Browsing by Autor "Davies, Dora"

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A new species of Auriculostoma (Digenea: Allocreadiidae) in South America: life cycle and phylogenetic relationships.
(2022) Liquin, Florencia; Gilardoni, Carmen; Cremonte, Florencia; Saravia, José; Cristóbal, Héctor A; Davies, Dora
Auriculostoma is a genus of digenean (Trematoda) whose adults are parasites of Neotropical freshwater fishes. We describe Auriculostoma ocloya n. sp. using morphological and molecular tools, and we elucidated its life cycle, the first known of a species of this genus. The first intermediate host is the bivalve Pisidium ocloya, the second intermediate host is the amphipod Hyalella sp., and the definite hosts are siluriform fishes. The adult presents a single pair of muscular lobes on either side of the oral sucker with a broad base, stretching from ventrolateral to dorsolateral side, a structure also present in the rest of species of the genus. Nevertheless, the new species differs from all congeners by the combination of several traits, and mainly because on the dorsal side "free" ends of the lobes are absent because they are fused. This is the first study to provide sequence data on larval and adult stages of a species of Auriculostoma. Our phylogenetic analysis demonstrated its basal position among species of the genus. Therefore, integrative morphological, molecular, and life cycle data on other South American species of the genus, would contribute to reveal more patterns in the allocreadiid systematics.
Cucullanus pinnai pinnai and C. pinnai pterodorasi (Nematoda Cucullanidae): what does the integrative taxonomy tell us about these species and subspecies classification?
(2023) Ailán-Choke, Lorena G; Davies, Dora; Malta, Lennon S; Couto, João Victor; Tavares, Luiz Eduardo R; Luque, José L; Pereira, Felipe B
Cucullanus pinnai has been divided in two subspecies (C. pinnai pinnai and C. pinnai pterodorasi) based on the morphology of oesophastome. While C. pinnai pinnai apparently shows low host specificity and broad geographic occurrence, with certain morphological variations, C. pinnai pterodorasi was reported once, parasitizing Pterodoras granulosus. We used an integrative taxonomic approach to evaluate whether or not populations of C. pinnai pinnai from Trychomycterus spegazzinii (Escoipe River, Argentina) and Pimelodus fur (Miranda River, Brazil), and of C. pinnai pterodorasi from Pterodoras granulosus (Miranda River, Brazil) are conspecific. Parasites were observed using light microscopy and genetically characterized based on partial sequences of the 18S and 28S rDNA, ITS1-5.8S-ITS2, and COI mtDNA. Phylogenies were reconstructed and the Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (bPTP), and Automatic Barcode Gap Discovery (ABGD) were used for species delimitation purposes. The present samples formed well-supported monophyletic assemblages, corroborating in part the results of morphological analyses; however, they grouped according to geographic origin. Species delimitation suggested conspecificity of C. pinnai pinnai with C. pinnai pterodorasi from Brazil; consequently, the morphology of oesophastome may be an intraspecific variation. Results also indicated that C. pinnai may represent a species complex as samples from Argentina were suggestive of an independent specific entity. However, definitive affirmations are premature, since there is no autapomorphy for separating C. pinnai from Brazil and Argentina and sampling was limited to three host species from two river basins. The phylogenetic reconstructions also confirmed the artificiality of some genera within Cucullanidae.
Further study on Procamallanus (Spirocamallanus) pintoi (Kohn et Fernandes, 1988) (Nematoda: Camallanidae) in Corydoras paleatus and Corydoras micracanthus (Siluriformes: Callichthyidae) from Salta, Argentina, with a key to congeneric species from Neotropical Realm.
(2018) Ailán-Choke, Lorena G; Ramallo, Geraldine; Davies, Dora
This study describes the morphology of Procamallanus (Spirocamallanus) pintoi (Kohn et Fernandes, 1988), isolated from the intestine of Corydoras micracanthus Regan, 1912 and C. paleatus (Jenyns, 1842) (both Callichthyidae, Siluriformes) from Bermejo and Juramento River basins, respectively, province of Salta, Argentina. This is the first record of P. (S.) pintoi in C. micracanthus from Northwestern Argentina. The light and scanning electron microscopy observations of P. (S.) pintoi, revealed a few previously unreported morphological details of the cephalic region, vulva and caudal region of males. In addition, morphometric variability was observed in, mainly body size, glandular oesophagus length and position of the vulva between present specimens and those described in previous studies. A key to the species of Procamallanus (Spirocamallanus) from the Neotropical Realm is proposed.
Histopathological study of Corydoras micracanthus (Siluriformes: Callichthyidae) parasitized by the nematode Procamallanus (Spirocamallanus) pintoi (Camallanidae) from Lesser River, northwestern Argentina, South America.
(2019) Ailán-Choke, Lorena G.; Sánchez, Roberto; Cremonte, Florencia; Ramallo, Geraldine; Davies, Dora
The nematode parasites can cause mechanical injuries such as irritation or atrophy of tissue and occlusions of the digestive tract, blood vessels or other ducts in their hosts. Some species belonging to the family Camallanidae have been the focus of histopathological studies because they lacerate the host´s intestinal wall with their buccal capsule. In this study, we describe the histopathological effects produced by Procamallanus (Spirocamallanus) pintoi in the small fish Corydoras micracanthus from Lesser River, in the northwest of Argentina, South America. The samples were processed with routine histology techniques. At light microscopy, specimens of P. (S.) pintoi were observed occupying the lumen of the gut. The histopathological sections revealed damage to the host intestine with the total destruction of the mucosa and submucosa, observed mainly in the region which is surrounding the buccal capsule of parasites. Moreover, an inflammatory reaction was observed with lymphatic accumulations in the affected tissue. This kind of degenerative and necrotic changes in the mucosa could affect negatively the absorption function of the host intestine, which may have adverse effects of the health status of fish. The present study provides the firs data about the histopathological effects of P. (S.) pintoi in C. micracanthus.
