Midventral Cirri Research Articles

New record of Apoholosticha sinica (Ciliophora, Urostylida) from the UK: morphology, 18S rRNA gene phylogeny and notes on morphogenesis

The benthic urostylid ciliate Apoholosticha sinicaFan et al., 2014 was isolated from a salt marsh at Blakeney, UK, and reinvestigated using light microscopy and small-subunit rRNA gene sequencing. Morphologically, it corresponds well with the original description. Several stages of divisional morphogenesis and physiological reorganization were also observed from which the following could be deduced: (i) the oral apparatus is completely newly built in the proter; (ii) frontal-ventral-transverse cirral anlage II does not produce a buccal cirrus; (iii) each of the posteriormost three or four anlagen contributes one transverse cirrus at its posterior end; (iv) a row of frontoterminal cirri originates from the rearmost frontal-ventral-transverse cirral anlage; (v) the last midventral row is formed from the penultimate frontal-ventral-transverse cirral anlage. Based on new data, two diagnostic features were added to the genus definition: (i) the midventral complex is composed of midventral pairs and midventral row and (ii) pretransverse ventral cirri are absent. Based on a combination of morphological and morphogenetic data, the genus Apoholosticha is assigned to the recently erected subfamily Nothoholostichinae Paiva et al., 2014, which is consistent with sequence comparison and phylogenetic analyses based on SSU rRNA gene data. It is also concluded that this benthic species, previously reported only from China, is not an endemic form.

Morphology and molecular phylogeny of Apoterritricha lutea n. g., n. sp. (Ciliophora, Spirotrichea, Hypotrichia): a putative missing link connecting Cyrtohymena and Afrokeronopsis.

A new hypotrichous ciliate, Apoterritricha lutea n. g., n. sp., was discovered in a sample of a terrestrial liverwort from Korea. Its morphology was studied using detailed in vivo observation and protargol impregnation. Its phylogenetic relationships were revealed by analyses of the 18S rRNA gene. This new taxon is characterized by a combination of the following traits: (i) ellipsoidal to narrowly ellipsoidal body with an average size of 230×85μm; (ii) two macronuclear nodules and two to five micronuclei; (iii) golden yellow cortical granules, forming small groups along the microtubular appendages of cirri, adoral membranelles, and dorsal kineties; (iv) typically three frontal cirri, one buccal cirrus, four frontoventral cirri, seven midventral cirri, two pretransverse cirri, seven transverse cirri, ca. 38 left, and ca. 36 right marginal cirri; and (v) on average six dorsal kineties, three dorsomarginal kineties, and three caudal cirri. In molecular phylogenies, A. lutea clusters with strong support within a clade containing Afrokeronopsis aurea and several "typical" oxytrichids having golden yellow to brown cortical granules. In this light we propose a hypothesis that is not unambiguously rejected by the present phylogenetic analyses, which shows how the Afrokeronopsis-like pattern could have evolved from a Rubrioxytricha-like ancestor via an Apoterritricha-like stage by cirri-multiplication.

Redescription of a Poorly Known Marine Ciliate, Leptoamphisiella vermis Gruber, 1888 n. g., n. comb. (Ciliophora, Stichotrichia, Pseudoamphisiellidae), from the Yellow Sea, China

Leptoamphisiella vermisGruber, 1888 n. g., n. comb. (basionym Epiclintes vermisGruber, 1888) is an extraordinarily large and worm-like marine stichotrichous ciliate. Based on a population isolated recently from coastal waters of Qingdao, China, the living morphology and infraciliature are redescribed and its taxonomic position is defined. Accordingly, a new diagnosis for this species is suggested: large, marine Leptoamphisiella with a conspicuous layer of pellicular alveoli; 400-1000 microm x 40-70 microm in vivo; body band-like, highly flexible; about 40 membranelles; always three frontal and two buccal cirri; 52-80 transverse cirri (TC) extending to the posterior end of the buccal field; 57-79 left midventral and 44-62 right midventral cirri; 62-102 cirri in left and 63-91 cirri in right marginal rows (MR); 9-13 dorsal kineties that extend the full body length; about 100 macronuclear nodules and 5-13 micronuclei. The diagnosis for the new genus is as follows: vermiform Pseudoamphisiellidae with strongly contractile body, differentiated frontal, buccal, and highly developed TC; two remarkably separated midventral rows; one MR on each side of the body; frontoterminal and caudal cirri absent. Leptoamphisiella vermis n. comb. is fixed as the type species of the new genus.

