Ascocotyle (Ascocotyle) tenuicollis Price, 1935

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 : 1738-1739

Ascocotyle (Ascocotyle) tenuicollis Price, 1935

(®gure 2)

Metacercaria

Morphology. Aguirre-Macedo and GarcõÂa-MaganÄa (1994: 17; ®gure 7a, b), Scholz et al. (1995: 179; ®gure 3A, C±E) and Scholz et al. (1997a: 163; ®gure 1E±G, I) provided detailed descriptions of metacercariae that can easily be distinguished from those of other Ascocotyle species by combination of the following features: cyst spherical, thin-walled; body pyriform; preoral lobe prominent; posterior appendage long, curved to convoluted, reaching to pharynx or overlapping it; oral sucker with 32 circumoral spines forming two complete rows of 16 spines each; intestinal caeca short, very wide, sacciform, preacetabular, containing discoidal corpuscles; excretory bladder voluminous, ®lled with large lipoid droplets.

Second intermediate hosts. Astyanax fasciatus (Cuvier) , Bramocharax caballeroi Contreras-Balderas and Rivera-Teillery (Characidae) ; Poecilia catemaconis Miller , P. latipunctata Meek , P. mexicana Steindachner , P. petenensis (GuÈnther) , P. velifera (Regan) , Poeciliopsis catemaco Miller (Poeciliidae) ; Cichlasoma argentea Allgayer , C. aureum (GuÈnther) , C. fenestratum (GuÈnther) , C. friedrichstahli (Heckel) , C. geddesi (Regan) , C. helleri (Steindachner) , C. intermedium (GuÈnther) , C. lentiginosum (Steindachner) , C. managuens e (GuÈnther), C. nourissati (Allgayer) , C. octofasci - atum (Regan), C. pearsei (Hubbs) , C. salvini (GuÈnther) , C. synspilum Hubbs , C. urophthalmus (GuÈnther) , Cichlasoma sp. , Petenia splendida (GuÈnther) (Cichlidae) ; Ophisternon aenigmaticum Rosen and Greenwood (Synbranchidae) .

Site of infection. Heart, exceptionally gill arches.

Distribution. Campeche (El Vapor, El Viento, La Pera, Palizada, Rancho II, Santa Gertrudis); Chiapas (Cedros, LacanjaÂ); Quintana Roo (Bacalar, Box Toro, CabanÄas, Cenote Azul, Escondido, FramboyaÂn, La UnioÂn, Laguna Paiyegua, Mahahual, Ramonal, Raudales, RõÂo Hondo); Tabasco (Camellones Chontales, El Espino, Puyacatengo, Santa Anita, Tucta, YumkaÂ); Veracruz (Catemaco, Los TuxtlasÐBalzapote, La Palma, Las MaÂquinas); YucataÂn (CelestuÂn, Chaamac, Chen-haÂ, DzibilchaltuÂn, Mitza, Noc-choncunchey, Sahkaba).

References from Mexico. Aguirre-Macedo and GarcõÂa-MaganÄa (1994); Scholz et al. (1995, 1997a); Salgado-Maldonad o et al. (1997); Scholz and Vargas-VaÂzquez (1998); Vidal-MartõÂnez et al. (2000); present study.

Specimens deposited. CHCM-137, IPCAS D-345.

Adult

Morphology. Scholz et al. (1997a: 163 and 165; ®gure 1A±D, H) described adults from naturally and experimentally infected de®nitive hosts. The adult of A. (A.) tenuicollis from the intestine of Casmerodius albus Linnaeus from PaÂtzcuaro Lake (MichoacaÂn), previously misidenti®ed as A. leighi (CNHE 1532Ðsee Comments) , is illustrated in ®gure 2.

De W nitive hosts. Ardea herodias , Casmerodius albus , Buteogallus anthracinus (Deppe) , Phalacrocora x olivaceus (Humboldt) .

Site of infection. Intestine.

Distribution. Jalisco (Salinas de Careyes), MichoacaÂn (PaÂtzcuaro), YucataÂn (CelestuÂn).

References from Mexico. Aguirre-Macedo and GarcõÂa-MaganÄa (1994); Scholz et al. (1997a); present study.

Specimens deposited. CHCM-361, IPCAS D-344.

Comments. Cichlids are the most suitable second intermediate hosts but ®sh of other families may also harbour metacercariae that are normally encysted within the bulbus of the heart ( Scholz et al., 1997a). Adults have been found in four species of ®sh-eating birds in Mexico, two of which ( A. herodias and P. olivaceus ) are new de®nitive hosts of this parasite. SepuÂlveda et al. (1999) found A. (A.) tenuicollis to belong to the most frequent (prevalence 54%) and numerous (mean intensity of infection 112 specimens; range 1±1260) helminth parasites of Casmerodius albus in Florida.