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Труды ИБВВ РАН, вып. 76 (79), 2016
УДК 582.26: 581.4+582.261/296
TO MORPHOLOGY AND TAXONOMY OF TABELLARIA FLOCCULOSA
(BACILLARIOPHYTA)
S. I. Genkal1*, T. A. Chekryzheva2
'I. D. Papanin Institute for Biology of Inland Waters RAS Russia, '52742, Yaroslavl reg., Nekouz distr., Borok, e-mail: genkal@ibiw.yaroslavl.ru 2Institute of Water Problems of the North KarRC RAS Russia, '85003, Republic of Karelia, Petrozavodsk, Alexander Nevskiy ave., 50, e-mail: tchekryzhevas@mail.ru
This study of T. flocculosa/T. fenestrata complex in rivers and lakes of Karelia (Russia) has revealed a wide morphological variability of quantitative (valve length, central and terminal inflation widths, number of striae in 10 |im, number of rimoportulae per valve) and qualitative (shape of the valve and pseudoraphe, rimoportula arrangement, presence of spines) characteristics. A total of 26 morphotypes with different combinations of features, differing at least in one of 12 morphological characteristics, have been recorded. Based on original and literature data it is suggested to refer T. fenestrata, T. quadriseptata, T. ventricosa and T. pseudoflocculosa to the synonymy of T. flocculosa and extend the diagnosis of this species. New data on the morphology of T. fenestrata var. geniculata has been obtained. It is suggested to keep the taxonomic status of this form and broaden the diagnosis of the variety.
Key words: Tabellaria flocculosa, T. fenestrata, T. quadriseptata, T. ventricosa, T. pseudoflocculosa, morphology, taxonomy, rivers and lakes of Karelia, Russia.
INTRODUCTION
Tabellaria flocculosa is a widespread species (Diatoms..., 1951; Skabichevsky, 1960) and views on the volume of this species have been constantly changing. For example, a guidebook (Diatoms..., 1951) gives only the type variety, B. M. Knudson (1952) already gives several varieties for T. flocculosa. Krammer, Lange-Bertalot (1991) referred the majority of previously described varieties of T. flocculosa and T. fenestrata to the synonymy of type T. flocculosa (T. flocculosa var. ambigua Brigger, T. fenestrata var. intermedia Grunow, T. fenestrata var. asterionelloides Grunow, T. fenestrata var. geniculata A. Cleve, T. flocculosa var. pelagica Holmboe, T. fenestrata var. willei Haifedt-Kaas, T. fenestrata var. teilingii Knudson, T. flocculosa var. linearis Koppen), but continued to classify T. quadriseptata Knudson and T. ventricosa as independent species. Later some researchers kept recognizing independence of T. flocculosa var. linearis (Camburn, Charles, 2000; Siver et al., 2005; Zimmermann et al., 2010; Siver, Hamilton, 2011), but brought T. ventricosa to the synonymy of T. flocculosa (Genkal, Kharitonov, 2010). Besides, a variety T. flocculosa var. andina (Lange-Bertalot, 1993) and a new species T. pseudoflocculosa (Kobayasi et al., 2006) have been described over the last few years.
Different researchers give different sets of characteristics as distinguishing features between the similar species T. flocculosa and T. fenestrata. By key, the guide (Diatoms..., 1951) gives different widths of the central and terminal inflations as well as different numbers of intercalary bands and septa. For the identification of the similar species T. flocculosa, T. fenestrata and T. quadriseptat Knudson (1952) gives the morphology of colonies, number of septa, presence or absence of rudimentary septa, width of the central and terminal inflations, shape of the valve ends, the rimoportula position (mucilage pore) in the middle part of the valve. As key parameters to distinguish among the three above-mentioned species, Patrick, Reimer (1966) use the central and terminal inflation widths, number of septa and presence of rudimentary septa, position of mucus pores. Besides the above-mentioned characteristics, Krammer, Lange-Bertalot (1991) use additional distinguishing features for these three species — shape of the axial area in the valve center and presence of spines. According to these authors, a similar species T. ventricosa distinguishes from T. flocculosa, T. fenestrata and T. quadriseptata by the valve width and rimoportulae arrangement.
Different views on the volume and identification of the above-listed species of the genus Tabellaria pose certain problems with the identification of these species, especially using TEM and SEM. Therefore the study of variability of morphological characteristics in representatives of this genus and assessment of their taxonomic significance are important.
MATERIALS AND METHODS Phytoplankton samples for this study were collected in lakes and rivers of Karelia (Table 1, 2) characterized by mass development of T. flocculosa complex. The method of cold burning (Balonov, 1975) was used to clean diatom valves of organic matter. Preparations of algae were analyzed under a JSM-25S scanning electron microscope in the Center of Collective Use for Electron Microscopy, Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences.
* Corresponding author
Table 1. Geographic coordinates, hydrological and hydrochemical characteristics of the lakes under study (Catalogue..., 2001; Lakes..., 2013)
Waterbody Coordinates Drainage area, Area, Altitude, Basin Turbidity, Average X«. mg/1 pH Chromacity, Trophic state
N E km2 km2 m genesis m depth, m °Pt-Co scale
Baltic Sea basin
Onega Lakes 61°42' 35°25' 53 100 9720 33.3 tectonic 5-7 30.0 38.3 7.4 22 oligotrophic
White Sea basin
Topozero 65°38' 32°06' 2540 986 109.5 tectonic 4.5 15.9 13.4 6.8 17 oligotrophic
Alajarvi 65°29' 33°34' nd 7.35 nd nd nd 3.5 nd nd nd nd
Middle Kuito 65°07' 31°14' 9470 257 101 tectonic 3.2 10.4 19 6.6 35 oligotrophic
Shuezero 64°27' 33°58' 141 41.9 102.4 nd nd 5.4 26.8 6.8 19 mezotrophic
Note, nd — no data.
