Systematic revision of the genus Phycodrys (Delesseriaceae,Rhodophyta) from New Zealand,with the descriptions of three new species,P. novae-zelandiae sp. nov., P. franiae sp. nov. and P. adamsiae sp. nov.

Two species of Phycodrys, Phycodrys quercifolia (Bory) Skottsberg and Phycodrys profunda E.Y.Dawson were previously recorded from New Zealand. However, an examination of Phycodrys collections from the New Zealand region showed that all were morphologically different from P. quercifolia (Type locality: the Falkland Islands) and P. profunda (Type locality: CA, USA). RbcL sequence analyses established that the New Zealand Phycodrys species formed a natural assemblage within the genus, consisting of three new species: P. novae-zelandiae sp. nov., P. franiae sp. nov. and P. adamsiae sp. nov. Phycodrys novae-zelandiae is the largest of the three, up to 20 cm in height, with a distinct midrib and multicellular, opposite to subopposite lateral macroscopic veins. It has entirely monostromatic blades except near the midrib and veins, and its procarp contains a three-celled sterile group one (st1) and a one-celled sterile group two (st2). Phycodrys franiae was previously treated as a cryptic species among herbarium collections of P. ‘quercifolia’. It is smaller (4–11 cm high) with weakly developed midribs and veins, the blade is tristromatic throughout, except at the growing margins, and the procarp consists of a four-celled st1 and a two–three-celled st2. Phycodrys adamsiae, previously reported as P. profunda, is a small decumbent or prostrate plant, 1–8 cm long, with a midrib and inconspicuous lateral veins. The blades are tristromatic with serrated margins, two–four-celled surface spines and multicellular marginal holdfasts that differ from those of Californian specimens. The tetrasporangia are borne on marginal bladelets. Phylogenetic analyses place the New Zealand species in a separate group that is distantly removed from most other Phycodrys species.     

Polysiphonia freshwateri sp. nov. and Polysiphonia koreana sp. nov.: two new species of Polysiphonia (Rhodomelaceae,Rhodophyta) from Korea

Polysiphonia sensu lato comprises approximately 200 species, which are currently assigned to several different genera. To date, one of these genera, namely, Polysiphonia, has been reported to have 17 species. Here, we describe for the first time P. freshwateri sp. nov. and P. koreana sp. nov. from Uljin and Ulleung Island, Korea, based on morphological and molecular evidence. Polysiphonia freshwateri sp. nov. and P. koreana sp. nov. are characterized by having the typical Polysiphonia features. Polysiphonia freshwateri sp. nov. is further characterized by having abundant trichoblasts, conspicuous scar cells, and tetrasporangia arranged in spiral series. Polysiphonia koreana sp. nov. is further characterized by having very scarce scar cells placed between two pericentral cells, from which cicatrigenous branches arise. The results of our rbcL sequence analyses support the taxonomic placement of P. freshwateri sp. nov. and P. koreana sp. nov. within Polysiphonia.     

Xenococconeis opunohusiensis gen. et sp. nov. and Xenococconeis neocaledonica comb. nov. (Bacillariophyta) from the tropical South Pacific

During a survey of the coral reef diatoms of Moorea Island (Society Archipelago, South Pacific) a small‐sized member of the order Achnanthales was studied using a light microscope (LM) and a scanning electron microscope (SEM). This marine taxon has: a raphe valve (RV) with a non‐crenulate edge; a high cingulum; a sternum valve (SV) often irregularly striated and areolae with concave hymenate pore occlusion; a thick and plain SV valvocopula (SVVC), ring‐shaped, composed of large fused fimbriae, with a central elliptic foramen bordered by the peg‐like edge of the fimbriae. On abvalvar side, the SVVC bears radiate concave and robust transapical ribs, interlinking with short elevated transverse ribs of the RV valvocopula (RVVC). Large marginal fenestrae of the RVVC give access to pseudoloculi. One oblong, unique and striated papilla is located on each RVVC rib. Given this unique set of features, we describe Xenococconeis opunohusiensis gen. et sp. nov. as a new taxon belonging to the Achnanthales. The characteristics of the new taxon are compared with Campyloneis Grunow and Cocconeis Ehrenberg. From New Caledonia, Cocconeis neocaledonica Maillard ex Lange‐Bertalot et Steindorf, a freshwater diatom, was described with two internal septa with marginal pseudoloculi. Based on subsequent SEM illustrations and remarks, we propose the transfer of C. neocaledonica to the new genus, and compare it to the type species, Xenococconeis opunohusiensis.     

