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Vijver, Bart Van De (2023): Staurosirella eruciformis, a new Staurosirella (Bacillariophyta) species from a historic sample from Scotland, UK. Phytotaxa 595 (3): 296-300, DOI: 10.11646/phytotaxa.595.3.4, URL: http://dx.doi.org/10.11646/phytotaxa.595.3.4

During a survey of diatoms present in tidal pools on the coasts of Livingston Island (South Shetland Islands), we found several populations, belonging presumably to the Antarctic endemic Craspedostauros laevissimus. Further analyses using light microscopy revealed that the populations show differences in stria density. Following scanning electron microscopy observations, only part of the investigated populations could be assigned to C. laevissimus, whereas the others are sufficiently morphologically different based on stria density and their cribrate areolae structure to be described as a new species: Craspedostauros confusus sp. nov. The new taxon is compared with known, morphologically similar, Craspedostauros taxa. The paper presents morphological and ecological data for both taxa discussed in the study. A detailed survey of the early Antarctic literature showed that the Craspedostauros taxa in Antarctica have convoluted taxonomic histories and that the new taxon has likely been hidden for long within the variability of C. laevissimus.

Orthoseira groenlandica Goeyers, Kochman-Kędziora & Van de Vijver, sp. nov. (Figs 1–30) Type:— GREENLAND, Qeqertarsuaq, sample DM27 (coll. date 27.VII.2002, 69°15’23.3”N / 53°30’26.5”W, leg. P. Ledeganck), holo-BR-4801! (Meise Botanic Garden, Belgium), iso- slide 428! (University of Antwerp, Belgium). The holotype is represented by Fig. 8. PhycoBank registration:—http://phycobank.org/103791 LM (Figs 1–22): Frustules cylindrical in girdle view, solitary or occasionally in pairs, with their valve faces connected (Figs 1–6, frustules in pairs not shown). Longer filaments of more than two connected frustules up to now not observed. Cells 15–25 μm, mantle height ca. 8 μm. Valves disc-shaped (Figs 7–22). Valve diameter (n=30): 10–35 μm. Valve surface flat, sloping abruptly at the valve face/mantle junction, visible in LM as a darker circular edge. Central area small, max. 1/5 of the total valve diameter, irregular in shape, hyaline, with often scattered areolae present between the carinoportulae. 2–3 (occasionally 4) large, rounded carinoportulae present. No relationship noted between number of carinoportulae and valve diameter. Striae on the mantle uniseriate, composed of densely packed irregular series of areolae, up to 25 in 10 μm. Valve face areolae large, arranged in radiate, uniseriate striae of variable length, 14–18 in 10 µm. Large, scattered marginal spines distinctly present at the valve face/mantle junction. No caverns, internal undulations or internal valves observed. Copulae number variable. (Figs 1–6). SEM (Figs 23–35): Cingulum composed of several broad, open copulae entirely covered with small siliceous papillae (Figs 23, 24) and bearing several irregularly arranged, often incomplete rows of small poroids (Figs 23, 24). Mantle shallow, often with a clear step halfway the valve mantle (Figs 25, arrow, 26) giving the abvalvar mantle edge a thickened appearance compared to the advalvar edge. Marginal pore fields absent. Mantle covered by an irregular pattern of flattened but thickened ridges, giving the entire mantle a dirty outlook. Ridges extending from the valve face onto the advalvar edge of the mantle, continuing into a scattered pattern of small siliceous plates (Figs 26, 26). Areolae visible between the small siliceous plates (Fig. 26). Valve face/mantle junction abruptly sloping with rounded edge (Figs 25, 26). Short, radiating ridges surrounding the entire valve margin (Figs 25–29). Short, robust, marginal spines irregularly scattered on the valve margin (Figs 25–32). Valve face flat (Figs 27–29), covered in the center by a dense pattern of irregular small and large siliceous plates, obscuring the carinoportulae (Figs 27–30). Radiating striae extending from the central area to the valve margin, composed of distinct, rimmed, rounded areolae. In oblique view, the marginal zone of the valve face presenting a dense, irregular pattern of shorter and longer, small spines and papillae between and around the areolae (Figs 30, 32). Internally, valve face flat, smooth (Fig. 33). Areolae appearing as small, rounded poroids (Figs 34, 35). Striae often interrupted by short, slit-like openings (Fig. 34, arrows). Carinoportulae unoccluded (Fig. 33), pit-like, ornamented with a rough pattern (Figs 34, 35). Several slit-like openings present between the carinoportulae (Figs 34, 35). Internal caverns not observed (Fig. 33). Ecology and associated diatom flora:—The sample was collected from wet (unidentified) terrestrial bryophytes, covered by cyanobacteria such as Phormidium sp., in a splash zone under an overhanging cliff from where water was continuously dripping on the soil and mosses. Water squeezed out of the mosses had a pH of 9 and a conductivity of 76 µS/cm and contained almost no nutrients (Van de Vijver, unpubl. res.). The diatom flora was entirely dominated by only a handful of species with Luticola arctica Levkov & Metzeltin (in Levkov et al. 2013: 67) and Humidophila perpusilla (Grunow 1860: 552) R.L. Lowe (2014: 358) as the most dominant species, and Stauroneis obtusa Lagerstedt (1873: 36) and Orthoseira groenlandica being frequent but not dominant, pointing to the aerophilic character of the environment., Published as part of Goeyers, Charlotte, Kochman-Kędziora, Natalia & Vijver, Bart Van De, 2023, Orthoseira groenlandica sp. nov., a new aerophilic diatom (Orthoseirales, Bacillariophyta) species from Greenland, pp. 81-89 in Phytotaxa 601 (1) on page 83, DOI: 10.11646/phytotaxa.601.1.6, http://zenodo.org/record/8129507, {"references":["Levkov, Z., Metzeltin, D. & Pavlov, A. (2013) Luticola and Luticolopsis. Diatoms of Europe 7: 1 - 698.","Grunow, A. (1860) Uber neue oder ungenugend gekannte Algen. Erste Folge, Diatomeen, Familie Naviculaceen. Verhandlungen der kaiserlich-koniglichen zoologisch-botanischen Gesellschaft in Wien 10: 503 - 582.","Lowe, R. L., Kociolek, P., Johansen, J. R., Van de Vijver, B., Lange-Bertalot, H. & Kopalova, K. (2014) Humidophila gen. nov., a new genus for a group of diatoms (Bacillariophyta) formerly within the genus Diadesmis: species from Hawai'i, including one new species. Diatom Research 29 (4): 351 - 360. https: // doi. org / 10.1080 / 0269249 X. 2014.889039","Lagerstedt, N. G. W. (1873) Sotvatens-Diatomaceer fran Spetsbergen och Beeren Eiland. Bihang till Kongliga Svenska Vetenskaps- Akademiens Handlingar 1 (14): 1 - 52."]}

Goeyers, Charlotte, Kochman-Kędziora, Natalia, Vijver, Bart Van De (2023): Orthoseira groenlandica sp. nov., a new aerophilic diatom (Orthoseirales, Bacillariophyta) species from Greenland. Phytotaxa 601 (1): 81-89, DOI: 10.11646/phytotaxa.601.1.6, URL: http://dx.doi.org/10.11646/phytotaxa.601.1.6

During a survey of some exsiccata samples from Rabenhorst’s Die Algen Sachen’s und Europa’s, two Staurosirella taxa that could not be identified using the currently available literature were observed in a sample from the Swiss Alps, collected in 1863 CE. The two taxa occurred together with a large population of S. neopinnata and were studied using detailed light and scanning electron microscopy. Based on the obtained observations on their morphology, and after comparing both taxa with all currently known Staurosirella and some Staurosira species, both are described as new. Staurosirella coutelasiana Van de Vijver sp. nov. is characterized in having a linear-lanceolate to lanceolate, isopolar valve outline with small apical pore fields on both apices. The second new species, S. minutissima Van de Vijver sp. nov., is a small-celled Staurosirella species and possesses short lineolae, an almost flat valve surface and small apical pore fields. Both species are extensively illustrated and discussed. Their ecological preferences are derived from the associated diatom flora in the sample and point to oligotrophic, calcium-carbonate rich, oligosaprobic conditions.

Pseudostaurosira ellipticolanceolata André, Sabbe & Van de Vijver, sp. nov. (Figs 1–21 LM, 22–28 SEM) Valves lanceolate to linear-lanceolate in larger specimens, becoming elliptic-lanceolate to elliptic in smallest valves (Figs 1–21). Valve margins parallel in longer valves to distinctly convex in the smaller range of the cell diminution series. Apices very weakly protracted (Figs 1–3), subrostrate, to non-protracted, broadly rounded in smaller specimens. Valve dimensions (n=40): valve length 4–20 µm, valve width 3.5–4.0 µm. Sternum broad in the largest specimens, becoming moderately broad in smaller valves, lanceolate. Striae uniseriate, parallel to weakly radiate throughout the entire valve length, 16–18 in 10 µm, composed of 1–2, rarely 3 areolae, on valve face (Figs 22, 25), and 1–2 areolae on valve mantle. Areolae at valve face/ mantle junction markedly larger, becoming smaller towards sternum (Figs 22, 24). Mantle areolae separated from those on valve face by short linking spines (Figs 22, 25). Interdigitating spines originating from vimines, solid, spatulate with broad tip (but probably broken and eroded in all observed specimens) (Fig. 23, white arrows). Areola occlusions eroded, vestiges partly visible in some areolae, suggesting volate occlusion type (Figs 27, 28, black arrows). Apical pore field reduced to a handful of very small pores (Figs 27, 28, white arrows). Internally, sternum flat with raised virgae between striae (Fig. 26). Girdle structure not observed due to severe erosion of the frustules. Mantle plaques not observed (but unclear whether being a result of valve erosion). Type:— BELGIUM. Burchtstraat, Aardenburg, sediment core, sample 85, C. André, 1 st March 2019 (holotype slide BR-4776= Fig. 6. Isotype slide 421, University of Antwerp, Belgium). PhycoBank registration:— http://phycobank.org/103600 Ecology and associated diatom flora:— Pseudostaurosira ellipticolanceolata has a relative abundance of almost 10% in the type sample. This sample is part of a clay layer from a sediment core taken at the edge of a ditch around the Roman castellum at Aardenburg, which most likely received marine input via a tidal channel and freshwater input from an inland river, possibly the river Ee. The clay layer dates back to the Holocene, with the first indications pointing to a possible age between the 4 th and 10 th century AD (André, unpubl. data). Other dominant species include Epithemia adnata (Kützing 1833: 544) Brébisson (1838: 16), Staurosira cf. venter (Ehrenberg 1854: 13, pl. XIV) Cleve & J.D.Möller (1879: no. 242) sensu Lange-Bertalot et al. (2017), Eunotia minor (Kützing 1844: 39) Grunow (in Van Heurck 1881: pl. 33: figs 20, 21) and Cymatosira belgica Grunow (in Van Heurck 1881: pl. 45: figs 38–41). This diatom flora points to a brackish, eutrophic environment (Lange-Bertalot et al. 2017). Epithemia adnata is typically epiphytic and may point to the presence of submerged vegetation, but is also salinity-tolerant and often occurs in aquatic conditions with higher electrolyte contents (Lange-Bertalot et al. 2017). Cymatosira belgica is considered a marine tychoplanktonic species, typically observed in tidal inlets and large tidal channels (Vos & de Wolf, 1988). The presence of Eunotia minor is more difficult to explain but most likely the result of the influx of foreign material. Unfortunately, the taxonomic identity of S. cf. venter is too unclear to draw ecological conclusions from their presence in the sample. Taxonomic comments:— Morales et al. (2021) discuss a large number of Pseudostaurosira species that are known worldwide when they described several new species from Bolivia. Based on valve outline and valve dimensions, the new P. ellipticolanceolata shows some similarity with the group of Pseudostaurosira subsalina (Hustedt) E. Morales (2005: 115) and P. polonica (M.Witak & Lange-Bertalot in Witkowski et al. 1995: 736) E.Morales & M.B.Edlund (2003: 235). Pseudostaurosira occulta E.Morales, C.E.Wetzel & Ector (2021: 40) shows comparable valve dimensions (length 7–35 µm, width 3.5–4.0 µm) and, at least in the longer range of the size diminution series, a comparable valve outline with almost parallel margins. However, differences can be noted in the shape of the apices (squarish in P. occulta, more broadly rounded in P. ellipticolanceolata), stria density (14–16 in 10 µm in P. occulta versus 16–18 in 10 µm in P. ellipticolanceolata) and stria structure. In P. occulta, striae are usually composed of 3–4 areolae whereas striae with 3 areolae are rather rare in P. ellipticolanceolata. Due to the high degree of erosion, it was not possible to comment on the structure and shape of the apical pore field (covered by an external flap in P. occulta) and the linking spines. Pseudostaurosira subsalina has broader valves (valve width 4.0–5.5 µm), a lower stria density (13–14 in 10 µm), a higher number of areolae per stria, a larger apical pore field (compared to the reduced pore field in P. ellipticolanceolata), and a broader transition step between valve face and mantle, excluding possible conspecificity (Cejudo-Figueiras et al. 2011). Pseudostaurosira zolitschkae M.L.García et al. (in Garcia et al. 2021: 265) differs in having acutely protracted valve apices and a much lower stria density (11–14 in µm) (García et al. 2021). Other taxa in this group differ by the shape of the areolae (P. polonica has only one, transapically elongated areola per striae), valve dimensions or valve outline. Pseudostaurosira oliveraiana Grana et al. (2018: 63) has longer valves (19–39 µm) and typically capitate to rostrate apices throughout its entire cell diminution series (Grana et al. 2018, figs 2–15). Smaller taxa such as P. alvareziae Cejudo-Figueiras, E.Morales & Ector (in Cejudo-Figueiras et al. 2011: 69) and P. oblonga E.Morales, C.E.Wetzel & Ector (2021: 41) have a more elliptic to elliptic-lanceolate valve outline with strictly convex margins, with elongated, more linear-lanceolate valves so far not observed for these species, in contrast to P. ellipticolanceolata that shows a more linear outline with parallel margins in the longer specimens., Published as part of André, Coralie, Sabbe, Koen & Vijver, Bart Van De, 2023, Pseudostaurosira ellipticolanceolata, a new araphid diatom (Bacillariophyta) from Flanders, Belgium, pp. 83-86 in Phytotaxa 591 (1) on pages 83-85, DOI: 10.11646/phytotaxa.591.1.10, http://zenodo.org/record/7784131, {"references":["Kutzing, F. T. (1833) Synopsis diatomearum oder Versuch einer systematischen Zusammenstellung der Diatomeen. Linnaea 8: 529 - 620. https: // doi. org / 10.5962 / bhl. title. 65634","Brebisson, A. de (1838) Considerations sur les diatomees et essai d'une classification des genres et des especes appartenant a cette famille, par A. de Brebisson, auteur de la Flore de Normandie. Falaise & Paris: Bree l'Ainee Imprimeur-Libraire, Meilhac. pp. 1 - 20. https: // doi. org / 10.5962 / bhl. title. 64353","Ehrenberg, C. G. (1854) Mikrogeologie. Einundvierzig Tafeln mit uber viertausend grossentheils colorirten Figuren, Gezeichnet vom Verfasser. Leipzig: Verlag von Leopold Voss. pp. 1 - 31, 40 pls [Taf. I - XXXX].","Lange-Bertalot, H., Hofmann, G., Werum, M. & Cantonati, M. (2017) Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with updated taxonomy and added species. Koeltz Botanical Books, Schmitten- Oberreifenberg, 942 pp. [Cantonati, M., Keely, M. & Lange-Bertalot, H. (eds.)]","Kutzing, F. T. (1844) Die Kieselschaligen Bacillarien oder Diatomeen. Nordhausen. pp. 1 - 152. https: // doi. org / 10.5962 / bhl. title. 64360","Van Heurck, H. (1881) Synopsis des Diatomees de Belgique Atlas. Anvers: Ducaju et Cie. pls XXXI - LXXVII [31 - 77].","Vos, P. C. & de Wolf, H. (1988) Methodological aspects of paleo-ecological diatom research in coastal areas of the Netherlands. Geologie en Mijnbouw 67: 31 - 40.","Morales, E. A., Wetzel, Z. E. & Ector, L. (2021) New and poorly known´araphid \" diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in´araphid \" diatom taxonomy. PhytoKeys 187: 23 - 70. https: // doi. org / 10.3897 / phytokeys. 187.73338","Morales, E. A. (2005) Observations of the morphology of some known and new fragilarioid diatoms (Bacillariophyceae) from rivers in the USA. Phycological Research 53 (2): 113 - 133. https: // doi. org / 10.1111 / j. 1440 - 1835.2005. tb 00363. x","Witkowski, A., Lange-Bertalot, H. & Witak, M. (1995) Diatom taxa of unusual frustule structure belonging to the genus Fragilaria. Fragmenta Floristica et Geobotanica 40 (2): 729 - 741.","Cejudo-Figueiras, C., Morales, E. A., Wetzel, C. E., Blanco, S., Hoffmann, L. & Ector, L. (2011) Analysis of the type of Fragilaria construens var. subsalina (Bacillariophyceae) and description of two morphologically related taxa from Europe and the United States. Phycologia 50 (1): 67 - 77. https: // doi. org / 10.2216 / 09 - 40.1","Garcia, M. L., Bustos, S., Villacis, L. A., Laprida, C., Mayr, C., Moreno, P. I., Maidana, N. I. & Morales, E. A. (2021) New araphid species of the genus Pseudostaurosira (Bacillariophyceae) from southern Patagonia. European Journal of Phycology 56 (3): 255 - 272. https: // doi. org / 10.1080 / 09670262.2020.1813810","Grana, L., Morales, E. A., Maidana, N. I. & Ector, L. (2018) Two new species of Staurosira and Pseudostaurosira (Bacillariophyta) from the highlands of Argentina (south-central Andes) and two new nomenclatural combinations. Phytotaxa 365 (1): 60 - 72. https: // doi. org / 10.11646 / phytotaxa. 365.1.2"]}

