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Article

Revision of Monoraphid Diatom Genus Platessa with Description of Platesiberia gen. nov. from Ancient Lake Baikal

by
Maxim S. Kulikovskiy
1,*,
Anton M. Glushchenko
1,
Sergei I. Genkal
2,
Irina V. Kuznetsova
1 and
John Patrick Kociolek
3
1
К.А. Timiryazev Institute of Plant Physiology RAS, IPP RAS, 35 Botanicheskaya St., 127276 Moscow, Russia
2
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, 152742 Borok, Russia
3
Museum of Natural History, Henderson Building, 15th and Broadway, Boulder, CO 80309, USA
*
Author to whom correspondence should be addressed.
Water 2022, 14(19), 2957; https://doi.org/10.3390/w14192957
Submission received: 17 August 2022 / Revised: 13 September 2022 / Accepted: 16 September 2022 / Published: 21 September 2022
(This article belongs to the Special Issue Species Richness and Diversity of Aquatic Ecosystems 2.0)
Browse Figures
Versions Notes

Abstract

:
A new monoraphid diatom genus, Platesiberia gen. nov., is described based on a detailed morphological investigation using light and scanning electron microscopy. The genus is based upon P. rhombicolanceolata Kulikovskiy & Lange-Bertalot and includes Platessa baicalensis Kulikovskiy & Lange-Bertalot, both species previously described from ancient Lake Baikal. Platesiberia gen. nov. is characterized by having biseriate striae on the raphe valves with uniseriate striae on the rapheless valves. Morphology of striae is helpful to distinguish the genus Platesiberia from Platessa and other monoraphid genera, and we provide a comparison of the new Baikalian genus with other freshwater monoraphid groups.

1. Introduction

Over the past 25 years the monoraphid diatoms have been the focus of intense research on their diversity, taxonomy and systematics. Whereas 2–3 generations ago, the freshwater representatives of monoraphid diatoms were treated as two genera, Achnanthes Bory and Cocconeis Ehrenberg [1,2,3], now there are over 14 genera of freshwater monoraphid diatoms that were once considered part of or assignable to Achnanthes sensu lato [4,5,6,7,8,9,10,11,12]. This discovery of diversity amongst the freshwater achnanthioid diatoms, both through recognition of past genera and newly discovered taxa, has been facilitated by observations made with scanning electron microscopes, revealing morphological features and patterns not previously recognized. New species descriptions from the world over have shown many consistencies in the distribution of the features used to diagnose new genera of monoraphid diatoms. However, there have also been some “intermediate” species recognized that might serve to link genera previously recognized as separate [13,14]. Molecular data have revealed that there have been several different, independent lineages within which the monoraphid condition has evolved [9,15], while many of the newly created and resurrected genera have been shown to be monophyletic [9].
More than 1500 species of diatoms inhabit Lake Baikal [7,8,9,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. During a revision of the monoraphid diatoms from Lake Baikal, about 55 new species were described [7,8,35,36]. Karayevia Round & Bukhtiyarova 1998, Skabitschewskia Kulikovskiy & Lange-Bertalot 2015, Nupela Vyverman & Compère 1991 and Planothidium Round & Bukhtiyarova 1996 have the greatest diversity of species among the monoraphid diatoms in the world’s oldest lake [8]. During this revision, many new monoraphid taxa were described from the genera: Eucocconeis P.T. Cleve ex F. Meister 1912, Karayevia, Nupela, Planothidium, Platessa Lange-Bertalot 2004 [8], Skabitschewskia, Trifonovia Kulikovskiy & Lange-Bertalot 2012 and Gliwiczia Kulikovskiy, Lange-Bertalot & Witkowski 2013. Two species of the diatom genus, Platessa, P. baicalensis Kulikovskiy & Lange-Bertalot and P. rhombicolanceolata Kulikovskiy & Lange-Bertalot, were described during this revisionary work [8].
In the last revision of the genus Platessa Lange-Bertalot, we indicated that eight groups within the genus could be recognized on the basis of morphological features [9]. Two interesting species previously described and placed in the genus Platessa stood out as a separate group [9]. This group includes both P. baicalensis and P. rhombicolanceolata [8], which are characterized by having biseriate striae on the raphe valve and uniseriate striae in rapheless valves. Most Platessa species have biseriate striae on both valves. In light of this difference, we postulated that the morphology of these species differs from the generitype of Platessa, P. bavarica Lange-Bertalot & Hofmann [37] and thus may require an independent genus to accommodate them [9]. It is interesting that Lake Baikal harbors taxa that do not share important morphological features typical of the generitype.
We have also carefully described all morphological features important for the taxonomy of monoraphid diatoms and postulated striae that are uniseriate, biseriate or multiseriate on the raphe and rapheless valves, as well as combinations of these features, which are important for the taxonomy of this group of diatoms. The same opinion was supported by molecular investigations for species and genera of monoraphid diatoms when possible [11,38,39,40,41,42]. Lange-Bertalot [37] proposed Platessa on the basis of morphological features with predominantly biseriate striae in both valves and small, elliptic, flat valves with morphologically similar raphe and rapheless valves; the presence of a stauros-like structure on the rapheless valves; and areolae of both valves occluded by hymenes. Since its original description, Platessa has become a catch-all genus with taxa representing many monoraphid genera with unknown taxonomical positions [9,43].
The aim of this publication is to provide additional morphological evidence for two monoraphid diatoms, Platessa baicalensis Kulikovskiy & Lange-Bertalot and P. rhombicolanceolata Kulikovskiy & Lange-Bertalot, and, based on the results of this study, to describe the genus Platesiberia gen. nov.