Table 2. Geographic coordinates, hydrological and hydrochemical characteristics of the lakes under study (Bersonov, 1960; Catalogue..., 2001; Surface..., 1965)
River Length, km Slope, %o Drainage area, km2 Ozernost, % Water discharge, m3/s Coordinates, N, E
source mouth
Kem' 357 0.61 28223 9.9 275.4 64°52', 31°56' 64°57', 31°42'
Chirko-Kem' 229 0.71 8228 9.3 88.9 63°49', 31°39' 64°45', 32°07'
Kolezma 87 1.30 756 4.0 6.49 63°48', 35°38' 64°14', 35°52'
Suma 158 1.11 2041 13.1 18.51 63°25', 35°55' 64°15', 35°24'
Table 3. Variability of the morphological features of Tabellaría flocculosa in the River Kem'
Morphotype Shape of terminal inflations Width of central inflation Spines Pseudoraphe in central portion Rimoportula position Number of rimoportulae Figure number
capitate not capitate greater than width of terminal inflations equal or less than width of terminal inflations present absent widened not widened in the middle of central inflation at the edge of central inflation (+) or intermediate (++)
1 nd + nd = + nd + nd + nd 1 3, 4, 28
2 nd + > nd + nd + nd + nd 1(2) 24, 26, 29,31,
32,37,39,41,
42
3 nd + nd = nd + + nd + nd 1(2)
4 nd + nd = + nd + nd nd + 1 1, 2, 27
5 nd + nd = + nd nd + nd + 1 34
6 nd + nd = nd + nd + + nd 1
7 nd + > nd nd + + nd + nd 1 17, 18
8 nd + > nd nd + + nd nd + 1 40
9 nd + > nd nd + nd + nd + 1 10, 11
10 nd + > nd nd + nd + + nd 1 5,6
11 nd + nd < nd + + nd nd ++ 1 22, 23
12 nd + > nd + nd nd + + nd 1 30
13 nd + > nd + nd + nd nd + 1 25, 33, 35, 36
14 + nd nd < nd + nd + + nd 1 7, 8, 13, 14
15 + nd > nd + nd + nd nd + 1 15, 16
16 + nd nd = + nd nd + nd + 1 19
17 + nd nd = + nd nd + + nd 1 9, 12, 20, 21
Note, nd — no data.
RESULTS
Variations in the valve size (length 17 to 159 ^.m), its shape and structural elements of T. flocculosa s.l. valve from the Kem' River are shown in Figs. 1-42. Figs. 16-29 show morphological variability of the valves which measure 90 ^.m in length and Figs. 33-42 — of the valves ranging from 17 to 30^m. In the samples under analysis, 15 morphotypes, differing at least in one of 12 morphological features, were detected (Table 3). Figs. 43-73 show variations in the valve size (length from 15.9 to 138 ^.m), its shape and structural elements of flocculosa s.l. valve from the Chirko-Kem' River. Variability of the valves from 62 to 68 ^m in length is shown in Figs. 62-68. A similar number of morphitypes (16) were found in the analyzed samples (Table 4). In other samples we observed different sets of morphotypes, including those found in rivers Kem' and Chirko-Kem' (Table 4): Topozero — 2 (2, 7), Alayarvi — 6 (4, 7, 14, 22, 23, 24), Shuezero — 7 (2, 8, 11, 13, 21, 25, 26), Sredneye Kuito — 10 (1, 2, 7, 8, 10, 12, 13, 18, 21, 27 ). Sometimes valves with two rimoportulae occurred in the analyzed samples (Figs. 31, 65).
In Lake Elgygytgyn we recorded only a few morphotypes (2, 12) but there was considerable variation in the number of rimoportulae and their arrangement on the valve: one process in the central (Figs. 75, 77, 79,
83) or terminal inflation of the valve (Fig. 78), two or three processes in the central inflation (Figs. 80-82, 84), one process between each central and terminal inflations (Fig. 76), one process near each terminal inflation (Fig. 85), two processes in the central inflation and one in the terminal inflation (Fig. 82). Spines were absent in some valves (Figs. 74-76, 80) and central area in the middle portion of the valve was not widened (Fig. 80,
84). In many cases the central inflation of the analyzed forms was about 10 ^.m (Figs. 75, 77-79, 83, 85) and 11.4 ^m in Fig. 84.
A total of 26 morphotypes with different combinations of features, differing al least in one of 12 morphological characteristics, were recorded (Table 3, 4). Interesting forms from other baterbodies under study are shown in Fig. 86-93. Fig. 86 shows a valve with asymmetrical halves, Fig. 87 — a valve of 12.2 ^.m in width, Fig. 88 — different shapes of the terminal inflations, Fig. 89 — a similar in shape and length valve from Topozero with spines as opposed to the one in Fig. 88. In some of the waterbodies under study, we observed single, evidently abnormal valves of an unusual shape (Figs. 92, 93).
Quantitative characteristics of the analyzed samples are shown in Table 5. The widest range of the valve length was recorded in samples from the Kem' River (7.5-159 ^.m). The minimum width of the central inflation (2.7 ^.m) was recorded in Shuezero and maximum — in the Kolezhma River (13.8 ^.m). The minimum terminal inflation (2.7 ^.m) were also recorded in Shuezero and maximum — in the Kolezhma River (9.5 ^m). The minimum number of striae in 10 ^m (12) were recorded in the majority of waterbodies under study and maximum (20) — in rivers Kem' and Chirko-Kem'.
There is a definite correlation between the valve length and the vale length/width ratio in all the studied populations — as the valve length increases the ratio increases as well (Fig.105 a-d).
There were forms in Topozero which we referred to T. flocculosa var. geniculata (Figs. 94-104, Tables 5, 6). Transitional valve forms from straight to knee-shaped were recorded in that lake. Axial area in the central inflation has or has no widening, spines are present, the only rimoportula is situated in the middle part of the central inflation or its margin (Fig. 104). It should be noted that these forms in Fig. 105e form a separate aggregate due to their wider valves.