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.     

Classification of novel soil streptomycetes as Streptomyces aureus sp. nov., Streptomyces laceyi sp. nov. and Streptomyces sanglieri sp. nov

The taxonomic positions of soil isolates known as Streptomyces groups A, B and C were clarified. Comparative 16S rDNA sequence studies indicated that representatives of all three taxa formed distinct phyletic lines within the Streptomyces tree though the group A strains were shown to be related to Streptomyces griseus and associated validly described species. The taxonomic integrity of all three groups was highlighted by DNA:DNA relatedness and ribotype data though the group A strains encompassed a higher degree of genetic variation than the group B and C strains. In light of these and earlier phenotypic data it is proposed that Streptomyces groups A, B and C be given species status as Streptomyces sanglieri sp. nov., Streptomyces aureus sp. nov. and Streptomyces laceyi sp. nov., respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Zygotorulaspora cornina sp. nov. and Zygotorulaspora smilacis sp. nov., Two Novel Ascomycetous Yeast Species Isolated from Plant Flowers and Fruits

Three isolates belonging to the ascomycetous genus Zygotorulaspora were obtained from the fruits of Cornus officinalis and Smilax china, and flowers of Dendranthema zawadskii var. latilobum in Gongju-si, Korea. Phylogenetic Analyses of the LSU D1/D2 domain and ITS region sequences supported the recognition of two new species: Zygotorulaspora cornina sp. nov. (type strain NIBRFGC000500475 = KACC93346P^PP) and Zygotorulaspora smilacis sp. nov. (type strain NIBRFGC000500476 = KACC93347P^PP). The two novel species revealed no growth on D-Galactose, unlike the other six species in the genus Zygotorulaspora. They are distinguished from each other by their phylogenetic differences and phenotypic characteristics such as assimilation of xylitol, 5-keto-D-gluconate, and ethanol. All species in the genus Zygotorulaspora including the two novel species have phenotypic traits of genus Zygotorulaspora: asci are persistent, sucrose and raffinose are assimilated, and m-inositol is not required for growth, and they are mainly associated with plants.     

Etheliaceae fam. nov. (Gigartinales,Rhodophyta), with a clarification of the generitype of Ethelia and the addition of six novel species from warm waters

Based upon COI‐5P, LSU rDNA, and rbcL sequence data and morphological characteristics, six new members of the noncalcified crustose genus of red algae Ethelia are described in a new family, Etheliaceae (Gigartinales), sister to the recently described Ptilocladiopsidaceae. The novel species are described from subtropical to tropical Atlantic and Indo‐Pacific Ocean basins; E. mucronata sp. nov. and E. denizotii sp. nov. from southern and northern Western Australia respectively, E. wilcei sp. nov. from the Cocos (Keeling) Islands of Australia, E. suluensis sp. nov. from the Philippines, E. umbricola sp. nov. from Bermuda and E. kraftii sp. nov. from Lord Howe Island, Australia. The generitype, Ethelia biradiata, originally reported from the Seychelles, Indian Ocean, is added to the Western Australian flora.     

Morphology and taxonomy of five marine sand-dwelling Thecadinium species (Dinophyceae) from Japan, including four new species: Thecadinium arenarium sp. nov., Thecadinium ovatum sp. nov., Thecadinium striatum sp. nov. and Thecadinium yashimaense sp. nov.

