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1 Phytotaxa 170 (3): ISSN (print edition) Copyright 2014 Magnolia Press Article PHYTOTAXA ISSN (online edition) Four new Luticola taxa (Bacillariophyta) from Maritime Antarctica RALITSA ZIDAROVA 1,*, ZLATKO LEVKOV 2 & BART VAN DE VIJVER 3,4 1 St. Kliment Ohridski University of Sofia, Faculty of Biology, Department of Botany, 8 Dragan Tzankov Blvd., Sofia 1164, Bulgaria zidarova.r@gmail.com (*author for correspondence) 2 Institute of Biology, Faculty of Natural Sciences, Gazi Baba bb, Skopje, R. Macedonia E mail: zlevkov@iunona.pmf.ukim.edu.mk 3 Botanic Garden Meise, Department of Bryophyta & Thallophyta, Nieuwelaan 38, B-1860 Meise, Belgium vandevijver@br.fgov.be 4 University of Antwerp, Department of Biology, ECOBE, Universiteitsplein 1, B-2610 Wilrijk, Antwerpen, Belgium Abstract The paper describes four new Luticola taxa from the South Shetland Archipelago, Antarctica: Luticola neglecta sp. nov., L. bogaertsiana sp. nov., L. contii sp. nov. and L. olegsakharovii sp. nov. All new taxa are studied using both light and scanning electron microscopy and compared to other morphologically similar species from (sub-)antarctica and elsewhere in the world. Data on their ecology and biogeography are added. Key words: Antarctic Region, Bacillariophyta, Luticola, new species, morphology, taxonomy Introduction Species of the genus Luticola D.G.Mann in Round et al. (1990: 670) are substantial constituents of the Antarctic non-marine diatom communities and the genus often dominates Antarctic terrestrial habitats (Kopalová et al. 2011, Van de Vijver et al. 2011). Recent studies in the Antarctic region clearly showed that as for many other genera such as Stauroneis Ehrenberg (1843: 45) [Van de Vijver et al. 2005], Muelleria (Frenguelli) Frenguelli (1945: 172) [Van de Vijver et al. 2010], Hantzschia Grunow (1877: 174) [Zidarova et al. 2010], Pinnularia Ehrenberg (1843: 45) [Van de Vijver & Zidarova 2011, Zidarova et al. 2012] and Eunotia Ehrenberg (1837: 44) [Van de Vijver et al. in press], the diversity of the genus Luticola in Antarctica has been greatly underestimated in the past, mostly due to the lack of appropriate literature for the identification of the Antarctic diatoms that inevitably led to force-fitting (Tyler 1996) the Antarctic Luticola taxa into infra-specific taxa of the well-known Luticola muticopsis (Van Heurck) D.G.Mann in Round et al. (1990: 671), L. mutica (Kützing) D.G.Mann in Round et al. (1990: 671) and/or L. cohnii (Hilse) D.G.Mann in Round et al. (1990: 670). During the past decade the scientists working in Antarctica begun to adopt and apply a more refined taxonomy that allowed the recognition and description of many new Luticola species from the region (i.e. Van de Vijver et al. 2006, 2011, Esposito et al. 2008, Van de Vijver & Mataloni 2008, Kopalová et al. 2009, 2011, Levkov et al. 2013). At present, almost 40 Luticola species are known from the entire sub-antarctic region, and 26 of these are present in and even unique for the Maritime Antarctic, making it one of the most diverse and species rich diatom genera in these latitudes. This paper describes four new Luticola taxa observed on the islands of the South Shetland Archipelago. During a survey of limno-terrestrial diatoms on several islands, one Luticola species could not be identified using the currently available literature and it is described here as new: L. neglecta sp. nov. New and more complete studies of the morphology of another taxon, earlier identified and reported as L. binodis (Hustedt) M.B.Edlund in Edlund et al. (2001: 85) by Van de Vijver et al. (2011: 149, figs 46 48), showed that it is not conspecific with the latter and has to be separated as an independent taxon: Luticola bogaertsiana sp. nov. Finally, an extensive and detailed morphological analysis was done on several populations of Luticola nivalis (Ehrenberg) D.G.Mann in Round et al. (1990: 671) on the South Shetland Islands. As a result, it became clear that what was previously identified as L. nivalis on these islands (i.e. Van de Vijver & Mataloni 2008, Zidarova 2008) represented actually two taxa: L. contii sp. nov. and L. olegsakharovii sp. nov. For all new taxa detailed morphological descriptions are provided and their ecology, biogeography and separation from similar taxa are discussed. Accepted by Patrick Kociolek: 25 Apr. 2014; published: 26 May