2. Materials and Methods

For this study we used samples from Lake Baikal collected by A.P. Skabitschewsky on 20 July 1965 from bottom deposits surrounding Ushkan’i Islands, obtained from the collection of Galina Khursevich (Minsk, Belarus). For a complete list of samples, please consult Kulikovskiy et al. [36]. The genus proposed here is based on species present in two samples: sample number 15,645 m—substratum: sand, Ushkan’i Islands 42 m depth, off Bolshoi Ushkan’i Island—and sample number 15,651 m—substratum: sand, Ushkan’i Islands 4 m depth, eastern shore.
The samples were boiled in concentrated hydrogen peroxide (≈37%) to dissolve organic matter. The samples were then washed with deionized water four times at 12 h intervals. After decanting and rinsing with up to 100 mL of deionized water, the suspension was spread onto coverslips and left to dry at room temperature. Permanent diatom slides were mounted in Naphrax®. Light microscopic (LM) observations were performed with a Zeiss Scope A1 microscope equipped with an oil immersion objective (100×, n.a. 1.4, differential interference contrast [DIC]) and Zeiss AxioCam ERc 5s camera. For scanning electron microscopy (SEM), parts of the suspensions were fixed on aluminum stubs after air-drying. The stubs were sputter coated with 50 nm of gold. Valve ultrastructure was examined by means of a JSM-6510LV scanning electron microscope (Institute for Biology of Inland Waters RAS, Borok, Russia).