DISCUSSION
Our data on the variability of quantitative features in the analyzed populations of T. flocculosa agree with the literature data (compare Table 5 and 7). Ranges of variation of these features in T. fenestrata, T. quadriseptata, T. pseudoflocculosa and T. ventricosa also coincide with those in T. flocculosa (compare Table 7 with 8, 9).
According to the published data, such features as the shape of colonies, number of septa and presence of rudimentary septa vary to a large extent and cannot be used as differential characteristics for the identification of T, flocculosa and T. fenestrata (Tables 7, 8). In the latest systematic summaries these features are absent in the diagnoses of the above-mentioned species (Zimmermann et al., 2010; Siver et al., 2011). Other features are used as differential characters for the identification of species of the genus Tabellaria: width of the central and terminal inflations, shape of the valve ends and axial area, presence of spines, number and arrangement of rimoportulae. According to the literature, in T. flocculosa var. flocculosa, T. flocculosa var. linearis, T. fenestrata and T. quadriseptata the valve shape varies — the medial inflation of the valve is wider or equal or very rarely smaller than the apical inflations (Tables 7, 8). Our data confirm this (Tables 3, 4, Figs. 1-73).
Table 4. Variability of the morphological features of Tabellaría flocculosa in the River Chirko-Kem' and other investigated waterbodies
Shape of terminal inflations Width of central inflation Spines Pseudoraphe in central portion Rimoportula position
Morphotype capitate not capitate greater than width of terminal inflations equal or less than width of terminal inflations present absent widened not widened in the middle of central inflation at the edge of central inflation (+) or intermediate (++) Number of rimoportulae Figure number
1 nd + nd = + nd + nd + nd 1 47, 48
2 nd + > nd + nd + nd + nd 1(2) 55, 56, 67, 70-74
3 nd + nd = nd + + nd + nd 1
4 nd + nd = + nd + nd nd + 1 63,64
5 nd + nd = + nd nd + nd + 1 68
6 nd + nd = nd + nd + + nd 1 51, 52
7 nd + > nd nd + + nd + nd 1 58, 60
8 nd + > nd nd + + nd nd + 1 61,62
13 nd + > nd + nd + nd nd +, ++ 1(2) 65,66
14 + nd nd = nd + nd + + nd 1 45, 46,51, 52
15 + nd nd = + nd + nd + nd 1 49, 50, 57, 59
18 nd + > nd + nd nd + nd + 1 43,44
19 + nd > nd ? nd nd + + nd nd 53, 54
20 + nd > nd + nd + nd + nd nd 55, 56, 69
21 + nd > nd nd + nd + + nd 1 Middle Kuito
22 nd + nd + nd + nd nd ++ 1 Alajarvi
23 nd + > nd + nd + nd nd ++ 1 Alajarvi
24 + nd > nd nd + nd + nd + 1 Alajarvi
25 nd + nd nd + + nd nd + 1 Shuezero
26 + nd > nd nd + + nd nd + 1 Shuezero
27 + nd nd = nd + nd + nd + 1 Middle Kuito 90, 91
Table 5. Morphological characteristics of Tabellaría flocculosa in the investigated waterbodies
Lenght, ^m Width of central inflation, ^m Width of terminal inflation, ^m Number of striae in 10 ^m Waterbody
T. flocculosa var. flocculosa
14.5-91 6.8-9.5 6.0-6.8 12-18 Suma
57.8-114 5.7-10 4.4-8 12-15 Onega Lake
35.7-126 4.7-12.2 4.7-6.5 12-18 Shuezero
28.6-140 5.3-8.9 4.4-8.4 12-18 Alajarvi
33.3-132 4.4-10 3.6-8.6 12-18 Middle Kuito
15.9-127 4.4-10 4.1-7.8 12-20 Chirko-Kem'
22.1-123 5.9-11 3.6-8.9 12-16 Topozero
7.5-159 4.7-10 3.6-9 13-20 Kem'
7.5-159 4.4-12.2 3.6-9.0 12-20 Total data
T. flocculosa var. geniculata
100-109 10-14.7 6.4-7.5 13-16 Topozero *
88-102 11.1-17.6 5.9-7.3 12-16 Topozero **
Note. * — straight-line valves; ** — geniculate valves.
