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Assessment of Acculturation: Issues and Overview of Measures
Full text linkPublicly available acculturation measures are systematically reviewed based on three criteria: scale descriptors (name of the scale, authors, year, target group, age group, subscales, and number of items), psychometric properties (reliabilities) and conceptual and theoretical structure (acculturation conditions, acculturation orientations, acculturation outcomes, acculturation attitudes, acculturation behaviors, conceptual model and life domains). Majority of the reviewed acculturation measures are short, single-scale instruments that are directed to specific target groups. Additionally, they mainly assess behavioral acculturation outcomes than acculturation conditions and orientations. Regarding the psychometric properties; most measures have an adequate internal consistency; yet cross-cultural validity of the instruments have not been reported. Guidelines for choosing or developing acculturation instruments are provided in the chapter
Pinnularia gemella Van de Vijver
No full textPinnularia gemella Van de Vijver (in Van de Vijver et al. 2009: 432) (Figs 197–204) Valves linear with strictly parallel margins and broadly rounded, non-protracted apices. Valve dimensions (n=20): length 43–52 µm, width 7.3–8.8 µm. Axial area moderately broad, linear to linear-lanceolate, not, or only very slightly, widening towards the central area. Central area forming a rectangular, usually asymmetrical fascia. Raphe lateral with deflected proximal raphe endings terminating in weakly expanded pores. Distal raphe fissures bayonet-shaped. Striae almost parallel throughout the entire valve. Longitudinal lines absent. One single row of small spines visible on the primary side, 9–10 in 10 µm. Valves usually found in pairs, connected by linking spines, lying in juxtaposition. Habitat:— Pinnularia gemella was found in several larger lakes on the central plateau of Byers Peninsula. All lakes had a pH varying between 7.2 and 7.5 and a very low specific conductance level (<60 µS/ cm). The species seems to be absent from Hurd Peninsula. Observations:— Pinnularia gemella cannot be mistaken with any other species of Pinnularia due to the presence of the spines on the primary side. Only a few Pinnularia species have spines or form colonies in juxtaposition. Van de Vijver et al. (2004a, 2009) reviewed all colony- and/or spine-forming species of Pinnularia. Pinnularia subantarctica var. elongata has a similar valve outline but higher stria density and lacks the typical spines of P. gemella. Pinnularia subantarctica var. elongata ( Manguin in Bourrelly & Manguin) Van de Vijver & Le Cohu in Van de Vijver, Frenot & Beyens (Figs 206 –217) Valves linear to weakly linear-lanceolate with parallel to weakly convex valve margins and broadly rounded, subrostrate apices. Valve dimensions (n=25): length 27–59 µm, valve breadth 5.4–7.9 µm. Axial area narrow, near the centre weakly deltoid. Central area forming a broad almost rectangular, sometimes asymmetrical, fascia. Raphe slightly lateral with expanded and weakly deflected central pores. Terminal raphe fissures “?”- shaped. Striae slightly to moderately radiate in the middle, becoming convergent towards the apices, 14–15 in 10 µm. Longitudinal lines clearly present. Habitat:— Pinnularia subantarctica var. elongata was most abundant among wet mosses in areas close to the sea and in larger lakes, usually near the shoreline where the presence of animals was clearly visible. PH ranges from 6.9 to 8.4 with a specific conductance varying from 34 to almost 250 µS/cm. Observations:— Pinnularia subantarctica var. elongata is one of the smallest Pinnularia taxa presenting a longitudinal line running across its striae due to the partly internal