Levisunguis subaequalis n. g., n. sp., a tongue worm (Pentastomida: Porocephalida: Sebekidae) infecting softshell turtles, Apalone spp. (Testudines: Trionychidae) in the southeastern United States

Systematic assessment of nymphs of Diesingiinae (Pentastomida: Sebekidae) parasitizing Palloceros harpagos (Cyprinodontiformes: Poeciliidae) from Parque Nacional Iguazú, Argentina: filling gaps in an incomplete phylogenetic framework

During a search for parasites in fishes from Iguazu River, Argentina, a nymph of pentastomid was found encysted on mesenteries of Phalloceros harpagos. The 28S rDNA and COI mt-DNA were used to compare with the sequences deposited in the GenBank. Pentastomid nymphs belong to the subfamily Diesingiinae (Sebekidae) for having chloride cell pores distributed in a single row per annulus; also, the hooks and rows of spines of our material differ to other genera. Present specimens are most likely Diesingia sp., having 63-74 annuli, a U shaped oral cadre with fibers closing anteriorly and a peg like extension of the oral cadre. The 28S rDNA analysis places our samples into a sister group of Alofia sp., but the COI mt-DNA situate them on the base of the clade. In conclusion, our pentastomid positively belongs to Diesingia sp., however, indisputable assignation requires a reliable description of the nymph, or the availability of sequences linking nymphs and adults, which even could provide evidence of a new hitherto undescribed genus. Aditionally, the systematic position of Sebekia oxycephala previously described by P. harpagos is discussed on the basis of our results, allowing us to suggest a re-assignation of such specimens to the genus Diesingia.

Variation in Helminth Parasite Component Communities of Gambusia affinis

In north-central Texas streams, seasonal changes in ambient temperature and rainfall result in dynamic variation in microhabitat structure, affecting the distribution and abundance of hosts. Since the complex life cycles of parasites require the presence and interaction of multiple hosts, the seasonal variations in microhabitats could influence parasite component communities within these ecosystems. Gambusia affinis (western mosquitofish) serves as a host for a variety of larval and adult parasites. Factors that affect helminth component communities in populations of mosquitofish from the Paluxy River were investigated in this study. Gambusia affinis individuals were collected from 3 sites monthly from June 2015 through August 2016. All helminth parasites were collected during necropsy and subsequently identified. From 495 mosquitofish, 5,283 helminths were collected. Component community diversity varied among collection sites and collection dates and was positively influenced by river flow. These results indicate that helminth assemblages infecting mosquitofish in the Paluxy River vary through time and space, as well as in response to environmental variation (i.e., changes in water flow).

Molecular and Histopathological Data on Levisunguis subaequalis Curran, Overstreet, Collins & Benz, 2014 (Pentastomida: Eupentastomida: Porocephalida: Porocephaloidea: Sebekidae: Sebekinae) from Gambusia affinis in Alabama, USA

Levisunguis subaequalis Curran, Overstreet, Collins & Benz, 2014 , was recently described from the lungs of the definitive hosts, softshell turtles, Apalone ferox (Schneider, 1783), and Apalone spinifera aspera (Agassiz, 1857) as well as the viscera of an intermediate host, the western mosquitofish, Gambusia affinis (Baird and Girard, 1853). However, the original account lacked molecular data. Furthermore, histological examination of infected host tissues in the original account of L. subaequalis did not reveal any pathological changes in the intermediate host. The present work provides a robust morphological description of the nymph and novel molecular data from the 18S and 28S ribosomal gene regions and the cytochrome c oxidase subunit 1 (COI) mitochondrial gene. Phylogenetic analyses using Bayesian inference and maximum likelihood analysis with concatenated sequence data from these 3 regions, as well as each region individually, placed the turtle pentastomid L. subaequalis as a sister clade to the crocodilian pentastomids of the genus Sebekia Sambon, 1922. While only concatenated phylogenetic analyses agreed with the currently accepted classification of the Eupentastomida and phylogenetic signal assessment indicated that the concatenated data set yielded the most phylogenetic signal, data from more taxa are still needed for robust phylogenetic inferences to be made. The intensity of infection ranged from 2 to 171 nymphs per fish, compared with the highest previously reported intensity of 6. These high-intensity infections with L. subaequalis were characterized by the nymphs occupying 5-50% of the coelomic cavity of G. affinis. However, despite this heavy parasite infection, fish exhibited minimal pathology. Observed pathology was characterized by compression or effacement of organs adjacent to the nymphs, particularly liver, swim bladder, and intestines, as well as the formation of granulomas around shed pentastomid cuticles. Nonetheless, the morphological and molecular data provided in the present work will bolster future efforts to identify this pentastomid in other hosts where pathology may be present in addition to aiding in the advancement of the field of molecular pentastomid systematics.