Distribution of Didymosphenia, Gomphonema and Gomphosphenia diatoms (Bacillariophyta) in Turkish inland waters

Many diatom genera belong to the order Cymbellales. These include many widely distributed and common genera, e.g. Didymosphenia M.Schmidt, Gomphoneis Cleve, Gomphonema Ehrenberg, Gomphopleura Reichelt ex Tempère, Gomphosinica Kociolek, You, X.Wang & Q.Liuand, and Reimeria Kociolek & Stoermer. Of these, the following genera were selected for our research: Didymosphenia, Gomphonema, and Gomphosphenia. The genus Didymosphenia was described from Streymoy Island (the North Atlantic Faroe archipelago) in 1819 by Lyngbye. The genus is relatively small and currently includes 31 species recognized worldwide (Kociolek et al. 2019). Almost half of these species have been recently described (Metzeltin & Lange-Bertalot 2014). Gomphonema Ehrenberg is a large genus (over 500 taxa listed in Kociolek et al. 2019), distributed worldwide, e.g. in South America (Metzeltin & Lange-Bertalot 2007), North America (Kociolek & Kingston 1999), Asia (Lange-Bertalot & Genkal 1999; Karthick et al. 2011), Europe (Reichardt 1999; Levkov 2016), and Africa (Kociolek & Stoermer 1991; Spaulding & Kociolek 1998), and is found in a wide variety of freshwater habitats. This genus is also widespread in Turkish inland waters (Solak et al. 2016). The environmental ranges of some taxa are clearly defined and are therefore used in biomonitoring work (e.g. Lange-Bertalot et al. 2017; Bąk et al. 2012). Gomphosphenia Lange-Bertalot is represented by a very small group of known diatoms (16 taxa in Kociolek et al. 2019).

The area of Turkey is very heterogenous due to varied geological and climatic conditions. There are seven climate zones in Turkey, namely the Marmara region, the Aegean–Western Mediterranean region, the Black Sea region, Inner Anatolia, the Eastern Anatolian region, the South–Eastern Anatolian region, and the Eastern Mediterranean region. The average annual temperature amplitude ranges from 7.2°C in the Eastern Anatolian region to 18.7°C in the Eastern Mediterranean region. Annual precipitation ranges from 417.5 mm in the Eastern Anatolian region to 1175.8 mm in the Black Sea region. The diversity of climatic conditions is due to the mountain chains in the region of Black and Mediterranean seas and the perpendicular position of the mountain system in the Aegean Sea. Didymosphenia genimata was orginally known from lakes and streams at northern latitudes, from habitats with low levels of nutrients and low temperature. In recent decades, however, it has spread massively to lowland areas (Spaulding et al. 2005a, b; Ector & Blanco 2009). With regard to studies on inland waters in Turkey, only Didymosphenia genimata was reported from different parts of Anatolia (Solak et al. 2012). This taxon is considered a harmful invasive organism in lotic systems worldwide and can reach the level of nuisance in its native range (Ector & Blanco 2009). The largest genus Gomphonema is common in Turkish waters. A total of 75 taxa were recorded in Turkish freshwater diatom flora, with G. angustum, G. constrictum, G. olivaceum, G. pala and G. parvulum being among the most frequently reported species (Solak et al. 2012; Solak & Wojtal 2012). Until this publication, Gomphosphenia grovei was the only Gomphosphenia species reported from Turkish waters (Solak et al. 2012; Maraşlıoğlu & Gönülol 2019; Taşkın et al. 2019).

The current study provides an introduction to the variability of selected gomphonemoid genera in the phytobenthos of some springs, small streams, large rivers, shallow and deep lakes in the Meriç-Ergene (1), Marmara (2), Susurluk (3), Kuzey Ege (4), Gediz (5), Antalya (6), Akarçay (7), Sakarya (8), Konya (9), Kızılırmak (10), Yeşilırmak (11), Eastern Black Sea (12), and Euphrates–Tigris (13) catchments of the Anatolian Peninsula.

A total of 52 taxa were identified in our material collected from different catchments in Turkey (Table 1, Figure 1), of which 15 taxa were recorded for the first time in Turkey (*). The list of identified taxa is shown in Table 2.

Didymosphenia geminata (Lyngbye) M.Schmidt

Plate 1: 2, 3

Basionym. Echinella geminata Lyngbye

Ref. Kulikovskiy et al. 2016 (p. 200; pl. 134: 1–4), Metzeltin & Lange-Bertalot 2014 (p. 16; pl. 4: 1–4, 9: 1–7).

Dimensions: 65.5–110.9 μm long, 28.9–34.4 μm wide, 10–12 striae in 10 μm.

Distribution in our study: common in high-mountain lakes in the Black Sea region.

Distribution in Turkey: common.

Gomphonema acuminatum Ehrenberg

Plate 2: 4

Ref. Kulikovskiy et al. 2016 (p. 207; pl. 125: 1–7), Reichardt 1999 (p. 45; pl. 52: 1–14, 53: 1–17).

Dimensions: 46.3–60.7 μm long, 12.7–13.8 μm wide, from 10–12 (middle valve portion) to 13–16 (near apices) striae in 10 μm.

Distribution in our study: rare in Inner Anatolia.

Distribution in Turkey: common.

