Ascocotyle (Ascocotyle) leighi Burton, 1956

Scholz, T., Aguirre-Macedo, M. L. & Salgado-Maldonado, G., 2001, Trematodes of the family Heterophyidae (Digenea) in Mexico: a review of species and new host and geographical records, Journal of Natural History 35 (12), pp. 1733-1772 : 1737-1738

Ascocotyle (Ascocotyle) leighi Burton, 1956

Metacercaria

Morphology. Sogandares-Bernal and Lumsden (1964) did not describe metacercariae found in Mexico.

Second intermediate hosts. Belonesox belizanus Kner , Poecilia sphenops Valenciennes in Cuvier and Valenciennes ( Poeciliidae ).

Site of infection. Heart.

Distribution. YucataÂn (Progreso).

References from Mexico. Sogandares-Bernal and Lumsden (1964).

Specimens deposited. None.

Comments. Sogandares-Bernal and Lumsden (1964) found metacercariae of A. (A.) leighi in two poeciliid ®sh from Progreso, YucataÂn, most probably from CheleÂm lagoon. However, the authors did not provide any data on the morphology of metacercariae.

Metacercariae of A. (A.) leighi are encysted exclusively in the heart and they have been found in poeciliid and cyprinodonti d ®sh in the USA and Mexico ( Burton, 1956; Sogandares-Bernal and Bridgman, 1960; Sogandares-Bernal and Lumsden, 1964). They diOEer from those of A. (A.) tenuicollis encysted in the heart as well mainly in the number of circumoral spines (48±52 in total, i.e. 24±26 in each row, in the former taxon versus 32, i.e. 161 16 in A. (A.) tenuicollis ) ( Burton, 1956, 1958; Scholz et al., 1997a).

Salgado-Maldonad o and Kennedy (1997), and Salgado-Maldonad o et al. (1997) reported metacercariae of A. (A.) leighi from the gills, mesenteries, heart and kidney of several species of cichlids from southeastern Mexico. Although few reference specimens were preserved and available to the present authors, it is possible to assume that most, if not all, metacercariae previously reported as A. leighi were misidenti®ed and belonged to other species of the Ascocotyle- complex. Metacercariae from internal organs of cichlid, characid and poeciliid ®sh were conspeci®c with A. (P). nana and those encysted in the gills of cichlids with A. (A.) nunezae . Metacercariae encysted in the heart of ®sh of diOEerent families might belong to A. (A.) leighi but all voucher specimens examined were conspeci®c with A. (A.) tenuicollis .

Adult trematodes of A. (A.) leighi are not known from Mexico because specimens found in the intestine of Casmerodius albus from PaÂtzcuaro Lake (MichoacaÂn), identi®ed by G. PeÂrez Ponce de LeoÂn as A. leighi ( Lamothe-Argumedo et al., 1997; CNHE 1532), belonged in fact to A. (A.) tenuicollis (®gure 2).