OBSERV A nON ON THE EPICRANIO-ORBITAL COMPLEX OF SOME INDIAN AESHNINAE ( ODONATA : AESHNIDAE )

Diversity of the epicranium resulting from the extent of isolation or contiguity of the compound eyes gained, till date, comparatively little attention in generic or subgeneric classification of Odonates,although such characteristics are of recognised importance in supergeneric classification of the group. Fraser 1936, 1957)mentioned about the presence of extensive variability in the extent of fusion of eyes in the familise Aeshnidae and Libellulidae. Lieftinck (1968) made use of the nature of inter-orbital suture to distinguish various species of Oligoaeschna Selys.


INTRODUCTION
Diversity of the epicranium resulting from the extent of isolation or contiguity of the compound eyes gained, till date, comparatively little attention in generic or subgeneric classification of Odonates,although such characteristics are of recognised importance in supergeneric classification of the group.Fraser 1936Fraser , 1957))mentioned about the presence of extensive variability in the extent of fusion of eyes in the familise Aeshnidae and Libellulidae.Lieftinck (1968) made use of the nature of inter-orbital suture to distinguish various species of Oligoaeschna Selys.
In the present paper, the nature of the epicranio-orbital complex of some Indian Aeshnid dragonflies (division Aeshninae) has been discussed with an attempt to analyse their possible taxonomic significance.

MATERIAL AND METHOD
12 Aeshnid species, representing all but one of the seven known gt?nera and approximately half of the total known species Qf Indian Aeshninae were studied from either or both sexes as repl esented in the named odonate collection of the Zoological Survey of India.Observation was made by placing the specimens under light binocular microscope with objective 1.8 X and eye piece 6.0 X respectively.The specimens were so placed as to produce best clear view of the interorbital suture.Figures were drawn with the help of camera-Iucida drawing apparatus.Attempt has been made to formulate running keys to various genera and species based on the nature of the epicranio-orbital complex.

TREND OF VARIATION OF THE EPICRANIO-ORBIT AL COMPLEX .OF AESHNINAE DRAGONFLIES AS OBSERVED DURING THE PRESENT STUDY
The compound eyes exhibit considerable variation in their shape in different genera and species, varrying from being oval, rounded, oblong or su btriangular, their lateral margin being occassionally deflected variably.Further, the.compound eyes are broadly contiguous with each othe( over the epicranium along the length of the inter-orbital suture that isolates the occiput from other elements of the epicranium like the vertex, vesicle etc.The interorbital suture varies in extent with a reciprocal variation of the extent of the occiput.The apex of the occiput fails, when the occiput is too small, to reach the point of maximum width of the head.The anteromedian margin of the orbit just in front of the interorbital suture also varies from being substraight to deeply arquate in nature.These, are in short, the major trend of variation noticed in course of the present study in respect of the epicranio-orbital complex.KASHMIR, Balli Nala, 11.ix.1964, coli Raj Tilak.
Male : Eyes subtriangular, broader than long, outer margin of eyes suboval with subsqare posterolateral angle.

Records of the Zoological Survey o/India
Female : Eyes globular, longer than broad, outer margin subrounded with feeble median deflection.
Note : The species is recorded here for the first time from Jammu and Kashmir.
Genus Aeshna Fabricius 1775 (Figs. 3 and 4) Vesicle moderately large in comparison to frons, Anteromedian• margin of orbit arquate.Occiput rather large, interorbital suture nearly twice the length of occiput.Eyes oblong, subequal to or shorter th~n frons in width with subrounded outer margin.Apex of occiput falling behind the level of maximum width of head.Eyes equal to and slightly shorter than the frons in width in male and female respectively.Other details as for the genus.

Genus Anax Leach 1815 (Figs. 5 to 9)
Usually vesicle narrow in comparison to frons and anteromedian margin of orbit arquate.Occiput large, interorbital suture 1.29 to 3.20 times the length of occiput.Eyes oval, oblong or subtriangular, subequal to or broader than frons in width.Outer margin of eyes variably suboval and posterolateral angle of the same variably rounded or subsquare.Apex of occiput extending to the level of maximum width of head.

Note:
The species is recorded here for the first time from Punjab and Uttar Pradesh.
1 mm = 14.69 mm Female: Eyes suboval, broader than long (Fig. 8), with lateral margin smoothly oval.Occiput moderately large with concave posterior margin; interorbital suture about twice as long as occiput.
Note : The species has ben recorded for the first time from Punjab.
Female : Eyes subtriangular, broader than long (Fig. 9), with posteriorly deflected outer margin.Occiput large with concave posterior margin.Interorbital suture 1.29 times as long as occiput.Mate : O<;ciput narrower than vesicle in width and a little shorter than the, interorbital suture in length with sinuous posterior margin (Fig. 10).
Female: Occiput subequal to vesicle in width also subequal to the interorbital suture in lingth; posterior margin of occiput squarely produced backwards (Fig. 11).
Note: The species has here been recorded for the first time from the states ot Bihar and Rajasthan in India.Genus Anaciaeschna Selys 1878 (Fig. 12) Vesicl~ moderately large in comparison to frons.Anteromedian margin of eyes deeply arquate.Occiput very small, interorbital suture more than five times the length of occiput. 1 ~yes globular, hroader than frons in wi.dth with nearly rounded outer margin.Apex of occiput falling behind the level of maximum width of head.Female: Occiput very small, shaped as an isolateral triangle.Interorbital suture more than five times as long as the occiput.

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Note : The species has been recorded here for the first time from Arunachal Pradesh and Meghalaya states of the Indian Union.
Note: The species is recorded here for the first time from Meghalaya and the plains of West Bengal.
Genus Gynacantha Rambur 1842 (Figs. 13 to 16) Vesicle rather small in comparison to frons.Anteromedian margin of eyes deeply arquate.Occiput small, interorbital suture.3.5 to 5:5 times as long as occiput.Eyes oval, broader than frons in width.Apex of occiput falling behind the point of maximum width of head.

Male
Eyes broader than long and widest at a point a little below the middle of their length (Fig. 14) G. dravida Lieftinck Eyes as long as wide and widest at a point a little above the middle of their length (Fig. 13) G. bainbri88ei Fraser Female Occiput very small, interorbital suture more than five times as long as occiput (Fig. 16) G. basi8Uttata Selys Occiput larger, interorbital suture less than four times as long as occiput (Fig. 15) G. millardi Fraser Gynacantha bainbriggei Fraser 1922 (Fig. 13) Material studied: 1 0, INDIA: WEST BENGAL, Calcutta, 27.vii. 1972, coH unrecorded.Male: Eyes as long as wide and widest at a point a tittle above the middle of their own length.O~ciput as wide as the vesicle.

Note:
The species has been recorded here for the first time from West-Bengal.Male: Eyes broader than long and widest at a point a littl~ below the middle of their own length; occiput narrower than vesicle in width.
Note : The species has been recorded here for the first time from Northern India.

Note:
The species has been recorded here for the first time from Orissa.