Thecadinium inclinatum Balech and four new marine sand‐dwelling species of the dinoflagellate genus Thecadinium are described from the sandy beaches along the coast of Shikoku, Japan. Thecadinium inclinatum is thecate, bilaterally flattened, elliptical in shape, non‐photosynthetic, and measures 55–75 μ in length and 43–59 μ in depth. The epi‐ and hypotheca theca are semielliptical and the thecal surface is smooth with small pores. The plate formula is Po (pore plate), 3′, 7″,?c,?s, 5″′1″′.Thecadinium ovatum sp. nov. is thecate, non‐photosynthetic, bilaterally flattened and almost oval in lateral view. The cell measures 40–50 μm in length and 33–40 μm in depth. The hypotheca has two or three strong antapical spines. The plate formula is 3′, 6″,6c, 5s?, 5″′, 1″′. Thecadinium striatum sp. nov. is thecate, non‐photosynthetic, bilaterally flattened and somewhat elliptical in lateral view. The cell is 33–41 μm long and 23–30 μm deep. Several striae are present on the hypotheca. The plate formula is 3′, 6″, 6c, 5s?, 5″′, 1″″. Thecadinium yashimaense sp. nov. is bilaterally flattened, photosynthetic and elliptical in ventral view. The cell is 44–65 μm long and 23–36 μm wide. The thecal surface is smooth with small pores. he cingulum forms a steep left–handed spiral. The plate formula is Po, 3′, la, 6″, 5c, 4s, 5″′, 1″′. Thecadinium arenarium sp. nov. is somewhat wedge‐shaped in ventral view, photosynthetic with brownish chloroplasts and almost rounded in cross section. The cingulum forms a steep left‐handed spiral. The cell measures 35–41 μm in length and 25–30 μm in width. The thecal surface is weakly reticulated with small pores. The hypotheca is conical. The plate formula is Po, 3′, la, 6″, 5c, 4s, 5″′, 1″″.     

Life cycle,morphology of developmental stages of Metorchis ussuriensis sp. nov. (Trematoda: Opisthorchiidae), and phylogenetic relationships with other opisthorchiids

The complete life cycle and developmental stages of the fluke, Metorchis ussuriensis sp. nov. (Trematoda, Platyhelminthes), are herein described. The results of the present experiments showed that, for flukes from the Primorsky Region in the Russian southern Far East, the first intermediate hosts are the snails Parafossarulus spiridonovi and Boreoelona ussuriensis, and the second intermediate hosts are freshwater fish, tadpoles, and snails. The definitive host in this experiment was Anas platyrhynchos dom. Morphometric parameters of M. ussuriensis sp. nov. demonstrate similarities with Metorchis taiwanensis, but the two species differ in the sizes of their bodies, sizes of suckers of adult worms, and sizes of cercariae, as well as respective positions of the finfold in cercariae. Phylogenetic reconstructions and genetic distances using the cox1 gene sequences support the conclusion that M. ussuriensis sp. nov. is well distinguished from all other species of the genus Metorchis, while sequences of internal transcribed spacers (ITS1 and ITS2) failed to separate M. ussuriensis sp. nov., Metorchis bilis, and Metorchis xanthosomus. In addition, we sequenced 1,402 bp of the 28SrRNA gene of M. ussuriensis sp. nov. being the first 28S sequences in the genus Metorchis. Comparison to other trematodes suggests that 28SrRNA could proof suitable for the differentiation of trematode species.     

Heliobacterium sulfidophilum sp. nov. andHeliobacterium undosum sp. nov.: Sulfideoxidizing heliobacteria from thermal sulfidic springs

Two new species of heliobacteria isolated from cyanobacterial mats of two alkaline sulfidic hot springs are formally described. Strains BR4 and BG29 are assigned to anoxygenic phototrophic bacteria of the familyHeliobacteriaceae, since they possess the unique properties of this taxon: strict anaerobiosis, formation of bacteriochlorophyllg, the lack of extensive intracytoplasmic membranes and chlorosomes, an unusual cell wall structure, and phylogenetic relatedness to the low G+C gram-positive eubacteria. Based on the 16S rDNA sequence similarity, strains BR4 and BG29 are assigned to the genusHeliobacterium and described as two new species of this genus:Heliobacterium sulfidophilum sp. nov. andHeliobacterium undosum sp. nov. The G+C content of the DNA is 51.3 mol % inHbt. sulfidophilum and 57.2-57.7 mol % inHbt. undosum. The cells ofHbt. sulfidophilum are rods, and the cells ofHbt. undosum are slightly twisted spirilla or short rods. Both new bacteria are motile by peritrichous flagella.Hbt. sulfidophilum produces endospores. The new bacteria are strict anaerobes growing photoheterotrophically on a limited range of organic compounds. In the dark, they can switch from photosynthesis to the slow fermentation of pyruvate. Biotin is required as a growth factor. Both species are highly tolerant to sulfide (up to 2 mM at pH 7.5) and oxidize it photoheterotrophically to elemental sulfur; photoautotrophic growth was not observed. The temperature optimal for growth ofHbt. sulfidophilum andHbt undosum is 30–35‡C, and the optimal pH is 7–8.     