Benthic ciliates from Sepetiba Bay (Rio de Janeiro, Brazil) with description of Pseudokeronopsis sepetibensis n. sp. (Spirotrichea: Urostylida)

During the period from 2001 to 2002, we examined samples of water and sediment from five stations in Sepetiba Bay, located in the south region of Rio de Janeiro state, Brazil. We identified 32 species of ciliate protists representing seven classes: Karyorelictea, Heterotrichea, Spirotrichea, Litostomatea, Phyllopharyngea, Protostomatea and Oligohymenophorea. Among the Spirotrichea, we discovered Pseudokeronopsis sepetibensis n. sp., characterized by a unique combination of three features: 3 contractile vacuoles, an inconspicuous mid-ventral row, and 4 5 frontoterminal cirri. It showed yellow-greenish coloration and elongated body outline (100 140 m x 20 26 m). On average, there were 44 adoral membranelles, 50 left marginal cirri, 48 right marginal cirri and 41 mid-ventral cirri disposed in a straight row past the level of the oral region. Other features include 4 frontoterminal cirri and a constant number of 3 transverse cirri; 8 frontal cirri (4 anterior and 4 posterior arranged as an atypical bicorone).

Divisional morphogenesis in the marine ciliate Holosticha warreni (Ciliophora: Hypotrichida)

The cortical development of the marine hypotrichous ciliate Holosticha warreni, found in coastal waters near Qingdao, China, was investigated using the protargol impregnation method. In the proter, disorganization of the parental adoral zone of membranelles and undulating membranes contributes to the formation of its oral primordia which replace the parental buccal apparatus completely. Cirral anlagen in both division parts derive from the breaking of primary primordia. Most midventral cirri join in the formation of these primordia which occurs de novo separately from the oral primordia. Each of the 11 to 13 oblique streaks divides into three segments (new cirri) while the last two anlagen produce four each. Two frontoterminal cirri derive from the posteriormost anlage. The marginal rows develop from the parental structure. The generation mode of dorsal kineties is of the ‘one group type’ without forming caudal cirri.

Morphology and morphogenesis of Thigmokeronopsis antarctica nov. spec, and T. crystallis nov. spec. (Ciliophora, hypotrichida) from Antarctic Sea Ice

Summary The morphology and morphogenesis of Thigmokeronopsis antarctica nov. spec, and T. crystallis nov. spec, discovered in brine channels of Antarctic sea ice, were investigated using protargol silver impregnation. Both species are characterized by a left postoral ciliary field which is composed of much fewer longitudinal files than in T. jahodai, the type species of the genus. In addition, the new species have unique morphogenetic features, viz. all marginal and dorsal primordia originate de novo and the macronuclear nodules fuse incompletely during cell division. Thigmokeronopsis antarctica is distinguished from T. jahodai by shortened midventral rows, 1 left postoral file and 3–4 buccal cirri; transverse cirri are perhaps absent. Thigmokeronopsis crystallis has long midventral rows, usually 5 slightly irregular left postoral files, 1 buccal, and 8 transverse cirri. Morphogenesis is similar in both species, i.e. an anarchic field originates close to left midventral cirri and produces the opisthe's adorai membranelles, undulating membranes, and fronto-ventral-transverse (FVT) cirri; the proter's anarchic field forms near the paroral membrane and splits into primordia for undulating membranes and adorai membranelles; the FVT anlage originates independently close to the anterior left midventral cirri; all primordia form apparently de novo and all parental cirri are replaced. Reorganization resembles the development of the proter.

Divisional morphogenesis in Bakuella pampinaria nov. spec, and reevaluation of the classification of the urostylids (ciliophora, hypotrichida)

A new hypotrichous ciliare, Bakuella pampinaria nov. spec, colonizing vineleaf and pear-tree litter, is described. Bakuella pampinaria differs from the other species of the genus by having distinct rows of yellowish cortical granules. Several morphogenetic differences separate Bakuella pampinaria from Bakuella edaphoni and other congeners, especially in that the transverse cirri do not participate in the formation of the oral primordium. The type population of Pseudourostyla cristata was reinvestigated. Two frontoterminal cirri are recognizable in dividing specimens indicating that this genus is valid, i.e. different from Urostyla, which very likely lacks such cirri. The urostyline hypotrichs are recognized as a monophyletic taxon by two apomorphies, viz. the midventral cirri and the partial or complete reorganization of the proter's adorai zone of membranelies during cell division. Phylogeny and evolution within the urostylids are much less clear since character states (apomorphies, plesiomorphies, convergencies) are uncertain and morphogenetic data are still too sparse or inaccurate. This is exemplified on a selected set of genera using Hennig's phylogenetic method.

