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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.

In this paper we describe in detail the procedure for a genomic DNA extraction method from spores of myxomycetes that was inspired by the direct PCR technique. We include results of small-scale tests that were set up for the optimization of this extraction method. These tests were performed to select the grinding breads, assess the result of different estimated spore quantities, compare the extraction medium, evaluate the temperature to weaken the cell walls of amoeboflagellates, and to ascertain whether the storage method of the extract is appropriate. The results are presented as agarose gel images of either crude genomic DNA extracts or PCR products of partial SSU and are discussed in detail. From the tests the following combination was withheld: extraction solution TE pH: 8, grinding with 1 mm Zirconia/Silica beads during 60 sec at 30 Hz, cell weakening at 90°C and storage at -20°C. The specimens that were used for the tests are listed in this paper along with collection data and the GenBank accession numbers for the submitted SSU sequences. This simple approach can serve as a fast, cheap, and cleaner alternative to other extraction protocols, or it can be used as a preparation phase for such established methods.

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)., 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 page 12, DOI: 10.11646/phytotaxa.572.1.1, http://zenodo.org/record/7305672, {"references":["Peragallo, M. (1921) Diatomees d'eau douce et diatomees d'eau salee. In: Deuxieme Expedition Antarctique Francaise (1908 - 1910) commandee par le Dr. Jean Charcot. Sciences Naturelles, Documents Scientifiques, Botanique, Masson et Cie, pp. 96 + Pl. https: // doi. org / 10.5962 / bhl. title. 64272","Williams, D. M. (1988) Tabulariopsis, a new genus of marine araphid diatom, with notes on the taxonomy of Tabularia Williams et Round. Nova Hedwigia 47: 247 - 254.","Frenguelli, J. & Orlando, H. A. (1958) Diatomeas y silicoflagelados del sector Antartico Sudamericano. Instituto Antartico Argentino Publicacion No. 5: 1 - 191.","Fernandes, L. F. & Sar, E. A. (2009) Fine morphology of Gomphonema margaritae Frenguelli & Orlando and its validation and transfer to Tripterion Holmes, Nagasawa & Takano. Diatom Research 24: 63 - 78. https: // doi. org / 10.1080 / 0269249 X. 2009.9705783"]}

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

This is an article honoring the life of Prof. Dr. Indira Kalyanasundaram (1939-2021)

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.

Luticola ivetana Chattov�� & Van de Vijver sp. nov. Figs 27���43 Etymology The new species was named after Mrs. Iveta Chattov��, 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 ��m, valve width 6.0���7.5 ��m. 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 ��m. 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 Crat��res V��nus 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., 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 6-8, DOI: 10.5852/ejt.2017.387, http://zenodo.org/record/1133653, {"references":["Chattova B., Lebouvier M. & Van de Vijver B. 2017. Morphological and taxonomical analysis of the terrestrial diatom genus Humidophila (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean). Phytotaxa (in press).","Lowe R. L., Kociolek J. P. & Van de Vijver B. 2013. Two new Orthoseira species (Bacillariophyceae) from lava tubes on Ile Amsterdam and Big Island (Hawaii). Phytotaxa 111: 39 - 52. https: // doi. org / 10.11646 / phytotaxa. 111.1.3"]}

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 ��m, width 4.5���6.5 ��m. 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 ��m. 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., 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 10-11, DOI: 10.5852/ejt.2017.387, http://zenodo.org/record/1133653, {"references":["Van de Vijver B., Frenot Y. & Beyens L. 2002 a. Freshwater diatoms from Ile de la Possession (Crozet Archipelago, Subantarctica). Bibliotheca Diatomologica 46: 1 - 412."]}