2 Study area The South Shetland Islands (63 00 S, W) are a series of 11 larger and many smaller islands and islets located north of the Antarctic Peninsula (Fig. 1). The islands belong to the Maritime Antarctic Province (Chown & Convey 2007) and have a typical maritime oceanic climate with mean annual temperatures around -5 C, high precipitation rates and strong westerly winds (Toro et al. 2007). Most of islands are covered by permanent ice and snow leaving only small parts mainly on the coastal areas ice-free in summer. The vegetation on the islands is limited to lichens and mosses with only two flowering plants. FIGURE 1. Map of the region showing A. the location of the South Shetland Islands and B. the position of Deception Island, King George Island and Livingston Island within the South Shetland Islands. Material and methods During several Antarctic campaigns ( ) diatom samples were collected from various limno-terrestrial habitats on three main islands of the South Shetland Archipelago: King George Island, Livingston Island and Deception Island (Fig. 1). Diatom samples were prepared for analysis following the method described in Hasle & Fryxell (1970): Small subsamples were cleaned using concentrated H 2 SO 4 followed by the addition of KMnO 4. The samples were then bleached with H 2 C 2 O 4 and washed several times with distilled water. Cleaned diatom valves were mounted in Naphrax. The slides were analyzed using a BX53 light microscopes (LM) equipped with Differential Interference Contrast (Nomarski) and Olympus digital camera. For Scanning Electron Microscopy (SEM), part of the suspension was filtered through polycarbonate membrane filters with a pore diameter of 1 µm, pieces of which were fixed on aluminum stubs after airdrying. The stubs were sputter-coated with 20 nm of Au-Pd and studied in a Zeiss Ultra microscope at 3 kv at the Natural History Museum (London, UK), except for figures 63 & 64, where observations were done at 20 kv in JEOL-5800LV SEM at the Botanic Garden Meise (Belgium). Samples and slides are stored at the BR-collection, property of the Belgian federal government and given in permanent loan to the Botanic Garden Meise (Belgium) and at the Faculty of Biology, University of Sofia (Bulgaria). The isotypes are sent to The Friedrich Hustedt Diatom Study Centre (BRM). 156 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

3 Morphological terminology follows Hendey (1964), Round et al. (1990), Van de Vijver & Mataloni (2008) and Levkov et al. (2013). The morphology of the new species has been compared with known Luticola species from the Antarctic region and elsewhere in the world using the following literature: Rumrich et al. (2000), Metzeltin et al. (2005), Van de Vijver & Mataloni (2008), Kopalová et al. (2009, 2011), Van de Vijver et al. (2011), Levkov et al. (2013). The main discriminative features between the new species and their morphologically similar taxa are summarized in Tables 1 3. Descriptions of new taxa Luticola neglecta sp. nov. (Figs 2 20) Type: ANTARCTICA. South Shetland Islands: Deception Island, Sample D37, leg. R. Zidarova, coll. date 24/01/2013, slide no. BR (holotype), slide PLP-253 (isotype University of Antwerp, Belgium), BRM-ZU9/67 (isotype BRM). Etymology: The specific epithet refers to the fact that this species has been confused with other taxa and therefore neglected as a separate species (Latin: neglectus = neglected, overlooked). FIGURES Luticola neglecta Zidarova, Levkov & Van de Vijver, sp. nov. Light (LM) and scanning electron microscope (SEM) micrographs: Figs 2, LM of 18 valves from the type population, Deception Island, sample D37 (scale bars = 10 µm). Fig. 20. SEM external view of a valve from the type population, Deception Island, sample D37 (scale bar = 5 µm). Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 157

4 Valves lanceolate to elliptic-lanceolate with convex margins and rounded apices. Valve length µm, width µm. Axial area narrow, linear to linear-lanceolate. Raphe straight with weakly deflected proximal raphe endings and distal raphe fissures hooked towards the pore-bearing side. Central area with one isolated pore, bow-tie shaped, often asymmetrically enlarged, bordered on each side by 3 4 short striae. Striae moderately radiate in the middle, more radiate toward the apices, in 10 µm. Ecology and distribution: Luticola neglecta has up to now only been observed on Deception Island in two samples, one collected from soil and one taken among almost dry moss, growing in a crack of coastal rocks under moderate nutrient input of birds and higher salinity levels due to the vicinity of the sea. Accompanying taxa included Pinnunavis gebhardii (Krasske) Van de Vijver in Van de Vijver et al. (2002: 77) and several other Luticola species. It is likely that the species is more widespread on the islands or even in Antarctica but it has been overlooked or misidentified in the past. LM observations: (Figs 2 19): Larger valves are lanceolate with convex margins and weakly produced, rounded apices whereas smaller valves are more elliptic-lanceolate to even rhombic-lanceolate with convex margins and broadly rounded apices. Valve dimensions (n=24): length µm, width µm. The axial area is narrow, linear to linear-lanceolate, weakly widening towards the central area. The central area is enlarged into a bowtie shaped stauros, often asymmetrical because wider on the side opposite the isolated pore. In most valves, the central area is bordered on each side by 3 4 shortened striae composed of one single areola. One rounded isolated pore is present in the central area, located closer to the valve margin and not associated with a stria. The raphe is straight with almost inconspicuous proximal raphe endings that are weakly deflected opposite the isolated pore. The distal raphe fissures are visible in larger valves (Figs 