Survey of trematodes in intertidal snails from Patagonia, Argentina: new larval forms and diversity assessment

Abstract

Larval trematodes are the main parasites of snails, and they play a crucial role because they usually castrate their snail hosts and can thus alter their population and community dynamics. This study involved a survey of seven gastropod species (Crepipatella dilatata, Fissurella radiosa, Nacella magellanica, Pareuthria fuscata, Siphonaria lessonii, S. lateralis and Trophon geversianus) parasitized by 12 trematode species (one hemiurid, one gymnophallid, two lepocreadiids, two microphallids, one notocotylid, two renicolids, one philophtalmid, one schistosomatid and one zoogonid) from southern Patagonia (47°S, 65°W), Argentina. Only F. radiosa was free of parasites. The study included the description of five new larvae, based on morphological and molecular information, and a comparison of the parasite diversity with that of a northern locality (42°S, 64°W), characterized by a lower mollusc diversity. Species richness and diversity of parasites were higher in the southern site. This suggests a correlation between the level of parasitism and the diversity of molluscs (first intermediate hosts), which is higher at the high-latitude site and seems to attract shorebirds, which disperse the digenean eggs and facilitate the completion of their life cycles. These results support the notion that parasitism is influenced by large-scale factors such as biogeographical patterns, and small-scale factors such as diversity or abundance of intermediate and definitive hosts.

Cryptic speciation of the zoogonid digenean Diphterostomum flavum n. sp. demonstrated by morphological and molecular data

“…Specifically, most trematodes lack hard parts, especially in their terminal genitalia, which can be of great assistance in species differentiation [61]. Larval stages can be difficult to distinguish morphologically between species [38,45]; however, some diagnostic characters of cercariae can be useful including stylet shape, size of suckers, shape of excretory vesicle, and number of penetration glands (e.g., [6,31,32]). For D. brusinae, Palombi [54] described two groups of penetration glands in Italian cercariae, Pina et al [60] described three pairs of glands in Portuguese cercariae, and at least nine pairs of glands separated into three groups are recorded in this study in cercariae from the Southwestern Atlantic Ocean.…”

“…For example, two pulmonate limpets, Siphonaria lessonii Blainville and S. lateralis Gould (Siphonariidae), share a parasite species, the microphallid Maritrema madrynense Diaz & Cremonte, 2010; these two limpets are ecologically and genetically very similar and can be found together in the same intertidal region from South Patagonia, Argentina [20]. At the same site, Crepipatella dilatata (Lamarck) (Calyptraeidae) inhabits the lower intertidal and subtidal zone and is infected by larvae of a microphallid species very similar to M. madrynense but possessing a different stylet and number of penetration glands [31,32]. Here it is evident that the specificity for the first intermediate host is related to parasite-host co-evolution and morphological differences between larvae.…”

“…Uterine loops filled with eggs from ventral sucker level to posterior end, never exceed ventral sucker. Eggs elliptical, large, embryonated, 31(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41) long by 14(11)(12)(13)(14)(15)(16)(17)(18)(19) wide, membranous capsule. Excretory vesicle spherical, 70(68)(69)(70)(71)(72) long by 74(74)(75)(76) width.…”

A morphological, molecular and life cycle study of the capybara parasite Hippocrepis hippocrepis (Trematoda: Notocotylidae)

“…The use of molecular tools becomes promising for the link between developmental stages of notocotylid trematodes, as verified for some species in Europe and Asia [23–25]. However, the molecular approach depends on the existence of available sequences for the respective adult parasites, which are non-existent for most species of Notocotylidae, making specific or generic identification by the molecular approach impossible, as shown by some authors [21, 53, 54]. In fact, the sequences obtained in the present study for H .…”

The influence of physicochemical environment on the distribution and abundance of mangrove gastropods in Ngurah Rai Forest Park Bali, Indonesia

“…The results of the dominance value show the richness of species communities and the balance of a total of individuals of each species (Levin et al 2015;Gilardoni et al 2019). The results of the dominance index were in the range of 0.12-0.17 ( Figure 3).…”