Dorsal Brush Research Articles

Identification of fourth-instar larvae of Aedes albopictus (Skuse) (Diptera: Culicidae) employing scanning electron microscopic tool.

Aedes albopictus is a vector of numerous viruses in tropical and subtropical regions worldwide, including encephalitis and dengue fever. Although the identification keys depend exclusively on the characteristics of the fourth larval instar, the studies were carried out using scanning electron microscopy (SEM) on the morphology of Ae. albopictus are still insufficient, and more research is required. Therefore, the purpose of this study was to present a comprehensive description of Ae. albopictus mosquitoes based on the morphological features of their fourth-instar larvae to distinguish them from other mosquito species. Antennae, feeding mouth brushes, mandibles, maxillae, labia, comb scales, anal papillae, siphon, respiratory spiracles, and pecten teeth were among the morphological features specifically described using SEM. The sensilla trichoidea and the sensilla basiconica are the sensory spicules found on the antennal integument. The labrum is a tessellated membrane with two movable brushes on the sides and one middle brush. The mandibles have four sellar setae on the anterolateral side, and the maxillae, which have a thumb-like structure and a palp located laterally and about four-fifths of the way from the maxillary brush base to the maxillary notch, are the articulating appendages. On the apex of the palp, there are five sensilla. The eighth abdominal segment is a tiny pentagonal structure with 12 comb scales laterally and a respiratory siphon dorsally. The siphon has two rows of pectin teeth, with 12 teeth per row. Four pairs of siphonal tufts and five perispiracular lobes surround the respiratory spiracles. The anal segment has four anal papillae, a ventral brush, a dorsal brush, and an incomplete saddle. The findings demonstrate that the fourth-instar larvae of Ae. albopictus have distinctive morphological features, which are crucial for understanding their key characteristics and identifying them, preventing inaccurate identification, and facilitating the control of diseases transmitted by the mosquito vector. RESEARCH HIGHLIGHTS: A detailed description of various taxonomical interest structures for the fourth-instar larvae of Aedes albopictus is included in this study. Scanning electron microscopy is considered a helpful technique for identifying Ae. albopictus larvae in their fourth instar.

Highly divergent morphology but a close molecular phylogenetic relationship between two little-known ciliate genera Actinobolina and Papillorhabdos (Protozoa: Ciliophora: Litostomatea) with description of two new species.

Free-living litostomatean ciliates, prominent microeukaryote predators commonly encountered in freshwater and marine habitats, play vital roles in maintaining energy flow and nutrient cycles. Nevertheless, understanding their biodiversity and phylogenetic relationships remains challenging due to insufficient morphological information and molecular data. As a new contribution to this group, three haptorian ciliates, including two new species (Actinobolina bivacuolata sp. nov. and Papillorhabdos foissneri sp. nov.) and the insufficiently described type species, Actinobolina radians, were isolated from wetlands around Lake Weishan, China and investigated by a combination of living morphology, stained preparations, and 18S rRNA gene sequence data. An illustrated key of the valid species within the two genera is provided. In addition, we reveal the phylogenetic positions of these two genera for the first time. Although they differ in all key morphologic characters such as general appearance (ellipsoidal with numerous tentacles vs. cylindrical), extrusomes (stored in tentacles vs. anchored to pellicle), circumoral kinety (present vs. absent), composition of somatic kineties (kinetosome clusters vs. monokinetids), and number of dorsal brush rows (1 vs. 4), they both cluster in a fully supported clade in the phylogenetic tree, which indicates that the biodiversity and additional molecular markers of this group need further exploration.

Enchelyothrix muria n. gen, n. sp., (Ciliophora, Litostomatea, Spathidiida), an extreme halotroph spathidiid from Maharloo Lake, Iran

Although free-living ciliated protists (Ciliophora) commonly inhabit aquatic and terrestrial biotopes of mild to moderate salinity (PSS-practical salinity scale S = 10–150), very few have adapted to life at more extreme salinities (>150 to saturation). Such extreme halophiles or halotrophs are of interest from the standpoints of evolution, cell physiology, ecology, and even astrobiology. In this work, we present the morphology, 18S rRNA gene sequence, and phylogenetic analysis of a novel spathidiid ciliate (Ciliophora, Litosatomatea) that thrives in saturated brines of Maharloo Lake, Iran. Based on its unique combination of morphologic features, its molecular characterization, and its unusual ecology, it is assigned to a newly erected monotypic genus incertae sedis in order Spathidiida. The new species differs from other spathidiids by: a cell with a very short acutely pointed tail, the absence of a circumoral kinety with, instead, inclined, interrupted circumoral kinetofragments at the anterior end of somatic kineties and brush rows abutting the oral bulge, the absence of a contractile vacuole, a heteromorphic dorsal brush comprising five or six rows, and an extreme (at or near saturation) hypersaline habitat. We briefly discuss the persistent uncertainties regarding the phylogenetic relationships within the order Spathidiida.

