Ultrastructural description of Breviata anathema, n. gen., n. sp., the organism previously studied as "Mastigamoeba invertens"

An understanding of large-scale eukaryotic evolution is beginning to crystallise, as molecular and morphological data demonstrate that eukaryotes fall into six major groups. However, there are several taxa of which the affinities are yet to be resolved, and for which there are only either molecular or morphological data. One of these is the amoeboid flagellate Mastigamoeba invertens. This organism was originally misidentified and studied as a pelobiont using molecular data. We present its first light microscopical and ultrastructural characterisation. We demonstrate that it does not show affinities to the amoebozoan pelobionts, because unlike the pelobionts, it has a double basal body and two flagellar roots, a classical Golgi stack, and a large branching double membrane-bound organelle. Phylogenetic analyses of small subunit ribosomal RNA suggest an affinity with the apusomonads, when a covariotide correction for rate heterogeneity is used. We suggest that previous molecular results have been subject to artefacts from an insufficient correction for rate heterogeneity. We propose a new name for the taxon, Breviata anathema; and the unranked, apomorphy-based name "Breviates" for Breviata and its close relatives.     

A description of seven Antarctic marine gymnamoebae including a new subspecies, two new species and a new genus: Neoparamoeba aestuarina antarctica n. subsp., Platyamoeba oblongata n. sp., Platyamoeba contorta n. sp. and Vermistella antarctica n. gen. n. sp

Seven marine gymnamoebae were isolated from different environments of seawater, slush (pack ice meltwater), and sediment in the Ross Sea area of Antarctica. All amoebae were isolated and maintained at temperatures below 4 degrees C. Growth, rate of locomotion, and general morphology were observed at an environmentally appropriate temperature (1 degrees C) and at room temperature (approximately 25 degrees C). Molecular (srDNA sequences) and microscopical techniques were used to identify the gymnamoebae and establish their phylogenetic affinities. Three isolates (S-131-2, SL-200, and W4-3) were assigned to a psychrophilic subspecies of Neoparamoeba aestuarina, N. aestuarina antarctica n. subsp., one isolate (S-205) was assigned to a new species of Platyamoeba, P. oblongata n. sp., two isolates (W51C#4 & W51C#5) were also assigned to a new species of Platyamoeba, P. contorta n. sp., and one isolate (S-241) was a novel psychrophilic gymnamoeba Vermistella antarctica n. gen. n. sp. Molecular and morphological results revealed that V. antarctica was not related to any described family of gymnamoebae. Strains S-205, W51C#4, and W51C#5 were capable of locomotion at room temperature, while strains SL-200, S-131-2, W4-3, and S-241 exhibited locomotion only below approximately 10 degrees C. Our results imply that the Antarctic environment is host both to cosmopolitan gymnamoebae that have acquired adaptations for existence at low environmental temperature and to apparently novel psychrophilic amoebae described here for the first time.     

Gyrodiniellum shiwhaense n. gen., n. sp., a new planktonic heterotrophic dinoflagellate from the coastal waters of western Korea: morphology and ribosomal DNA gene sequence

