Vorticella veloxiiforme, Pereira & Brito & Eizirik & Utz, 2018

Pereira, Marcos W. O., Brito, Fabiano Carvalho, Eizirik, Eduardo & Utz, Laura R. P., 2018, Description of Two New Species of the Genus Vorticella (Ciliophora: Peritrichia) Epibionts on Pomacea canaliculata (Mollusca: Ampullariidae: Gastropoda) in Southern Brazil, Zootaxa 4508 (2), pp. 211-224 : 213-214

Vorticella veloxiiforme n.sp.

Diagnosis. Freshwater peritrich, with a cup-shaped zooid measuring 57 X 41 µm on average. Conspicuous silver line system on pellicle. Horizontal, J-shaped macronucleus occupying 2/3 of the cell volume. One contractile vacuole next to the peristomial lip. Stalk with a strongly contracting a helical spasmoneme, and green endoplasmic granules. Three infundibular polykineties, each comprised of three rows of kinetosomes: P2 and P3 terminate at the same level adstomally. P1 has one longer row of kinetosomes, terminating below the level of P2 and P3, which is hook-like shaped abstomally.

Type Locality. Patos Lagoon, Viamão (30° 19’70”S; 50°50’47”W), Rio Grande do Sul, Brazil.

Etymology. The specific epithet refers to the fast contraction mode of the trophont.

Deposition of slide. Type material: A slide with a protargol-stained colony (holotype) was deposited in the Protist Collection of the Museum of Sciences and Technology of the Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), under the number MCTP05. The paratype, a slide with a marked protargol-stained colony, was deposited in the Protist Collection of the Natural History Museum in London.

Morphology of live specimens. Zooids of V. veloxiiforme were inverted bell-shaped and measured on average 57.4 µm long and 41 µm wide ( Table 1). They also presented faint and closely spaced striae on the pellicle that, a thick peristomial lip, and a slightly elevated epistomial disk ( Figs. 1A and 2A ). A constriction below the peritomial lip was observed on the zooid body. A single contractile vacuole was found in the upper part of the zooid, close to the peristome ( Figs. 1A and 2A ). A J-shaped macronucleus was oriented along the oral-aboral axis and occupied approximately 2/3 of the volume of the cell body ( Figs. 1A , 2A and 2B ). The cytoplasm presented grayish and greenish food granules. The stalk measured on average 149.3µm in length ( Table 1). A spasmoneme was observed inside the stalk ( Figs. 1A and 2A ) and had several green endoplasmic granules throughout. Both the zooid and the stalk were very contractile.

Morphology of stained specimens. The infraciliature and macronucleus of V. veloxiiforme was easily revealed by silver staining ( Figs. 1C and D , 2D ). Somatic myonemes extended from the peristomial lip to the scopula ( Fig. 1E and 3C ). The oral infraciliature was typical of peritrich ciliates, with all infundibular polykinetids composed by three rows of kinetosomes each ( Figs. 1D and 2B ). Rows of P1 were different in length: the adstomal end of the row closer to P2 was longer than the other two. The end of middle row was longer than distal rows in P1 ( Figs. 1D and 2B ). All rows of P2 showed different lengths abstomally, but all terminated at the same level adstomally ( Figs. 1D and 2B ). P3 consisted of three rows of kinetosomes forming a hook-like projection at the abstomal end ( Figs. 1D and 2B ). Adstomally, P3 terminated at the same level of P1 and P2 ( Figs. 1D and 2B ). The silver nitrate technique, and the scanning electron microscopy revealed a horizontal striation pattern and the presence of pellicular pores regularly spaced on the zooid ( Figs.3A and B ). On average, 62 horizontal sileverlines were present between the peristome and the trochal band, and 20 were counted between the trochal band and scopula ( Table 2; Fig. 3C ).

Figures

FIGURE 1. Uorticella veloxiiforme live and protargol-stained specimens: A. Live zooids showing the contractile vacuole (CV), a J-shaped macronucleus and a spasmoneme inside the basal stalk (SM) (Bar 10 µm). B. Live zooid showing the position of the J-shaped macronucleus (MAC) (Bar 10 µm). C. Protargol-stained zooid showing the J-shaped macronucleus (MAC) (Bar 10 µm). D. Detail of a protargol-stained zooid showing the oral polykinetids (P1, P2, P3) inside the infundibulum (Bar 10 µm). E. Protargol-stained zooid showing the somatic myonemes (arrow) (Bar 10 µm).

FIGURE 2. Schematic drawings of Uorticella veloxiiforme n. sp. and Uorticela ampullaria sp.n. in vivo and from protargolstained specimens: A. Live zooid of U. veloxiiforme showing the contractile vacuole (CV) and a J-shaped macronucleus (MAC) (Bar 15 µm). B. Protargol-stained zooid of U. veloxiiforme showing the oral poliknetids inside the infundibular region (P1, P2, P3) (Bar 10 µm). C. Live zooid of U. ampullaria showing the position of the two contractile vacuoles (CV) and a Cshaped macronucleus (MAC) (Bar 15 µm). D. Protargol-stained zooid of U. ampullaria showing the oral polykinetids inside the infundibulum (P1, P2, P3) (Bar 10 µm).

FIGURE 3. Uorticella veloxiiforme n. sp. silver nitrate-stained species and SEM photomicrographs: A. Picture showing a zooid with horizontal striation and the trochal band (arrow) (Bar 10 µm). B. SEM micrograph of the zooid showing pellicular pores (arrow) (Bar 2 µm). C. Silver nitrate-stained zooid showing the silver lines on the pellicle (arrowheads) (Bar 20 µm).