ON AN ACCOUNT OF INDIAN HEPTAGENllDAE (EPHEMEROPTERA) WITH KEY TO THEIR IDENTIFICATION

Mayflies are amphibiotic insect and represent order Ephemeroptera, which inhabit both lotie and len tic ecosystem of our water. Heptageniidae is one of the family of these insects, which in our country is represented by 13 species under 7 genera. It represents almost one seventh of the whole component of Indian mayflies, others are represented by 77 species under 24 genera and 11 families. This is the third biggest, family among Indian Ephemeroptera. World over this family is represented by 378 species under 28 genera (Table 1, page 144). All the species of this family are endemic to India, though one has extended distribution in orient, thus we have essentially and exclusively oriental element represented under this family. Heptageniidae has 7 species represented in the zone of higher elevation ranging between 1900 to 5297 meters above mean sea level. Ororotsia hutchinsoni Traver (1939) has been recorded as larvae in a lentic fresh water lake at an altitude of 5297 m which happens to be highest elevation record for any mayfly within our limits. Of our 13 Heptageniidse, male of9, female of 12 and larvae of only 1 is known (Table II, page 145), A key has been formulated to distinguish all 7 genera and 13 species of Indian Heptageniids.


INTRODUCTION
Mayflies are amphibiotic insect and represent order Ephemeroptera, which inhabit both lotie and len tic ecosystem of our water.Heptageniidae is one of the family of these insects, which in our country is represented by 13 species under 7 genera.It represents almost one seventh of the whole component of Indian mayflies, others are represented by 77 species under 24 genera and 11 families.This is the third biggest, family among Indian Ephemeroptera.World over this family is represented by 378 species under 28 genera page 144).All the species of this family are endemic to India, though one has extended distribution in orient, thus we have essentially and exclusively oriental element represented under this family.Heptageniidae has 7 species represented in the zone of higher elevation ranging between 1900 to 5297 meters above mean sea level.Ororotsia hutchinsoni Traver (1939) has been recorded as larvae in a lentic fresh water lake at an altitude of 5297 m which happens to be highest elevation record for any mayfly within our limits.Of our 13 Heptageniidse, male of9, female of 12 and larvae of only 1 is known (Table -II, page 145), A key has been formulated to distinguish all 7 genera and 13 species of Indian Heptageniids.

SYSTEMATIC
Heptageniidae is one of the most distinctive family of mayflies represented almost •all over the world by 378 species under 28 genera.Itcomes only next to Baetidae, qualitatively which is represented by 519 species under 17 genera.In contrast Indian Heptageniidae are represented by 13 species under 7 genera.Of these Rhithrogena Eaton has been recorded for the frrst time within our limits (Srivastava & Ray, 1987).Indian Heptageniids, thus, represents only a very small fraction of world's fauna of this group and obviously indicates strong possibility of more representation, as is also true for the whole order, on further detailed investigation of our lotic and lentic ecosystem both at high altitude and plains.
Within Indian sub continent the genus is only represented by another species, R. basin Ali (1971) from Swat, Pakistan.In orient it is represented from Taiwan and Java.
Members of this family are distinguished by following salient points, specially considering our own Heptagennid representatives : These are medium sized mayfly, smallest being Rhithro gena parva with body of male and female measuring respectively 5 and 5.4 mm.While largest recorded is Afronurus solangensis Dubey (1971) with female measuring 18 mm in body length.Eyes of both male and female are separated and do not meet on mid dorsal line, this gap is very narrow in male but in female appreciably wide.Eyes are mostly spherical or ovoid in most of the species but are bean shaped in Afronurus solangensis.Surface between two eyes inwardly arche4 in A. curtus Dubey (1971).In frontal view the head normally looks triangular as in. A. solangensis or in some quadrangular like A. curtus.The head of Ororotsia hutchinsoni Traver (1939) is very distinctively enlarged into prominent lobes which is prominently visible in its frontal aspect This character coupled with both claws are alike, acutely pointed distinguished it from other genera of the family.
Both fore and hind wings may be present This family shares 5 tarsal joint character with Baetidae but differs in well developed network of longitudinal and transverse cross veins in both wings.Cross veins in R. parva are almost transparent but mostly these are' pigmented and in costa and subcosta area thick, dark brown in A. curtus but in this extends to the fork ofRs in Heptagenis nubilia Kimmins (1937).Cross vein to the stigmatic area vary between 9 -16.In O. hutchinsoni it 9 -12, 13 in A. curtus, 14 in Epeorus (Epeorus) lahulensisKapurandKripalini (1963), 16inA.solangensis, and maximum 19 inH.nubilia.There are 5 -6 cross vein in costal space before bula inE.(E.) lahulensis and O. hutchinsoni.Corresponding to the stigmatic area there are 7 -8 cross veins in the sub costal space of the last named species.
Hind wing are generally very small, and may be hyaline or translucent in same sequence as in case of fore wing.The hind wing length to forewing length is related as 6: 12 in A. curtus, 5:16inA. solangensis, 6:13 in C. assamensis, 3:10inE.lahulensis,4:11 in male and 4: 13 in female of H. soiangensis and 1.75 -2 : 8.5 -9 in H. nubila.Costal projection may not be prominent as in A. solangensis, slightly arched outwardly in A. curtus but in E. (E,) lahulensis there is a preminent outward bulge of costal margin.
Fore legs are longer than rest.Tarsus are 5 jointed, all joints are having moveable articulation.Femora of A. curtus are charactersticly curved which is not the case in any other Indian Heptageniids.Claws of each tarsus are similar and out of two claws on each tarsus one is acute, pointed and other is blunt, straight claws of Larvae of O. hutchinsoni have 5 pectinations, incidently this is only Indian Heptageniids whose larva is known.Pigmentation band of dark brown colour present on basal, middle, apical region of femora of E. eatom, E. indicus and H. nubilia.
Abdomen pale to dark brown.In E. eatoni there are redish brown marking of definite pattern while in E. indicus marking of purplish brown on yellow background.E. lahulensis has pale brown to moderate brown but in H. solangensis it is dark brown.Segment I . . .VITI are yellow, IX-X brown in H. nubilia.In male of R. parva I-IX are pale with mid dorsal markings but infemale it is absent Abdomen VII-X are redish brown, besides overlaying olive brown on IX-X in O. hutchinsoni.