Luticola subcrozetensis Van de Vijver, Kopalov��, Zidarova & Levkov Figs 13���26 Diatoms of Europe: Diatoms of the European Inland Waters and Comparable Habitats 7: 228, pl. 46 figs 15���31, pl. 47 figs 4���6 (Levkov et al. 2013). Type ILE DE LA POSSESSION: Crozet Archipelago, sub-Antarctica, 5 Dec. 1999, B. Van de Vijver (holo-: slide no. BR ���4290; iso-: slides BRMZU 9 /25, MKNDC 006278 / B). Description Light microscopy (Figs 13���22) Valves rhombic-lanceolate to elliptic-lanceolate and even elliptic in smaller specimens with clearly convex margins and broadly rounded, non-protracted apices. Valve dimensions (n = 25): length 12��� 29 ��m, width 7.0���8.5 ��m. Axial area linear, slightly widening towards apices and central area. Central area bow-tie shaped, wider opposite the isolated pore, bordered by shortened striae on both sides. An isolated pore present in the central area, located halfway between the valve centre and the valve margin. Raphe branches straight, bent away from the isolated pore at both proximal and distal ends. Striae radiate throughout the entire valve, 15���17 in 10 ��m. Scanning electron microscopy (Figs 23���26) Striae composed of 3���5 small, rounded to slightly elongated areolae at the apices, only 1���2 rounded areolae per stria, extending past the terminal raphe fissures on the valve face (Fig. 23). A single row of rounded areolae present along entire valve mantle, interrupted at apices (Fig. 26). Isolated pore rounded, slightly elongated, not associated with a stria. Central area usually bordered by one, rarely two, series of small, rounded areolae. Raphe branches straight to slightly curved. Proximal raphe endings bent to the side opposite the isolated pore, terminating into weakly developed pores. Terminal raphe fissures bent to the same side as the proximal endings terminating on the valve face, not extending onto the mantle (Fig. 24). Ecology and distribution Luticola subcrozetensis is a typical sub-Antarctic and Maritime Antarctic species. Originally described from Ile de la Possession (Crozet archipelago), the species was also reported from Livingston Island (Zidarova et al. 2016), one of the major South Shetland Islands, located in the southern Atlantic Ocean. The species was recently found in moss samples from Gough Island (Vin��ov��, unpubl. res.). It was present in samples from both Ile Saint-Paul and Ile Amsterdam. The largest population was observed in a soil sample collected near the rockhopper penguin rookery of Ile Saint-Paul, at an altitude of 110 m, hidden in cracks in the rocks that border the penguin rookery., 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 5-6, DOI: 10.5852/ejt.2017.387, http://zenodo.org/record/1133653, {"references":["Levkov Z., Metzeltin D. & Pavlov A. 2013. Diatoms of Europe: Diatoms of the European Inland Waters and Comparable Habitats. Vol. 7. Koeltz Scientific Books, Koningstein.","Zidarova R., Kopalova K. & Van der Vijver B. 2016. Diatoms from the Antarctic region: maritime Antarctica. Iconographia Diatomologica 24: 1 - 504."]}

Friedrich Kützing originally used the name Tabularia as a subgenus of Synedra. He included eleven species and one variety, most of which were found in marine or brackish realm. Williams & Round (1986) considered the subgenus better treated as a genus and transferred four species into it, with T. barbatula as typus generis. Three distinct morphological groups were separated within Tabularia, based on morphological features, and subsequent work shows it to be a paraphyletic assemblage. In addition, a large number of taxa have been described as new for the genus or transferred into it. The large morphological variation demands the need for a revision of the genus. One way to better document this variability is to investigate the original material of historic diatom collections, mainly from the nineteenth century. One of the larger collections containing members of the genus Tabularia, is the William Smith collection, mainly conserved in Meise Botanic Garden (Belgium) and the Natural History Museum in London (UK). Reverend Williams Smith's two-volume monograph A synopsis of the British Diatomaceae, published in 1853 and 1856, has been the most comprehensive work on British diatoms for over a century. The monograph was based on a large collection of UK samples collected by Smith in collaboration with various national and international phycologists. Smith described and/or documented many new taxa, including several Synedra species, nowadays placed in Tabularia. The present poster will illustrate the different Tabularia taxa found in the William Smith Collection that is housed in Meise Botanic Garden. Based on observations of different Tabularia taxa, we will indicate how the genus Tabularia may be revised, making our study an incentive for further research on the genus. Overall, the study highlights the importance of careful analysis and revision of original material when making taxonomic transfers. This study will provide valuable insights into the diversity of Tabularia and highlight the need for a revision of the genus.

Sea turtles are known for a long time as a habitat for numerous and diverse microbes that happily live on the external and internal surfaces of their different body parts. Shells are especially known to be often covered with various macroepibionts and colourful biofilms formed by diatoms and bacteria. These microbes can be specialized and found almost exclusively associated with sea turtles but also opportunistic and found elsewhere in the turtle environment. In this presentation I am going to show you an overview of results obtained by research conducted within the TurtleBIOME project running in the period of 2018-2023 that involved a lot of very enthusiastic and dedicated participants and we are extremely thankful for their involvement. The main focus of our research was to characterize the microbial communities found in both the external (skin and shell) and the internal (gut, cloaca, oral cavities) habitats provided by loggerheads. We chose this species of sea turtle (Caretta caretta) as it is the most common turtle species in the Mediterranean Sea. We collected microbial samples from >120 animals from several locations in the Mediterranean area (Pula, Vis, and Lošinj in Croatia, Bari in Italy, and Amvrakikos Bay and Rethymnos in Greece) and analysed them using amplicon profiling with 16S, 18S, rbcL and ITS as molecular markers. The collected carapace and skin biofilm samples were also analysed using classical microscopical approach and that resulted in the description of several new diatom species. We have also isolated, identified, and maintained ca. 200 non-axenic diatom strains, which were then used in several experiments investigating the ecological preferences of diatoms themselves and their associated bacterial partners. We characterized the bacterial community of turtle-associated diatoms using metabarcoding and cultivation approach. This presentation will summarize these and other results we obtained while exploring the prokaryotic and microeukaryotic communities of loggerheads. Our multidisciplinary investigations provide the first inventory of loggerhead sea turtle endo- and epimicrobiota, revealing high diversity, different levels of host fidelity, and local biogeography of sea turtle associated microbes.