(14931) CHESALMAH, M.R., S.T.S. HASSAN, A. ABU HASSAN & A,B. ALI, 1998. Influence of physical and chemical factors on the larval abundance of Neurothemis tullia (Drury) (Odonata: Libellulidae) in a rain fed rice field. Hydrobiologia 389:193-202. – (First Author Sch. Biol. Sei., Univ. Sains Malaysia, 11800 Kinden, Penang, Malaysia). The influence of pH, temperature, conductivity, dissolved oxygen, nitrate, phosphate and chlorophyll a on a larval population in Bandar Bara distr. Peninsular Malaysia was studied. Water availability was the main factor determining the presence or absence of larvae in the rice field. Pesticides and fertilizer applications resulted in low population densities. None of the physical and chemical factors measured in this study affected the abundance of N. tullia. Rapid larval population build-ups were observed soon after chemical applications or spells of dry periods, reflecting continual oviposition and hatching of eggs. (14932) GONZALEZ SORIANO, E. & R. NOVELO GU TIERREZ, 1998. Oplonaeschna magna sp. nov. (Odonata: Aeshnidae) from Mexico with a description of its larva. Revta Biol. trap. 46(3): 705-715. – (First Author: Depto Zool., Inst. Biol,, UNAM, Apdo Postal 70-153, MX-04510 Mexico, D.F.). Both sexes and final instar larvae are described and illustrated. Holotype d: Morelos state, Tepoztlän, 4-XI-1990; deposited in CNIN (UNAM, Mexico). A description of O. armata larva is also provided, and the features separating the 2 spp. are outlined. Notes on the biology of the new sp. are included.