Paramonostomum deseado n. sp. (Digenea: Notocotylidae) parasitizing the South American Black Oystercatcher and their atypical life cycle from the Patagonian coast

BAGNATO ESTEFANÍA; GILARDONI CARMEN; LAUTHIER JUAN JOSE; CREMONTE FLORENCIA

PARASITOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2022

0031-1820

Via morphological and molecular analysis we describe a new species of notocotylid, Paramonostomum deseado n. sp., parasitizing Haematopus ater from Argentina and we contribute to elucidate its life cycle. Within this genus, four groups can be morphologically distinguished according to body shape: "Oval", "Pyriform", "Elongate", "Overlong". The new species belongs to “Elongate group”, which presents a wide variation in body length (597 to 4,500 µm). The new species, P. caeci from Australia, P. actitidis from Caribbean and P. alveoelongatum from Russia share the smallest range of body size in this group (< 1,130 µm). The new species more closely resembles to P. actitidis but differs from it by cirrus-sac length, which is shorter in the new species (97-146 vs. 280-430 µm in P. actitidis), and egg size which is larger in the new species (25-33 vs. 18-20 µm in P. actitidis). Paramonostomum deseado n. sp. uses the limpet Nacella magellanica as both first and second intermediate hosts in which metacercariae encyst inside the redia. This is the first abbreviated cycledescribed for notocotylid species. Ribosomal RNA sequences provided for adults (ITS1, ITS2, and 28S) and metacercariae inside the rediae (ITS1) support the species identification and the correspondence among stages. Phylogenetic analysis based on 28S placed P. deseadon. sp. close to other Notocotylus spp. and Paramonostomum anatis. Molecular results demonstrate that the hosts involved in the life cycles and the habitat more than morphological differences are determining the phylogenetic relationships in members of Notocotylidae.