Plumatella fungosa (Pallas, 1768)

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

Plumatella fungosa (Pallas, 1768) Fig. 4

Material examined.

A floatoblasts collected from Linksmakalnis pond (June 2015) and Maišia stream (April 2015). Colony from Aristava pond (locates in Kėdainiai district 55°17'07.1"N, 24°04'28.6"E and it is not included in general list of studied sites during this survey) was taken in June 2017 (Fig. 4).

Description.

The colony dark, spindle shaped, and large (15-17 cm), formed on stems of reeds ( Phragmites ). Examined floatoblasts exhibited characteristic tubercles on the floatoblast annulus (Fig. 4) and a ridge-like suture between the dorsal and ventral valves. Dorsal floatoblast tubercles were larger on the fenestra than on the annulus. The length of floatoblasts was 324-368 (339 ± 5) µm; width 220-290 (254 ± 8) µm (n=8), L/W ratio 1.3; DfL 130-160 (147 ± 4) µm (n=6); DfW 125-161 (144 ± 5) µm (n=6); VfL 214-250 (227 ± 4) µm and VfW 205-228 (214 ± 2) µm (n=6). However, dimensions of P. fungosa floatoblasts provided by Pajiedaitė (1933), were slightly larger: 470 μm × 290 μm. Pajiedaitė also recorded the variability in sessoblast dimensions from different localities: 790 μm × 470 μm in Nevėžis river (Kaunas district); 480 μm × 370 μm in Lake Aukštadvaris (Trakai district), and 580 μm × 420 μm in Snaigynas Lake (Lazdijai district) (Pajiedaite 1933). During current study sessoblasts were not found.

Distribution in Europe.

According to Wood and Okamura (2005) P. fungosa is widespread in Europe. It has been recorded from several places in southern Sweden and Finland; it is common in Denmark and has been reported from Iceland ( Økland and Økland 2005) and Poland ( Kaminski 1984).

Remarks on habitat and ecology in Lithuania.

During this survey, floatoblasts of P. fungosa were found in seven water bodies from 18 surveyed, with prevalence in stagnant water, with neutral to slightly alkaline pH 7.01-8.15 (Table 1). Pajiedaitė (1933) described the colonies in Kaunas Lagoon, Nevėžis River (Kaunas district) and Dubysa River ( Šiauliai district). She noted that P. fungosa often occurred in polluted water and described colonies, found in old port of Kaunas city, where water was polluted by oil of ships and trash. A similar observation has been made by other authors ( Bushnell 1966; Geimer and Massard 1986). Based on the available data, we consider P. fungosa to be prevalent in Lithuania.

Remarks.

Large bulky colonies of P. fungosa are easily recognizable freshwater bryozoan species in Europe ( Wood and Okamura 2004). Floatoblasts of P. fungosa are lateralyasymmetrical and distinctfrom the symmetrical floatoblasts of P. repens and P. rugosa . Molecular studies showed a close relationship between P. repens and P. fungosa ( Hirose et al. 2011).