| Cantonati, Lange- | (Lange-Bert. & | G. stoermeri |
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| Species | Bert., Kociolek & G. tackei (Hustedt) E.Reichardt) A.A.Saber, sp. nov. Lange-Bert. Lange-Bert. | G. plenkoviciae Kociolek & G. tenuis Levkov & G.Udovič & Žutinić E.W.Thomas D.M. Williams |
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| Reference | This study Hustedt (1942) Lange-Bertalot (1995) Udovič et al. (2018) Thomas et al. (2009) Levkov & Williams |
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| | | (2011) |
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| Valve outline | linear-clavate to narrow, club- linear-clavate with | narrowly clavate linear-clavate, club-shaped, central |
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| clavate, with a shaped, and undulate margins | to linear in larger with small round region tumid |
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| broader central area slightly expanded in larger specimens specimens to granules can be |
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| in larger specimens transapically in and only clavate | clavate in smaller seen by SEM on |
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| the middle with smooth | specimens, with the valve face; large |
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| | margins in smaller | undulated margins specimens slightly |
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| | frustules | and an inflated tumid at the centre |
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| | | centre in longer |
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| | | valves but smaller |
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| | | specimens have |
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| | | convex margins |
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| Headpoles | rounded bluntly rounded narrowly rounded to | rounded and non- bluntly rounded obtusely rounded |
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| | nearly acute | protracted |
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| Footpoles | narrowly rounded slightly more narrowly rounded | acutely rounded narrowly rounded narrowly rounded |
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| narrowed than | |
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| headpoles | |
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| Valve length (μm) 8.0-17.5 | 10.0-26.0 12.0-50.0 | 12.0-45.0 10.0-21.0 22.0-42.0 |
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| Valve width (μm) 2.5-4.0 | c. 3 5.5-7.0 | 3.0-6.5 1.5-3.0 3.5-6.0 |
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| L/W ratio | 3.4-4.8 | – 2.2-7.1 | 4-6.9 6.7-6.8 6.3-6.8 |
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| Valve mantle 1 | with a single row of | – – | with two types of with a series of round clearly high with a |
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| rounded and slit-like | | areolae: round, occlusions single row of round |
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| areolae | | 2-4 rows, and in to slit-like areolae |
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| | | some specimens |
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| | | just single slit-like |
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| | | openings |
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| Axial area | rather lanceolate, narrow, linear lanceolate and widen rather wide, linear, narrow moderately narrow in |
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| narrow at the poles | near the centre | lanceolate to smaller specimens |
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| and widening towards | | narrow in small and much wider in |
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| the central area | | specimens larger valves |
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| Central area | ± rhombic, mostly with small, elongated almost round | widely elliptical rectangular with a broad |
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| externally | 2-4 shortened striae, elliptical to almost | unilateral fascia |
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| unilateral fascia might circular | |
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| be present | | |
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| Central nodule | slightly raised | – distinct and rounded | – small, mound-shapedslightly raised |
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| internally | | | |
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| Striae | radiate, with single slightly radiate radiate, becoming | weakly radiate, parallel to radiate, radiate to |
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| slit-like areolae, | parallel near the | becoming parallel with single slit- subparallel, with |
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| becoming almost | foot poles, with | near the poles, like areolae, 1-3 single round |
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| parallel round poroids | single areolae and | with single areolae, shortened striae areolae near the |
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| near the head- and | additional 1-2 | round-shaped at around the central central area and |
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| footpoles | isolated areolae | the mid-valve and area apices and narrow |
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| | present | slightly elongated slit-like areolae |
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| | | slits towards the at the valve |
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| | | poles, internally margin, internally |
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| | | areolae longer than areolae elongate |
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| | | externally and longer than |
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| | | externally |
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| Striae number | 23-27 28-30, at the middle13-18 | 19-22 28-35 14-16 |
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| (in 10 μm) | c. 25 | |
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| Raphe | straight, filiform straight, filiform straight, filiform | straight, filiform straight, filiform straight, filiform |
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| External and | straight and distinctly | – dilated into pores, | small, indistinct, slightly enlarged, slightly expanded |
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| internal | dilated into pores, | internally T-shaped | internally T-shaped internally with half and unilaterally |
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| proximal raphe internally T-shaped | | an anchor (not deflected, |
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| fissures | | | typically T-shaped) internally T-shaped |
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| | | in one direction only |
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| External and | with teardrop-shaped | – simple and unilaterallyshort, straight and slightly enlarged, slightly expanded |
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| internal | pores, internally | deflected, internally | slightly expanded internally with large to teardrop-like |
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| terminal raphe with relatively large | with small | into drop-like helictoglossae pores, internally |
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| fissures | helictoglossae | helictoglossae | pores, internally with small |
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| | | with distinct helictoglossae |
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| | | helictoglossae |
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| Habitats | epilithic epiphytic in ditches benthic | in sediments and epilithic, subaerial epilithic |
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| and wet meadows | benthic |
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