AFFINITIES OF INDIAN NORTH-EASTERN BORDERLAND TERMITES WITH THOSE FROM OTHER PARTS OF THE ORIENTAL REGION

The North-Eastern borderland of the Indian subcontinent includes Assam, Meghalaya, Arunachal Pradesh, Manipur, Nagaland, Mizoram and Tripura in India and also Bangladesh, Bhuta.n and northern Burma. It lies approximately between 88°-98°E longitudes and 22°·29°N latitudes. This region is mainly covered with hills and mountains except for the Brahmaputra Valley in Assam, the eastern extension of the Gangetic Plaiils into Bangladesh and Tripura and the Chindwin and Irrawaddy Valleys in northern Burma. In North it is bounded by eastern Himalayas which curve southwards into Patkai, Naga and Chin Hills in north-south direction, separating India and Burma and extending into the Arakan Y omas in Burma and in its south is the Bay of Bengal. The valleys are fertile, otherwise most of the region is covered with evergreen forests. The central part has Garo and Khasi Hills running in East-west direction in India. The climate of the region is humid tropical and the annual rainfall varies with the situation from approximately, 1250-6500 mm with the highest rainfall in the world received at Cherrapunji (10,625 mm) in Meghalaya, India.


Records oJ the Zoological SurtJey oj 1 nditJ
Indotermitidae (1 genus, 3 species).The number of species known under each of the 32 genera and of those which are endemic or common with India and other parts of Oriental region is given in table 1.The families Mastotermitidae, Termopsidae, Hodotermitidae and Serritermitidae are not represented.
The family Kalotermitidae is known by genera Neotermes, Ol,lptotermes and Oryptotermes.They are all dry-wood termites and of the six species of N eotermes, 4 are endemic to this part, one extends in distribution to North-West to Dehra Dun (U.P., India) and one is common with that from southern India.Glyptotermes is represented by 5 endemic forms and one form common with southern India, and Oryptotermes, which are easily transportable, by two very widely distributed species known also from other zoogeographical regions.
Rhinotermitidae, also \vood infesting termites, are represented by six genera and 13 species.Of the 4 Ooptotermes species, one is endemic, one common with the rest of the Indian subcontinent, one common with eastern India and the remaining portion of the Oriental region, and one extends to eastern India.H eterotermes, reported only by a single species (H.indicola) from Bangladesh, is also very wide-spr~ad in the Indian region above 16 0 latitude and extends through Pakistan to Afghanistan.Reticulitermes is known from this part by 4 species Testricted to colder regions, 3 being end~mic and one common with China.This genus is very well represented in China and extends in its distribution only into this part of the Indian subcontinent.Prorhinotermes and Parrkinotermes are reported by a single species each.The species of the former genus is from southern coastal Bangladesh and is common with that of the Andaman Islands and that of the latter genus from Meghalaya and Arunachal Pradesh, is coomon with China.Schedorkinotermes is known by 2 species both of which are common with those from the Malayan subregion.
Stylotermitidae (genus Stylotermes) is known by 2 endemic species.The genus, however, is mainly Chinese and extends in its distribution along the base of Himalayas to North-West Himalayas with one speci.esreported from southern India.
Termitidae is represented by 77 species belonging to 21 genera.Anoplotermes known by a single species is recorded by Roonwal and Chhotani (1959) form Meghalaya. Eukamitermes with 5 species, has 3 endemic forms and one common with central India and one with remaining parts of the Oriental region.The single species of Synhamitermes is common with the rest of the Indian continent.Microcerotermes with 6 species has 3 endemics, one extending in distribution to N-W Himalaya, and two (same species) are common with Indo-Chinese and Chinese subregions.The species of Angulitermes (3), Dicuspiditermes (2), Pse'Udocapritermes (1), Procapritermes (1), Mirocapritermes (2) and Malaysiocapritermes (1) are all endemics and of the 6 Pericapri-'erme8 2 are endemics, one extending in distribution westwards upto Central India and one upto Dehra Dun (N-W Himalaya) and 2 are common with the remaining portion of the Oriental region East of this part.Of the genus M acrotermes, 4 species are endemic and one is common to this and Indo-Chinese subregions.Odontotermes is the most predominent genus with 18 species, of which 7 being exclusive to this part, 6 common with remaining portion of the whole of the Indian subregion (2 extending in distribution westwards along base of Himalaya), one to be found almost throughout the Oriental region except the Chinese and Malayan subregions, one each is common with Chinese and Malayan subregions and one with Chinese and Indo-Chinese subregions.Hypotermes (3 species) is represendted by a species endemic to this part, a species common with southern India and Sri Lllnka and another, the third species.is widespread to East of this part in the Oriental region.Mictotermes also with 3 species has one endemic, one common with rest of Indian subregion and one well spread allover the oriental region except in the Malayan and Chinese subregions.Ancistrotermes with a single species is known only from this part of the Indian subregion but otherwise is wide spread in the remaining portion of the Oriental region.Of the nasute termites, Bulbi-'ermes with 4 species, has 3 endemics and a species common with Indo-Chinese subregion (Thailand); Ahmaditermes with a single endemic species; Hospitalitermea with one endemic and 3 common to this part and Thailand ; and N asutiterrnes has 8 endemics.
Indotermitidae with the single genus Indote1'mes, is known by 3 species, all exclusive to this part.

