First report of epiphytic dinoflagellate Coolia malayensis (Dinophyceae) in the southeastern Pacific Ocean

Coolia species are epiphytic and benthic dinoflagellates with a cosmopolitan distribution in tropical and subtropical areas. In the austral summer of 2016, during a survey in Bahía Calderilla, a dinoflagellate of the genus Coolia was detected in macroalgae samples, and a clonal culture was established. Subsequently, the cultured cells were observed by scanning electron microscopy (SEM) and identified as C. malayensis based on their morphological characteristics. Phylogenetic analyses based on the LSU rDNA D1/D2 regions confirmed that strain D005-1 corresponded to C. malayensis and clustered with strains isolated from New Zealand, Mexico, and Asia Pacific countries. Although the strain D005-1 culture did not contain yessotoxin (YTX), cooliatoxin, 44-methyl gambierone, or its analogs in detectable amounts by LC–MS/MS, more research is needed to evaluate its toxicity and to determine the possible impact of C. malayensis in northern Chilean waters.     

Concatenated SSU and LSU rDNA data confirm the main evolutionary trends within myxosporeans (Myxozoa: Myxosporea) and provide an effective tool for their molecular phylogenetics

Views on myxosporean phylogeny and systematics have recently undergone substantial changes resulting from analyses of SSU rDNA. Here, we further investigate the evolutionary trends within myxosporean lineages by using 35 new sequences of the LSU rDNA. We show a good agreement between the two rRNA genes and confirm the main phylogenetic split between the freshwater and marine lineages. The informative superiority of the LSU data is shown by an increase of the resolution, nodal supports and tree indexes in the LSU rDNA and combined analyses. We determine the most suitable part of LSU for the myxosporean phylogeny by comparing informative content in various regions of the LSU sequences. Based on this comparison, we propose the D5–3′-end part of the LSU rRNA gene as the most informative region which provides in concatenation with the complete SSU a well resolved and robust tree. To allow for simple amplification of the marker, we design specific primer set for this part of LSU rDNA.     

Morphological and Molecular Identification of the New Species,Trichodina pseudoheterodentata sp. n. (Ciliophora,Mobilida, Trichodinidae) from the Channel Catfish,Ictalurus punctatus,in Chongqing China

It is difficult to differentiate similar trichodinids solely based on morphological examination, thus other identification methods, such as molecular identification, are necessary for identification. One mobilid ciliate named Trichodina pseudoheterodentata sp. n. was isolated from the gills of channel catfish, Ictalurus punctatus, in Chongqing, China. In the present study, its SSU rDNA was sequenced for the first time. Based on the results from both morphological identification and SSU rDNA sequencing, the new species was identified and compared with similar species. The morphological analysis revealed that T. pseudoheterodentata is a large Trichodina species (cell diameter 73.0–82.5 μm) and possesses robust denticles with broad blades and well‐developed blade connections. Characterization of its primary and secondary SSU rDNA structures indicated that T. pseudoheterodentata was distinctly different from congeneric species in H12, H15, E10_1, and V4 regions. Phylogenetic analysis revealed that the genetic distances among the new species and similar species reached interspecific levels, furthermore, the phylogenetic study also validated the identification of T. pseudoheterodentata and its placement in the genus Trichodina.     

Transferring the freshwater dinoflagellate Peridinium wisconsinense (Dinophyceae) to the family Thoracosphaeraceae,with the description of Fusiperidinium gen. nov.

Distinctive spindle‐shaped thecae first described by Samuel Eddy in 1930 and assigned to the genus Peridinium Ehrenberg are commonly reported from freshwater environments in eastern North America. We demonstrate that thecae incubated from cysts of Peridinium wisconsinense Eddy have six cingular plates and a protuberant apical pore complex characteristic of the family Thoracosphaeraceae Schiller 1930 emend. Tangen in Tangen et al . 1982. Small subunit ribosomal DNA (SSU rDNA) and internal transcribed spacer (ITS) sequences confirm the close genetic similarity with Chimonodinium lomnickii (Wo?oszyńska) Craveiro, Calado, Daugbjerg, Gert Hansen & Moestrup and with species recently reassigned to the genus Apocalathium Craveiro, Daugbjerg, Moestrup & Calado that was inferred from previously published LSU rDNA analysis of cysts of P. wisconsinense . Despite sharing identical tabulation with the thoracosphaeracean genera Chimonodinium Craveiro, Calado, Daugbjerg, Gert Hansen & Moestrup and Apocalathium , substantial morphological differences in the morphology of both the thecate and cyst stages of P. wisconsinense led us to reassign this species to the genus Fusiperidinium gen. nov. The phylogenetic position of Fusiperidinium wisconsinense comb. nov., inferred from concatenated data of SSU and LSU sequences, suggests that it evolved from the brackish Scrippsiella lineage, independently of the transition that produced the family Peridiniaceae. Cysts described as Geiselodinium tyonekensis Engelhardt from nonmarine strata from Alaska are apparently identical to the resistant cysts produced by F. wisconsinense . The palynologically‐constrained late Middle Miocene age for the Tyonek Formation provides a minimum age of 11.6 Ma for the evolution of this lineage, coinciding with a rapid glacioeustatic decline in sea level. Our findings also call into question the inclusion of the family Thoracosphaeraceae within the order Peridiniales Haeckel.     

