The chromosome numbers of eleven dragonfly species from Singapore

During a prolonged stopover on the way to the XVIth International Congress of Entomology (Kyoto, Japan), we had time, on July 22, 1980, for some casual dragonfly collecting in Singapore. The collection is of no faunistic interest (cf. M.A. L1EFT1NCK, 1954, Treubia (Suppl.) 22: XIV+202 pp.), but it contains six species that were not previously examined cytologically. while the karyotype of one species appears significantly different from earlier evidence on record. Ictinogomphus decoratus melaenops, Aethriamanta gracilis, Neurothemis fluctuans, Rhodothemis rufa and Rhyothemis triangularis were collected at the MacRitchie Reservoir, The chromosome complements of all of these were hitherto unknown. This is also the case of Orthetrum t. testaceum, gathered along with the five other species mentioned below (inch a population of N. fluctuans) , at the Central Park. The following are brief notes on the male karyotypes of the 11 taxa. Ceriagrion cerinorubellum (Brauer) — n=!4; the relatively large X is the smallest element of the set at I m, there are no m-chromosomes in the two specimens examined. This is at variance with the situation reported from Ballygunge (Calcutta), India (J. DASGUPTA, 1957, Proc.zool.Soc. Calcutta 10: 1-66) where, in addition to a small X, the occurrence of a pair (bivalent) of minute m-elements was reported and figured.