Plumatella fruticosa (Allman, 1844)

Satkauskienė, Ingrida, Wood, Timothy, Rutkauskaitė-Sucilienė, Jurgita, Mildazienė, Vida & Tuckutė, Simona, 2018, Freshwater bryozoans of Lithuania (Bryozoa), ZooKeys 774, pp. 53-75 : 53

Plumatella fruticosa (Allman, 1844) Fig. 7A, B

Material examined.

Colony from Rokai pond (Kaunas district) found in June 2016; floatoblasts from pond of Kaunas Botanical garden collected in July and August 2016.

Description.

The colony measured approximately 3 x 4 cm and had sparse, narrow and upright branches. Free statoblasts are long and narrow, exhibiting a length at least twice the width: 432-496 (459 ± 8) μm long and 187-220 (203 ± 4) μm (n=10) wide; L/W ratio 2.2; DfL 120-320 (197 ± 19) (n=10) μm; DfW 56-100 (75 ± 6) (n=6) μm; VfL 211-313 (266 ± 21) (n=4) μm and VfW 74-128 (108 ± 17) μm (n=3). Sessoblasts were not found during this study. According to Pajiedaitė (1933) the average size of the floatoblasts was 590 μm long and 230 μm wide.

Distribution in Europe.

Plumatella fruticosa is considered to be widespread, especially in northern portion of Europe ( Økland and Økland 2005). It is considered common in Poland ( Kaminski 1984).

Remarks on habitat and ecology on Lithuania.

Pajiedaitė collected colonies in Dubysa river ( Šiauliai district) and Satarečius pond (Utena district) ( Pajiedaitė 1933) At first glance we could state that P. fruticosa is common in Lithuania, since during this survey statoblasts were found in most water bodies. However, we found colonies only in Rokai pond with sandy-mud bottom and stones in the littoral (Table 1, Fig. 7). Thus, it is possible, that statoblasts are spread by waterfowl among various ponds and lakes, but these may not be the preferred environment for growing colonies ( Økland and Økland 2005).

Remarks.

The combined statoblast characteristics (large length/width ratio, strong asymmetry of floatoblast and sessoblast, narrow fenestra on dorsal floatoblast valve) distinguish P. fruticosa from all other plumatellid species ( Ricciardi and Reiswig 1994). Molecular results provided by Hartikainen ( Hartikainen et al. 2013) imply that P. fruticosa is not a plumatellid and provide evidence for polyphyly in Plumatella . However, the position of P. fruticosa remains unresolved ( Hartikainen et al. 2013).