2, 4, 7, 8), elongated and hooked towards the pore-bearing side. The striae are moderately radiate in the valve middle, and become more radiate towards the apices, in 10 µm. SEM observations: (Fig. 20): The striae are composed of usually 2, occasionally 3 irregularly spaced, small, rounded to weakly transapically elongated areolae. The isolated pore is small and rounded. The proximal raphe endings are first weakly deflected -bearing side and then hook shortly towards the pore. Irregular, thread-like shallow depressions are present next to the proximal raphe endings. The distal raphe fissures are elongated and hooked towards the pore bearing side, reach the mantle and extend slightly onto it. One row of rounded areolae, interrupted at the valve poles, is present on the mantle. Similar species: A large number of Luticola taxa share a similar valve outline (Table 1) but none of the already known species possesses the same unique combination of raphe structure, areolae and striation pattern present in L. neglecta. In LM L. neglecta can be confused with several typical Antarctic taxa: L. australomutica Van de Vijver in Van de Vijver & Mataloni (2008: 458), L. quadriscrobiculata Van de Vijver in Van de Vijver & Mataloni (2008: 457), L. pusilla Van de Vijver, Kopalová, Zidarova & Levkov in Levkov et al. (2013: 203) and L. delicatula Van de Vijver, Kopalová, Zidarova & Levkov in Levkov et al. (2013: 99). Luticola pusilla is easily separated by its broader valves with rather wide, lanceolate axial area, short distal raphe fissures that are weakly deflected -bearing side and lower number of striae (Table 1). Luticola quadriscrobiculata, a species described from Deception Island (Van de Vijver & Mataloni 2008), has larger valves with a relatively broad axial area and short, weakly deflected raphe fissures -bearing side, contrary to L. neglecta (Table 1). Moreover, L. quadriscrobiculata typically has four pit-like depressions present in the central area, a feature never observed in L. neglecta. Both L. australomutica and L. delicatula have larger valve dimensions, short distal raphe fissures and a coarser striation pattern (Table 1). The distal raphe fissures in L. neglecta are similar to those of the Antarctic L. nelidae Van de Vijver in Van de Vijver & Mataloni (2008: 458) but the latter has much larger and more linear-lanceolate valves with broader apices (Table 1). Luticola simplex Metzeltin, Lange-Bertalot & García-Rodríguez in Metzeltin et al. (2005: 116), described from Uruguay, is similar in valve outline but has more rhombic-lanceolate valves with a larger valve width (> 5 µm), a lower number of striae and a different raphe structure, with the proximal raphe endings deflected opposite to the pore contrary to L. neglecta (Table 1). Other similar taxa from around the world include Luticola imbricata (Bock) Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 134) and L. pseudoimbricata Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 193). Both taxa can be separated from L. neglecta by their proximal raphe endings that are turned opposite the isolated pore. Luticola imbricata also have a lower number of striae; L. pseudoimbricata possesses slit-like and not rounded isolated pore (Table 1). L. pitranenis Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 187), described from Macedonia, has larger rhombic valves, a lower stria density (Table 1), a different raphe structure with more hooked proximal raphe endings and striae composed of 4 5 larger areolae, compared to the 2 3 small and rounded areolae in L. neglecta. Both Luticola intermedia (Hustedt) Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 138) and L. frickei Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 114) have larger valves with proximal raphe endings deflected or hooked -bearing side (Table 1) and striae composed of more areolae (4 5 vs. 2 3). Another recently described taxon, L. minima Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 157) has a comparable valve dimensions and striation pattern to L. neglecta (Table 1), but again it can be separated by the proximal raphe endings that are deflected towards the side and not to the pore-bearing side. Finally, L. mutica has much longer proximal raphe endings, often hooked and even curved backwards, and a much lower stria density and larger valves, compared to L. neglecta (Table 1) to exclude conspecificity. 158 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