The heterotrophic dinoflagellate Gyrodiniellum shiwhaense n. gen., n. sp. is described from live cells and from cells prepared for light, scanning electron, and transmission electron microscopy. Also, sequences of the small subunit (SSU) and large subunit (LSU) of rDNA have been analyzed. The episome is conical, while the hyposome is ellipsoid. Cells are covered with polygonal amphiesmal vesicles arranged in 16 horizontal rows. Unlike other Gyrodinium-like dinoflagellates, the apical end of the cell shows a loop-shaped row of five elongate amphiesmal vesicles. The cingulum is displaced by 0.3-0.5 × cell length. Cells that were feeding on the dinoflagellate Amphidinium carterae Hulburt were 9.1-21.6 μm long and 6.6-15.7 μm wide. Cells of G. shiwhaense contain nematocysts, trichocysts, a peduncle, and pusule systems, but they lack chloroplasts. The SSU rDNA sequence is >3% different from that of the six most closely related species: Warnowia sp. (FJ947040), Lepidodinium viride Watanabe, Suda, Inouye, Sawaguchi & Chihara, Gymnodinium aureolum (Hulburt) Hansen, Gymnodinium catenatum Graham, Nematodinium sp. (FJ947039), and Gymnodinium sp. MUCC284 (AF022196), while the LSU rDNA is 11-12% different from that of Warnowia sp., G. aureolum, and Nematodinium sp. (FJ947041). The phylogenetic trees show that the species belongs in the Gymnodinium sensu stricto clade. However, in contrast to Gymnodinium spp., cells lack nuclear envelope chambers and a nuclear fibrous connective. Unlike Polykrikos spp., cells of which possess a taeniocyst-nematocyst complex, G. shiwhaense has nematocysts but lacks taeniocysts. It differs from Paragymnodinium shiwhaense Kang, Jeong, Moestrup & Shin by possessing nematocysts with stylets and filaments. Gyrodiniellum shiwhaense n. gen., n. sp. furthermore lacks ocelloids, in contrast to Warnowia spp., Nematodinium spp., and Proterythropsis spp. Based on morphological and molecular data, we suggest that the taxon represents a new species within a new genus.     

Description of Rhynchopus euleeides n. sp. (Diplonemea), a free-living marine euglenozoan

We describe Rhynchopus euleeides n. sp., using light and electron microscopy. This free-living flagellate, which was isolated earlier from a marine habitat, can be grown axenically in a rich medium based on modified seawater. In the trophic stage, cells are predominantly elliptical and laterally flattened, but frequently change their shape (metaboly). Gliding is the predominant manner of locomotion. The two flagella, which are typically concealed in their pocket, are short stubs of unequal length, have conventional axonemes, but apparently lack a paraxonemal rod. Swarmer cells, which form only occasionally, are smaller in size and carry two conspicuous flagella of more than 2 times the body length. Cells are decorated with a prominent apical papillum. Both the flagellar pocket and the adjacent feeding apparatus seem to merge together into a single sub-apical opening. The mitochondrion, which is most likely single, is located peripherally. It is reticulated in shape and contains only a few lamellar cristae. Mitochondrial DNA is abundant and evenly distributed throughout the organelle. Morphological synapomorphies confirm the affiliation of the species with the genus Rhynchopus (Diplonemea, Euglenozoa). We discuss the characters that distinguish Rhynchopus from Diplonema corroborating the validity of the two genera.     

Parastrombidinopsis shimi n. gen., n. sp. (Ciliophora: Choreotrichia) from the coastal waters of Korea: morphology and small subunit ribosomal DNA sequence

The planktonic ciliate Parastrombidinopsis shimi n. gen., n. sp. is described from both living cells and quantitative protargol-stained (QPS) preparations and the sequence of the small subunit rDNA (SSU rDNA) is reported. This species is almost oval when the cells are alive; when stained, it is cylindrical for the upper two-fifths, half-bowl shaped for the middle two-fifths, and narrow rodshaped for the lower one-fifth. The ranges (and mean +/- standard deviation, n = 20) of cell length, cell width, and oral diameter of living cells were 112-221 microm (168 +/- 39), 88-176 microm (121 +/- 30), and 53-110 microm (80 +/- 14), respectively, while those of the QPS-stained specimens (n = 54) were 88-225 microm (162 +/- 29), 55-163 microm (102 +/- 19), and 53-98 microm (69 +/- 9), respectively. Thirty-six to 48 external oral polykinetids had cilia 25-40 microm long. However, unlike Strombidinopsis species sensu stricto, P. shimi has an external oral polykinetid zone that is an open circle. This species has two shorter polykinetids associated with the end of the oral polykinetid zone, deep in the oral cavity. Like Strombidinopsis species in the subclass Choreotrichia, 36-50 somatic kineties were equally spaced around the cell body and extended from the oral to the posterior regions with 68-105 dikinetids per kinety. Both kinetosomes of each kinetid bore cilia 3-10 microm long. Parastrombidinopsis shimi had 2 (1-4) ovoid macronuclei of 20-82 x 15-32 microm. When properly aligned, the sequence of the SSU rDNA of P. shimi (GenBank Accession No. AJ786648) was approximately 5% different from that of Strobilidium caudatum and 6% different from that of two Strombidinopsis species. Based both on morphology and gene sequence divergence, we establish this is as a new species in a new genus belonging to the family Strombidinopsidae.     