Gomphonema cf. aequale W.Gregory

Plate 2: 5, 6

Ref. Levkov et al. 2016 (p. 23; pl. 91: 1–42).

Dimensions: 19.8–24.0 μm long, 6.0–6.9 μm wide, 7–8 striae in 10 μm.

Distribution in our study: rare in Inner and Eastern Anatolia.

Distribution in Turkey: Gomphonema aequale is so far unknown from Turkey. However, the observed specimens differ from this species.

Remarks: Our specimens are more elliptical (not linear to linear-lanceolate) and have fewer striae than reported by Levkov et al. (2016). The occurance was recorded only in Konya (T86) and Euphrates–Tigris river basins (T120).

Plate 1

Plate 2

Gomphonema affine Kützing

Plate 2: 7

Ref. Reichardt 1999 (p. 13; pl. 7: 1–9, 8: 1–14, 9: 1–14), Levkov et al. 2016 (p. 24; pl. 41: 1–12).

Dimensions: 43.9–53.5 μm long, 10.4–11.3 μm wide, 7–11 striae in 10 μm.

Distribution in our study: rare in Inner and Thrace regions.

Distribution in Turkey: common.

Remarks: Some of the observed valves are similar to the Gomphonema species – G. insignaffine (Levkov 2016).

*Gomphonema affine var. rhombicum E.Reichardt

Plate 2: 8, 9

Ref. Reichardt 1999 (p. 15; pl. 10: 1–15).

Dimensions: 39.8–80.2 μm long, 9.6–12.9 μm wide, 9–11 striae in 10 μm.

Distribution in our study: rare in the Susurluk River in Western Anatolia.

Gomphonema angustatum (Kützing) Rabenhorst

Plate 2: 10, 11

Basionym. Sphenella angustata Kützing

Ref. Reichard 1999 (p. 23; pl. 24: 1–37), Levkov et al. 2016 (p. 26; pl. 51: 19–23).

Dimensions: 17.3–24.3 μm long, 4.4–5.8 μm wide, 12–15 striae in 10 μm.

Distribution in our study: rare in Altıntaş and Meram districts in Inner Anatolia.

Distribution in Turkey: common.

Remarks: Some specimens of G. angustatum were smaller than those described in papers by Reichard (1999) and Levkov et al. (2016).

*Gomphonema angusticephalum E.Reichardt & Lange-Bertalot

Plate 2: 12, 13

Ref. Kulikovskiy et al. 2016 (p. 208; pl. 125: 1–14), Reichardt 1999 (p. 49; pl. 60: 1–26).

Dimensions: 25.9–38.5 μm long, 4.9–6.5 μm wide, from 11–13 (middle valve portion) to 14–16 (near apices) striae in 10 μm.

Distribution in our study: found in Lake Uluabat in Western Anatolia (rare) and the Kesikköprü Reservoir in Inner Anatolia (common in Chara vulgaris).

Gomphonema angustius E.Reichardt

Plate 2: 14, 15

Ref. Reichardt 2009 (p. 163; Figs 9–30), Levkov et al. 2016 (p. 29; pl. 163: 32–51, 165: 1–32).

Dimensions: 14.0–16.9 μm long, 4.8–5.4 μm wide, 11–14 striae in 10 μm.

Distribution in our study: rare in the Simav and Gediz rivers and in the Domaniç district in Western Anatolia.

Distribution in Turkey: rare, observed only in the Aegean region – Kütahya flowing waters (Solak et al. 2016).

Gomphonema augur Ehrenberg

Plate 2: 16, 17

Ref. Levkov et al. 2016 (p. 32; pl. 35: 1–23).

Dimensions: 29.1–51.8 μm long, 11.4–12.9 μm wide, 10–13 striae in 10 μm.

Distribution in our study: rare in the Kaynarlı stream in the Thrace region, the Topuk stream in the Domaniç district and the Kelkit River in the Black Sea region, but common in the Porsuk River in Western Anatolia (Conductivity COND: 515 µS cm⁻², pH: 8.37 and dissolved oxygen DO: 10.2 mg l⁻¹).

Distribution in Turkey: common.

Gomphonema brebissonii Kützing

Plate 2: 18

Ref. Kulikovskiy et al. 2016 (p. 208; pl. 125: 18–20), Reichardt 1999 (p.46; pl. 56: 1–14, 57: 1–10), Levkov et al. 2016 (p. 37; pl. 5: 1–16).

Dimensions: 33.2 μm long, 7.1 μm wide, 13 striae in 10 μm.

Distribution in our study: rare, found only in the Meram district in Inner Anatolia.

Distribution in Turkey: rare in Lake Uluabat (Dalkiran et al. 2016) in Inner Anatolia.

*Gomphonema calcifugum Lange-Bertalot & E.Reichardt

Plate 2: 19, 20

Ref. Levkov et al. 2016 (p. 39; pl. 199: 29–53).

Dimensions: 12.3–19.9 μm long, 3.7–4.8 μm wide, 13–17 striae in 10 μm.

Distribution in our study: rare in the Değirmendere, Aygırlar, Safa, Topuk streams in Western Anatolia, also sparse in Lake Azap in North-Western Anatolia and common in some mountain streams in the Domaniç Kütahya (altitude: 1118–1204 m a.s.l., COND: 102–130 µS cm⁻², pH: 7.89–8.03 and DO: 10.8–11.1 mg l⁻¹).

