea.

Approximately 21% of the country’s landmass is covered by forests (tree canopy density >10%), of which 12% comprises moderately or very dense forests (tree canopy density >40%) (CBD 2014). These include tropical rainforests of the Andaman Islands, the Western Ghats, and Northeast India; coniferous forests of Himalaya; deciduous Sal (Shorea robusta) forest of Eastern India; the dry deciduous Teak (various species of Tectona) forest of Central and Southern India; and the Babul (Acacia) dominated thorn forest of the Central Deccan and Western Gangetic plain (Tritsch 2001). According to the latest estimates (CBD 2014), the country accounts for 7–8% of the total plant and animal species globally recorded, including over 45,000 species of plants and 92,873 species of animals. This included 423 mammalian species (7.81% of Indian total), 1,233 avian species (13.66%), 526 reptilian species (5.7%), 342 amphibian species (5.05%), 3,022 fish species (9.41%) and 63,423 of insects species (6.22%). Out of these, about 4,045 species of flowering plant (angiosperms), 47 species of mammals, 53 species of birds, 156 species of reptiles and 168 species of amphibians are endemic to India (CBD 2014). Most of the endemic taxa listed above are localised in one of the four biodiversity hotspots recognised in India; Himalaya, Indo-Burma, the Western Ghats - Sri Lanka and Sundaland (Nicobar Islands) (Myers et al. 2000 and CBD 2014).

Historical Ant Faunal Studies
Jerdon (1851, 1854) catalogued the ants of Southern India. Later, Forel (1900a,b, 1901) extended the list by adding 267 new species from the region. Comprehensive documentation of Indian ants was carried by Bingham (1903), who included all the previous works. Later, further contributions were made by various myrmecologists including Forel, Donisthorpe, Emery, Santschi, Mukerjee, Brown, Bolton in terms of descriptions of new taxa (Appendix 1). However, the first ever checklist which cited Indian ants was published by Chapman and Capco (1951; Appendix 1) in their revision of Asian ants. Later efforts to combine knowledge on Indian ants were performed by Guénard and collaborators (Guénard et al. 2010; 2012) in the context of global generic richness and distribution in Asia. In recent years, Bharti and co-workers significantly increased our understanding of ant diversity with both new species descriptions and new distributional records (Appendix 1). This led Bharti (2011) to compile the first modern species checklist inclusive of all earlier records for 652 valid species and subspecies from India and include all the ant records from Himalaya irrespective of its political division. Despite all these efforts, our knowledge about the diversity and distribution of Indian ants remains incomplete and fragmentary, especially on finer geographic scales.

This present study provides a comprehensive and critical list of Indian ants with current known state-wise distribution. The intent is to consolidate previous data, to identify potential erroneous data, misidentifications, dubious distributional records, and more generally to provide a holistic view about the diversity and distribution of Indian ants. This list should also help identify major undersampled areas where future sampling and taxonomic efforts should be directed.

Ant Diversity

 * List of Indian ant genera
 * List of Indian ant species

Overview
As of 2016, 828 species and subspecies are known from India. These ants representing 100 genera grouped in 10 subfamilies. In terms of species richness, the subfamily Myrmicinae is the most speciose (354 species, 42.7%), followed by Formicinae (241 species, 29.1%) Ponerinae (111 species, 13.4%), Dorylinae (55 species, 6.6%) and Doli- choderinae (30 species, 3.6%), while the rest of the smaller subfamilies together constitute 4.2% (Pseudomyrmecinae 11 species, Amblyoponinae 10 species, Proceratiinae State wise distribution of Indian ants 56 species, Ectatomminae 5 species and Leptanillinae 4 species). The trend for generic richness is almost the same except for the subfamily Ponerinae which represents a larger percentage of generic richness than Formicinae (Myrmicinae 37.4%, Ponerinae 20.2% and Formicinae 18.2%).

Generic Species Richness
The most speciose ant genus is Camponotus with 83 named species (one tenth of the total known Indian species), followed by Polyrhachis (71 species, 8.5%), Pheidole (58 species, 7.0%). Other diverse genera include Tetramorium and Crematogaster (42 and 41 species, each 5.0%), Leptogenys (34 species, 4.1%), Myrmica (33 species, 4.0%), Aenictus (32 species, 3.8%), Strumigenys and Carebara (24 species each, 2.9%) respectively (Table 1). Above and beyond these ten genera which have wide distribution within India (except Myrmica, which is restricted to Himalayan region), a large majority of genera (66) can be at this point perceived as species-poor in India (5 or less species) including 30 monospecific genera in India (Table 1), and inclusive of two monotypic exotic genera Anoplolepis and Paratrechina.

Within India, several genera including Myrmica, Formica, Lasius, Stenamma, Perissomyrmex and a majority of the species of Aphaenogaster and Temnothorax are re- stricted to the Palearctic region of Himalaya (Table 2, Bharti 2008), while the genera Calyptomyrmex, Emeryopone, Indomyrma, Lordomyrma, Myrmoteras, Tyrannomyrmex and Yavnella represent tropical elements restricted to Western Ghats, and Metapone to Nicobar Islands. Other tropical genera (Anillomyrma, Buniapone, Centromyrmex, Dilo- bocondyla, Discothyrea, Gauromyrmex, Gesomyrmex, Indomyrma, Kartidris, Liomyrmex, Mayriella, Myopopone, Odontoponera, Oecophylla, Paraparatrechina, Paratopula, Plat- ythyrea, Probolomyrmex, Rhopalomastix, Tyrannomyrmex, Vollenhovia and Vombisidris) are represented by one or few species (Table 2).