Glossomastix chrysoplasta n. gen., n. sp. (Pinguiophyceae), a new coccoidal, colony-forming golden alga from southern Australia

Glossomastix chrysoplasta gen. et sp. nov. is described from cultures isolated from sandstone rubble, Sorrento Back Beach, Mornington Peninsula, Victoria, Australia. The alga forms wall‐less, coccoidal vegetative cells that congregate in mucilaginous colonies and reproduce by successive bipartition. Plastids have girdle lamellae and partially embedded pyrenoids that are traversed by cytoplasmic channels. Zoospores are uniflagellate and swim poorly; a narrow lingulate pseudopod provides their primary form of motion. The single flagellum, which lacks hairs, a flagellar swelling, and autofluorescence, is the equivalent of the posterior flagellum in other golden algae. The anterior flagellum is absent; the basal body with which it would normally be associated is blind. The flagellar apparatus has two basal bodies, three microtubular roots, and a rhizoplast. The posterior (elder) basal body has a transitional helix that is proximal to the basal plate. Glossomastix chrysoplasta, placed in the Pinguiophyceae on the basis of molecular sequence and biochemical data, shares some ultrastructural features with other members of the class, especially Polypodochrysis teissieri, which has similar zoospores, but it also differs from other pinguiophytes in many respects. Glossomastix chrysoplasta is the pinguiophyte with, on average, the largest cells (exclusive of external materials), and it is the only one with a colonial habit.     

Haramonas dimorpha gen. et sp. nov. (Raphidophyceae), a new marine raphidophyte from Australian mangrove*

A new raphidophyte flagellate is described from the river mouth of the Daintree River, north-east Australia where there are extensive mangrove forests. The organism has two distinct phases: a club-shaped motile form, and a more or less spherical benthic non-motile form. The motile cell is metabolic and possesses 10–20 chloroplasts. The chloroplasts are imbricated, somewhat reminiscent of roofing tiles. A unique structure has been found at the posterior end of the cell. It is a tubular invagination, which consists of a single membrane supported by many small flattened vesicles. In addition, the structure is surrounded by many fibril-containing vesicles. The tubular invagination is different from both the contractile vacuoles and the pusules of dinoflagellates in both behavior and structure. Based on the possession of these unique features, it is concluded that the this mangrove flagellate should be described as a new species in a new genus and the name Haramonas dimorpha Horiguchi gen. et sp. nov. is proposed.     

Characterization of Selenaion koniopes n. gen., n. sp., an Amoeba that Represents a New Major Lineage within Heterolobosea,Isolated from the Wieliczka Salt Mine

A new heterolobosean amoeba, Selenaion koniopes n. gen., n. sp., was isolated from 73‰ saline water in the Wieliczka salt mine, Poland. The amoeba had eruptive pseudopodia, a prominent uroid, and a nucleus without central nucleolus. Cysts had multiple crater‐like pore plugs. No flagellates were observed. Transmission electron microscopy revealed several typical heterolobosean features: flattened mitochondrial cristae, mitochondria associated with endoplasmic reticulum, and an absence of obvious Golgi dictyosomes. Two types of larger and smaller granules were sometimes abundant in the cytoplasm—these may be involved in cyst formation. Mature cysts had a fibrous endocyst that could be thick, plus an ectocyst that was covered with small granules. Pore plugs had a flattened dome shape, were bipartite, and penetrated only the endocyst. Phylogenies based on the 18S rRNA gene and the presence of 18S rRNA helix 17_1 strongly confirmed assignment to Heterolobosea. The organism was not closely related to any described genus, and instead formed the deepest branch within the Heterolobosea clade after Pharyngomonas, with support for this deep‐branching position being moderate (i.e. maximum likelihood bootstrap support—67%; posterior probability—0.98). Cells grew at 15–150‰ salinity. Thus, S. koniopes is a halotolerant, probably moderately halophilic heterolobosean, with a potentially pivotal evolutionary position within this large eukaryote group.     