5 TABLE 1. Table of comparison between Luticola neglecta sp. nov. and morphologically similar taxa. Luticola valve outline valve apices valve length, µm valve width, µm axial area central area isolated pore striae in 10 µm proximal raphe endings neglecta lanceolate, elliptic-lanceolate to rhombic-lanceolate australomutica lanceolate, elliptic lanceolate to rhombic-lanceolate delicatula rhombic-lanceolate to elliptic-lanceolate rounded narrow, linear to linear-lanceolate broadly rounded to rostrate-capitate wide, almost linear bow-tie shaped, often asymmetrical wedge shaped rounded to transapically elongated rounded shortly hooked towards the pore short, deflected broadly rounded narrow, linear asymmetrical to elliptic slit-like slightly curved frickei linear-lanceolate to linear narrowly rounded narrow, linear rectangular to bow-tie rounded hooked opposite shaped, weakly the pore asymmetric imbricata linear-lanceolate to narrowly rounded (7) (34) (9.0) narrow, linear wide, bow-tie shaped rounded short, deflected intermedia lanceolate to rhombic-elliptic elliptic-lanceolate broadly rounded narrow, linear wide, wedge shaped, bow-tie shaped rounded deflected minima linear-lanceolate to linear rounded narrow, linear narrow, rectangular to elliptic rounded curved opposite to the pore mutica rhombic-lanceolate, elliptic-lanceolate, linear-elliptic nelidae lanceolate to linear-lanceolate rounded narrow, linear narrow, elliptic, with scattered round depressions broadly rounded wide, linear rectangular to slightly wedge shaped elliptic short, doubly curved opposite the pore rounded deflected pitranenis rhombic-lanceolate narrowly rounded narrow, linear asymmetrical small, elongated strongly hooked to the pseudoimbricata elliptic-lanceolate broadly rounded narrow, linear rectangular, wedge shaped to bow-tie shaped slit-like weakly curved pusilla linear-lanceolate to elliptic-lanceolate weakly protracted, narrowly rounded wide, lanceolate bow-tie shaped, asymmetrical rounded short, curved quadriscrobiculata rhombic to rhombic-ellitic simplex rhombic-elliptic to rhombic-lanceolate broadly to obtusely rounded broad, almost linear narrow, rectangular to weakly wedge shaped, with four pit-like depressions weakly transapically elongated obtusely rounded narrow, linear large, rectangular weakly elongated weakly deflected curved opposite to the pore distal raphe fissures to the short to absent short to the pore side hooked to the opposite the to the toward the pore to the pore short, hooked to the short, weakly deflected opposite the pore short, weakly deflected opposite the to the Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 159

6 Luticola bogaertsiana sp. nov. (Figs 21 34) TYPE: ANTARCTICA. South Shetland Islands: King George Island, Fildes Peninsula, Sample KGI12, leg. R. Zidarova, coll. date 30/01/2013, slide no. BR-4365 (holotype), slide PLP-254 (isotype University of Antwerp, Belgium), BRM-ZU9/70 (isotype BRM). Etymology: The species is named after our dear colleague and friend Ann Bogaerts (Botanic Garden Meise, Belgium). Valves linear with a single constriction in the middle, and broadly rounded, capitate apices. Valve length µm, width µm (constriction) and µm (widest part). Axial area narrow, linear, weakly widening towards the elliptical to bow-tie shaped central area. Central area bordered on both sides by a single row of areolae. One rounded isolated pore present in the central area. Raphe almost straight with proximal endings weakly deflected opposite the pore-bearing side and then hooked to the pore, and distal raphe fissures abruptly hooked to the. Striae radiate throughout, in 10 µm. Ecology and distribution: Luticola bogaertsiana is rarely observed and usually in very low numbers in soils and mosses, growing on rocks as well as on wet rocks at places with moderate to relatively high nutrient levels and elevated salinity. The largest populations were found in soils on coastal rocks and on wet rocks on King George Island where the species was recorded together with various Humidophila Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: in press) [formerly Diadesmis Kützing (1844: 109)] and Luticola taxa. Small populations were also observed on Livingston Island and Deception Island (Zidarova, Van de Vijver, pers. obs.). So far, no data exist from other localities in Antarctica. Kellogg & Kellogg (2002) list no records of Luticola binodis (or synonyms) with whom this species is often confused. LM observations: (Figs 21 32): The valves are linear with parallel margins showing a clear single constriction in the middle. The valve apices are broadly rounded and capitate. Valve dimensions (n=14): length µm, width µm (at the constriction) and max µm (widest part of the valve). The axial area is very narrow, linear and weakly widening towards the central area. The central area is expanded forming an almost elliptical (Fig. 30) to bow-tie shaped stauros (Figs 21, 26, 32), bordered on both sides by a single row of areolae. One rounded isolated pore is present in the central area, located almost halfway between the valve center and the valve margin and not associated with a stria. The raphe is almost straight with barely visible proximal raphe endings that are first weakly deflected away from the isolated pore and at the end hooked towards the pore-bearing valve side (Figs 21, 31). The distal fissures are hooked to the same direction (Figs 21, 26). The striae are radiate throughout the entire valve, in 10 µm. SEM observations: (Figs 33 34): Externally (Fig. 33), the striae are composed of 2 3(4) transapically elongated areolae becoming larger near the valve margins and smaller and more rounded towards the poles. The external proximal raphe endings are weakly but continuously deflected opposite to the isolated pore-bearing side, then