Taxonomic Accounts and Phylogenetic Positions of the Far East Asian Centipedes Scolopocryptops elegans and S. curtus (Chilopoda: Scolopendromorpha).

The epigean centipede genus Scolopocryptops Newport, 1844 consists of two monophyletic lineages, the "Asian/North American" and "Neotropical/Afrotropical" groups. Most of the "Asian/North American" species bear the complete sulcus/sulci along the lateral margin of the cephalic plate and sternites lacking sulci, whereas Japanese Scolopocryptops elegans (Takakuwa, 1937) bears short lateral sulci on the cephalic plate and Taiwanese Scolopocryptops curtus (Takakuwa, 1939) lacks the cephalic marginal sulci, and both species bear a longitudinal sternal sulcus. The taxonomic accounts of S. elegans and S. curtus were revisited in this study based on newly collected specimens. We found that these two species share a characteristic of the second maxilla, that they lack the transparent margin on the dorsal brush, which distinguishes them from other "Asian/North American" species. Scolopocryptops elegans and S. curtus can be distinguished from each other by the characters of their antennal articles, cephalic plate, forcipular coxosternite, tergite 23, and coxopleuron. Phylogenetic analyses using nuclear 28S ribosomal RNA and mitochondrial cytochrome c oxidase subunit I sequences confirmed that S. elegans and S. curtus are closely related and form a single clade sister to a clade comprising all the other "Asian/North American" Scolopocryptops species.

Morphology and Molecular Phylogeny of Fuscheriides baugilensis sp. nov. (Protozoa, Ciliophora, Haptorida) from South Korea

The morphology and molecular phylogeny of a new haptorid ciliate, Fuscheriides baugilensis sp. nov., discovered in a temporary pond in South Korea, were investigated. The new species is characterized by its small body size (30–55 × 15–20 μm in vivo), oblong to rod-shaped extrusomes in the oral bulge and cytoplasm, 14–16 somatic kineties, two dorsal brush rows, and single subapical ciliary condensation. The phylogenetic analyses based on the 18S rRNA gene sequences show that the family Fuscheriidae is paraphyletic and the species belong to the genera Fuscheriides and Pseudofuscheria cluster together in the same subclade, while Fuscheria is in a different subclade, suggesting that the subapical ciliary condensation characterizing the two former genera has a higher taxonomic value than the shape of extrusomes for genera separation.

Taxonomy and Phylogeny of the Dileptid Ciliate Genus Paradileptus (Protista: Ciliophora), With a Brief Review and Redescriptions of Two Species Isolated From a Wetland in Northern China.

Members of the genus Paradileptus are apex predators in microbial food webs. They are often encountered in freshwater biotopes and have been used in research on water quality monitoring and ecology. Nevertheless, our understanding of the biodiversity of Paradileptus, especially its ecological and genetic diversities, is very poor which hinders our ability to understand the ecosystem services it provides. The present study gives a detailed account of two Chinese populations of Paradileptus elephantinus and P. conicus including their living morphology, infraciliature, and molecular phylogenies based on 18S, 5.8S, and ITS ribosomal DNA sequences. The phylogenetic relationships between these two species and other rhynchostomatians are investigated. We also explore the potential contribution of differentiation of the proboscis (e.g., extrusomes, dorsal brush, and differentiated kineties) to niche partitioning and speciation in Paradileptus. The global distribution of Paradileptus is summarized based on published data. Finally, a key to the identification of the valid species of Paradileptus is provided.

