identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03CA8782DF43C20FFF17F8D8FAF0FDFA.text	03CA8782DF43C20FFF17F8D8FAF0FDFA.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus Genkal, Kulikovskiy, Glushchenko & Tseplik 2025	<div><p>Stephanoarcus Genkal, Kulikovskiy, Glushchenko &amp; Tseplik gen. nov.</p><p>Type species (here designated): Stephanoarcus triporus (Genkal &amp; Kuzmin) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov.</p><p>Description</p><p>Cells low cylindrical to disc-shaped. The valves are circular, flat, convex or concave. Valve structure consisting of radial ribs or hyaline interfascicles and fascicles of areolae between them that consist of single areolae near the center, and 2–4 areolae per fascicle towards the edge of the valve. Fascicles continue onto valve mantle without significant change in structure of areolae. In the center of the valve there is one or several areolae located randomly; rarely the center is hyaline. Areolae are locular, with a foramen on the external surface of the valve, and a domed velum on the inside. Interfascicles usually end in spines or spinules at the junction between valve face and mantle, less often the spines are absent. Valves with a single valve face fultoportula with 2–4 satellite pores. Marginal fultoportulae have 3 satellite pores on the inside of the valve and open on the outside at the edge of the valve with an arch-like structure. A single rimoportula is located in the ring of spines, externally forming a tube and opening as a labiate slit internally.</p><p>Etymology: The genus name reflects the presence of arch-like structures at the valve edge as one of the defining features and the similarity between the new genus and Stephanodiscus . This genus name is treated as masculine.</p></div>	https://treatment.plazi.org/id/03CA8782DF43C20FFF17F8D8FAF0FDFA	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
03CA8782DF40C20FFF17FD68FE9BFAE6.text	03CA8782DF40C20FFF17FD68FE9BFAE6.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus triporus (Genkal, Kulikovskiy, Glushchenko & Tseplik 1310) Genkal, Kulikovskiy, Glushchenko & Tseplik 2025	<div><p>Stephanoarcus triporus (Genkal &amp; Kuzmin) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov. (Figs 1–6)</p><p>Basionym: Stephanodiscus triporus Genkal &amp; Kuzmin 1978 . Botanicheskii Zhurnal 63(9): 1310, pl. 2: figs 1–8.</p><p>Synonyms: Stephanodiscus triporus var. volgensis Genkal in Genkal &amp; Korneva 1990; Praestephanos triporus (Genkal &amp; Kuzmin) Tuji &amp; J.-S. Ki in Tuji et al. 2014.</p><p>Description. Cells single, low cylindrical. Valves flat or with a slightly convex or concave center, 3.7–14.5 µm in diameter, 10–30 striae, 23–61 areolae in 10 µm (n = 52). Fascicles consist of 1 areola at the center and 2–3 areolae towards the valve edge. In the center of the valve areolae are located irregularly, often there is one larger areola and 1, rarely 2 valve face fultoportulae with 2–4 satellite pores. Spines are small and pointed, located on each costa at the junction of valve face and mantle, sometimes absent; density 18–23 in 10 μm. Marginal fultoportulae with 3 satellite pores on the inside of the valve, on the outside opening into an arch-like structure at the edge of the valve, its opening varied from narrow to wide, sometimes with sector-shaped flaps, located under each 2–5 spines; density about 4.2–4.8 in 10 μm. A single sessile rimoportula with a long conical tube on the outside of the valve, located in the ring of spinules, and a labiate slit on the inside, oriented tangential to radial.</p><p>Ecology: Freshwater and brackish water plankton species.</p><p>Found in: Volga Reservoirs, Tsimlyanskoye and Revdinskoye Reservoirs (Middle Ural), Sestroretsky spill, Lake Verhnee Latvo (Karelia), Lake Ladoga, Lake Baikal, rivers Nyukhcha and Shigerendzha (Karelia), Oka, Izhora, Ob, Klyazma, Selenga, the Purparod Channel (Gydan Peninsula, Messoyakha river basin), Curonian Lagoon, Baltic Sea, Caspian Sea.</p></div>	https://treatment.plazi.org/id/03CA8782DF40C20FFF17FD68FE9BFAE6	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