Delimitation of the Thoracosphaeraceae (Dinophyceae), including the calcareous dinoflagellates, based on large amounts of ribosomal RNA sequence data

The phylogenetic relationships of the Dinophyceae (Alveolata) are not sufficiently resolved at present. The Thoracosphaeraceae (Peridiniales) are the only group of the Alveolata that include members with calcareous coccoid stages; this trait is considered apomorphic. Although the coccoid stage apparently is not calcareous, Bysmatrum has been assigned to the Thoracosphaeraceae based on thecal morphology. We tested the monophyly of the Thoracosphaeraceae using large sets of ribosomal RNA sequence data of the Alveolata including the Dinophyceae. Phylogenetic analyses were performed using Maximum Likelihood and Bayesian approaches. The Thoracosphaeraceae were monophyletic, but included also a number of non-calcareous dinophytes (such as Pentapharsodinium and Pfiesteria) and even parasites (such as Duboscquodinium and Tintinnophagus). Bysmatrum had an isolated and uncertain phylogenetic position outside the Thoracosphaeraceae. The phylogenetic relationships among calcareous dinophytes appear complex, and the assumption of the single origin of the potential to produce calcareous structures is challenged. The application of concatenated ribosomal RNA sequence data may prove promising for phylogenetic reconstructions of the Dinophyceae in future.     

A New Heterotrophic Dinoflagellate from the North‐eastern Pacific,Protoperidinium fukuyoi: Cyst–Theca Relationship,Phylogeny, Distribution and Ecology

The cyst–theca relationship of Protoperidinium fukuyoi n. sp. (Dinoflagellata, Protoperidiniaceae) is established by incubating resting cysts from estuarine sediments off southern Vancouver Island, British Columbia, Canada, and San Pedro Harbor, California, USA. The cysts have a brown‐coloured wall, and are characterized by a saphopylic archeopyle comprising three apical plates, the apical pore plate and canal plate; and acuminate processes typically arranged in linear clusters. We elucidate the phylogenetic relationship of P. fukuyoi through large and small subunit (LSU and SSU) rDNA sequences, and also report the SSU of the cyst‐defined species Islandinium minutum (Harland & Reid) Head et al. 2001. Molecular phylogenetic analysis by SSU rDNA shows that both species are closely related to Protoperidinium americanum (Gran & Braarud 1935) Balech 1974. Large subunit rDNA phylogeny also supports a close relationship between P. fukuyoi and P. americanum. Three subgroups in total are further characterized within the Monovela group. The cyst of P. fukuyoi shows a wide geographical range along the coastal tropical to temperate areas of the North‐east Pacific, its distribution reflecting optimal summer sea‐surface temperatures of ~14–18 °C and salinities of 22–34 psu.     

First record of Terpios fugax Duchassaing and Michelotti, 1864 (Demospongiae: Suberitidae) in the Eastern Pacific Ocean

ABSTRACT

The brightly blue shallow water species Terpios fugax Duchassaing and Michelotti, 1864 was originally described from the Caribbean and has been extensively recorded in the Atlantic Ocean, but rarely found in the Indian and Pacific Oceans. In the Pacific Ocean it has been only reported from Sulawesi, Indonesia and from the Caroline and Marshall Islands. Here we report the first record of Terpios in the Eastern Pacific, based on the presence of T. fugax at Caldera, Región de Atacama, northern Chile. Although this species may have been inadvertently introduced to the area by human activity, it should also be considered that the geographically distant populations of this sponge (from the Caribbean to the Eastern Pacific) may represent different species.     