Salient taxonomic points of Indian Heptageniids
Genus A.fronurus Lestage (1924) was established with Ecdyonurus peringueyi Esben -Peterson.Within our limits it is represented by two species, A. curtus Dubey and A. solangensis both from riverine ecosystem at the altitude of 2900 and 2800 meters respectively.Genus has no other representative in the Indian Sub region.Fonner of these can be distinguished from latter in small body size (10: 18), smaller forewing (12: 16), smaller hind wing (4:5).Head quadrangular instead of triangular, 13 cross veins to stigmatic area instead of 16, Femora outwardly curved instead of being straight, ovipositor pale yellow, two segmented instead of dark brown single segmented.
Cinygmina Kimmins (1937) is endemic to India and so far has not been recorded for extended distribution.It is represented by its genotype, C. assamensis (=Icinygmina assamensis) from Meghalaya Khasi Hills at much lower altitude of than former genus.By the proportion of foretarsal segment it is distinguished from Epeorus and from Heptagenia by lengthwise ratio of hind tarsal segments.Penes lobes are apically roUnded and are without spines in which it is distinguished from Ecdyonurus, which has lateral dilation.It can be distinguished from Cinygma, not represented in Indian Sub-continent, in having a pair of small thin chitinous plates instead of small spine.
Ecdyonurus Eaton (1968) is well represented genus from much wider zone than previous two genera.Its genotype is Ephemera venosa.Fabricius, by original designation.This genus has 4 representative within our limits namely E. annulifer (Walker, 1860) from Khandala Maharastra, E. bengalensis (Ulmer, 1920) from Darjeeling CN est Bengal) at the altitude of 2178 M., E. eatoni Kimmins (1937), E. indicus Hubbard (1974) both from Khasi Hills (Meghalaya).Member of this genus generally occupy littoral zone under stones in the lotic ecosystem of rivers, streams etc. Body in general, head and thorax in particular are broad, dorsoventraly flat, Genital foreep of E. eatoni is 4 segmented, ochreous, penes lobes fused and swollen at apex with short, incurved stimuli.In contrast in E. indicus it is pale, penes lobes not meeting or fused, constricted at apical half, stimuli are short, strong down curved.' Genus is represented by only one more species in the Indian sub-continent E. islamabadicus Ali (1967).
Epheorus Eaton (1~81) was established with E. torrentium Eaton as its genotype.Within Indian limits it is represented by E. (E.) lahulensis Kapur and Kripalani (1963) from considerable altitude of 3200 m. inhabiting lotic ecosystem of terrential to fast running streams at Sissu, Lahul valley in Himachal Pradesh.The other species of genus represented within our limits was incidently also described from 'Kooloo' (Kulu) Himalaya namely E. psi Eaton (1889).This has extended distribution in Taiwan.There is characterstics abdominal markings on abdomen of later species which is absent in former.In contrast fonner has unlobed penes with short spine present ventrally, just below the apical margin which lacks in latter.Genus has no other additional species represented in the Indian subcontinent.
Heptaegenia Walsch (1963) is rather well distributed genus and has Palingenia flavescens Walsch as subsequent designation (Eaton, 1868).It is represented by two species within our limits -H.nubila Kimmins (1937) from Khasi Hills (Assam) and H. solangensis Dubey (1971) from R. solang,Pir Panel range (Himachal Pradesh) at an altitude of 2800 m.Fonner has 8 mm.body, 8.5-10 mm.forewing while later has 11 mm.body, 11-12 mm forewing, stigmatic area of forewing has 13-16: 19 cross veins and basal2{3 of penes closely opposed, apical lobe dilated outward into truncate expansion without any spine as compared to penes being closely opposed, not only basal side but all along its length, apical lobs simple expansion and with stout spine at base.Genus has only one more representative in the Indian sub-continent H. hazaraensis Ali, (1970), outside orient known to be distributed in Holarctic land Nearctic quite generally distributed.Ororotsia hutchinsoni Traver (1939) was established to accomodate O. hutc hinsoni Traver which has been recorded from North West Himalaya both from lotic ecosytem inhabiting at Pao and lentic ecosystem inhabiting margin of Ororotse Tso lake at considerable altitude of 5297 m.This is highest altitude record for any Indian mayfly.It is characterized by gready expanded frontal margin of head and similar, acutely pointed on each tarsus.This is only Heptageniid within our limits whose larvae are described.Its larvae has its frontal border of head distinctly emarginate at median line.Gills with much reduced fibrillar portion, lamellae flat, broad, roughly rounded and claws have 5 pectinations.Genus is endemic to Indi$, nevertheless it needs further investigation with possibility of more representation, specially at higher aquatic ecosystems of Himalayas.Eaton (1881) is also an established geJlus with Baetis semicolorata Curtis.Within Indian limits it has R. parva (Ulmor) as sole representative which has been recorded by Srivastava and Roy (In press) from Talbadh, Maurbhanj district of Orissa.It is small sized mayfly measming, 5 mm body in male and 5.4 mm in female.Forewing are 7 mm in male and 9 mm in female, cross veins almost transparent, costal margin of wing translucent tinged with yellow.Hind wings are more clear than male.Middorsal abdominal stripe present in male on I-XX, absent in female, claws disimilar.Genus has only other species represented in Indian sub-continent which isR. basiri (1971) described from Swat Pakistan.Genus is also known to occur in Taiwan (Taihorin and Rilcyu Island) and Java.Outside Orient it is distributed in Holarctic and in Nearctic, of general distribution.