Bullera begoniae sp. nov. and Bullera setariae sp. nov., two new species of ballistoconidium-forming yeasts in the Bullera variabilis (Bulleribasidium) cluster isolated from plants in Taiwan

Two strains of xylose-containing and Q-10-having ballistoconidiogenous yeasts isolated from plant leaves collected in Taiwan were found to represent two new species of the genus Bullera. In the phylogenetic trees based on the sequence analysis of 18S rDNA and D1/D2 domain of 26S rDNA, these species are located in the Bullera variabilis (Bulleribasidum) cluster in Hymenomycetes. They are described as Bullera begoniae sp. nov. and Bullera setariae sp. nov., respectively.     

Morphology and molecular phylogeny of three new oligotrich ciliates (Protozoa,Ciliophora) from the South China Sea

The present paper documents the morphology and systematic positions of three new oligotrich ciliates, P arallelostrombidium obesum sp. nov. , P arallelostrombidium ellipticum sp. nov. , and S trombidium tropicum sp. nov. , which were sampled from habitats with different salinities in southern China. P arallelostrombidium obesum sp. nov. is characterized by a fat body and the posterior portions of the girdle and ventral kineties extending transversely on the dorsal side. P arallelostrombidium ellipticum sp. nov. is recognizable by the anterior ends of the girdle and ventral kineties being close to each other and the posterior ends of the girdle and ventral kineties intersecting on the dorsal side. S trombidium tropicum sp. nov. is distinguished by a ventrally opened girdle kinety that is slightly spiralled with the right end shifted posteriad. Small subunit rRNA gene trees show that P . obesum sp. nov. and P . ellipticum sp. nov. fall into a mixed group composed of Parallelostrombidium and some Novistrombidium species, and that S . tropicum sp. nov. branches at the base of the clade containing non‐Strombidium species. The relationships of Parallelostrombidium species and that of Strombidium species are both not resolved considering their low support values in our phylogenetic analysis. © 2015 The Linnean Society of London     

Microcostatus schoemanii sp. nov., M. cholnokyi sp. nov. and M. angloensis sp. nov. three new terrestrial diatoms (Bacillariophyceae) from South Africa

The terrestrial diatom Microcostatus schoemanii sp. nov. is described from dry soils of the Faan Meintjies Nature Reserve (North‐West Province, South Africa). Microcostatus cholnokyi sp. nov. and Microcostatus angloensis sp. nov. are described from sandy soils at a colliery near the town of Kriel (Mpumalanga Province, South Africa). The morphology of these taxa is examined using both light and scanning electron microscopy and new taxa are compared with similar species. In M. schoemanii the density of the striae combined with the valve outline and the distance between the central raphe endings are the main distinguishing morphological features. M. cholnokyi is differentiated by the presence of a conopeum and the distinct structure of the microcostae. M. angloensis is similar to M. schoemanii but differentiated by the shape of the cell and the apices, the angle of striation and the distance in between the proximal raphe endings.     