Gomphonema capitatum Ehrenberg

Plate 2: 21

Ref. Kulikovskiy et al. 2016 (p. 208; pl. 126: 25–28), Levkov et al. 2016 (p. 40; pl. 32: 1–17).

Dimensions: 36.1–36.3 μm long, 10.4–11.7 μm wide, from 12 (middle valve portion) to 14 (near apices) striae in 10 μm.

Distribution in our study: rare in the Büyükköprü stream in Inner Anatolia.

Distribution in Turkey: rare in Lake Uluabat (Dalkiran et al. 2016) in Inner Anatolia, the Özlüce Reservoir (Şen et al. 2005) and the Kalecik Reservoir (Sönmez 2011) in Eastern Anatolia.

Gomphonema cf. clavatulum E.Reichardt

Plate 2: 22

Ref. Reichardt 1999 (p. 25; pl. 25: 1–23, 27–28).

Dimensions: 28.6–39.4 μm long, 5.7–7.1 μm wide, from 11 (middle valve portion) to 13 (near apices) striae in 10 μm.

Distribution in our study: rare, found only in the Kesikköprü Reservoir in Inner Anatolia.

Remarks: Our specimens of Gomphonema cf. clavatulum have more subrostrate apices than the type specimens (Reichardt 1999). The occurrence was noted only in the Kızılırmak river basins (T99). The exact identity of this taxon will be verified using scanning electron microscopy (SEM).

*Gomphonema elegantissimum E.Reichardt & Lange-Bertalot

Plate 2: 23, 24

Ref. Levkov et al. 2016 (p. 48; pl. 153: 28–55).

Dimensions: 22.2–29.6 μm long, 4.2–5.0 μm wide, from 11–12 (middle valve portion) to13–15 (near apices) striae in 10 μm.

Distribution in our study: rare in Lake Kovada in the Mediterranean region and in the Meram district in Inner Anatolia.

Remarks: the observed specimens probably belong to a group similar to G. elegantissimum. They have a different, more lanceolate outline, such as Fig. 23, which was identified as a Gomphonema species.

*Gomphonema exilissimum (Grunow) Lange-Bertalot & E.Reichardt

Plate 3: 25, 26

Basionym. Gomphonema parvulum var. exilissimum Grunow

Ref. Levkov et al. 2016 (p. 49; pl. 127: 1–33).

Dimensions: 15.0–26.3 μm long, 4.8–6.4 μm wide, from 13–14 (middle valve portion) to 15–16 (near apices) striae in 10 μm.

Distribution in our study: common, in the Keşiflik stream in the Thrace region, in the Kayaboğazı reservoir, the Kocasu and Ilıcaksu streams in Western Anatolia, the İvriz reservoir in Inner Anatolia, the Çakraz stream in Eastern Anatolia and the Altınsu stream in South–Eastern Anatolia. The species most likely occurs in other parts of the country.

Plate 3

Gomphonema cf. gracile Ehrenberg auct. Nonnull.

Plate 3: 27–29

Ref. Kulikovskiy et al. 2016 (p. 209; pl. 128: 1–3), Reichardt 2015 (p. 369; Figs 1–6).

Dimensions: 23.8–42.3 μm long, 4.9–6.9 μm wide, from 13–15 (middle valve portion) to 16–17 (near apices) striae in 10 μm.

Distribution in our study: rare in the Kesikköprü Reservoir in Inner Anatolia and Lake Tatos in the eastern Black Sea region.

Remarks: according to Reichardt (2015), the type specimens of G. gracile differ from those found in our sample. The most similar is G. graciledictum E. Reichardt, however, our specimens are smaller and more slender (less than 6.0 μm wide). They are also morphologically similar to G. hebridense (Fig. 29). They were found only in the Kızılırmak (T99) and Euphrates-Tigris river basins (T118). The exact identity of this taxon will be verified using scanning electron microscopy (SEM).

*Gomphonema graciledictum E.Reichardt

Plate 3: 30

Ref. Levkov et al. 2016 (p. 53; pl. 44: 1–25), Reichardt 2015 (p. 373; Figs 36–61).

Dimensions: 32.0–46.5 μm long, 6.7–7.5 μm wide, from 13 (middle valve portion) to 17 (near apices) striae in 10 μm.

Distribution in our study: rare in the Susurluk River and Lake Marmara in Western Anatolia.

Gomphonema insignaffine Reichardt

Ref. Reichardt 2009 (p. 164; Figs 31–42).

Dimensions: 41.1 μm long, 9.9 μm wide, 7 striae in 10 μm.

Distribution in our study: rare, noted only in the Gediz River in Western Anatolia.

Distribution in Turkey: rare in the Aegean region (Kütahya flowing waters – Solak et al. 2016, p. 574; Fig. 3: 52).

Gomphonema insigne W.Gregory

Ref. Levkov et al. 2016 (p. 60; pl. 50: 1–17).

Dimensions: 54.7–68.0 μm long, 11.1–12.7 μm wide, 7–8 striae in 10 μm.

Distribution in our study: rare in the Naşa and the Kokar stream in Western Anatolia.