3. Results

Platesiberia Kulikovskiy, Glushchenko, Genkal & Kociolek gen. nov.
Type species (designated here):Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov.
Description. LM, raphe valves (Figure 1A–H). Valves elliptical to rhombical-lanceolate, ends broadly rounded in longer specimens and somewhat cuneately rounded in shorter specimens. Valves with straight, filiform raphes which are gradually expanded towards the central ends. Axial area more or less widely extended transapically defined by 1–4 irregularly shortened adjacent striae. Striae radiate and biseriate.
LM, rapheless valves (Figure 1I–P). Valves elliptical to rhombical-lanceolate, ends broadly rounded in longer and somewhat cuneately rounded in shorter specimens. Axial area widely extended transapically. The central area is almost absent and defined by 1–2 shorter striae. Striae uniseriate.
SEM, raphe valves (Figure 2A–H). Axial area flat, central area expanded on flat valve and organized by elevated interstriae outside. Axial area elevated internally, sternum evident, central area has evident stauros that is defined by highly elevated interstriae between shorter 1–2 striae. Striae biseriate and covered by silica membrane externally. Raphe filiform, distal raphe ends are tear-shaped, extending slightly onto valve mantle and turned in opposite directions externally. Internally, raphe is filiform, distal and central ends are turned to different sides. Central raphe ends are tear-shaped, straight externally and almost straight internally.
SEM, rapheless valves (Figure 3A–H). Interstriae very prominent, the same width as striae internally. Externally valves are flat, but the central area has elevated interstriae between a few shorter striae. Striae uniseriate. Axial area broad and widened towards the central area. Sternum evident and elevated internally.
Etymology. Combining epithet refers to the similarity with the genus Platessa and the locality from Eastern Siberia (Lake Baikal).
New combinations:
Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov.
Basionym: Platessa rhombicolanceolata Kulikovskiy & Lange-Bertalot 2015. Lake Baikal: Hotspot of endemic diatoms II. Iconographia Diatomologica. V. 26. pp. 67–68. Figs 75: 11–13.
Platesiberia baicalensis (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. (see Figure 4).
Basionym: Platessa baicalensis Kulikovskiy & Lange-Bertalot 2015. Lake Baikal: Hotspot of endemic diatoms II. Iconographia Diatomologica. V. 26. pp. 64–65. Figs 75: 1–10.

