Niels Van Steenkiste

• PhD
• Research Associate at University of British Columbia

Gregarines are a large group of apicomplexan parasites that infect a wide range of invertebrate hosts, including diverse and speciose groups, such as annelids and arthropods. Marine eugregarines represent the majority of gregarine diversity, but remain poorly understood, especially their deepest phylogenetic relationships. To expand knowledge of ma...

Trace fossils preserved with fossil worm-shaped remains suggest the presence of free-living flatworms during the Ordovician at the latest and their occurrence in terrestrial environments during the Permian. The presence of hooks associated with acanthodian and placoderm fishes indicates the existence of parasitic monopisthocotyleans, with a simple...

Marine microturbellarians are an assemblage of meiofaunal flatworms abundant in sediments and on seaweeds around the world. The diversity and distribution of these animals in Japan are poorly understood. Here, we provide an overview of all recorded species in Japan and characterize two new species of the rhabdocoel genus Reinhardorhynchus based on...

Microturbellarians are abundant and ubiquitous members of marine meiofaunal communities around the world. Because of their small body size, these microscopic animals are rarely considered as hosts for parasitic organisms. Indeed, many protists, both free-living and parasitic ones, equal or surpass meiofaunal animals in size. Despite several anecdot...

Symbiotic relationships between microbes and animals are incredibly common. However, most studies focus on the bacterial symbionts of vertebrate hosts and ignore both eukaryotic symbionts and invertebrate hosts. Some of the technical limitations complicating research into eukaryotic symbionts have largely been overcome, but there is an added wrinkl...

The marine microturbellarian diversity is scarcely known from the Pacific coastline of South America. The coastal margin of Peru is highly influenced by cold-water currents (Humboldt Current System). These cold-water currents play important roles in shaping the marine species diversity in this area. However, there are no previous records of marine...

Background Microbial symbioses in marine invertebrates are commonplace. However, characterizations of invertebrate microbiomes are vastly outnumbered by those of vertebrates. Protists and fungi run the gamut of symbiosis, yet eukaryotic microbiome sequencing is rarely undertaken, with much of the focus on bacteria. To explore the importance of micr...

Animals and microorganisms often establish close ecological relationships. However, much of our knowledge about animal microbiomes comes from two deeply studied groups: vertebrates and arthropods. To understand interactions on a broader scale of diversity, we characterized the bacterial microbiomes of close to 1,000 microscopic marine invertebrates...

We describe a new genus of dalytyphloplanid rhabdocoels, with seven new species. Orostylis gen. nov. has a unique combination of characters including the presence of a sclerotised stylet, an anteriorly positioned male copulatory organ with the male genital pore in the buccal cavity, and the absence of an oviduct. The ovary empties directly into the...

Rhabdocoels comprise a large group of flatworms that currently consists of two major subgroups: (1) Kalyptorhynchia with an anterior proboscis and (2) Dalytyphloplanida without a proboscis. Most genera of rhabdocoels can easily be classified into one of these two subgroups, except for the three monotypic representatives of the Mariplanellinae. Comp...

Many nominal species of microscopic animals traditionally fitting the ‘everything is everywhere’ paradigm have been revealed to be complexes of cryptic species. Here, we explore species diversity within the micrometazoan flatworm Gyratrix hermaphroditus—unique among meiofauna because of its global occurrence in a wide variety of brackish, freshwate...

A comprehensive morphological and taxonomic account of the members of the genus Cheliplana de Beauchamp, 1927 is presented. Six new species are described: Cheliplana asinaraensis n. sp., C. cubana n. sp., C. curacaoensis n. sp., C. hawaiiensis n. sp., C. longissima n. sp. and C. mauii n. sp. The new species are mainly distinguished from each other...

The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former studies. We introduce three new genera and twelve new species of Koinocystididae including Simplexcystis asymmetrica gen. n. sp. n., Galapagetula cubensis sp. n., eight species of Reinh...

Species of rhabdocoels within the family Dalyelliidae (Platyhelminthes) generally inhabit fresh water and are rare in marine and brackish environments. Here we describe a new species of marine dalyelliid, Grappleria corona gen. et sp. nov., from the Pacific coast of British Columbia. Based on the distinctive morphology of its male copulatory organ...

Marine gastrotrichs of the Pacific Ocean are poorly known. Here, we report on the finding of a marine chaetonotid gastrotrich of the genus Diuronotus from an intertidal beach within the Sea of Japan in Hokkaido (Japan). The Japanese individual shows a very close resemblance to Diuronotus aspetos. This new record is a consequential extension of its...

Gastrotricha and Platyhelminthes form a clade called Rouphozoa. Representatives of both taxa are main components of meiofaunal communities, but their role in the trophic ecology of marine and freshwater communities is not sufficiently studied. Traditional collection methods for meiofauna are optimized for Ecdysozoa, and include the use of fixatives...