03CA8782DF40C20EFF17FA54FED6FF50.text	03CA8782DF40C20EFF17FA54FED6FF50.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus vestibulis (Genkal, Kulikovskiy, Glushchenko & Tseplik 2025) Genkal, Kulikovskiy, Glushchenko & Tseplik 2025	<div><p>Stephanoarcus vestibulis (Håkansson, Theriot &amp; Stoermer) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov. (Figs 7–30)</p><p>Basionym: Stephanodiscus vestibulis Håkansson, Theriot &amp; Stoermer 1986 . Nordic Journal of Botany 6(4): 504, figs 1–10.</p><p>Synonyms: S. triporus sensu Genkal &amp; Trifonova, 2006, Table IV, 9; S. triporus sensu Genkal &amp; Trifonova, 2009, Table VIII, 3; S. triporus sensu Genkal &amp; Kuzmin in Genkal 2013, Tab. IV, 1, 3; S. triporus sensu Genkal et al., 2011, Table IV, 5, 6; S. triporus sensu Genkal &amp; Belyaeva, 2011, Tab. IV, 1–3.</p><p>Description. Cells single, low cylindrical. Valves circular, with a strongly convex or concave center, 4–13 µm in diameter, 11–16 striae in 10 µm, 33–37 areolae in 10 μm (n = 34). Interfascicles strongly raised on the outside, in highly silicified valves connected with crossbars. Fascicles consist of 1 areola at the center and 2–4 areolae towards the valve edge, areolae round to elliptic. In the center of the valve the areolae are arranged irregularly, often there is one larger areola and a single valve face fultoportula with 2–4 satellite pores. The spines are large and pointed, located on costae at the junction of valve face and mantle; density 14–18 in 10 μm. Marginal fultoportulae with 3 satellite pores on the inside of the valve, on the outside opening at the edge of the valve into an arch-like structure with thickened edges and sometimes triangular or rounded flaps, located under each 2–5 spines; density 3.9–4.2 in 10 μm. A single sessile rimoportula with a long conical tube on the outside of the valve, located in the ring of spines, and a labiate slit on the inside, oriented tangential to radial.</p><p>Found in: Narva and Kama Reservoirs, Unezhma River and Lake Okunevo (Karelia), Delingde and Taz rivers</p><p>(Western Siberia).</p></div>	https://treatment.plazi.org/id/03CA8782DF40C20EFF17FA54FED6FF50	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
03CA8782DF45C204FF17F8FAFCD6FE1C.text	03CA8782DF45C204FF17F8FAFCD6FE1C.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus lacustris (Genkal, Kulikovskiy, Glushchenko & Tseplik 2025) Genkal, Kulikovskiy, Glushchenko & Tseplik 2025	<div><p>Stephanoarcus lacustris (Klee &amp; Houk) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov. (Figs 31–36)</p><p>Basionym: Stephanodiscus lacustris Klee &amp; Houk in Houk et al. 2014. Fottea (Supplement) 14: 45, pl. 150: figs 1–12.</p><p>Synonyms: S. triporus var. volgensis sensu Genkal &amp; Korneva, 1990, Fig. 4 f, g; S . triporus var. volgensis sensu Genkal 1992, Table XII, 5, XIII, 2, 3; S. triporus sensu Genkal, 2013, Tab. I, 6; S. triporus sensu Genkal &amp; Trifonova, 2011, Tab. VI, 2, 3; S. triporus sensu Genkal et al., 2020, Tab. 63, 3, 4.</p><p>Description. Cells low cylindrical. Valves flat or with a slightly convex or concave center, 3.1–8.0 µm in diameter,</p><p>10–20 striae, 31–56 areolae in 10 µm (n = 21). Fascicles consist of 1 areola at the center and 2–4 areolae towards the valve edge. In the center of the valve the areolae are located irregularly, often there is one larger areola in the center and a single valve face fultoportula with 2–4 satellite pores. Small conical spines located on costae at the junction of valve face and mantle, density 20–23 in 10 μm. Marginal fultoportulae with 3 satellite pores on the inside of the valve, on the outside opening at the edge of the valve into an arch-like structure, located under each 2–5 spines; density approximately 3.9 in 10 μm. A single sessile rimoportula with a conical tube on the outside of the valve, located in the ring of spines, and a labiate slit on the inside, oriented tangential to radial.</p><p>Found in: Neva Bay, Rybinsk and Cheboksary Reservoirs.</p></div>	https://treatment.plazi.org/id/03CA8782DF45C204FF17F8FAFCD6FE1C	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
03CA8782DF4BC207FF17FCB8FEC2FEC4.text	03CA8782DF4BC207FF17FCB8FEC2FEC4.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus Genkal & Glushchenko & Tseplik & Kulikovskiy 2025	<div><p>Stephanoarcus gen. nov.</p><p>In the study that described the genus Praestephanos (Tuji et al. 2014), the authors identified the position of rimoportulae and marginal fultoportulae, as well as the pattern of areolae change, as defining characteristics for this genus that separate it from Cyclostephanos and Stephanodiscus . According to Tuji et al. (2014), in species of Praestephanos the rimoportulae are positioned on the same level as the spines, and the marginal fultoportulae and the change in pattern of areolae are close to the valve edge, below the rimoportulae. The authors transferred 3 species to this genus, however, they also show that P. triporus actually differs from the other two species of Praestephanos (Tuji et al. 2014, Fig. 3): in P. triporus the marginal fultoportulae are located at the very edge of the valve, and in P. suzukii and P. carconensis they are located