Brachysira heteropolaris Van de Vijver sp. nov. (Figs 1 –26 LM) Valves heteropolar, clavate. Valve outline lanceolate with convex margins. Apices not protracted, acutely rounded. At footpole slightly more elongated than at headpole. Valve dimensions (n=40): length 18–35 µm, width 6–8 µm, largest width above the valve middle. Axial area very narrow, linear. Two longitudinal ridges bordering the axial area, running from valve apices to central area. Central area usually small, rounded to elliptical, and raised. Occasionally valves with slightly larger central areas observed (see for instance Figs 7, 11). Raphe filiform, raphe branches straight with indistinct, simple central raphe endings. Striae radiate throughout the entire valve length, well discernible in LM, 28–30 in 10 µm. Irregular, short ridges present crossing the striae (e.g. Figs 1, 4, 8 & 14). Type:— UNITED KINGDOM. Loch Canmor 2 (=Loch Kinord), Aberdeenshire 2, Scotland, prep. Weissflog, slide IX-18-A 8 in BR! (holotype slide BR-4777 = Fig. 5). Registration: —http://phycobank.org/103608 Etymology:—The specific epithet “ heteropolaris ” refers to the heteropolar valve outline. Ecology & associated diatom flora:—The Weissflog slide was prepared based on material from Loch Canmor. In the Van Heurck collection in BR (Belgium), several slides from Loch Canmor are conserved, two of them labelled “Loch Canmor 2 – Aberdeenshire – Schottland ” (slides IX-18-A8 &A10). Loch Canmor, nowadays called Loch Kinord is a small, freshwater lake at Muir of Dinnet (Aberdeenshire, Scotland), a few kilometers east of the village of Ballater. This shallow (max. 2m depth) freshwater loch is a part of the Muir of Dinnet National Nature Reserve and an important resting place for wintering birds. The loch is characterised as being oligotrophic and low-alkaline (Bennion et al. 2004, Lang et al. 2012). The diatom flora in the slide is characterised by a high biodiversity. Dominant species include Brachysira follis, B. brebissonii, B. confusa, Encyonema neogracile Krammer (1997a: 177), Encyonopsis cesatii var. geitleri Krammer (1997b: 154), Frustulia saxonica Rabenhorst (1853: 50), Gomphonema coronatum Ehrenberg (1840: 211), G. lagerheimii A. Cleve (1895: 22), Tabellaria fenestrata (Lyngbye 1819: 180) Kützing (1844: 127), and several Eunotia and Pinnularia species. This species composition reflects dystrophic to oligo-trophic, circumneutral to acidic, oligosaprobic conditions (Lange-Bertalot & Moser 1994, Lange-Bertalot et al. 2017). Although most species in the slide are acidophilous, several species preferring calcium-carbonate enriched conditions such as Brachysira styriaca, Eucocconeis flexella (Kützing 1844: 80) F. Meister (1912: 95), and Navicula radiosa Kützing (1844: 91) are present, though in low abundances. Some of these, such as N. radiosa, could, however, also survive in low-alkaline conditions, though not in high abundances (Lange-Bertalot 2001)., Published as part of Vijver, Bart Van De, 2023, Brachysira heteropolaris, a new diatom (Brachysiraceae, Bacillariophyta) species observed in an historic Weissflog slide from Scotland (UK), pp. 47-52 in Phytotaxa 587 (1) on pages 48-49, DOI: 10.11646/phytotaxa.587.1.6, http://zenodo.org/record/7710708, {"references":["Bennion, H., Fluin, J. & Simpson, G. L. (2004) Assessing eutrophication and reference conditions for Scottish freshwater lochs using subfossil diatoms. Journal of Applied Ecology 41: 124 - 138. https: // doi. org / 10.1111 / j. 1365 - 2664.2004.00874. x","Lang, P., Krokowski, J., Ross, N. & Doughty, R. (2012) The rare green alga Pediastrum privum (Chlorophyta, Sphaeropleales) in a Scottish kettle loch: new to British freshwaters. The Glasgow Naturalist 25: 139 - 142.","Krammer, K. (1997 a) Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 1. Allgemeines und Encyonema Part. Bibliotheca Diatomologica 36: 1 - 382.","Krammer, K. (1997 b) Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema Part., Encyonopsis und Cymbellopsis. Bibliotheca Diatomologica 37: 1 - 469.","Rabenhorst, L. (1853) Die Susswasser-Diatomaceen (Bacillarien.): fur Freunde der Mikroskopie. pp. 1 - 72. https: // doi. org / 10.5962 / bhl. title. 8348","Ehrenberg, C. G. (1840) Characteristik von 274 neuenArten von Infusorien. Bericht uber die zur Bekanntmachung geeigneten Verhandlungen der Koniglich-Preussischen Akademie der Wissenschaften zu Berlin 1840: 197 - 219.","Cleve, A. (1895) On recent freshwater diatoms from Lule Lappmark in Sweden. Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar 21 (Afh. III, 2): 1 - 44.","Lyngbye, H. C. (1819) Tentamen hydrophytologiae danicae continens omnia hydrophyta cryptogama Daniae, Holsatiae, Faeroae, Islandiae, Groenlandiae hucusque cognita, systematice disposita, descripta et iconibus illustrata, adjectis simul speciebus norvegicis. pp. [i] - xxxii, [1] - 248, 70 pls. Hafniae [Copenhagen]: typis Schultzianis, in commissis Librariae Gyldendaliae. https: // doi. org / 10.5962 / bhl. title. 6079","Kutzing, F. T. (1844) Die Kieselschaligen Bacillarien oder Diatomeen. Nordhausen. pp. 1 - 152. https: // doi. org / 10.5962 / bhl. title. 64360","Lange-Bertalot, H. & Moser, G. (1994) Brachysira. Monographie der Gattung und Naviculadicta nov. gen. Bibliotheca Diatomologica 29: 1 - 212.","Lange-Bertalot, H., Hofmann, G., Werum, M. & Cantonati, M. (2017) Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with updated taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books; p. 1 - 942.","Meister, F. (1912) Die Kieselalgen der Schweiz. Beitrage zur Kryptogamenflora der Schweiz. Materiaux pour la flore cryptogamique suisse. Vol. IV, fasc. 1. pp. [i] - vi, [1] - 254.","Lange-Bertalot, H. (2001) Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. Diatoms of Europe 2: 1 - 526."]}

During an evaluation of the diatom diversity and water quality of a small brook near Morogoro (Tanzania), an unknown Planothidium species was observed that could not be identified using the currently available literature. The past 10 years, a large number of Planothidium species has been revised resulting in a better characterisation of some well-known taxa such as P. lanceolatum (Brébisson ex Kützing 1846: 247) Lange-Bertalot (1999: 287), P. frequentissimum (Lange-Bertalot 1993: 4) Lange-Bertalot (1999: 282) and P. delicatulum (Kützing 1844: 75) Round & Bukhtiyarova (1996: 353), but also in the description of a lot of new species (Compère & Van de Vijver 2009, Jahn et al. 2017, Kulaš et al. (2020), N’Guessan et al. 2014, Stancheva 2019, Stancheva et al. 2020, Van de Vijver et al. 2013, 2018, Wetzel et al. 2013, 2014, 2019). Several of these studies dealt with Planothidium species from the African Continent. Compère & Van de Vijver (2009) analysed and illustrated the type material of P. engelbrechtii (Cholnoky 1955: 16) Round & Bukhtiyarova (1996: 353), whereas N’Guessan et al. (2014) discussed the morphology and taxonomic history of two species formerly described by Carter & Denny in 1982: P. miotum (J.R.Carter & Denny 1982: 286) Lange-Bertalot (1999: 278) & P. piaficum (J.R.Carter & Denny 1982: 286) C.E.Wetzel & Ector (in N’Guessan et al. 2014: 460), completed with the description of P. comperei C.E.Wetzel et al. (in N’Guessan et al. 2014: 456), a new Planothidium species from Ivory Coast.

Planothidium africanum Van de Vijver, Gogne, Hoogsteyns, Van de Velde, Vlaminck, Kabota, Teunen & C.E.Wetzel sp. nov. (Figs 1–28 LM, 29–35 SEM) Valves lanceolate (in the largest specimens) to elliptic-lanceolate with distinctly convex margins and protracted, rostrate but truncated apices. Valve dimensions (n=40): length 11–25 μm, width 5.5–6.5 μm. Rapheless valve (Figs 1–14, 29, 30, 33 & 35): Axial area usually narrow, straight, linear, occasionally weakly lanceolate and broadening near the central area. Irregularly shaped, shallow depressions present in both central and axial area (Figs 29, 33). Central area with a unilateral large horseshoe-shaped hyaline area. Cavum distinctly visible, internally passing over the neighboring striae (Figs 30, 35). Striae on the opposite site only weakly to almost shortened. Striae parallel to weakly radiate near the central area, becoming more radiate near the apices, 15–16 in 10 µm. Striae multiseriate, composed of three rows of small, rounded areolae at the valve margins, becoming biseriate towards the axial area (Fig. 29, 33). On the mantle, irregular groupings of small, rounded areolae present, continuing the valve face striae on the mantle (Fig. 33). Internally, striae located in deep grooves (Fig. 30). Raphe valve (Figs 15–28, 31, 32 & 34): Axial area very narrow, linear, not widening towards the central area. Central area asymmetrical, rectangular to slightly wedgeshaped, bordered on each side by 2–3 shortened striae, whereas on the opposite side, striae either lacking or extremely shortened. Raphe branches straight with expanded, drop-like central raphe pores (Fig. 31). Terminal raphe fissures unilaterally deflected (Fig. 31). Striae weakly radiate throughout the entire valve, 14–16 in 10 μm. Internally, central nodule clearly raised (Fig. 32). Internal central raphe endings weakly deflected into opposite directions, terminating onto the central nodule (Fig. 32). Internally, striae located in broad, deep grooves (Fig. 32). Cingulum composed of multiple open girdle bands (Fig. 34). Type:— TANZANIA. Morogoro, sample L10 stone, coll. date VII.2022, leg. Van de Velde (holotype slide BR-4778= Fig. 6, isotype slide 422, University of Antwerp, Belgium). PhycoBank registration: — www.PhycoBank.org/103609 Ecology & associated diatom flora:— Sample L10 Stone (S 06° 49’ 00.1” / E 037° 42’ 56.8”) was collected from some submerged stones in a small, shallow (Navicula species [N. rostellata Kützing (1844: 95), N. schroeteri Meister (1932: 38), N. symmetrica R.M. Patrick (1944: 5)], Achnanthidium exiguum (Grunow in Cleve & Grunow 1880: 21) Czarnecki (1994: 157), Cocconeis cf. euglypta, Planothidium africanum, P. rostratum (Østrup 1903: 35) Lange-Bertalot (1999: 279), several (non-identified) Gomphonema species, and Geissleria cf. decussis with lower numbers of Seminavis strigosa (Hustedt 1949: 44) Danielidis & Economou-Amilli (in Danieldis & Mann 2003: 30), Halamphora sp. and Pleurosigma salinarum (Grunow 1878: 116) Grunow (in Cleve & Grunow 1880: 54). Based on Lange-Bertalot et al. (2017) and Taylor et al. (2007), this diatom flora is typical for eutrophic, freshwater with higher electrolyte content to even brackish, and β- to α-mesosaprobic conditions, pointing to a high degree of pollution. Taxonomic comments:— Table 1 lists the morphometric features of several similar Planothidium species. Planothidium africanum has a distinct cavum, excluding several species bearing a comparable valve outline but with a sinus from being conspecific. Planothidium californicum Stancheva & N.Kristan (in Stancheva et al. 2020: 8) has a similar valve outline and similar valve dimensions, but lacks the typical cavum and hence can be relatively easily separated from the new species. Planothidium dubium (Grunow in Cleve & Grunow 1880: 23) Round & Bukhtiyarova (1996: 352) and P. reichardtii Lange-Bertalot & Werum (in Werum & Lange-Bertalot 2004: 172) have a similar elliptic-lanceolate valve outline with truncated, rostrate apices and an asymmetrical central area in the raphe-bearing valve. But both taxa also lack the distinct cavum structure excluding hence all conspecificity. The African species discussed in N’Guessan et al. (2014) sufficiently differ not to be confused with P. africanum. Planothidium comperei shows the highest resemblance based on its valve outline, although most valves have more convex valve margins. The stria structure of the rapheless valve also shows some similarity with the multiseriate nature of the striae at the valve margins becoming biseriate near the axial area. But the species can be separated from P. africanum in having an almost symmetrical central area in the raphe-bearing valve with a more radiate striation pattern, contrary to P. africanum having more parallel striae and a distinctly asymmetrical central area with on one side an almost complete lack of (or very shortened) striae. The most similar species is P. incuriatum C.E.Wetzel, Van de Vijver & Ector, split off from P. biporomum (M.H. Hohn & Hellerman 1963: 273) Lange-Bertalot (1999: 275) in 2013. Most likely, P. africanum, P. incuriatum and P. biporomum are close to each other, given a similar shape in cavum structure, a similar stria structure with a multiseriate base at the valve margin and a biseriate part at the axial area, and similar shallow markings in the axial and central area. However, Planothidium incuriatum has a more elongated, slender valve outline with more protracted apices, a symmetrical central area in the raphe-bearing valves (contrary to the distinctly asymmetrical central area in P. africanum) and slightly wider valves (6.5–7.0 µm versus 5.5–6.5 µm in P. africanum). The striae in the rapheless valve of P. africanum have a distinct grouping of 3 series of areolae at the valve margin, a feature not observed in P. incuriatum that have a very faint third series of areolae at the margin (see for instance Wetzel et al. 2003, fig. 51). This grouping is also visible in the mantle areolae (Fig. 33). Finally, other rostrate, cavum-bearing taxa such as P. rostratum (present in the same sample as P. africanum) and P. rostratoholarcticum Lange-Bertalot & Bąk (in Bąk & LangeBertalot 2014: 354) differ in having multiple slit-like grooves in their axial and central area, so far not observed in P. africanum. Contrary, P. africanum possesses an irregular pattern of small, shallow depressions in the axial area, not seen in P. rostratum and P. rostratoholarcticum. Wetzel et al. (2019) discuss several small-celled cavum-bearing Planothidium species such as P. frequentissimum but they can all be separated based on their valve dimensions (usually shorter and/or narrower), shape of the apices (typically broadly rounded, hardly protracted in P. frequentissimum) and valve outline, most of them being more strictly lanceolate instead of the elliptic-lanceolate valves observed in P. africanum., Published as part of Vijver, Bart Van De, Gogne, Britt, Hoogsteyns, Gabrielle, Velde, Levente Van De, Vlaminck, Luna, Kabota, Sija A., Teunen, Lies & Wetzel, Carlos E., 2023, Planothidium africanum sp. nov., a new freshwater diatom (Bacillariophyta) species from Tanzania, pp. 281-286 in Phytotaxa 585 (4) on pages 282-284, DOI: 10.11646/phytotaxa.585.4.4, http://zenodo.org/record/7703860, {"references":["Kutzing, F. T. (1844) Die Kieselschaligen Bacillarien oder Diatomeen. Nordhausen, pp. [i-vii], [1] - 152.","Meister, F. (1932) Kieselalgen aus Asien. Gebruder Borntraeger, Berlin, pp. [1] - 56.","Patrick, R. M. (1944) Estudo Limnologico e Biologico das Lagoas da regiao Litoranea Sul-Riograndense II. Some New Diatoms from the Lagoa dos Quadros. Boletim do Museu Naciona, nova serie, botanica 2: 1 - 6.","Cleve, P. T. & Grunow, A. (1880) Beitrage zur Kenntniss der arctischen Diatomeen. Kongliga Svenska Vetenskaps-Akademiens Handlingar 17 (2): 1 - 121.","Czarnecki, D. B. (1994) The freshwater diatoms culture collection at Loras College, Dubuque, Iowa. In: Proceedings of the 11 th International Diatom Symposium. Memoirs of the California Academy of Sciences 17: 155 - 174.","Ostrup, E. (1903) Freshwater diatoms. In Flora of Koh Chang. Part VII. Contributions to the knowledge of the Gulf of Siam. Preliminary Report on Botany. Results Danish Expedition to Siam (1899 - 1900). Botanisk Tidsskrift 25 (1): 28 - 41.","Lange-Bertalot, H. (1999) Neue Kombinationen von Taxa aus Achnanthes Bory (sensu lato). Iconographia Diatomologica 6: 270 - 283.","Hustedt, F. (1949) Diatomeen von Sinai-Halbinsel und aus dem Libanon-Gebiet. Hydrobiologia 2: 24 - 55.","Grunow, A. (1878) Algen und Diatomaceen aus dem Kaspischen Meere. In: Schneider, O. (Ed.) Naturwissenschaftliche Beitrage zur Kenntnis der Kaukasuslander, auf Grund seiner Sammelbeute. Dresden Burdach, Dresden, pp. 98 - 132.","Lange-Bertalot, H., Hofmann, G., Werum, M. & Cantonati, M. (2017) Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with updated taxonomy and added species. Koeltz Botanical Books, Schmitten- Oberreifenberg, 942 pp.","Taylor, J. C., Harding, W. R. & Archibald, C. G. M. (2007) An Illustrated Guide to Some Common Diatom Species from South Africa An Illustrated Guide to Some Common Diatom Species from South Africa. WRC Report No TT 282 / 07. Water Research Commission, Pretoria, pp. 1 - 178 pls.","Stancheva, R., Kristan, N. V., Kristan, W. B, III & Sheath, R. G. (2020) Diatom genus Planothidium (Bacillariophyta) from streams and rivers in California, USA: diversity, distribution and autecology. Phytotaxa 470 (1): 1 - 30. https: // doi. org / 10.11646 / phytotaxa. 470.1.1","Round, F. E. & Bukhtiyarova, L. (1996) Four new genera based on Achnanthes (Achnanthidium) together with a re-definition of Achnanthidium. Diatom Research 11 (2): 345 - 361. https: // doi. org / 10.1080 / 0269249 X. 1996.9705389","Werum, M. & Lange-Bertalot, H. (2004) Diatoms in springs from Central Europe and elsewhere under the influence of hydrologeology and anthropogenic impacts. Iconographia Diatomologica 13: 3 - 417.","N'Guessan, K. R., Wetzel, C. E. Ector, L., Coste, M., C. Cocquyt, C., Van de Vijver, B., Yao, S. S., Ouattara, A., Kouamelan, E. P. & Tison- Rosebery, J. (2014) Planothidium comperei sp. nov. (Bacillariophyta), a new diatom species from Ivory Coast. Plant Ecology and Evolution 147 (3): 455 - 462. https: // doi. org / 10.5091 / plecevo. 2014.981","Hohn, M. H. & Hellerman, J. (1963) The taxonomy and structure of diatom populations from three eastern North American rivers using three sampling methods. Transactions of the American Microscopical Society 82 (3): 250 - 329.","Wetzel, C. E., Van de Vijver, B., Hoffmann, L. & Ector, L. (2013) Planothidium incuriatum sp. nov. a widely distributed diatom species (Bacillariophyta) and type analysis of Planothidium biporomum. Phytotaxa 138 (1): 43 - 57. https: // dx. doi. org / 10.11646 / phytotaxa. 138.1.6","Wetzel, C. E., Van de Vijver, B., Blanco, S. & Ector, L. (2019) On some common and new cavum-bearing Planothidium (Bacillariophyta) species from freshwater. Fottea 19 (1): 50 - 89. https: // doi. org / 10.5507 / fot. 2018.016","Bak, M. & Lange-Bertalot, H. (2014) Four small-celled Planothidium species from Central Europe proposed as new to science. Oceanological and Hydrobiological Studies 43 (4): 346 - 359. https: // doi. org / 10.2478 / s 13545 - 014 - 0152 - 9"]}

