The hitherto known records of Orthetrum trinacria in Spain were reviewed by FJ. OCHARAN LARRONDO (1987, Los odonatos de Asturias y de Espana: aspeclos sislematicos y faunisticos. Mem. Doctor Biol., Univ. Oviedo). During two consecutive years we have conducted observations on this species at diverse points in northern Extremadura, where a particularly stable population was discovered at the "El Robledo" Reservoir, in Malpartida de Plasencia, Ciceres (U.T.M. 30TTK.4334). Since ovipositing females and tenerals were often observed, we have undertaken a systematical collection of the anisopteran exuviae in order to ascertain the local autochthony of this species. In all, 121 exuviae were gathered, among which 32 are referable to O. trinacria, viz. — 13-V11-86: Anax imperator Leach (I), Tritemis annulata (P. de Beauv.) (2), Orthetrum cancellatum (L.) (2), O. trinacria Sel. (8); — 22-V11I.86: A. imperator (1), T. annulata (2); — I4-IV-87: Gomphus pulchellus Sel. (1); — 3-V-87: A. imperator (10), G. pulchellus ( (1), Crocothemis erythraea (Bridle) (1), O. cancellatum (2), O. trinacria (1); — I0-VI-87: A. imperalor (5), G. pulchellus (3), C. erythraea (4), T. annulata (1), O. cancellatum (3), O. trinacria (10); — 2I-VI-87: A. imperalor (2), G. pulchellus (I) C. erythraea (5), O. cancellatum (4), O. trinacria (12); — 17-VII-87: A. imperalor (3), G. pulchellus (II) C. erythraea (2), T. annulata! 18), O. cancellatum (3), O. trinacria (1); — 6-VIII-87: G. pulchellus (1).