NEW MARINE MEMBERS OF THE GENUS HEMISELMIS (CRYPTOMONADALES,CRYPTOPHYCEAE)1

Cryptomonads are a ubiquitous and diverse assemblage of aquatic flagellates. The relatively obscure genus Hemiselmis includes some of the smallest of these cells. This genus contained only two species until 1967, when Butcher described seven new marine species mainly on the basis of observations with the light microscope. However, from these seven taxa, only H. amylifera and H. oculata were validly published. Additionally, the features Butcher used to distinguish species have since been questioned, and the taxonomy within Hemiselmis has remained clouded due to the difficulty in unambiguously applying his classification and validating many of his species. As a result, marine strains are often placed into one of three species—H. rufescens Parke, H. virescens Droop, or the invalid H. brunnescens Butcher—based on cell color alone. Here we applied microscopic and molecular tools to 13 publicly available Hemiselmis strains in an effort to clarify species boundaries. SEM failed to provide sufficient morphological variation to distinguish species of Hemiselmis, and results from LM did not correlate with clades found using both molecular phylogenetic and nucleomorph genome karyotype analysis, indicating a high degree of morphological plasticity within species. On the basis of molecular characters and collection geography we recognize four new marine species of Hemiselmis—H. cryptochromatica sp. nov., H. andersenii sp. nov., H. pacifica sp. nov., and H. tepida sp. nov.—from the waters around North America.     

Rhodeus pseudosericeus sp. nov., a new bitterling from South Korea (Cyprinidae, Acheilognathinae)

A new bitterling, Rhodeus pseudosericeus sp. nov., is described on the basis of 31 specimens from five localities included in the Namhan River system, South Korea. The new species is distinguished from other Rhodeus species by the following combination of characters: branched dorsal fin rays 9–10 (mode 9); branched anal fin rays 9–11 (mode 10); longest simple ray of dorsal fin strong and stiff, distally segmented; pelvic fin rays i, 6–7; iris of males blackish; dorsal and anal fins of males grayish in breeding season; karyotype with 2n = 48 (8m + 20sm + 20st). Rhodeus pseudosericeus sp. nov. is similar to Rhodeus sericeus sericeus in the number of pelvic fin and branched dorsal fin rays and the melanophores present on the dorsal fin membrane, but differs from the latter in having a greater body depth, more branched anal fin rays, fewer vertebrae, a lower number of scales in the lateral series, and differing male nuptial coloration. Received: June 30, 2000 / Revised: February 21, 2001 / Accepted: March 6, 2001     

Candida alocasiicola sp. nov., Candida hainanensis sp. nov., Candida heveicola sp. nov. and Candida musiphila sp. nov., novel anamorphic, ascomycetous yeast species isolated from plants

In a taxonomic study on the ascomycetous yeasts isolated from plant materials collected in tropical forests in Yunnan and Hainan Provinces, southern China, four strains isolated from tree sap (YJ2E(T)) and flowers (YF9E(T), YWZH3C(T) and YYF2A(T)) were revealed to represent four undescribed yeast species. Molecular phylogenetic analysis based on the large subunit (26S) rRNA gene D1/D2 domain sequences showed that strain YJ2E(T) was located in a clade together with Candida haemulonii and C. pseudohaemulonii. Strain YF9E(T) was most closely related to C. azyma and strain YWZH3C(T) to C. sorbophila and C. spandovensis. Strain YYF2A(T) was clustered in a clade containing small-spored Metschnikowia species and related anamorphic Candida species. The new strains differed from their closely related described species by more than 10% mismatches in the D1/D2 domain. No sexual states were observed for the four strains on various sporulation media. The new species are therefore assigned to the genus Candida and described as Candida alocasiicola sp. nov. (type strain, YF9E(T) = AS 2.3484(T) = CBS 10702(T)), Candida hainanensis sp. nov. (type strain, YYF2A(T) = AS 2.3478(T) = CBS 10696(T)), Candida heveicola sp. nov. (type strain, YJ2E(T) = AS 2.3483(T) = CBS 10701(T)) and Candida musiphila sp. nov. (type strain, YWZH3C(T) = AS 2.3479(T) = CBS 10697(T)).     

Studies of the Liagoraceae (rhodophyta) of Western Australia: Gloiotrichus fractalis gen. et sp. nov. and Ganonema helminthaxis sp. nov.

