Phialina pupula ( Müller, 1773 ) Foissner, 1983

Rajter, Ľubomír, Bourland, William & Vďačný, Peter, 2019, Morpho-molecular Characterization of the Litostomatean Predatory Ciliate Phialina pupula (Müller, 1773) Foissner, 1983 (Haptoria, Lacrymariidae), Acta Protozoologica 58 (1), pp. 53-68 : 55-57

Phialina pupula ( Müller, 1773) Foissner, 1983

Improved diagnosis (based on Boise population): In vivo size about 60–130 × 20–50 µm. Body shape highly variable depending on state of contraction, rang- ing from clavate in extended condition through fusi- form, pyriform, elliptical to almost globular in semi-contracted and contracted state. Macronucleus elliptical with a single micronucleus. Highly refractive dumb- bell-shaped inclusions scattered throughout cytoplasm and usually concentrated in anterior body part. Contractile vacuole subterminal in extended condition, terminal in contracted state. Extrusomes about 10 µm long, rod-shaped, attached to oral bulge and forming bundles in cytoplasm. On average 15 ciliary rows, each row anteriorly differentiated into a dorsal brush composed of one to four dikinetids.

Type locality: Müller (1773) did not specify the type locality. He mentioned only that he found the spe- cies in water and ice from dunghills during November and December.

Type material and voucher slides: No type material is available from Müller’s (1773) specimens. Three voucher slides containing protargol-impregnated specimens from the Boise population have been deposited at Department of Zoology, Comenius University in Bratislava .

Material studied: Specimens from lower micro- aerobic layers of the interstitial sandy sediments from the floodplain area of the Boise River near the Glen- wood Bridge, Boise, Idaho, U.S.A.

Etymology: Not given in the original description. The feminine Latin noun pupula is a diminutive form of pupa (doll, puppet or pupa of an insect), obviously referring to the doll- or pupa-like body shape of the cili- ate. The name is treated as a noun in the nominative singular standing in apposition to the generic name [Art. 11.9.1.2 of the International Commission on Zoological Nomenclature (1999)].

Description of Boise population: Size in vivo 60– 130 × 20–50 µm, usually about 85 × 30 µm, as calculat- ed from some in vivo measurements and morphometric data adding 15% preparation shrinkage; length:width ratio on average 2.2: 1 in vivo and 2.9:1 (n = 32) in pro- targol preparations ( Table 1). Body shape highly vari- able depending on state of contraction, ranging from clavate in extended condition through fusiform, pyri- form, elliptical to almost globular in semi-contracted and contracted state. Head barrel-shaped, about 8.5 × 6.0 µm in size after protargol impregnation, distinct from trunk but without neck-like region, sometimes re- tracted into trunk creating an impression of shoulders. Posterior body end tapered and tail-like in extended condition, narrowly to broadly rounded in semi-contracted and contracted state ( Figs 2A, E, F, 3A, C, E, F, H–M). Contraction occurs slowly.

Nuclear apparatus located in or slightly posterior to mid-body, usually slightly lateral of cell center. Macro- nucleus elliptical, on average 15 × 10 µm (n = 32) in size after protargol impregnation. Micronucleus adja- cent to macronucleus, usually attached to anterior pole of macronucleus, elliptical and about 2 µm long in vivo ( Table 1; Figs 2A, 3A, D, E, F). Contractile vacuole subterminal in extended specimens while terminal in semi-contracted and contracted cells, excretory pore(s) not recognizable in vivo or after protargol impregna- tion ( Figs 2A, F, 3A, F). Only one type of extrusomes, rod-shaped, about 10 × 0.5 µm in size in vivo, attached to oral bulge and in bundles scattered throughout cytoplasm, impregnate well with the protargol method used ( Figs 2A, C, 3C, F, G). Cortex very flexible, distinctly furrowed by ciliary rows, sometimes dotted by tips of cortical granules in SEM ( Fig. 4A–C). Cortical granules colorless, broadly elliptical to elliptical and about 0.8 × 0.4 µm in size in vivo, oriented perpendicularly to cell surface, rather irregularly and narrowly spaced forming seven or eight rows between adjacent ciliary rows, impregnate deeply with the protargol method used often making observations of the ciliary pattern difficult ( Figs 2D, 3A, F). Cytoplasm colorless, packed with few to many lipid droplets, some extrusome bun- dles, and many highly refractive inclusions. Individual inclusions dumbbell-shaped, about 2 µm long and usu- ally numerous in anterior body half, rendering the cell dark in appearance at low magnifications ( Figs 2A, B, 3A–C, E–M). Swims fast along helical trajectory by ro- tation about main body axis.

Somatic cilia about 8 µm long in vivo, arranged in an average of 15 rows, each row composed of about 22 monokinetids with some dikinetids (dividing basal bodies) irregularly interspersed. Somatic kineties ordinarily spaced, extend meridionally to slightly helically depending on state of contraction ( Table 1; Figs 2A, 4A, C). Dorsal brush at anterior end of all somatic ki- neties, very inconspicuous not only in vivo but also in protargol preparations and in SEM because composed of only two to five dikinetids (SEM measurements): first brush dikinetid bears a short, 1.5–2.0 µm-long, rod-like cilium followed by an ordinary cilium about 6.5 µm long; second dikinetid associated with a minute, 0.3 µm-long, stump-like cilium followed by an ordi- nary cilium; all following brush dikinetids with anterior basal body unciliated and posterior basal body bearing an ordinary cilium ( Table 1; Figs 2E, 4A, B).

Oral apparatus occupies apical end of head. Oral bulge contains tip of extrusomes, posteriorly delimited by circumoral kinety as usual in congeners. Circumoral kinety and its structure very difficult to recognize in protargol preparations, very likely composed of dikinet- ids. Head kineties helical and narrowly spaced, extend between circumoral kinety and dorsal brush, composed of densely arranged monokinetids bearing about 10 µm long cilia in vivo and almost completely covering head in SEM ( Figs 2A, E, 3A, 4A).