María Celina Digiani

Redescriptions of the Nematodes Litomosoides patersoni (Mazza, 1928) (Onchocercidae) and Stilestrongylus stilesi Freitas, Lent, And Almeida, 1937 (Heligmonellidae) Parasites of Holochilus chacarius (Rodentia, Cricetidae) From Salta, Argentina

Abstract Two nematode species are redescribed from the type host species Holochilus chacarius Thomas (Rodentia, Cricetidae, Sigmodontinae) and from the type locality of 1 of them, i.e., Ingenio San Martín de Tabacal, Salta Province, Argentina. Rodents were deposited at the Colección Mamíferos Lillo, Tucumán, Argentina. Litomosoides patersoni (Mazza, 1928) (Onchocercidae) possesses a buccal capsule with irregular external walls, a buccal cavity smooth, becoming thinner near the oral opening, a complete set of head papillae, 3–6 pairs of cloacal papillae, and the “sigmodontis” type of spicules. Filarioids were found in 3 of 17 examined hosts. Stilestrongylus stilesi Freitas, Lent, and Almeida, 1937 (Heligmonellidae), whose description was based on male specimens, was found in all 17 of the examined hosts. Here, we describe the female and the synlophe of both sexes. Females are characterized by a short uterus with less than 25 eggs, short ovejector, short and conical tail, and the posterior extremity strongly invaginated in a cuticular expansion usually harboring 1 to several eggs. The synlophe is characterized by 29–31 sub-equal cuticular ridges at the mid-body, with single (in males) or double (in females) axis of orientation of the ridges. The present work validates and enlarges the original descriptions of both species and assigns the specimens from L. patersoni, recovered from the type locality and the type host species, as neotypes.

New reports and a redescription of Porrocaecum heteropterum (Diesing, 1851) (Ascarididae), a rare nematode parasitic in South American threskiornithid birds1

Porrocaecum heteropterum (Diesing, 1851) (Nematoda, Ascarididae) is reported parasitising the white-faced ibis Plegadis chihi and the black-faced ibis Theristicus melanopis melanopis (Ciconiiformes, Threskiornithidae) from the Provinces of Buenos Aires and Neuquén, Argentina. This nematode has been reported very few times in the literature, mainly from Brazilian threskiornithids, and there have been no new reports following a redescription of the species given in 1957. This paper provides new host and locality records for this rather rare species, as well as some additional morphological data, mainly based on SEM studies, which complement the previous descriptions. The scarce and sporadic records of this species seem to indicate not only a defined host-specificity towards threskiornithid birds but also that the acquisition of this parasite is possible only when certain ecological barriers, including food availability, feeding habits and environmental conditions, are surmounted.

The systematic position of some nippostrongyline nematodes (Trichostrongylina: Heligmosomoidea) parasitic in Argentinean sigmodontine rodents

The systematic position of two nippostrongyline nematodes described from Argentinean sigmodontine rodents is clarified. The first species, Hassalstrongylus multiovatus Suriano & Navone, 1992, parasitic in Akodon simulator Thomas from the province of Tucumán, was studied on the basis of type and voucher material. H. multiovatus is proposed as a junior synonym of Trichofreitasia lenti Sutton & Durette-Desset, 1991, a parasite described from Oligoryzomys flavescens (Waterhouse) in the province of Buenos Aires. The holotype and three of seven paratypes deposited as H. multiovatus were identified as T. lenti. One male paratype was identified as Guerrerostrongylusuruguayensis Sutton & Durette-Desset, 1991, a parasite described from O. flavescens in Uruguay. Three female paratypes were identified as Guerrerostrongylus sp. The second species, Stilestrongylus scapteromys Suriano & Navone, 1996, parasitic in Scapteromysaquaticus Thomas from the province of Buenos Aires, was studied on voucher material. Stilestrongylus scapteromys and Malvinema frederici Digiani, Sutton & Durette-Desset, 2003, the type-species of Malvinema Digiani, Sutton & Durette-Desset, 2003, were described from the same host and geographical region. As they are considered to refer to one and the same taxon, the new combination Malvinema scapteromys n. comb. is proposed for this species.

