| Gomphosphenia minima sp. nov. | This study | Clavate to linear- lanceolate | 5.0–8.0 | 2.2–3.0 | 18–25 | Single elongated areola | Rather wide, lanceolate | Wide not distinctly separated from axial area | Straight | Unilaterally deflected as small hooks |
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| Gomphosphenia fontinalis Lange- Bertalot, Ector & Werum | Werum & Lange-Bertalot (2004) | Club-shaped | 5.0–8.0 | 1.5–2.3 | 25–32 | Single elongated areola | Lanceolate | Wide not distinctly separated from axial area | Slightly dilated and deflected | Unilaterally deflected as small hooks |
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| Gomphosphenia lingulatiformis (Lange-Bertalot & E. Reichardt) Lange- Bertalot | Lange-Bertalot (1995) | Linear-clavate with undulate margins, to clavate | 12.0– 50.0 | 5.5–7.0 | 13–18 | Single areola, with an additional 1–2 isolated areolae | Lanceolate, expanded towards the center | Wide | Simple, unilaterally deflected | T-shaped |
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| Gomphosphenia vallei Beauger, C.E.Wetzel, Allain & Ector | Beauger et al. (2022) | Lanceolate- clavate in larger specimens to clavate in smaller ones and elliptical in the smallest individuals | 4.2–13.1 | 1.5–2.5 | 23–29 | Uniseriate, single slit-like areolae, becoming almost round poroids near the poles | Linear and narrow | Absent to asymmetrical | Straight, filiform, with slightly dilated distal and proximal raphe endings | Deflected in one direction |
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| Gomphosphenia tackei (Hustedt) Lange-Bertalot | Coste & Ricard (1982), Krammer & Lange-Bertalot (1986), Simonsen (1987) | Linear-clavate | 10.0– 26.0 | 3.0–4.0 | 24–27 | One to three areolae | Narrow | Moderately wide, round | - | - |
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| Gomphosphenia plenkoviciae Gligora Udovič & Zutinić | Udovič et al. (2018) | Narrow linear | 12.0– 45.0 | 3.0–6.5 | 19–22 | Single areola | Rather wide, lanceolate, to narrow in small specimens | Wide elliptical | Short, straight, slightly expanded into drop-like pores | T-shaped |
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| Gomphosphenia patrickiana Cantonati, Lange- Bert alot, Kociolek & A.A. Saber | Saber et al. (2021) | Linear-clavate to clavate | 8.0–17.5 | 2.5–4.0 | 23–27 | Radiate, with single slit-like areolae | Lanceolate | Rhombic, mostly with 2-4 shortened striae, unilateral fascia might be present | With teardrop- shaped pores | T-shaped |
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| Gomphosphenia holmquistii (Foged) Lange-Bertalot | Noga et al. (2016) | Club-shaped | 33.0–36.0 | 5.0–6.0 | 18–20 | Single areola | Lanceolate | Wide, transversally expanded to the valve margin | Straight, filiform | T-shaped |
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| Gomphosphenia tenuis Levkov & D.M.Williams | Levkov & Williams (2011) | Distinctly club- shaped, narrowly linear | 22.0–42.0 | 3.5–6.2 | 14–16 | Single areola of variable shape | Moderately narrow in smaller specimens, wide in larger specimens | A broad unilateral fascia | Straight, short, expanded into tear-drop shaped pores | T-shaped |
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| Gomphosphenia grovei (M. Schmidt) Lange-Bertalot | Lange-Bertalot (1995) | Broadly clavate to linear-clavate | 1.05–70.0 | 8.0–11.0 | 10–12 | Two or more areolae | Wide | Slightly wider than axial area | - | - |
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| Gomphosphenia oahuensis (Hustedt) Lange-Bertalot | Moser et al. (1998) | Linear-lanceolate with capitate ends | Ca. 26.0 | 3.0–4.0 | Ca. 25 | - | Narrowly lanceolate | Indistinct | Straight | - |
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| Gomphosphenia ryukyuensis A. Tuji & Ohtsuka | Tuji (2016) | Clavate | 15.0–22.0 | 4.7–6.7 | 16–19 | Two areolae | Narrowly lanceolate | Transversally wide to fascia | Short and simple | T-shaped |
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| Gomphosphenia reicheltii (M.Schmidt) Lange- Bertalot | Ohtsuka et al. (2018) | Spathulate with cuneate headpole and narrowly rounded footpole | 10.3–32.0 | 3.5–6.6 | 20–28 | One to four areolae | Narrow | Small, round | - | - |
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