abruptly shortly hooked towards the isolated pore. The distal fissures are abruptly shortly hooked to the same direction. The observations of the valve interior were only made on a single valve from the Deception Island population (Fig. 34). Internally, the central nodule is thickened. The central raphe endings are straight with the distal raphe endings terminating onto small helictoglossae. The areolae are covered by hymenes, forming a continuous strip along the striae. The internal isolated pore opening is covered by a c-shaped silica flap. Similar species: Luticola bogaertsiana was earlier reported as L. binodis by Van de Vijver et al. (2011). Levkov et al. (2013) already doubted that the maritime Antarctic species depicted in Van de Vijver et al. (2011, figs 46 48) would be conspecific with L. binodis s.s. Luticola binodis s.s., according to Levkov et al. (2013: 77) has a finer striation pattern as well as different raphe endings (Table 2). The proximal raphe endings in L. binodis are clearly bent -bearing side whereas in L. bogaertsiana they are abruptly shortly hooked to the. The distal raphe fissures in L. bogaertsiana differ also, being abruptly and shortly hooked, whereas the distal raphe fissures in L. binodis are elongated and strongly hooked. Of all known Antarctic Luticola taxa only L. adelae Van de Vijver & Zidarova in Van de Vijver et al. (2011: 148) and L. tomsui Kopalová in Kopalová et al. (2011: 56) can be confused with L. bogaertsiana. Luticola adelae has slightly smaller valve dimensions (Table 2). The axial area in L. adelae is clearly widening towards the central area whereas the axial area in L. bogaertsiana is narrow, linear and only weakly widening near the central area. The raphe endings in L. adelae are weakly deflected, whereas L. binodis has hooked raphe endings (Table 2). Luticola tomsui differs in having a broad, lanceolate axial area and completely different raphe structure with proximal raphe endings turned away from the pore-bearing side and short, weakly deflected distal raphe fissures (Table 2). Other Luticola taxa with biundulate margins that share similar features with L. bogaertsiana include L. binodeformis Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 76) and Luticola mollis Rumrich & Lange- Bertalot in Rumrich et al. (2000: 149). Luticola binodeformis is smaller, with a higher number of striae (Table 2). The proximal raphe endings are only weakly bent -bearing side and not abruptly hooked toward the isolated pore as in L. bogaertsiana. Luticola mollis has a broad axial area, widening towards the central area, as well as completely different raphe endings compared to L. bogaertsiana (Table 2). 160 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

7 TABLE 2. Table of comparison between L. bogaertsiana sp. nov. and morphologically similar taxa with biundulate margins. Luticola valve outline valve apices valve valve width, µm axial area central area isolated striae in proximal raphe length, µm pore 10 µm endings bogaertsiana linear capitate, (constriction), narrow, linear elliptic to bow-tie rounded shortly hooked to broadly (max.) shaped the pore rounded adelae linear capitate, (constriction), widening towards the rectangular, elliptical rounded weakly deflected broadly (max.) central area to bow-tie shaped rounded binodis broadly capitate to (constriction), narrow, linear elliptic to bow-tie rounded bent opposite the linear rostrate (max.) shaped pore binodeformis linear capitate to rostrate (constriction), (max.) narrow, linear bow-tie shaped elongated bent opposite the pore mollis linear capitate, broad, widening rectangular, round short, deflected broadly rounded towards the central asymmetrical area tomsui linear-elliptic capitate, broadly rounded broad, lanceolate rectangular to elliptical weakly elongated deflected opposite the pore distal raphe fissures shortly hooked to the very short, inconspicuous to the hooked to the short, straight short, weakly deflected Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 161

8 FIGURES Luticola bogaertsiana Zidarova, Levkov & Van de Vijver, sp. nov. Light (LM) and scanning electron microscope (SEM) micrographs: Figs 21, LM of 8 valves from the type population, King George Island, sample KGI12 (scale bars = 10 µm). Figs LM of 4 valves from a Deception Island population, sample D37 (scale bars = 10 µm). Fig. 33. SEM external view of a valve from the type population, King George Island, sample KGI12 (scale bar = 5 µm). Fig. 34. SEM internal view of a valve from a Deception Island population, sample D37 (scale bar = 5 µm). Luticola contii sp. nov. (Figs 35 49) Type: ANTARCTICA. South Shetland Islands: Deception Island, Sample D37, leg. R. Zidarova, coll. date 24/01/2013, slide no. BR (holotype), slide PLP-255 (isotype University of Antwerp, Belgium), BRM-ZU9/68 (isotype BRM). Etymology: The species is named after Gabriel (Tano) Conti, Base Commander at Decepción Base (Argentina) during the Antarctic season to thank him for his hospitality and readiness to help us in the field work during our (RZ) stay on Deception Island. Valves linear with triundulate margins and rostrate-subcapitate, rostrate or almost truncated apices. Valve length µm, width µm. Axial area narrow, linear, not or weakly widening towards the central area. Central area bowtie shaped to almost rectangular, bordered on both sides by 2 3 areolae. One rounded isolated pore present in the central area. Raphe straight, proximal raphe endings almost straight to weakly deflected away from the isolated pore. Distal raphe fissures very short, straight to weakly deflected away from the isolated pore. Striae radiate, in 10 µm. 162 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