Craspedostauros laevissimus (West & G.S.West 9: 8) Sabbe (00: 5) (Figs – 8, 7, 9– 7, 80–85) LM observations (Figs – 8, 7, 80–85):— Frustules rectangular, lanceolate in girdle view with weakly convex margins (Figs 7, 8), constricted in the middle (i.e. biarcuate), with numerous copulae (Fig. 18). Longest valves linear (Figs 80, 83, 85), linear-lanceolate, smaller valves becoming elliptic-lanceolate (Figs 4, 13, 15, 27). Apices broadly rounded (Figs 4, 15, 27), to almost cuneate (Figs 2, 3, 13). Valve margins in the middle ranging from occasionally almost straight (Fig. 83) to, usually, weakly (Figs 3, 5) to moderately (Figs 4, 9) convex. Valve dimensions (n = 26): valve length 20–42 µm, valve width 4.5–7.0 µm. Occasionally, weakly silicified valves, probably in state of formation, and easily “squashed” on the slides, appear to have a larger valve width (see for instance Figs 81, 82, 84). Axial area very narrow, linear. Central area variable in size, from very narrow (Figs 9, 11), almost rectangular (Figs 3, 16) to bow-tie-shaped fascia, widening towards the margin (Figs 2, 4, 5, 27). Raphe filiform, slightly curved to straight, with enlarged central raphe endings, and elongated, unilaterally bent, terminal raphe fissures. Striae fine, parallel, occasionally very weakly radiate in the middle, 28–30(32) in 10 µm. Areolae not or occasionally slightly individually discernible in LM. SEM observations (Figs 9– 7, 86–87):— Externally, valve face curving into a deep mantle (Figs 29, 38). Raphe almost straight (Figs 29, 32, 36, 39) or sometimes weakly undulating (Fig. 35). Central raphe endings weakly curved and enlarged (Figs 29–30, 32–33, 35, 37), occasionally straight and only weakly expanded (Figs 39–40). At the apices, axial area triangularly widening, forming a silica flap (Figs 38, 41) on one side covering the terminal raphe fissures. Fissures continuing shortly onto the mantle (Figs 31, 34, 35, 38, 39, 41), clearly unilaterally bent (Figs 35, 36) to weakly hooked (Fig. 38). Striae uniseriate, composed of cribrate areolae of almost equal size (Figs 30, 35, 39, 40, 45) to slightly larger near the axial area (Figs 37, 40, 41). Larger areolae, apparently formed by merging two adjacent areolae occasionally present near the axial area (Figs 31, 87, arrows). Areolae continuing around the apices (Figs 31, 34, 38). Cribra composed of usually four (Figs 34, 37, 40, 42), rarely five (Figs 33, 34, 40) peripheral pores, although very rarely, up to 6–7 very small peripheral pores were observed (Fig. 41), or very occasionally only 1–3 (Fig. 45). In general, areolae near the axial area more complex, with more peripheral pores, whereas areolae on the rest of the valve face simplified having a lower number of peripheral pores (Figs 40, 45). Central cribrum pores usually single or absent (Figs 30, 37, 40), occasionally 2–3 (Figs 31, 33, 34, 41). Areolae uniformly distributed over the valve face, ca. 40 in 10 µm. Internally, areolar openings square to rectangular (Figs 46, 47), to almost rounded (Figs 43, 45). Internal raphe branches straight, located on a distinctly raised sternum. Central raphe endings terminating onto double helictoglossae (Figs 43, 45, 46). Stauros narrow, located on a wider hyaline fascia (Figs 43–46). Terminal raphe endings finish onto broad helictoglossae (Figs 46, 47). Ecology and associated diatom flora:— The species was often found in the epilithon of tidal pools at Hannah Point (samples 11 and 13, and LT10), having variable salinity levels between 11.5 and 33.7 (Table 2), but it was most abundant in sample 13. The diatom flora of this sample included Melosira spp. and several unidentified Navicula taxa in larger numbers., Published as part of Zidarova, Ralitsa, Haan, Myriam De, Ivanov, Plamen, Hineva, Elitsa & Vijver, Bart Van De, 2022, The genus Craspedostauros E. J. Cox (Bacillariophyta) on the coasts of Livingston Island, Maritime Antarctica, pp. 1-24 in Phytotaxa 572 (1) on pages 4-7, DOI: 10.11646/phytotaxa.572.1.1, http://zenodo.org/record/7305672

Craspedostauros confusus Zidarova, M.de Haan, P.Ivanov, Hineva & Van de Vijver sp. nov. (Figs 9– 6, 8, 8–56) Description LM observations (Figs 9– 6, 8):— Frustules lanceolate in girdle view with convex, rarely weakly constricted (and hence biarcuate) margins, bearing numerous copulae. Longer valves linear with broadly rounded apices (Fig. 19), becoming narrowly lanceolate to elliptic-lanceolate in smaller valves with more cuneately rounded (Figs 21, 22), sometimes almost subrostrate apices (Fig. 23). Valve margins weakly convex (Fig. 21) to almost straight in the middle (Figs 20, 22, 24), lacking any constriction. Valve dimensions (n = 16): length 22.0–49.5 µm, width 4.5–6.5 µm. [Valves (n = 27) observed in other populations on Livingston Island during the study (Figs 60–77, 79) had a valve length of 18–50 µm and a valve width of 4.0–6.5 µm]. Axial area very narrow, linear (Figs 19–24, 28). Central area narrow, forming an almost rectangular (Fig. 19) to bow-tie-shaped fascia (Figs 20–24, 28), widening towards the valve margins. Raphe filiform, straight (Fig. 19) to weakly undulating, with expanded central raphe endings, and elongated terminal raphe fissures, unilaterally weakly bent (Figs 21, 24, 28). Striae rather coarse, parallel to occasionally very weakly radiate in the middle (Fig. 22), parallel to very weakly convergent near the apices (Figs 19, 24), 22–24 in 10 µm. Areolae, at least the larger ones bordering the axial area, weakly discernible in LM (Fig. 19). SEM observations (Figs 8–56):— Valve face weakly domed, with a deep mantle (Figs 48–51). External raphe branches straight with weakly undulating (Fig. 49) to straight (Fig. 51) central raphe endings, terminating in drop-like expanded pores (Figs 49, 51). Terminal raphe fissures continuing shortly onto the mantle, unilaterally hooked (Figs 48, 51). Axial area triangularly expanded at the apices, bearing a silica flap on one side, covering the terminal raphe fissures (Fig. 50). Striae uniseriate, composed of cribrate, rounded to elliptic areolae. Near the raphe areolae clearly larger (Figs 49, 50 and Figs 88–90). Cribrum structure of the areolae bordering the axial area possessing four to seven peripheral pores, and two to three central pores. All other areolae with cribra composed of 2–5 peripheral pores, lacking central pores (Figs 49, 50). Areolae continuing around the apices (Figs 48, 50), ca. 25–30 in 10 µm. Internal areolar openings rounded to elliptic (Figs 53–56). Internal raphe straight, located on a distinct sternum (Figs 52, 53). Central raphe endings terminating onto double helictoglossae (Figs 53, 55). Terminal raphe endings finish onto broad helictoglossae. Stauros narrow, located on a wider hyaline fascia (Figs 52, 53, 55). Type:— ANTARCTICA. South Shetland Islands: Livingston Island, Hannah Point, sample 14 (62° 39’13” S, 60° 36’ 41” W), marine epilithon, R. Zidarova, 16th December 2018 (holotype BR-4760! = Fig. 28, isotype Slide 417! (University of Antwerp, Belgium)). Etymology:— The species epithet, confusus, Latin for confusing, reflects the complex taxonomic history of the genus Craspedostauros in the Antarctic Region, and the possible long-term inclusion of this species within the more common Antarctic species C. laevissimus. Ecology and associated diatom flora:— Craspedostauros confusus sp. nov. was found as abundant in the epilithon of several tidal pools at Hannah Point (sample 14, type), Mongolian (Reserve) Port (samples DNA5 and MO’), and Caleta Argentina (sample LT6). The salinity level in the pools (when measured) ranged between 33 and 35 PSU (Table 1), and their diatom flora was dominated by various species, including Navicula spp., Melosira spp., Parlibellus sp., Tabulariopsis australis (Peragallo 1921: 67) D.M. Williams (1988: 249) and Tripterion margaritae (Frenguelli & Orlando 1958: 98) L.F. Fernandes & Sar (2009: 67).

