Phialina pupula, measuring up to 125 um fully extended, from two different samples of the spring fed freshwater coastal pond at Ocean Dunes in the Atlantic Double Dunes reserve on eastern Long Island. The first is from my three week old old sample, which was a superficial skim of the bottom organic layer of the pond and which has become quite anaerobic and coincidentally shows Phialina for the first time since I collected it. The individual is from a new sample of the pond taken two days ago in which I took bottom sand from a depth of 5 or 6 cm and found Phialina in the first slide I examined. You can see the elliptical macronucleus in the newer sample which constitutes the final four photos. The macronucleus is largely obscured by food vacuoles in the very well fed individual from the older sample which constitutes most of the photos and all of the GIFs. Like their cousins the Lacrymaria, Phialina get tired and go into resting mode where they retract their head like oral apparatus and remain motionless for a while.
"Phialina pupula (Müller, 1773) Foissner, 1983 represents a free-living, predatory ciliate belonging to the subclass Haptoria Corliss, 1974 of the highly diverse class Litostomatea Small and Lynn, 1981. Müller (1773) described this species for the first time as a cone-shaped microorganism with an apical head-like structure. Later on, Bory de Saint-Vincent (1824) classified all ciliates with an apical head into the genera Phialina Bory de Saint-Vincent, 1824 and Lacrymaria Bory de Saint-Vincent, 1824. He distinguished the two genera by the localization of the cell mouth: Phialina has a lateral while Lacrymaria possesses a terminal cytostome. These generic characters were, however, revealed to be problematic and consequently most species were assigned to Lacrymaria (Ehrenberg 1838, Dujardin 1841, Claparède and Lachmann 1859, Fromentel 1874, Bütschli 1887–89, Penard 1922). Kahl (1930) noticed that all species with an apical head have only a terminal cell mouth. This showed the main diagnostic feature of the genus Phialina to be incorrect. Therefore, Kahl (1930) abandoned the genus name Phialina and used only the generic name Lacrymaria.
In spite of this, Phialina was resurrected and both genera were redefined as follows (Foissner 1983, Foissner et al. 1995): (i) Lacrymaria is highly contractile and has a conspicuously long, highly extensible, swan-like neck while (ii) Phialina is less contractile and does not have a distinct extensible neck but, instead, the head is attached directly to the trunk" (1).
Rajter et al write: "P. pupula is characterized by a size of about 60-130 × 20-50 µm, an elliptical macronucleus with a single micronucleus, highly refractive dumbbell-shaped inclusions scattered throughout the cytoplasm and concentrated in the anterior body half, a single subterminal/terminal contractile vacuole, about 10 µm long rod-shaped extrusomes, and an average of 15 ciliary rows. In phylogenetic analyses, the newly obtained sequences from P. pupula and Lacrymaria olor clustered within the family Lacrymariidae with full to moderate statistical support. Neither the genus Phialina nor the genus Lacrymaria was depicted monophyletic....." (1).
Morpho-molecular Characterization of the Litostomatean Predatory Ciliate Phialina pupula (Müller, 1773) Foissner, 1983 (Haptoria,Lacrymariidae).
Ľubomír RAJTER, William BOURLAND, Peter VĎAČNÝ. Acta Protozoologica · July 2019. https://www.researchgate.net/publication/334965520
Imaging in Nomarski DIC using Olympus BH2 under SPlan 40x objective plus variable phone cropping on Samsung Galaxy S9+.