SYSTEMATIC POSITION OF SOME NEARCTIC HELIGMOSOMOIDEA (NEMATODA: TRICHOSTRONGYLINA) FROM THE U.S. NATIONAL PARASITE COLLECTION AND THEIR DESCRIPTION

The systematic position of some heligmosomoid nematodes from rodents, deposited in the U.S. National Parasite Collection (USNPC), is revised, mainly through the study of their synlophe, which in all cases was unknown or insufficiently described. The material was registered as different species of Longistriata Schulz, 1926, a genus whose representatives are only parasitic in Holarctic insectivores. Longistriata norvegica Dikmans, 1935, parasitic in Rattus sp. becomes a synonym of Hassalstrongylus aduncus (Chandler, 1932). Specimens registered as Longistriata dalrymplei Dikmans, 1935, from Ondatra zibethicus, are confirmed to belong to Carolinensis (Travassos, 1937). Specimens registered as Longistriata noviberiae Dikmans, 1935, parasitic in Sylvilagus floridanus alacer, were found to belong to Vexillata, and Vexillata noviberiae n. comb. is here proposed. This is the first record of a species of Vexillata in a lagomorph. Other specimens registered as Longistriata norvegica, parasitic in Geomys floridanus austrinus, were also found to be an undescribed species of Vexillata (Hall, 1916), which is named Vexillata chitwoodi n. sp. This is similar to Vexillata chabaudi Yoyotte-Vado, 1972, Vexillata petteri Durette-Desset, 1970, Vexillata scorzai Guerrero, 1984 and Vexillata tejerai Guerrero, 1984, all having the same number of cuticular ridges (4 dorsal, 5 ventral) and the division of the dorsal ray at its apex. The most related species is V. chabaudi, which is differentiated from the new species by rays 4 not curved distally, by thick rays 8, and by a dorsal ray enlarged at the level of the arising of rays 8.

A NEW GENUS OF NIPPOSTRONGYLINAE (NEMATODA: HELIGMONELLIDAE) FROM THE WATER RAT SCAPTEROMYS AQUATICUS (SIGMODONTINAE) IN ARGENTINA

A new genus of Nippostrongylinae, Malvinema n. gen., with 3 coparasitic species M. frederici n. sp., M. carolinae n. sp., and M. victoriae n. sp. from the intestine of the water rat, Scapteromys aquaticus Thomas (Rodentia: Muridae), from the northeast of Buenos Aires Province, Argentina, is proposed in this study. The new genus shows similarities to 2 Neotropical Nippostrongylinae: Carolinensis (Travassos, 1937) by some characters of the synlophe and Stilestrongylus Freitas, Lent and Almeida, 1937, by the pattern of the caudal bursa. It is characterized by a synlophe with triple or quadruple gradient of size of the ridges, lateromedian, decreasing from the largest left and right ridges. The gradient situated in the right ventral quadrant is always present. The caudal bursa shows a pattern of type 1-4. Malvinema frederici possesses a synlophe with 17 ridges and an axis of orientation inclined at 45° from the sagittal axis; M. carolinae possesses a synlophe with 22–24 ridges and an axis of orientation almost merged with the sagittal axis. Both species have a caudal bursa with the right lobe enlarged transversally. Malvinema victoriae possesses a synlophe with 22–24 ridges, an axis of orientation inclined at 45° from the sagittal axis, and a caudal bursa with the right lobe enlarged vertically.

A New Heligmonellid Species (Nematoda) from Oligoryzomys nigripes (Rodentia: Sigmodontinae) in the Atlantic Forest, Brazil

Abstract Stilestrongylus lanfrediae n. sp. is described from the small intestine of Oligoryzomys nigripes (Cricetidae: Sigmodontinae) collected in the Atlantic Forest (Rio de Janeiro State, Teresópolis, Brazil). The new species shows some similarities to Stilestrongylus stilesi, Stilestrongylus freitasi, Stilestrongylus inexpectatus, Stilestrongylus moreli, and Stilestrongylus andalgala, but it can be distinguished from these species by the following combination of characters: 26 ridges in males and 25 in females at the mid-body, asymmetrical caudal bursa with a pattern of type 2-2-1, rays 6 markedly shorter than other lateral rays, rays 8 inserted asymmetrically on dorsal trunk and shorter than other species, and a proportion of spicule length in relation to body length (SpL/BL) of 25–29%. The new species is also distinguished from other species of Stilestrongylus by the asymmetry of the branches of the dorsal ray and by having the longest spicules.

A new molineid (Nematoda: Trichostrongylina) parasite of Dasypus hybridus (Xenarthra: Dasypodidae) from Argentina.

Abstract: Delicata abbai n. sp. collected from the small intestine of the southern long-nosed armadillo, Dasypus hybridus, from Argentina is herein described. This new species is characterized by vulvar opening within second half of body length, female tail conical, ending bluntly with a terminal spine, complex spicules, presence of a bursal membrane supported by 2 small rays, and a synlophe with bilateral symmetry and 26 cuticular ridges. By the morphology of the caudal bursa, caudal end of female, and shape of spicules, the new species resembles Delicata cameroni Travassos, 1935 and Delicata variabilis Travassos, 1935. However, it differs from D. cameroni by having rays 5 and 6 diverging more proximally, rays 8 shorter than the dorsal ray, and spicules with a different shape. Delicata abbai n. sp. is distinguished from D. variabilis mainly by the spicules, which have a different shape and proportion of their constitutive parts. This is the first report of a species of Delicata in Argentina.