Taxonomy, phylogeny, and geographical distribution of the little-known Helicoprorodon multinucleatum Dragesco, 1960 (Ciliophora, Haptorida) and key to species within the genus

A little-known haptorid ciliate, Helicoprorodon multinucleatum Dragesco, 1960, was found in a sandy beach at Qingdao, China. Its morphology was studied based on microscopic observations of live and protargol-stained specimens and morphometrics, and the phylogeny was analyzed using SSU rRNA gene sequences. Helicoprorodon multinucleatum is characterized by the combination of the following features: (i) a very narrowly worm-like body with a size of about 300–1500 μm × 30–60 μm in vivo, and two circles of horn-like protuberances around the head; (ii) 50–160 spherical macronuclear nodules scattered throughout the body; (iii) rod-shaped, 10–50 μm long extrusomes gathered into several bunches, which are randomly distributed beneath pellicle; and (iv) 42–88 somatic kineties, including four oralized kineties and two dorsal brush rows. Phylogenetic analyses reveal that both the family Helicoprorodontidae and the genus Helicoprorodon might be monophyletic. In addition, we provide an illustrated key to the species and the geographical distribution of the genus Helicoprorodon.

Morphological and molecular phylogeny of the polycytopharyngeal ciliate Pycnothrix monocystoides Schubotz, 1908

We reinvestigated Pycnothrix monocystoides Schubotz, 1908 from the intestine of the African Rock Hyrax (Procavia capensis) collected from Saudi Arabia, using protargol impregnation and electron microscopy. Pycnothrix is a unique, up to 5 mm long intestinal ciliate with about two million cilia and many cytostomes (i.e. actual cytostome plus cytopharynx; polycytopharyngy) in the oral furrow (∼vestibulum) that extends on both sides of the cell. Both walls of the furrow are covered by adoral membranelle-like ciliary polymerizations. To the right of the furrow and the cytostomes there are small ciliary fields, very likely homologous to the “dorsal brush” found in free-living litostomateans. The molecular investigations show Pycnothrix as sister to Balantidium and endemic Australian intestinal ciliates, e.g. the genus Bandia. We propose that the common ancestor had both an oral furrow and a special ciliary field both similar to that found in Balantidium. The unique morphology (polycytopharyngy) and the rather distinct molecular separation suggest maintenance of the family status given by Poche (1913).

Morphology and phylogeny of Apertospathula oktemae n. sp. (Ciliophora, Haptoria, Spathidiida) from Lake Van, Turkey

A new spathidiid ciliate, Apertospathula oktemae n. sp., was isolated from bottom sediments on the eastern shore of Lake Van, Turkey. The living cells are clavate and 45–80 × 17–30 μm in size. This species is characterized by a lasso-shaped circumoral kinety composed of more than 100 dikinetids, 16 meridionally arranged somatic ciliary rows, a three-rowed dorsal brush with 1.5–2.0 μm long bristles, an oblong and curved macronucleus with an ellipsoidal or globular micronucleus, numerous refractive granules in the anterior portion of the cell, and a single posterior contractile vacuole. This new species lives in alkaline brackish water. Apertospathula oktemae differs from congeners by their body shape, number of oral dikinetids, presence of refractive granules, and their habitat. This is the first study to investigate the 18S rRNA gene sequence of a member of the genus Apertospathula. Phylogenetic trees show that Apertospathula oktemae is most closely related to Arcuospathidium sp. There is a discrepancy between the morphological classification system of the spathidiid ciliates and their molecular phylogeny. To overcome this problem, more molecular data, obtained from more taxa from various geographical regions of the world, are needed.

Diversification dynamics of rhynchostomatian ciliates: the impact of seven intrinsic traits on speciation and extinction in a microbial group

Ciliates are a suitable microbial model to investigate trait-dependent diversification because of their comparatively complex morphology and high diversity. We examined the impact of seven intrinsic traits on speciation, extinction, and net-diversification of rhynchostomatians, a group of comparatively large, predatory ciliates with proboscis carrying a dorsal brush (sensoric structure) and toxicysts (organelles used to kill the prey). Bayesian estimates under the binary-state speciation and extinction model indicate that two types of extrusomes and two-rowed dorsal brush raise diversification through decreasing extinction. On the other hand, the higher number of contractile vacuoles and their dorsal location likely increase diversification via elevating speciation rate. Particular nuclear characteristics, however, do not significantly differ in their diversification rates and hence lineages with various macronuclear patterns and number of micronuclei have similar probabilities to generate new species. Likelihood-based quantitative state diversification analyses suggest that rhynchostomatians conform to Cope’s rule in that their diversity linearly grows with increasing body length and relative length of the proboscis. Comparison with other litostomatean ciliates indicates that rhynchostomatians are not among the cladogenically most successful lineages and their survival over several hundred million years could be associated with their comparatively large and complex bodies that reduce the risk of extinction.