Morphologie und Morphogenese des Bodenciliaten Periholosticha wilberti nov. spec. (Ciliophora, Hypotrichida)

The morphology and morphogenesis of the soil hypotrichous ciliate Periholosticha wilberti nov. spec. from Qingdao (Tsingtao, 36°8′N, 120°43′E), P.R. China are investigated. Periholosticha wilberti differs from the other members of the genus by its bodyshape and the infraciliature. 8 stages of the cortical and nuclear fission are described and depicted. The morphogenesis starts with a proliferation of the basal bodies for the primordia (primary primordia) close by the postoral ventral cirri. The primary primordia break up during the middle stages of the morphogenesis and form secondary primordia: the anterior ones become the anlagen of life frontoventral cirri of the proter, the posterior ones become that of the opisthe. Anlage I evolves from the oral primordium in the proter, but in the opisthe it develops from the anlagencomplex of the fronto ventral cirri (primary primordia). The anlagen 1 to 3 generate 1, 1 (2), 2 frontal cirri; the frontoterminal cirri develop from the last anlage; the ventral cirri come from the one befor the last one and the rest anlagen make up the midventral cirri. During the morphogenesis there are no transversal cirri which can be identified. The overall pattern of the morphogenetic events and the infraciliature are similar to the genus Parabakuella Song & Wilbert , 1988, which has many short ventralcirrus rows. According to its morphogenesis and infraciliature the species is very characteristic for the family Urostylidae and to be considered as a true member of it. Es werden die Morphologie und Morphogenese des Bodenciliaten Periholosticha wilberti nov. spec, aus Qingdao (Tsingtao, 36°08′N; 120°43′E), Volksrepublik China untersucht. Die neue Species unterscheidet sich von den anderen bekannten Arten des Genus vor allem durch ihre Körperform und Infraciliatur. Von den bei der Morphogenese ablaufenden Veränderungen der Infraciliatur und des Kernapparates werden 8 Stadien beschrieben und abgebildet. Die Morphogenese beginnt mit der Proliferation von Basalkörpern für das Primordium dicht neben den postoralen Ventralcirren. Aus dem Primordium und den Ventralcirren entwickeln sich 8–10 Primärprimordien. Die Primärprimordien weichen in den mittleren Stadien der Morphogenese auseinander und bilden zusammen mit dem Oralprimordium die Sekundärprimordien: die vorderen werden zu den Frontoventralcirren-Anlagen des Proter, die hinteren zu jenen des Opisthen. Die Anlage I entwickelt sich beim Proter aus dem Oralprimordium, beim Opisthen dagegen aus den Frontoventralcirren-Anlagen. Aus den Anlagen I–III entstehen die Frontalcirren; aus der letzten Anlage bilden sich die Frontoterminalcirren; aus der vorletzten Anlage differenzieren sich die Ventralcirren; die restlichen Anlagen bauen die Midventralcirren auf. Während der Morphogenese entstehen keine Transversal-cirren. Die Bildungsweise der Cirren und die Infraciliatur des Genus zeigen, daß die nächst verwandte Gattung Parabakuella Song & Wilbert , 1988 ist.

Division and reorganization in the genus Psevdokeronopsis and relationships between urostylids and oxytrichids (ciliophora, hypotrichida)

Summary The cortical development of Pseudokeronopsis rubra, P. carnea , and P. flava was investigated using the protargol method. The overall pattern of the morphogenetic events is similar in all strains. In the opisthe new basal bodies originate close to several intact left midventral cirri. The primordia of the adorai membranelies (AMP), the undulating membranes (UMP), and the fronto-midventral-cirri (FMA) develop from the growing anachic field. In the proter, proliferation occurs de novo on the surface of the buccal cavity generating the AMP and UMP. The FMA originate apokinetal to the right of the parental paroral membrane. The new undulating membranes generate the first frontal cirrus. The longitudinal series of oblique streaks can be divided in three segments: (1) about 32 anterior anlagen which become frontal or midventral cirri form two cirri each; (2) the next 4–6 anlagen build three cirri, each generating pairs of midventral cirri and transverse cirri at their posteriormost ends; (3) the two posteriormost anlagen produce 4 cirri each — transverse, ventral, and frontoterminal cirri. In P. flava the posteriormost and even the anteriormost anlagen from supernumerary (if compared with the interphase cells) cirri which are resorbed later. Marginal cirral rows and dorsal kineties develop within the parental structures. The numerous macronuclear segments divide without prior fusion. Reorganization corresponds to the divisional processes of the opisthe, but only slight deformations of the macronuclear segments occur. This investigation provides ontogenetic criteria for the families Pseudokeronopsidae and Bakuellidae. The single frontal cirral arch developing from the undulating membrane primordium in the Keronidae is termed “monocorona”, whereas the “bicorona” consisting of an anterior and a posterior row of arched cirri in the frontal region of several urostylids originates, apart from the first frontal cirrus, in the same way as the midventral primordia. Several characters suggest a common ancestor of urostylids and oxytrichids. The most important synapomorphies are the frontoterminal cirri and the few ventral cirri close to the transverse cirri.