In the analyzed samples, the shape of the ends changes from typical for T. flocculosa — subcapitate (for example, Figs. 1, 4, 5, 22-28, 30-42) to typical for T. fenestrata — strongly capitate (for example, Figs. 8, 12, 13, 19, 20). But there are valves, which ends shape is difficult to refer to the above mentioned types (Figs. 8, 16, 29, 50, 59, 69). Other researched give T. flocculosa and T. fenestrata valves with different shapes of their ends — distinctly capitate for T. flocculosa (Camburn, Charles, 2000, Pl. 10, Figs. 1, 2; Kobayasi et al., 2006, Pl. 110, Figs. 5, 8, 11, 14; Zimmermann et al., 2010, Pl. 6, Figs. 6, 7) or subcapitate for T. fenestrata (Ska-bichevsky, 1960, Fig. 109 e-g; Koppen, 1975, Fig. 17; Hustedt, 1985, Fig. 554 b, c; Stenina, 2009, Appendix 2, Photo Table 1, Fig. 6; Metzeltin et al., 2009, Pl. 8, Figs. 1-4), which is confirmed by published data (Tables 7-9). It should be noted that some researchers give illustrations of Tflocculosa valves with one end typical for T. fenestrata and the other — for T flocculosa (Knudson, 1952, Fig. 2 A, C; Bateman, Rushforth, 1984, Pl. 26, Fig. 360). Figs. 16, 17, 19, 20, 22 show variability of the valve ends in samples from the Kem' River for valves of 90 ^m in length, Figs. 27-30 — for 43-50 ^m valves, Figs. 31-35 — for 29-39 ^m valves, Figs. 36-42 — for 17-26 ^m valves and Figs. 63, 66-69 — for 46-66 ^m long valves in samples from the Chirko-Kem' River which prove high variability of this character. Illustrations of valves with a varying shape of their ends are also given in the description of T. quadríseptata (Knudson, 1952, Fig. 1, G-I), which is also confirmed by other researchers (Siver, Hamilton, 2011, Pl. 28, Figs. 1-6). In his work, Koppen (1975, Figs. 5, 6) gives illustrations of T. fenestrata valves with various degrees of terminal inflation. All these data suggests that this feature is variable, researchers interpret it differently and thus it cannot be used as a differential character for species of the genus Tabellaría. In other genera of rapheless diatoms there is considerable variation in the shape of the valve and its ends: Asteríonella formosa Hassal (Krammer, Lange-Bertalot, 1991, Taf. 103, Figs. 4-8), A. ralfsíí W. Smith (Genkal, Kulikovsky, 2003, Tables. I, 3-13), Díatoma tenue Agargh (Genkal, 2004), D. eh-renbergíí Kützing, D. moniliformis Kützing, D. anceps (Ehrenberg) Kirchner, D. problematíca Lange-Bertalot (Hofmann et al., 2011, Taf. 2, Figs. 6-10, 11-15, 20-24, 26-30), D. anceps (Patrick, Reimer, 1966, Pl. 2, Figs. 1-3), Hannaea arcus (Ehrenberg) Patrick (Krammer, Lange-Bertalot, 1991, Taf. 117, Figs. 8-13; Genkal, Kharitonov (2008, Fig. 10), Merídíon círculare var. constríctum (Ralfs) Van Heurck (Krammer, Lange-Bertalot, 1991, Taf. 101, Figs. 8-14).
As follows from Tables 3, 4, the shape of the axial area is also a variable feature and even in one sample it can be widened or not. This is confirmed by the literature data for T. flocculosa (Krammer, Lange-Bertalor, 1991, Taf. 106, Figs. 3, 5-9, 11; Lange-Bertalot, Metzeltin, 1996, Taf. 6, Figs. 7-9; Zimmermann et al., Pl. 6, Figs. 1-6, 8-14, Pl. 7, Figs. 1-10; Tables 7-9).
Spines can be present or absent on the valve (compare, Figs. 5, 6 and 9, 12; 13, 14 and 16; 80 and 82) or there are only few spines and they vary in size from noticeable (Fig. 81) to almost unnoticeable (Fig. 86). Such variability of this feature is confirmed by other researchers (Tables 7-9), which don't make it possible to use it as a differential characteristic. The variability of this character is also recorded in other genera of rapheless diatoms: Hannaea arcus (Genkal, Kharitonov, 2008), H. ínaequídentata (Genkal, Kharitonov, 2008), H. baícalensís Genkal, Popovskaya et Kulikovskiy (Genkal et al. 2008).
Table 6. Variability of the morphological features of Tabellaría flocculosa var. geniculata
Morphotype Shape of inflations Width of central inflation Spines Pseudoraphe in central portion Rimoportula position Number of rimoportulae Figure number
capitate not capitate greater than width of terminal inflations equal or less than width of terminal inflations present absent widened not widened in the middle of central inflation at the edge of central inflation (+) or intermediate (++)
1 + nd > nd + nd + + + + 1 94-97, 101, 102
2 + nd > nd + nd + + + + 1 98-100, 103,
104
Table 7. Variability of the morphological features of Tabellaría flocculosa from literature data
1 2 3 4 5 6 7 8 9 10 11 12
Tabellaría flocculosa var. flocculosa
Z many nd + nd nd 12-50 5-16 13-18 > Diatom...,1951
Z, St, c, p 2-32 and > frequently + +* nd nd 6-130 nd nd = or > Knudson, 1952
z, sometimes st to 20 and > nd sometimes + nd nd 12-50 5-16 -18 > Skabichevsky, 1960
Z many + - - nd nd <80, up to nd 14-18 frequently > Patrick, Reimer, 1966
130
z, partly st 2-4 and > + ± + + 1, in the midie of central 15-122 3.8-8.5 14-17 > Koppen, 1975
inflation
Z 3-32 nd ±* ± + 1, eccentric 6-130 3.8-8.5 13-20 > Krammer,
Lange-Bertalot, 1991
nd nd frequently + - + + 1, in the midie of central 12-60 3-7.5 14-21 > or = Siveretal., 2005
inflation
Z many nd nd - nd 1, in the midie of central 12-50 5-16 -18 > Hustedt, 1985
frequently + inflation
nd nd nd +* ±* 1, in the midie of central 10.6-163 5.7-10.7 11-22 >* Genkal, Trifonova,
inflation 2009
Z 3 and > 20 nd ± ± ± 1-4, strongly vary 6-130 3-16 10-21 > Genkal, Kharitonov,
2010
nd nd nd +* nd nd 11.7-39.3 6-10 12-22 > Zimmermann et al.,
+ 2010
nd nd nd +* ±* 1, in the midie of central 21.4-97 7-13 9-16 >* Genkaietal., 2011
inflation*
various form, nd nd ±* nd nd 6-130 4-8.5 13-20 >* Hofmannetal., 2011
more frequent z
nd nd + - + + 1, in the midie of central 31-66 3-7.5 15-21 > or = Siveretal., 2011
inflation
Table 7 (continued)
1 2 3 4 5 6 7 8 9 10 11 12
T. flocculosa var. andina
nd 4 and > + -? + + 1, in the midle of central 35-63 9.5-11 18-20* > Lange-Bertalot, 1993
inflation
nd nd nd +* nd nd 60* 9.3-10* 16* >* Rumrich et al., 2000
T. flocculosa var. geniculata
St nd nd +* nd 1, in the midle of central inflation 50* 9* 14* > Diatom..., 1951
P nd nd nd nd nd nd 40-63 nd nd > Knudson, 1953
St nd nd ? nd 1, in the midle of central inflation 40* 8* 16* > Skabichevsky, 1960
T. flocculosa var. linearis
Z 2 and > ± + 1, in the midle of central inflation, near the margin or in short distance from central inflation 40-146 4.7-6.6 13-20 or < Koppen, 1975
nd nd frequently + — — + 1, in the midle of central inflation 30-50 4-6 15-20 > or = Siver et al., 2005
nd nd nd — nd nd 43.3-66 5.3-6.0 13-18 > Zimmermann et al., 2010
nd nd frequently + - - + 1, vary 33-77 5.5-7 18-20 > or = Siver etal., 2011
Note (Tables 7-9). 1 — colony morphology: z — zigzag, st — star, c — corkscrew, p — parachute-shaped, s — straight-line; 2 — number of septa; 3 — present of rudimentary septa: + present, - absent; 4 — shape of the terminal inflations: + distinct capitate, - not capitate; 5 — pseudoraphe in central portion: + widened, - not widened; 6 — presence of spines: + present, - absent; 7 — number and position of rimoportulae; 8 — lenght of valve, |im: 9 — width, |im: 10 — number of striae in 10 |im: 11 — width of central inflation: = equal to width of terminal inflation, > more to width of terminal inflation, less to width of terminal inflation; 12 — source;* — according to measured on microphotographs; + — present;--absent; nd — no data.