4. Discussion

Platesiberia gen. nov. is a new genus that is very easily distinguished from other known freshwater monoraphid genera such as Platessa, Achnanthidium, Skabitschewskia, Planothidium, Crenotia, Eucocconeis, Gliwiczia, Lemnicola, Psammothidium, Trifonovia and Platebaikalia (see Table 1 and Table 2) [6,9]. Our new genus is distinguished from other freshwater monoraphid genera on the basis of striation on both raphe and rapheless valves. Platesiberia gen. nov. is characterized by the presence of biseriate striae on raphe valves and uniseriate striae on rapheless valves, separating it from Platessa as typified by P. bavarica. Our new genus is somewhat similar to the genus Lemnicola on the basis on shape of the valve, which are elliptical or rhombical-elliptical.
However, Lemnicola is very easily distinguished by having areolae that are biseriate on both valves. Skabitschewskia is another genus described from Lake Baikal, but species from this taxon are known from Holarctic. This genus is like Platesiberia gen. nov. valves with uniseriate and biseriate valves, but they occur in opposite placements. In Skabitschewskia, biseriate striae are known in the rapheless valves, and uniseriate striae are found on the raphe valves. Moreover, Skabitschewskia is characterized by the presence of a cavum on the rapheless valves. The cavum is an important morphological feature and is absent in Platesiberia gen. nov. Another genus with a cavum is Planothidium, and this genus is also characterized by having multiseriate striae on both valves [9,44,45].
Another genus having a cavum is Gliwiczia, but unlike the condition seen in Skabitschewskia and Lemnicola, the cavum is present on both the raphe and rapheless valves [7]. Gliwiczia is characterized by having uniseriate striae on both valves like in other genera without a cavum. These other genera include Trifonovia, Psammothidium, Eucocconeis, Achnanthidium, Gololobovia and Gogorevia [8,10,11].
A very interesting feature of Platesiberia gen. nov. is the presence of a stauros that is evident externally and internally. However, this stauros has distinct interstriae in the central part between shorter striae. This structure is evident in raphe valves but less so in rapheless ones. A stauros, seen in Platesiberica, is also known in the monoraphid genera Gliwiczia, Lemnicola, Gololobovia and Gogorevia [7,9,10,38].
The stauros is much more evident in the genus Gogorevia, which is closely related to Lemnicola on the basis molecular data [10]. We can postulate that a stauros is not common among monoraphid freshwater diatom genera and that the morphology of this structure in the genus Platesiberia gen. nov. is unique. We need more molecular phylogenetic investigations to understand evolution of this feature between monoraphid diatoms. Gogorevia and Lemnicola are phylogenetically close genera, and we can postulate that the stauros arose once in this group.
Table
Table 1. Comparison of Platesiberia gen. nov. with Platessa and related monoraphid genera.
Table 1. Comparison of Platesiberia gen. nov. with Platessa and related monoraphid genera.
Platesiberia gen. nov.PlatessaPlatebaikaliaGogorevia
Type speciesP. rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov.P. bavarica Lange-Bertalot & Hofmann 2004P. elegans Kulikovskiy, Glushchenko & Kociolek G. renatii Kulikovskiy, Glushchenko, Maltsev & Kociolek
Striae in RVbiseriatebiseriatemultiseriateuniseriate
Striae in RLVuniseriatebiseriatebiseriateuniseriate
Interstriae in RV externallyflat, the same width as striaeflat, equal or broader than striaeflat, more narrow than striaeflat, broader than striae
Interstriae in RV internallyvery prominent on striae, the same width as striaeflat, equal or broader than striaevery prominent on striae, more narrow than striaeprominent, broader than striae
Interstriae in RLV externallyflat, the same width as striaeflat, equal to or broader than striaeflat, equal to or narrower than striaeflat, broader than striae
Interstriae in RLV internallyvery prominent on striae, the same width as striaeflat, equal to or broader than striaevery prominent, more narrow than striaeprominent, broader than striae
Pore occlusions silica membranehymenessilica membranehymenes
Distal raphe ends externallytear-shaped, extending slightly onto valve mantle; turned in opposite directionslinear and straight on valve facetear-shaped, straight on valve facedeflected to opposite sides, terminating in drop-like pores on the valve face
Distal raphe ends internallyin small helictoglossae; curved in the opposite directionsin small helictoglossae; curved in the opposite directionsin small helictoglossa; straightin small helictoglossae; turned in different directions
Central raphe ends externallytear-shaped, straighttear-shaped, straighttear-shaped, straighttear-shaped, straight
Central raphe ends internallylinear, straight, slightly curved in opposite directionsstraight; turned in opposite directionslinear, straight, slightly curved in opposite directionsslightly curved in opposite directions
Axial area in RV, externallyflat, narrow and linearflat, narrow and linearnarrow and linear, slightly widened into central area, sternum detectedvery narrow, linear, opening rather abruptly to the central area