Fragilaria crocodylus Van de Vijver & C.E.Wetzel sp. nov. (Figs 1–19 LM, 20–25 SEM) Frustules rectangular in girdle view (Fig. 1), solitary although valves connected to each using small conical spines also observed (Fig. 21). Valves linear to weakly linear-lanceolate with almost parallel margins. Valves occasionally bent. Apices clearly protracted, typically capitate in longer valves (Figs 2–19). Smaller valves with more rostrate apices (Figs 18–19). Continuous series of small, solid, conical spines, each located in a pit-like depression, present on the valve margin (Figs 20, 23–24). At the apices, short series of spines present above the apical pore field (Fig. 22). Large mantle plaques present on the mantle edge (Figs 22, 25). Valve dimensions (n=25): length 40–110 µm, width 2.5–3.0 µm. Sternum narrow but distinct, linear, very gradually widening towards the central area. Central area small, asymmetrical with a rectangular unilateral fascia on one side and slightly shortened striae on the opposite side (Fig. 24). Striae uniseriate, composed of relatively large, rimmed rounded areolae externally covered by individual vola (Fig. 22). Near the sternum, striae terminating in short shallow slits (Fig. 24). Mantle striae composed of 3–4 rounded areolae (Figs 20–21). Apical pore field large, well, delimited, of ocellolimbus type, composed of up to 7 rows of small, squarish pores (Figs 22, 23). One rimoportula present, located in a fairly deep depression, transapically elongated (Figs. 22, 23). Internally, rimoportula large, raised (Fig. 25). Due to the rarity of the species in the sample, the dominance of other needle-shaped Fragilaria species in the sample and the age of the sample (late 19 th century), we did not find any valves with girdle bands. Observations on the girdle bands were therefore not possible. Type:— AUSTRIA. Attersee, Upper-Austria, Grunow sample 2646 (acc. number W0127051), coll. date VII.1862, leg. Von Mörl (n°48) (holotype slide BR-4736= Fig. 6, isotype slide 2646a in W, W0164874). PhycoBank registration: http:// phycobank.org/103275 Etymology:— The specific epithet “ crocodylus ” refers to the continuous series of conical marginal spines and the 5 spines at the apices, resembling the teeth of a crocodile (crocodylus). Ecology & associated diatom flora:— Sample 2646 was collected from stones in the Attersee, the largest lake in the province of Upper-Austria (Austria). The lake, situated at 470 m a.s.l., has a total surface of 45.9 km 2 with a maximum depth of 170 m (Dokulil & Teubner 2002). The sample is dominated by several Achnanthidium spp., Brachysira neoexilis LangeBertalot (in Lange-Bertalot & Moser 1994: 51), Denticula tenuis Kützing (1844: 43), Eucocconeis flexella (Kützing 1844: 80) F. Meister (1912: 95), Fragilaria perdelicatissima Lange-Bertalot & Van de Vijver (in Lange-Bertalot & Ulrich 2014: 19) and Humidophila perpusilla (Grunow 1860: 552) R.L. Lowe et al. (2014: 358). Following the ecological preferences of the observed species, based on literature data in Lange-Bertalot et al. (2017), this diatom flora points to oligotrophic, calcium bicarbonate enriched, low saprobity lake conditions. The Attersee has always been ultra-oligotrophic and therefore been considered a reference ecosystem for alpine lakes in the Austrian Salzkammergut district following the rules of the European Water Framework Directive (WFD) (Dokulil & Teubner 2002). Unfortunately, recent diatom data are lacking that could be used to compare the present-day diatom flora with the historic (19 th century) flora. The (European) distribution of the new species is unclear, most likely due to confusion with similar, needle-shaped Fragilaria species. Taxonomic comments:— Fragilaria crocodylus can hardly be confused with any other needle-shaped Fragilaria species. Fragilaria tenera lacks the distinctly developed, capitate apices but instead had narrow, weakly capitate apices (Lange-Bertalot & Ulrich 2014, Almeida et al. 2016). Moreover F. tenera has narrower valves (1.8–2.5 µm versus 2.5–3.0 µm) and therefore also a more needle-shaped valve outline with gradually tapering margins, contrary to the almost linear valve outline with parallel margins in F. crocodylus. The spines in F. tenera are shark-tooth like and are directly connected to the valve margin, whereas in F. crocodylus, the spines are conical and located in pit-like depressions (Almeida et al. 2016). Other longer Fragilaria species such as F. neotropica P.D.Almeida, E.Morales & C.E.Wetzel (in Almeida et al. 2016: 171) and F. salvadoriana K.J.Krahn & C.E.Wetzel (in Krahn et al. 2021: 5) sufficiently differ by their thin, linear-lanceolate valve outline, their lower valve width (, Published as part of Vijver, Bart Van De & Wetzel, Carlos E., 2022, A new Fragilaria Lyngbye species (Fragilariaceae, Bacillariophyta) from a historic Grunow sample from the Attersee, Austria, pp. 210-214 in Phytotaxa 561 (2) on pages 210-213, DOI: 10.11646/phytotaxa.561.2.9, http://zenodo.org/record/7059546, {"references":["Dokulil, M. T. & K. Teubner. (2002) Assessment of ecological integrity from environmental variables in an impacted oligotrophic alpine lake: Whole lake approach using 3 D-spatial heterogeneity. Water Air Soil Pollution, Focus 2: 165 - 80. https: // doi. org / 10.1023 / A: 1020320428487","Lange-Bertalot, H. & Moser, G. (1994) Brachysira. Monographie der Gattung und Naviculadicta nov. gen. Bibliotheca Diatomologica 29: 1 - 212.","Kutzing, F. T. (1844) Die kieselschaligen Bacillarien oder Diatomeen. W. Kohne, Nordhausen, 144 pp., 30 pls. https: // dx. doi. org / 10.5962 / bhl. title. 64360","Meister, F. (1912) Die Kieselalgen der Schweiz. Beitrage zur Kryptogamenflora der Schweiz. Materiaux pour la flore cryptogamique suisse. Vol. IV, fasc. 1. Bern: Druck und Verlag von K. J. Wyss, pp. [i] - vi, [1] - 254, 48 pls.","Lange-Bertalot, H. & Ulrich, S. (2014) Contributions to the taxonomy of needle-shaped Fragilaria and Ulnaria species. Lauterbornia 78: 1 - 73.","Grunow, A. (1860) Uber neue oder ungenugend gekannte Algen. Erste Folge, Diatomeen, Familie Naviculaceen. Verhandlungen der Kaiserlich-Koniglichen Zoologisch-Botanischen Gesellschaft in Wien 10: 503 - 582.","Lowe, R. L., Kociolek, P., Johansen, J. R., Van de Vijver, B., Lange-Bertalot, H. & Kopalova, K. (2014) Humidophila gen. nov., a new genus for a group of diatoms (Bacillariophyta) formerly within the genus Diadesmis: species from Hawai'i, including one new species. Diatom Research 29 (4): 351 - 360. https: // dx. doi. org / 10.1080 / 0269249 X. 2014.889039","Lange-Bertalot, H., Hofmann, G., Werum, M. & Cantonati, M. (2017) Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with updated taxonomy and added species. Koeltz Botanical Books, Schmitten- Oberreifenberg, 942 pp.","Almeida, P. D., Morales, E. A., Wetzel, C. E., Ector, L. & D. C. Bicudo (2016) Two new diatoms in the genus Fragilaria Lyngbye (Fragilariophyceae) from tropical reservoirs in Brazil and comparison with type material of F. tenera. Phytotaxa 246 (3): 163 - 183. https: // dx. doi. org / 10.11646 / phytotaxa. 246.3.1","Krahn, K. J., Schwartz, A., Wetzel, C. E., Cohuo-Duran, S., Daut, S., Marcario-Gonzales, L., Perez, L., Wand, J. & Schwalb, A. (2021) Three new needle-shaped Fragilaria species from Central America and the Tibetan Plateau. Phytotaxa 479 (1): 1 - 22. https: // doi. org / 10.11646 / phytotaxa. 479.1.1"]}

Eunotia sphagnicola Van de Vijver, A.Mertens & Lange-Bertalot, sp. nov. (Figs 37–84) Type:— THE NETHERLANDS, Egelmeer, Veenendaal, sample D283, coll. date 05.IV.1978, leg. H. van Dam, holo-BR-4716! (Meise Botanic Garden, Belgium), iso- slide 404! (University of Antwerp, Belgium). The holotype is represented by Fig. 44. PhycoBank registration:—http://phycobank.org/103146 Synonym:— Eunotia paludosa Grunow sensu Alles et al. 1991, Eunotia paludosa Grunow sensu Krammer & Lange-Bertalot 1991. To exclude from synonymy:— Eunotia paludosa Grunow 1862 LM (Figs 37–81): Frustules in girdle view roughly rectangular, frustule width 4–7 µm with slightly concave margins (Figs 37–39). Valves weakly arched with consistently more or less convex dorsal margins and variable ventral margins, ranging from almost straight in the shortest valves to moderately concave in medium-sized to longer specimens. Apices narrowly protracted, dorsally slightly or very slightly reflexed, sometimes simply broadly rounded. Valve dimensions (n=50): length 9.5–35.0 µm, width 2.0–2.5 µm, length-to-width ratio 5–13. Terminal raphe nodules close to the poles. Terminal raphe fissures comparatively rather short in the valve face, not attaining the middle, never closer to the dorsal side of valve poles but often difficult to discern in LM. Striae equidistant on the valve face, 21–23 in 10 µm. Areolae not discernible in LM. SEM (Figs 82–84): Striae uniseriate throughout, composed of small, rounded areolae, 48–50 in 10 µm (Figs 82, 83). Mantle striae ventrally composed of up to 5 areolae near the valve middle, only 2 near the apices (Fig. 82). Spines lacking (Fig. 83). Externally, raphe branches curving from valve mantle rather shortly up onto the valve face surrounded by a comparatively small terminal area, distinctly distant from the dorsal sides of the valve poles (Figs 82, 83). Single rimoportula present at one of both poles (Fig. 84, arrow), located close to the helictoglossa. Helictoglossa prominent at both poles (Fig. 84). Girdle composed of several open, perforated bands (Fig. 82). Etymology:—The specific epithet ‘ sphagnicola ’ refers to the almost exclusive preference of the new species for Sphagnum -dominated habitats. Distribution and ecology:—Due to severe damaging – or land use amelioration in an anthropogenic sense (pollution, draining, eutrophication) – ombrotrophic Sphagnum -bogs in Europe have been transformed into minerotrophic waters. As a consequence, Eunotia sphagnicola has become rare, although still abundant in places under disguise of the false name E. paludosa Grunow as shown here. In the past, E. sphagnicola was likewise mistaken for several other small-celled Eunotia taxa or viewed as a related infraspecific taxon. Its autecology (as E. paludosa) was investigated in detail by Alles et al. (1991) and Krammer & Lange-Bertalot (1991). During a study of the diatom associations in the Italian part of the southwestern Alps, Cantonati et al. (2011) investigated the “false E. paludosa ” in mountain mires, shallow pools with acidic, low mineralization waters, and peat bogs. In this study, E. sphagnicola (as E. paludosa) was almost exclusively found associated with Sphagnum spp. and a whole plethora of acidophilous and often acidobiontic diatoms, such as 18 different Eunotia species, among them E. paludosa Grunow (1862) s.s. in one locality, which was reported as E. fennica then. They also compared peat bogs and similar habitat types hosting E. sphagnicola (as E. paludosa) in the literature from the following countries: The Netherlands, Slovenia, border region of Czechia / Slovakia, Hungary, Romania, Volga Upland in Russia, North Mongolia. According to Lange-Bertalot et al. (2011, p. 186), E. sphagnicola (as E. paludosa) seems less abundant in “ minerotrophic peat bog complexes, dystrophic effluents, springs, brown water lakes or periodically wet habitats on sandstone rocks ”., Published as part of Vijver, Bart Van De, Lange-Bertalot, Horst, Goeyers, Charlotte, Mertens, Adrienne, Schuster, Tanja M. & Ector, Luc, 2022, The identity of Eunotia paludosa Grunow 1862 (Eunotiaceae, Bacillariophyta), a revision, and the description of three new species of Eunotia Ehrenberg, pp. 261-277 in Phytotaxa 545 (3) on pages 264-266, DOI: 10.11646/phytotaxa.545.3.2, http://zenodo.org/record/6541464, {"references":["Alles, E., Norpel-Schempp, M. & Lange-Bertalot, H. (1991) Zur Systematik und Okologie charakteristischer Eunotia - Arten (Bacillariophyceae) in elektrolytarmen Bachoberlaufen. Nova Hedwigia 53 (1 - 2): 171 - 213.","Krammer, K. & Lange-Bertalot, H. (1991) Bacillariophyceae 4. Teil: Achnanthaceae. Kritische Erganzungen zu Navicula (Lineolatae) und Gomphonema. Gesamtliteraturverzeichnis Teil 1 - 4. In: Ettl, H., Gartner, G., Gerloff, J., Heynig, H. & Mollenhauer, D. (eds.) Susswasserflora von Mitteleuropa. Gustav Fischer Verlag, Stuttgart, Jena, 437 pp.","Grunow, A. (1862) Die osterreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitaten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Meridioneae, Diatomeae, Entopyleae, Surirelleae, Amphipleureae. Verhandlungen der kaiserlich-koniglichen zoologisch-botanischen Gesellschaft in Wien 12: 315 - 472 [Abt 1]. https: // doi. org / 10.5962 / bhl. title. 64361","Lange-Bertalot, H., Bak, M. & Witkowski, A. (2011) Eunotia and some related genera. Diatoms of Europe 6: 1 - 747."]}

Eunotia zackenbergensis Goeyers, Van de Vijver & Lange-Bertalot, sp. nov. (Figs 127–168) Type:— GREENLAND, Zackenberg (sample M446, coll. date VIII.1998, leg. L. Beyens), holo- BR-4718! (Meise Botanic Garden, Belgium), iso- slide 406! (University of Antwerp, Belgium). The holotype is represented by Fig. 133. PhycoBank registration:—http://phycobank.org/103148 LM (Figs 127–161): Frustules rectangular in girdle view (Fig. 127). Valves weakly arched with parallel margins. Dorsal margins clearly convex. Ventral margins moderately concave in almost all cell cycle stages, smaller valves becoming more or less straight. Apices protracted, obliquely subcapitate and usually dorsally reflexed in the entire cell diminution series. Valve dimensions (n=50): length 16–62 µm, width 2.5–3.0 µm, length-to-width ratio 6.8–20. Terminal raphe nodules close to the poles. Striae 21–22 in 10 µm, equidistant throughout the entire valve length. Areolae not discernible in LM. SEM (Figs 162–168): Striae uniseriate throughout, composed of small, rounded areolae, 42–44 in 10 µm (Figs 163, 164). Mantle striae ventrally composed of up to 7 small, rounded areolae near the valve middle (Fig. 162). Apices with two rows of small, circular areolae (Fig. 162). Spines lacking (Figs 162, 163). Externally, raphe branches curving from almost halfway on the valve mantle onto the valve face (Figs 162, 165). Terminal raphe fissures extending ca. halfway towards the dorsal side, visible on the valve face, ending in a distinct pore (Fig. 164). Single rimoportula present at one of both poles, internally located close to the helictoglossa (Figs 166, 167). Helictoglossa prominent at both poles (Figs 167, 168). Etymology:—The specific epithet zackenbergensis refers to Zackenberg, a Danish research station in the Northeast Greenland National Park in northeastern Greenland, where the species was first identified. Distribution and ecology:— Eunotia zackenbergensis was collected from very wet mosses, growing in an Arctic bog pond in northeastern Greenland. Van Kerckvoorde et al. (2000) identified the species as E. fallax A.Cleve (Cleve,1895: 33) and grouped the sample (M446) in an assemblage characterised by high frequencies of Rossithidium petersenii (Hustedt) Round & Bukhtiyarova (Hustedt 1937: 179, Round & Bukhtiyarova 1996: 178) and several Pinnularia species. The new species is one of the most frequently observed Eunotia species in Greenland, often reaching relative abundances of up to 70% of the total diatom composition and usually present in bog ponds or fens (Goeyers, unpubl. res.). Due to confusion with E. paludosa, regularly reported from Arctic localities, its precise ecology and distribution is at present not well known., Published as part of Vijver, Bart Van De, Lange-Bertalot, Horst, Goeyers, Charlotte, Mertens, Adrienne, Schuster, Tanja M. & Ector, Luc, 2022, The identity of Eunotia paludosa Grunow 1862 (Eunotiaceae, Bacillariophyta), a revision, and the description of three new species of Eunotia Ehrenberg, pp. 261-277 in Phytotaxa 545 (3) on pages 270-272, DOI: 10.11646/phytotaxa.545.3.2, http://zenodo.org/record/6541464, {"references":["Van Kerckvoorde, A., Trappeniers, K., Nijs, I. & Beyens, L. (2000) The epiphytic diatom assemblages from terrestrial mosses in Zackenberg (Northeast Greenland). Systematics and Geography of Plants 70 (2): 301 - 314. https: // doi. org / 10.2307 / 3668649","Cleve, A. (1895) On recent freshwater diatoms from Lule Lappmark in Sweden. Bihang till Kongliga Svenska Vetenskaps-Akademiens Handlingar 21 (Afd. III, 2): 1 - 44.","Hustedt, F. (1937) Susswasserdiatomeen von Island, Spitzbergen und den Faroer-Inseln. Botanisches Archiv 38: 152 - 207.","Round, F. E. & Bukhtiyarova, L. (1996) Four new genera based on Achnanthes (Achnanthidium) together with a re-definition of Achnanthidium. Diatom Research 11 (2): 345 - 361. http: // dx. doi. org / 10.1080 / 0269249 x. 1996.9705389"]}