Table 8. Variability of the morphological features of Tabellaría fenestrata from literature data
1 2 3 4 5 6 7 8 9 10 11 12
Z, St S Z, St s, z nd Z nd S 4 2-4 4-8 4 4 4 nd 4 or < nd nd nd nd nd +* + ± +* nd +* + + - sametimes + sametimes + sametimes + nd nd nd nd nd nd Tabellaría fenestrata nd nd nd 1, in the midle of central inflation 1, in the midle of central inflation* 1, in the midle of central inflation nd 1, in the midle of central inflation 30-140 25-116 30-140 38-103 (25)33-116 30-140 33-116 25-116 3-9 nd 3-9 5.6-8.5 4-10 3-9 4-10 5-10 18-20 15-18 18-20 17-22 (14)17-22 18-20 (14)17-22 14-18 > =* > Diatom..., 1951 Knudson, 1952 Skabichevsky, 1960 Koppen, 1975 Krammer, Lange-Bertalot, 1991 Hustedt, 2007 Hofmannetal., 2011 Patrick, Reimer, 1966
Table 9. Variability of the morphological features of Tabellaría quadriseptata from literature data
1 2 3 4 5 6 7 8 9 10 11 12
Z nd nd nd 2-4 nd nd nd nd nd frequently + nd nd ±* +* +* +* nd +* + nd Tabellaría quadriseptata 1, near the margin of central inflation 1, in the middle of central inflation 1, near the margin of central inflation nd 23-129 23-130 40-58 53-87 nd 6-9 4-5 4.5-7 14-18 13-20 15-18 17-20 >* >* =* >* Knudson, 1952 Krammer, Lange-Bertalot, 1991, Siveretal., 2005 Siver, Hamilton, 2011
z* nd nd +* + T. pseudoflocculosa 1, in the midle of central inflation or near the margin of central inflation 35-15 5-6.5 -16 >* Kobayasi et al., 2006
nd nd nd nd nd nd +* +* nd nd T. ventricosa 1, seldom 2 at terminal inflations 1, seldom 2 at terminal inflations 20-32* nd (7*)10-16 10-16 12-16* nd > > Krammer, Lange-Bertalot, 1991 Hofmann et al., 2011
Figs. 1-21. Tabellaria flocculosa (Kem' River). SEM external (Figs. 1, 2, 5-9, 12-16, 19-21) and internal (Figs. 3, 4, 10, 11, 17, 18) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 1, 4, 5, 8, 11-13, 16, 17, 19, 20); 5 ^m (Figs. 2, 3, 6, 7, 9, 10, 14, 15, 18, 21).
Figs. 22-37. Tabellaría flocculosa (Kem' River). SEM external (Fig. 33) and internal (Figs. 22-32, 34-37) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 22, 25-28); 5 ^m (Figs. 23, 24, 29-37).
Figs. 38-54. Tabellaria flocculosa (Figs. 38-42 — Kem' River, Figs. 43-54 -Chirko-Kem' River). SEM external (Figs. 43-52) and internal (Figs. 38-42, 53, 54) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 43, 46, 47, 50, 51, 54); 5 ^m (Figs. 38- 42, 44, 45, 48, 49, 52); 1 ^m (Fig. 53).
Figs. 55-73. Tabellaría flocculosa (Chirko-Kem' River). SEM external (Figs. 61, 62, 68) and internal (Figs. 55-60, 6367, 69-73) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 55, 58, 59, 62, 63, 66-68); 5 ^m (Figs. 56, 57, 60, 61, 64, 65, 69-72); 2 ^m (Fig. 73).
Figs. 74-86. Tabellaria flocculosa (Figs. 74-85 — Elgygytgyn Lake, Fig.86 — Topozero Lake). SEM external (Figs. 79, 81, 82, 86) and internal (Figs. 74-78, 80, 83-85) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 74-78); 5 ^m (Figs. 79-86).
Figs. 87-104. (Figs. 87-93 — T. abellaria flocculosa var. flocculosa, Figs. 94-104 — T. flocculosa var. geniculata (Figs. 87, 92 -Shuezero Lake, Figs. 88, 89, 94-104 — Topozero Lake, Fig. 88 — Middle Kuito Lake, Fig. 93 — Vozhma River). SEM external (Figs. 87-89, 93, 95, 97, 100, 101) and internal (Figs. 90-92, 94, 96, 98, 99, 102-104) views (rimoportula position arrows). Scale bars 10 ^m (Figs. 88-90, 92-100); 5 ^m (Figs. 87, 91, 101-104).