Evaluation of Systematic Position of Helicoprorodontids and Chaeneids (Ciliophora, Litostomatea): An Attempt to Break Long Branches in 18S rRNA Gene Phylogenies.

Phylogenetic position of some free-living litostomatean taxa has not been correctly determined because of long-branch artifacts in 18S rRNA gene trees. The main aim of this study was to test the effectiveness of various masking algorithms, tree-building techniques, binarization of DNA data as well as combining morphological and molecular data to eliminate long-branch attraction of two problematic groups, helicoprorodontids and chaeneids. Guidance and SlowFaster masking in a combination with PhyloBayesian tree construction erased the artifactual positions of helicoprorodontids and chaeneids. On the other hand, binarization of DNA sequences and the strategy of combining morphological and molecular data eliminated only the artifactual position of chaeneids but not that of helicoprorodontids which were still being attracted by out-group taxa. According to statistical tree topology tests and comparative morphological studies, helicoprorodontids are classified as a distinct order while chaeneids are considered to be fast evolving members of the order Lacrymariida. The high body contractility, "cephalization" of the anterior body end, and helicalization of the anterior portion of some or all somatic ciliary rows indicate relatedness of helicoprorodontids, chaeneids, and lacrymariids. On the other hand, the dorsal brush separated from the circumoral kinety by dense ciliary files supports kinships of chaeneids, lacrymariids, and didiniids.

Constraints on Phylogenetic Interrelationships among Four Free-living Litostomatean Lineages Inferred from 18S rRNA gene-ITS Region sequences and Secondary Structure of the ITS2 molecule

We investigated interrelationships between four free-living litostomatean lineages, using 18S rRNA gene and ITS region sequences as well as the secondary structure of the ITS2 molecules. Our phylogenetic analyses confirmed the deep split of free-living litostomateans into Rhynchostomatia and Haptoria represented here by Haptorida, Pleurostomatida, and Spathidiida. This bifurcation is also corroborated by the signature of the rhynchostomatian and haptorian ITS2 molecules. Specifically, the consensus stems of helices II and III are longer by one base pair in Rhynchostomatia, while the terminal loops of both helices are longer by one or two nucleotide/-s in Haptoria. A close relationship of Pleurostomatida and Haptorida is favored by quartet likelihood-mapping and supported by a 5’-AG vs. CU-3’ motif in the variable part of helix II and by two morphological apomorphies, i.e., meridionally extending somatic kineties and a non-three-rowed dorsal brush. Although monophyletic origin of Spathidiida is poorly supported in phylogenetic trees, the unique motif 5’-GA vs. UC-3’ present in the consensus helix II stem could be an important molecular synapomorphy of spathidiids, apart from the ancestrally anteriorly curved somatic kineties and the three-rowed dorsal brush. The peculiar family Pseudoholophryidae has very likely found its phylogenetic home among spathidiids, as an early branching lineage.

New contributions to the biodiversity of ciliates (Protozoa, Ciliophora) from Antarctica, including a description of Gastronauta multistriata nov. spec.

Antarctica is a remote and isolated biotope which makes it an ideal location for studying new and endemic species. Since there is little literature available on the diversity of ciliates in this area, a taxonomic survey of ciliates from melt-water of Collins glacier, King George Island, was carried out from January to March 2006. As a result, the morphology and infraciliature of five ciliates, including one new species, are described using live observations and silver staining: Gastronauta multistriata nov. spec., Neokeronopsis asiatica Foissner et al., 2010, Paraholosticha muscicola Kahl, 1932, Oxytricha sp., and Cyclidium glaucoma Muller, 1786. Gastronauta multistriata nov. spec. is distinguished from its congeners by the following combination of characters: cell size in vivo on average 80 × 40 μm; 5–9 kineties in left ciliary field; 18–23 kineties in right ciliary field, including 10–12 postoral kineties; 7–10 preoral kineties; dorsal brush along anterior dorsal margin, consisting of 5–8 groups of basal bodies. The only minor differences between the current population of N. asiatica and a previously described Antarctic population are the numbers of caudal cirri (6–10 vs. 8–15) and dorsal kineties (11–13 vs. 12–18). Paraholosticha sterkii is synonymised with P. muscicola. The Antarctic population of C. glaucoma corresponds well with a former population from China, the only difference being the number of kinetids in SK n (11–17 vs. 9–11). This work will contribute to the understanding of ciliate diversity in this little studied area.