Taxonomic revision of the genus Neoheligmonella Durette-Desset, 1971 (Nematoda, Heligmonellidae) parasitic in Muridae mainly from the Ethiopian Region

ABSTRACT The genus Neoheligmonella Durette-Desset, 1971 (Nippostrongylinae) is revised and split into three genera, one of them with two subgenera. The new genera can be discriminated mainly by characters of the synlophe which had been not considered previously at the supraspecific level. These characters include the presence of a careen, the size of the right ridge relative to the left ridge, and the presence of gradients in the ridge size. The genus Neoheligmonella sensu stricto is proposed to include species with a careen, and it is divided into two subgenera: Neoheligmonella (Neoheligmonella) characterized by a right ridge measuring more than 45% of the ventral ridge of the careen, and Neoheligmonella (Duplantierus) n. subgen. with a right ridge measuring less than 45% of the ventral ridge of the careen. Dioufnema n. gen. includes one species with neither a careen nor hypertrophied ridges and having a bursa of type 1-3-1. Taranchonema n. gen. includes species without a careen, with the left ridge and the right ridge hypertrophied, and without a dorsal gradient in ridge size. A dichotomous key to the new genera and subgenera is provided. Five species of unknown synlophe, originally placed in the former genus Neoheligmonella and validated by other characters, are considered as Nippostrongylinae incertae sedis.

Mazzanema n. gen. and Mazzanema fortuita n. comb. for Longistriata fortuita Freitas, Lent, and Almeida, 1937 (Nematoda: Heligmonellidae), a Parasite of the Marsh Rat Holochilus chacarius (Rodentia: Cricetidae) from Northern Argentina

Abstract:  The species described as Longistriata fortuita Freitas, Lent, and Almeida, 1937 is here redescribed from new material collected from the type host, Holochilus chacarius balnearum Thomas, and the type locality, San Martín del Tabacal, Salta, Argentina. Neotypes are designed for the species since the type material deposited by the authors is lost. The original description did not include the synlophe or the female and both are here described. Several characters of the synlophe as the number of ridges (14–19), the ridges continuous and all around body, and the presence of a gradient of size of the ridges allow us to place the species within the Heligmonellidae, Nippostrongylinae. The species possesses a unique combination of characters as the synlophe having a carene together with characters of the caudal bursa as the pattern 1-3-1 and the strong development of the dorsal lobe and ray, which precludes its inclusion in any known genus of Nippostrongylinae. A new genus Mazzanema n. gen. is proposed for it, resulting in the new combination Mazzzanema fortuita n. comb.

A new heligmonellid (Nematoda) from Sylvilagus floridanus (Leporidae) in Costa Rica, with some comments on species of Paraheligmonella Durette-Desset, 1971.

Abstract Paraheligmonella kinsellai n. sp. (Nematoda: Heligmonellidae: Heligmonellinae) is described from the small intestine of a cottontail rabbit Sylvilagus floridanus (Allen, 1890) (Leporidae) from Costa Rica. The new species is similar to P. romerolagi (Gibbons and Kumar, 1980), parasitic in Romerolagus diazi from Mexico and to P. lamothei Digiani, Carreño, and Durette-Desset, 2008, parasitic in Sylvilagus floridanus from Costa Rica, by the characters of the synlophe at mid-body, i.e., 14 cuticular ridges and a single axis of orientation inclined at 30° to the sagittal axis in both sexes. The males of the new species are distinguished from those of P. romerolagi by a caudal bursa that is not bell-shaped, a bursal pattern of type 2–3 with a tendency to 2–2–1, and a genital cone that is not hypertrophied. They are also distinguished from the males of P. lamothei by having the same bursal pattern in both lobes (in P. lamothei the pattern is 2–2–1 on the right lobe and 2–3, with a tendency to 2–2–1, on the left lobe), rays 3 are much longer than rays 2, rays 2 and 3 diverging more proximally, and rays 8 are longer than the dorsal ray. The females of the new species also differ from those of P. lamothei by the shape of the posterior extremity (long and strongly curved vs. short and nearly straight) and by the synlophe at the ovejector level (ridge no. 1′ hypertrophied and remaining ridges reduced vs. ventral ridges hypertrophied and dorso-lateral ridges reduced).