Andalucia (n. gen.)--the deepest branch within jakobids (Jakobida; Excavata), based on morphological and molecular study of a new flagellate from soil

A new heterotrophic flagellate (Andalucia godoyi n. gen. n. sp.) is described from soil. Earlier preliminary 18S rRNA analyses had indicated a relationship with the phylogenetically difficult-to-place jakobid Jakoba incarcerata. Andalucia godoyi is a small (3-5 mum) biflagellated cell with a ventral feeding groove. It has tubular mitochondrial cristae. There are two major microtubular roots (R1, R2) and a singlet root associated with basal body 1 (posterior). The microtubular root R1 is associated with non-microtubular fibres "I,"B," and "A," and divides in two parts, while R2 is associated with a "C" fibre. These structures support the anterior portion of the groove. Several features of A. godoyi are characteristic of jakobids: (i) there is a single dorsal vane on flagellum 2; (ii) the C fibre has the jakobid multilaminate substructure; (iii) the dorsal fan of microtubules originates in very close association with basal body 2; and (iv) there is no "R4" microtubular root associated with basal body 2. Morphological analyses incorporating the A. godoyi data strongly support the monophyly of all jakobids. Our 18S rRNA phylogenies place A. godoyi and J. incarcerata as a strong clade, which falls separately from other jakobids. Statistical tests do not reject jakobid monophyly, but a specific relationship between Jakoba libera and J. incarcerata and/or A. godoyi is rejected. Therefore, we have established a new genus Andalucia n. gen. with the type species Andalucia godoyi n. sp., and transfer Jakoba incarcerata to Andalucia as Andalucia incarcerata n. comb.     

Trochonerilla mobilis gen. et sp.n., a meiofaunal nerillid (Annelida, Polychaeta) from a marine aquarium in Moscow

A nerillid species new to science is described from the marine aquarium system of Moscow Zoo. Trochonerilla mobilis gen. et sp.n. is characterized by eight chaetigerous segments, three antennae, absence of palps, parapodia with two bundles of simple chaetae and pygidium with two anal cirri. In contrast to other eight-segmented nerillids, Trochonerilla mobilis are very active and mobile animals. They are also able to swim through the water column by means of the strong ring of cilia on the first chaetigerous segment. Their geographical origin is unknown.     

Leptojacobus dorci n. gen., n. sp. (Nematoda: Diplogastridae), an Associate of Dorcus Stag Beetles (Coleoptera: Lucanidae)

A new species of diplogastrid nematode, Leptojacobus dorci n. gen., n. sp., was isolated from adults of the stag beetle Dorcus ritsemae (Coleoptera: Lucanidae) that were purchased from a pet shop in Japan. Leptojacobus n. gen. is circumscribed by a very thin, delicate body and by a small stoma with minute armature. A combination of other stomatal characters, namely the division of the cheilostom into adradial plates, the symmetry of the subventral stegostomatal sectors, and the presence of a thin, conical dorsal tooth, further distinguishes Leptojacobus n. gen. from other genera of Diplogastridae. Phylogenetic analysis of nearly full-length SSU rRNA sequences support the new species, together with an isolate identified previously as Koerneria luziae, to be excluded from a clade including all other molecularly characterized diplogastrids with teeth and stomatal dimorphism. Therefore, the new species will be of importance for reconstruction of ancestral character histories in Diplogastridae, a family circumscribed by a suite of feeding-related novelties.     