9 Ecology and distribution: Due to confusion with Luticola nivalis the exact distribution of L. contii remains unknown and so far the species has been observed with certainty on Deception Island and King George Island (South Shetland Islands). The largest populations were found in soils and among almost dry mosses growing on coastal rocks, at places with moderate nutrient input and elevated salinity levels due to the proximity of the sea. Accompanying taxa included Pinnunavis gebhardii and several other Luticola species. FIGURES Luticola contii Zidarova, Levkov & Van de Vijver, sp. nov. Light (LM) and scanning electron microscope (SEM) micrographs: Figs 35, LM of 14 valves from the type population, Deception Island, sample D37 (scale bars = 10 µm). Fig. 49. SEM external view of a valve from the type population, Deception Island, sample D37 (scale bar = 5 µm). LM observations: (Figs 35 48): The valves are linear with almost parallel, triundulate margins. The margin undulations are moderately deep, rounded and almost equal in width. The valve apices in larger valves are rostratesubcapitate whereas in the smallest valves they are rostrate to almost truncated, always narrower than the valve middle. Valve dimensions (n=32): length µm, width µm. The axial area is narrow, linear (occasionally weakly Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 163

10 lanceolate, fig. 44), not or weakly widening towards the central area. The central area is expanded into a bow-tie shaped, sometimes almost rectangular (Figs 44, 46) stauros, usually bordered on both sides by a single row of 2 3 areolae. Occasionally 2 3 very short striae enclose the central area at one of the sides (Figs 41, 48). One rounded isolated pore is present in the central area, located almost halfway between the raphe and the margin showing a solitary position. The raphe is straight with slightly expanded proximal raphe endings, finishing almost straight to weakly deflected away from the isolated pore. The distal raphe fissures are very short and terminate straight to weakly deflected to the same side as the central raphe endings. The striae are radiate throughout the entire valve, in 10 µm. SEM observations: (Fig. 49): The striae are composed of 2 4 rounded areolae that become distinctly larger towards the valve margins. The areolae next to the axial area are very small and rounded. The areolae of the outer row are much larger and usually transapically elongated. One row of rounded areolae, not interrupted at the poles, is present on the valve mantle. The isolated pore opening is small, rounded to weakly transapically elongated. The proximal raphe endings are first weakly deflected away from the isolated pore but then hook shortly towards the isolated pore. Small pit-like depressions are present next to the raphe endings. The distal raphe fissures terminate near the last stria but never extend onto the mantle, first weakly deflected away from the isolated pore and then shortly hooked towards the isolated pore-bearing side. Similar species: Luticola contii has a unique raphe structure that is not observed in any other Luticola species with triundulate margins and this makes it easy to distinguish from the similar taxa, even in LM. However, in Antarctica the species has been reported for quite a long time as L. nivalis. Based on the studies of L. nivalis by Levkov et al. (2013: 175), the latter species has a denser striation pattern and different raphe endings (Table 3). The proximal raphe endings in L. nivalis are distinctly bent opposite the isolated pore and not towards the isolated pore, while the distal raphe fissures are hooked and much more prolonged compared to the distal raphe fissures in L. contii. Other Luticola taxa with a similar valve outline include Luticola cocquytiae Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 89), L. pseudonivalis (Bock) Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 199) and L. pulchra (McCall) Levkov, Metzeltin & Pavlov in Levkov et al. (2013: 202). They all have a finer striation pattern and proximal raphe endings that are bent or deflected opposite to the isolated pore-bearing side (Table 3). Other known Luticola taxa with triundulate margins are sufficiently different in valve outline and/or shape of the apices, striation and raphe structure to avoid confusion. In Antarctica, however, the species can be easily misidentified with L. olegsakharovii sp. nov. (see below). Detailed comparison between these two Antarctic taxa is given under L. olegsakharovii and in Table 3. Luticola