To date, sea slugs have been considered the only animals known to sequester functional algal plastids into their own cells, via a process called “kleptoplasty.” We report here, however, that endosymbionts in the marine flatworms Baicalellia solaris and Pogaina paranygulgus are isolated plastids stolen from diatoms. Ultrastructural data show that kl...

Four new species of Paraustrorhynchus (Rhabdocoela: Kalyptorhynchia: Polycystididae) are described: two from Southern China (P. shenda n. sp., P. sinensis n. sp.), one from New Caledonia (P. isoldeae n. sp.), and one from India (P. smeetsae n. sp.). All four species show a typical dark blue dorsal pigmentation pattern, which is unique to the genus....

Kalyptorhynchs are abundant members of meiofaunal communities worldwide, but knowledge on their overall species diversity and distribution is poor. Here we report twenty species of eukalyptorhynchs associated with algae and sediments from the coastal margin of British Columbia. Two species, Paulodora artoisi sp. nov. and Limipolycystis castelinae s...

Rhabdocoel flatworms are abundant members of marine meiofaunal communities worldwide, contributing to a reservoir of biodiversity that thrives in sediments and on macroalgae. Yet, they are relatively understudied due to bias in meiofaunal collection techniques, time‐intensive identification and a lack of taxonomic expertise. Here, sampling of inter...

Increasing evidence suggests that many widespread species of meiofauna are in fact regional complexes of (pseudo-)cryptic species. This knowledge has challenged the 'Everything is Everywhere' hypothesis and also partly explains the meiofauna paradox of widespread nominal species with limited dispersal abilities. Here, we investigated species divers...

Rhabdocoels comprise a species-rich group of microturbellarians in marine habitats around the globe. Knowledge of their species diversity in the Northeast Pacific Ocean is limited to a few studies. Here we present nine species within Trigonostominae and one species within Brinkmanniellinae associated with intertidal algae, sandy beaches and mudflat...

Fifteen species of kalyptorhynch flatworms, twelve of them eukalyptorhynchs and three schizorhynchs, are reported from the KwaZulu-Natal coast in South Africa. Six species are new to science, five of which belong to Eukalyptorhynchia, the remaining one to Schizorhynchia. One of the new eukalyptorhynch species, Uncinorhynchus linusi n. sp., belongs...

Improving our understanding of species responses to environmental changes is an important contribution ecologists can make to facilitate effective management decisions. Novel synthetic approaches to assessing biodiversity and ecosystem integrity are needed, ideally including all species living in a community and the dynamics defining their ecologic...

Invasion impacts on indigenous biodiversity are poorly understood, in part because ecosystem dynamics depend on complex and often unresolved networks of interacting species. Improved understanding of these systems and the impacts of invasive species requires novel synthetic approaches to biodiversity and ecology assessments that would, ideally, cap...

Human-induced disturbances generate strong selection pressures on the ecology and evolution of species, affecting community dynamics, ecosystem functioning, and global processes. In the marine environment, the taxonomy and distribution of most organisms are poorly known. As ecologists strive to understand increasingly complex processes, involving a...

A morphological and taxonomical account of the taxon Phaenocora is provided. An effort was made to locate and study all available material and, where possible, species are briefly re-described. We also describe two new species: Phaenocora gilberti sp. nov. from Cootes Paradise, Ontario, Canada and Phaenocora aglobulata sp. nov. from Prairie Grove,...

Aquatic invasive species are transported via numerous human-mediated vectors and pose a significant risk to the Canadian economy and aquatic ecosystems. Early detection of new incursions can inform rapid response or other management interventions. Next generation sequencing technologies offer great promise for the early detection of invasive specie...

More than two decades ago, Gawor-Biedowa (1987) described a number of benthic foraminifers from Late Cretaceous deposits in Poland. At that time she proposed a new genus Varsoviella , although this name was already preoccupied by the validly named rhabdocoel flatworm Varsoviella Gieysztor and Wiszniewski, 1947. The foraminifer Varsoviella Gawor-Bi...

Canada has the longest coastline in the world and the potential risks posed by aquatic invasive species (AIS) to the Canadian economy and ecosystems are immense. Prevention and early detection of new invasions are critical. DNA barcoding has the potential to be used for rapid, cost-effective, and accurate identification of AIS from complex environm...

In this study we elaborate the phylogeny of Dalytyphloplanida based on complete 18S rDNA (156 sequences) and partial 28S rDNA (125 sequences), using a Maximum Likelihood and a Bayesian Inference approach, in order to investigate the origin of a limnic or limnoterrestrial and of a symbiotic lifestyle in this large group of rhabditophoran flatworms....

