Peridinium subinerme Pausen; Peters, 1928 (partim): 52 fig. 15; non P. subinerme Paulsen.
Peridinium parvicollum Balech, 1959 a: 87, Pl. IV (86-87), Pl. V (92-99).
After Balech, 1976: Length 53-77µm, width 55-87µm. Close to P. rosaceum, without its distinctive features. Longer than wide to wider than long. Sutures simple or in bands. Posterior triangle of 1' as long or longer than the anterior, with a noticeable convexity at the right of its posterior angle (in whole thecae not always easily seen, depending on the position of the specimen). Plate 3' large, generally somewhat higher than the sum of 4'' and 2a. Protoplasm rather dark. Sculpture a strong reticulation and rather dense pores.
Sometimes found in subantarctic waters where it may be confused with P. punctulatum.
This species is rarely reported. www.algaebase.org lists this species as 'p' indicating it has not been subject to any kind of verification.