Distribution in Turkey: frequent in Kütahya flowing waters (Solak et al. 2016, p. 574; Fig. 3: 50–51), Lake Uluabat (Dalkiran et al. 2016) in Western Anatolia, in the Darıören and Isparta streams (Çiçek et al. 2010) in the Mediterranean, in Karagöl (Açıkgöz & Baykal 2005), in Inner Anatolia and the Keban Reservoir (Pala 2007) in Eastern Anatolia.

Gomphonema italicum Kützing

Ref. Kulikovskiy et al. 2016 (p. 211; pl. 127: 9–14), Levkov et al. 2016 (p. 63; pl. 15: 1–16).

Dimensions: 20.0–57.7 μm long, 7.5–12.0 μm wide, 10–13 striae in 10 μm.

Distribution in our study: rare in Lake Uluabat, Lake Marmara, the İkizcetepe reservoir, the Simav, Orhaneli, Derbent, Porsuk and Felent streams in Western Anatolia, Lake Beyşehir in Inner Anatolia, the Kurtun River and abundant in the Karakuş stream in the Black Sea region.

Distribution in Turkey: common in Kütahya flowing waters (Solak et al. 2016, p. 574; Fig. 4: 58, 59) in Western Anatolia.

*Gomphonema italicum var. densistriatum Levkov, Mitic-Kopanja & E.Reichardt

Plate 3: 31

Ref. Levkov et al. 2016 (p. 64; pl. 16: 1–18).

Dimensions: 22.5 μm long, 11.2 μm wide, 18 striae in 10 μm.

Distribution in our study: rare, found in Lake İnekli in South Eastern Anatolia.

Gomphonema cf. latelanceolatum Levkov, Mitic-Kopanja & E.Reichardt

Plate 3: 32, 33

Ref. Levkov et al. 2016 (p. 71; pl. 73: 1–22).

Dimensions: 18.6–27.7 μm long, 5.9–9.0 μm wide, 13–15 striae in 10 μm.

Distribution in our study: rare in the Meriç River in the Thrace region and Lake Azap in Western Anatolia.

Remarks: our specimens differ in size (generally less than 25 μm long, more slender, less than 9.0 μm wide) with high density of striae (11–14 striae in 10 μm). They were found only in the Meriç-Ergene (T8) and Kuzey Ege river basins (T59). This taxon will be verified by SEM.

Gomphonema lateripunctatum E.Reichardt & Lange-Bertalot

Plate 3: 34–36

Ref. Levkov et al. 2016 (p. 73; pl. 143: 1–31).

Dimensions: 21.5–41.5 μm long, 3.6–6.6 μm wide, from 8–9 (middle valve portion) to 13–14 (near apices) striae in 10 μm.

Distribution in our study: rare in the Mutlu stream in Western Anatolia, Lake Beyşehir and the İbrala Reservoir in Inner Anatolia and the Elgazi stream in Black Sea region.

Distribution in Turkey: rare in Sakarya flowing waters (Morkoyunlu et al. 2017) in Western Anatolia and Lake Ladik (Maraşlıoğlu et al. 2007) in the Black Sea.

Gomphonema laticollum E.Reichardt

Ref. Kulikovskiy et al. 2016 (p. 212; pl. 126: 1–7), Levkov et al. 2016 (p. 74; pl. 22: 1–15, 23: 1–5, 24: 1–25, 25: 1–8, 26: 13–19).

Dimensions: 21.1–32.2 μm long, 8.7–9.5 μm wide, 11–13 striae in 10 μm.

Distribution in our study: rare in the Gördes Reservoir, the Milyas stream and the Porsuk River in Western Anatolia.

Distribution in Turkey: rare in Western Anatolia (Kütahya flowing waters – Solak et al. 2016, p. 574; Fig. 4: 60, 61).

Gomphonema linearoides Levkov

Plate 3: 37, 38

Ref. Levkov et al. 2016 (p. 75; pl. 195: 25–35).

Dimensions: 22.9 μm long, 4.7 μm wide, from 10 (middle valve portion) to 12 (near apices) striae in 10 μm.

Distribution in our study: rare, found only in the Yeşilırmak River in the Black Sea region.

*Gomphonema megalobrebissonii D.A.Chudaev, Kociolek & M.A.Golobova

Plate 3: 39

Ref. Van de Vijver & McBride 2003 (p. 443; Figs 1–14).

Dimensions: 49.4–70.0 μm long, 12.7–14.6 μm wide, 7–10 striae in 10 μm.

Distribution in our study: rare in Lake Dipsiz in Inner Anatolia.

Gomphonema micropus Kützing

Plate 3: 40, 41

Ref. Levkov et al. 2016 (p. 83; pl. 96: 21–40, 97: 1–37), Reichardt 1999 (p. 34; pl. 36: 1–14, 37: 1–29, 38: 1–15).

Dimensions: 17.3–29.9 μm long, 6.4–7.4 μm wide, from 11–12 (middle valve portion) to 13–15 (near apices) striae in 10 μm.

Distribution in our study: rare in the Kaynarlı stream in the Thrace region, the Değirmendere and Alaşehir streams in Western Anatolia, the Susuz and the Çakraz stream in Inner Anatolia.

