Chodatodesmus intermedia I.N. Egorova, N.V. Kulakova & Ye.D. Bedoshvili, 2025

Egorova, Irina Nikolayevna, Kulakova, Nina Viktorovna & Bedoshvili, Yekaterina Dzhambulatovna, 2025, Diversity of the scenedesmacean genus Chodatodesmus (Chlorophyta) and new cryptic species in the algae flora of Lake Baikal revealed by an integrative approach, Organisms Diversity & Evolution 25 (2), pp. 249-267 : 260-261

Chodatodesmus intermedia I.N. Egorova, N.V. Kulakova & Ye.D. Bedoshvili , sp. nov.

Description: Vegetative cells are solitary, globose, subglobose, elliptical, rarely lemon-shaped, 3.0–12(13.9) × 3–12 μm in size. The cell wall is colorless, smooth, sometimes with visible polar thickening in LM. In SEM, it has a wrinkled cell wall with one or more ribs. The chloroplast is parietal, at times lobed, with a pyrenoid surrounded by continuous or several (2–3 or more) starch grains. Individual cells contain 2–3 pyrenoids. The cells are uninucleate. Several large or small vacuoles and/or oil droplets can be found in the cellular space. Old cells are mostly spherical and subspherical. Their cell wall is smooth. One to three thickenings can be noticeable in LM. Individual aging cells are 16 μm in diameter. The contents of aging cells become homogeneous, orange. Occasionally, one or more pyrenoids are noticeable in it. Vacuoles can be present in the cytoplasm of some old cells. Cultures at 2–6 months of age or more are red, orange, or red-brown. Asexual reproduction occurs via 2–16 autospores. Autosporangia are 8–16 × 7–15 μm in size, sometimes up to 20(30) μm in diameter. The liberation of autospores is by rupturing the mother cell wall. Autospores are globose, ellipsoidal, tetrahedral, and lemon-shaped, often with polar thickenings. The remnants of mature call walls present in culture.

Diagnosis: Differs from other species of the genus Chodatodesmus by ITS, rbc L and tuf A sequences. From C. australis , strain Gondwana, it differs by 5, 26, 15, and 4 nucleotide bases in the 18S rRNA gene, ITS, rbc L, and tuf A, respectively.

Holotype (designated here): a drop of unfixed cells of the strain IRK-A 449 was placed on a membrane filter, dried and preserved in a metabolically inactive stage at Herbarium of Siberian Institute of Plant Physiology and Biochemistry of SB RAS ( IRK), Irkutsk, Russia, under number 003117.

Isotype (designated here): dried specimens deposited into Herbarium ( IRK) of SIPPB SB RAS under accession numbers 003117–1 , 003117–2 , 003117–3 , and 003117–4 , and in the Algological Herbarium of Komarov Botanical Institute RAS ( LE), Saint-Petersburg, Russia, numbers LE A0006730 , LE A0006731 , and LE A0006732 . Additionally, the formaldehyde–fixed strain, IRK-A 449, is stored in SIPPB SB RAS .

Type locality and habitat: Russian Federation, Irkutsk region, Slyudyansky district, the surroundings of the Murino village, Lake Baikal , coastal ice, 51° 29ʹ N, 104° 24ʹ E.

Etymology: the epithet “intermedia ” refers to the English word “intermediate.” It indicates the phylogenetic position of the new species between two known species of the genus.

Comment: The ITS1-ITS2 sequences from soil metagenomes deposited in GBIF under number SH1016914.09FU belong to Chodatodesmus intermedia .