Table 2 Morphological comparison of the brackish water Peridiniopsis species
P. minima a | P. minima b | P. salina c | P. cristata var. cristata d,e,f,g | P. cristata var. boliviensis h | P. cristata var. tubulifera h | |
|---|---|---|---|---|---|---|
Cell shape | oval to rhombic | pentagonal to rhombic | oval to spherical | pyriform | ovoid to subspherical | pyriform |
Length (μm) | 13.5–19.04 | 8–15 | 9.1–14.5 | (37) 43–61 | 32–40 | (27) 30–40 |
Width (μm) | 12.8–17.9 | 6–12 | 7.3–12.9 | 29–41 | 30–38 | 26–32 |
Theca ornamentation | smooth | smooth | smooth | verrucose to reticulate | finely reticulated | smooth |
Epitheca | broadly conical, equal to hypotheca | broadly conical, equal to hypotheca | broadly conical, equal to hypotheca | helmet-shaped, higher than hypotheca | broadly conical, equal to hypotheca | helmet-shaped, higher than hypotheca |
Plate tabulation | Po, X, 3′, 1a, 6″, 5c, 5 s, 5′′′, 2′′′′ | Po, X, 3′, 1a, 6″, 5c, 4 s?, 5′′′, 2′′′′ | Po, X, 4′, 1a, 6″, 6c, 5 s, 5′′′, 2′′′′ | Po, X?, 3′, 1a, 6″, 6c, 4-5 s?, 5′′′, 2′′′′ | Po, X?, 3′, 1a, 6″, ?c, ?s, 5′′′, 2′′′′ | Po, X, 3′, 1a, 6″, 6c, 5 s, 5′′′, 2′′′′ |
Intercalary plate | small, rhombic | small, rhombic | small, rhombic | large, hexagonal | large, hexagonal | large, hexagonal |
Intercalary plate location | dorsally between 2′, 3′, 3′′and 4′′ | dorsally between 2′, 3′, 3′′and 4′′ | laterally between 2′, 3′, 2′′and 3′′ | dorsally between 2′, 3′, 2′′, 3′′, 4′′ and 5′′ | dorsally between 2′, 3′, 2′′, 3′′, 4′′ and 5′′ | dorsally between 2′, 3′, 2′′, 3′′, 4′′ and 5′′ |
Apical spine | no | no | no | small dorsal membranous crest | absent or tiny dorsal membranous crest | no |
Antapical spine | no | no | no | membranous crest-shaped extension | membranous crest-shaped extension | no |
Eyespot | yes | yes | no | no | no | yes |
Endosymbiont | yes | yes | ? | ? | ? | ? |
Habitat (salinity range) | brackish waters (2-7.2) | fresh water rivers | brackish waters (2.2-16.2) | brackish waters (4.35-5.76; 3-77) | brackish waters (7.5) | brackish waters (5.7) |