The cosmopolitan intertidal foraminifer Trochammina inflata (Montagu) is extensively used in both paleoenvironmental
reconstructions and ecological surveys of salt-marsh foraminifera, and therefore it needs correct identification. Images published
over years depict differences in test shape, umbilicus features, incurvation of sutures, and number of chambers in the last whorl.
For instance, Montagu (1808) described a 5-chambered specimen; revised description of Williamson (1858) as well as the
neotype description (Brönnimann & Whittaker, 1984) reported 6 chambers. Recent White Sea specimens — 7-chambered,
otherwise similar — inspired Mayer (1962) to propose a new subspecies ―Trochammina inflata (Montagu) subsp. n.?‖, but this
work was not finalised. Recently collected White Sea specimens of T. inflata perfectly fit to Mayer‘s description. It raises the
question whether it is possible to distinguish a new (sub)species based on the number of chambers or we are dealing with a
local morph of T. inflata.