ZOOGEOGRAPHY AND APFINITIES
The Oriental zoogeographicql region has been divided into four subregions, i. e. Indian (India, Sri Lanka, Pakistan, Bangladesh Bhutan, Nepal and Burma), Indo-Chinese (Thailand, Laos, Kampuchea and Vietnam), Chinese (Southern China and Taiwan) and Malayan (Malaysia, Singapore, Indonesia and the Philippines), for showing affinities and distribution of the genera found in the North-eastern borderland of the Indian sub-continent (Table 2).
Of the 21 Kalotermitid genera known from the world and 9 from Oriental Region only 3 primarily cosmotropical genera are reported.
The Rhinotermitidae, known by 13 genera from all over the world, is represented by the cosmotropical Ooptoterme8 and Heteroterme8, the essentially palaearctic Reticulitermes, the mainly oriental Parrhinotermes, the generally insular and mainly oriental Prorhinotermes and Schedorhinotermes which is mainly Oriental but is also reported from the Australian, Papuan and Ethiopian regions.The highly competitive and successful genus Ooptotermes is very common.H eterotermes, otherwise well established in the Indian subregion, is reported only from Khulna in Bangladesh and forms the easternmost limit of distribution of the species H. inaicola.Parrhinotermes is found only in this part and its absence in the main Indian subcontinent shows the western-most limit of this mainly Oriental genus which is otherwise quite well known in the malayan subregion.Prorkinotermes confined to islands and coastal regions, has a species reported only from southern coastal Bangladesh and is common with that of Andaman Islands.Schedorkinotermes has two species common with the Malayan subregion; it is supposed to have evolved in the Oriental region but its absence from the intervening main Indian subcontinent and presence again in the Ethiopian region is puzzling.
Of the 21 genera of Termitidae found in this part, Anoplotermes is confined to this part and Euhamiterme8, endemic to the Oriental region, is reported from all the four subregions.The record of Synhamitermes, which is endemic to the Indian subregion, shows the easternmost limit of the genus.Microcerotermes which is well established allover the tropics, Angulitermes and Pericapritermes which are wide spread in the Oriental and Ethiopian regions and the Oriental genera Dicuspiditerme8, Procapritermes, Pseudocapritermes, Mirocapritermes and Malaysiocapritermes are expected to occur.But a number of genera such as Eurytermea, Speculitermes, DOoflitermes known from India and also a number of very common genera such as Globitermes, which is well established in the Indo-Chinese and Malayan subregions, .Amitermes which has a wide distribution in the Australian and Ethiopian regions and also reported from N-W India and the Indo-Chinese and Malayan subregions, and Homallotermes known from the Malayan and Chinese subregions and southern India, are not to be found here.Macrotermes common here and in the East of this part and the Ethiopian zoogeographical region with a species reported from southern India and the eastern coast of Orissa (India) is absent in the remaining portion of the Indian subcontinent, it is rather anamolous in distribution and same is true of .Ancistrotermes as it is found here and in further East and in the Ethiopian Region.Odontotermes and Microtermes, well represented both in the Oriental and Ethiopian zoogeographical regions, are widespread all

+ + +
In Indian region only in N -E borderland through the Orient.Hypotermes is found here and in East of this part" and in southern India and Sri Lanka but is absent in the remaining part of the Indian subregion, this is an another anomally in distribution.This part of the Indian subcontinent is the westernmost limit of Bulbitermes, Akmaditermes and Aciculitermes.N asutitermes, a cosmotropical genus, is of course expected to be found and the Hospitalitermes distribution in the Indian subregion is somewhat similar to that o( Hypotermes.A number of nasute genera found in the Indo-Chinese and Malayan subregion have restricted distributions and do not occur here. The Indotermitidae is known from this part, Thalland and YunnaQ' and Hainan (southern China) and is essentially Oriental.