approximately at 1/3 of the height of the valve mantle from the edge, with areolae present on the mantle lower than the marginal fultoportulae. This can also be seen in Praestephanos tokaiensis Kojima, K. Hattori, Ohtsuka &amp; Saito-Kato in Kojima et al. (2024: 294) and Praestephanos miensis Kojima &amp; Saito-Kato in Kojima et al. (2024: 299), in which a row of areolae can be seen below the level of marginal fultoportulae (Kojima et al. 2024). Moreover, P. triporus differs from other Praestephanos species by other features as well, such as different valve face relief, fascicles consisting of only 2–3 rows of areolae vs. 4–12 in other species, and the external openings of marginal fultoportulae forming arch-like structures and not tubes. Due to these differences, we are suggesting separating P. triporus, together with several similar species, into a new genus Stephanoarcus gen. nov., defined by the presence of arch-like structures (vestibules) around the marginal fultoportulae, the fascicles continuing from the valve face to the valve mantle without changes in areolae structure, and the marginal fultoportulae being positioned at the very edge of the valve mantle. A schematic representation of morphological structures on the valve mantle in Stephanoarcus gen. nov. is given in Fig. 37. Of the known Stephanodiscus species, S. vestibulis, S. lacustris and S. hashiensis also possess these characteristics, thus they are transferred into the new genus as well.</p><p>The arch-like structures around the marginal fultoportulae are quite diverse in their morphology (see schemes in Fig. 38). For example, in the type material of S. triporus arches with both wide and narrow openings were observed, sometimes with sector-shaped flaps visible on the sides of the arches (Kiss et al. 2013, Figs 8–9, 16); the same variability is shown in other studies (e.g., Tuji et al. 2014, Fig. 2C; Houk et al. 2014, Pl. 155 Figs 7–10; Genkal et al. 2020, Table 63: 1–6 and others). In our material, we observed arches with varying width (Figs 1, 3). S. vestibulis is also a widely known species; the type population possesses medium width arches with thickened edges (Håkansson et al. 1986, Fig. 6, 8), and also rounded (Gotoh et al. 1998, Figs 2–9) or triangular (this study, Fig. 22) flaps were observed. The more recently described S. lacustris and S. hashiensis are characterised by arches with rounded (Houk et al. 2014, Plate 150 Fig. 2) and sector-shaped (Houk et al. 2014, Plate 151 Figs 11–13) flaps respectively, with very narrow arches being typical for S. hashiensis . Given the high variability of this feature, the defining characteristic of Stephanoarcus gen. nov. is the presence of the arch-like structure, not its shape. However, in future studies it would be very beneficial to research the patterns of this variability by observing populations from different geographic locations and cells in different stages of the life cycle, as well as using molecular genetic methods to determine the taxonomic significance of this feature. Molecular data obtained by Tuji et al. (2014) showed the close relationship between S. triporus and P. suzukii, however, this conclusion is not supported by morphological analysis, and the issue requires further research.</p></div>	https://treatment.plazi.org/id/03CA8782DF4BC207FF17FCB8FEC2FEC4	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
03CA8782DF4BC204FF17FDCAFEC1FD58.text	03CA8782DF4BC204FF17FDCAFEC1FD58.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Stephanoarcus hashiensis (Genkal, Kulikovskiy, Glushchenko & Tseplik 2025) Genkal, Kulikovskiy, Glushchenko & Tseplik 2025	<div><p>Stephanoarcus hashiensis (H. Tanaka) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov.</p><p>Basionym: Stephanodiscus hashiensis H. Tanaka in Houk et al. 2014. Fottea (Supplement) 14: 45, pl. 151: figs 1–13; pl. 152: figs 1–7.</p><p>Stephanoarcus moraviensis (Houk, Klee &amp; H. Tanaka) Genkal, Kulikovskiy, Glushchenko &amp; Tseplik comb. nov. Basionym: Stephanodiscus moraviensis Houk, Klee &amp; H. Tanaka in Houk et al. 2014. Fottea (Supplement) 14: 46, pl. 153: figs 1–13; pl.</p><p>154: figs 1–6.</p></div>	https://treatment.plazi.org/id/03CA8782DF4BC204FF17FDCAFEC1FD58	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Genkal, Sergei;Glushchenko, Anton;Tseplik, Natalia;Kulikovskiy, Maxim	Genkal, Sergei, Glushchenko, Anton, Tseplik, Natalia, Kulikovskiy, Maxim (2025): A reinvestigation of Stephanodiscus triporus (Stephanodiscaceae, Mediophyceae) with the description of Stephanoarcus gen. nov. Phytotaxa 712 (1): 1-17, DOI: 10.11646/phytotaxa.712.1.1, URL: https://doi.org/10.11646/phytotaxa.712.1.1
