Description of Trichotokara nothriae n. gen. et sp. (Apicomplexa, Lecudinidae) – An intestinal gregarine of Nothria conchylega (Polychaeta, Onuphidae) Sonja Rueckert * , Brian S. Leander Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Departments of Botany and Zoology, University of British Columbia, #3529 – 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4 article info Article history: Received 12 November 2009 Accepted 11 March 2010 Available online 23 March 2010 Keywords: Alveolata Apicomplexa Lecudinidae Lecudina Parasite Phylogeny Polychaete Trichotokara nothriae abstract The trophozoites of a novel gregarine apicomplexan, Trichotokara nothriae n. gen. et sp., were isolated and characterized from the intestines of the onuphid tubeworm Nothria conchylega (Polychaeta), collected at 20 m depth from the North-eastern Pacific Coast. The trophozoites were 50–155 lm long with a mid-cell indentation that formed two prominent bulges (anterior bulge, 14–48 lm wide; posterior bulge, 15– 55 lm wide). Scanning electron microscopy (SEM) demonstrated that approximately 400 densely packed, longitudinal epicytic folds (5 folds/lm) inscribe the surface of the trophozoites, and a prominently elon- gated mucron (14–60 lm long and 6–12 lm wide) was covered with hair-like projections (mean length, 1.97 lm; mean width, 0.2 lm at the base). Although a septum occurred at the junction between the cell proper and the mucron in most trophozoites, light microscopy (LM) demonstrated that the cell proper extended into the core of the mucron as a thin prolongation. A spherical nucleus (8–20 lm) was situated in the middle of the trophozoites, and gamonts underwent caudal syzygy. The small subunit (SSU) rDNA sequence and molecular phylogenetic position of T. nothriae was also characterized. The sequence from this species was the most divergent of all SSU rDNA sequences currently known from gregarines and formed a weakly supported clade with Lecudina polymorpha, which also possesses densely packed epicyc- tic folds (3–5 folds/lm) and a prominently elongated mucron. Ó 2010 Elsevier Inc. All rights reserved. 1. Introduction Apicomplexans form a diverse group of unicellular parasites containing about 6000 described species and approximately 1.2– 10 million undescribed species (Hausmann et al., 2003; Adl et al., 2007; Morrison, 2009). There are four major groups of apicomplex- ans recognized: (eu)coccidians, haemosporidians, piroplasmids and gregarines (Adl et al., 2005). Because some of these groups in- clude pathogens of humans and life stock (e.g., Plasmodium – the causative agent of malaria), these species are better studied than groups that have no known medical or economic impact. Among the least understood apicomplexan parasites are gregarines, espe- cially those inhabiting the oceans. Marine gregarines are dynamic extracellular parasites that inhabit the intestines and coeloms of invertebrates, and improved knowledge of these lineages will help elucidate the overall diversity and early evolutionary history of apicomplexans as a whole (Leander, 2008). Gregarines have been conveniently lumped into three groups: archigregarines, eugregarines, and neogregarines (Grassé, 1953). The vast majority of described gregarine species are considered eugregarines, and, in large part, this is due to the fact that many eugregarines infect insects, which have garnered more attention from the parasitological community. Eugregarines, however, also occur in marine and freshwater habitats and have intestinal tro- phozoites (relatively large feeding stages) that are significantly dif- ferent in morphology and behaviour from that of the infective sporozoites. Most eugregarine species that inhabit marine inverte- brates have been classified within a poorly circumscribed family called the Lecudinidae Kamm, 1922 (25 genera) and within the genus Lecudina Mingazzini, 1899 (Levine, 1988). This genus has emerged as a ‘‘catch-all” taxon for marine aseptate gregarines that inhabit the intestines of polychaetes (and a few other host taxa). Consequently, the actual diversity of these parasites is greatly underestimated, and the identity and composition of Lecudina has become even more ill-defined within the context of modern molecular phylogenetic and comparative ultrastructural data (Leander et al., 2003b; Leander, 2008; Rueckert and Leander, 2009). New species (i.e., morphotypes or phylotypes) of gregarines are generally discovered in previously unexplored host species, and closely related host species tend to be infected by closely related gregarine species (e.g., Levine, 1979; Perkins et al., 2000; Landers and Leander, 2005; Rueckert and Leander, 2008, 2009; Simdyanov, 0022-2011/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jip.2010.03.005 * Corresponding author. Address: Departments of Botany and Zoology, University of British Columbia, #3529 – 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4. Fax: +1 604 822 6089. E-mail address: rueckert@interchange.ubc.ca (S. Rueckert). Journal of Invertebrate Pathology 104 (2010) 172–179 Contents lists available at ScienceDirect Journal of Invertebrate Pathology journal homepage: www.elsevier.com/locate/jip