International Journal of Odonatology 1 (1) 1998. © 1998 Backhuys Publishers.

Acknowledgements

The assistance of Dr M.J.Parr in identifying Orthetrum kristenseni and lending papers concerning the Italian expeditions is gratefully acknowledged.

References

Brignoli, P.M., C. Consiglio, V. Cottarelli & A. Vigna Taglianti, 1978. General Remarks about the first and second Zoological Expeditions to . Problemi attuali di Scienza e di Cultura Quaderno no 243: S-26. Accademia Naz. dei Lincei. Consiglio, C.,1978. collected in Ethiopia by the Expeditions of the Accademia Naz. dei Lincei. Introduction and Zygoptera. ibid: 27-52. Dumont. H.J., 1983. On the of the Ethiopian Plateau and Lake Tana. Notulae Odontologicae 2: 10-11. Pinhey, E. C. G., 1961. A Survey of the Dragonflies (Order Odonata) of Eastern Africa. Trustees of British Museum. Pinhey, E.C.G. 1970. A New Approach to African Orthetrum (Odonata). Occ. Pap.Nat. Museum Rhodesia 4 (30B): 261-321. Pinhey, E.C.G., 1981. Odonata collected in Ethiopia III, Anisoptera. Quaderno no. 252: 5-56. Accademia Naz. dei Linzei. Ris, I. 1911. Zwei neue Afrikanische Arten der Libellulen-Gattung Orthetrum. Rev. Zool. Afr. 1: 125-131.

TETRATHEMIS POLLEN!, ITS REPRODUCTIVE BEHAVIOUR AND PREFERRED HABITAT. by Jill Silsby

1, Haydn Avenue, Purley, Surrey, UK

A colony of Tetrathemis polleni was observed frequently over a period beginning 07 and ending 12 February 1998. The site was a pond (c. lOft x 15ft) situated some 50 yards from the Sabie River at Hazyview in Eastern Transvaal, Republic of (S25o 01.722, E 013o 08.100, altitude 1075ft). It was a small, dirty pond overhung by a large Matumi Tree (Breonadia salicina) and with several small patches of reedmace growing a foot or so in from the perimeter. By 11am the pond was always teaming with odonates: two species of Orthetrum and two of Trithemis were present as well as lucia, Ceriagrion glabrum, a number of other ceonagrionid species and, interestingly, very small numbers of another tetrathemine, Notiothemis jonesii. From this time onwards, male Tetrathemis polleni began to descend from the overhanging branches of the Matumi Tree, each individual settling on the tip of a particular piece of reedmace which became his territory. There was constant, somewhat dilatory, activity as territory holders saw off new arrivals and, in so International Journal of Odonatology 1 (1) 1998. © 1998 Backhuys Publishers. 97 doing, invaded the territory of a neighbour thus provoking further fluttery objection. But then a female would appear "out of the blue", at which moment every perched male took to the air and frantic activity followed. By the time everything had quietened down it could be observed that one of the males, without any apparent courtship, had been successful in capturing a female and that the pair was already copulating. The act of copulation took just 20 to 30 seconds and, immediately following release, the female (the wings of which sometimes bore paler versions of the males' dark patches but more often did not) commenced oviposition. Although E.C.G. Pinhey (1961) suspected otherwise (due to the structure of the female's ovipositor), it is generally accepted that females of the genus Tetrathemis, unlike other libellulids, lay their eggs in clutches onto the surface of a piece of vegetation (or even, according to Jochen Lempert in his MSc thesis (1988), onto a thread of a spider's web!). Certainly, in the case under discussion, females released clutches of yellow eggs onto the underside of their mates' blades of reedmace. As the female released her eggs the male, with much fluttering of his wings, flew frenetically round the leaf, pausing every now and then to perch just above his labouring mate. As soon as ovipostion was complete, the female flew up into the tree above and the male returned to his post on the tip of his blade. The clutches of tiny eggs adhered to the underside of the leaf surface and the blades of the more successful males were bedecked with these small masses of ova in varying degrees of freshness. When examined with a magnifying glass, it could be seen that eggs in clutches that had been deposited more than two days previously were broken, the hatchlings having presumably dropped into the water below. T. polleni is by no means common in South Africa but a suitable site is instantly recognisable and very predictable. A small, dirty piece of stagnant water, almost totally overshadowed by a broad-leafed tree and situated in the vicinity of a fast moving stretch of running water should lead the observer to suspect it could be inhabited by this very lovely African libellulid.

References

Lempert, J., 1988. Untersuchungen zur Fauna, Okologie und zum Fortpflanzungsverhalten von Libellen (Odonata) an Gewassern des tropischen Regenwaldes in , Westafrika. Aus dem Institut fur Angewandte Zoologie der Universitat Bonn. Pinhey, E.C.G., 1961. A Survey of dragonflies (Order Odonata) of Eastern Africa.