Axial area in RV, internallyenough broad and widened to central area, sternum evident and elevatedflat, narrow and linearnarrow and linear, slightly widened to central area, sternumslightly raised above the surface of the striae
Axial area in RLV, externallynarrow and linear, slightly widened to central areavery broad, flatnarrow and linear, slightly widened to central area, sternum, deep on valve faceflat, narrow sternum is evident
Axial area in RLV, internallybroad rhombic sternumvery broad, flatwide lanceolate, sternum-like prominent on the striae levelflat, narrow sternum is evident
Central area in RV externallybowtie-shaped, narrow, slightly raisedsmall, circularflat, moderately transapically enlargedmore or less symmetrical, narrow, rectangular to wedge-shaped fascia reaching in some species the valve margins
Central area in RV internallynarrow, bowtie-shaped due to shorter two or three striae, elevated, stauros-likesmall, circularprominent, moderately transapically enlargedforming a raised stauros
Central area in RLV externallysmall, flatabsent due to broad axial areaflat, transapically enlargedasymmetrical, narrow, wedge-shaped fascia reaching in some species the valve margins
Central area in RLV internallysmallabsent due to broad axial areaprominent, transapically enlargedmore or less expressed, asymmetrical, wedge-shaped
ReferencesThis investigation, [8][37,46][8,9][10]
Table
Table 2. Comparison of Platesiberia gen. nov. with some monoraphid genera.
Table 2. Comparison of Platesiberia gen. nov. with some monoraphid genera.
Platesiberia gen. nov.GololoboviaAchnanthidiumSkabitschewskiaGliwicziaLemnicola
Type speciesP. rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov.G. mariae Kulikovskiy, Glushchenko, Genkal & Kociolek sp. nov.A. microcephalum Kützing 1844S. dispersipunctata Kulikovskiy & Lange-Bertalot 2015G. tenuis Kulikovskiy, Lange-Bertalot & Witkowski 2013L. hungarica (Grunow) Round & Basson 1997
Striae in RVbiseriateuniseriateuniseriateuniseriateuniseriatebiseriate
Striae in RLVuniseriateuniseriateuniseriatebiseriateuniseriatebiseriate
Interstriae in RV externallyflat, the same width as striaeflat, equal to striaeflat, equal or broader than striaeflat, equal to striaeflat, slightly broader than striaeflat, wider than striae
Interstriae in RV internallyvery prominent on striae, the same width as striaeflat, equal to striaeflat, equal or broader than striaeProminent, equal to or broader than striaeslightly prominent, slightly broader than striaeslightly raised, narrower than striae
Interstriae in RLV externallyflat, the same width as striaeflat, equal to striaeflat, equal to or broader than striaeprominent, equal to or broader than striaeflat, equal to or broader than striaeflat and broader than striae
Interstriae in RLV internallyvery prominent on striae, the same width as striaeflat, equal to striaeflat, equal to or broader than striaevery prominent (rib-like), connected with sternum, close areolae by silica layer (alveoli), narrower than striae; in some species with reduced striae the interstriae are longer and broaderslightly raised, narrower than striaeevidently raised, narrower than striae
Pore occlusions silica membranehymeneshymenessilica membranesilica membrane, below the occlusion a pair of foramina lipshymenes
Distal raphe ends externallytear-shaped, extending slightly onto valve mantle; turned in opposite directionscurved, terminate to opposite sides of the apices, extending onto valve mantlestraight or slightly curved on valve face or extending slightly going onto valve mantle; turned to the same directionstraight or slightly curved on valve face or extending slightly onto valve mantle; turned in opposite directionsstraight and extending slightly onto mantle, slightly deflected in opposite directionsextending onto mantle; curved in opposite directions
Distal raphe ends internallyin small helictoglossae; curved in the opposite directionsin small helictoglossae; turned in different directionsin small helictoglossae; turned in different directionsin small helictoglossae; turned in different directionshelictoglossae almost undeveloped; slightly turned in opposite directionsin small helictoglossae; slightly curved in opposite directions
Central raphe ends externallytear-shaped, straighttear-shaped, slightly curved to the same directionslim or tear-shaped, straight or slightly curved to the same direction tear-shaped, straighttear-shaped, straightstraight and curved to the same direction
Central raphe ends internallylinear, straight, slightly curved in opposite directionslinear; tear-shaped, slightly curved in opposite directionsstraight or in small hook; turned to the different directionstraight; turned to the different directionstraight; evidently turned in different directionsstraight; slightly curved in opposite directions
Axial area in RV, externallyflat, narrow and linearnarrow and linear, sternum detectednarrow and linear or widened to form central areanarrow and linear, sternum detectednarrow and linear, sternum detectedlinear, narrow, sternum evident
Axial area in RV, internallyenough broad and widened to central area, sternum evident and elevatednarrow and linear or widened to central area, sternum evidentnarrow and linear or widened to central area, sternum evidentsternum well-developed, narrow and linearsternum well-developed, narrow and linearlinear, narrow, in well-developed sternum