Chromonema heliothidis n. gen., n. sp. (Steinernematidae,Nematoda), a Parasite of Heliothis zea (Noctuidae,Lepidoptera), and Other Insects

Chromonema heliothidis n. gen., n. sp. is described as an entomophilic nematode of Heliothis zea and other lepidopterous larvae; the diagnosis of the family Steinernermatidae is emended. In most morphological and host-parasite features, this nematode is similar to neoaplectanid nematodes; however, males are different in having a peloderan bursa and straight to slightly curved spicules. Although the infective-stage juveniles only give rise to hermaphrodites, the nematode is heterogonic, with both males and females being produced in the second generation. Parasitized hosts are brick-red in color and luminescent in the dark because of the association of a chromogenic, bioluminescent bacterium with the nematode. The nematode is capable of parasitizing a wide range of insects with lepidopterous larvae being most susceptible.     

Light Microscopic Observations, Ultrastructure, and Molecular Phylogeny of Hicanonectes teleskopos n. g., n. sp., a Deep-Branching Relative of Diplomonads

ABSTRACT. We describe Hicanonectes teleskopos n. g., n. sp., a heterotrophic flagellate isolated from low-oxygen marine sediment. Hicanonectes teleskopos has a ventral groove and two unequal flagella, and rapidly rotates during swimming. At the ultrastructural level H. teleskopos is a "typical excavate": it displays flagellar vanes, a split right microtubular root, "I,""B," and "C" fibres, a singlet microtubular root, and a possible composite fibre. Small subunit rRNA (SSU rRNA) gene phylogenies and an "arched" B fibre demonstrate that H. teleskopos belongs to Fornicata (i.e. diplomonads, retortamonads, and relatives). It forms a clade with the deep-branching fornicate Carpediemonas , with moderate-to-strong bootstrap support, although their SSU rRNA gene sequences are quite dissimilar. Hicanonectes differs from Carpediemonas in cell shape, swimming behaviour, number of basal bodies (i.e. 4 vs. 3), number of flagellar vanes (i.e. 2 vs. 3), anterior root organization, and by having a cytopharynx. Like Carpediemonas and Dysnectes, Hicanonectes has conspicuous mitochondrion-like organelles that lack cristae and superficially resemble the hydrogenosomes of parabasalids, rather than the mitosomes of their closer relatives the diplomonads (e.g. Giardia ).     

Tunicothrix rostrata n. g., n. sp., a new urostylid ciliate (Ciliophora, Stichotrichia) from the Yellow Sea

The morphology and infraciliature of a new ciliate, Tunicothrix rostrata n. g., n. sp., isolated from the Yellow Sea, are investigated using live observation and protargol impregnation. Tunicothrix rostrata measures about 160 x 40 mum in vivo, and has a frontal beak-like protrusion, a conspicuous cortical alveolar layer, two right marginal rows, and usually three distinct midventral pairs. The discovery of T. rostrata enables us to reconsider the classification of Erniella wilberti, a curious ciliate with obscure midventral pairs. Both species are highly similar in overall appearance and nuclear and ciliary pattern. Thus, they are united in a new genus of the family Urostylidae, Tunicothrix, and E. wilberti is transferred to Tunicothrix: Tunicothrix wilbertiLin and Song, 2004 n. comb. By contrast, Erniella filiformis, type species of Erniella, has several ventral rows and does not belong to the urostylids. Tunicothrix rostrata is easily distinguished from T. wilberti by its beak-like anterior protrusion and by the distinctly elongated right marginal row 2, which curves anteriorly on the dorsal side of the cells. Tunicothrix is closely related to Parabirojimia, differing by the invariably two (vs. five-eight) right marginal rows and the conspicuous (vs. ordinary) alveolar layer, a unique feature in urostylid ciliates.     

Morphology and gene sequence of Levicoleps biwae n. gen., n. sp. (Ciliophora, Prostomatida), a proposed endemic from the ancient Lake Biwa, Japan

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.     

Inanidrilus bulbosus gen. et sp.n., a Marine Tubificid (Oligochaeta) from Florida, USA

Inanidrilus bulbosus gen. et sp.n. is described from subtidal sands near Miami, Florida. The species lacks alimentary canal, but it possesses highly modified penial setae and an unpaired dorsal spermatheca. It appears closely related to Phallodrilus Pierantoni, but since it is devoid of anterior prostate glands, which are attached to the ental ends of the atria in Phallodrilus , a new monotypic genus, Inanidrilus gen.n., is established.