Plumatella repens (Linnaeus, 1758)

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

Plumatella repens (Linnaeus, 1758) Fig. 2

Material examined.

Ten floatoblasts collected from ponds of Kaunas Botanical garden, Raudondvaris pond in April 2015, and Skyplaičiai lake, collected in June 2015; colonies collected from Raudondvaris and Rokai pond in June 2015 and July 2016 respectively. Sessoblasts were not found.

Description.

Colonies were about 5-8 cm size. The transparent branches of colonies were attached to the substratum for almost whole of their length. Floatoblasts were identified by the broadly oval shape and the absence of tubercles on the statoblast annulus (Fig. 2). Floatoblasts were 315-341 (325 ± 3) µm long by 226-270 (252 ± 4) µm wide; L/W ratio was 1.3; VfL 144-245 (187 ± 14) µm; VfW 126-212 (168 ± 10) µm (n=10); DfL 135-258 (178 ± 14) µm; DfW126-212 (163 ± 9) µm (n=10). Fenestra of floatoblasts circular, covered with rounded tubercles that become less prominent towards the centre of fenestra. The annular nodules often described for this species have not yet been observed in Lithuanian material.

Distribution in Europe.

According to Økland and Økland (2005), Wood and Okamura (2005), P. repens is common in Britain, Ireland and Europe. Kaminski (1984) described P. repens as most common species in the studied lakes in Poland.

Remarks on habitat and ecology in Lithuania.

Plumatella repens has been the most commonly encountered species, with floatoblasts occurring in all surveyed sites, include lentic and stagnant habitats. Although colonies were found in only two ponds from listed sites, we have since become aware of colonies occurring in other lakes and ponds not listed here.

Pajiedaitė (1933) described P. repens as most common species in Lithuania, which can grow in various freshwater bodies. On the other hand, the exact locations of her collecting sites were not listed in her thesis. In addition, because of early difficulty in identifying this species, distribution reports prior to the mid-1980s are not necessarily reliable ( Wood and Okamura 2005).

Remarks.

Lacourt (1968) postulated close relationship between Plumatella repens and P. fungosa based on a "short oval statoblasts" and molecular studies confirmed a close relationship between these species ( Hirose et al. 2011). Plumatella repens can be confused with young colonies of P. fungosa ( Wood and Okamura 2005). In addition, statoblasts of P. repens are similar to those of its congeners P. nitens Wood, 1996, P. nodulosa Wood, 2001, P. orbisperma (Kellicott, 1882), P. recluse Smith, 1992, and P. rugosa Wood, Wood, Geimer & Massard, 1998 ( Massard and Geimer 2008a).