A new species of Maritrema (Trematoda: Microphallidae) parasitizing the Baird's sandpiper Calidris bairdii, and comments about diversity of Microphallidae in two Nearctic shorebirds at Patagonian sites in Argentina

Parasitological survey of coastal birds from the Magellanic coast, Southwestern Atlantic Ocean

Ecto and endoparasites of four species of coastal birds, Haematopus ater, Larus dominicanus, Leucophaeus scoresbii (Charadriiformes), and Lophonetta specularioides (Anseriformes), are reported from Puerto Deseado on the Patagonian coast, Argentina. Only H. ater was infested with lice (Phthiraptera), belonging to 2 species (Ischnocera, Amblycera). A total of 19 helminth species were found parasitizing the coastal birds studied: 4 cestodes (1 Tetrabothriidae, 3 Cyclophyllidea); 11 trematodes (2 Gymnophallidae, 3 Microphallidae, 2 Notocotylidae, 1 Philophthalmidae, 2 Renicolidae, 1 Schistosomatidae); 3 nematodes (1 Anisakidae, 2 Acuariidae); and 1 acanthocephalan (Polymorphidae). Although some isolated records have been previously reported for these birds, the present work provides a parasitofauna study for H. ater, L. scoresbii, and L. specularioides for the first time. Endoparasites reflected the feeding habits of the birds; the parasite assemblage of L. dominicanus was the richest, indicating their wide prey spectrum and the diversity of the habitats frequented. A great species richness of trematodes, whose life cycles are partially known, suggests that L. specularioides feeds upon crustaceans and small bivalves. The blackish oystercatcher H. ater preys upon the limpet Nacella magellanica which hosts two larval trematodes corresponding to the adults found parasitizing it.

First molecular identification of the trematode Maritrema bonaerense Etchegoin & Martorelli, 1997 (Plagiorchiida, Microphallidae) from its intermediate hosts, the gastropod Heleobia australis (d’Orbigny, 1835) (Littorinimorpha, Cochliopidae) and the crab Neohelice granulata (Dana, 1851) (Decapoda, Varunidae) in Argentina

The genus Maritrema Nicoll, 1907 (Platyhelminthes, Trematoda, Plagiorchiida, Microphallidae) comprises cosmopolitan species that predominantly parasitize birds. Although approximately 65 species have been described worldwide, including 6 for Argentina, molecular data referring to Maritrema species are still scarce worldwide, especially in South America. Unfortunately, this lack of references for nucleotide sequences is an obstacle to understanding the taxonomy and life cycles of trematodes, and impedes advancing our studies on the phylogeny and geographical distribution of these parasites. For that reason, we performed the molecular study of developmental stages of Maritrema bonaerense: cercariae (collected from the snail first intermediate host Heleobia australis, inhabiting Mar Chiquita lagoon) and metacercariae (collected from the crab second intermediate host Neohelice granulata, inhabiting Mar Chiquita lagoon and San Antonio Oeste, Argentina). The accordance between the ITS2 sequence of M. bonaerense cercaria from the snail H. australis and the sequences of metacercariae from the crab N. granulata was 100%, supporting previous findings of the life cycle of M. bonaerense based on morphological data. All Maritrema species are included in a monophyletic and well-supported clade. Maritrema bonaerense grouped more closely with Maritrema gratiosum. These findings contribute to the knowledge of digeneans in coastal marine ecosystems.

Morphological and molecular characterization of Maritrema kostadinovae n. sp. (Digenea: Microphallidae) from the yellow-crowned night heron Nyctanassa violacea (Aves: Ardeidae) in Mexico

A new species of microphallid trematode was collected from the intestine of the yellow-crowned night heron Nyctanassa violacea (L.) (Pelecaniformes: Ardeidae) from Veracruz, Mexico. Maritrema kostadinovae n. sp. differs distinctly from other members of Maritrema Nicoll, 1907 from the Americas by its smaller body size (262-435 × 242-363 μm), the extension of caeca (reaching to anterior level of ventral sucker), the size and shape of the cirrus (short, tubular and unarmed) and metraterm (simple and thin-walled), the position of the genital pore (sinistrolateral to ventral sucker) and the arrangement of the vitellaria (horseshoe-shaped with posteriorly directed opening). Maximum likelihood and Bayesian inference analyses, based on partial 28S rDNA sequences, depicted M. kostadinovae n. sp. within the genus Maritrema with strong support. The new species is in a sister position to other available members of Maritrema, except for M. subdolum Jägerskiöld, 1909 that branches as the early divergent species in the Maritrema clade. The new species is the third species of Maritrema described from birds in Mexico. Comparative morphometric data for Maritrema taxa from birds and mammals from the Americas is provided.