DISCUSSION
From the above data of distribution it is observed that none of tho' genera are endemic to the North-eastern Borderland of the Indian region \ out of the 109 species recorded as many as 63 (i.e. 57.8 per cent) art.. endemic.In respect of the termite fauna. of remaining part of tb,.Indian subcontinent, 14 species are common to rest of the Indil.Dl subregion, 2 to eastern India, 5 to North-West belt along base ot Himalaya, one to the Andaman Islands and 3 to southern India, alone i and in respect of the remaining parts of the Oriental zoogeographical region, 6 species are common to whole of the region, 12 to Indo-Chinese, 7 to Chinese and 4 to Malayan, subregions.The absence of Schedorhinotermes (Rhillotermitidae) and A ncistrotermes (T ermitidae : Macrotermitinae) in the remaining parts of the Indian subregion and the absence of Bomallotermes, Pseudocapriterme8 and Procapriterme8 (Termitidae : Termitinae), Macrotermes and Bypotermes (Termitidae: Macrotermitinae) and Hospitalitermes (Termitidae : Nasutitermitinae) in the remaining portion of the Indian subregion except southern India and also Sri Lanka and the presence especially of Homallotermes, Pseudocapriterme8 and Procapritermes in the western portion of southern India are some of the anomalies in the distribution of these genera.In explanation of this, it may be mentioned that Schedorkinotermes and Macrotermes had a continuous distribution through the Indian subcontinent to the Ethiopian zoogeographical region, and Homallotermes, Pseudocapritermes, Procapritermes, Hypotermes and Hospitalitermes got distributed through this part to southern India and including Sri Lanka for Hypotermes and H08pitalitermes.It may be inferred that this Northeastern Boderland has been an important passage for to and fro transit of termites and that the flow of fauna has been through this part and in two directions one along the base of Himalaya and the other southwards; simUarly from North-West some elements diverged southwards and some through this passage further East and South-east as suggested by Kurup (1974) for mammals and Mani (1974).Chhotani (1975a, 1977 andin press) has discussed the origin and distribution of Oriental genera in some detaU t It may, however, be added that the present-day distribution suggests a probable continuity 'of tropical rain-forest conditions and that the discontinuous distribution is due to subsequent ecological changes.Since a number of genera and species are endemic to this part and further South-East, this region can be termed as a favourable seat of evolution for termites.High degree of endmicity, indicative of high rate of speciation, as suggested by Roonwal & Chhotani (1965) for termites of Assam region, is due to (i) favourable ecological conditions i. e., dense evergreen forests and (ii) low migration pressure du~. to e.cological discontinuity to the West of this region and high ranges and valleys which restrict the movement of certain termites cutting them into small and me~i~m sized populations contind to some pockets. .

SUMMARY
The North-eastern borderland of the Indian subcontinent includes the north-eastern states in the Indian Union and also Bangladesh, Records 0/ tke Zoological SurtJey oj /nil;a Bhutan and northern Burma.Termites of this part are known by 109 species belonging to 32 genera distributed in the families Kalotermitidae, Rhinotermitidae, Stylotermitidae, Termitidae and Indotermitidae.The distribution and zoogeography of these termites and their affinities with those from the other parts of the Oriental zoogeographical region are discussed.It is suggested that through this part of the Indian subcontinent there has been to and fro transit of termites, that this part and the area further East and South-east of it can be termed as a favourable seat of evolution for termites since a number of species and genera are endemic to this region and that discontinuous distribution of certain genera is due to subsequent changes.
Indian subregion and other parts of Oriental region

TABLE i .
Distribution of India.nNorth-eastern Borderland termites in different subregions of Oriental Region