Morphology of Two Novel Species of Chaenea (Ciliophora, Litostomatea): Chaenea paucistriata spec. nov. and C. sinica spec. nov.

During faunistic studies of ciliates in coastal waters of Daya Bay and Bohai Bay, China, two previously unknown ciliates were discovered and investigated using standard taxonomic methods. Morphological comparative analyses revealed that they represent two novel species in the genus Chaenea. Chaenea paucistriata spec. nov. can be distinguished from its congeners by the following traits: body length in vivo about 180–250 µm; eight somatic kineties; dorsal brush rows 1–4 consisting of three, five, seven, and two dikinetids, respectively; rod-like extrusomes, 8 µm long; 63–94 macronuclei; cortical granules minute and colourless. Chaenea sinica spec. nov. differs from its congeners in having: body length in vivo about 140–240 µm; 17–21 somatic kineties; dorsal brush rows 1–4 consisting of 3–7, 10 or 11, 11–13, and 3–6 dikinetids, respectively; rod-like extrusomes about 6–8 µm long; 71–164 macronuclei. A key is presented to assist the identification of all Chaenea species.

Morphology, ciliary pattern and molecular phylogeny of Trachelophyllum brachypharynx Levander, 1894 (Litostomatea, Haptoria, Spathidiida)

We isolated a relatively unknown haptorian ciliate, Trachelophyllum brachypharynx , in brackish water from the mouth of the Taehwa River, South Korea. The morphology of this isolate was studied using in vivo observation and protargol impregnation, and its evolutionary history was revealed by phylogenetic analysis of the 18S rRNA gene. The main features of T. brachypharynx include (i) a very narrowly fusiform and slightly contractile body about 380 × 40 μm in size; (ii) two ellipsoidal macronuclear nodules typically connected by a fine strand; (iii) a single terminal contractile vacuole; (iv) filiform extrusomes that are typically 30 µm long; (v) an average of 24 ciliary rows, with two of them anteriorly differentiated into an isostichad dikinetidal dorsal brush; and (vi) hat-shaped lepidosomes. Based on the 18S rRNA gene phylogeny, T. brachypharynx clustered together with Trachelophyllum sp. within the order Spathidiida. Furthermore, phylogenetic trees and networks indicate some members from the genera Enchelyodon and Spathidium as the nearest relatives of trachelophyllids. Therefore, based on the present molecular and comparative-morphological analyses, we suggested a hypothesis explaining how trachelophyllids may have evolved from a spathidiid-like ancestor via an enchelyodonid-like stage.

Molecular phylogenetic lineage of Plagiopogon and Askenasia (Protozoa, Ciliophora) revealed by their gene sequences

Prostomates and haptorians are two basal groups of ciliates with limited morphological characteristics available for taxonomy. Morphologically, the structures used to identify prostomates and haptorians are similar or even identical, which generate heavy taxonomic and phylogenetic confusion. In present work, phylogenetic positions lineage of two rare genera, Plagiopogon and Askenasia, were investigated. Three genes including small subunit ribosomal RNA gene (hereafter SSU rDNA), internal transcribed spacer region (ITS region), and large subunit ribosomal RNA gene (LSU rDNA) were analyzed, 10 new sequences five species each. Our findings included 1) class Prostomatea and order Haptorida are multiphyletic; 2) it may not be appropriate to place order Cyclotrichiida in subclass Haptoria, and the systematic lineage of order Cyclotrichiida needs to be verified further; 3) genus Plagiopogon branches consistently within a clade covering most prostomes and is basal of clade Colepidae, implying its close lineage to Prostomatea; and 4) Askenasia is phylogenetically distant from the subclass Haptoria but close to classes Prostomatea, Plagiopylea and Oligohymenophorea. We supposed that the toxicyst of Askenasia may be close to taxa of prostomes instead of haptorians, and the dorsal brush is a more typical morphological characteristics of haptorians than toxicysts.