Eunotia insularum Van de Vijver & Lange-Bertalot, sp. nov. (Figs 85–126) Type:— INDIAN OCEAN, La Grande Coulée, Ile de la Possession, Crozet Archipelago (sample BM290, coll. date 4.I.1998, leg. B. Van de Vijver), holo- BR-4717! (Meise Botanic Garden, Belgium), iso- slide 405! (University of Antwerp, Belgium). The holotype is represented by Fig. 94. PhycoBank registration:—http://phycobank.org/103147 Synonym:— Eunotia paludosa sensu Van de Vijver et al. (2014) To exclude from synonymy:— Eunotia paludosa Grunow 1862 LM (Figs 85–119): Frustules rectangular in girdle view with barely to very slightly concave ventral margins, frustule width 3.5–6.0 µm (Figs 85–87). Valves weakly arched with more or less convex dorsal margins. Ventral margins moderately concave in all cell cycle stages down to the shortest valves. Apices distinctly narrowed, strongly protracted, subcapitate and dorsally reflexed in all stages. Valve dimensions (n=50): length 17–44 µm [up to 70 µm in other populations on the sub-Antarctic islands (Van de Vijver et al. 2014)], width 2.0–2.5 µm (occasionally up to 3.5 µm), length-to-width ratio 17–20. Terminal raphe nodules close to the poles. Striae 18–20 in proximal parts, up to 22 in 10 µm in the distal parts. Areolae not discernible in LM. SEM (Figs 120–126): Striae uniseriate throughout, composed of small, rounded areolae, ca. 50 in 10 µm (Figs 120–122). Mantle striae ventrally composed of up to 6 small, rounded areolae near the valve middle, only 2 near the apices (Fig. 120). Spines lacking (Figs 121, 122). Externally, raphe branches curving from valve mantle onto the valve face (Figs 120, 122). Terminal raphe fissures extending rather long onto the valve face in a distinct pore, more than halfway to the dorsal margin (Figs 122, 124). Single rimoportula present at one of both poles, external opening distinctly visible between the smaller areolae (Fig. 123, arrow). Internally, rimoportula located close to the helictoglossa (Figs 125, 126). Helictoglossa prominent at both poles (Fig. 125). Girdle composed of 2–5 open, perforated copulae, including the valvocopula (Fig. 121). Etymology:—The specific epithet insularum is a plural genitive in Latin indicating here the sub-Antarctic islands where this species is found. Distribution and ecology:—Surprisingly, the new taxon appears to be a distinct, yet up until recently unidentfied Eunotia species. After revision of its taxonomic identity on all sub-Antarctic islands in the southern Atlantic and Indian Ocean, it becomes clear that E. insularum occurs over almost the entire sub-Antarctic region, encompassing the Atlantic and Indian Oceans. Currently, the new species was observed on seven archipelagos and islands, such as the Falklands/ Islas Malvinas (reported as E. pseudopaludosa in Jüttner & Van de Vijver 2018), South Georgia, Iles Crozet, Iles Kerguelen, and Heard Island (on the latter 4 localities reported as E. paludosa; Van de Vijver & Beyens 1998, Van de Vijver et al. 2001, 2002, 2004, Van de Vijver et al. 2014). However, the species seems absent, so far, from all neighbouring continents and the entire Holarctic realm. Eunotia insularum was frequently and abundantly observed (as E. paludosa) from wet acid soils and submerged to wet terrestrial mosses and bog ponds, mostly in peat-dominated valleys. A particular feature of all sub-Antarctic localities is the complete absence of Sphagnum species, replaced by mosses such as Drepanocladus uncinatus (Hedw.) Warnst. in the peat formation on these islands. On Ile Amsterdam, the most northern of the sub-Antarctic islands in the southern Indian Ocean, E. insularum was found associated with Sphagnum -dominated bog ponds, as this is the only island with this kind of vegetation (Van de Vijver et al. 2008, Flatberg et al. 2011, Chattová et al. 2021)., Published as part of Vijver, Bart Van De, Lange-Bertalot, Horst, Goeyers, Charlotte, Mertens, Adrienne, Schuster, Tanja M. & Ector, Luc, 2022, The identity of Eunotia paludosa Grunow 1862 (Eunotiaceae, Bacillariophyta), a revision, and the description of three new species of Eunotia Ehrenberg, pp. 261-277 in Phytotaxa 545 (3) on pages 267-268, DOI: 10.11646/phytotaxa.545.3.2, http://zenodo.org/record/6541464, {"references":["Van de Vijver, B., de Haan, M. & Lange-Bertalot, H. (2014) Revision of the genus Eunotia (Bacillariophyta) in the Antarctic Region. Plant Ecology and Evolution 147 (2): 256 - 284. https: // doi. org / 10.5091 / plecevo. 2014.930","Grunow, A. (1862) Die osterreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitaten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Meridioneae, Diatomeae, Entopyleae, Surirelleae, Amphipleureae. Verhandlungen der kaiserlich-koniglichen zoologisch-botanischen Gesellschaft in Wien 12: 315 - 472 [Abt 1]. https: // doi. org / 10.5962 / bhl. title. 64361","Juttner, I. & Van de Vijver, B. (2018) A preliminary account of diatom taxa in the Falkland Islands. Report to the Shackleton Scholarship Fund. 58 pp.","Van de Vijver, B. & Beyens, L. (1998) A preliminary study on the soil diatom assemblages from Ile de la Possession (Crozet, Subantarctica). European Journal of Soil Biology 34 (3): 133 - 141. https: // doi. org / 10.1016 / S 1164 - 5563 (00) 88650 - 1","Van de Vijver, B., Ledeganck, P. & Beyens, L. (2001) Habitat preferences in freshwater diatom communities from sub-Antarctic Iles Kerguelen. Antarctic Science 13 (1): 28 - 36. http: // dx. doi. org / 10.1017 / S 0954102001000050","Van de Vijver, B., Frenot, Y. & Beyens, L. (2002) Freshwater diatoms from Ile de la Possession (Crozet Archipelago, Subantarctica). Bibliotheca Diatomologica 46: 1 - 412.","Van de Vijver, B., Beyens, L., Vincke, S. & Gremmen, N. J. M. (2004) Moss-inhabiting diatom communities from Heard Island, sub- Antarctic. Polar Biology 27: 532 - 543. https: // doi. org / 10.1007 / s 00300 - 004 - 0629 - x","Van de Vijver, B., Beyens, L. & Lebouvier, M. (2008) The genus Eunotia on the volcanic island, Ile Amsterdam (Southern Indian Ocean). Nova Hedwigia 87 (1 - 2): 113 - 128. https: // doi. org / 10.1127 / 0029 - 5035 / 2008 / 0087 - 0113","Flatberg, K., Whinam, J. & Lebouvier, M. (2011) Three species of Sphagnum endemic to Ile Amsterdam, Terres Australes et Antarctiques Francaises: S. cavernulosum sp. nov., S. complanatum sp. nov. and S. islei. Journal of Bryology 33 (2): 105 - 121. https: // doi. org / 10.1179 / 1743282010 Y. 0000000019","Chattova, B., Lebouvier, M., Syrovatka, V. & Van de Vijver, B. (2021) Moss-inhabiting diatom communities from Ile Amsterdam (TAAF, southern Indian Ocean). Plant Ecology & Evolution 154 (1): 63 - 79. https: // doi. org / 10.5091 / plecevo. 2021.1767"]}

Eunotia paludosa Grunow 1862, p. 336, pl. 3, fig. 10, (Figs 1–36) Type:— AUSTRIA, Mandling (“in paludibus prope Mandling in Styria auctumno 1859”), Grunow sample 522, lectotype (Plate 3, figs 10c & d in Grunow 1862 designated in Lange-Bertalot et al. 2011, p. 232); isolectotypes (here designated): slide BR-4715! (BR, Meise Botanic Garden) and slide W0164808 both prepared based on Grunow sample 522 (Mandling, Styria, Austria, coll. date 30.IX.1859 (Grunow erroneously put 31/IX/ 1859 in his annotation book), leg. A. Grunow) PhycoBank registration:—http://phycobank.org/103145 Synonyms:— Eunotia denticulata var. fennica Hustedt (1932: 291), Eunotia fennica (Hustedt 1932: 291) Lange-Bertalot (in Werum & Lange-Bertalot 2004: 152), Published as part of Vijver, Bart Van De, Lange-Bertalot, Horst, Goeyers, Charlotte, Mertens, Adrienne, Schuster, Tanja M. & Ector, Luc, 2022, The identity of Eunotia paludosa Grunow 1862 (Eunotiaceae, Bacillariophyta), a revision, and the description of three new species of Eunotia Ehrenberg, pp. 261-277 in Phytotaxa 545 (3) on page 263, DOI: 10.11646/phytotaxa.545.3.2, http://zenodo.org/record/6541464, {"references":["Grunow, A. (1862) Die osterreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitaten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Meridioneae, Diatomeae, Entopyleae, Surirelleae, Amphipleureae. Verhandlungen der kaiserlich-koniglichen zoologisch-botanischen Gesellschaft in Wien 12: 315 - 472 [Abt 1]. https: // doi. org / 10.5962 / bhl. title. 64361","Lange-Bertalot, H., Bak, M. & Witkowski, A. (2011) Eunotia and some related genera. Diatoms of Europe 6: 1 - 747.","Hustedt, F. (1932) Die Kieselalgen Deutschlands, Osterreichs und der Schweiz unter Berucksichtigung der ubrigen Lander Europas sowie der angrenzenden Meeresgebiete. Vol. VII. Teil 2. Lieferung 2. In: Anon. (Eds.) Rabenhorst's Kryptogamen Flora von Deutschland, Osterreich und der Schweiz. Leipzig: Akademische Verlagsgesellschaft Geest & Portig K. - G. pp. 177 - 320.","Werum, M. & Lange-Bertalot, H. (2004) Diatoms in springs from Central Europe and elsewhere under the influence of hydrogeology and anthropogenic impacts. Iconographia Diatomologica 13: 3 - 417."]}

Staurosirella minutissima Van de Vijver sp. nov. (LM Figs 31–51, SEM 74–79) Description:— LM (Figs 31–51): Frustules in girdle view rectangular, in pairs (Fig. 31) or solitary (Fig. 32). Long colonies not observed. Valves isopolar to occasionally very slightly heteropolar (e.g. Figs 35, 36), elliptic to ellipticlanceolate. Apices broadly rounded, not protracted. Valve dimensions (n=30): valve length 5–12 µm, width 3.0–3.5 µm. Sternum very narrow, linear to occasionally very weakly lanceolate. Striae alternating at both sides of the sternum, weakly radiate near the valve middle, becoming distinctly more radiate towards the apices, 15–16 in 10 µm. Areolae not discernible in LM. Valvocopula with fimbriae (Fig. 51). SEM (Figs 74–79): Valve face surface weakly undulating with slightly raised virgae and striae slightly sunken in ‘punch hole-like’ depressions (Figs 74, 76). Virgae broader that the striae. Striae extending without interruption from the valve face onto the mantle narrowing on the valve mantle (Fig. 76). Large hyaline zone present at the abvalvar mantle edge (Figs 75, 76). Striae uniseriate, composed of short, slit-like, linear areolae, running parallel to the apical axis (Figs 74–78). Vimines narrow, not raised. Marginal spines located on the virgae, always in pairs flanking the striae. Spines rounded, thin at the base (Fig. 76), becoming broader, more spatulate at the top (Fig. 78). Mantle plaques absent (Fig. 76). Apical pore fields present at both apices, usually similar in size and shape (Figs 74, 75–70), located at the valve face/mantle junction, extending more onto the valve mantle, isolated from neighboring striae. Pore fields composed of three rows of small, rimmed pores. Girdle composed of an open valvocopula and several open, plain copulae (Fig. 75). Internally, striae distinctly sunken between the raised virgae and the sternum (Figs 77, 79). Areolae internally occluded by irregularly shaped volae, extending from the sides of the areolae projected towards the valve interior (Figs 77, 79). Type:— SWITZERLAND, Casaccio, south side of the Lukmanier (border between the cantons of Graubünden and Ticino), prepared from Rabenhorst exsiccata sample 1441 (exsiccata set Algen Sachen’s & Europa’s) (holotype BR-4712!, isotype Slide 403 (University of Antwerp, Belgium)). The holotype is represented here by Fig. 11. Duplicates of the Rabenhorst material No. 1441 and Wartmann & Schenk as sample 233 can be found in numerous herbaria worldwide (e.g. Stafleu & Cowan 1983: 465; 1988: 93). Etymology:— The specific epithet ‘ minutissima ’ refers to the small valve dimensions. Associated diatom flora in Rabenhorst 1441:— The sample is populated by a highly diverse diatom flora. Dominant species (>5 % of the total diatom count) include Achnanthidium polonicum Van de Vijver et al. (in Wojtal et al. 2011: 223), Cymbella excisiformis Krammer (2002: 31), Denticula tenuis Kützing (1844: 43), Delicatophycus delicatulus (Kützing 1849: 59) M.J. Wynne (2019: 1), Pseudostaurosira robusta (Fusey) D.M. Williams & Round (1987: 278), Staurosirella coutelasiana, S. minutissima and S. neopinnata. Less frequent taxa include Brachysira neoexilis Lange-Bertalot in Lange-Bertalot & Moser (1994: 51), Caloneis latiuscula (Kützing 1844: 93) Cleve (1894: 61), Cymbella helvetica Kützing (1844: 79), Nitzschia bryophila (Hustedt 1937: 204) Hustedt (1943: 232), Pseudostaurosira parasitica (W. Smith 1856: 19) E.Morales (in Morales & Edlund 2003: 287) and Staurosira inflata (Heiden 1900: 14) A.Rusanov et al. (in Rusanov et al. 2018: 341). This diatom flora represents an unpolluted, alpine environment. Most species are typically found in circumneutral to alkaline (calcium-carbonate rich), oligotrophic, oligosaprobic lakes and rivers with low to moderate electrolyte contents (Lange-Bertalot et al. 2017). As both Staurosirella coutelasiana and S. minutissima are rather abundantly present in the sample, it is highly likely that both are typically found in these conditions., Published as part of Vijver, Bart Van De, 2022, Two new Staurosirella species (Staurosiraceae, Bacillariophyta) observed in an historic Rabenhorst sample, pp. 163-174 in Phytotaxa 545 (2) on pages 166-170, DOI: 10.11646/phytotaxa.545.2.5, http://zenodo.org/record/6534689, {"references":["Stafleu, F. A. & Cowan, R. S. (1983) Taxonomic literature, volume IV: P - Sak (2 nd ed.). Utrecht, Antwerpen: Bohn, Scheltema & Holkema; The Hague, Boston: dr. W. Junk Publishers. 1214 pp.","Stafleu, F. A. & Cowan, R. S. (1988) Taxonomic literature, volume VII: W - Z (2 nd ed.). Utrecht, Antwerpen: Bohn, Scheltema & Holkema; The Hague, Boston: dr. W. Junk Publishers. 653 pp.","Wojtal, A. Z., Ector, L., Van de Vijver, B., Morales, E. A., Blanco, S., Piatek, J. & Smieja, A. (2011) The Achnanthidium minutissimum complex (Bacillariophyceae) in southern Poland. Algological Studies 136 (1): 211 - 238. https: // doi. org / 10.1127 / 1864 - 1318 / 2011 / 0136 - 0211","Krammer, K. (2002) Cymbella. In: Diatoms of Europe 3. 584 pp.","Kutzing, F. T. (1844) Die Kieselschaligen Bacillarien oder Diatomeen. Nordhausen: zu finden bei W. Kohne. pp. [i - vii], [1] - 152.","Kutzing, F. T. (1849) Species algarum. Lipsiae [Leipzig]: F. A. Brockhaus. pp. [i] - vi, [1] - 922.","Wynne, M. J. (2019) Delicatophycus gen. nov.: a validation of \" Delicata Krammer \" inval. (Gomphonemataceae, Bacillariophyta). Notulae Algarum 97: 1 - 3.","Williams, D. M. & Round, F. E. (1987) Revision of the genus Fragilaria. Diatom Research 2: 267 - 288. https: // doi. org / 10.1080 / 0269249 X. 1987.9705004","Lange-Bertalot, H. & Moser, G. (1994) Brachysira. Monographie der Gattung und Naviculadicta nov. gen. Biblioteca Diatomologica 29: 1 - 212.","Cleve, P. T. (1894) Synopsis of the naviculoid diatoms. Part I. Kongliga Svenska Vetenskapsakademiens Handlingar Series 4 26 (2): 1 - 194.","Hustedt, F. (1937) Susswasserdiatomeen von Island, Spitzbergen und den Faroer-Inseln. Botanisches Archiv 38: 152 - 207.","Hustedt, F. (1943) Die Diatomeenflora einiger Hochgebirgsseen der Landschaft Davos in den schweizer Alpen. Internationale Revue der gesamten Hydrobiologie und Hydrographie 43: 124 - 197, 225 - 280.","Smith, W. (1856) A synopsis of the British Diatomaceae; with remarks on their structure, functions and distribution; and instructions for collecting and preserving specimens. Vol. 2. pp. [i - vi] - xxix, 1 - 107.","Morales, E. A. & Edlund, M. B. (2003) Studies in selected fragilarioid diatoms (Bacillariophyceae) from Lake Hovsgol, Mongolia. Phycological Research 51 (4): 225 - 239. https: // doi. org / 10.1111 / j. 1440 - 1835.2003 .. x","Heiden, H. (1900) Diatomeen des Coventer Sees bei Doberan von der Litorina bis zur Jetztzeit. Mitteilungen aus der Grossherzoglich Mecklenburg Geologisches Landesanstalt 10 (21): 1 - 32.","Rusanov, A. G., Ector, L., Morales, E. A., Kiss, K. T. & Acs, E. (2018) Morphometric analyses of Staurosira inflata comb. nov. (Bacillariophyceae) and the morphologically related Staurosira tabellaria from north-western Russia. European Journal of Phycology 53 (3): 336 - 349. https: // doi. org / 10.1080 / 09670262.2018.1452050"]}