covering of the striae, leaving only a small opening. It cannot be confused with other species. Pinnularia microstauron has a unique valve outline with more rostrate apices and clearly convex margins. Pinnularia subantarctica var. elongata ( Manguin in Bourrelly & Manguin) Van de Vijver & Le Cohu in Van de Vijver, Frenot & Beyens (Figs 206 –217) Valves linear to weakly linear-lanceolate with parallel to weakly convex valve margins and broadly rounded, subrostrate apices. Valve dimensions (n=25): length 27–59 µm, valve breadth 5.4–7.9 µm. Axial area narrow, near the centre weakly deltoid. Central area forming a broad almost rectangular, sometimes asymmetrical, fascia. Raphe slightly lateral with expanded and weakly deflected central pores. Terminal raphe fissures “?”- shaped. Striae slightly to moderately radiate in the middle, becoming convergent towards the apices, 14–15 in 10 µm. Longitudinal lines clearly present. Habitat:— Pinnularia subantarctica var. elongata was most abundant among wet mosses in areas close to the sea and in larger lakes, usually near the shoreline where the presence of animals was clearly visible. PH ranges from 6.9 to 8.4 with a specific conductance varying from 34 to almost 250 µS/cm. Observations:— Pinnularia subantarctica var. elongata is one of the smallest Pinnularia taxa presenting a longitudinal line running across its striae due to the partly internal covering of the striae, leaving only a small opening. It cannot be confused with other species. Pinnularia microstauron has a unique valve outline with more rostrate apices and clearly convex margins.Published as part of Zidarova, Ralitsa, Kopalová, Kateŕina & Vijver, Bart Van De, 2012, The genus Pinnularia (Bacillariophyta) excluding the section Distantes on Livingston Island (South Shetland Islands) with the description of twelve new taxa, pp. 11-37 in Phytotaxa 44 on pages 31-32, DOI: 10.11646/phytotaxa.44.1.2, http://zenodo.org/record/489499
Luticola ivetana Chattová & Lebouvier & Haan & Vijver 2017, sp. nov.
No full textLuticola 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.Published as part of Chattová, 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/113365
Brachysira sandrae Vijver 2014, sp. nov.
No full textBrachysira sandrae sp. nov. (Figs 2–26, 41–47) Type:— KERGUELEN. Val Travers, sample B13, leg. M. Lebouvier, coll. date 31/01/2005 (holotype, slide no. BR –4390; isotype, slide PLP –275, University of Antwerp, Belgium). LM (Figs 2–26):—Cells solitary. Valves narrowly lanceolate to rhombic lanceolate with convex margins and clearly protracted, rostrate, rounded apices. Smaller specimens with less protracted though still clearly rostrate apices. Valve dimensions (n=50): length 21–40 µm, width 5.4–7.1 µm.Axial area very narrow, linear. Central area small, symmetrical, rounded to elliptical due to shortened central striae. Raphe straight, filiform with simple, straight proximal endings. Distal raphe endings not visible in LM. Striae lineate, uniseriate, radiate throughout the entire valve, 29–31 in 10 µm, composed of 2–4 in LM clearly discernible areolae. SEM (Figs 42–47):–Valves entirely surrounded by an elevated ridge, clearly thickened near the valve apices (Figs 42, 43). Striae uniseriate composed of a series of 2–4 (near the apices usually 1) transapically elongated areolae. Areolae per stria showing an irregular length, the outer row usually being the longest, producing apically running hyaline undulations on the valve surface. Areolae foramina with small indentations (Figs 44, 45). Small papillae present on the interstriae, usually 5–7 per interstriae, but number rapidly declining towards the apices (Fig. 42). Mantle striae composed of one elongated bacilliform areola (Fig. 43). Near the apices, mantle striae closer together. Raphe branches bordered by