Arlenelepis harpiprioni gen. et sp. n. (Cyclophyllidea, Dilepididae) is described from the plumbeous ibis Harpiprion caerulescens (Vieillot) (Ciconiiformes, Threskiornithidae) in Province Concepción, Paraguay. This cestode is characterised by a very small body (not exceeding 5 mm in length) consisting of about 30 proglottides, musculo-glandular rostellar apparatus, rostellar hooks arranged in two regular rows, few testes (7-10 in number) situated mostly in a post-ovarian group but one testis pre-ovarian, a large oval cirrus sac reaching antiporal osmoregulatory canals, massive cirrus armed with needle-shaped and thorn-shaped spines, long convoluted vagina, and longitudinally elongate sacciform horseshoe-shaped uterus with deep lobes of the medial uterine wall. The new genus is unique among the family Dilepididae in possessing a rhynchus armed with conical spines.
Chimaerula bonai sp. n. is described from the small Intestine of Phimosus infuscatus (Lichtenstein) in Paraguay. The new species differs from the other two species of Chimaerula Bona, 1994, i.e., Chimaerula woodlandi (Prudhoe, 1960) and Chimaerula leonovi (Belogurov et Zueva, 1968), mainly by the intermediate number of rostellar hooks (30-34 compared to 42-46 in the former and 20-22 in the latter), longer rostellar hooks (31-34 pm versus 26 pm and 19-21 pm, respectively), shorter cirrus sac (58-82 pm versus 158-201 pm and 134-183 pm, respectively) and the absence of rosethorn spines in the cirrus armament. Modifications in the generic diagnosis of Chimaerula are proposed in order to conform it with some peculiarities of the new species (i.e., the relatively small and thin cirrus, the absence of rosethom spines in its armament and the small cirrus sac).
Type material of the proteocephalidean cestodes Manaosia bracodemoca Woodland, 1935 and Paramonticellia itaipuensis Pavanelli et Rego, 1991 (both monotypic genera) as well as recently collected material of the latter species are redescribed. A close similarity between both species was observed: the shape of scoleces is identical, both possess a globular scolex with hidden suckers, a well-developed circular, horseshoe-shaped musculature surrounding suckers; the measurements of both taxa are also similar (scolex, suckers, young proglottides). Both cestodes possess a medullary ovary crossing the dorsal muscle layer and ending in the dorsal cortex, the testes are in the dorsal cortex and the cortical vitellarium is laterally situated. Both species parasitize the same fish host. Therefore Paramonticellia is considered a junior synonym of Manaosia and Paramonticellia itaipuensis becomes a junior synonym of Manaosia bracodemoca. An emended diagnosis of Manaosia, which is a monotypic genus, is provided.
The erythrinid fish Hoplias malabaricus in Paraguay harbour two species of proteocephalid cestodes, Proteocephalus regoi sp. n. and Nomimoscolex matogrossensis Rego et Pavanelli, 1990. The former species differs from most South American members of Proteocephalus from fishes by: 1) presence of a small apical organ, 2) distribution of vitellaria, which do not reach to posterior margin of segment and 3) posterior position of vagina. Nomimoscolex matogrossensis is redescribed on the basis of type and recent material, with emphasis given to the morphology of genital organs and scolex, which possesses an apical organ. Both species possess a dense network of osmoregulatory canals in the postacetabular region of both scolex and neck. Proteocephalus regoi sp. n. is the first representative of the subfamily Proteocephalinae parasitizing erythrinid fish.