Distribution in Turkey: Common.

*Gomphonema minusculum Cleve-Euler

Plate 3: 42, 43

Ref. Levkov et al. 2016 (p. 5; pl. 161: 1–25).

Dimensions: 21.0–40.0 μm long, 4.0–5.2 μm wide, from 10–12 (middle valve portion) to 13–14 (near apices) striae in 10 μm.

Distribution in our study: rare in the Kayaboğazı Reservoir, the Naşa District, the Felent stream in Western Anatolia.

Gomphonema minutum (C.Agardh) C.Agardh

Plate 3: 44, 45

Basionym. Licmophora minuta C.Agardh

Ref. Krammer & Lange-Bertalot 1986 (p. 370; pl. 81: 1–5), Levkov et al. 2016 (p.87: pl.171: 1–22, 172: 1–8).

Dimensions: 10.9–33.5 μm long, 4.0–6.1 μm wide, 10–15 striae in 10 μm.

Distribution in our study: rare in the Kuleli stream in the Thrace region, the Gölayağı stream, the Manyas Reservoir, the Mürüvetler, Simav, Kocaçay, Susurluk and Orhaneli streams, the Ovaköy district in Western Anatolia and the Çakmak Reservoir and the Mert River in the Black Sea region.

Distribution in Turkey: common.

*Gomphonema minutum f. syriacum Lange-Bertalot & E.Reichardt

Plate 3: 46, 47

Ref. Krammer & Lange-Bertalot 1986 (pl. 81; Figs 9–14)

Dimensions: 17.7–23.0 μm long, 5.1–6.2 μm wide, 11–12 striae in 10 μm.

Distribution in our study: Rare in the Gölbaşı Reservoir, the Nilüfer and Orhaneli streams in Western Anatolia.

Gomphonema olivaceoides Hustedt

Plate 3: 48

Ref. Reichardt 2009 (p. 168; Figs 60–65)

Dimensions: 23.5 μm long, 5.9 μm wide, 15 striae in 10 μm.

Distribution in our study: rare, found only in the Deliçay stream in Western Anatolia.

Distribution in Turkey: frequent in the Black Sea and Eastern Anatolia.

Gomphonema olivaceum (Hornemann) Brébisson

Plate 3: 49

Basionym. Ulva olivacea Hornemann

Ref. Levkov et al. 2016 (p. 91; pl. 184: 1–47).

Dimensions: 15.7–38.7 μm long, 4.6–7.1 μm wide, 10–15 striae in 10 μm.

Distribution in our study: rare in the Bent stream in the Thrace region, the Demirtaş Reservoir, the Ağıl stream in Western Anatolia, Lake Beyşehir in Inner Anatolia, the Tuzla stream in South Eastern Anatolia.

Distribution in Turkey: commonly reported from lentic and lotic waters in the country (Solak & Wojtal 2012, Solak et al. 2012).

Gomphonema parvulum (Kützing) Kützing

Plate 3: 50, 51

Basionym. Sphenella parvula Kützing

Ref. Kulikovskiy et al. 2016 (p. 213; pl. 128: 12–17), Levkov et al. 2016 (p. 98; pl. 102: 1–38, 103: 1–14).

Dimensions: 15.9–26.2 μm long, 4.5–7.1 μm wide, from 11–13 (middle valve portion) to 13–15 (near apices) striae in 10 μm.

Distribution in our study: rare in the Keşiflik stream in the Thrace region, the Altıntaş District in Western Anatolia, the Mamasın Reservoir in Inner Anatolia, the Çakmak Reservoir and the Terme stream in the Black Sea region and the Murat River in Eastern Anatolia.

Distribution in Turkey: common.

Gomphonema productum (Grunow) Lange-Bertalot & E.Reichardt

Plate 3: 52, 53

Basionym. Gomphonema angustatum var. productum Grunow

Ref. Reichardt 1999 (p. 31; pl. 32: 1–18), Levkov et al. 2016 (p. 106; pl. 96: 1–20).

Dimensions: 16.9–26.9 μm long, 6.1–6.9 μm wide, 11–13 striae in 10 μm.

Distribution in our study: rare, found in large numbers in the Eğir in Western Anatolia.

Distribution in Turkey: frequent in the Tersakan stream (Maraşlıoğlu et al. 2016) and some lakes (Soylu et al. 2005) in the Black Sea, in the Darıören and Isparta streams (Çiçek et al. 2010) in the Mediterranean and in Lake Hazar (Yıldırım et al. 2003), the Topçu pond (Akköz et al. 2004), the Özlüce Reservoir (Şen et al. 2005), the Keban Reservoir (Pala 2007), the Kalecik Reservoir (Sönmez 2011) in Eastern Anatolia.

Gomphonema cf. pseudaffine Levkov, Mitic-Kopanja & E.Reichardt

Plate 3: 54

Ref. Levkov et al. 2016 (p. 107; pl. 71: 1–25).

Dimensions: 40.0–73.9 μm long, 8.8–10.7 μm wide, from 9–11 (middle valve portion) to 13–17 (near apices) striae in 10 μm.

Distribution in our study: rare in Lake Beyşehir in Inner Anatolia and Lake Tatos in Black Sea region.

