Two new species of Maritrema Nicoll, 1907 (Digenea: Microphallidae) from New Zealand: morphological and molecular characterisation

Abstract

Two new species of the microphallid genus Maritrema (Maritrema) Nicoll, 1907 are described from freshwaters in the South Island of New Zealand. Maritrema deblocki n. sp. occurs as an adult in the mallard Anas platyrhynchos (L.); Maritrema poulini n. sp. is found as sporocysts/cercariae in Potamopyrgus antipodarum (Gray) and as metacercariae in two species of amphipod and two species of isopod. We use morphological and molecular characterisation to distinguish between the two species, and compare them to their four morphologically closest congeners. M. deblocki n. sp. and M. poulini n. sp. are distinguished from each other by the relative sucker size, the positions of the genital pore and ovary, the convergence of the vitelline ribbons, and overall size. With the aid of molecular data, we matched life cycle stages of M. poulini n. sp. and assessed its use of multiple second intermediate hosts. Phylogenetic analyses included sequences for the two new species and the available microphallid sequences for the large ribosomal subunit and the internal transcribed spacer 1 of the ribosomal RNA gene. Closer to each other than to any other species, the sister species together with Maritrema novaezealandense Martorelli, Fredensborg, Mouritsen & Poulin, 2004, Maritrema heardi (Kinsella & Deblock, 1994), Maritrema eroliae Yamaguti, 1939 and Maritrema oocysta (Lebour, 1907) formed a well-supported clade. In addition, we clarify the taxonomic identity of several unidentified Microphallus spp. in the recent ecological literature from New Zealand and propose corrected spellings for a number of Maritrema species epithets.