According to most published data, in T. flocculosa var. flocculosa, T. flocculosa var. andina, T. flocculosa var. linearis, T. fenestrata, T. quadriseptata and T. pseudoflocculosa there is only one rimoportula in the middle part of the valve. An exception is T. ventricosa (syn.: T. flocculosa var. ventricosa Grunow), which some researchers recognize as an independent species (Krammer, Lange-Bertalot, 1991; Hofmann et al., 2011). In earlier works, T. flocculosa var. ventricosa was referred as a synonym of the type variety (Skabichevsky, 1960; Hustedt, 1985) and recently T. ventricosa has been brought to the synonymy of T. flocculosa again (Genkal, Kharitonov, 2010). According to the diagnosis, in T. ventricosa there are more processes and they are located at the ends of the valve. Usually there is one, rarely two processes on each end. (Table 9). As differential features, these researchers (Krammer, Lange-Bertalot, 1991; Hofmann et al., 2011) give larger width of the valve (10-16 ^m) and the valve length/width ratio less than 3:1. They give no data on the valve length and number of striae in 10 ^m. According to micrograph measurements of T. ventricosa (Krammer, Lange-Bertalot, 1991, Taf. 107, Figs. 1-7), its valve length varies from 10 to 32 ^m, the minimum width is 7 ^m and the number of striae in 10 ^m ranges from 12 to 14. The valve of minimum length and width (Krammer, Lange-Bertalot, 1991, Taf. 107, Fig. 7) is very similar to T. flocculosa valves of a small length (compare Figs. 32, 71, 79, 83, 84), which is confirmed by the literature data (Skabichevsky, 1960, Fig. 108 k; Lange-Bertalot, Metzeltin, 1996, Taf. 6, Fig. 9; Koppen, 1975, Fig. 9, 26; Camburn, Charles, 2000, Pl. 10, Figs. 9, 11, 12; Siver et al., 2005, Pl. 22, Fig. 4; Metzeltin et al., 2009, Pl. 8, Fig. 7; Zimmermann et al., 2010, Pl. 7, Figs. 4, 5, 7, 8; Siver, Hamilton, 2011, Pl. 28, Figs. 10, 11). In our material, the valve from Shuezero (Fig. 87), 40 ^m in length and 12.2 ^m in width, were the most similar in shape. However, the only rimoportula position was not typical for T. ventricosa. According to our data, in populations from Lake Elgygytgyn basin, the number of rimoportulae varies from 1 to 3 and they are arranged along the whole valve face (Figs. 74-85). In our material from Lake Elgygytgyn, the valve width in forms similar to T. ventricosa ranges from 10 to 11.4 ^m, number of striae in 10 ^m varies from 12 to 16 and the rimoportula arrangement typical for T. ventricosa is recorded in valves of 47-37 ^m long and 8-10 ^m in width (Figs. 74-76) as well as in shorter valves of 23-33 ^m in length (Figs. 78, 85). Fig. 105 presents the distribution of T. ventricosa and T. flocculosa valves, given as illustrations of these species (Krammer, Lange-Bertalot, 1991, Taf. 107, Figs. 1-7), which shows that the valves of the latter species have the same length/width ratio as in T. ventricosa. In the analyzed material, valves with this ratio less than 3:1 occur in all the populations (Fig. 105). The aforecited data suggest that the length/width ratio cannot be used as a differential feature to identify T. ventricosa. Original and literature data show a significant morphological variability of T. flocculosa and support the view of some authors that T. ventricosa forms circle belongs to T. flocculosa. Variations in the rimoportula arrangement are also recorded in other representatives of rapheless diatoms: Asterionella ralfsii (Genkal, Kulikovsky, 2003, Tables I, II; Genkal, Kharitonov, 2008, Fig. 2), Hannaea inaequidentata (Lagersted) Genkal et Kharitonov (2008, Fig. 4).
T. flocculosa var. andina Lange-Bettalot, in its author's opinion, differs from other varieties in a greater width of the central inflation of the valve (Table. 7). Knudson (1953, Fig. 5 H-L) gives similar forms under the name of T. flocculosa. According to his data, the length of these valves ranges from 41 to 52 ^m but our measurements show it varies towards greater values — 55-66 ^m and width ranges from 10 to 14 ^m. This shape valves (Figs. 94, 95) we recorded in Topozero, they had a greater length, a wider range of variability of the valve width, and a smaller number of striae in 10 ^m (Table 5). The rest of the features (presence of spines, shape of axial area, number and arrangement of rimoportulae) coincided with those of T. flocculosa var. andina. We recorded the same valve in the Kolezhma River (length 100 ^m, width 13.2 ^m, number of striae in 10 ^m 14). In Shuezero we found a valve very similar to those of T. flocculosa var. andina (Fig. 92). Forms, transitional to T. flocculosa var. geniculata with slight asymmetry of the terminal and central inflations, occur in Topozero (Figs. 96, 97, 102). Knudson (1953, Fig. 5 D-G) refers them to the morphological series T. flocculosa var. geniculata. It would be logical to assume that straight valves without asymmetry of their ends and the middle are in the beginning of this series and knee-shaped valves are in its end. However, the fact that sometimes only straight valves occur suggests that there is a separate variety of T. flocculosa var. andina and molecular genetic investigations are needed to clarify independence of this variety. Krammer, Lange-Bertalot (1991) brought T. flocculosa var. geniculata to the synonymy of the type variety. From the other hand, Lange-Bertalot (1993) described a new variety T. flocculosa var. andina based on a greater width of the valve. In our opinion, based on the same characteristic and the valve shape, T. flocculosa var. geniculata should be left as a variety, which is confirmed by the distribution of analyzed populations in the valve length and length/width ratio coordinates when T. flocculosa var. andina and T. flocculosa var. geniculata valves form a separate aggregate (Fig. 105 c).
