Amphora cf. proteus W.Gregory

Zidarova, Ralitsa, Ivanov, Plamen, Hristova, Ognyana, Dzhurova, Boryana & Hineva, Elitsa, 2022, The unexpected diversity in Amphora sensu lato (Bacillariophyta) at Sozopol Bay, the western Black Sea, Phytotaxa 544 (2), pp. 103-127 : 106

figs 2A–C & 8D:

Amphora cf. proteus W.Gregory

Morphometric data:— L: 40.7–52.5 µm; W: 8.5–9.8 µm; DS: 11–13; VS: 10–12 (n=5).

Notes:— These valves do not fit entirely A. proteus since they usually have a single elongated areola on the ventral side, and not two rows of areolae as in A. proteus ( Schoeman & Archibald 1986, Levkov 2009), although a very short second row could be present (figs 2B–C), as in some of the valves of A. proteus in Levkov (2009, Pl. 248: 6). Valves are also slightly smaller than those of the original A. proteus (length> 50 µm, width> 9 µm, Schoeman & Archibald 1986, Levkov 2009). However, the only valve we were able to find under SEM (fig. 8D) showed the presence of dimple-like depressions internally near the elongated central nodule, as in A. proteus ( Levkov 2009, Pl. 248: 6). Another similar taxon in both dimensions and striation pattern, A. proteoides f. varians Proshkina-Lavrenko , was described from the Black Sea ( Proshkina-Lavrenko 1963). Unfortunately, it is only known from her description and drawings (Proshkina-Lavrenko 1963, Pl. IX: 1–4), presenting insufficient details for species separation nowadays.