an elevated ridge running from the central area to the apices, never fusing with the marginal ridge (Figs 44, 45). Raphe straight with inconspicuous, simple proximal endings (Fig. 44) and short, straight to weakly deflected distal endings (Fig. 45). T-shaped raphe endings only weakly and irregularly developed. Internally, central area symmetrical (Fig. 46) to asymmetrical (Fig. 47). Proximal raphe endings unilaterally bent (Fig. 46) to straight (Fig. 47). Distal raphe endings terminating on weakly raised helictoglossae. Due to erosion, internal areolar occlusions not observed. Ecology and Distribution:– Brachysira sandrae was found in several samples collected in some brooks and rivers in the Val Travers area (Kerguelen). The samples were quite species-rich and dominated by Achnanthidium sieminskae Witkowski, Kulikovskiy & Riaux-Gobin (2012: 65), A. modestiforme (Lange-Bert. in Lange-Bertalot & Krammer 1989: 107) Van de Vijver (in Van de Vijver et al. 2002: 17) and several Psammothidium taxa. The largest population was observed in sample B13, taken from the main hotspring at 70 m altitude with a water temperature of 62.4°C, a pH of 8 and a temperature of 18–20°C in the mosses floating on the surface. Etymology:—The species is named my dear friend, Mrs Sandra Scheerer (Jena, Germany) in recognition of her efforts in nature conservation and more specifically the protection of native European orchids.Published as part of Vijver, Bart Van De, 2014, Analysis of the type material of Navicula brachysira Brébisson with the description of Brachysira sandrae, a new raphid diatom (Bacillariophyceae) from Iles Kerguelen (TAAF, sub-Antarctica, southern Indian Ocean), pp. 139-147 in Phytotaxa 184 (3) on pages 141-144, DOI: 10.11646/phytotaxa.184.3.3, http://zenodo.org/record/514663
Achnanthidium lailae Van de Vijver in Zidarova
No full textAchnanthidium lailae Van de Vijver in Zidarova et al. (Zidarova et al. 2009) Figs 54-77 Morphological observations Light microscopy (Figs 54-74) Frustules in girdle view narrow, rectangular, bent around the transapical axis, apices weakly recurved (Figs 54-56).Valves linear to very slightly linear-lanceolate with almost parallel margins and nonprotracted, broadly rounded, never rostrate or capitate apices (Figs 57-74). Valve dimensions (n=30): length 10–14 µm, valve width 1.8–2.5 µm. Raphe valve (Figs 57-64) concave with a rather narrow, linear to linear-lanceolate axial area, widening towards the central area. Central area forming a typical rectangular fascia. Shortened marginal striae occasionally present in the central area. Raphe straight to weakly undulating with inconspicuous straight proximal raphe endings. Distal raphe fissures not discernible in LM. Striae weakly but still distinctly radiate near the valve center, becoming more radiate near the apices, 30–33 in 10 µm. Rapheless valve (Figs 65-74) slightly convex with moderately broad, clearly lanceolate axial area, widening near the valve centre. Central area elongated, rhombic lanceolate, never expanding into a fascia due to several longer marginal striae in the central area. Striae parallel to weakly radiate near the valve centre, more radiate near the apices, 28–30 in 10 µm. Scanning electron microscopy (Figs 75-77) Striae on the raphe valve composed of 2–3 small areolae (Fig. 77). Areolae close to the axial area and at the apices rounded. Marginal areolae sometimes narrow, transapically elongated and hence slit-like, sometimes fused with the second areola (Fig. 77). Striae of the rapheless valve composed of 2–3 rounded to slit-like external areola openings (Fig. 75). Mantle areolae slit-like. Internal areolae openings covered by hymenes (Figs 76, 77). When removed due to sample preparation, very narrow struts visible separating the areolae (Fig. 76). Raphe slightly undulating