olegsakharovii sp. nov. (Figs 50 64) Type: ANTARCTICA. South Shetland Islands: King George Island, Fildes Peninsula, Sample KGI81, leg. R. Zidarova, coll. date 13/02/2013, slide no. BR-4367 (holotype), slide PLP-256 (isotype University of Antwerp, Belgium), BRM-ZU9/71 (isotype BRM). Etymology: The species is named after Oleg Sakharov, Base Commander of Bellingshausen Russian Station on King George Island during Russian Antarctic overwintering Expedition to thank him for his hospitality and his professionalism in solving successfully the problems we had during our (RZ) field trips there. Valves linear to linear-elliptic with triundulate margins and subcapitate apices. Valve length µm, width µm. Axial area narrow, weakly lanceolate. Central area bow-tie shaped, bordered on both sides by a single row of 2 3 areolae. One rounded isolated pore present in the central area. Raphe straight with proximal and distal raphe endings shortly bent away from the isolated pore. Striae radiate, in 10 µm. Ecology and distribution: Luticola olegsakharovii was observed on several islands of the South Shetland Archipelago: Livingston Island, Deception Island and King George Island. The largest populations were found in moist soils with elevated nutrient input, close to skuas nests, usually accompanied by various Pinnularia and Humidophila (formerly Diadesmis) species and other Luticola taxa. It is possible that the species is more widespread in the Antarctic but its distribution is obscured due to confusion with Luticola nivalis in the past. LM observations: (Figs 50 62): The valves are linear to linear-elliptic with triundulate margins and subcapitate, broadly rounded apices. The undulations of the margins are rounded, with the median one slightly wider than the others. Valve dimensions (n=23): length µm, width µm. The axial area is narrow, weakly lanceolate and widens towards the central area. The central area is expanded into a bow-tie shaped stauros and is bordered on both sides by a single row of 2 3 areolae. Occasionally the central area is enclosed at the isolated pore-bearing side by very short striae (Figs 56, 57). One rounded isolated solitary pore is present in the central area, located almost halfway between the raphe and the margin. The raphe is straight with both proximal and distal raphe endings shortly bent away from the isolated pore (Fig. 50). The striae are radiate throughout, in 10 µm. 164 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

11 FIGURES Luticola olegsakharovii Zidarova, Levkov & Van de Vijver, sp. nov. Light (LM) and scanning electron microscope (SEM) micrographs: Figs 50, LM of 13 valves from the type population, King George Island, sample KGI81 (scale bars = 10 µm). Fig. 63. SEM external view of a valve from the type population, King George Island, sample KGI81 (scale bar = 5 µm). Fig. 64. SEM internal view of a valve from the type population, King George Island, sample KGI81 (scale bar = 5 µm). SEM observations: (Figs 63 64): Externally, the striae are composed of 2 4 transapically elongated areolae becoming larger towards the margins. Rarely some of the areolae of the inner row are almost rounded (Fig. 63). One row of rounded areolae, interrupted at the valve poles, is present on the valve mantle. The external isolated pore opening is transapically elongated. The external proximal raphe endings are slightly expanded and are shortly bent away from the isolated pore. The distal fissures are short and terminate just below the last striae, bent to the same direction as the proximal raphe endings. Internally (Fig. 64), the central nodule is thickened. The raphe is straight and terminates onto small helictoglossae at the poles. The internal isolated pore opening is rounded and covered by an almost circular silica flap. The areolae are covered by hymenes and form a continuous strip over the striae. Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 165

12 TABLE 3. Table of comparison between L. contii sp. nov. and L. olegsakharovii sp. nov. and morphologically similar taxa with triundulate margins. Luticola valve outline valve apices valve valve axial area central area isolated pore striae in proximal raphe length, µm width, µm 10 µm endings contii linear rostrate-subcapitate, rostrate narrow, linear, bow-tie shaped to rounded to shortly hooked to truncated rarely lanceolate rectangular weakly towards the pore elongated olegsakharovii linear to subcapitate, broadly narrow, weakly bow-tie shaped elongated shortly bent linear-elliptic rounded lanceolate cocquytiae linear subcapitate to rostrate narrow, linear bow-tie shaped round to weakly elongated bent opposite the pore nivalis linear subcapitate, rostrate to narrow, linear bow-tie shaped round bent opposite the truncated pore pseudonivalis linear rostrate narrow, linear elongated to bow-tie shaped round deflected opposite the pore pulchra linear capitate narrow, linear elongated to bow-tie shaped round bent opposite the pore distal raphe fissures shortly hooked to the shortly bent to the hooked to the hooked to the short, hooked to the 166 Phytotaxa 170 (3) 2014 Magnolia Press ZIDAROVA et al.