ENDEMISM AND mGH ALTITUDE REPRESBNTATION
In our faunal component of mayflies, it is evident from above, that genera cinygmina and Ororotsia are endemic to India as compared to other 5 genera viz., Afronurus, Ecdyonurus, Epesorus, Heptagenia and Rhithrogena have much wider distribution not only in Orient but even beyond it Species wise following 11 species viz.Afronurus curtus, A. solangensis, C. assamensis, EcdyonUTus annulifer, E. bengalensis, E. eatoni, E. indicus, Epeorus (Epeorus) lahulensis.Heptagenia nubilia.H. solangensis Ororotsis hutchinsoni are endemic to India while EpeoTus psi also had endemic origin but has been recorded extended distribution in Taiwan.Only Rhithro gena parva (Ulmer) is not endemic to India, though it has only oriental distribution (Taiwan, Java, India).Thus within family Heptageniidae endemism in 90% (9: 1).This endemism in our mayflies as whole is 5: 1, 75 species out of total 90 species while in other major families like Baetidae this proportion is 29 species out of 35•, Heptageniidae 12 out of 13, Ephemeridae 10 out of 14, Ephemerellidae has all 3 endemic, while Palingeniidae and Polymitarcyidae each one out of 3 endemic, Euthyplociidae, Potamanthidae, Prosopistomatidae, Siphlonomidae each represented by sole species endemic to our limits.1/5 or 18 species of our mayflies are known to have extended distribution in Orient, while one among these viz.-Cloeon inscriptum Bengtsson (Baetidae) has extended distribution, even beyond orient, into Europe.
High altitude representation of Indian Heptageniids is by 7 species above 2000 Meter between range of 2178 -5297 Meters.Of these extreme height is for OroTotosia hutchinsoni which is highest altitude record for any Indian mayflies.Thus little more than 50% ( 7 : 6 ) are high altitude inhabitants and all of these occupy different niches in lotic ecosystem of river, streams etc. Srivastava (1979) has indicated that 1/3 or 31:90 of Indian mayflies are high altitude inhabitants mostly occurring between 3000-4000 Meters inhabiting torrential streams of Himalayan mountain range.

2 .
of Heptageniidae and other families of Indi~ Ephemeroptera & Within each family Endemic Component (R) and with oriental (C) distribution.Shows proportion of Plain (P) and High Altitude (H) Ephemeroptera of India.Among high altitude members family wise relative prepondance of Hepatageniidae and other 6 families are shown.