becoming narrower towards the apices (Fig. 77). Proximal raphe endings almost straight, inconspicuous. Distal raphe fissures weakly deflected, continuing slightly beyond the last striae, never onto the mantle (Fig. 77). Internally, proximal raphe endings shortly bent into opposite directions, terminating in a thickened central pore (Fig. 77). Distal raphe endings terminating on small helictoglossae. Ecology, distribution and associated diatom flora The type population was found in a large circumneutral lake (pH = 7.1) on Ulu Peninsula on James Ross Island (Zidarova et al. 2009). Since then, several other large populations were discovered in lakes on Clearwater Mesa, a volcanic tableland on James Ross Island next to Ulu Peninsula. All populations were observed in alkaline lakes (pH 8.1–8.7) with relatively high conductivity (1000–2000 µS/cm). The samples were dominated by Halamphora sp., Pinnularia australomicrostauron Zidarova et al. (Zidarova et al. 2012), Nitzschia cf. commutata Grunow in Cleve & Grunow, and Achnanthes coarctata (Bréb.) Grunow in Cleve & Grunow (Cleve & Grunow 1880) and Gomphonema sp. So far, no populations were found on other islands in the Maritime Antarctic Region (Kopalová & Van de Vijver 2013, Van de Vijver et al. unpubl. res.).Published as part of Vijver, Bart Van De & Kopalová, Kateřina, 2014, Four Achnanthidium species (Bacillariophyta) formerly identified as Achnanthidium minutissimum from the Antarctic Region, pp. 1-19 in European Journal of Taxonomy 79 on page 8, DOI: 10.5852/ejt.2014.79, http://zenodo.org/record/383505
Angusticopula cosmica Goeyers & Van de Vijver 2020, sp. nov.
No full textAngusticopula 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/397334
Hoogleraar Martina Vijver blij met landelijke erkenning voor haar 'Levend Lab' in Leiden
No full textDe watervlo is het lievelingsorganisme van eco-toxicoloog Martina Vijver. In haar werkkamer hangt een grote kleurplaat, ooit gevonden op een rommelmarkt. “Het is een beestje van twee millimeter, bijna altijd vrouwtjes die zichzelf klonen. En helemaal doorzichtig, dus je ziet het hartje kloppen en ook wat ze heeft gegeten. Ze is prachtig.”Environmental Biolog
Aulacoseira principissa Vijver 2012, sp.nov.
No full text<i>Aulacoseira principissa</i> sp.nov. (Figs 2–25) <p> <i>Frustula cylindrica, rectangularia in aspectu cinguli. Valvae circulares. Dimensiones valvarum: diameter discorum 4.0– 16.3</i> μ <i>m, limbus valvarum 4.2–6.8</i> μ <i>m. Discus planus, tectus areolis aequaliter dispersis sed saepe valvae tectae seriebus areolarum unis ac duabas in margino disci adsunt. Iunctura faciei valvae limbique leviter curvata. Striae limbi, 15–16 in 10</i> μ <i>m, parallelae. Areolae 18–20 in 10</i> μ <i>m. Collum paene angustum, sulcus indistinctus, pseudoseptum moderate latum praesens interius in limbo. Spinae marginales positae in iunctura faciei valvae limbique, bifurcatae, in omni costa pervalvari. Valvae separandae nonnullae adsunt, sine spinis. Rimoportula una observata in limbo, supra pseudoseptum.</i></p> <p>Frustules cylindrical, rectangular in girdle view. Valves circular, 4.0–16.3 µm in diameter. Mantle height 4.2– 6.8 µm. Discus flat with evenly arranged areolae but valves with only one to two rows of areolae near the discus margin likewise present. Valve face-mantle junction gently curved. Mantle areolae arranged in parallel rows, 15–16 in 10 µm. Areolae 18–20 in 10 µm. Collum rather narrow, sulcus indistinct, moderately thick Ringleiste present inside the mantle. Linking spines on each mantle costa, bifurcated. Separation valves completely spineless. One rimoportula present on the mantle, above the Ringleiste.</p> <p> <b>Type:</b> — KERGUELEN ISLANDS. Île Kerguelen: Val Studer, 04 February 1998, <i>B. Van de Vijver sample BW390</i>, slide no. BR-4263 (holotype BR), slide PLP-208 (isotype University of Antwerp), slide BRM-ZU8/ 33 (isotype BRM).