Remarks: our specimens have an outline that corresponds to G. pseudaffine, however, the striae are clearly more radiate in our valves. The occurrence was recorded only in Konya (T87) and the eastern Black Sea river basins (T118).

Gomphonema pseudoaugur Lange-Bertalot

Plate 3: 55

Ref. Krammer & Lange-Bertalot 1986 (p. 364; pl. 159: 1–4).

Dimensions: 28.7 μm long, 8.1 μm wide, from 11 (middle valve portion) and 14 (near apices) striae in 10 μm.

Distribution in our study: rare in Lake Uluabat in Western Anatolia.

Distribution in Turkey: rare in Lake Salt (Akbulut 2013) in Inner Anatolia and in Acarlar floodplain forest (Tunca et al. 2014) in Western Anatolia.

Gomphonema pumilum (Grunow) E.Reichardt & Lange-Bertalot

Basionym. Gomphonema intricatum var. pumilum Grunow

Ref. Kulikovskiy et al. 2016 (p. 214; pl. 125: 15–17), Levkov et al. 2016 (p. 110; pl. 151: 26–52).

Dimensions: 15.4–36.4 μm long, 3.1–6.5 μm wide, 10–14 striae in 10 μm.

Distribution in our study: frequent in the Ergene River in the Thrace region, the Ilıca District and the Gökçedere stream in the Marmarean region, the Gölbaşı Reservoir, the Kapıkaya, Orhaneli, Susurluk, Mürüvet, Simav, Değirmendere, Dursunbey, Aygırlar, Kocasu, Ilıca, Porsuk, Kokar streams, the Güneyköy and Domaniç districts in Western Anatolia, the Aksu stream in the Mediterranean region, the Kızılırmak River, Lake Beyşehir, the Meram District, Derebucak and Kesikköprü reservoirs in Inner Anatolia, the Çakmak Reservoir in the Black Sea region, the Yeşilırmak, Karasu and Murat rivers in Eastern Anatolia.

Distribution in Turkey: common in Akçay (Solak et al. 2005), Kütahya flowing waters (Solak et al. 2016, p. 575; Fig. 4: 62–64), the Küçük Menderes river basin (Solak et al. 2018a) in Western Anatolia, in the Çubuk River (Yıldız & Özkıran 1994) in Inner Anatolia and in the Black Sea (Taş & Yılmaz 2015).

Remarks: until now, this taxon has only been found in a few locations in Turkey. However, our results showed that G. pumilum occurs in many parts of the country.

Gomphonema pumilum var. rigidum E. Reichardt & Lange-Bertalot

Ref. Lange-Bertalot et al. 2017 (p. 319; pl. 99: 15–20).

Dimensions: 15.4–36.4 μm long, 3.1–6.5 μm wide, 10–14 striae in 10 μm.

Distribution in our study: rare, noted only in the Güneyköy District in Western Anatolia.

Distribution in Turkey: rare in Kütahya flowing waters (Solak et al. 2016, p. 575; Fig. 4: 65–67) in the Aegean region.

*Gomphonema reediae Levkov, Mitic-Kopanja & E.Reichardt

Plate 3: 56

Ref. Levkov et al. 2016 (p. 112; pl. 187: 1–31).

Dimensions: 28.3–29.2 μm long, 5.6–5.8 μm wide, from 13–14 (middle valve portion) to 15–16 (near apices) striae in 10 μm.

Distribution in our study: rare in the Gördes Reservoir in Western Anatolia and Lake Beyşehir in Inner Anatolia.

*Gomphonema sarcophagus W.Gregory

Plate 3: 57, 58

Ref. Reichardt 1999 (p. 30; pl. 30: 1–30, 31: 1–6), Levkov et al. 2016 (p. 116; pl. 94: 1–27).

Dimensions: 25.9–34.9 μm long, 6.7–7.8 μm wide, from 9–10 (middle valve portion) to 10–13 (near apices) striae in 10 μm.

Distribution in our study: rare in the Ömerli Reservoir in the Marmara region, the Büyükköprü stream and the Meram District in Inner Anatolia.

Remarks: The observed specimens have varying numbers of striae in 10 μm (see Figs 57 and 58).

Gomphonema stonei E. Reichardt

Ref. Reichardt 1999 (p. 16; pl. 13: 1–17).

Dimensions: 33.5–41.9 μm long, 8.7–9.6 μm wide, with 10–13 striae in 10 μm.

Distribution in our study: rare, found in the Ilıcaksu creek in Western Anatolia.

Distribution in Turkey: rare in the Aegean region (Kütahya flowing waters – Solak et al. 2016, p. 575; Fig. 4: 68, 69).

Gomphonema cf. subangustatum Lange-Bertalot, Cavacini, Tagliaventi & Alfinito

Plate 4: 59, 60

Ref. Lange-Bertalot et al. 2003 (p. 47; pl. 91: 1–15).

Dimensions: 15.8–23.3 μm long, 3.6–4.3 μm wide, from 14–16 (middle valve portion) to 14–18 (near apices) striae in 10 μm.

Distribution in our study: rare in the Meram District in Inner Anatolia.

Remarks: in our material, the specimens are very narrow, resulting in uncertainty in precise identification of individuals as G. subangustatum. The occurrence was recorded only in the Konya river basin (T86).

