Bacillariophyceae

Poniewozik, Małgorzata, Duangjan, Kritsana, Pekkoh, Jeeraporn & Wołowski, Konrad, 2020, Algae of bromeliad phytotelmata in the Queen Sirikit Botanical Garden, Chiang Mai, Thailand, Phytotaxa 432 (1), pp. 17-37 : 28

Bacillariophyceae

Apart from green algae, desmids and flagellates of different phyla, diatoms were also common and three genera were recorded as the most abundant: Eunotia , Gomphonema and Pinnularia ( Table 2). All three genera are considered to be typical or frequently stirred up in inorganically turbid shallow habitats - codon MP according to Padisák et al. (2009). This description refers to freshwater lakes, but it also indicates the environmental conditions these diatoms require. It means that they are sensitive to nutrient deficiency and for undisturbed growth high amount of nutrients must be available. Among them Eunotia bilunaris , E. soleirolii , Gomphonema graciledictum , G. naviculoides , G. hebridense and Pinnularia gibba were the species with the highest frequency. They were often found in many samples we investigated ( Table 2). Although the data about diatoms of phytotelmata are limited, previous studies have recorded a higher diversity and frequency of diatoms in phytotelmata in natural conditions than this study ( Lyra 1971, 1976, Gebühr et al. 2006). Eunotia soleirolii (Kütz.) Rabenh. ( Fig. 8 –(2-5)), typically found in slightly acidic or neutral habitats with low conductivity ( Van Damm et al. 1994), was frequently reported diatom in the botanical garden phytotelmata. Here we report three taxa of Gomphonema as new records for the Thai diatom flora, although it should be pointed out that we are aware of a specificity of bromeliad tank habitats: G. gracilledictum E.Reichardt ( Fig. 8 –(9-12)) recently described by Reichardt (2015), G. naviculoides W.Smith and G. hebridense W.Greg. According to Hofmann et al. (2013), the latter is reported from oligotrophic, neutral waters of lakes and rivers of mountain zones with low electrolyte content. We also recorded Discostella stelligera (Hust.) Houk & Klee ( Fig. 8–1 ), which is commonly found in waters of low conductivity ( Wunsam et al. 1995). It is surprising that this euplanktonic species ( Denys 1991) is found growing in the small microhabitat offered by bromeliad tanks, but it should be emphasized that requirements of all the mentioned diatoms concerning low electrolyte content and slightly acidic or neutral water were fulfilled in the bromeliad tanks we studied. During our studies a frequent component of algal assemblage was a very interesting species Rhopalodia gibba , a species that contains spheroid bodies inside the cell, which have been speculated as being able to provide nitrogen to their host diatom in the conditions of its deficiency (( Floener & Bothe 1980, Prechtl et al. 2004).

Figures

FIGURE 8. 1—Discostella stelligera (Hust.) Houk & Klee, (2–5)—Eunotia soleirolii (Klitz.) Rabenh., (6-8)—Gomphonema hebridense W.Gregory, (9–12)—Gomphonema graciledictum E.Reichardt. Scale bars = 10 μm.