Ascocotyle (Phagicola) nana Ransom, 1920

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 : 1753-1754

Ascocotyle (Phagicola) nana Ransom, 1920

(®gure 1G)

Metacercaria

Morphology. Metacercariae were described by Salgado-Maldonad o and Aguirre- Macedo (1991: 396±398, 400; ®gure 2), Aguirre-Maced o and GarcõÂa-MaganÄa (1994: 19±20; ®gure 8a, b; all as Phagicola angrense ), Scholz et al. (1995 Ðas Ascocotyle (Phagicola) sp. 2: 181±182; ®gure 6, 7A) and Scholz et al. (1997a: 168; ®gure 3D±J). The most typical characters are pyriform shape of body; indistinct preoral lobe; very short posterior appendage; ®ne circumoral spines forming one complete row of 16 (exceptionally 15 or 17) spines and four (rarely three to six) additional spines; long intestinal caeca curved medially around ventral sucker and reaching to excretory bladder; and well-developed gonotyl with numerous (about 15) refractile bodies ( Scholz et al., 1997a).

Second intermediate hosts. Astyanax fasciatus (Characidae) ; Cichlasoma argentea , C. aureum , C. belone (Allgayer) (5 C. coeruleus (Stawikowski and Werner)) , C. fenestratum , C. friedrichstahli , C. geddesi , C. helleri , C. intermedium , C. managuense , C. meeki , C. nourissati , C. octofasciatum , C. pasionis , C. pearsei , C. salvini , C. synspilum , C. urophthalmus , Petenia splendida (Cichlidae) ; Gambusia yucatana , Poecilia petenensis , P. velifera , Xiphophorus sp. (Poeciliidae) .

Site of infection. Intestinal wall, gonads, liver, kidney, spleen, mesenteries, muscles, swimbladder, rarely gills, heart and brain.

Distribution. Campeche (ChampotoÂn, El Vapor, El Viento, Estero Pargo, La Pera, Palizada, Santa Gertrudis); Chiapas (Cedros); Quintana Roo (Box Toro, CabanÄas, Cenote Azul, Escondido, Gran Cenote, La UnioÂn, Laguna Guerrero, Laguna OcoÂn, Los Cuates, Mahahual, Noh-Bek, Ramonal, Raudales, RõÂo Hondo, Valle Hermoso); Tabasco (BalancaÂn, Camellones Chontales, El Espino, El Guanal, El Yucateco, Jonuta, Las Ilusiones, Puyacatengo, Teapa, Tenosique, YumkaÂ); Veracruz (Catemaco); YucataÂn (CelestuÂn, Chaamac, Chek-haÂ, Chen-haÂ, DzibilchaltuÂn, Dzonot Cervera, FramboyaÂn, Hodz-ob, Mitza, Noc-choncunchey, Petentuche, Progreso, RõÂo Lagartos).

References from Mexico. Salgado-Maldonad o and Aguirre-Macedo (1991); JimeneÂz-GarcõÂa (1993); Aguirre-Macedo and GarcõÂa-MaganÄa (1994Ðall authors as Phagicola angrense ); Scholz et al. (1995 Ðas Ascocotyle (Phagicola) sp. 2); Salgado- Maldonado et al. (1997); Scholz et al. (1997a); Scholz and Vargas-VaÂzquez (1998); Vidal-MartõÂnez et al. (1998, 2000); present study.

Specimens deposited. CHCM-123, CNHE 3728, IPCAS D-341, USNPC 90194.

Adult

Morphology. Adult worms from Mexico were described and illustrated by Salgado-Maldonad o and Aguirre-Macedo (1991), Aguirre-Macedo and GarcõÂa- MaganÄa (1994: 20; ®gure 8c), and Scholz et al. (1997a: 168 ±170; ®gure 4). Scholz et al. (1997a) counted 161 4 circumoral spines in most (70%) of specimens studied; only a few trematodes possessed diOEerent spination patterns (141 4; 151 4; 161 5; 161 6; 171 4; 171 5).

De W nitive hosts. Ardea herodias , Buteogallus anthracinus , Casmerodius albus (natural), chicks, laboratory mouse (experimental).

Site of infection. Intestine.

Distribution. YucataÂn (CelestuÂn).

References from Mexico. Salgado-Maldonad o and Aguirre-Macedo (1991); Aguirre-Macedo and GarcõÂa-MaganÄa (1994)Ðall as Phagicola angrense ; Scholz et al. (1997a); present study.

Specimens deposited. CHCM-359, IPCAS D-340, USNPC 86809, 90195.

Comments. Cichlids, in particular Cichlasoma urophthalmus , are the most suitable hosts of this trematode that belongs to the most widely distributed species of ®sh parasites in southeastern Mexico. Its metacercariae are also common in perciform ®sh in the northern part of the Gulf of Mexico (Mississippi, Florida) ( Font et al., 1984b).

Comments. The type host of A. (P.) nana is the arctic fox, Alopex lagopus (Linnaeus) , and several mammals such as opossum, raccoon, Syrian hamster or mouse have been reported as experimental hosts ( Ransom, 1920; Font et al., 1984b). However, most adults obtained from natural de®nitive hosts were found in ®sheating birds such as Ardea herodias , Buteogallus anthracinus , Casmerodius albus , Ixobrychus exilis (Gmelin) and Sula bassana (Linnaeus) ( Font et al., 1984b; Salgado- Maldonado and Aguirre-Macedo, 1991; Scholz et al., 1997a; SepuÂlveda et al., 1999). Cercariae of A. (P.) nana were found in the snail Pyrgophorus coronatus from YucataÂn ( Ditrich et al., 1997).