Carmen Mariangel Gilardoni

A survey of larval digeneans in the commonest intertidal snails from Northern Patagonian coast, Argentina

Over a two-years period, a survey was carried out in order to increase the knowledge of digeneans parasitising the commonest intertidal gastropods on the Patagonian coast, Southwestern Atlantic Ocean. A total of 4,725 gastropods were examined. Six species of digenean parasitising four snail species were found; four of them were registered for first time: Maritrema sp. 1 (Microphallidae) in Crepidula dilatata (Calyptraeidae), Parorchis sp. (Philophtalmidae) and sporocyst of Renicolidae in Trophon geversianus (Muricidae), and Diphterostomum sp. (Zoogonidae) in Buccinanops globulosus (Nassariidae). Two other species were found in Siphonaria lessoni (Siphonariidae): Maritrema sp. 2 and Hemiuridae. One snail species, Tegula patagonica (Trochidae) was not parasitised. These gastropods act as first intermediate host, and C. dilatata, S. lessoni and B. globulosus also frequently host metacercariae within the sporocyst. Overall prevalences varied from 0.16% of Diphterostomum in the intertidal population of B. globulosus to 33.45% of Maritrema sp. 1 in C. dilatata.

Description of Maritrema formicae sp. nov. (Digenea, Microphallidae) parasitic in the kelp gull, Larus dominicanus, from the Patagonian coast, Argentina

Maritrema formicae sp. nov. is described from the Patagonian coast, Argentina, based on adults obtained from the kelp gull, Larus dominicanus. The new species fits with the “eroliae complex” and can be distinguished from other related species mainly in shape and size of body, shape, size, and pattern of distribution of cirrus spines, uterus extension, number and size of eggs, vitellarium in a complete ring in all specimens, and its Neotropical distribution. The new species is sympatric with another species of the genus, Maritrema madrynense, which was recorded in the same host and locality.

Monorchiid and aporocotylid cercariae (Digenea) parasitising the purple clam Amiantis purpurata (Bivalvia, Veneridae) from the Southwestern Atlantic coast

Two cercariae, one of them ocellate and with well developed tail (Monorchiidae) and another apharyngeate brevifurcocercous (Aporocotylidae), parasite of Amiantis purpurata (Lamarck, 1818) (Bivalvia, Veneridae) from the Patagonian coast on the Southwestern Atlantic Ocean, are described. These reports comprise the second monorchiid intramolluscan infection reported for the Southern Hemisphere and first intramolluscan aporocotylid for the Southern Hemisphere. In addition, this constitutes the first report of aporocotylid intramolluscan stages (parthenita) occupying only the haemocoel of the gills of a marine molluscan host rather than the digestive gland and gonad, the usual site of infection.

A histopathological survey of the razor clam Ensis macha (Pharidae) along the Patagonian Argentina coast

This is the first study performed to determine the health status of the razor clam, Ensis macha, including six different populations along Argentina Patagonian coast and one of Chile. The parasites and pathologies affecting E. macha were analyzed and their prevalence and mean intensity values were calculated. To establish which factors affect the presence and intensity of infection, Generalized Linear Models (GLMs) were applied. Basophilic inclusions, ciliates, coccidians protozoans and turbellarians were found. We report an Aporocotylidae digenean and hemocyte infiltrations. None of the parasites is OIE (World Organisation for Animal Health) notifiable, and none seemed to be pathogenic, with the exception of the digenean. The prevalence of the parasites was affected mainly by environmental factors (such as site of sampling and season) instead of intrinsic conditions of the clam (such as size, condition index, sex and gonadal stage). On the other hand, the maximum intensity of parasites was not only related with cold seasons but also with the partially spawned gonadal stage of E. macha. During this stage, the clams would need to store energy for the next gametogenesis cycle, might be more susceptible to infection by the parasites.

A new species of gymnophallid (Digenea) and an amended diagnosis of the genus Gymnophalloides fujita, 1925.