Morphological and ITS2 Molecular Characterization of Ribeiroia Cercariae (Digenea: Psilostomidae) from Biomphalaria spp. (Gastropoda: Planorbidae) in Northern Argentina.
(2015) Davies, Dora; Davies, Carolina; Lauthier, Juan José; Hamann, Monika; Ostrowski de Núñez, Margarita
Species of Ribeiroia use planorbid snails as intermediate host. Since there is little information about these digenean parasites in South America, we aimed to assess whether Ribeiroia cercariae from 3 north Argentina locations belonged to the same species and differed from Ribeiroia cercariae described elsewhere. Specimens were obtained from Biomphalaria tenagophila and Biomphalaria orbignyi (Salta Province), and Biomphalaria occidentalis (Corrientes Province). Morphological traits of cercariae were analyzed, as well as their sequence of the ribosomal internal transcribed spacer 2 (ITS2). The ITS2 region consisted of 426 nucleotides identical in all samples, suggesting that all specimens belong to the same species in spite of their morphological differences and first intermediate host species. Comparison of the ITS2 region with GenBank database records showed that specimens from Argentina were different from Ribeiroia ondatrae (0.9% divergence), Ribeiroia marini (0.7% divergence), and Cercaria lileta (0.2% divergence). In summary, morphological, ecological, and ITS2 molecular data suggest that specimens from Argentina belong to a different species.
New species of Raphidascaris (Sprentascaris) (Nematoda: Anisakidae) in Rineloricaria steinbachi (Actinopterygii: Loricariidae) from Northwest Argentina.
(2017) Ailán-Choke, Lorena Gisela; Ramallo, Geraldine; Davies, Dora
During a parasitological survey, we reported specimens of a new species of Raphidascaris (Sprentascaris) in Rineloricaria steinbachi from La Caldera River, province of Salta, Northwest Argentina. The new species, R. (S.) saltaensis sp. nov., is characterized by possessing 16 pairs of preanal papillae, lips with lateral protrusions and membranous elevations, and mature eggs rough-shelled with striations. This is the sixth species of the genus described in the Neotropical Region, and the second from Argentina. Rineloricaria steinbachi is reported as host of this nematode genus for the first time. A key to the species of Raphidascaris (Sprentascaris) in the Neotropical realm is provided. Also, zoogeographical and host information of the species, belonging to the subgenus Sprentascaris, is summarized.
The life cycle of Australapatemon magnacetabulum (Digenea: Strigeidae) from Northwestern Argentina.
(2012) Davies, Dora; de Núñez, Margarita Ostrowski
The life cycle of Australapatemon magnacetabulum Dubois, 1988 was resolved experimentally. Planorbid snails Biomphalaria tenagophila (d'Orbigny, 1835) collected in a small pond at the confluence of the San Lorenzo and Arias Rivers, near Salta City, Province of Salta, Argentina, were found to be shedding furcocercous cercariae possessing 4 pairs of penetration glands, 1 pair of unpigmented eyespots, 6 pairs of flame cells in the body, and 1 pair in the tail stem. Metacercariae were found encysted in naturally, and experimentally, exposed leeches Helobdella adiastola Ringuelet, 1972, Helobdella triserialis (Blanchard, 1849), Haementeria eichhorniae Ringuelet 1978, and Haementeria sp., and within their sporocysts in naturally infected planorbid intermediate hosts. Sexually mature adults were recovered from domestic chicks and a duck 8-28 days postexposure by metacercariae from leeches. The identification of the species was based upon the characteristic large ventral sucker and a genital cone, crossed by a hermaphroditic duct with internal folds, occupying approximately a 1/4 to 1/5 of the hindbody.
The life cycle of Magnivitellinum saltaensis n. sp. (Digenea: Alloglossidiidae) in Salta Province, Argentina.
(2021) Davies, Dora; Liquin, Florencia; Lauthier, Juan José; Párraga, Regina; Saravia, José; Davies, Carolina; Ostrowski de Núñez, Margarita
We describe the alloglossiid trematode Magnivitellinum saltaensis n. sp., a parasite of the characiform fish Psalidodon endy, and its life cycle from Salta, northwest of Argentina. This is the first life cycle described for a species belonging to the genus Magnivitellinum. Cercariae emerged naturally from Biomphalaria tenagophila snails and infected experimentally exposed larvae of Diptera and Ephemeroptera as second intermediate hosts. These larvae in turn were exposed to commercially raised fish, and adults were recovered from characiform albino fish Gymnocorymbus ternetzi. Molecular analysis of natural and experimental adults showed the same genetic sequence for the partial region of 28S rDNA, thus confirming conspecificity. Comparison of these sequences with those published for M. simplex from Mexico showed 1.45% divergence, indicating that the specimens found in Salta belong to a different species, the third described of Magnivitellinum, in agreement with morphological data, geographical location, and host species composition. The new species is distinguished by its small body, vitelline follicles extending from the mid-level of the ventral sucker, Y-shaped excretory vesicle, and presence of papillae around the mouth.