Axial area in RLV, externallynarrow and linear, slightly widened to central areanarrow and linear, deep on valve facenarrow and linear or slightly wider to central areanarrow and linear or slightly wider to central area, in many species deep on valve facenarrow and wider to central area, almost rhombicflat, linear
Axial area in RLV, internallybroad rhombic sternumhas the axial rib elevated near the unequal central area onlynarrow and linear or slightly wider to central areanarrow lanceolate, raised on valve face in middlebroad rhombic sternumlinear, well-developed sternum
Central area in RV externallybowtie-shaped, narrow, slightly raisedunequal in width, with the widest side extending to the margin and having no short striae, the opposite, narrower side with short striae evident at the marginabsent or present by fascia, flatcircle or bowtie-shaped, flat or slightly raised in centerstauros elevated, central nodule evidently raisedstauros
Central area in RV internallynarrow, bowtie-shaped due to shorter two or three striae, elevated, stauros-likethickened, is unornamented but not a staurosabsent or present by fascia slightly raised on valve facecircle or bowtie-shaped, raised in centerstauros strongly elevated with cavum on one sidestauros
Central area in RLV externallysmall, flatunequal in width, with the widest side extending to the margin and having no short striae, the opposite, narrower side with short striae evident at the marginabsent or present by fascia, flatflat, fascia in one cavum side of valve stauros elevatedslightly circle or not evident
Central area in RLV internallysmalldistinct, thickened, unequalabsent or present by fascia, flatcavumstauros strongly elevated with cavum on one sideslightly circular or not evident
ReferencesThis investigation, [8][11][47,48,49,50][8][8], own data[51,52]
Areolae are closed internally in our new genus Platesiberia gen. nov. by silica cover. Mostly, areolae are covered by hymenes as pore occlusions. SEM did not allow us to observe pore occlusions with hymenes. Hymenes as morphological feature are characterized by a slim silica plate with many tiny pores that are differently shaped [53]. In Gliwiczia, pore occlusions are presented additionally by a pair of foramina lips below the silica membranes [8].
We discussed differences of pore occlusion between monoraphid genera when we described the genus Gololobovia [11]. We referred to Shi et al. [52] who indicated ‘convex hymenes’ and show them to be present in Lemnicola and in our investigation for Gololobovia. This structure covers every areola internally and is found in Lemnicola, Gogorevia and Gololobovia. Further investigation will be important for understanding these peculiarities and needs the combination of morphological analysis with transmission electron microscopy, scanning microscopy with high magnification and molecular phylogenetic investigations. We note here the importance of this work for the future.
We acknowledge here that this work is based on valve morphological features only, and some of these features are only evident with scanning electron microscopy. More recent studies on the delineation and description of taxa take what has been termed a “polyphasic” approach, utilizing a variety of features, morphological and molecular, to characterize new taxa (e.g., [31,54]). Of course, having a broader understanding of a wider range of features to better understand a taxon, and its phylogenetic relationships, is a highly desirable goal. Due to timing of collections and whether the taxon is extant or extinct help define what can be known at any one time. We also do not have in place yet a formal analysis of relationships and whether each of these freshwater monoraphid genera are monophyletic [55]. Formal phylogenetic analyses of some monoraphid diatom genera have affirmed, however, that morphologically diagnosable groups of monoraphid diatoms are monophyletic (e.g., [10]). Further research is necessary to more fully understand the taxon described herein and to assess its systematic position among the freshwater monoraphid diatoms.
This investigation increases our understanding of the diversity of monoraphid freshwater genera that were previously assigned to the old catch-all genus Achnanthes Bory. Description of new genera is related to our investigation of morphology from different monoraphid taxa and combining morphological features together with molecular data for some genera where possible. This work is based on a larger investigation of biodiversity from different poorly studied areas or hotspots of diatoms. Lake Baikal is a unique place, existing for 25–30 million years [56], thus allowing a long time for the evolution of diatoms and resulting in very high species diversity. We believe that diversity of monoraphid diatoms in this ancient lake will be investigated in the future more carefully and many new species and possibly new genera will be described. Our previous investigation of monoraphid diatoms [8,36] from Lake Baikal showed very high diversity between monoraphid and biraphid genera with interesting and shared unusual morphology. It is important for us to combine new morphological information about freshwater diatoms not only from Lake Baikal but also from Southeast Asia, Australia, Africa and South America. These areas have also been poorly studied up till now.

