Notes on genera and species of Ponerinae

Under this subfamily, 13 species belonging to 6 genera were identified. Most of the members belonging to this subfamily nests in soil or in deaying vegetation. They are strictly monomorphic. In many genera a well differentiated quen caste is lost, instead a mated worker functions as queen.

Genus 1. Anochetus Mayr

Members of the genus Anochetus form small nests in soil or under logs. They commonly forage in leaf litter and are very rarely seen. They forage individually.  They can be readily identified by the special nature of the head and by the long trap like mandibles. The mandibles are long and straight with 2/3 large teeth near the tip and are inserted in the middle of the front margin of the head. In our Campus there are 4 species belonging to this Genus.

Key to species of the genus Anochetus

1.  Length under 5mm 2
Length over 5mm 3
2. Length 4mm,head and thorax reddish brown, abdomen darker, node of pedicel rounded above graeffei Mayr
Length 4.5mm, head, thorax and abdomen reddish brown, petiolar node bilobed Anochetus sp.5
3.  Length 6mm, head striate, head and thorax reddish brown, petiolar node and abdomen black obscurior Brown 
Length 6.5 mm, head smooth, thorax, node and first abdominal segment reddish brown yerburyi Forel
1.1. Anochetus graeffei Mayr

Anochetus graeffei Mayr, 1870. Verh. Zool.- Bot. Ges. Wien, 20 : 939 – 996.

Members of this species are monomorphic, have an average length of 3.5-4mm. It’s colour is dark brown. Head, thorax and abdomen have dense pilosity and pubescence. 

Where do we find the nests?

It is known to make shallow nests in soil. This is not a very common species in our Campus.

 Range: India, Burma and Sri Lanka (Bingham, 1903).

1.2 Anochetus obscurior Brown

Anochetus obscurior Brown, 1978.  Stud. Entomol. (N.S.) 20 : 549 – 652.

The nesting habits of this species are not known. This species is larger in size than A. graffei. Head and thorax reddish brown, node and abdomen are black. Head striate, thorax, node and the first abdominal segments are punctured. This is a widespread species and is reported from South India by Brown (1978).

1.3  Anochetus yerburyi  Forel

Anochetus yerburyi  Forel, 1900.  J. Bombay Nat. Hist. Soc., 13: 52 – 65.

So far this is known only from Sri Lanka. Head and abdomen are smooth. Thorax is sculptured. Nesting habits are not known.

Range: India and Sri Lanka (Brown, 1978, Varghese, 2003).

1.4   Anochetus  sp. 5 (Museum number)

Length 4.5mm. This species differs from all others in having a bilobed petiolar node. Head, thorax and abdomen are punctured and reddish brown in colour. This species is smaller than A. yerburyi and A. obscurior and its nesting habits are not known. 

Genus 2. Diacamma Mayr

On this campus, there are 2 species under this genus. They can be easily identified by a combination of characters, ie., size, colour, external morphology, majestic walk and by their characteristic nests. This is a monomorphic species.

2.1.  Diacamma ceylonense Emery

Diacamma ceylonense Emery, 1897. Rend. Sess. R. Acad. Sci. Ist. Bologna, 1 : 147 – 167.

Members of this species have an average length of 11.59 mm. It is greyish black and shiny in appearance (pale look is attributed to the thick small hairs all over the body). Mandibles, tips of legs and abdomen are dark reddish brown. Head, thorax, petiole and the first two gastral tergites are deeply striated. Entire body is covered with dense pubescence and sparse erect hairs. This is a monomorphic species. Males are reddish brown in colour.

Where do we find the nests of Diacamma ceylonense?

Members of this species inhabit open fields with or without grass. It builds nests usually with characteristic mound, with a small, single entrance (very rarely two entrances). Mound height ranges from 0-10 cm. The depth of the nest ranges from 40-180 cm. Immediate vicinity of the nest entrance and a portion of the mound is always decorated with an admixture of dried leaves, slender dry twigs, bird feathers, dead ants (mainly Leptogenys sp.), caterpillar skins, spider exuviae etc. This kind of nest is characteristic of Diacamma ceylonense. Colonies are seen aggregated in the Jubilee garden and scattered in other parts of the Indian Institute of Science Campus, Bangalore. A single nest can contain as many as 600 individuals. It forages individually, no recruitment or trail formation occurs during foraging or nest shifting. During nest shifts a special behaviour called  “Tandem running” is seen, in which usually one individual follows another to a new nesting site.

2.2. Diacamma indicum

This species is recently added to the list of ant fauna of IISc, so it is not at present included in the key. This is slightly smaller in size than D.ceylonense. It make nest in soil and in crevices of walls, holes on trees etc., but it doesn't have the elaborate nest entrance structure as one see in other species.

Genus 3. Harpegnathos Jerdon

We have only one species under this genus.  Members of this species have characteristically long and linear mandibles. This is known for its jumping nature. 

3.1. Harpegnathos saltator (Jerdon)

Drepanognathus saltator Jerdon, 1851, Madras J. Lit. Sci., 17: 116.

Length 15mm. Head, thorax and node are reddish and abdomen is black. In this species, mandibles are unusually long and slightly curved upwards. This species nests in soil, with a low mound decorated with twigs and leaves, with a very small nest entrance. I have seen its nests in Acacia plantations, where there are lots of Diacamma nests. Nest entrance is always characteris-tically decorated. It closes its nest in the evening and opens late in the morning. I have observed that on some days it will remain closed!!!!! This is a monomorphic species and forage individually.

