;"Achnanthidium barlasii sp. nov.";"Achnanthidium dumlupinarii sp. nov.";"Achnanthidium minutissimum";"Achnanthidium polonicum";"Achnanthidium ertzii";"Achnanthidium sieminskiae";"Achnanthidium tropicocatenatum"
"Valve length (μm)";12.0–21.5;15.0–26.0;8.8–17.4;11.4–21.5;18–22;11–18;10.3–23.9
"Valve width (μm)";2.0–3.0;2.5–3.5;2.2–4.1;2.6–4.0;2.2–2.6;2–3;2.7–3.5
"Valve outline";"linear with parallel margins and lanceolate";"linear–lanceolate to linear–rhombic, and clearly inflated in central portion";"linear-elliptic to linear-lanceolate";"narrow clearly lanceolate with convex margins";"linear-lanceolate with convex margins";linear-lanceolate;"linear-lanceolate, slightly inflated in the central portion"
"Valve apices";protracted;"subcapitate to capitate";"rostrate to subcapitate protracted or as a rectangular fascia";subcapitate;"clearly capitate";"protracted and capitate";"protracted, subcapitate to capitate"
"Striation pattern";"strongly radiate, throughout the valve and denser near the apices";"strongly radiate throughout the valve, denser towards the apices";"strongly radiate and denser near the apices";"radiate throughout the valve and more strongly radiate near the apices";-;"radiate throughout, strongly radiate near apices";"radiate throughout the valve, denser towards the apices"
"Raphe valve"
"Central area";"slightly rhombic with 1–2 spaced striae composed of 3, rounded rectangular areolae";"small bordered by 1–3 widely spaced stria both sides";"almost absent, slightly rounded or as a rectangular fascia (more rarely)";"rectangular fascia, in some valves with one shortened striae near the valve margins";"rounded, never forming a fascia due to presence of several shortened spaced central striae";"irregular, 1–2 shortened striae";"small rounded, bordered by one more widely spaced stria on one or both sides"
"Striae (in 10 μm)";27–30;27–28;"30 (up to 35 near the apices)";"33–34 (up to 35–38 near the apices)";28–30;30–32;"36–40 (up to 45 near the apices)"
"Number of areolae (per striae)";"3 (1–2 at the apices)";"4 at the central area, 3–4 at the apices";"3–4 (rarely 2)";3–5;2–3;3–4;3–6
"Rapheless valve"
"Central area";absent;"absent or slightly rhombic";"weakly elliptical and almost absent";"small, never forming a fascia with striae slightly more spaced than the striae located towards the apices";"almost non-existing, discernable due to several more widely spaced striae";"irregular, 1–2 shortened striae";"indistinct or narrow lanceolate"
"Striae (in 10 μm)";27–30;28–29;"35 (up to 40 near apices)";"28–30 (35–38 up to near the apices)";28–34;30–32;38–40
"Number of areolae (per striae)";"4 (2–3 at the apices)";"4–5 at the central area, 3–4 at the apices";3–5;3–5;2–3;3–5;3–6
Reference;"This study";"This study";"Novais (2015)";"Wojtal et al. (2011)";"Van de Vijver et al. (2011)";"Witkowski et al. (2012)";"Marquart et al. (2017)"