Two new taxa of Liagoraceae (Nemaliales) are described from Western Australia. Gloiotrichus fractalis gen. et sp. nov. has been collected from 3–20 m depths at the Houtman Abrolhos, Western Australia. Plants are calcified, extremely lubricous, and grow to 17 cm in length. Carpogonial branches are straight, 6 or 7 cells in length, arise from the basal or lower cells of cortical fascicles, and are occasionally compound. Branched sterile filaments of narrow elongate cells arise on the lower cells of the carpogonial branch prior to gonimoblast initiation, at first on the basal cells, then on progressively more distal cells. Following presumed fertilisation the carpogonium divides transversely, with both cells giving rise to gonimoblast filaments. The distal cells of the carpogonial branch then begin to fuse, with fusion progressing proximally until most of the cells of the carpogonial branch are included. As fusion extends, the filaments on the carpogonial branch are reduced to the basal 2 or 3 cells. The gonimoblast is compact and bears terminal carposporangia. Spermatangial clusters arise on subterminal cells of the cortex, eventually displacing the terminal cells. The sequence of pre- and post-fertilisation events occurring in the new genus separates it from all others included in the Liagoraceae, although it appears to have close affinities with the uncalcified genus Nemalion. Ganonema helminthaxis sp. nov. was collected from 12 m depths at Rottnest Island, Western Australia. Plants are uncalcified and mucilaginous, the axes consisting of a few (< 10) primary medullary filaments, each cell of which gives rise to a cortical fascicle at alternate forks of the pseudodichotomies borne on successive medullary cells. Subsidiary (adventitious) filaments and rhizoids comprise the bulk of the thallus. Carpogonial branches are straight, (3-)4(-6) cells in length, arise on the basal 1–4 cells of the cortical fascicles, and are frequently compound. Carposporophytes develop from the upper of two daughter cells formed by a transverse division of the fertilised carpogonium. Ascending and descending sterile filaments girdle the carpogonial branch cells and arise mostly on the supporting cell prior to fertilisation. Ganonema helminthaxis is the first completely non-calcified member of the genus, and its reproductive and vegetative morphology supports the recognition of Ganonema as a genus independent from Liagora. Liagora codii Womersley is a southern Australian species displaying features of Ganonema, to which it is transferred.     

The genus Phyllomyza Fallén (Diptera: Milichiidae) from Japan, with descriptions of four new species

The Japanese species of the genus Phyllomyza Fallén are revised. Four new species, Phyllomyza kanmiyai sp. nov., P. amamiensis sp. nov., P. proceripalpis sp. nov. and P. japonica sp. nov., are described and illustrated. P. securicornis Fallén is recorded from Japan for the first time. A key to the Japanese species of Phyllomyza is presented.     

Morphology and Phylogeny of Prorocentrum texanum sp. nov. (Dinophyceae): A New Toxic Dinoflagellate from the Gulf of Mexico Coastal Waters Exhibiting Two Distinct Morphologies

A new planktonic species of Prorocentrum is described from the Gulf of Mexico. First observed with the Imaging FlowCytobot, Prorocentrum texanum sp. nov. was characterized using LM, SEM, and TEM along with sequencing of the SSU, LSU, and ITS ribosomal regions and the mitochondrial cob and cox1 regions. P. texanum sp. nov. is a round to oval bivalvate dinoflagellate, with a prominent anterior, serrated solid flange on periflagellar a platelet and an opposing short, flat flange on the h platelet. The periflagellar area consists of 10 platelets. Both left and right valves have shallow round depressions and two‐sized valve pores. The anterior ejectosome pore pattern differs between the left and right valve in relation to the periflagellar area and margins. Ten to eleven rows of tangential ejectosome pores are present on each valve. P. texanum sp. nov. has two varieties which exhibit distinct morphotypes, one round to oval (var. texanum) and the other pointed (var. cuspidatum). P. texanum var. cuspidatum is morphologically similar to P. micans in surface markings, but is smaller, and has a serrated periflagellar flange, and is genetically distinct from P. micans. Cytologically, P. texanum has two parietal chlo‐roplasts, each with a compound, interlamellar pyrenoid, trichocysts, fibrous vesicles that resemble mucocysts, pusules, V‐ to U‐shaped posterior nucleus, golgi, and tubular mitochondria. No genetic difference was found between the two varieties in the five genes examined. Phylogenetic analysis of the SSU, LSU, and ITS ribosomal regions place P. texanum sp. nov. as a sister group to P. micans. One isolate of P. texanum var. texanum produces okadaic acid.