Majority-rule consensus tree from the Bayesian analysis of the 28S rDNA dataset. Legend identical to Fig. 2. (TIF)

Majority-rule consensus tree from the Bayesian analysis of the 18S rDNA dataset. Legend identical to Fig. 2. (TIF)

Identical sequences removed from the analyses. (DOC)

Test of substitution saturation with DAMBE v5.2.57 according to Xia's method for more than 32 OTUs. Analyses performed on all sites with gaps treated as unknown data. Subsets of 4, 8, 16 and 32 OTUs were randomly sampled 60 times and the test was performed for each subset. Iss: simple index of substitution saturation; Iss,cSym: critical Iss assumin...

List of species, sampling locations and amplification primers as used in this study. Additional sequences that were taken from GenBank are also listed with their GenBank accession number and when known, their sampling location. M: marine; F: freshwater; B: brackish water; L: limnoterrestrial; S: symbiotic. (DOC)

Nine taxa of Dalyelliidae Graff, 1908 collected from limnic habitats in Ontario, Canada and Michigan and Alabama, USA are discussed. Two taxa are new to science. Pseudodalyellia alabamensis n. gen. n. sp. has a unique combination of characters (Microdalyellia-type stylet with two proximal heteromorphic axes of different size and two distal axes wit...

Nineteen taxa of Dalytyphloplanida Willems et al., 2006 collected from southwestern Andalusia are discussed. Although most taxa were found in freshwater, three are marine, one occurred in brackish water and Protoplanella simplex Reisinger, 1924 was even collected in a dry, limnoterrestrial habitat. Four taxa are new to science. Castrada purgatorial...

Bryoplana xerophila, a new genus and species of limnoterrestrial protoplanelline platyhelminth, was found in moss and soil covering a concrete wall in northern Alabama, USA. Bryoplana xerophila is the first taxon of limnoterrestrial Protoplanellinae recorded from North America and is one of the few rhabdocoels known from dry habitats. It is unique...

An overview of the marine rhabdocoel fauna of Uruguay is given. Eight species, new to science, are described and discussed. Two of these, Acirrostylus poncedeleoni n.g. n.sp. and Polliculus cochlearis n.g. n.sp. could not be placed in any existing genera. A. poncedeleoni n.g. n.sp. can be recognized from other Cicerinidae Meixner, 1928 by the fact...

An overview of the marine rhabdocoel fauna of Uruguay is given. Eight species, new to science, are described and discussed. Two of these, Acirrostylus poncedeleoni n.g. n.sp. and Polliculus cochlearis n.g. n.sp. could not be placed in any existing genera. A. poncedeleoni n.g. n.sp. can be recognized from other Cicerinidae Meixner, 1928 by the fact...

FIGURE 2. Acirrostylus poncedeleoni n. g. n. sp. Reconstruction of the proboscis from the right side.

FIGURE 3. Oneppus lacus Marcus, 1954 (A) Habitus of a live animal. (B) Reconstruction of the proboscis from the right side. (C) Cirrus (arrow indicates the proximal crown of larger spines).

FIGURE 4. Cheliplana triductibus n. sp. (A) Habitus of a live animal. (B) Cirrus and accessory cirrus of two different specimens (the left one is from the holotype). (C) Proboscis with teeth. (D) Reconstruction of the entire animal from the right side.

FIGURE 7. Baicalellia forcipifera n. sp. (A) Reconstruction of the anterior body part from the right side. (B) Stylet (upper from the holotype). (C) Reconstruction of the atrial organs from the left side.

FIGURE 8. Baicalellia forcipifera n. sp. (A) Habitus of a live animal. Polliculus cochlearis n. g. n. sp. (B) General organisation of an animal based on serial sections. (C) Stylet and accessory stylet (from the paratype). (D) Reconstruction of the atrial organs from the right side (arrow indicates intracapsular seminal vesicle).

FIGURE 1. Acirrostylus poncedeleoni n. g. n. sp. (A) Habitus of a live animal. (B) Stylet from the holotype. (C) Reconstruction of the entire animal from the right side.

FIGURE 5. Cheliplana uruguayensis n. sp. (A) Habitus of a live animal. (B) Reconstruction of the entire animal.

FIGURE 10. Vauclusia multistriata n. sp. (A) Reconstruction of the entire animal. (B) Reconstruction of the atrial organs. (C) Stylet with internal ridges (from holotype).

FIGURE 9. Lurus evelinae Marcus, 1950 (A) Habitus of a live animal. (B) Stylet. Vauclusia multistriata n. sp. (C) Habitus of a live animal.

FIGURE 6. Carcharodorhynchus viridis n. sp. (A) Habitus of a live animal. (B) Proboscis of two different specimens. (C) Copulatory apparatus with cirrus and stylet (from the holotype).

FIGURE 11. Coronhelmis mimosa n. sp. (A) Habitus of live animal. (B) Stylet (right one from holotype). Byrsophlebs caligulachaena (Ehlers & Ehlers, 1981) Karling, 1985 (C) Habitus of live animal. Ceratopera axi (Riedl, 1954) Den Hartog, 1964 (D) Bursal appendage. (E) Stylet.