13 Similar species: Luticola olegsakharovii is most similar to L. contii (see above) but can be separated by the slightly larger valve width, the rounded, subcapitate apices and the completely different raphe structure with shortly bent opposite to the pore-bearing side distal and central raphe endings, contrary to L. contii where both the central and distal raphe endings are hooked toward the pore-bearing side (Table 3). Likewise L. contii, L. olegsakharovii has also been reported from Antarctica as L. nivalis. All similar taxa in the L. nivalis group can be easily differentiated from L. olegsakharovii based on the distal raphe fissures, which are strongly hooked and not shortly bent as in L. olegsakharovii. Moreover, the distal raphe endings in the similar taxa of L. nivalis group are hooked to the porebearing side and not to the side opposite the isolated pore (Table 3). Luticola nivalis has also a smaller valve width and a finer striation pattern (Table 3). Other similar taxa, such as L. pulchra, L. cocquytiae and L. pseudonivalis, apart of hooked distal raphe fissures, also have a finer striation pattern (Table 3). Luticola cocquytiae and L. pseudonivalis both have much smaller valve dimensions (Table 3). Luticola pseudonivalis and L. pulchra also have much smaller valve apices compared to L. olegsakharovii. Other Luticola taxa with triundulate margins are sufficiently different in valve outline and raphe structure to be confused with L. olegsakharovii. Acknowledgments The sampling and observations on King George Island and Deception Island were funded by Project ДМУ (Bulgarian Science Fund). Observations on Livingston Island were done within L Oréal-UNESCO For women in science Program (Bulgaria). The Olympus BX53 light microscope used at University of Sofia (SU) was bought under CEBDER Project. Sampling on the South Shetland Islands was made possible with the support of the Bulgarian Antarctic Institute (BAI). The staff of the Bellingshausen Russian Antarctic Station on King George Island and Decepcíon Argentinian Base on Deception Island are thanked for their help during our stay (RZ) there. Dr. Blagoy Uzunov (SU) is thanked for his help during the field work. Additional samples on Deception Island were acquired thanks the help of Dr. Gabriela Mataloni. Part of the research was funded within an EU Synthesys grant to BVDV to visit the National History Museum in London, UK. Dr. Alex Ball, the staff of the EMMA laboratory and Dr. Eileen J. Cox at the Natural History Museum are thanked for their help with the scanning electron microscopy. Mrs. Myriam de Haan is thanked for her technical assistance with the SEM at the Botanic Garden of Belgium. References Chown S.L. & Convey P. (2007) Spatial and temporal variability across life s hierarchies in the terrestrial Antarctic. Philosophical Transactions of The Royal Society, series B 362: Edlund, M.B., Soninkhishsig, N., Williams, R.M. & Stoermer, E.F. (2001) Biodiversity of Mongolia: Checklist of diatoms, including new distributional reports of 31 taxa. Nova Hedwigia 72: Ehrenberg, C.G. (1837) Über ein aus fossilen Infusorien bestehendes, 1832 zu Brod verbacknes Bergmehl von den Grenzen Lapplands in Schweden. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin, Ehrenberg, C.G. (1843) Mittheilungen über 2 neue asiatische Lager fossiler Infusorien-Erden aus dem russischen Trans-Kaukasien (Grusien) und Sibirien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin, Esposito, R.M.M., Spaulding, S.A., McKnight, D.M., Van de Vijver, B., Kopalová, K., Lubinski, D., Hall, B. & Whittaker, T. (2008) Inland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica. Botany 86: Frenguelli, J. (1945) El Platense y sus diatomeas, Las diatomeas del Platense. Revista del Museo de La Plata (Nueva Serie), Sección Paleontología 3: Grunow, A. (1877) New diatoms from Honduras, with notes by F. Kitton. Monthly Microscopical Journal, London 18: Hasle, G.R. & Fryxell, G.A. (1970) Diatoms: cleaning and mounting for light and electron microscopy. Transactions of the American Microscopical Society 89: Four new Luticola taxa Phytotaxa 170 (3) 2014 Magnolia Press 167

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