Staurosirella coutelasiana Van de Vijver sp. nov. (LM Figs 1–30, SEM Figs 69–73) Description:— LM (Figs 1–29 (30?)): Frustules in girdle view rectangular, solitary (Fig. 1). Colonies not observed. Valves isopolar to occasionally very slightly heteropolar (e.g. Figs 16, 28), linear-lanceolate in larger specimens to lanceolate, occasionally elliptic-lanceolate in smaller valves. Valve outline in larger specimens often more irregular in shape (Figs 4, 5 & 8). Apices broadly rounded, not protracted. Valve dimensions (n=50): valve length 15–35 µm, width 5.0–5.5 µm. Sternum narrow, linear to slightly lanceolate. Striae alternating at both sides of the sternum, parallel to weakly radiate near the valve middle, becoming distinctly more radiate towards the apices, 9–11 in 10 µm. Areolae not discernible in LM. SEM (Figs 69–73): External valve face undulating with raised virgae and striae slightly sunken in ‘punch holelike’ depressions (Figs 69, 70). Striae extending without interruption from the valve face onto the mantle gradually narrowing at both ends (Fig. 71) giving the striae a lanceolate appearance. Large hyaline zone present at the abvalvar mantle edge (Fig. 73). Striae uniseriate, composed of long, slit-like, linear areolae, running parallel to the apical axis (Figs 69–71). Vimines not raised. Marginal spines located on the virgae, irregularly shaped (acute to spatulate), originating from one (Fig. 70) or two points (Figs 69, 71). Spine base hollow (Fig. 71). Apical pore fields present at both apices, usually similar in size and shape (Figs 69–70), located at the valve face/mantle junction, extending more onto the valve mantle, isolated from neighboring striae. Pore fields composed of small, rimmed pores, arranged in several irregular rows. Valvocopula with short but well developed fimbriae (Fig. 72). Internally, striae distinctly sunken between the flat, doubly flared virgae and sternum (Fig. 73). Areolae occluded by irregularly shaped volae, extending from the longer inner side of each vimen (Fig. 73). Type:— SWITZERLAND, Casaccio, south side of the Lukmanier (border between the cantons of Graubünden and Ticino), prepared from Rabenhorst exsiccata sample 1441 (exsiccata set Algen Sachen’s & Europa’s) (holotype BR-4711!, isotype Slide 402 (University of Antwerp, Belgium)). The holotype is represented here by Fig. 11. Duplicates of the Rabenhorst material No. 1441 and Wartmann & Schenk as sample 233 can be found in numerous herbaria worldwide (e.g. Stafleu & Cowan 1983: 465; 1988: 93). Etymology:— The new species is named after my dear friend, Mrs. Marine Coutelas (Chavignon, France), a young enthusiast French artist with a passion for the world of plants and diatoms. Comments:— Due to confusion with S. neopinnata, also present in the sample, it is difficult to establish what the smallest specimens of this new species could be. Figure 30 represents a short, elliptical valve (length 7 µm) that can represent either S. coutelasiana but also S. neopinnata (see Figs 53–68 for the S. neopinnata population observed in the sample). It is impossible to attribute this valve with 100 % certainty to any of both species. Therefore, the smallest valve that undoubtedly can be identified as S. coutelasiana is Fig. 29 with a valve length of 15 µm., Published as part of Vijver, Bart Van De, 2022, Two new Staurosirella species (Staurosiraceae, Bacillariophyta) observed in an historic Rabenhorst sample, pp. 163-174 in Phytotaxa 545 (2) on page 165, DOI: 10.11646/phytotaxa.545.2.5, http://zenodo.org/record/6534689, {"references":["Stafleu, F. A. & Cowan, R. S. (1983) Taxonomic literature, volume IV: P - Sak (2 nd ed.). Utrecht, Antwerpen: Bohn, Scheltema & Holkema; The Hague, Boston: dr. W. Junk Publishers. 1214 pp.","Stafleu, F. A. & Cowan, R. S. (1988) Taxonomic literature, volume VII: W - Z (2 nd ed.). Utrecht, Antwerpen: Bohn, Scheltema & Holkema; The Hague, Boston: dr. W. Junk Publishers. 653 pp."]}

Staurosirella tigris M.A.Harper, E.Morales & Van de Vijver, sp. nov. (Figs 1–20) Description:— LM (Figs 1–15): Frustules rectangular in girdle view (Fig. 1), occasionally linked valve face to valve face, form short filaments (not shown). Valves linear, dog-bone-shaped with ends having two lateral lobes, each terminating in broadly rounded apices. Longitudinal axis longer than transapical axis. Smaller valves almost quadri- to tri-radiate (Figs 14, 15). Valve dimensions between the lobes (n=30): central length 22–34 µm, central width 7.5–14.0 µm. Dimensions measuring from apices of lobes (n=30): length 24–43 µm, width 16.5 – 24.0 µm. Mantle depth (n=6): 6.0–7.5 µm. Axial sternum linear, moderately broad, approximately 1/4–1/3 of the total valve width (measured in the center), occasionally slightly eccentric due to unequal shortening of central striae (e.g. Figs 4, 8). Sternum continuing but gradually narrowing into the terminal lateral lobes. Striae present on all four margins, 6–7 in 10 µm, gradually shortening from the middle towards the apices, parallel in the center along the valve face longitudinal axis, more radiate towards the apices. Between apical lobes, striae typically radiate. Areolae not or only very weakly discernible in LM. SEM (Figs 16–20): Valve face slightly undulate with virgae slightly raised above the striae (Figs 16, 17 &18). Virgae not wider or as wide as the striae. Vimines apparently continuing as low raised ridges on the virgae (Fig. 17, arrows). Striae uniseriate, composed of lineolate areolae, ca. 42–45 in 10 µm (n=7). Striae continuing without interruption onto the mantle. Small, hollow conical spines present on the virgae between the striae (Fig. 17). Apical porefields of ocellulimbus type, large, composed of many parallel rows of small pores, present at each apex (Fig. 18). Internally, apical porefields obscured by thickening of the valve margin and virgae thickened with striae sunken in between them (Fig. 20). Rimoportulae not observed. Girdle composed of several bands (Fig. 19). Valvocopula clearly fimbriate (Fig. 19). Type:— ANTARCTICA, Mid-Miocene glacial-lacustrine sediments in the Friis Hills, sample WD 19 (Friis Hills Drilling Project site 1, drill hole 1B core 3 preliminary sample at 16.295 m drillers’ depth) (161°26’57.646” E / 77°45’2.681”S, alt 1259 m, coll. date 25th May 2017, leg. Warren Dickinson), (holotype BR-4689!= Fig. 6, isotype PLP-393, University of Antwerp). Etymology:— The specific epithet “ tigris ” meaning “tiger” in Latin, refers to the general outlook of the species resembling a tiger-skin rug. Age:— Early to Middle Miocene, younger than 19.76 Ma based on occurrence in Friis Drift II above a 19.76 Ma tephra bed. Older than ~14 Ma as fossils of Nothofagus Blume (Southern beech) and Isoetes L. (Cantrill et a l. 2016) indicate a moist warm climate before the mid-Miocene climate transition of ~13.9 Ma (Lewis & Ashworth 2016). More precise dating based on 40 Ar/ 39 Ar dating of the tephra deposits in the Friis Hills Drillholes constrains the age of these sediments to between 15–14 Ma (Verret et al. 2020, Chorley 2021). Distribution and Ecology:— The new species was found in several samples, together with large populations of another Staurosirella species (Pinseel et al. 2016a, see two largest Staurosirella valves). The observed diatom flora, co-dominated by these Staurosirella species together with (at present unidentified) Aulacoseira taxa most likely indicates the presence of shallow, open water as these tychoplanktonic taxa often thrive in waters prone to regular mixing. Staurosirella tigris was absent from more peaty samples co-dominated by Eunotia and Brachysira indicating it preferred more oligotrophic conditions than the latter two genera. The deposits contain macrofossils that indicate tundra vegetation (Lewis & Ashworth 2016)., Published as part of Harper, Margaret A., Morales, Eduardo A. & Vijver, Bart Van De, 2022, An unusual freshwater diatom with bilobate ends from the Mid-Miocene of East Antarctica: Staurosirella tigris sp. nov. (Fragilariaceae, Bacillariophyta), pp. 201-208 in Phytotaxa 541 (2) on pages 203-205, DOI: 10.11646/phytotaxa.541.2.10, http://zenodo.org/record/6388606, {"references":["Lewis, A. R. & Ashworth, A. C. (2016) An early to middle Miocene record of ice-sheet and landscape evolution from the Friis Hills, Antarctica. Geological Society of America Bulletin 128 (5 - 6): 719 - 738. https: // doi. org / 10.1130 / B 31319.1","Verret, M., Dickinson, W., Lacelle, D., Fisher, D., Norton, D., Chorley, H., Levy, R. & Naish, T. (2020) Cryostratigraphy of mid-Miocene permafrost at Friis Hills, McMurdo Dry Valleys of Antarctica. Antarctic Science 33 (2): 174 - 188. https: // doi. org / 10.1017 / S 0954102020000619","Chorley, H. K. (2021) Antarctic ice sheet and climate evolution during the mid-Miocene. PhD thesis Victoria University of Wellington.","Pinseel, E., Harper, M. A, Wolfe, A. P., Lewis, A. R., Dickinson, W., Ashworth, A. C., Sabbe, K., Van de Vijver, B., Verleyen, E. & Vyverman, W. (2016 a) The Miocene freshwater diatom flora of the Antarctic Continent. In: 24 th International diatom symposium: program and abstracts. University of Ghent, Academic Bibliography, pp. 122. [https: // biblio. ugent. be / publication / 8196961]"]}

Background Ice-free areas in the Antarctic region are strongly limited. The presence of marine mammals and birds in those areas influence soil properties and vegetation composition. Studies on the terrestrial diatom flora in soils influenced by sea birds in the Maritime Antarctic region are scarce. Methods Samples were collected from two transects on the western shore of the Admiralty Bay region. Light and scanning electron microscopic observations and statistical analyses were conducted to consider the impact of penguin rookeries on soil diatom assemblages. Results The disturbance associated with the presence of penguin rookeries clearly influences the soil diatom diversity. Assemblages from areas with the highest nutrient input were characterized by a much lower diversity with only few species dominating the flora. One of recorded taxa could not be assigned to any of the known species. Therefore, based on the combination of morphological features analyzed using light and scanning electron microscopes and comparison with similar taxa in the Antarctic region and worldwide, the species is described hereby as new to science–Luticola kaweckae sp.nov. The new species is characteristic for soil habitats with strong penguin influence.

A new species of araphid diatoms with bilobate ends is described as Staurosirella tigris sp. nov. It was found in mid-Miocene glacial-lacustrine sediments in the Friis Hills, Antarctica. The new diatom is placed in Staurosirella because it has striae composed of apically-oriented lineolae, separated by long, thin vimines, and it lacks rimoportulae. It can be easily distinguished by its rectangular valve shape with bilobate ends, differing from Staurosirella grunowii, another four-lobed Miocene species, by having a rectangular central portion to its valves instead of being cross-shaped with the four lobes arising from a common central area. Also, the distribution of the new species is different, to date only being found in Antarctica, while S. grunowii is restricted to the Northern Hemisphere.

Fragilaria irregularis Chudaev, J��ttner & Van de Vijver, sp. nov. (Figs 1���56) Description:���LM (Figs 1���48): Cells solitary, ribbon-like colonies not observed. Valves linear in larger and mediumsized specimens to linear-elliptic in smaller specimens. Valve margins tapering abruptly forming well developed ���shoulders��� near the apices. Apices distinctly protracted, subcapitate. Valve margins sometimes slightly irregular, often with different curvature on both sides of the valve, resulting in an asymmetrical valve shape with a margin slightly more arched on one side and a straight margin on the opposite side. Valve dimensions (n=50): length 14���27 ��m, width 3.5���5.5 ��m. Sternum distinct although very narrow, linear, not widening in the central part of the valve. Central area absent. Striae alternating, parallel throughout most of the valve, becoming radiate close to apices, irregularly spaced with some virgae much wider than striae, 7���14 in 10 ��m. Occasionally, striae slightly shortened (Figs 1, 4, 9, 13, 14, 42, 47). Valves showing a more regular striation pattern rare (Figs 12, 28, 34, 44). Areolae not discernible in LM. SEM (Figs 49���56): Valve surface almost flat. Spines or spine vestiges not observed (Figs 49���50, 54, 55). Large mantle plaques visible at mantle edge (Fig. 55, white arrow). Striae uniseriate, composed of small, circular, usually rimmed areolae; 49���63 areolae in 10 ��m (Figs 49���50, 54���56). One transapically elongated rimoportula present at one apex, replacing part of the last stria (Figs 49���52, white arrowheads, 55���56, black arrowheads). Apical pore fields composed of several rows of very small poroids (Figs 56, white arrow). Internally, virgae not or only weakly raised above the areolae, the latter present in very shallow grooves. Rimoportula straight to oblique, forming a transapically elongate, lipped slit (Figs 51���52, white arrowheads). Cingulum composed of at least two open copulae bearing one row of circular perforations (Fig. 53, white arrow) at the junction of pars interior and pars exterior. Most abvalvar copula ligulate (Fig. 56, white arrowhead), valvocopula lacking ligula (Figs 53���56). Type:��� RUSSIA. Krasnodar Territory: Adegoy River, vicinity of Afonka Khutor, on mosses, 44.72580�� N, 37.93992�� E, 176 m asl, D. A . Chudaev, 27th May 2016 (Holotype: MW-D! slide 501s1 = Fig. 7; isotypes: slides LE A0000300, LE A0000303). Etymology:���The specific epithet refers to the irregular striation pattern. Ecology and distribution:���The species is so far only known from its type locality, the Adegoy River, where it was present at a relative abundance of 6.5%. The associated diatom flora in the sample was composed of several, at present unidentified, species in Achnanthidium K��tzing (1844: 75, 40%) and Encyonopsis Krammer (1997: 156, 3%), Diatoma moniliformis (K��tzing 1834: 580) D.M. Williams (2012: 260, 11%), Gomphonella olivacea (Hornemann 1810: fasc. 24, pl. 1429) Rabenhorst (1853: 61, 3%), Gomphonema tergestinum (Grunow in Van Heurck 1880: pl. 25, fig. 40) Fricke in A. Schmidt (1902: pl. 234, figs 39���43, 5%), Navicula cryptotenella Lange-Bertalot in Krammer & Lange-Bertalot (1985: 62, 3%) and Nitzschia media Hantzsch (1860: 40, 6%)., Published as part of Chudaev, Dmitry, J��ttner, Ingrid & Vijver, Bart Van De, 2021, Fragilaria irregularis sp. nov. a new araphid species (Fragilariaceae, Bacillariophyta) from the River Adegoy, Krasnodar Territory, Russia, pp. 221-228 in Phytotaxa 508 (2) on pages 222-223, DOI: 10.11646/phytotaxa.508.2.11, http://zenodo.org/record/5425819, {"references":["Kutzing, F. T. (1844) Die Kieselschaligen Bacillarien oder Diatomeen. W. Kohne, Nordhausen, 152 pp.","Krammer, K. (1997) Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 1. Allgemeines und Encyonema Part. Bibliotheca Diatomologica 36: 1 - 382.","Kutzing, F. T. (1834). Synopsis diatomearum oder Versuch einer systematischen Zusammenstellung der Diatomeen. Linnaea 8: 529 - 620.","Williams, D. M. (2012) Diatoma moniliforme: commentary, relationships and an appropriate name. Nova Hedwigia, Beiheft 14: 255 - 261.","Hornemann, J. W. (1810) Icones plantarum sponte nascentium in Regnis Daniae Norvegiae, et in Ducatibus Slesvici et Holsatiae ad illustrandum opus de iisdem plantis, Regio jussu exarandum, Florae Danicae nomine inscriptum. Typis E. A. H. Molleri, Hauniae. Vol. 8 (fasc. 22, 23, 24). pls. 1261 - 1440.","Rabenhorst, L. (1853) Die Susswasser-Diatomaceen (Bacillarien.): fur Freunde der Mikroskopie. Eduard Kummer, Leipzig, 72 pp.","Van Heurck, H. (1880) Synopsis des Diatomees de Belgique Atlas. Ducaju et Cie, Anvers. pls I - XXX.","Schmidt, A. (1902) Atlas der Diatomaceen-kunde. O. R. Reisland, Leipzig. Series V: Heft 59 - 60. pls 233 - 240.","Krammer, K. & Lange-Bertalot, H. (1985) Naviculaceae Neue und wenig bekannte Taxa, neue Kombinationen und Synonyme sowie Bemerkungen zu einigen Gattungen. Bibliotheca Diatomologica 9: 1 - 230.","Hantzsch, C. A. (1860) Neue Bacillarien: Nitzschia vivax var. elongata, Cymatopleura nobilis. Hedwigia 2 (7): 1 - 40."]}

