Molecular Phylogeny of Pacific Archigregarines (Apicomplexa), Including Descriptions of Veloxidium leptosynaptae n. gen., n. sp., from the Sea Cucumber Leptosynapta clarki (Echinodermata), and Two New Species of Selenidium

Abstract

Although archigregarines are poorly understood intestinal parasites of marine invertebrates, they are critical for understanding the earliest stages in the evolution of the Apicomplexa. Previous studies suggest that archigregarines are a paraphyletic stem group from which other lineages of gregarines, and possibly all other groups of apicomplexans, evolved. However, substantiating this inference is difficult because molecular phylogenetic data from archigregarines, in particular, and other gregarines, in general, are severely limited. In an attempt to help fill gaps in our knowledge of archigregarine diversity and phylogeny, we set out to discover and characterize novel lineages of archigregarines with high-resolution light and scanning electron microscopy and analyses of small subunit (SSU) rDNA sequences derived from single-cell (SC) PCR techniques. Here, we describe two novel species of Selenidium, namely Selenidium idanthyrsae n. sp. and S. boccardiellae n. sp., and demonstrate the surface morphology and molecular phylogenetic position of the previously reported species S. cf. mesnili. We also describe a novel genus of archigregarine, Veloxidium leptosynaptae n. gen., n. sp., which branches with an environmental sequence and, together, forms the nearest sister lineage to a diverse clade of marine eugregarines (i.e. lecudinids and urosporids). This molecular phylogenetic result is consistent with the hypothesis that archigregarines are deeply paraphyletic within apicomplexans, and suggests that convergent evolution played an important role in shaping the diversity of eugregarine trophozoites.

A new view on the morphology and phylogeny of eugregarines suggested by the evidence from the gregarineAncora sagittata(Leuckart, 1860) Labbé, 1899 (Apicomplexa: Eugregarinida)

“…Three cases seemingly challenge the monophyly eugregarines at the morphological level: Veloxidium leptosynaptae , Caliculium glossobalani , and Seledinium melongena (Wakeman & Leander, 2012; Wakeman, Heintzelman & Leander, 2014; Wakeman et al, 2014). V. leptosynaptae and C. glossobalani broadly resemble archigregarines but SSU rDNA phylogenies unambiguously place them in the eugregarine clades Lecudinoidea and Gregarinoidea, respectively (Fig.…”

“…Molecular phylogenetic studies of gregarines are limited in sampling and largely rely on small subunit (SSU or 18S) ribosomal DNA (rDNA) sequences (Carreno, Martin & Barta, 1999; Leander, Clopton & Keeling, 2003; Leander, Harper & Keeling, 2003; Leander et al, 2006; Leander, 2007; Lepelletier et al, 2014; Rueckert & Leander, 2008, 2009, 2010; Clopton, 2009; Rueckert, Chantangsi & Leander, 2010; Rueckert et al, 2011, 2015; Rueckert, Villette & Leander, 2011; Rueckert, Wakeman & Leander, 2013; Wakeman & Leander, 2013a; Wakeman & Leander, 2012, 2013b; Wakeman, Heintzelman & Leander, 2014; Wakeman et al, 2014; Diakin, Wakeman & Valigurová, 2017). Gregarines have been also detected in environmental sequence surveys from various marine and freshwater samples, possibly because oocysts are stable in the environment (Rueckert et al, 2011; Janouškovec et al, 2015).…”

Parasites dominate hyperdiverse soil protist communities in Neotropical rainforests

“…Phylogenetic placements of query OTU representatives that were taxonomically assigned to the Apicomplexa were conducted using a full-length reference multiple sequence alignment and corresponding phylogeny comprising 190 taxa from all major Alveolate clades (see Supplementary Data 3 and 4 for GenBank accession numbers, sequences and clade assignments). The taxon sampling was collated from a range of publications relating to eukaryotic diversity in general and Alveolata diversity and phylogeny in particular; for example, refs 20,[63][64][65][66][67][68][69] . It is also acknowledged that single gene trees are unable to resolve the backbone of the Alveolate phylogeny.…”

Molecular Phylogeny of Marine Gregarine Parasites (Apicomplexa) from Tube‐forming Polychaetes (Sabellariidae, Cirratulidae, and Serpulidae), Including Descriptions of Two New Species of Selenidium

“…As such, the phylogenetic relationships between Selenidium species and other lineages of marine gregarines remain unclear (Leander , ; Leander et al. ; Rueckert and Leander ; Wakeman and Leander ).…”