Pachytrocha zhytomirensis Boshko & Konstantynenko, 2009, n. sp.
Creators: name: Boshko, Elena G.
name: Konstantynenko, Lyudmila A.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Protozoa
Ciliophora
Oligohymenophorea
Peritrichida
Vaginicolidae
Pachytrocha
Pachytrocha zhytomirensis

description: Pachytrocha zhytomirensis n. sp.
(Fig. 1–11)
Deposition of types. Holotype slide with holotype organism (Heidenhain's hematoxylin) was deposited in the Schmalhausen Institute of Zoology (No. IP207). Paratype slides contain paratype organisms (Heidenhain's hematoxylin) were deposited in the same collection (No. IP208–IP210) and in the collections of the Natural History Museum, London, U.K. (No. 2009:6:12:1 – 2009:6:12:4).
Etymology: The specific name is of Latin derivation and reflects the geographical distribution of this species in the city of Zhytomir.
Diagnosis: Lorica colorless, elongate, tubular, tapering gradually toward each end, widest in basal half. Base of lorica rounded. The lorica two-layered, but exfoliation of endotheca from exotheca (the latter are terms proposed by Jankowski 1989 for inner and outer layers of lorica) well-marked only in region of base of lorica near scopula and stalk. Distal part of lorica curved at angle of approximately 20о with respect to longitudinal axis of body. Distal aperture moderately sloped, with even edges. Stalk consisting of three parts – exostyle, mesostyle and endostyle (Jankowski’s 1989 terms). External part of stalk (exostyle) relatively long and slender, provided with small basal disk at point of attachment to substrate. Mesostyle (stalk inside exotheca) wider than exostyle, longitudinally striated, and located in cone-shaped tubular passageway through base of lorica. Zooid attached to bottom of endotheca by low, wide disc (modified endostyle).
Lorica with single zooid. Cell body elongate, with prominent, annular ridge located slightly aboral to midpoint of body. Pellicle with distinct transverse striations. Peristomial disc large, prominent. Peristomial lip wide, extending well beyond maximal body width and unequal in thickness. Ventral side of peristomial lip near entrance to infundibulum extremely thick (twice as thick as dorsal side), with noticeable sulcus running transversely across it. When ciliate contracts, distal part of cell body bends toward concave side of lorica wall, and swollen edge of peristomial lip covers rest of cell body. Contractile vacuole located beneath peristomial lip near ventral wall of short infundibulum. Macronucleus elongate and ribbon-like with slightly recurved tips, oriented along longitudinal axis of body. Micronucleus located near aboral end of macronucleus. Adoral zone of cell body protruding as much as 37 µm from lorica when expanded. The telotroch is symmetric, elongated and cylindrical, without lamellar ring as in Cyclodonta Matthes, 1958.
Dimensions of body 90.0 – 98.5 x 10.0 – 17.0 µm (94.8 ± 2.3 x 13.9 ± 2.1; n = 18). Width of peristomial lip 17.5 – 23.7 µm (21.0 ± 2.1; n = 18). Dimensions of lorica 62.5–77.5 x 20.0–27.5 µm (71.8 ± 3.3 x 24.3 ± 3.0; n = 30). Width of aperture 12.5 – 17.5 µm (15.9 ±1.5; n = 30). External stalk up to 20.0 µm long (16.6 ±4.0; n = 30). Width of exostyle approximately 2.5 µm. Dimensions of mesostyle approximately 3.5 x 5.0 µm. Dimensions of telotroch fixed in formalin approximately 35.0 x 21.0 µm.
Differential diagnosis: The new species differs from Pachytrocha cothurnoides in shape of the lorica and by having an elongate zooid with a well-marked annular ridge. Pachytrocha cothurnoides has a less elongate lorica that is wider in relation to its width than in P. zhytomirensis n. sp. and its basal part is also more bulbous. Among all species from the closely-related genera Cothurnia and Pyxicola, the new species has several characters similar to Cothurnia angusta Kahl, 1933 (lorica shape, dimensions) and C. annulata Stokes, 1885 (partially lorica shape, cell body with annular ridge, the mesostyle located in tubular passageway). However, it differs from these species by having a peristomial lip that is unequal in thickness and when contracting, the upper part of the ciliate’s cell body bends toward the wall of the lorica.
description: Published as part of Boshko, Elena G. & Konstantynenko, Lyudmila A., 2009, A new species of Pachytrocha Kent, 1882 (Ciliophora, Peritrichia: Vaginicolidae), pp. 61-66 in Zootaxa 2198 on pages 62-65, DOI: 10.5281/zenodo.189564