Pygidiopsis pindoramensi

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 : 1764-1766

* Pygidiopsis pindoramensi s ( Travassos, 1929)

(®gure 12)

Metacercaria

Morphology. (Morphology based on 12 metacercariae from Poecilia catemaconi s, three from Xiphophorus helleri Heckel and one from Poecilia mexicana ; measurements of ¯attened specimens ®xed with GAP in parentheses.) Cyst widely oval to almost spherical, (230±340) long and (230±310) wide, with thick external wall and thin, hyaline internal wall. Body pyriform, 280±370 (500±650) long and 150±280 (250±310) wide, covered with scale-like tegumental spines, with convex base and serrate distal end, overlapping one another. Spines covering almost completely ventral side except for small area around subterminal excretory pore; dorsally spines reaching only to testicular level. Remnants of eye-spots at pharyngeal level. Oral sucker spherical, without posterior appendage, 30±38 (42±58) long and 30±40 (42±57) wide, with one complete row of 16 ®ne circumoral spines and four additional spines on dorsal side. Prepharynx 36±67 (32±97) long; pharynx oval, 26±32 (38±47) long and 20±28 (37±45) wide; oesophagus longer than prepharynx. Intestinal caeca long and narrow, surrounding ventral sucker, slightly curved medially in posterior part, reaching to ovarian level and containing discoidal corpuscles. Ventral sucker spherical, slightly postequatorial, 32±37 (48±71) long and 37±43 (60 ±65) wide. Sucker ratio 1 5 1.00±1.28 (1 5 1.09±1.42). Testes symmetrical, close to posterior extremity, 23±35 (34±74) long and 24±45 (44±75) wide. Ventrogenital sac formed, anterosinistral to acetabulum, containing widely oval gonotyl with 13±17 narrow refractile bodies. Mouth of ventrogenital sac irregularly oval, opening anteroventral to cavity of ventral sucker. Ovary almost spherical, posterior to acetabulum, 18±25 (25±52) long and 26±31 (33±55) wide. Primordia of vitelline follicles forming two bands lateral to testes between ventral sucker and posterior extremity. Flame cell pattern 2 [(21 2)1 (21 2)] 516. Excretory bladder Y-shaped with short and wide arms or X-shaped with feebly developed posterior lobes, ®lled with numerous small, dark granules. Excretory pore subterminal.

Second intermediate hosts. Poecilia catemaconi s, P. mexicana , Xiphophorus helleri. ( Poeciliidae ).

Site of infection. Gill arches, heart, fatty body.

Distribution. Veracruz (Balzapote, Catemaco).

References from Mexico. Present study.

Specimens deposited. CHCM-355, CNHE 3933, IPCAS D-444.

Comments. Metacercariae of P. pindoramensis were previously found in the mesentery and ovary of cyprinodonti d ®sh Phalloceros caudimaculatu s (Hensel) and Cnesterodon decemmaculatus from Argentina (Ostrowski de NuÂnÄez, 1974).

Ostrowski de NuÂnÄez (1976) reported cercariae of P. pindoramensis from the prosobranch snail Littoridina piscium d’Orbigny from Argentina. The same author (Ostrowski de NuÂnÄez, 1996) described another species of Pygidiopsis , for which the name P. australis was proposed. This species cannot be distinguished in metacercarial or adult stage from P. pindoramensis and diOEers only in cercarial morphology (the arrangement of penetration glands and the absence of pigment granules).

Since the actual distribution of P. australis is not known and P. pindoramensis has been reported from North and South America (see Ostrowski de NuÂnÄez, 1996), the specimens from Mexico are tentatively considered to belong to the latter species.