*Gomphonema subcapitatum (Grunow) E.Reichardt & Levkov

Plate 4: 61

Basionym. Gomphonema constrictum var. subcapitatum Grunow

Ref. Levkov et al. 2016 (p. 122; pl. 34: 1–29).

Dimensions: 29.3–31.9 μm long, 8.0–9.2 μm wide, 11–12 striae in 10 μm.

Distribution in our study: rare in Lake Büyük Akgöl in Western Anatolia, the Moçar stream in the Black Sea region.

Gomphonema subclavatum (Grunow) Grunow

Plate 4: 62, 63

Basionym. Gomphonema montanum var. subclavatulum Grunow

Ref. Levkov et al. 2016 (p. 123; pl. 64: 1–19).

Dimensions: 32.5–52.9 μm long, 6.4–9.6 μm wide, 9–12 striae in 10 μm.

Distribution in our study: rare in the Ilıcaksu creek in Western Anatolia, the Meram District in Inner Anatolia, the Kızılırmak River in the Black Sea region, Lake Tatos and Lake Uzungöl in the Black Sea region.

Distribution in Turkey: frequent in the Seyhan River (Kandemir-Çevik et al. 1994) in the Mediterranean, in Kazangöl (Aysel et al. 1998), Lake Stream (Aysel et al. 2001) in Western Anatolia, in the Keban Reservoir (Pala 2007) in Eastern Anatolia and in Lake Uzungöl (Şahin 1998) in the Black Sea.

Gomphonema supertergestinum E.Reichardt

Ref. Levkov et al. 2016 (p.127; pl. 165: 33–42).

Dimensions: 16.5–34.9 μm long, 6.1–8.6 μm wide, 11–12 striae in 10 μm.

Plate 4

Distribution in our study: rare in the Keşiflik stream in the Thrace region, the Susurluk and Porsuk rivers, the Kocasu stream and the Güneyköy District in Western Anatolia, the Çekerek River in the Black Sea region.

Distribution in Turkey: rare in Kütahya flowing waters (Solak et al. 2016, p. 575; Fig. 4: 70, 71) in the Aegean region.

Gomphonema tergestinum (Grunow) Fricke

Basionym. Gomphonema semiapertum var. tergestinum Grunow

Ref. Levkov et al. 2016 (p. 128; pl. 163: 1–31).

Dimensions: 10.3–26.6 μm long, 4.1–6.5 μm wide, 10–15 striae in 10 μm.

Distribution in our study: common in the Yavru District in Western Anatolia, the Kızılırmak and Fadlım rivers in Inner Anatolia, the Çakmak Reservoir, the Yeşilırmak and Çekerek rivers, the Çakrak and Tuzla streams in Eastern Anatolia.

Distribution in Turkey: frequent in Kütahya flowing waters (Solak et al. 2016, p. 575; Fig. 4: 72–74) in Aegean regions, in Uzungöl (Şahin 1998), the Cimil stream (Taş & Yılmaz 2015) in the Black Sea, in Hotamış (Yıldız et al. 1998), the Hirfanlı Reservoir (Baykal & Açıkgöz 2004), the Çamlıdere Reservoir (Baykal 2006) in Inner Anatolia.

Gomphonema vibrio Ehrenberg

Plate 4: 64, 65

Ref. Reichardt & Lange-Bertalot 1991 (p.522; pl. 2: 1–9).

Dimensions: 59.2–69.6 μm long, 8.9–10.1 μm wide, from 7–9 (middle valve portion) to 12–14 (near apices) striae in 10 μm.

Distribution in our study: rare in the Eğir District in Western Anatolia.

Distribution in Turkey: frequent in Akçay (Solak et al. 2005), Kütahya flowing waters (Solak et al. 2016) in Aegean and in Uzungöl (Şahin 1998) in the Black Sea regions.

Remarks: G. vibrio shows morphological variability, for example, the outline and the density of striae in the head pole (Figs 64 and 65), however, all specimens found were identified as belonging to this species and not to any variety as shown by Kowalska-Eliasz (2017).

Gomphonema sp. 1

Plate 4: 66

Dimensions: 26.8–34.1 μm long, 3.9–4.5 μm wide, from 10–12 (middle valve portion) to 12–14 (near apices) striae in 10 μm.

Distribution in our study: rare, found only in the Kesikköprü Reservoir in Inner Anatolia.

Remarks: the studied valves have a different central area compared to G. bavaricum (Reichardt & Lange-Bertalot 1991, p. 534, pl. 7, Figs 2–7), and striae are much denser near the apices. The central area of G. bavaricum sensu Reichardt and Lange-Bertalot is cross-rectangular to square, while the central area in our material is smaller and there are two striae there (as in G. dichotomum). In our specimens, the apical striae are much denser, as in G. pumilum. The difference between our specimens and G. pumilum are clear – in the axial area, G. pumilum has a much wider, lanceolate area.

Gomphonema sp. 2

Plate 4: 67

Dimensions: 45.1 μm long, 9.6 μm wide, 11 striae in the middle and 13 striae near apices in 10 μm.

Distribution in our study: rare, found only in Lake Uyuz in Inner Anatolia.