Morphology,morphogenesis, and molecular phylogeny of a novel saline soil ciliate,Heterourosomoida sinica n. sp. (Ciliophora,Hypotrichia)

The living morphology, infraciliature, morphogenesis and phylogenetic position of a new hypotrichous ciliate, Heterourosomoida sinica n. sp., discovered in saline soil in Northwest of China, were investigated. Heterourosomoida sinica n. sp. is characterized as follows: body size about 70–95 × 20–30 μm in vivo, ellipsoid or elongate; cortical granules dark green, 0.5 μm across, arranged around dorsal cilia and in short irregular rows on ventral side; consistently 18 frontoventral-transverse cirri; left and right marginal rows composed of 17–24 and 13–21 cirri, respectively; two macronuclear nodules and one or two micronuclei. The detailed morphogenesis of a species of Heterourosomoida is reported for the first time. The ontogenesis on dorsal side is basically similar to that in Urosomoida-species and the process on ventral side is characterized by: 18 frontoventral-transverse cirri develop from six anlagen with the anlagen V and VI formed in the primary mode. Phylogenetic analyses based on SSU rDNA sequence data reveal that Heterourosomoida sinica n. sp. clusters with Kleinstyla dorsicirrata and forms a clade with the type species H. lanceolata.     

Gambierdiscus (Gonyaulacales,Dinophyceae) diversity in Vietnamese waters with description of G. vietnamensis sp. nov.

Viet Nam has a coastline of 3200 km with thousands of islands providing diverse habitats for benthic harmful algal species including species of Gambierdiscus. Some of these species produce ciguatera toxins, which may accumulate in large carnivore fish potentially posing major threats to public health. This study reports five species of Gambierdiscus from Vietnamese waters, notably G. australes, G. caribaeus, G. carpenteri, G. pacificus, and G. vietnamensis sp. nov. All species are identified morphologically by LM and SEM, and identifications are supported by molecular analyses of nuclear rDNA (D1–D3 and D8–D10 domains of LSU, SSU, and ITS1-5.8S-ITS2 region) based on cultured material collected during 2010–2021. Statistical analyses of morphometric measurements may be used to differentiate some species if a sufficiently large number of cells are examined. Gambierdiscus vietnamensis sp. nov. is morphologically similar to other strongly reticulated species, such as G. belizeanus and possibly G. pacificus; the latter species is morphologically indistinguishable from G. vietnamensis sp. nov., but they are genetically distinct, and molecular analysis is deemed necessary for proper identification of the new species. This study also revealed that strains denoted G. pacificus from Hainan Island (China) should be included in G. vietnamensis sp. nov.     

中国沿海甲藻两个新记录属——艉杆藻属和易碎藻属

艉杆藻属Ensiculifera Balech和易碎藻属Fragilidium Balech的营养细胞和孢囊在中国沿海还未被记录过,作者在中国东海发现了它们的孢囊并通过萌发建立了株系,在光镜和电镜下研究了其细胞形态。一种艉杆藻的孢囊为圆形,直径22μm,双层壁,孢囊体内充满淡绿色的颗粒,有一个鲜艳的红色体,孢囊外壁覆盖着2μm长的有机质短刺;营养细胞上壳圆锥形,下壳圆形,细胞平均长17.7μm,宽12.5μm,甲板方程式为po,x,4′,3a,7″,5c,4s,5′′′,2′′′′。墨西哥易碎藻Fragilidium mexicanum Balech的孢囊为圆形,直径54–60μm,孢囊内充满淡白色的颗粒物以及淡褐色的原生质体,有一个鲜艳的黄色体,萌发孔圆形,偏在孢囊的一侧;营养细胞平均长45.3μm,宽42.8μm,甲板方程式po,5′,7″,10c,7s,7″′,2″″,1P。一种易碎藻的孢囊为圆形,直径45μm,孢囊内充满淡白色的颗粒物以及淡褐色的原生质体,黄色体不明显,细胞壁较厚,2–3μm,无色,萌发孔圆形,偏在孢囊的一侧。细胞平均长41.6μm,宽35.3μm,甲板方程式po,5′,7″,7″′,2″″,1P。对该种艉杆藻的转录间隔区(ITS)、2种易碎藻的小亚基(18S)序列进行了测定并建立了系统发育树,它们的系统发育位置和形态学分类相吻合。     

First record of Asteronema rhodochortonoides (Phaeophyceae) for the Pacific Ocean