Abstract:  Morphological and molecular evidence suggest that specimens formerly described as Lacunovermis sp. from Nacella (Patinigera) spp. (Patellogastropoda: Patellidae) belong to a new species of Gymnophalloides Fujita, 1925. Based on the new information, they are identified as Gymnophalloides nacellae n. sp. The new species differs from Gymnophalloides tokiensis, Gymnophalloides seoi, and Gymnophalloides heardi mainly through the presence of a group of papillae located on the ventral surface between oral and ventral suckers. A detailed morphological study revealed the lack of pars prostatica, a character previously reported in G. seoi, which is why it was formerly placed in the Gymnophallinae. Molecular information proved that G. nacellae is close to G. seoi, being nestled together with Parvatrema representatives. This molecular information, along with the absence of pars prostatica, allows these 2 genera to be placed in Parvatrematinae. An amended diagnosis of Gymnophalloides is provided. Histological sections of mantle epithelium of the limpet show metacercariae attached by their oral and ventral suckers in a similar manner to G. seoi in its host, the oyster Crassostrea gigas. Tissue reaction includes cells of outer mantle epithelium being stretched by sucker attachment, hemocyte infiltration of connective tissue between mantle epitheliums, and abnormal calcareous deposition on the inner surface of the shell.

Revision of the family Gymnophallidae Odhner, 1905 (Digenea) based on morphological and molecular data

This paper reviews the family Gymnophallidae, recognizing as valid seven genera; four within the subfamily Gymnophallinae: Gymnophallus Odhner, 1900 (syn. Meiogymnophallus Ching, 1965), Paragymnophallus Ching, 1973, Pseudogymnophallus Hoberg, 1981, and Bartolius Cremonte, 2001, and three in the Parvatrematinae: Parvatrema Cable, 1953, Lacunovermis Ching, 1965, and Gymnophalloides Fujita, 1925. Specimens representing one species of each available genus were chosen from those well-described and non controversial species, for which strong morphological information was available, and used for molecular studies (ITS1-5.8S-ITS2-28S rDNA strands were sequenced). The presence or absence of a pars prostatica differentiates between the 2 subfamilies, Gymnophallinae and Parvatrematinae. The characters used to differentiate genera are: location of the ovary (pre-, post- or inter-testicular), size and location of the genital pore (inconspicuous and located at the anterior margin of the ventral sucker, or conspicuous and located at some distance from the anterior margin of ventral sucker), presence of caecal pockets, and presence or absence of ventral pit (a muscular structure which can be either well-developed, similar in size and musculature to the ventral sucker, or be poorly developed). The characters previously used to distinguish among genera that actually should be considered to separate species include: shape of tegument spines (broad, sharp or serrated), presence of lateral projections on the oral sucker (also called papillae or lips), shape of the seminal vesicle (unipartite or bipartite), shape of the prostatic duct (elongate or oval), presence of papillae on the genital pore, shape of the genital atrium (tubular, wide, oval), shape of the vitellaria (follicular in a variable degree, paired or single), shape of the excretory vesicle (V or Y), and extension of uterus (restricted to forebody, at hindbody or extending in both). Additionally, some of these characters may vary with the age of worm. The morphological and molecular information obtained in this study provided strong support for recognizing seven valid genera in the family Gymnophallidae.

A checklist of marine larval trematodes (Digenea) in molluscs from Argentina, Southwestern Atlantic coast

A checklist of cercariae parasitizing marine molluscs from Patagonian coast, Argentina, based on literature sources and new records here presented. In total, cercariae of 31 species of marine digeneans, including 11 new records here presented, are known to infect 20 species of molluscs (14 in nine gastropods species; 17 in 11 bivalve species). These records include two species of Aporocotylidae, four Bucephalidae, one Fellodistomidae, five Gymnophallidae, one Hemiuroidea, four Lepocreadiidae, two Microphallidae, five Monorchiidae, one Notocotylidae, one Philophthalmidae, two Renicolidae, one Schistosomatidae and two Zoogonidae. For each digenean species, their hosts, habitat type, localities, infection site, prevalence, life cycle advances, and access numbers in helminthological collections and GenBank, when available, are detailed. Regarding the life cycles, eight were completely elucidated and four were partially elucidated. Moreover, there are molecular data for 15 species. The data here presented constitutes an advance in the parasites biodiversity knowledge and their life cycles.