Arcanodiscus saundersianus Goeyers & Van de Vijver sp. nov. http://phycobank.org/ 102320 Figs 97–115, 132–138 Etymology The species is named in honour of our colleague Dr Krystyna Saunders (Australian Nuclear Science and Technology Organisation, Kirrawee, Australia) to acknowledge her for her ecological and paleoecological diatom research on the sub-Antarctic islands in the Pacific Ocean. Material examined Holotype CAMPBELL ISLAND • sub-Antarctic region; sample BAS272; 26 Dec. 1969; D. Vitt leg.; BR-4581. Isotype CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-372. Description Light microscopy (Figs 97–115) Frustules broadly discoid, almost square to rectangular with broadly rounded edges and convex valve faces. Frustules often found attached to each other. Chains composed of more than 2 cells however never observed. Multiple discoid chloroplasts present. Girdle bands not discernible in LM. Valves rather strongly silicified, rounded with a thick mantle and convex, weakly domed valve face. Valve dimensions (n = 25): valve diameter 6–17.5 μm, frustule height (n = 10): 4.5–7.0 μm. Central area is a large, smooth, hyaline zone, 3.0–7.5 μm, 50–55% of the total valve diameter, surrounded by a more rugose, irregularly shaped, marginal zone where striae are difficult to distinguish. Visible processes lacking. Scanning electron microscopy (Figs 132–138) Frustules discoid with very heavily silicified valves, visible as a thick mantle (Figs 132, 137). Cingulum comprises several, narrow, very thin, non-perforated, open copulae (Fig. 132). Pars interior of the copulae clearly fimbriate giving the impression of perforations on the copulae when girdle not eroded (Figs 132, 133, arrows). Copulae clearly open, ligulate (Fig. 132, double arrows). Valve face with large, flat hyaline, clearly rounded central area, lacking areolae and any other ornamentation (Figs 134–136). Marginal zone gently sloping towards the mantle, entirely covered with rounded to slit-like areolae, ca 45 in 10 μm, organized in irregular striae, the latter ca 40 in 10 μm. Areola occlusions externally not observed (Figs 134–135). External openings of portulae not distinguishable from areola openings. No silica thickenings, close to valve face/mantle junction (Fig. 135). Striae continuing over the valve face/mantle junction, usually interrupted by a series of up to 3 parallel ridges running entirely around the mantle (Figs 134–135). Parallel ridges, usually covered by girdle bands (Fig. 133), occasionally lacking and resulting in a broad, flat mantle (Fig. 136). Areolae on the mantle strictly rounded. Mantle edge indistinct. Internally, areolae rather large, each showing a clear rota, covered by very thin hymenes, organized in irregularly running striae (Fig. 138). Central area a large hyaline, irregularly bordered, central zone (Fig. 137). Large number of perforated, thickened protuberances visible, irregularly scattered between the areolae, never organized in a regular marginal ring (Fig. 137, arrows). Inner openings of these protuberances rounded, smaller than the areolae, lacking rota (Fig. 138). Ecology and distribution Arcanodiscus saundersianus sp. nov. was found in a sample collected from a dripping bluff limestone. The sample is entirely dominated by the new species of Arcanodiscus. Sub-dominant species include Achnanthes muelleri, Diatomella balfouriana and several species of Humidophila., Published as part of Goeyers, Charlotte & Vijver, Bart Van De, 2020, Revision of the non-marine centric diatom flora (Bacillariophyta) of the sub-Antarctic Campbell Island (southern Pacific Ocean) with the descriptions of five new species, pp. 1-30 in European Journal of Taxonomy 694 on pages 18-20, DOI: 10.5852/ejt.2020.694, http://zenodo.org/record/3973347

Angusticopula cosmica Goeyers & Van de Vijver sp. nov. http://phycobank.org/ 102315 Figs 28–43 Etymology The specific epithet refers to the general outlook of the valves in scanning electron microscopy giving the impression, due to the many granules, of a cosmos with numerous stars. Material examined Holotype CAMPBELL ISLAND • sub-Antarctic region; sample BAS303; 12 Jan. 1970; D. Vitt leg.; BR-4577. Isotype CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-368. Description Light microscopy (Figs 28–36) Frustules rectangular with valve diameter much larger than the mantle height. Cells always solitary; chains, even short ones, never observed. Numerous discoid plastids present. Valve diameter (n = 50): 18–45 μm, mantle height (n = 1): ca 8 μm. Valves with a low mantle and flat valve face. Internal valves never observed. Central area large, diameter 10–25 μm (50–60% of the total valve diameter, irregularly bordered by marginal striae. Marginal striae radial, clearly punctate, 31–35 in 10 μm, clearly visible in LM. Ring of rimoportulae visible close to the valve face/mantle junction (Fig. 35, arrows). Scanning electron microscopy (Figs 37–43) Girdle comprising a large number (up to 8) of narrow, open, non-perforated copulae (Fig. 37). Small ligulae filling the gaps created by the open copulae (Figs 37, arrows, 38). Mantle rather shallow, with dense uniseriate striation pattern, composed of very small, rounded areolae. Mantle edge with a constricted rim bordered by a serrate marginal edge (Figs 38, 39, double white arrows). Valve face/mantle junction gently sloping showing a shallow marginal ridge (Figs 39, black arrows, 40). Valves faces clearly flat (Fig. 40), entirely covered by irregularly scattered small granules (Figs 40–41). Central area weakly raised, clearly visible in oblique view (Fig. 37). Spines absent (Fig. 40). Valve face striation restricted to a broad marginal zone. Striae uniseriate, forming rather irregular series of small areolae bordered by a very shallow siliceous rim (Fig. 41). Internally, valves weakly dome-shaped (Fig. 42), perforated by a marginal pattern of small areolae, closed by individual hymenes. Areolae clearly arranged in striae, separated by very narrow interstriae. Irregular ring of rather large rimoportulae present near the mantle edge (Figs 42–43). Rimoportulae visible internally as short raised tubes (Fig. 43). Ecology and distribution Angusticopula cosmica sp. nov. was described from a Racopilum moss vegetation collected from a wet rock east of Moubray Hill. The sample was dominated by Frankophila dalevittii, a recently described endemic species for Campbell Island (Van de Vijver et al. 2020), Diatomella balfouriana and Diatomella colonialis Van de Vijver & Le Cohu. Class Coscinodiscophyceae Round & R.M.Crawford in Round et al. (1990) emend. Medlin & Kaczmarska Subclass Coscinodiscophycidae Round & R.M.Crawford in Round et al. (1990) Order Melosirales R.M.Crawford in Round et al. (1990) Family Melosiraceae Kütz. (Kützing 1844) emend. R.M.Crawford in Round et al. (1990) Genus Ferocia Van de Vijver et al., Published as part of Goeyers, Charlotte & Vijver, Bart Van De, 2020, Revision of the non-marine centric diatom flora (Bacillariophyta) of the sub-Antarctic Campbell Island (southern Pacific Ocean) with the descriptions of five new species, pp. 1-30 in European Journal of Taxonomy 694 on pages 6-9, DOI: 10.5852/ejt.2020.694, http://zenodo.org/record/3973347, {"references":["Van de Vijver B., Ballings P. & Goeyers C. 2020. Frankophila dalevittii, a new freshwater diatom (Bacillariophyta) from Campbell Island. Phytotaxa 429 (1): 57 - 64. https: // doi. org / 10.11646 / phytotaxa. 429.1.4","Round F. E., Crawford R. M. & Mann D. G. 1990. The Diatoms: Biology and Morphology of the Genera. Cambridge University Press, Cambridge.","Kutzing F. T. 1844. Die Kieselschaligen Bacillarien oder Diatomeen. Nordhausen."]}

Arcanodiscus indistinctus Goeyers & Van de Vijver sp. nov. http://phycobank.org/ 102319 Figs 81–96, 125–131 Etymology The specific epithet ‘ indistinctus ’ refers to the lack of any specific peculiarity of this species as a distinguishing feature. Material examined Holotype CAMPBELL ISLAND • sub-Antarctic region; sample BAS303; 12 Jan. 1970; D. Vitt leg.; BR-4580. Isotype CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-371. Description Light microscopy (Figs 81–96) Frustules discoid, almost square to rectangular with broadly rounded edges and convex valve faces. Frustules never seen attached to each other, always solitary. Multiple discoid chloroplasts present. Girdle bands not discernible in LM. Valves rather strongly silicified, rounded with a thick mantle and convex, weakly domed valve face. Valve dimensions (n = 25): valve diameter 9–17 μm, frustule height (n = 2): 7–9 μm. Central area comprising a large, smooth, hyaline zone, almost 75% of the total valve diameter, surrounded by a clearly striated marginal zone, 27–35 striae in 10 μm. Visible processes lacking. Scanning electron microscopy (Figs 125–131) Frustules discoid with very heavily silicified valves, visible as a thick mantle (Figs 125, 130). Girdle composed of several, narrow, non-perforated copulae (Fig. 126). Pars interior of the copulae clearly fimbriate giving the impression of perforate bands (Fig. 126). Valve face with large, flat hyaline, almost rounded central area, lacking areolae or any other ornamentation (Figs 127–128). Marginal zone gently sloping towards the mantle, entirely covered with short slit-like to almost rounded areolae (the latter when clearly eroded), ca 45 in 10 μm, roughly organized in irregular striae. Areolae externally covered by small, weakly raised, individual occlusions (Fig. 127). No obvious tube process openings apparent. Striae continuing over the valve face/mantle junction, interrupted by a series of up to 3 thin, parallel ridges running entirely around the mantle (Fig. 129). Irregular silica thickenings, often connected to the first marginal ridge, present at the valve face/mantle junction (Fig. 128, arrows). Mantle areolae small, clearly rounded. Mantle edge very narrow, irregularly bordered (Fig. 129). Internally, areolae large, each showing a clear rota, covered by very thin hymenes, organized in irregularly running striae (Fig. 130–131). Central area consisting of a large hyaline, irregularly bordered, central zone (Fig. 130). No thickened protuberances (called ‘portulae’) observed (Fig. 130). Mantle edge very broad, strongly silicified (Figs 130–131). Ecology and distribution Arcanodiscus indistinctus sp. nov. was described from a Racopilum moss vegetation collected from a wet rock east of Moubray Hill. The sample was dominated by by Frankophila dalevittii (Van de Vijver et al. 2020), Diatomella balfouriana and Diatomella colonialis. In the same sample, Arcanodiscus crawfordianus sp. nov. and Angusticopula cosmica sp. nov. were also observed. The presence in other samples needs to be confirmed with SEM observations., Published as part of Goeyers, Charlotte & Vijver, Bart Van De, 2020, Revision of the non-marine centric diatom flora (Bacillariophyta) of the sub-Antarctic Campbell Island (southern Pacific Ocean) with the descriptions of five new species, pp. 1-30 in European Journal of Taxonomy 694 on pages 16-18, DOI: 10.5852/ejt.2020.694, http://zenodo.org/record/3973347, {"references":["Van de Vijver B., Ballings P. & Goeyers C. 2020. Frankophila dalevittii, a new freshwater diatom (Bacillariophyta) from Campbell Island. Phytotaxa 429 (1): 57 - 64. https: // doi. org / 10.11646 / phytotaxa. 429.1.4"]}

Ferocia houkiana Goeyers & Van de Vijver sp. nov. http://phycobank.org/ 102316 Figs 44–73 Etymology The species is named in honour of our colleague and friend Dr Václav Houk (Institute of Botany, Czech Republic) to acknowledge him for his work on melosiroid diatoms. Material examined Holotype CAMPBELL ISLAND • sub-Antarctic region; sample BAS284; 12 Jan. 1970; D. Vitt leg.; BR-4578. Isotype CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-369. Description Light microscopy (Figs 44–62) Frustules rectangular. Cells connected via a central ring of spines, forming short chains. Numerous discoid plastids present. Girdle composed of large number of very narrow copulae, covering two adjacent valves. Valve diameter (n = 20): 4–11 μm, mantle height (n = 5): 4.0–5.5 μm. Valves with a relatively low mantle and rounded, flat valve face. Internal valves occasionally observed (Figs 50–51). Central area dominated by a regular crown of spines. Scattered spines present on the entire valve face. Striae not discernible in LM. Scanning electron microscopy (Figs 63–73) Girdle composed of a large number (up to 20) of narrow, open, non-perforated copulae (Fig. 63). Girdle bands attached to one of the valves of a cell extending over one of the new daughter valves after each cell division, meeting and overlapping with the bands attached to the other parent valve, covering that way two new valves of the daughter cells (Fig. 63). Copulae fimbriate on pars inferior giving the misleading impression of perforated girdle bands in non-eroded girdles (Figs 63, 65). Valves connected via central crown of large, wedge-shaped spines (Fig. 64). Müller step on mantle occasionally observed (Fig. 66, arrow). Mantle striae straight, composed of small, rounded areolae (Figs 64, 66). Near mantle edge, areolae very much smaller than near and at valve face/mantle junction, areolae irregularly scattered (Fig. 64). Mantle edge not rimmed. Rimoportula openings on the mantle not distinguishable from mantle areolae. Valve face/mantle junction thickened, relatively abrupt (Figs 63, 66). Valve face dominated by a central regular ring of large, relatively low, wedge-shaped spines (Figs 67–68). Spines hollow but apparently chambered with small silica walls inside the spines (Fig. 68). Spines occasionally lacking or reduced to series of low silica outgrowths (Fig. 69). Central area clearly raised, bordered by a narrow flat valve face edge, covered by an irregular pattern of small, rounded to slit-like areolae (Figs 67, 68, arrows). Striation pattern not detectable in the areolae. Internally, a few sessile rimoportula visible close to the mantle edge (Figs 71, 72, arrows), irregularly scattered. One rimoportula present near the valve center on the valve face (Figs 70, 73, arrow). Internal valve surface covered by numerous small areolae (Fig. 73). Ecology and distribution Ferocia houkiana sp. nov. is a frequently observed species on Campbell Island. It was found in several moss samples on rocks and next to waterfalls, usually dominated by species belonging to the genera Pinnularia, Pinnunavis and Eunotia. The type sample is dominated by the new species of Ferocia and is accompanied by Pinnularia borealis s. lat. Ehrenb. which points to a drier character of the environment, often influenced by sea spray (Van de Vijver et al. 2002).

Diatoms are useful ecological and paleolimnological indicators routinely used to reconstruct past conditions and monitor environmental change. Despite this, diatom assemblages from lake sediment cores are often difficult to interpret due to a limited knowledge of the ecology of some species, some of which may originate from the adjacent limno-terrestrial landscape. Here, we compare diatom assemblages from two recently published Antarctic lake sediment cores collected from the northeast and southwest sides of Vega Island, Antarctic Peninsula. We further compare the sediment core assemblages with adjacent modern communities inhabiting four different limno-terrestrial habitat types to gauge the importance of landscape connectivity in determining paleo-assemblage structure. We found that diatom assemblage composition was significantly different between the two cores, and our survey of modern habitats further revealed habitat type to be an important factor determining the composition of limno-terrestrial samples. Differences in modern habitats were driven primarily by Chamaepinnularia krookiformis in mosses, Nitzschia paleacea in ponds, and Fistulifera pelliculosa in streams. When modern communities were compared with paleo-assemblages through ordination, the cored lake from the northeast side, which exhibited greater hydrological connectivity with its surroundings, clustered more closely with the adjacent modern samples. Meanwhile, the cored lake from the southwest side, which was more hydrologically isolated, formed a distinct cluster separate from the others. Overall, species richness and diversity were greater on the southwest side of the island than the northeast, and the known distributions of diatom taxa supported the notion that Vega Island was a transitional zone between the Maritime and Continental Antarctic bioregions. These results collectively suggested that while environmental and spatial controls may be influential in determining diatom community composition, the unique hydrogeological setting of individual waterbodies was an important consideration for determining the assemblage structure of lake cores. This paper furthermore expanded ongoing research of diatom diversity and distributions on maritime Antarctic islands, which will improve diatom-based interpretations for regional ecological monitoring and paleolimnology in the future.

