Morphology and Gene Sequence of Levicoleps biwae n. gen., n. sp. (Ciliophora, Prostomatida), a Proposed Endemic from the Ancient Lake Biwa, Japan

Abstract

Levicoleps biwae n. gen., n. sp. was discovered in organic mud on the shore of Lake Biwa, Japan. Its morphology and small subunit rRNA gene sequence were studied with standard methods. Further, we established a terminology for the colepid armour and selected four features for genus recognition: the number of armour tiers, the structure of the tier plates, the presence/absence of armour spines, and the number of adoral organelles (three or five). The Japanese colepid, a barrel-shaped ciliate with an average size of 75 x 45 microm, has six armour tiers and hirtus-type tier plates, but lacks armour spines, both in the environment and in laboratory culture. Thus, it is considered to represent a new genus. This rank is supported by the considerable genetic distance (7%) from the common Coleps hirtus. Although L. biwae looks quite similar to C. hirtus in vivo, it is very likely most closely related to Coleps amphacanthus, a species with conspicuous armour spines, as indicated by body size, the number of ciliary rows and, especially, the multiple caudal cilia. Lake Biwa is about four million years old and inhabited by many endemic organisms, ranging from algae to large fish. Thus, we suspect that L. biwae is restricted to Lake Biwa or, at least, to Asia. Based on literature data and the generic features established, we also propose the new genus Reticoleps for Coleps remanei Kahl, 1933, and resurrect the genus Pinacocoleps Diesing, 1865 to include Coleps incurvus Ehrenberg, 1833, Coleps pulcher Spiegel, 1926, Coleps tessalatus Kahl, 1930 and, probably, Baikalocoleps quadratus Obolkina, 1995a. Nine colepid genera are diagnosed and dichotomously keyed.

Molecular phylogeny ofNothoholosticha(Protozoa, Ciliophora, Urostylida) and systematic relationships of theHolosticha-complex

“…Phylogenetic relationships among members of the Holosticha-complex species, represented by eight marine species and one eurytopic species, and between these species and other spirotricheans, are also investigated. The SSrRNA gene was chosen because the vast majority of molecular phylogenies of ciliate taxa have been based on SSrRNA gene sequence comparisons (for example, Gong et al, 2007aGong et al, , 2007bFoissner et al, 2008;Gao et al, 2008;Yi et al, 2008a). However, the low SSrRNA sequence divergence among the stichotrichs hampers phylogenetic analysis and makes it very sensitive to undersampling (Foissner et al, 2004).…”

The symbiotic life ofSymbiodiniumin the open ocean within a new species of calcifying ciliate (Tiarinasp.)

“…Compared with T. fusus, the newly isolated ciliate has a larger length-to-width ratio (1.5 times more), lacks armor spines and possesses long somatic cilia arranged in 18 or more ciliary rows (T. fusus has 15-17 longitudinal rows; Supplementary Table S7). As shown by brightfield (on more than 50 cells) and confocal (on 10 cells) microscopy images (Figures 1d and e and Supplementary Figure S2), another distinct morphological character of the isolated ciliate is the presence of 10 to 25 intracellular microalgal cells that has never been reported in T. fusus (Foissner et al, 2008;Lynn, 2008;Chen et al, 2012). Kahl (1930) observed 'ingested dinoflagellates' ('Nahrung kleine Peredineen') in the arctic species T. meunieri but this old and succinct description has not been confirmed in the literature.…”

“…Both taxa live in marine waters and display a fusiform and elongated body with large longitudinal rows of calcium carbonate plates arranged in six different regions (called 'tiers'), as well as a wing-like structure that is absent in other Colepidae species (Figures 1a and b; Chen et al, 2012). These morphological commonalities, which are typically used for genus recognition within the Colepidae (Foissner et al, 2008), lead us to argue that the newly isolated ciliate belongs to the genus Tiarina, Berg 1881. In addition to T. fusus, the genus Tiarina is composed of several species including T. meunieri, T. borealis, T. antarctica and T. levigata, but these have very old, incomplete morphological descriptions without reference microscopy images or molecular data.…”

Taxonomic studies on a new marine ciliate, Apocoleps magnus gen. nov., spec. nov. (Ciliophora, Colepidae), isolated from Qingdao, China

“…The number of armour tiers is an important character for genus distinction as demonstrated by Foissner et al (2008). Currently, ten genera are assigned to the family Colepidae: Baikalocoleps Obolkina, Coleps Nitzsch, Kotinia Obolkina in Aescht, Levicoleps Foissner et al, Macrocoleps Obolkina, Nolandia Small and Lynn, Pinacocoleps Diesing, Planicoleps Dragesco and DragescoKernéis, Reticoleps Foissner et al, and Tiarina Bergh (Bergh, 1881;Diesing, 1865;Dragesco and DragescoKernéis, 1991;Foissner et al, 2008;Nitzsch, 1827;Obolkina, 1995;Small and Lynn, 1985).…”

“…Colepid ciliates are characterized by their cylindrical or barrel-shaped body bearing unique calcified cuirass (armoured plates with small lateral teeth arranged in longitudinal rows) (Corliss, 1979;Dragesco and DragescoKernéis, 1991;Foissner et al, 2008;Kahl, 1930;Obolkina, 1995). Ten genera are currently assigned to the family Colepidae and these are separated mainly by the following features: the number of armour tiers, the presence or absence of armour spines, the type of tier plates, and the number of adoral organelles (Dragesco and Dragesco-Kernéis, 1991;Foissner, 1983Foissner, , 1984Foissner et al, 1994Foissner et al, , 1999Foissner et al, , 2008Kahl, 1930Kahl, , 1935Lynn, 2008;Noland, 1937;Obolkina, 1995;Small and Lynn, 1985;Wilbert and Schmall, 1976).…”