Neopsilotrema n. g. (Digenea: Psilostomidae) and three new species from ducks (Anseriformes: Anatidae) in North America and Europe

SUPPLEMENTAL DESCRIPTION OF CABALLEROTREMA ANNULATUM (DIESING, 1850) OSTROWSKI DE NÚÑEZ AND SATTMANN, 2002 (DIGENEA: CABALLEROTREMATIDAE) FROM A NEW HOST (ELECTROPHORUS CF. VARII) AND LOCALITY (AMAZON RIVER, COLOMBIA) WITH PHYLOGENETIC ANALYSIS AND EMENDED GENERIC DIAGNOSIS

Herein, we provide a supplemental description of Caballerotrema annulatum (Diesing, 1850) Ostrowski de Núñez and Sattmann, 2002 (Digenea: Caballerotrematidae Tkach, Kudlai, and Kostadinova, 2016) based on specimens collected from the intestine of an electric eel, Electrophorus cf. varii (Gymnotiformes: Gymnotidae) captured in the Amazon River (Colombia). This caballerotrematid can be differentiated from its congeners by the following combination of morphological features: body surface spines forming contiguous transverse rows, concentric (wrapping dorso-ventrally around body), distributing into posterior body half (vs. restricted to anterior body half in Caballerotrema brasiliensePrudhoe, 1960; indeterminate for Caballerotrema aruanenseThatcher, 1980 and Caballerotrema piscicola [Stunkard, 1960] Kostadinova and Gibson, 2001); head collar lacking projections (vs. having them in C. brasiliense, C. aruanense, and C. piscicola), narrow (head collar more narrow than maximum body width vs. the head collar being obviously wider than the body in C. brasiliense, C. aruanense, and C. piscicola); corner spines clustered (vs. corner spines distributing as 2 separated pairs in C. brasiliense, C. aruanense, and C. piscicola); pharynx approximately at level of the corner spines (vs. pharynx far anterior to corner spines in C. brasiliense, C. aruanense, and C. piscicola); and testes ovoid and nonoverlapping (C. aruanense; vs. sinuous and overlapping in C. brasiliense and C. piscicola). Based on our results, we revise the diagnosis of CaballerotremaPrudhoe, 1960 to include features associated with the shape and distribution of body surface spines, orientation and position of head collar spines, cirrus sac, seminal vesicle, oviduct, Laurer's canal, oötype, vitellarium, and transverse vitelline ducts. We performed Bayesian inference analyses using the partial large subunit ribosomal (28S) DNA gene. Our 28S sequence of C. annulatum was recovered sister to that of Caballerotrema sp. (which is the only other caballerotrematid sequence available in GenBank) from an arapaima, Arapaima gigas (Schinz, 1822) (Osteoglossiformes: Arapaimidae) in the Peruvian Amazon. Our sequence of C. annulatum comprises the only caballerotrematid sequenced tethered to a morphological description and a voucher specimen in a lending museum. The present study is a new host record and new locality record for C. annulatum. The phylogeny comprises the most resolved and taxon-rich evolutionary hypothesis for Echinostomatoidea published to date.

New species of Psilotrema and Sphaeridiotrema (Psilostomidae Odhner, 1913) in the east Asian region: Morphology of developmental stages and genetic data

Morphological and genetic data have been obtained for five new East Asian species of the Psilostomatidae. The life cycle of Psilotrema limosum n. sp. was carried out using Parafossarulus manchouricus as the first intermediate host. Compared with the East Asian species of the genus, these worms differ in morphometric characters in both the cercarial and adult stages. Its validity was also confirmed by the 28S rRNA gene data. Data on the life cycle and morphology of developmental stages of Sphaeridiotrema ussuriensis n. sp. and Sphaeridiotrema aziaticus n. sp. were also obtained. Cercariae of these species are found in Parafossarulus and Boreoelona snails, respectively. Sphaeridiotrema ussuriensis n. sp., like Sphaeridiotrema monorchis in China, has one testis, while S. aziaticus n. sp. has two testes. In addition, S. monorchis from Vietnam and Sphaeridiotrema spinoacetabulum from the Russian southern Far East are justified as belonging to the new species named Sphaeridiotrema vietnamensis n. sp. and Sphaeridiotrema pyriforme n. sp., respectively. This proposition is based on the morphology of developmental stages, the list of the first intermediate hosts and the 28S rRNA gene data. Analysis of the phylogenetic relationships within Psilostomatidae revealed three clusters, including taxa with different life cycles strategies. Sphaeridiotrema was also divided into two groups, which combine species according to their intermediate hosts and geographical localisation.