</p> <p> <b>Ecology:—</b> The new <i>Aulacoseira</i> is a typical constituent of the aquatic diatom flora on the sub-Antarctic Iles Kerguelen. Almost all large populations (>20% of all counted valves in a sample) have been found in larger lakes, ponds and occasionally in small bog ponds. The pH of the sampled localities ranges between 6 (rarely 5) and 7 (rarely>7) indicating the preference of the species for slightly acid conditions. All populations were found in sites with low to very low specific conductance values (>80 µS cm -1). When measured, nutrient values were always very low. In mosses, the species was found only in low abundances and when observed, mosses were usually located close to the water edge of larger lakes and pools indicating a possible contamination from the aquatic habitat at high water levels. In purely terrestrial mosses (semi-wet to dry), the species was never observed. The communities with <i>A. principissa</i> were usually dominated by <i>Stauroforma exiguiformis</i> (Lange-Bertalot 1993: 45) Flower, Jones & Round (1996: 53) and <i>Psammothidium abundans</i> (Manguin in Bourrelly & Manguin 1954: 19) Bukhtiyarova & Round (1996: 22).</p> <p> <b>Distribution:</b> — <i>Aulacoseira principissa</i> is widely distributed in the sub-Antarctic Region (Fig. 1). Large populations have been found on most islands in the southern Indian Ocean (Van de Vijver <i>et al.</i> 2001, 2002, 2008) but also on South Georgia in the southern Atlantic Ocean (Van de Vijver & Beyens 1996). Only on Heard Island, the most southern of all Indian Ocean islands, only one small population was found (Van de Vijver et al. 2004). The species has however not (yet) been found on localities in the Maritime Antarctic Region such as the South Shetland Islands, nor on the Antarctic Continent (Kellogg & Kellogg 2002). This distribution pattern indicates that <i>A. principissa</i> is most likely a typical sub-Antarctic endemic. The species is most probably also present on Macquarie Island, a sub-Antarctic island in the southern Pacific Ocean (Krystyna Saunders, pers. comm.).</p> <p> <b>Etymology:</b> —The specific epithet <i>principissa</i> (latin for princess) refers to the delicate shape of the valve resembling a princess’ crown.</p> <p> <b>Observations:</b> —LM (Figs 2–14): Frustules in long chains of up to 40 cells (Figs 2–4). The valve diameter is 4.0–16.3 µm (mean 10.3 ± 3.5 µm; N = 25), the mantle height is 4.2–6.8 µm (mean 5.7 ± 0.8 µm; N = 25) and the ratio of mantle height to diameter varies between 0.4 and 1.2 (mean 0.74 ± 0.23; N =10). The mantle striae density is 15–16 in 10 µm (N = 10). SEM (Figs 15–25): <i>Mantle</i>: The collum, the lowest part of the mantle lacking areolae makes up only 10–15% of the mantle height (Figs 15, 17, 18). The entire collum is covered by narrow, raised ribs (Figs 17, 18). Between the striae, the entire mantle is covered by small, siliceous plaques (Fig 19). The pores in the girdle bands are very fine and typical of those found in other <i>Aulacoseira</i> species (Crawford & Likhoshway 1999) (Fig 16). The boundary between the areolated mantle and the collum, the sulcus, is almost indistinct (arrows in Fig 18). <i>Areolae</i>: The mantle striae consist of relatively small, round areolae, arranged in well separated rows, parallel to the pervalvar axis (Figs 17, 18). Areola density per stria varies between 18 and 20 in 10 µm (N = 10). The striae continue without interruption over the mantle/valve face margin onto the valve face (Figs 20, 21, 22). <i>Discus</i>: The discus is generally flat, never verrucose lacking papillae, with a gentle transition towards the mantle (Figs 20, 21, 22). The discus is usually entirely covered with rounded, evenly distributed areolae (Figs 5, 6, 7, 20, 22). However, some valves show large hyaline areas on the discus apparently lacking areolae although shallow traces of areolae still can be visible (Figs 9, 10, 11, 21). Internally, the areolae on both the mantle and the valve face are covered individually by irregular discrete vela, in the shape of a short funnel with the narrow ends pointing into the areolae (Crawford & Likhoshway 2002) (Figs 24, 25). <i>Separation valves</i>: a few separation valves were observed. These valves lack the typical separation spines which are commonly observed in <i>Aulacoseira</i> (Crawford & Likhoshway 1999). Separation valves show no trace of spines along the smooth valve face/ mantle rim, indicating spines were not eroded but are simply lacking (Fig. 22). The valve face is completely areolated (Fig. 22). <i>Ringleiste</i>: The Ringleiste is a rather narrow, bulge-like broadening (Figs 14, 17, 23, 24) located at the junction between the areolated mantle and the collum. The width of the Ringleiste is approximately 5–10 % of the valve diameter (N = 8). <i>Spines</i>: At the junction of the mantle and the valve face, a marginal ring of well developed linking spines can be seen, separated by one single areola (Figs 15, 17, 18, 20, 21). Spines are straight, run parallel to the pervalvar axis and clearly bifurcate at the end. Spines vary only rarely in shape, although some valves tend to have less bifurcating, irregularly shaped spines (Fig. 16). Spine length varies around 1.1 µm. Typical separation valves with characteristic long, pointed separation spines were never observed. <i>Rimoportula</i>: only one rimoportula was observed, located above the Ringleiste, replacing an areola in the normal stria (Figs 14, 24, see arrows). The only observation of a rimoportula made concerned an eroded valve making a description of its correct morphology impossible (Fig. 24). Since a large number of smaller and larger valve fragments (>50) have been observed without recording traces of a rimoportula, it is highly likely that rimoportulae are quite rare in this species.</p>Published as part of <i>Vijver, Bart Van De, 2012, Aulacoseira principissa sp. nov., a new ' centric' diatom species from the sub- Antarctic region, pp. 33-42 in Phytotaxa 52 (1)</i> on pages 35-38, DOI: 10.11646/phytotaxa.52.1.5, <a href="http://zenodo.org/record/10087326">http://zenodo.org/record/10087326</a>
Ulnaria longissima Van de Vijver & D. M. Williams 2022
No full text<i>Ulnaria longissima</i> (W.Sm.) Van de Vijver & D.M.Williams 2022: 2 <p> Basionym: <i>Synedra longissima</i> W.Sm. 1853: 72, pl. 12, fig. 95</p> <p> Synonyms: <i>Synedra ulna</i> var. <i>longissima</i> (W.Sm.) Grunow 1862: 395</p> <p> <i>Syndera ulna</i> var. <i>longissima</i> (W.Sm.) Brun 1880: 126</p> <p> <i>Synedra pulchella</i> var. <i>longissima</i> (W.Sm.) H.Schönf. 1907: 104</p> <p> <i>Ctenophora pulchella</i> var. <i>longissima</i> (W.Sm.) H.Schönf. 1907: 104, 248</p> <p> TYpe:— ENgLaND, “ POND iN BOtaNic GaRDeN, BeLfast, 1850, <i>Dr. Dickie</i> ” <b>BR</b> VI-46-B11, lectotype; BM 23758–60, BM 25314, BM 51036, isolectotypes.</p>Published as part of <i>Williams, David M. & Vijver, Bart Van De, 2023, The diatom genus Ctenophora: A discussion on its morphology, relationships, and some species, pp. 1-26 in Phytotaxa 632 (1)</i> on page 17, DOI: 10.11646/phytotaxa.632.1.1, <a href="http://zenodo.org/record/10435352">http://zenodo.org/record/10435352</a>
Luticola beyensii Van de Vijver, Ledeganck & Lebouvier
No full textLuticola 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 µm, width 6.0‒8.5 µm. 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 µm. 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 Chattová, 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/113365
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