Reconciling morphological and molecular classification of predatory ciliates: Evolutionary taxonomy of dileptids (Ciliophora, Litostomatea, Rhynchostomatia)

The order Dileptida is a small group of predatory ciliates characterized by a proboscis serving for prey capture. Although monophyly of the order is strongly supported, generic relationships between dileptid taxa were left mostly unresolved in 18S rRNA gene phylogenies. To overcome this problem, we applied the synergistic effect of combining multiple molecular markers with morphological data. Furthermore, we inferred dileptid evolutionary history by a multifaceted analysis strategy, including tree-building methods, phylogenetic networks, split spectrum analysis, quartet likelihood mapping, and reconstruction of ancestral morphologies. This complex approach revealed: (1) monophyly of the families Dimacrocaryonidae and Dileptidae; (2) polyphyly of Microdileptus, Pseudomonilicaryon, and Rimaleptus; and (3) homoplastic nature of several generic diagnostic features, viz., macronuclear pattern, size of oral bulge opening, and orientation of preoral kineties. Controversies in the internal phylogeny of the family Dimacrocaryonidae could be elucidated after reconstruction of ancestral morphologies at deeper nodes of phylogenetic trees in a combination with budding evolutionary processes. Moreover, we solved the “Rimaleptus” dilemma by splitting the family Dimacrocaryonidae into two new subfamilies, the Dimacrocaryoninae with two-rowed dorsal brush and the Rimaleptinae with multi-rowed brush as well as by establishing a new genus, Rurikoplites, from whose species several dimacrocaryonid genera very likely evolved by budding.

Morphological and molecular characterization of the name-bearing type species Rimaleptus binucleatus (Kahl, 1931), with a phylogenetic re-analysis of dileptid evolutionary history (Ciliophora: Litostomatea: Rhynchostomatia)

We collected Rimaleptus binucleatus from soil in the surroundings of the town of Ulsan, South Korea. Its morphology and 18S rRNA gene were studied using standard methods. This possibly widely distributed species is characterized by: (i) a size of about 170–400×20–65μm; (ii) a narrowly to cylindrically dileptid body with proboscis occupying about 30–65% of body length; (iii) two dorsal contractile vacuoles; (iv) two size groups of rod-shaped extrusomes; and (v) about 18–29 ciliary rows, 4–6 of them anteriorly differentiated into a staggered dorsal brush. Phylogenetic analyses of five new rhynchostomatian 18S rRNA gene sequences supported monophylies of the orders Tracheliida and Dileptida, but revealed that the genera Rimaleptus and Pseudomonilicaryon are polyphyletic. Monophyly of genera with two macronuclear nodules was consistently rejected, but monophylies of dileptids with many scattered macronuclear nodules and of dileptids with moniliform macronucleus and multi-rowed dorsal brush could not be excluded by statistical topology tests. Nevertheless, phylogenetic network analyses indicated considerable conflict in the phylogenetic signal provided by the 18S rRNA gene to resolve unambiguously relationships among dileptid genera.

Five New Spathidiids (Ciliophora: Haptoria) from Caribbean Tank Bromeliads

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 mu m long vs. rod-shaped and > 15 mu m 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 x 25 mu m vs. 240 x 17 mu m), 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.

Morphological and molecular characterization of Parafurgasonia zhangi spec. nov. and Chilodonella acuta Kahl, 1931 (Protozoa, Ciliophora), from a soil habitat of Saudi Arabia.

The morphology and infraciliature of two soil ciliates, Parafurgasonia zhangi spec. nov. and Chilodonella acuta Kahl, 1931, collected from Saudi Arabia, were investigated by observations of both living cells and specimens after standard staining methods. P. zhangi differs from its congeners by the combination of the following features: excretory pore quite near posterior end of paroral membrane, 16 or 17 somatic kineties with about 11 kinetids in each one on dorsal side, paroral membrane gently curved and composed of about 15 dikinetids, and hypostomial organelle composed of four or five files of kinetids with four monokinetids each. The diagnosis of Chilodonella acuta was renewed to include characteristics revealed by the silver impregnation method: cells in vivo measuring 33-45) × 18-26) µm, dorsal hump and tail-like podite present, two contractile vacuoles, seven left and five right kineties, 9-11 nematodesmal rods, and dorsal brush containing about 11 basal bodies. Phylogenetic analyses based on small-subunit rRNA gene sequences showed that P. zhangi was closer to species of the Colpodidiidae rather than the Furgasoniidae represented by Furgasonia blochmanni, and Chilodonella acuta clustered with its congener Chilodonella uncinata but was a well-outlined species of the genus.