A paradigm for the recognition of cryptic trematode species in tropical Indo-west Pacific fishes: the problematic genus Preptetos (Trematoda: Lepocreadiidae)

Molecular data have transformed approaches to trematode taxonomy by providing objective evidence for the delineation of species. However, although the data are objective, the interpretation of these data regarding species boundaries is subjective, especially when different markers conflict. Conserved markers can lead to an underestimation of richness and those used for finer species delineation have the capacity to inflate species recognition, perhaps unrealistically. Here we examine molecular and morphological evidence for species recognition in an especially confusing system, the lepocreadiid genus Preptetos Pritchard, 1960 in acanthuriform fishes of the tropical Indo-west Pacific. We consider species boundaries within this genus based on combined data (ITS2 and 28S rDNA; cox1 mtDNA and morphometrics) for substantial new collections. Delineation of species using only morphological data suggest fewer species than analysis of the sequence data; the latter suggests the presence of potential cryptic species and analysis of different markers suggests the presence of differing numbers of species. We conclude that an integrative interpretation creates the most satisfying taxonomic hypothesis. In the light of the new data, we have chosen and propose a model of trematode species recognition that demands reciprocal monophyly in the most discriminating available molecular marker plus distinction in morphology or host distribution. By invoking these criteria, we distinguish eight species in our new tropical Indo-west Pacific collections. Six of these are new (Preptetos allocaballeroi n. sp., Preptetos paracaballeroi n. sp., Preptetos pearsoni n. sp., Preptetos prudhoei n. sp., Preptetos quandamooka n. sp. and Preptetos zebravaranus n. sp.) and we continue to recognise Preptetos cannoni Barker, Bray & Cribb, 1993 and Preptetos laguncula Bray and Cribb, 1996. Notably; two of the new species, P. allocaballeroi n. sp. and P. paracaballeroi n. sp., are morphologically cryptic relative to each other. Our criteria lead us to recognise, as species, populations with unvarying morphology and similar host relationships but which may have a complex population structure over their range. In our view, this paradigm has the capacity to render tractable the interpretation of the species status of the huge trematode fauna of the tropical Indo-west Pacific.

DESCRIPTION AND PHYLOGENETIC AFFINITIES OF A NEW SPECIES OF NEOPSILOTREMA (DIGENEA: PSILOSTOMIDAE) FROM LESSER SCAUP, AYTHYA AFFINIS (ANSERIFORMES: ANATIDAE)

Neopsilotrema is a small genus of psilostomid digeneans parasitic in the intestine of birds in the Palearctic and Nearctic. At present, the genus includes 4 species: Neopsilotrema lisitsynae from the Palearctic and Neopsilotrema affine, Neopsilotrema lakotae, and Neopsilotrema marilae from the Nearctic. Herein, we describe a new species, Neopsilotrema itascae n. sp., from lesser scaup Aythya affinis collected in Minnesota. The species can be distinguished from congeners on the basis of the ventral sucker:oral sucker width ratio, body width:length ratio, and cirrus sac size, along with other characters. We generated new 28S ribosomal deoxyribonucleic acid (DNA) and NADH dehydrogenase (ND1) mitochondrial DNA sequence data of a variety of psilostomids from the Palearctic and Nearctic along with sequences of the ribosomal internal transcribed spacer (ITS) region (ITS1 + 5.8S + ITS2) from 3 Neopsilotrema species. The molecular phylogenetic affinities of a variety of psilostomid taxa were studied using 28S sequence data. The 28S sequences of psilostomids demonstrated 1-7.9% intergeneric divergence, whereas the sequences of ND1 had 17.7-34.1% intergeneric divergence. The interspecific divergence among members of Neopsilotrema was somewhat lower (0.2-0.5% in 28S; 0.3-0.4% in ITS; 12-15.7% in ND1). Our comparison of DNA sequences along with morphologic study suggests Holarctic distribution of N. lisitsynae.

Molecular phylogeny of the Haplosplanchnata Olson, Cribb, Tkach, Bray and Littlewood, 2003, with a description of Schikhobalotrema huffmani n. sp

We describe Schikhobalotrema huffmani n. sp. from Tylosurus crocodilus (Péron and Leseur) (Belonidae) collected off Lizard Island, Great Barrier Reef, Queensland, Australia and Tylosurus gavialoides (Castelnau) collected from Moreton Bay, Queensland. Schikhobalotrema huffmani n. sp., along with Schikhobalotrema ablennis (Abdul-Salam and Khalil, 1987) Madhavi, 2005, Schikhobalotrema acutum (Linton, 1910) Skrjabin and Guschanskaja, 1955 and Schikhobalotrema adacutum (Manter, 1937) Skrjabin and Guschanskaja, 1955 are distinguished from all other species of Schikhobalotrema Skrjabin and Guschanskaja, 1955 in having ventral suckers which bear lateral lobes and have longitudinal apertures. Schikhobalotrema huffmani n. sp. differs from S. ablennis in having an obvious post-vitelline region and a longer forebody. From S. acutum, S. huffmani n. sp. differs in having a prostatic bulb smaller than the pharynx and more anterior testis. From S. adacutum, S. huffmani n. sp. differs in having more prominent ventral sucker lobes, a conspicuous prostatic bulb and a longer forebody. We also report the first Australian record of Haplosplanchnus pachysomus (Eysenhardt, 1829) Looss, 1902, from Mugil cephalus Linnaeus (Mugilidae) collected in Moreton Bay. Molecular sequence data (ITS2, 18S and 28S rDNA) were generated for Schikhobalotrema huffmani n. sp., H. pachysomus and archived specimens of Hymenocotta mulli Manter, 1961. The new 18S and 28S molecular data were combined with published data of five other haplosplanchnid taxa to expand the phylogeny for the Haplosplanchnata. Bayesian inference and Maximum Likelihood analyses recovered identical tree topology and demonstrated the Haplosplanchnata as a well-supported monophyletic group. However, relationships at and below the subfamily level remain poorly resolved.