Characterization of Tulamoeba bucina n. sp., an Extremely Halotolerant Amoeboflagellate Heterolobosean Belonging to the Tulamoeba–Pleurostomum Clade (Tulamoebidae n. fam.)

Abstract

Most protozoans that have been cultivated recently from high salinity waters appear to be obligate halophiles. Phylogenetic analyses indicate that these species mostly represent independent lineages. Here, we report the cultivation, morphological characterization, and phylogenetic analysis of two strains (XLG1 and HLM-8) of a new extremely halotolerant heterolobosean amoeboflagellate. This species is closely related to the obligate halophiles Tulamoeba peronaphora and Pleurostomum flabellatum, and more specifically to the former. Like Tulamoeba, the new species has a monopodial limax amoeba stage, however, its cyst stage lacks an intrusive pore plug. The flagellate stage bears a combination of a planar spiral feeding apparatus and unequal heterodynamic flagella that discriminates it from described Pleurostomum species. Strain XLG1 grows at salinities from 35‰ to 225‰. This degree of halotolerance is uncommon in protozoa, as most species showing growth in seawater are unable to grow at 200‰ salinity. The unrelatedness of most halophilic protozoa suggested that independent colonization of the hypersaline environment is more common than speciation within it. However, this study supports the idea that the Tulamoeba-Pleurostomum clade underwent an adaptive radiation within the hypersaline environment. A new species Tulamoeba bucina n. sp. is described, with Tulamoebidae n. fam. proposed for the Tulamoeba-Pleurostomum clade.

Dactylomonas gen. nov., a Novel Lineage of Heterolobosean Flagellates with Unique Ultrastructure, Closely Related to the Amoeba Selenaion koniopes Park, De Jonckheere & Simpson, 2012

“…The flagellate stage is unknown in the genus Neovahlkampfia (tetramitian clade I), which has been formally assigned into the nonmonophyletic family Vahlkampfiidae (Brown and de Jonckheere ); however, it represents a deep lineage of Tetramitia, branching between Selenaionida and Eutetramitia in the SSU rRNA gene trees (e.g., Kirby et al. ; Pánek et al. ; Park and Simpson ; Tyml et al.…”

“…The other two lineages are represented by the obligate anaerobe Creneis carolina (Creneidae) and the possibly anaerobic Pleurostomum flabellatum (Tulamoebidae, a part of tetramitian clade III), respectively (Kirby et al. ; Pánek et al. ; Park et al.…”

Characterization of a Deep‐Branching Heterolobosean, Pharyngomonas turkanaensis n. sp., Isolated from a Non‐Hypersaline Habitat, and Ultrastructural Comparison of Cysts and Amoebae Among Pharyngomonas Strains

“…However, Monopylocystis , Stachyamoeba , and Tulamoeba at least have recently been shown to be amoeboflagellates, or at least to include amoeboflagellate species (Kirby et al. ; Murase et al. ; Pánek et al.…”

“…However, Tulamoeba bucina , which is specifically related to T. peronaphora , is a halotolerant species (Kirby et al. ). As in the case of T. bucina , adaptation of P. turkananensis isolate LO to a mesohaline environment appears to derive “secondarily” from obligate halophile ancestors.…”

A New Heterolobosean Amoeboflagellate, Tetramitus dokdoensis n. sp., Isolated from a Freshwater Pond on Dokdo Island in the East Sea, Korea

“…Recently, at least Monopylocystis , Stachyamoeba , Tulamoeba , Pseudoharpagon , and Pharyngomonas, all originally considered to be either amoebae or flagellates only, have been reevaluated to be amoeboflagellates, or at least to contain amoeboflagellate species (Kirby et al. ; Murase et al. ; Pánek et al.…”