Very recently, several new diatom taxa have been described living epizoically on sea turtles. Among them, two new genera, Poulinea Majewska & al. and Chelonicola Majewska & al. (Majewska & al. 2015), described from nesting olive ridleys in Costa Rica, were later observed in multiple samples collected from other sea turtle species from different geographic locations across the globe. Both genera possess cuneate, heteropolar frustules, morphologically (though not necessarily genetically) resembling other gomphonemoid diatom taxa, most notably Tripterion R. W. Holmes & al. (Holmes & al. 1993), a genus described from the skin of Dall’s porpoises and later found growing on other marine mammals (whales) but also on abiotic substrates (Fernandes & Sar 2009). Several inconsistencies in the current description of Tripterion have been highlighted (Fernandes & Sar, 2009, Frankovich & al. 2016) and Riaux-Gobin & al. (2017) further questioned the description of Poulinea, indicating incorrect character coding used in the cladistic analysis applied by Majewska & al. (2015) to differentiate Poulinea from Tripterion. Although Riaux-Gobin & al. (2017) noted that the small sea turtle- associated diatoms they examined showed a relatively simple morphology and a certain level of morphological variability, another two, morphologically very similar, taxa were described as Chelonicola caribeana Riaux-Gob. & al. and Tripterion societate ‘societatis’ Riaux-Gob. & al., the latter being almost indistinguishable from the previously described Poulinea lepidochelicola Majewska & al. The current study characterizes over 20 populations of epizoic “gomphonemoid” diatoms found on five sea turtle species inhabiting all three oceans, highlighting both the remarkable morphological plasticity found within each of these populations and the lack of morphological discontinuity among them. As diatom epibiosis on sea turtles (and other marine and freshwater animals) attracts growing attention, further new forms are expected to be discovered in on- going surveys, and it must emphasized that, especially in the case of these small-celled heteropolar specimens, new taxa should be described with extreme caution.

Luticola ivetana Chattová & Van de Vijver sp. nov. Figs 27‒43 Etymology The new species was named after Mrs. Iveta Chattová, mother of the first author, on the occasion of her 50th birthday. Type ILE AMSTERDAM: Entrecasteaux, TAAF, sub-Antarctica, 37°51′18.6″ S, 77°31′23.5″ W, 21 Dec. 2016, B. Van de Vijver sample W030 (holo-: slide no. BR‒4495, Fig. 27; iso-: slide PLP ‒330; University of Antwerp, Belgium). Description Light microscopy (Figs 27–36) Valves elliptic-lanceolate with convex margins and broadly rounded, non-protracted apices. Valve dimensions (n = 50): length 11.0‒25.5 µm, valve width 6.0‒7.5 µm. Axial area narrow, linear, almost not widening towards the apices and central area. Central area forming a bow-tie shaped stauros. One isolated pore present in the central area, positioned close to the valve centre. Raphe filiform, straight with weakly deflected simple proximal raphe endings and elongated terminal raphe fissures. Striae radiate throughout the entire valve, 16‒18 in 10 µm. Scanning electron microscopy (Figs 37–43) Striae composed of 2–4 round to elongated areolae, clearly enlarged near the central area and the valve margins (Figs 37, 43). Mantle areolae very large, rounded, never slitlike (Fig. 39). Central area bordered by 1–2 rounded to weakly transapically elongated areolae. Isolated pore elliptic, clearly isolated from the central striae (Fig. 38). Raphe branches straight with short proximal raphe endings bent towards the side with the isolated pore (Fig. 42). Terminal raphe fissures hooked, continuing onto the valve mantle (Fig. 41). Internally, poroids of valve face occluded by hymens forming a continuous strip on each stria. Distinct stauros visible. Internal proximal raphe endings straight, terminating on the edge of the stauros. Distal raphe endings terminating onto small helictoglossae (Fig. 40). Ecology and distribution So far, L. ivetana sp. nov. was observed on Ile Amsterdam only. The type locality where a large population of this new species was observed, was a small crack in a rock face at Entrecasteaux, clearly under the permanent influence of seaspray. A very thin film of water was present in the crack together with wet mud. The sample was taken by scraping off the mud and the water from the crack. Another large population where L. ivetana sp. nov. was found is a lava cavern in the partly collapsed Grand Tunnel, running from the Cratères Vénus to the northern coast. The sample was taken from wet mosses (F-value IV-V), growing on the wall of the cavern, close to the entrance, in a population of Blechnum australe L. The sample was dominated by Ferocia setosa (Greville) Van de Vijver & Houk (Van de Vijver et al. 2017), Orthoseira verleyenii Van de Vijver (Lowe et al. 2013), Sellaphora barae Van de Vijver & E.J.Cox (Van de Vijver & Cox 2013) and various Humidophila species.

Luticola beyensii Van de Vijver, Ledeganck & Lebouvier Figs 1���12 Diatom Research 17: 235���241 (Van de Vijver et al. 2002b). Type ILE SAINT PAUL: TAAF, sub-Antarctica, 16 Dec. 1999, B. Van de Vijver sample A9 (holo-: CAS 220051, California Academy of Science; iso-: slide no. BR ���4045, University of Antwerp, Belgium). Description Light microscopy (Figs 1���10) Valves rhombic-lanceolate with clearly convex margins. Larger individuals with more or less rostrate apices, in smaller specimens apices more broadly rounded. Valve dimensions (n = 25): length 14.5��� 22.0 ��m, width 6.0���8.5 ��m. Axial area relatively narrow, linear. Central area with a large fascia, rarely reaching the valve margins, due to a series of small areolae bordering the central area near the margins. Isolated pore solitary, round, located close to the valve margin, never connected to a stria. Raphe filiform, straight, with simple, bent proximal raphe endings, away from the isolated pore. Terminal raphe fissures clearly hooked. Striae weakly radiate near the central area, becoming more radiate towards the apices, 22���24 in 10 ��m. Areolae well visible in LM. Scanning electron microscopy (Figs 11���12) Striae composed of 2���4 rounded areolae (Figs 11���12). Occasionally areolae fused within one stria forming transapically enlarged areolae (Fig. 11). Terminal raphe fissures clearly hooked, first deflected towards the side opposite the isolated pore, then hooked into the other side, weakly continuing onto the valve mantle (Fig. 12). Ecology and associated diatom flora Luticola beyensii was found in relatively dry, bare soils and on dry mosses (F-value VII-VIII) on both islands. The samples with L. beyensii were dominated by several taxa of the genus Humidophila R.L.Lowe et al. [Humidophila contenta (Grunow) R.L. Lowe et al. (Lowe et al. 2014), Humidophila brekkaensis (J.B.Petersen) R. L. Lowe et al. (Lowe et al. 2014)], and Pinnularia borealis Ehrenb. (Ehrenberg 1843) and Hantzschia amphioxys (Ehrenb.) Grunow (Cleve & Grunow 1880)., Published as part of Chattov��, Barbora, Lebouvier, Marc, Haan, Myriam De & Vijver, Bart Van De, 2017, The genus Luticola (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean) with the description of two new species, pp. 1-17 in European Journal of Taxonomy 387 on pages 3-5, DOI: 10.5852/ejt.2017.387, http://zenodo.org/record/1133653, {"references":["Van de Vijver B., Ledeganck P. & Lebouvier M. 2002 b. Luticola beyensii sp. nov., a new aerophilous diatom from ile Saint Paul (Indian Ocean, TAAF). Diatom Research 17: 235 - 241. https: // doi. org / 10.1080 / 0269249 X. 2002.9705541","Lowe R. L., Kociolek J. P., Johansen J. R., Van de Vijver B., Lange-Bertalot H. & Kopalova K. 2014. Humidophila gen. nov., a new genus for a group of diatoms (Bacillariophyta) formerly within the genus Diadesmis: species from Hawai'i, including one new species. Diatom Research 29: 351 - 360. https: // doi. org / 10.1080 / 0269249 X. 2014.889039","Ehrenberg C. G. 1843. Verbreitung und Einfluss des mikroskopischen Lebens in Sud-und Nord-Amerika. Abhandlungen der Koniglichen Akademie der Wissenschaften zu Berlin 1841: 291 - 466.","Cleve P. T. & Grunow A. 1880. Beitrage zur Kenntniss der arctischen Diatomeen. Kongliga Svenska Vetenskaps-Akademiens Handlingar ser. 4 17 (2): 1 - 121."]}

Luticola vancampiana Chattov�� & Van de Vijver sp. nov. Figs 44���71 Etymology The species is named after Prof. Dr. Karel Van Camp (University of Antwerp, Belgium), to thank him for his efforts in conserving the Van Heurck Collection and his broad interest in diatom research. Type ILE SAINT-PAUL: Conserverie, TAAF, sub-Antarctica, 38��42���52.0��� S, 77��31���55.5��� W, 24 Nov. 2016, B. Van de Vijver sample S029 (holo-: slide no. BR���4496, Fig. 47; iso-: slide PLP���331; University of Antwerp, Belgium). Description Light microscopy (Figs 44���67) Valves linear-lanceolate to elliptic-lanceolate, elliptic in the smallest specimens, with protracted, subcapitate to rostrate apices. In smaller specimens, valve ends not as protracted, only subrostrate or obtusely rounded. Initial cells rhombic-lanceolate. Valve dimensions (n = 35): length 10.0���26.0 ��m, width 5.0���8.5 ��m. Axial area linear, narrow. Single, rounded isolated pore present in the central area, located halfway between the valve centre and margin, sometimes attached to a stria. Central area wide, bow���tie shaped, bordered on both sides with a series of 3���5 round areolae. Raphe branches straight, Figs 44���71. Luticola vancampiana Chattov�� & Van de Vijver sp. nov. Light (LM) and scanning electron micrographs (SEM) from the type population from Conserverie on Ile Saint-Paul, B. Van de Vijver sample S029. 44���67. LM showing the variation in size and shape of the valve apices. 68���69. SEM of valve exterior. 70. SEM of valve interior. 71. SEM girdle view. Scale bars: 44���67 10 ��m; 68���71 = 5 ��m. deflected away from the isolated pore at both proximal and distal ends. Transapical striae radiate throughout, 16���19 in 10 ��m. Scanning electron microscopy (Figs 68���71) Valve mantle with a single row of round areolae (Fig. 71), interrupted at the apices. Striae composed of 3���4 areolae, 1���2 areolae at the apices. Areolae round to elongated, clearly enlarged and prolonged close to the valve margins (Fig. 68). Internally, areolae occluded by hymens, forming a continuous strip across the valve (Fig. 70). Isolated pore showing an elliptic external opening. Internally, central nodule thickened, expanding into stauros. Isolated pore with semi-lunar opening formed by tonguelike structure. Raphe branches straight. Proximal raphe endings short, deflected to side opposite to the isolated pore. Terminal raphe fissures deflected to the same side as the proximal endings, not extending onto the mantle (Fig. 69). Internally, proximal raphe endings straight, while distally, raphe branches terminating on small helictoglossae. Ecology and distribution So far L. vancampiana sp. nov. was found on both IleAmsterdam and Ile Saint-Paul.The largest population was found in a wet soil covered by green algae close to the ocean on Ile Saint-Paul. The sampling site is frequently visited by fur seals and penguins, as was visible in the macroremains (feathers, excrements). The sample was almost entirely dominated by the new Luticola species. Other (smaller) populations were found in soil samples collected near penguin rookeries where similar conditions (considerable biotic influence, considerable salinity input) prevailed., Published as part of Chattov��, Barbora, Lebouvier, Marc, Haan, Myriam De & Vijver, Bart Van De, 2017, The genus Luticola (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean) with the description of two new species, pp. 1-17 in European Journal of Taxonomy 387 on pages 8-10, DOI: 10.5852/ejt.2017.387, http://zenodo.org/record/1133653

Luticola sp. Figs 72‒82 Description Light microscopy (Figs 72–82) Valves linear-lanceolate to elliptic-lanceolate in smaller specimens, with rounded, non-protracted apices. Valve dimensions (n = 12): length 10.7‒20.5 µm, width 4.5‒6.5 µm. Axial area narrow, linear. Central area wide, bow-tie shaped, clearly asymmetrical with the side bearing the isolated pore markedly wider. Isolated pore present in the central area, located halfway between the valve centre and margin. Raphe branches straight, deflected away from the isolated pore at both proximal and distal ends. Transapical striae punctate, radiate throughout the entire valve, 20‒24 in 10 µm. Remarks So far, this species has only been observed with light microscopy. Further studies and SEM observations will be necessary to determine its correct taxonomic position. The species was so far found in only two soil samples (A6 and A7) taken from Ile Saint-Paul. Both samples are dominated by L. beyensii, Humidophila brekkaensis, Pinnularia acidicola Van de Vijver & Le Cohu (Van de Vijver et al. 2002 a) and Hantzschia amphioxys.

Luticola vancampiana Chattová & Van de Vijver sp. nov. Figs 44‒71 Etymology The species is named after Prof. Dr. Karel Van Camp (University of Antwerp, Belgium), to thank him for his efforts in conserving the Van Heurck Collection and his broad interest in diatom research. Type ILE SAINT-PAUL: Conserverie, TAAF, sub-Antarctica, 38°42′52.0″ S, 77°31′55.5″ W, 24 Nov. 2016, B. Van de Vijver sample S029 (holo-: slide no. BR‒4496, Fig. 47; iso-: slide PLP‒331; University of Antwerp, Belgium). Description Light microscopy (Figs 44–67) Valves linear-lanceolate to elliptic-lanceolate, elliptic in the smallest specimens, with protracted, subcapitate to rostrate apices. In smaller specimens, valve ends not as protracted, only subrostrate or obtusely rounded. Initial cells rhombic-lanceolate. Valve dimensions (n = 35): length 10.0‒26.0 μm, width 5.0‒8.5 μm. Axial area linear, narrow. Single, rounded isolated pore present in the central area, located halfway between the valve centre and margin, sometimes attached to a stria. Central area wide, bow–tie shaped, bordered on both sides with a series of 3–5 round areolae. Raphe branches straight, Figs 44–71. Luticola vancampiana Chattová & Van de Vijver sp. nov. Light (LM) and scanning electron micrographs (SEM) from the type population from Conserverie on Ile Saint-Paul, B. Van de Vijver sample S029. 44–67. LM showing the variation in size and shape of the valve apices. 68–69. SEM of valve exterior. 70. SEM of valve interior. 71. SEM girdle view. Scale bars: 44–67 10 µm; 68‒71 = 5 µm. deflected away from the isolated pore at both proximal and distal ends. Transapical striae radiate throughout, 16‒19 in 10 µm. Scanning electron microscopy (Figs 68–71) Valve mantle with a single row of round areolae (Fig. 71), interrupted at the apices. Striae composed of 3–4 areolae, 1–2 areolae at the apices. Areolae round to elongated, clearly enlarged and prolonged close to the valve margins (Fig. 68). Internally, areolae occluded by hymens, forming a continuous strip across the valve (Fig. 70). Isolated pore showing an elliptic external opening. Internally, central nodule thickened, expanding into stauros. Isolated pore with semi-lunar opening formed by tonguelike structure. Raphe branches straight. Proximal raphe endings short, deflected to side opposite to the isolated pore. Terminal raphe fissures deflected to the same side as the proximal endings, not extending onto the mantle (Fig. 69). Internally, proximal raphe endings straight, while distally, raphe branches terminating on small helictoglossae. Ecology and distribution So far L. vancampiana sp. nov. was found on both IleAmsterdam and Ile Saint-Paul.The largest population was found in a wet soil covered by green algae close to the ocean on Ile Saint-Paul. The sampling site is frequently visited by fur seals and penguins, as was visible in the macroremains (feathers, excrements). The sample was almost entirely dominated by the new Luticola species. Other (smaller) populations were found in soil samples collected near penguin rookeries where similar conditions (considerable biotic influence, considerable salinity input) prevailed.