Remarks: the valves are similar to G. longiceps Ehrenberg (Reichardt 2015, p. 142, Figs 10–18), but they differ in the head pole outline and the width of striae. Another, more similar species is G. bukycanyonum Bukhtiyarova (Levkov et al. 2016, p. 38; pl. 80: 23–26).

Gomphonema sp. 3

Plate 4: 68, 69

Dimensions: 47.9–64.9 μm long, 12.1–14.2 μm wide, from 9–10 (middle valve portion) to 12–13 (near apices) striae in 10 μm.

Distribution in our study: rare, found only in the Karakuş stream in the Black Sea region.

Remarks: the most similar taxon is G. mexicanum Grunow (Reichardt 1999, p. 20; pl. 18: 1–15, 19: 1–13). This species was reported from Turkey as G. subclavatum var. mexicanum (Grunow) R.M. Patrick in Uzungöl (Şahin 1998) in the Black Sea and in the Tatar Reservoir (Varol et al. 2018) in Eastern Anatolia. The exact identity of this taxon will be verified using scanning electron microscopy (SEM).

Gomphonema sp. 4

Plate 4: 70, 71

Dimensions: 29.7–59.2 μm long, 9.4–11.3 μm wide, 8–11 striae in 10 μm.

Distribution in our study: rare in the Nilüfer Reservoir, the Kocaçay stream, the Porsuk River, the Güneyköy District in Western Anatolia.

Remarks: the most similar taxon is G. zellense E. Reichardt (1999, p. 11; pl. 5: 1–11). This species is known from Macedonia (Levkov et al. 2016). The observed morphological variability, including the size of valves and an outline, results in uncertainty in the precise identification of individuals.

*Gomphosphenia holmquistii (Foged) Lange-Bertalot

Plate 4: 72

Basionym. Gomphonema holmquistii Foged

Ref. Kulikovskiy et al. 2016 (p. 217; pl. 124: 59–61).

Dimensions: 17.9–22.8 μm long, 3.5–3.8 μm wide, 18–19 striae in 10 μm.

Distribution in our study: rare in the Güneyköy District in Western Anatolia and Lake Yay in Inner Anatolia.

In this study, a total of 52 taxa were found in the material collected from different basins in Turkey. Of the identified taxa, Gomphonema affine var. rhombicum, G. angusticephalum, G. angustivalva, G. calcifugum, G. elegantissimum, G. exilissimum, G. graciledictum, G. italicum var. densistriatum, G. linearoides, G. megalobrebissonii, G. minusculum, G. minutum f. syriacum, G. reediae, G. sarcophagus, G. subcapitatum, and Gomphosphenia holmquistii are the first records for the Turkish freshwater diatom flora. Several taxa were found in only one or a few basins. G. exillissimum, G. italicum, G. micropus, G. minutum, G. parvulum, G. pumilum and G. tergestinum were abundant in several different basins (Table 2). At individual sites, they occurred in populations of greatly varying size. Gomphonema augur occurred abundantly in the Porsuk River (T77: DO – 10.1 mg l⁻¹, pH – 8.4 and conductivity – 515.2 µS cm⁻²). This species is mainly found in alkaline, nutrient-rich lakes and other large water bodies (Lange-Bertalot et al. 2017). According to Lange-Bertalot et al. (2017), more data are needed to understand its autoecology. Gomphonema italicum was found in large numbers in the Karakuş Stream (T113: DO – 9.4 mg l⁻¹, pH – 7.8 and conductivity – 213.1 µS cm⁻²). The distribution of the species is not well established due to the fact that the species was previously identified as G. truncatum (Lange-Bertalot et al. 2017). Gomphonema productum was found abundant in a mountain stream in the Eğir District (T51: DO – 9.8 mg l⁻¹, pH – 7.6 and conductivity – 599.2 µS cm⁻²). This diatom is an indicator of good ecological quality and occurs in upland streams (Lange-Bertalot et al. 2017). Gomphosphenia holmquistii is poorly studied. The species prefers water with low temperatures, low conductivity and alkaline or near neutral pH (Noga et al. 2016).

Some identified taxa had different morphological dimensions compared to the type material. For example, Gomphonema angustatum was smaller than the type material in Reichardt (1999): 17.3–24.3 μm length and 4.4–5.8 μm width vs. 15.0–48.0 μm length and 5.2–6.6 μm width, respectively. G. capitatum was also smaller than specimens in Levkov et al. (2016): 36.1–36.3 μm vs. 44.0–52.0 μm length.

The recorded diversity of diatoms in Turkey is relatively low compared to other parts of the world, such as England (Hartley et al. 1996), the Netherlands (Cremer & Koolmees 2010) and Poland (Bąk et al. 2012), but the list continues to grow each year with new studies (e.g. centric diatoms – Solak et al. 2018b; nitzschioid diatoms – Solak et al. 2019). In many cases, rare taxa are not reported in the results of publications on diatoms in Turkish inland waters (Solak et al. 2012). However, records of these taxa are important for the assessment of biodiversity (Gillett et al. 2011).

Since 2013, the Turkish Government has been implementing the WFD program for freshwater biomonitoring in Turkey and has been trying to improve specific diatom indices for Turkish waters. However, a reliable index is based on correct taxonomic identification. Studies such as this will facilitate the identification of the most common, and perhaps even some rare, species found in Turkish waters.