30 20 10 0
i - v A
A * ■A
A-" k 4
0 50 100 150
Alajarvi ■ Shueozero
30
20
10
r^r
0 50 100 150
Topozero 2 ■ Topozero 1
40 30 20 10 0
■ ■ A
k\ - 1 A *
0 50 100 150 200 Middle Kuito a Kem
30
20
10
i j . A
m A 'i
0 50 100 150
Elgygytgyn A Chirko-Kem
20
10
■ ■
■ ■ ■ A
0 50 100
(Krammer) T. flocculosa (Krammer) T. ventricosa
Fig. 105. Relations between the valve diameter (horizontal axiz, ^m) and the length/width ratio (vertical axis). Krammer — according to measured on microphotographs from Krammer, Lange-Bertalot, 1991.
T. flocculosa var. linearis was referred to the synonymy of the type variety (Krammer, Lange-Bertalot, 1991), but some researchers recognize its independence (Camburn, Charles, 2000; Siver et al., 2005, 2011; Zimmermann et al., 2010). The dimensional characteristics and number of striae in 10 ^m in this variety coincide with those in the type variety and differ from the type T. flocculosa var. linearis by equal widths of the central and terminal inflations or the latter even smaller than the medial one and the absence of the axial area widening in the middle part of the valve (Koppen, 1975; Table 7). It should be noted that very similar illustrations of T. flocculosa var. linearis and T. fenestrata (compare Koppen, 1975, Fig. 11 and Fig. 17) and T. flocculosa var. linearis and T. flocculosa var. flocculosa (compare Fig. 2 and Figs. 37-44) are presented in this publication. In our material the following forms could be referred to T. flocculosa var. linearis: the form in Figs. 5, 6 (but the valve lacks spines typical for the variety), the form in Figs. 13, 14 with the terminal inflations wider than the central one (but here the ends are strongly capitate and there are no spines), the form in Figs. 17, 18 (but here the central area is widened), the form in Figs. 22, 23 with the apical inflations is broader than the central inflation (but here there are no spines and the central area is widened), the form in Fig. 25 (but here the width of the central inflation is greater than the terminal ones, the form in Figs. 43, 44 (but here the central area is widened). By the valve shape and other features (no inflation of the axial area, rimoportula arrangement, presence of spines) T. flocculosa var. linearis is similar to c T. quadriseptata (compare Kopper, 1975, Fig. 2, 11 and Knudson, 1952, Fig. 1 G). Krammer, Lange-Bertalot (1991, Taf. 106, Fig. 3), Lange-Bertalot, Metzeltin (1996, Fig. 7), Camburn, Charlrs, (2000, Pl. 9, Fig. 24), Hofmann et al., (2011, Taf. 3, Fig. 1) give illustrations of T. flocculosa var. flocculosa valves similar to T. flocculosa var. linearis. Camburn, Charles (2000, Pl. 10, Figs. 14-20) give photographs of T. flocculosa var. linearis valves with terminal inflations of a totally different
0
0
0
shape. Zimmermann et al., (2010, Pl. 7, Figs. 11-13) give illustrations of T. flocculosa var. linearis valves which central inflation is wider than at the apical inflations, axial area is widened and capitate ends are more expressed. The above mentioned facts indicate to a wide variability of the differential features in T. flocculosa var. linearis and confirm Krammer, Lange-Bertalot's (1991) opinion about referring this variety to the synonymy of T. flocculosa var. flocculosa.
The following features are characteristic of T. fenestrata: strongly capitate valve ends, equal widths of the central and terminal inflations, the axial area in the center is not widened, spines are absent, however some researchers give other features (Table 8). In the analyzed samples, forms in Figs. 45, 46, 51, 52 can be referred to this species. By the shape of the valve ends and equal widths of its medial and apical inflations, forms in Figs. 9, 12, 20, 21, 50, 89 could be referred to T. fenestrata but these valves have spines. Similar forms are given in Figs. 5, 6, 53, 54 (but the central inflation of the valve is wider than the terminal inflations), 13, 14 (but the central inflation is smaller than the apical ones), 15, 16 (but the medial inflation is wider than the terminal inflations, spines are present and the rimoportula is located at the margin of the middle widening), 29, 88 (but width of the central inflation is greater than width of the terminal ones), 90, 91 (but the rimoportula is located at the margin of the middle widening). The foregoing illustrates a wide variability of the above listed differential features for T. fenestrata, which gives us grounds to consider this species to be conspecific with T. flocculosa.
The shape of the valve ends (subcapitate), equal widths of the central and terminal inflations, and the rimoportula location near the margin of the medial inflation are T. quadriseptata characteristic features (Knud-son, 1952). However, this work is illustrated with valves which have a wider middle part and such forms are given by other researchers as well (Siver et al., 2005, Pl. 22, Fig. 10; Siver, Hamilton, 2011, Pl. 29, Figs. 13). The ends shape varies from similar to that of T. flocculosa (compare Knudson, 1952, Fig. 1 G and Bateman Rushforth, 1984, Pl. 26, Fig. 360; Krammer, Lange-Bertalot, 1991, Taf. 106, Fig. 3; Lange-Bertalot, Metzeltin, 1996, Taf. 6, Fig. 7) or T. flocculosa var. linearis (compare Knudson, 1952, Fig. 1 G and Koppen, 1975, Figs. 2, 11; Knudson, 1952, Fig. 1 H and Siver, Hamilton, 2011, Pl. 29, Fig. 7) to valves with weakly noticeable terminal inflations (Knudson, 1952, Fig. 1 I). Siver, Hamilton (2011, Pl. 29, Figs. 1-12) give illustrations of T. quadriseptata and T. flocculosa var. linearis which, in our opinion, could be referred to one of the above mentioned taxa — T. quadriseptata. And now let's consider the last feature — the rimoportula arrangement. By this characteristic the forms in Figs. 1, 2, 25, 27, 36, 43, 44, 63, 64, 90, 91 could be referred to this species. Figs. 25-28 and 63-68 show valves of a similar length and shape with the rimoportula arrangement varying from its usual position in the central inflation of the valve to typical for T. quadriseptata, and in samples from Lake Elgygytgyn, an even higher variability in the number and location of rimoportulae is shown. Therefore this feature cannot be used as a differential characteristic for species of the genus Tabellaria. Based on these data we believe that T. quadriseptata should be brought to the synonymy of T. flocculosa. Knudson (1952) noted that collections of diatoms, examined by him and containing T. fenestrata by description, in fact contained long algae T. flocculosa and pointed out to a high variability of T. flocculosa valve and its similarity with T. quadriseptata and T. fenestrata. According to Knudson (1954), in 200 studied water objects of English Lake District, T. flocculosa was the most frequent and quite often occurred together with T. fenestrata, less frequently — with T. quadriseptata.
