DOI: 10.3897/phytokeys.269.179128

Authors: Evgeniy S. Gusev, Tatiana V. Safronova, Yulia А. Podunay, Hoan Tran, Alma B. Mohagan, Nikita A. Martynenko

Abstract: This research is devoted to the study of Mallomonas species from the section Multisetigerae in a tropical region (Vietnam and the Philippines) using electron microscopy and molecular studies. For the first time, molecular data and phylogenetic relationships for species within this section are presented. Analysis of six algal cultures, based on a combined dataset of SSU rDNA and rbcL genes, as well as the ITS1–5.8S–ITS2 rDNA region, revealed three distinct clades. Notably, these clades did not form a monophyletic grouping. Two of the studied cultures were identified as Mallomonas multisetigera, and another two as M. neoampla. For the remaining clade, we describe a new species, Mallomonas rutabuliformis sp. nov., which combines morphological features of fossil and modern taxa. The study also synthesizes original and literature data on the distribution of the Mallomonas multisetigera morphotype.

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DOI: 10.3897/phytokeys.269.179287

Authors: Evgeniy S. Gusev, Nikita A. Martynenko, Irina N. Sterlyagova, Raisa M. Khatsaeva, Hoan Tran, Boris D. Efeykin, Marina E. Ignatenko

Abstract: This study investigates the Mallomonas adamas species complex in a tropical region using electron microscopy and molecular phylogeny. Analysis of four algal cultures from Vietnam, supplemented by data from two cultures from Europe and one from Australia, all belonging to the M. adamas morphotype, revealed two distinct clades in phylogenetic trees based on SSU rDNA + rbcL cpDNA and ITS1–5.8S–ITS2 rDNA sequences. Based on these results, a new species, Mallomonas imperatoria sp. nov., is described. Mallomonas imperatoria was found in 22 localities across nine provinces in Vietnam and is also known from Malaysia. This species generally prefers acidic water bodies, including those that are humic-stained, with low mineralization. Thus, findings of this taxon are not very frequent, but it cannot be classified as rare in the tropical region.

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DOI: 10.3897/phytokeys.268.178310

Authors: Evgeniy S. Gusev, Marina E. Ignatenko, Nikita A. Martynenko, Hoan Tran, Chris Rey Lituanas, Yulia A. Podunay

Abstract: Mallomonas guttata species complex was investigated in a tropical region using electron microscopy and molecular phylogeny. A study of six algal cultures belonging to the M. guttata morphotype revealed two main clades based on two datasets (SSU rDNA+rbcL cpDNA, and ITS rDNA). This work establishes the phylogenetic position of M. guttata for the first time. We propose the new species, M. monilifera sp. nov., for organisms from the second clade, which were distinguished by the presence of a rim around the pits located on the shield on their scales and showed considerable genetic distances from the M. guttata clade. Within this new species, the strains formed two subclades, for which we propose two subspecies. Scales of the new species were also found in several water bodies on Mindanao Island (Philippines).

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DOI: 10.3897/phytokeys.268.176758

Authors: Evgeniy S. Gusev, Marina E. Ignatenko, Chris Rey Lituanas, Kyla Rose Gumapac, Nikita A. Martynenko, Boris D. Efeykin

Abstract: This study presents the first comprehensive investigation of chrysophytes from the Philippines. The flora of silica-scaled chrysophytes from freshwaters of Mindanao Island has been studied by means of scanning and transmission electron microscopy. A total of thirty-six taxa were recorded, including three belonging to Paraphysomonas, two to Spiniferomonas, one to Lepidochromonas, twenty-nine to Mallomonas and one to Synura. A new species, Mallomonas pseudopustula sp. nov., was discovered and described. Several unidentified Mallomonas taxa were also recorded. The flora of silica-scaled chrysophytes of the Mindanao Island is similar to the flora of neighbouring countries — Vietnam, Indonesia and Malaysia.

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DOI: 10.3897/phytokeys.260.154552

Authors: Jun-Xue Hao, Ya-Lu An, Fang-Ru Nan, Jun-Ping Lv, Qi Liu, Xu-Dong Liu, Shu-Lian Xie, Jia Feng

Abstract: The genus Epipyxis, belonging to the family Dinobryaceae, has been documented to have only sporadic occurrences in freshwater habitats. However, the species diversity of this genus remains largely unexplored due to the scarcity of available molecular sequences. This limitation has significantly hindered a comprehensive understanding of both the species diversity and evolutionary relationships of the genus Epipyxis. In this study, a new species Epipyxis fenheensis sp. nov. was described from Shanxi Province, China, based on detailed morphological observations and phylogenetic analyses. This species was characterized by a tube-like lorica, a spindle protoplast, two heterokont flagella, and oval or elliptic scales. In addition, phylogenetic analysis based on multi-genes (SSU, LSU, and rbcL) indicated that strain SX231009 was closely related to E. pulchra. Given its distinct morphological characteristics and independent phylogenetic position, we propose the designation of this strain as a new species, E. fenheensis sp. nov. The results of this study significantly expand the known diversity of the genus Epipyxis and provide valuable insights into the regional biodiversity and evolutionary history of freshwater chrysophytes.

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