A New Rotifer Species for Turkish Inland Waters

The zooplankton fauna of Lake Sapanca (Turkey) was studied during January 2009-May 2010 of monthly intervals. One Rotifera species, Ploesoma truncatum (Levander, 1894) is a new record for the Turkish inland waters fauna.

In last decades, many new record of Rotifera species were added to Turkish fauna (Altındağ et al. 2005;Kaya et al. 2008;Altındağ et al. 2009;Kaya et al. 2009;Kaya and Altındağ 2009;Bekleyen et al. 2011).Finally, Ustaoğlu et al. (2012) collected all studies up to 2012 in a paper.However, the studies on zooplankton fauna of Lake Sapanca is limited.Tokat (1975) found only 5 taxa, Ongan (1982) recorded 9 taxa and Rahe and Worthmann (1985) reported only 8 taxa of Rotifera species, in Lake Sapanca (Table 1).On the other hand, Okgerman (2008) conducted a detailed study and identified 35 taxa of Rotifera in the Lake (Table 1).Ploesoma was detected in the lake only in genus level (Table 1).Also, another member of aforementioned genus, which named Ploesoma hudsoni (Imhof 1891), was recorded in Lake Gala, when lake was still under oligotrophic conditions (DSI 1986;Segers et al. 1992).However, there is not any record about the Ploesoma truncatum (Levander 1894) in Turkish lakes.

Materials and Methods
In this study, Rotifera fauna has been studied in oligomesotrophic Turkish lake, Lake Sapanca between January 2009 and May 2010.Samples couldn't be taken in April 2010.It is located in the northeast of the Marmara region of Turkey (40°41'N to 40°44'N and 30°09'E to 30°20' E) (Figure 1).It is a tectonic lake with an area of 46.8 km 2 , and 250 km 2 basin.Its maximum depth is 55 m, whereas mean depth is 26 m.Lake Sapanca is a warm monomictic.In general, thermal stratification occur between late April and mid November.Its primary water sources are small rivers and groundwater (DSI, 1998).Lake Sapanca is a source of drinking water of Adapazarı and Kocaeli cities (Albay et al. 2003;Akçaalan et al. 2007).
The samples were collected by using a plankton net with 55 µm mesh size from two stations vertically during January 2009-May 2010 of monthly intervals.The samples were transferred to the polyethylene bottles and fixed with 4% formaldehyde solution.Rotifera species examination and counting (%N) were done using Nikon ECLIPSE TS100 inverted microscope.Identifications of Rotifera species were performed under Nikon mark YS100 model stereomicroscope.The diluted sodium hypochlorite was used to extract the trophi of species.To identify the species of Rotifera following references were reviewed: Kolisko (1974), Koste (1978), Pontin (1978), andHollowday (2002).Water temperature, pH, conductivity and Dissolved Oxygen were measured in situ by using YSI 650 MDS Multi-parameter instrument.

Results
P. truncatum is a loricate species (Figure 2).The head-plate of the specimen has small indentations dorsally, and it looks like almost straight.Also, this part seems a broad tongue if the caudal part is lifted.On the posterior of the dorsal antenna, crosswise ridges and borders are found.There are many longitudinal ridges on the surface of the shell, and they occurs a decisive triangle on the dorsal view of the specimen.The foot is partially annular in the upper reach.Its length of body, foot, and toe are 120-160; 70-80, and 25-32 µm, respectively (Hollowday 2002).
According to the data obtained over the entire study, P. truncatum was represented 1.83% of total zooplankton abundance, and 2.39% of total Rotifera abundance.High numbers of P. truncatum was determined in May 2010 (12.16% of total zooplankton abundance, and 12.37% of total Rotifera), whereas low abundance was established in cold months.Also, the assessment of the frequency of P. truncatum was done according to Koste and Terlutter (2001) (Table 2).

Discussion
Rotifera fauna will be given in another manuscript (Dorak et al. not publish yet).In the present study we present the first record of P. truncatum from Lake Sapanca (Turkey) (Figure 2).The taxonomical hierarchy of P. truncatum are given in below.This specimen is widely distributed Afrotropical, Australian, Nearctic, Neotropical and Palearctic regions around the world.P. truncatum is reported as thermophilic specimen (Koste 1978), and its embryonic development occurs at high temperatures, and this period continues for a long time (Edmondson 1960).P. truncatum was reported from various areas in the world including; Russia (Telesh 1995), Canada (Swadling et al. 2000), China (Lin et al. 2003;Zhaou et al. 2009), South America (Bonecker et al. 2005(Bonecker et al. , 2009)), Serbia (Cadjo et al. 2007), Greece (Doulka and Kehayias 2008;Kehayias et al. 2008), and North America (Barbiero and Warren 2011), except Turkey which is located in Palearctic region.Also, it has been a subject of several studies (e.g.Sudzuki et al. 1983;Molloy et al. 2014).
P. truncatum live in open waters of oligotrophic, ultraoligotrophic and mesotrophic lakes and ponds (Koste 1982).It was reported by Sládeček (1983) as an oligosaprobic specimen.Lake Sapanca is an oligomesotrophic lake with a clear water (Akçaalan et al. 2007).Some physicochemical characteristics of lake are given in Table 3. P. truncatum reached to high numbers in warm month (May 2010), when the water temperature was between 12.04-14.54°C in Lake Sapanca (Table 2 and Table 3).Many authors were reported that the abundance of P. truncatum positively correlated with water temperature (Swadling et al. 2000;Doulka and Kehayias 2008;Kehayias et al. 2008).
As a result, taxonomic studies are important to determine the biodiversity, and a new record for Turkish Rotifera fauna was added with this study.

Figure 1 .
Figure 1.Location of the Lake Sapanca and sampling stations.

Figure 2 .
Figure 2. General view of P. truncatum (A and B).The eggs of P. truncatum (C) and Trophi of the species (D).(Photographs were taken at x40 magnification).

Table 1 .
The Rotifera fauna of Lake Sapanca, according to the previous studies.

Table 2 .
Monthly presence of P. truncatum in Lake Sapanca.

Table 3 .
Some physicochemical characteristics of Lake Sapanca, and the preference of P. truncatum according to the literature.: The sampling date with a high abundance of P. truncatum in the present study. *