T. pseudoflocculosa is a non-valid species because there is no Latin diagnosis in its description. Quantitative and qualitative characteristics of T. pseudoflocculosa coincide with those of T. flocculosa (Tables 7, 9), but judging by the illustrations (Kobayasi et al., 2006, Pl. 112, Figs. 1-6), valves of this species taper towards the ends only slightly. Such forms, under the name of T. flocculosa are given by Knudson (1952, Fig. 2 A-D), Bateman, Rushforth (1984, Pl. 26, Fig. 361), Krammer, Lange-Betalot (1991, Taf. 106, Figs. 4-6), Lange-Bertalot, Metzeltin (1996, Taf. 6, Fig. 8), Siver et al. (2005, Pl. 22, Figs. 1-6), Hofmann et al. (2011, Pl. 3, Figs. 3-5) and Koppen (1975, Fig. 29) and Metzeltin et al. (2009, Pl. 8, Figs. 1-4) give them under the name of T. fenestrata.
Our investigations and the literature data show different views on the volume of taxa of the genus Tabellaria, identification of its forms and high variability of morphological features in representatives of this genus, which give us grounds to extend the diagnosis of T. flocculosa and its varieties and refer some species and intraspecific taxa to the synonymy of T. flocculosa.
Tabellaria flocculosa (Roth) Kutzing emend. Genkal var. flocculosa — Tabellaria flocculosa (Roth) Kutzing 1844, p. 127, pl. 17, fig. 21.
Synonyms: T. fenestrata (Lyngbye) Kutzing, T. ventricosa Kutzing, T. flocculosa v. ambigua Brigger, T. fenestrata var. intermedia Grunow, T. fenestrata var. asterionelloides Grunow, T. flocculosa var. pelagica Holmboe, T. fenestrata var.willei Haifedt-Kaas, T. fenestrata var. teilingii Knudson, T. quadriseptata Knud-son, T. flocculosa var. linearis Koppen, T. pseudoflocculosa H. Kobayasi ex Mayama.
Cells rectangular in girdle view. Colonies zigzag, star, corkscrew or straight — line, frustule with 2-32 septa or more, rudimentary septae present or absent. Valves linear, with +/- strongly inflated middle, central inflation often wider than apical ones or equal, rare narrower. Terminal inflations gradually tapering towards the shaft or distinctly capitate, 6-163 ц long, 3-16 ц wide. Transapical striae delicate, but distinct, 10-22 in 10 ц, perpendicular to the middle line but slightly radial on the ends. Pseudoraphe narrow or widened in the middle. Rimoportulae (1-4) (mucilage pores) situated in all valve surface, but frequently in central inflation. Spines are present or absent.
T. flocculosa var. geniculata (A. Cleve) Knudson emend. Genkal — T. flocculosa var. geniculata (A. Cleve) Knudson 1952, p. 437.
Synonyms: T. fenestrata var. geniculata A. Cleve, T. fenestrata subsp. geniculata (A. Cleve) Skabitsch., (?)T. flocculosa var. andina Lange-Bettalot.
Colonies parachute shaped or star. Valves geniculate or straight, terminal inflations gradually tapering towards the shaft or distinctly capitate, 40-109 ц long, 8-17.6 ц wide, striae 12-16 in 10 ц. Pseudoraphe narrow or widened in the middle. Rimoportula situated in central inflation. Spines are present or absent.
ACKNOWLEDGEMENTS This work was supported by Russian Science Foundation (№ 14-14-00555).
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К МОРФОЛОГИИ И ТАКСОНОМИИ TABELLARIA FLOCCULOSA
(BACILLARIOPHYTA)
С. И. Генкал1, Т. А. Чекрыжева2
'Институт биологии внутренних вод им. И. Д. Папанина РАН 152742, Ярославская обл., Некоузский р-н, пос. Борок, e-mail: algogus@yandex.ru Институт водных проблем Севера КарНЦ РАН 185003, Респ. Карелия, г. Петрозаводск, просп. Александра Невского, 50, e-mail: tchekryzhevas@mail.ru
Изучение комплекса T. flocculosa/T. fenestrata из озёр и рек Карелии (Россия) выявило широкую морфологическую изменчивость количественных (длина створки, ширина средней части и концов створки, число штрихов в 10 мкм, число двугубых выростов на створке) и качественных (форма створки и осевого поля, расположение двугубых выростов, наличие шипов) признаков. Всего в исследованных выборках зафиксировано 26 морфотипов с разным сочетанием признаков различающихся хотя бы по одному из 12 морфологических признаков. На основе оригинальных и литературных данных предлагается T. fenestrata, T. quadriseptata, T. ventricosa и T. pseudoflocculosa свести в синонимику к T. flocculosa и расширить диагноз этого вида. Получены новые данные по морфологии T. fenestrata var. geniculata, предлагается сохранить таксономический статус этой формы и расширить диагноз разновидности.
Ключевые слова: Tabellaria flocculosa, T. fenestrata, T. quadriseptata, T. ventricosa, T. pseudoflocculosa, морфология, таксономия, реки и озёра Карелии, Россия.
