The ability to detect food in the environment is an essential function among all living organisms and must have arisen at the beginning of life. The anatomical, morphological and molecular features involved in taste and smell may differ among disparate groups, but the principle of chemoreception is conserved. Here we debate the sense of taste and smell in the feeding behaviour of the unicellular protist, Acanthamoeba. 

The genus Calciarcus is revisited here with the purpose of providing, based on additional sampling from both polar regions, an update on species diversity and morphology that can serve as a reference for future work. The geographic realm of the genus is significantly widened and a case is built based on consistency in appearance in favour of adding Calciarcus spp. to the well-defined community of bipolar weakly calcified coccolithophorid genera. Despite the multitude of specimens available for analysis and the fact that the specimens examined distribute themselves within three clusters based on morphological features of coccolith superstructures, it has not been possible at this stage to define a robust framework for differentiation among species of Calciarcus. Circumstantial evidence exist linking species of Wigwamma with species of Calciarcus in haploid-diploid life cycles.

There is a widespread belief that spathidiids have few morphological features. In contrast, we show a rich morphological diversity in five new species discovered in tank bromeliads from the Caribbean, using live observation; protargol impregnation; morphometry; scanning electron microscopy; and resting cyst morphology, demonstrating lepidosomes (organic scales) for the first time in spathidiid haptoria. Arcuospathidium bromelicola nov. spec. is very similar to the previously described A. muscorum but its resting cyst has conspicuous, pillar-shaped lepidosomes on the surface. Protospathidium lepidosomatum nov. spec. is very similar to the previously described P. muscicola but has outstanding, nipple-shaped (vs. conical) lepidosomes on the cyst surface. Spathidium bromeliophilum nov. spec., whose ontogenesis is highly similar to that of S. turgitorum, differs from similar species by the body length:width ratio, the number of ciliary rows, the shape of the oral bulge, and details of the ciliary pattern. Spathidium bromelicola nov. spec. is similar to S. muscicola (extrusomes bluntly fusiform and 4 µm long vs. rod-shaped and > 15 µm long) and S. stammeri (resting cyst wall smooth vs. spinous). Spathidium wolfi nov. spec. has an anterior and a posterior contractile vacuole. It differs from the supposed nearest relative, S. faurefremieti, by body size (on average 135 × 25 µm vs. 240 × 17 µm), the shape of the macronucleus (moniliform vs. a long, tortuous strand), and the total number of dorsal brush bristles (on average 47 vs. 72). The bent oral bulge of Arcuospathidium bromelicola and Spathidium bromeliophilum as well as the occurrence of lepidosomes on the cyst surface of Arcuospathidium bromelicola and Protospathidium lepidosomatum are discussed.

A new soil ciliate, Pseudouroleptus jejuensis, was discovered from Jeju Island, South Korea and described based on live observation, protargol impregnation, and SSU rRNA gene sequence analyses. Pseudouroleptus jejuensis differs from other congeneric species mainly by number of dorsal kineties (5 vs. 4). Based on our observation of late dividers, we confirm that the dorsal kinety anlage 3 forms 3 kineties (i.e., dorsal kineties 3–5), and the dorsal kinety anlagen 1–3 form 3–5/1–2/0 caudal cirri, respectively. Our gene trees support the assignment of this new species in Pseudouroleptus to full supporting values.

Mitochondrial SSU-rDNA has been used recently to infer phylogenetic relationships among a few ciliates. Here, this locus is compared with nuclear SSU-rDNA for uncovering the deepest nodes in the ciliate tree of life using broad taxon sampling. Nuclear and mitochondrial SSU-rDNA reveal the same relationships for nodes well-supported in previously-published nuclear SSU-rDNA studies, although support for many nodes in the mitochondrial SSU-rDNA tree are low. Mitochondrial SSU-rDNA infers a monophyletic Colpodea with high node support only from Bayesian inference, and in the concatenated tree (nuclear plus mitochondrial SSU-rDNA) monophyly of the Colpodea is supported with moderate to high node support from maximum likelihood and Bayesian inference. In the monophyletic Phyllopharyngea, the Suctoria is inferred to be sister to the Cyrtophora in the mitochondrial, nuclear, and concatenated SSU-rDNA trees with moderate to high node support from maximum likelihood and Bayesian inference. Together these data point to the power of adding mitochondrial SSU-rDNA as a standard locus for ciliate molecular phylogenetic inferences.

Genus Perkinsus Levine, 1978 (Alveolata, Perkinsidae) an intracellular pathogenic parasite is described from the mantle and gill filaments of a commercially important clam, Meretrix meretrix, collected from the Arabian Gulf, Saudi Arabia. This genus contains currently seven named species: P. marinus, P. olseni (P. atlanticus), P. chesapeaki (P. andrewsi), P. mediterraneus, P. honshuensis, P. beihaiensis and P. qugwadi. Meanwhile, some unnamed Perkinsus sp. have been described in wide variety of mollusc species. Ultrastructural features of Perkinsus sp. trophozites and the host reaction are described. The different developmental stages of trophozoites appeared as single or grouped cells surrounded by amorphous material that constituted cysts or nodules randomly distributed throughout the connective tissue of the mantle. The early trophozoites were generally spherical to ellipsoidal with a circular nucleus containing a prominent central nucleolus. The cytoplasm had several small vacuoles which coalesce to form a great vacuole in the later trophozoites and the nucleus becomes eccentric. Some lomosomes were observed between the wall and the plasmalemma of trophozoites. A large number of degraded and pyknotic cell and several cellular structure with lysed aspects were encountered in the surrounding area near the cysts. Ultrastructural data showed that the lysed granular cells and the coalescence of the granules result in the cyst that encapsulates various trophozoites. In the current study, we describe for the first time the presence of Perkinsus sp. as well as the host reaction in clams from the Saudi Arabian coasts.

Cilia and Flagella – Ciliates and Flagellates: Ultrastructure and cell biology, function and systematics, symbiosis and biodiversity  edited by Klaus Hausmann and Renate Radek. Stuttgart: Schweizerbart Science Publishers. 2014. 299 pp. Hardback ISBN 978-3-510-65287-7.  € 39.80