First record of Epistylis plicatilis (Ciliophora: Peritrichia) attached to Pomacea canaliculata (Mollusca: Gastropoda) in Southern Brazil
Utz, Laura R. P.
Zootaxa
2007
2007-04-23
1454
1
49
57
Ehrenberg, 1831
Ehrenberg
1831
[151,579,1797,1823]
Oligohymenophorea
Epistylididae
Epistylis
Protozoa
Peritrichida
3
52
Ciliophora
species
plicatilis
Morphology of live specimens:Colonies were dichotomously branched with alternate branches terminating approximately at the same level ( Fig. 2). Neither the main stalk nor its branches were contractile. The main basal stalk was short, with a smooth surface, without protuberances or ridges. Primary branches were the longest in the colony, and similar in width to the main stalk with no difference found between collection sites ( Table 1). Colonies had up to 100 zooids, but usually consisted of 10–20 zooids that were similar in size. Zooids were elongate and ranged from 105.0 to 187.5 µm in length and from 25.0 to 52.5 µm in width ( Table 1, Fig. 2). When contracted, the zooid was transversely folded in the region near to the scopula ( Fig. 3). The peristomial lip was wider than the body and folded transversally in the fully extended zooid ( Fig. 4). It also presented a snout-like protuberance when the zooid was contracted ( Fig. 3). The epistomial disk was highly elevated, and was ~ ¾ as wide as the peristomial lip. A single “C-shaped” macronucleus was observed in the oral half of the cell, lying transversely below the peristomial lip ( Fig. 4). TABLE 2: Measurements of Protargol stained colonies of Epistylis plicatilisattached to Pomacea canaliculatafrom Lago Tarumã (T) and Eldorado do Sul (E) Southern Brazil. A total number of 10 zooids were measured for each character from each location. Character Locality Mean (µm) SD (µm) Mode CV (%) Range Total length of the body from epistomial disk to aboral end T 55.0 11.0 50.0 20.0 42.5 – 77.5 E 56.3 11.1 50.0 19.7 40.0 – 77.5 Width of the body at midpoint between oral and aboral ends T 42.0 3.5 40.0 8.5 37.5 – 50.0 E 42.8 5.0 42.5 11.5 37.5 – 55.0 Distance between trochal band and scopula T 9.4 2.4 7.5 25.5 7.5 – 12.5 E 10.5 2.7 12.5 26.1 7.5 – 12.5 Length of micronucleus T 8.9 1.3 10.0 15.0 7.5 – 10.0 E 9.3 1.2 10.0 13.1 7.5 – 10.0 Width of micronucleus T 7.9 0.9 7.5 12.0 7.5 – 10.0 E 8.2 1.2 7.5 14.8 7.5 – 10.0 Width of macronucleus at midpoint T 10.4 1.9 10.0 18.0 7.5 – 12.5 E 10.7 1.9 12.5 17.6 7.5 – 12.5 Width of basal stalk T 8.9 1.3 10.0 15.0 7.5 – 10.0 E 8.8 1.5 10.0 17.3 7.0 – 10.0 Number of zooids in the colony T 38.1 23.6 15.0 63.2 15.0 – 75.0 E 36.4 24.8 20.0 68.0 15.0 – 75.0 Morphology of stained specimens:Infraciliary and nuclear characteristics of E. plicatiliswere easily recognized in protargol stained colonies. A total of 22 somatic myonemes extended from the scopula to the epistomial disk of the zooid ( Fig. 5). In the trochal band, only one row of kinetosomes was present ( Fig. 6). A spherical micronucleus was located close to the C-shaped macronucleus ( Figs. 7 and 8). The oral infraciliature is typical of sessile peritrichs and presents an outer haplokinety and an inner polykinety (PK1) that describes approximately 1 ½ turns around the peristomial disk before entering the infundibulum ( Figs. 8and 9a). In addition to PK1, the infundibular polykineties PK2 and PK3 were also identified ( Figs. 8and 9b): PK1 consisted of three rows of kinetosomes equal in length. PK2 also presents three rows of kinetosomes equal in length that terminate at the adstomal curvature of PK1; only a narrow gap existed between PK1 and PK2. PK3 consists of three short rows of kinetosomes that lie in a right angle to PK2 ( Figs. 8and 9b). PK3 terminates adstomally, close to the adstomal end of PK2.