Atypical lesions and infection sites of larval trematodes in marine gastropods from Argentina

This study documents the lesions caused by 9 digenean larvae parasitizing 6 marine gastropod species from Patagonia, Argentina. Most digeneans produce a lesion where the parthenitae replace the gonadal tissues and also occupy part of the digestive gland. Three atypical lesions and tropism were observed in (1) Trophon geversianus (Muricidae) infected by Renicolidae gen. et sp. 1, where the sporocysts occur inside the gonad acini which retain their general structure due to the persistence of the acinus wall, (2) Nacella magellanica (Nacellidae) infected by Renicolidae gen. et sp. 2, where the gonad is not affected and the sporocysts are located only among the digestive gland tubules, and (3) Siphonaria lessonii (Siphonariidae) infected by Schistosomatidae gen. et sp., where fully developed cercariae occur inside the digestive tubules. At high infection intensities or in double infections, larvae can invade other organs (mantle, foot or gill) and, on occasion, may elicit hemocytic encapsulation.

Larval digenean preferences in two sympatric snail species at differing tidal levels off the Atlantic coast of Patagonia

Larval stages of the trematodes Maritrema madrynense and Hemiuroidea fam. gen. et sp. differentially parasitized Siphonaria lessonii and S. lateralis, two sympatric pulmonate snail species on the rocky intertidal shore at Puerto Deseado, south-western Atlantic coast of Patagonia, Argentina. Snail specimens were collected at two sampling sites with contrasting physical-chemical characteristics. One site, in the upper intertidal, was exposed to sewage from fish-processing plants, greater hydrodynamic forcing and desiccation, a wider temperature range, longer exposure to ultraviolet radiation and higher abundance of birds. The second site, in the lower intertidal, was generally characterized by less stressful environmental conditions. At both sites, S. lateralis showed a markedly higher density than S. lessonii (55.13 vs. 5.87 snails/m2, respectively). Despite this, the prevalence of both digeneans was higher in S. lessonii (17.37% and 3.52% for M. madrynense and Hemiuroidea, respectively) than in S. lateralis (0.09% and 0% for M. madrynense and Hemiuroidea, respectively). This study demonstrates high parasite specificity for the host. Low densities of S. lessonii are attributed to castration of parasitized hosts and reduction of their physiological condition. The prevalence and intensity of infection of both digenean parasites were higher at the more stressful, upper intertidal site, thus suggesting that a higher abundance of birds and exposure to sewage pollution may promote the transmission of trematodes.

Stomach nematodes of three sympatric species of anatid birds off the coast of Patagonia.

The present study focuses on the nematode community in the stomachs of three sympatric anatid bird species from the Central Patagonian coast, Argentina. The bird species include the Chubut steamer duck, Tachyeres leucocephalus, the crested duck, Lophonetta specularioides, and the black-necked swan, Cygnus melancoryphus. Up to 138 nematodes representing five species were recovered from 10 of the 13 ducks examined, with an overall prevalence of 77% and a mean intensity of 13.8. Nematodes isolated from the gizzard were Streptocara formosensis and Sciadiocara legendrei (Acuariidae) in T. leucocephalus, and Epomidiostomum vogelsangi (Amidostomatidae) in C. melancoryphus, whereas Echinuria uncinata (Acuariidae) and Tetrameres (Petrowimeres) fissispina (Tetrameriidae) were found in the proventiculus of L. specularioides. In particular, S. legendrei was registered for the first time in South America and T. leucocephalus, whereas T. fissispina represents a new record in Argentina and L. specularioides. Moreover, E. vogelsangi and E. uncinata were isolated in Patagonia for the first time. The birds studied herein are sympatric in their distribution, and two of them are syntopic breeders; however, they were infected with different parasite species. This situation could be partially due to their diet or their seasonal movements, or a combination of both. Despite the low number of hosts examined, this work enhances our knowledge about parasites from a frequently occurring group of birds on the Patagonian coast, a subject that has not been studied extensively in South America.