Author Contributions

Conceptualization, M.S.K.; methodology, A.M.G. and M.S.K.; validation, A.M.G., M.S.K. and J.P.K.; investigation, A.M.G., M.S.K. and J.P.K.; resources, M.S.K.; writing—original draft preparation, A.M.G. and M.S.K.; writing—review and editing, A.M.G., M.S.K. and J.P.K.; visualization, M.S.K., I.V.K., S.I.G. and A.M.G.; supervision, M.S.K.; funding acquisition, M.S.K. All authors have read and agreed to the published version of the manuscript.

Funding

Publication is based on research carried out with financial support by Russian Science Foundation (19-14-00320Π) for LM and SEM and by framework of state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme 122042700045-3) for finishing manuscript.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

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Figure 1. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Slide no. 15645m. Light microscopy, differential interference contrast, size diminution series. (A–H). Raphe valves. (I–P). Rapheless valves. Scale bar = 10 μm.
Figure 1. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Slide no. 15645m. Light microscopy, differential interference contrast, size diminution series. (A–H). Raphe valves. (I–P). Rapheless valves. Scale bar = 10 μm.
Water 14 02957 g001
Water 14 02957 g002 550
Figure 2. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Scanning electron microscopy. Raphe valves. (A). The whole valve, external view. (B–E). Entire valve, internal views. (F). Central area, internal views. (G,H). Valve ends, internal views. Scale bar (A–C) = 5 μm; (D,E) = 2 μm; (F–H) = 1 μm.
Figure 2. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Scanning electron microscopy. Raphe valves. (A). The whole valve, external view. (B–E). Entire valve, internal views. (F). Central area, internal views. (G,H). Valve ends, internal views. Scale bar (A–C) = 5 μm; (D,E) = 2 μm; (F–H) = 1 μm.
Water 14 02957 g002
Water 14 02957 g003 550
Figure 3. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Scanning electron microscopy. Rapheless valves, internal views. Scale bar (A,B,F,H) = 5 μm; (C–E,G) = 2 μm.
Figure 3. Platesiberia rhombicolanceolata (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Scanning electron microscopy. Rapheless valves, internal views. Scale bar (A,B,F,H) = 5 μm; (C–E,G) = 2 μm.
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Figure 4. Platesiberia baicalensis (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Slide no. 15651m. (A–H). Light microscopy, differential interference contrast, size diminution series. (I,J). Scanning electron microscopy. (A–D,I). Raphe valves. (E–H,J). Rapheless valves. Scale bar (A–H) = 10 μm; (J) = 5 μm; (I) = 3 μm.
Figure 4. Platesiberia baicalensis (Kulikovskiy & Lange-Bertalot) Kulikovskiy, Glushchenko, Genkal & Kociolek comb. nov. Slide no. 15651m. (A–H). Light microscopy, differential interference contrast, size diminution series. (I,J). Scanning electron microscopy. (A–D,I). Raphe valves. (E–H,J). Rapheless valves. Scale bar (A–H) = 10 μm; (J) = 5 μm; (I) = 3 μm.
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Kulikovskiy, M.S.; Glushchenko, A.M.; Genkal, S.I.; Kuznetsova, I.V.; Kociolek, J.P. Revision of Monoraphid Diatom Genus Platessa with Description of Platesiberia gen. nov. from Ancient Lake Baikal. Water 2022, 14, 2957. https://doi.org/10.3390/w14192957

AMA Style

Kulikovskiy MS, Glushchenko AM, Genkal SI, Kuznetsova IV, Kociolek JP. Revision of Monoraphid Diatom Genus Platessa with Description of Platesiberia gen. nov. from Ancient Lake Baikal. Water. 2022; 14(19):2957. https://doi.org/10.3390/w14192957

Chicago/Turabian Style

Kulikovskiy, Maxim S., Anton M. Glushchenko, Sergei I. Genkal, Irina V. Kuznetsova, and John Patrick Kociolek. 2022. "Revision of Monoraphid Diatom Genus Platessa with Description of Platesiberia gen. nov. from Ancient Lake Baikal" Water 14, no. 19: 2957. https://doi.org/10.3390/w14192957

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