Centrocestus formosanu

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 : 1756-1757

Centrocestus formosanu s (Nishigori, 1924)

(®gure 9AÐC)

Metacercaria

Morphology. The most detailed description of metacercariae from Mexico was provided by Arizmendi (1992: 5 ±6; ®gure 3).

Second intermediate hosts. Scholz and Salgado-Maldonad o (2000) reported 39 ®sh species of the following families: Atherinidae , Characidae , Cichlidae , Cyprinidae , Eleotridae , Gobiidae , Goodeidae , Ictaluridae , Mugilidae and Poeciliidae . The eleotrids such as Gobiomorus dormitor LaceÂpeÁde and G. maculatus (GuÈnther) and mugilids such as Agonostomus monticola (Bancroft in Gri th and Smith) were the most susceptible hosts, harbouring up to 6000 metacercariae ( Scholz and Salgado-Maldonado, 2000 Ðtable 2).

Site of infection. Gills.

Distribution. Scholz and Salgado-Maldonad o (2000) listed localities in 10 Mexican states (Colima, Guanajuato, Hidalgo, Jalisco, MichoacaÂn, Morelos, San Luis PotosõÂ, Tabasco, Tamaulipas, Veracruz) where C. formosanus metacercariae were found. Recent ®ndings from RõÂo GrandeÐGuelatao (State of Oaxaca), RõÂo Atoyac and Santa MarõÂa Tecomavaca (Puebla), and Ciudad ObregoÂn (Sonora) extend the distribution of C. formosanus to 13 Mexican states.

References from Mexico. Arizmendi (1992); Amaya-Huert a and Almeyda-Artigas (1994); Salgado-Maldonad o et al. (1995); VeÂlez-HernaÂndez et al. (1998); Scholz and Salgado-Maldonad o (2000), present study.

Specimens deposited. CNHE 3708, IPCAS D-271.

Adult

Morphology. Experimentally recovered adults were described by Arizmendi (1992: 6 ±8; ®gure 4) and Salgado-Maldonad o et al. (1995). Because of some discrepancies between biometrical data of these authors, basic measurements of six hot formalin-®xed specimens are provided: body ¯ask-shaped, 370±460 long and 190±240 wide. Oral sucker 40±47 long and 47±57 wide, armed with a total of 32 circumoral spines arranged in two complete circles of 16 spines each. Anterior spines 10±14 long and 3±5 wide; posterior spines 10±12 long and 3 wide. Prepharynx 12±20 long; pharynx 37±42 long and 27±35 wide. Ventral sucker 42±55 long and 47±55 wide. Sucker ratio 1 5 0.92±1.17. Testes 52±72 long and 60±120 wide. Ovary 45±67 long and 60±112 wide. Seminal receptacle 42±57 long and 45±67 wide. Eggs 32 Ô 2 (27±35; n 526) long and 17 Ô 2 (15±22) wide.

De W nitive hosts. Butorides striatus (Linnaeus) (natural), chicks and mice (experimental).

Site of infection. Intestine.

Distribution. Hidalgo (Tezontepec de Aldama).

References from Mexico. Arizmendi (1992); Amaya-Huert a (1995Ðunpublishe d MSc thesis); Salgado-Maldonad o et al. (1995); Scholz and Salgado-Maldonad o (2000).

Specimens deposited. BMNH 2000.6.1.10, CHCM-245, CNHE 3709, IPCAS D-419, USNPC 88539.

Comments. Centrocestus formosanus was described from Taiwan (then Formosa) and it was imported to Mexico most likely in 1979 (LoÂpez-JimeÂnez, 1987). It has spread rapidly and is now one of the most abundant ®sh parasites in several regions (see Scholz and Salgado-Maldonado, 2000 for review). The thiarid snail of Asian origin, Melanoides tuberculata (MuÈller) , serves as the ®rst intermediate host in Mexico ( Arizmendi, 1992; Salgado-Maldonad o et al., 1995; Scholz and Salgado- Maldonado, 2000).