Despite including nearly a third of the global ant generic richness (100/323), no genera are known to be endemic to India.

Regional Diversity
Two biogeographically significant regions of India, Himalaya and Western Ghats harbour a large number of ant species. 656 species from 88 genera were recorded from Himalaya, and 455 species from 75 genera were recorded from the Western Ghats. From a total 828 species, 256 species (31%) we considered endemic to India and approximately 71% of these endemics are exclusively concentrated in two of the above listed biodiversity hotspots. Although we feel that some of the Indian states are underrepresented in the existing data due to inadequacy of surveys, based on the currently available data the state of West Bengal has the highest number of species (382) representing 65 genera followed by state of Sikkim with 276 species representing 69 genera.

Endemism
The endemism of Indian ants (31%) is much higher than for birds (4.3%), fishes (8%), angiosperms (10%) or mammals (11%), lower than amphibians (49%) and most similar to reptiles (29%) (CBD 2014). With nearly one of three ant species known to be endemic to India, more conservation efforts should be directed to this group to evaluate the distribution and ecology of these species and evaluate the potential threat that some of these species might already experience.

Exotic Species
Among the species present in India, 24 species are considered here as non-native (see Table 3), although the exact origin of a few other species is still uncertain and thus could be included (or removed) if more targeted future studies are conducted. Among the exotic species, several are known for their invasive ecological characteristics: Anoplolepis gracilipes, Paratrechina longicornis, and Pheidole megacephala. The ecological impacts of these species in India have not been studied to date. Furthermore, this list could, and likely will, expand in the future with new arrivals. In particular, several damaging species including Solenopsis invicta and Wasmannia auropunctata are already widespread in tropical and subtropical parts of Asia and with no doubt could find suitable habitats within the diversity of Indian ecosystems if given the opportunity. Both prevention and control measures would be highly advisable to protect Indian ecosystems and economic interests from the arrival of invasive species.

India Identification Keys
Key to Anochetus of India

Key to Carebara of India

Key to Cerapachys of India

Key to Cryptopone of India

Key to Aenictus of India

Key to the Lasius of the Indian Himalayas

Key to Leptogenys of India

Key to Meranoplus of India

Key to Nylanderia of India

Key to Pseudolasius of India

Key to Strumigenys of India

Key to Tetramorium of India

Key to Tetraponera of India

Cerapachys
Bharti H, Ali Akbar S. 2013b. Taxonomic studies on the ant genus Cerapachys Smith (Hymenoptera, Formicidae) from India. ZooKeys 336: 79–103. doi: 10.3897/zookeys.336.5719 [[Media:Bharti & Akbar 2013.pdf|PDF]]

Twelve species are present and for convenience can be placed into arbitrary groups. Group I species with 12 segmented antennae viz., C. sulcinodis, C. anokha, C. schoedli, C. seema, C. indicus, C. aitkenii, C. wighti, C. longitarsus and C. nayana. Of the 9 species given above the first four i.e., C. sulcinodis, C. anokha, C. schoedli and C. seema, have the punctures on the dorsum of the head relatively small, separated, with their diameter smaller than the average distance separating them. Among these C. anokha, with the declivous face of the propodeum lacking cariniform margins, and C. sulcinodis, with the dorsal surface of the petiolar node with a smooth, median area are distinct species in the group. C. schoedli and C. seema are easily separated. C. seema has dull body colouration, sculpture much more prominent and coarse, pilosity denser and head almost oval, with the anterior and posterior sections of its sides converging, while C. schoedli is brightly coloured, with sculpture and pilosity reduced and the head rectangular with parallel sides. The next 3 species i.e., C. indicus, C. aitkenii and C. wighti, have the punctures on the dorsum of the head large, their diameter greater than the average distance separating them. Among these C. wighti has the smallest size (HW 0.59 mm) and relatively reduced eyes (EL 0.05 mm) whereas C. aitkenii and C. indicus are easily separated from each other on the basis of body sculpture and colouration. C. aitkenii has characteristic bicolouration and its body sculpture is foveate, whereas C. indicus is mostly piceous with bluish iridescent sheen and reduced sculpture. The remaining 2 species i.e., C. longitarsus and C. nayana are members of ‘Phyracaces lineage’ and easily recognized, with strong overhanging dorsolateral margins to the petiole. The two species are separated from each other on the basis of body colouration. C. longitarsus has characteristic bicolouration with head brown, trunk red or brown, petiole and postpetiole light to dark reddish and gaster brown or black, while C. nayana is uniformly black in colour, with mandibles, antennae and legs castaneous. Group II species have antennae with less than 12 segments viz., C. biroi, C. alii and C. besucheti. Among these C. besucheti has 11 segmented antennae while C. biroi and C. alii have 9 segmented antennae. C. biroi is characterized by its opaque body with closely spaced piligerous punctures, while C. alii has prominent foveate body sculpture.

Workers grade into a number of “atypical” reproductives. These morphologically “atypical” ant reproductives have been assigned a number of descriptive terms. However Peeters (2012) advocate use of “ergatoid queens” for all wingless reproductives that differ morphologically from workers. These ergatoid queens are formed as a response to selective pressures against long range dispersal and solitary colony foundation (Peeters and Molet 2010). Ergatoid queens have been reported previously in Cerapachys (Brown, 1975). Here we present ergatoid queens of three more species — C. nayana, C. schoedli and C. seema. In evaluating morphometric data of the three castes of C. seema i.e. worker, ergatoid queens and queen castes (Fig. 41) it is observed that ergatoid queens are closer to gynes than the workers. Further inference and analysis on the subject is beyond the scope of this paper and would require much more information. However