Plumatella emarginata (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 emarginata (Allman, 1844) Fig. 5

Material examined.

A few floatoblasts from Šventupė pond were collected in July 2016.

Description.

Floatoblasts elongated in shape, with a circular ventral fenestra and small dorsal fenestra, covered by tubercles. Floatoblasts were 357-489 (407 ± 18) µm long and 197-235 (216 ± 6) µm (n=6) wide, L/W ratio 1.9; DfL 97-125 (107 ± 9) µm; DfW 60-82 (68 ± 7) µm (n=3); VfL 101-184 (149 ± 9) µm and VfW 110-162 (133 ± 4) µm (n=6). The approximate size of statoblasts provided by Pajiedaite (1933) was 560 µm long and 260 µm wide.

Distribution in Europe.

Geimer and Massard (1986) defined the range of this species to include most of Europe. Økland and Økland (2005) considered P. emarginata to be a southern species, with limited distribution in Norway and Sweden.

Remarks on habitat and ecology in Lithuania.

Pajiedaitė (1933) described morphology of P. emarginata colonies, but her text is not clear about the location of collection sites. However, the statoblasts she found were recorded from Paštys Lake (55°42'36"N, 25°41'48"E), Satarečius pond and Dubysa River (Kaunas district, 55°12'12"N, 23°30'28"E).

In our survey only a few statoblasts were found in Šventupės pond (Table 1). Wood and Okamura (2005) noted that P. emarginata is particularly tolerant of rapidly-flowing water. The occurrence of floatoblasts in the Neries River (Kaunas district - not included in this study) is consistent with this observation, although colonies were not found. From our data P. emarginata would be considered uncommon in Lithuania, although this should be verified through further surveys.

Remarks.

The species is widely distributed throughout the Holarctic ( Wood and Okamura 2005), although some reports may have confused it with similar species, P. mukaii or P. reticulata ( Massard and Geimer 2008a).