Morphological observations of a minute, filamentous, branched brown alga epiphytic on Sargassum thun‐bergii (Mertens ex Roth) Kuntze were made on material collected at Tsuyazaki (33°48′N, 130°27′E), Fukuoka Prefecture, southern Japan. This alga was assignable to Asteronema rhodochortonoides (Børgesen) Möller et Parodi in having stellately arranged chloroplasts with several pyrenoids grouped in the center, predominantly apical growth, narrow filaments, and elliptical or broadly elliptical plurilocular zoidangia that are apically or laterally formed on upright filaments. A comparison of partial nuclear small subunit rDNA sequences between the Japanese material and A. rhodochortonoides from the Canary Islands showed only two or three nucleotide differences. This supports our assignment of the Japanese material to this species as a first report for the Pacific Ocean. In laboratory cultures, zoids released from plurilocular zoidangia developed into plants with morphology similar to the field‐collected plants. This cycle repeated without production of unilocular zoidangia in our cultures.     

中国近海甲藻环沟藻属2个新记录种:纺锤环沟藻和莫氏环沟藻

甲藻环沟藻属于一类无色素体、表面有脊的裸甲藻, 因可捕食一些重要的赤潮生物而在海洋生态系统中扮演着重要的角色。有关中国近海环沟藻属的物种多样性信息非常有限。本文报道了2个新记录种——纺锤环沟藻(Gyrodinium fusiforme)和莫氏环沟藻(G. moestrupii)。纺锤环沟藻细胞呈纺锤形, 长48.0-58.0 μm, 宽18.0-23.0 μm, 长宽比为2.4-3.0, 和模式种相比体型和长宽比都较小。莫氏环沟藻细胞也呈纺锤形, 长约30 μm, 宽约15 μm。我们测定了纺锤环沟藻和莫氏环沟藻大亚基的部分序列, 并根据大亚基序列利用最大似然法和贝叶斯法建立了系统发育树。结果显示环沟藻属是单源的, 纺锤环沟藻和裂缝环沟藻(G. fissum)聚合在一起, 但是与螺旋环沟藻(G. spirale)分离。纺锤环沟藻和莫氏环沟藻分别可以摄食米氏凯伦藻(Karenia mikimotoi)和具齿原甲藻(Prorocentrum dentatum), 前者在米氏凯伦藻赤潮中的大量出现显示它可以促进赤潮的消退。     

Morphological and molecular genetic characterization of Cryptoperidiniopsis brodyi (Dinophyceae) from Australia-wide isolates

Cryptoperidiniopsis brodyi is a common heterotrophic dinoflagellate known to often co-occur with Pfiesteria species in eastern U.S. estuaries. In this study, C. brodyi from Australia and Pfiesteria piscicida from ballast water from Indonesia were characterized by morphological and genetic analyses. Two P. piscicida strains originating from ballast water samples showed little genetic differences compared to P. piscicida from other countries and their morphology was identical. This finding indicates a potential inflow of P. piscicida into Australian estuaries via ballast water. Nine cultures of C. brodyi were established from Tasmania, South Australia and Western Australia. All C. brodyi cultures exhibited identical thecal plate patterns and could not be discriminated from other non-Australian strains. In contrast, two distinct genotypes could be identified by rDNA sequence analyses which were distinct from the U.S. genotype of C. brodyi. A previous survey using PCR-based methods reported a wide distribution of Pfiesteria shumwayae in Australia. However, the present study demonstrated that SSU rDNA-based P. shumwayae-specific primers produce false-positive PCR reactions with Australian C. brodyi. These results suggest that genetic variants of C. brodyi are widely distributed in Australia and Australian genotypes of C. brodyi had previously been misidentified as P. shumwayae. This finding also indicates that previous Australian distribution studies of P. shumwayae using SSU rDNA-based primers are potentially erroneous and need to be revisited.     

Phylogeny of the order Tintinnida (Ciliophora, Spirotrichea) inferred from small- and large-subunit rRNA genes

Concatenated sequences of small- and large-subunit rRNA genes were used to infer the phylogeny of 29 species in six genera of Tintinnida. We confirmed previous results on the positions of major clusters and the grouping of various genera, including Stenosemella, the paraphyletic Tintinnopsis, the newly investigated Helicostomella, and some species of the polyphyletic Favella. Tintinnidium and Eutintinnus were found to be monophyletic. This study contributes to tintinnid phylogenetic reconstruction by increasing both the number of species and the range of genetic markers analyzed.     

Molecular Phylogeny of the Ocelloid-Bearing Dinoflagellates Erythropsidinium and Warnowia (Warnowiaceae, Dinophyceae)

ABSTRACT. Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (= Erythropsis ) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia . Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level.