STUDIES ON THE LIFE HISTORY OF , INDIAN DRAGONFLIES , PSEUDAGRION RUBRICEPS SELYS ( COENAGRIONIDAE : ODONATA )

Studies on the larval stages and life history of Indian Odonata are very meagre. Efforts made so far have generally been directed towards the study of adults only. To have a better understanding of the. biology of Indian species in-particular and tropical in general the author has begun a study of the life history of Indian dragonflies from various aquatic habitats. In the present paper life history of Pseudagrion rubriceps Selys, a species widely distributed in Oriental Regions, is described. No detailed account of the biology and larval stages of Indian species of genus PseudagriolJ Selys are available, though brief notes on the subject are to be found by Laidlaw (1915, 1916), Fraser (1924) and Lieftinck (1934). Recently Kumar (1973) has made taxonomic descriptions of the last instar larvae of P. rubriceps Selys and P. laidlawi Fraser.


INTRODUCTION
Studies on the larval stages and life history of Indian Odonata are very meagre.Efforts made so far have generally been directed towards the study of adults only.To have a better understanding of the.biology of Indian species in-particular and tropical in general the author has begun a study of the life history of Indian dragonflies from various aquatic habitats.In the present paper life history of Pseudagrion rubriceps Selys, a species widely distributed in Oriental Regions, is described.No detailed account of the biology and larval stages of Indian species of genus PseudagriolJ Selys are available, though brief notes on the subject are to be found by Laidlaw (1915Laidlaw ( , 1916)), Fraser (1924) and Lieftinck (1934).Recently Kumar (1973) has made taxonomic descriptions of the last instar larvae of P. rubriceps Selys and P. laidlawi Fraser.

MATERIAL AND TECHNIQUES
Studies on the life history in the laboratory were started on 9. ~ i. 1976 by collecting eggs laid in vegetation by a ovipositing female in tandem at a perennial pond at viII.Gorakhpur, Dehra Dun.In the laboratory vegetation with eggs was kept submerged in water in a' glass vessel.Hatching started on 22.vi.76 and completed on 25.vi.76The terminology used for the labium)s that of Corbet (1953), for tibial comb and tarsi that of Mac Neill (1967), and for the anal appendages those of Snodgrass (1954) andMac Neill (1960).still flat and squarish, premental setae 1 + 1, crenations at distal margin of prementum increasing in number; palpal setae 2+2, distal margin of palpus starts forming an outer and inner lobe; movable hook mediumsized; tarsi (Fig. 1 N) 2-segmented, the distal one largest, tibial comb comprises a single tridentate seta; tarsi beset with pectin.atesetae; caudal lamellae (Fig. 1,0) becoming broader with short blunt setae proximally, narrowing distally~ Length 6 mm.
Female gonapophyses further increasing in size, paired processes extend up to anterior side of 9th segment; caudal lamellae have acquired the characteristic shape of the genus Pseudagrion, .ante-and postnodal regions of almost same size,.amedian trachea distinct through whole length of lamella, antenodal region beset with rows of densely arranged spiniform setae; postnodal region bearing a few fine lateral setae, apex napiform (Fig. 2, O).Length 13. 1 mm.
Antennae (Fig. 3A) : 7 -segmented, densely beset with setae; labium (Figs. 3, B-D) -premental setae 1 2 +2 1 , Mid-apical spiniform setae on prementum further increasing in number; palpal setae 4+4, last seta being added at base, movable hook long, narrow outer lobe at distal margin of palpus with 4 teeth, narrow at base, inner lobe larger, pointed and curved, hook-like at apex (Fig. 3-D); number of setae on tibial and tarsi increasing further (Fig. 3E), paired female gonanophyses extend up to 10th abdominal segment; hind wing buds extend as far as end of 2nd abdominal segment; caudal'lamellae further increasing in-size with apex of postnodal half becoming rounded, a row of spiniform setae present on median tracheae in antenodal region (Fig. 3F).Length 16.5 mm.9th I"star (Text-fig.3, G-J): Larvae further increasing in length and beconling darker.Premental setae 1 3 + 3 1, a ;row of lateral and a few spiniform setae present near the base of palpus (Fig. 3 G), palpal setae 4+4; tibial comb comprises a number of densely arr~nged tridentate setae, tarsi with paired rows of pectinate setae; paired female gonapophyses extend as far as 10th segment; caudal lamellae (Fig. 3J) of almost uniform width, ante-and postnodal regions of same size, apex of postnodal region almost rounded.Length 19.2 mm.10th or last Instar (Text-fig.3, K-N) : Yellowish-green to yellowishbrown, mottled with brown dorsally.Premental setae 15+51, spiniform setae also present mid-apically on prementum, and also a row laterally, palpal setae 4+4, distal end of palpus distirict in two lobes (Fig. 3L), movable hook about two-third of the palpus.,Tibial comb (Fig. 3M): comprises a large number of tridentate setae; tarsi beset with pectinate setae.Caudel lamellae (Fig. 3N) fiat, duplex with almost rounded apex: ante nodal region darker than post nodal region and is beset with spiniform setae.The thick median ttachea traverse all along the length of caudal lamellae, from it branch off a number of lateral oblique secondary and tertiary tracheae; length-epiproct 4.62 mm, paraprocts 5.37 mm.Total length 21.5 mm.Seasonal regulation of P. rubriceps is almost identical to that of Cer;agr;on coromandelianum (Fab.)(Kumar, jin press) and a small number of other multivoltine species occurring at Dehra Dun.Larvae are found in temporary and perennial ponds, slow running marshy streams and sometimes amidst shallower water of rivers in plain areas of the valley.
Larval development is rapid and with slight overlapping of broods the species is able to complete at least 3 larval.-generationsin a year.The summer larval broods (i.e., March-April to May-June and June--July to August-September) are completed rapidly in about 2 months time each (cf the breeding record presented in this paper, table 1), thus the first batch of adult emergence in a year occurs in March-April from perenial ponds, oviposition takes place soon after and the 2nd batch of emergence occurs in June-July.A number of ephemeral monsoon ponds are formed during this period as a result of S. W monsoons and these too are now used for oviposition and development of one larval ,generation.The 2nd larval brood is again completed rapidly like the preceeding summer brood and the 3rd batch of adults emerge in September-October.Adults remain on the wing for a while and shortly oviposit either in perennial ponds or in slow running marshy streams.However, with the advent of winter the larval development is slowed down and is completed in about 5-6 months (cf Kumar, in press), the emergence occurs in following March-April thus completing 3 larval generations in a year at Dehra Dun.

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Text-fig.3.-{A-N) Life history of P. rubricaps Selys.(A-F) 8th Instar (A. antenna, B. labium, C. enlarged view distal margin prenentum, D. enlarged view distal margin palpus, E. tibial comb and tarsi, F. epiproct); (O-J) 9th Instar (G.labium, H. enlarged view distal margin of premelltum, I. enlarged view dist~l margin of palpus, J. epiproct); (K-N) 10th Instar (K.labium, L. enlarged view distal margin of palpus, M. tibial comb and tarsi, N. epiproct).BIOLOGY P. ruhriceps Selys is another multivoltine species occurring at Dehra Dun.Adults are common on the wing almost throughout the-year around temporary and perennial ponds and at slow running marshy streams in thick jungles of submontane tracks.Adults generally confine themselves around aquatic biotopes and fly low amidst the vegetation.