Distribution: Karnataka (Ali, 1991), (Bangalore, Mysore, Shimoga, Virajpet, Gunddahalli, Dharwad), Western India and Kerala (Bingham, 1903), (I have observed this species in Wynad district of Kerala state also). 

Range: India, China and Sri Lanka (Bingham, 1903: Chapman & Capco, 1951; Ali, 1991 and Tiwari, 1999)

Genus 4. Leptogenys Roger

Leptogenys is a large genus. The body is long and slender. They make nest in loose soil on ground. Members of this group have the habit of changing their nesting sites quite frequently. Some species forage singly while others forage in distinct trails. We have 2 species under this genus. The most important identification character for this genus is the pectinate nature of the tarsal claws (claws have a series of small teeth on their inner surface).

Key to species

1. Dark castaneous brown, head, thorax and abdomen covered with fairly abundant long pilosity, moves in trails processionalis (Jerdon)
Black, body with sparse pilosity, no trail formation chinensis (Mayr)

4.1. Leptogenys chinensis (Mayr)

Lobopelta chinensis Mayr, 1870, Verh. Zool. – Bot. Ges. Wien. 20: 965.

Bingham (1903) mentions that this species is distributed more or less throughout Continental India and Ceylon, except the drier portions of Central and Western India and Punjab. This species is black, smooth and shining. Body is more or less elongate and slender, nests in soil, and is very common in Bangalore.

Range: India, Sri Lanka, China and Japan (Bingham, 1903) and Philippines (Chapman & Capco, 1951).

4.2. Leptogenys processionalis (Jerdon) 

Ponera processionalis Jerdon, 1851, Madras J. Lit. Sci., 17: 103 – 127. 

Body is comparatively robust. This species generally builds temporary nests in loose soil. Ali (1991) states that this species shifts nests quite frequently and often takes shelter under stones and leaf debris, occupy cracks and crevices in foundations of buildings. Population size varies from 7000- 40,000 individuals. Termite constitutes more than 80% of its food.

Distribution: Karnataka, Kerala, Tamil Nadu, West Bengal and nearly the whole of Peninsular India (Bingham, 1903; Tiwari, 1999).

Range: India, Sri Lanka (Bingham, 1903; Donisthorpe, 1942  & 1943; Chapman and Capco, 1951).

Genus 5. Pachycondyla Smith

This is a large and diverse group among the subfamily ponerinae. They nest in soil with diverse feeding and nesting habits. This genus differs from Leptogenys in having non-pecinate claws. It differs from Diacamma in not having spines on the petiole and by the absence of mesopleural cavity. Four species belonging to this genus are known to present on the Indian Institute of Science Campus.

 Key to species

1 Length under 5mm, black, body lightly punctured, legs, antennae, mandibles pale yellow Pachycondyla sp.8 (Brachyponera)
Length over 5mm 2
2. Length 8.5 mm, colour dark reddish brown all over, conical melanaria
Length less than 8.5mm, colour black, node thick in side view 3
3. Length 7mm. Black, antennae, mandibles and legs reddish brown, node thick, body punctured, but not striated crassa
Length 6.5 mm. Black, node not very thick as in crassa, body punctured and striated Pachycondyla sp.4

5.1. Pachycondyla crassa

Ponera crassa Emery, 1877, Ann. Mus. Civ. Stor. Nat. Genova 9: 363 – 381.

Brown reports this species from India. Members of this species have an average length of 7mm. Black in colour with antennae, mandibles and legs reddish brown. This species can be distinguished from other species by the thick node and punctured body.  The nesting habits of this species are not known.

Range: India, Burma and Mindanavo (Brown)

5.2. Pachycondyla melanaria (Emery)

Ponera melanaria Emery, 1893. Ann. Soc. Ent. Fr., 260.

This is the largest of the Pachycondyla species present in our Campus. It has an average length of 8.5 mm. It is dark reddish brown all over, antennae, mandibles and legs lighter. Nesting habits of this species are not known.

Distribution: Chickmagalur (Ali, 1991), Kerala, South and North Kanara (Bingham, 1903).

Range: Sri Lanka, Burma and Singapore (Bingham, 1903; Donisthorpe, 1942; Chapman & Capco, 1951).

5.3. Pachycondyla sp.4 (Museum number)

This is smaller than crassa and melanaria. Itis black in colour and similar to crassa, but differs from it in having the body punctured and striated and not having a very thick node (In P.crassa, the body is punctured and striated and have a very thick node).

 5.4. Pachycondyla (Brachyponera) sp.8 (Museum number)

This was earlier known as Brachyponera, now it is placed under the genus Pachycondyla. This is the smallest of the 4 species available in our Campus. It is a very common species and makes nests in leaf-litter, and crevices of walls etc. There is no recruitment or trail formation in this species.  

Genus 6. Platythyrea Roger

Only one species was collected under this genus. This is a very rare group in our campus. It looks similar to the genus Pachycondyla, but differs from it by the characteristic pruinose appearance of the body and having 2 pectinate spurs (one small and one large) on the hind leg.

6.1. Platythyrea parallela (Smith)

Ponera parallela Smith,1859. J. Proc. Linn. Soc. London Zool., 3: 132 – 158.

Length 7 mm. Black, entire body is covered with dense very short pubescence, which gives a pruinose appearance to the ant. Nests in dead barks of trees ((Ali, 1991.)

Distribution: Bangalore, Chickmagalur, Tarikere (Ali, 1991), Mysore, Bengal and Western India (Bingham, 1903).

Range: India and Aru (Donisthorpe, 1942).