Zlatko Levkov

Saints Cyril and Methodius University of Skopje · Faculty of Natural Sciences and Mathematics

Given the limited understanding of species diversity and ecological preferences of diatoms of the genus Navicula in spring ecosystems, herein we present and describe as species new to science, Navicula aquaesuavis Lange-Bert., Levkov, Cid-Rodríguez, A.A.Saber and Cantonati sp. nov. This species was collected from a mountain spring located above the...

Diversity of Halamphora (Diatomae)

In 2020, North Macedonia conducted the first national assessment of ecosystem condition. The assessment fully adhered to MAES (Mapping and Assessment of Ecosystems and their Services) working group guidelines and represents the first implementation study in North Macedonia, marking it as the first Southeastern European country outside the EU to con...

The research presented investigates whether DNA-based metabarcoding can replace the morphology-based identification of diatom taxa in the ecological status assessments of aquatic habitats. When comparing data obtained with microscopy and metabarcoding, significant deviations have been noticed. One of the main reasons includes the incompleteness of...

Adlafia is a relatively small diatom genus in terms of number of species and consisting of small-celled species with delicate morphology that is barely visible under the light microscope. Only a few morphological characteristics recognizable under a light microscope can be used to identify species. This could lead to a broader species concept and m...

Diploneis zhui sp. nov. was observed in epilitic diatom communities from Jiuzhaigou National Nature Reserve. The species is described herein based on light microscopy (LM) and scanning electron microscopy (SEM) and ecological information of the type locality is provided. The species is characterized by linear to linear-elliptic valves with broadly...

A new species Sellaphora jiuzhaienis sp. nov. was found in epilithic samples from Jiuzhaigou National Nature Reserve, China. The species is described herein as new to science based on light microscopy (LM) and scanning electron microscopy (SEM), and ecological information is provided. The species has linear to linear-elliptic valves, 17.5–33.5 μm l...

Rhoicosphenia is a relatively small diatom genus regarding the number of species and the genus is characterized by its wedge-shaped frustule and heterovalvar structure. It is one of the few genera that is distributed in both marine and freshwater habitats. Few species of Rhoicosphenia are known along the stretched Baltic Sea coast of Sweden. The pr...

Diatom species identification with DNA metabarcoding is an economical, fast and reliable alternative to identification via light microscopy for river quality monitoring. Using a short DNA sequence of the rbcL gene and 'Diat.barcode', a reference barcode library, enables the identification of more than 90% of the environmental sequences to species l...

Climate has strongly influenced species composition and evolution over geological and contemporary timescales. While most attention has been paid to the relationship between macroevolutionary processes and climate along latitudinal gradients, very little is known about how climate changes affect the microevolutionary mechanisms of macroevolutionary...

Combining morphological and molecular approaches, a new diatom species is described in the genus Mayamaea from a Special Nature Reserve, Okanj bara in Serbia, an alkaline and subsaline soda pan with pronounced seasonal drying. Mayamaea pannonica sp. nov. possesses typical characteristics of the genus Mayamaea, such as uniseriate striae and hymenes...

The historic type material of Microneis gracillima, Navicula pyrenaica, Achnanthes amphicephala, Achnanthes thienemannii and Achnanthidium rostropyrenaicum was investigated together with additional European populations of these species using light and scanning electron microscopy. The morphology of the species was compared to similar taxa. Achnanth...

A new freshwater fossil diatom taxon Rimocostatus bugojnicus gen. et sp. nov, from Miocene sediments at the Gračanica site, Bugojno palaeolake in Bosnia and Herzegovina, is described. The main morphological feature of the genus is the presence of marginal rimoportulae with simple, round external openings positioned on interfascicles on the valve ma...

Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584‐m‐long D...

Alpine ponds are known biodiversity hot-spots and refugia for many rare and endangered species. They are also considered to be vulnerable habitats in terms of acidification, eutrophication, modification and climatic changes. Recently, a detailed study of diatoms in these habitats in North Macedonia has been started to evaluate their status and thre...

During a survey of diatoms in the artificial sandpit lake “Peskara” in the protected zone of the Rusanda Nature Park, a large number of brackish taxa at epipsamic and epiphytic communities were recorded (e.g. Bacillaria paxillifera, Caloneis permagna, Ctenophora pulchella, Entomoneis costata. Haslea duerrenbergiana, Navicula salinarum, Nitzschia ag...

The Quaternary is characterized by a series of glacial-interglacial cycles and a shift in the Earth's climate state known as the mid-Pleistocene Transition (MPT, ca. 1200 ka to 720 ka). The progressive increase in glacial cycle length from approximately 41 ka to on average 100 ka affected marine and terrestrial life, but how it affected freshwater...

Karst ecosystems play a unique role as exceptional natural habitats in sustaining biodiversity. This study focuses on diatoms, a diverse group of microeukaryotes in the periphytic community of a karstic river. In a multi-microhabitat study along the Krka River (Croatia), our goal was to obtain a detailed overview of diatom diversity and community s...

Aim: Ecological communities are structured through the interplay of deterministic assembly processes such as competition and environmental filtering. Whereas the drivers of spatial community structure are frequently studied in extant communities, little is known about the relative importance of assembly processes in response to environmental factor...

The Krka River is located at Balkan Peninsula in the Dinaric region of Croatia and it is a typical groundwater-fed karst river characterized by an unusual phenomenon-tufa. Tufa designates porous CaCO3 deposits forming under specific physical and chemical conditions and hosting very diverse freshwater biota. Karst springs are considered one of the m...

Lake Ohrid hosts a highly diverse contemporary diatom fl ora with more than 800 recorded diatom species. Many are considered endemic to the lake, or are shared endemics with its sister Lake Prespa. Diverse diatom assemblages were also observed in the fossil record preserved in the DEEP-5045-1 core that resulted in the description of a few new and p...

In a response to changes in the environment, species can adapt to the conditions by changing their phenotype, physiology and/or behaviour. This can also be expected in diatoms, particularly in planktonic species, because of their short generation times and high sensitivity to environmental changes. Sediments from ancient lakes dating back several m...

During a biomonitoring assignment in the Swiss canton Ticino, an unknown Fragilaria taxon was discovered that could not be identified using the currently available literature. The results of a morphological comparison with the type material of F. recapitellata, based on light and scanning electron microscopy, showed that the new Swiss taxon has suf...

Freshwater species are particularly sensitive to climate fluctuations, but little is known of their response to the large-scale environmental change that took place during the Quaternary. This is partly due to the scarcity of continuously preserved freshwater sedimentary records with orbital chronology. We use a 1.363 Ma high-resolution fossil reco...

Lowland intermittent ponds, although biologically important, are poorly studied water habitats. During the analyses of the material taken from lowland pond in Pelagonia Valley, and Vitachevo, Republic of North Macedonia, the diatom Sellaphora pelagonica sp. nov. was recorded and described based on light and scanning electron microscopy. The species...

This is the first detailed taxonomic study of the genus Navicula in the Krasnodar Territory of the Caucasus region, Russia. During the study of the genus in waterbodies of the Adegoy River valley 15 taxa were recorded. Two species, N. adegoyensis sp. nov. and N. pseudocryptofallax sp. nov., are described as new to science. Their morphology is studi...

The Balkan Peninsula is a biodiversity hotspot and hosts numerous mountain lakes, which offer a refuge for a multitude of species. However, previous pristine habitats have been deeply affected by anthropogenic change, such as non-native fish introductions, which calls for multi-species considerations in the last remaining unaltered habitats. We car...

The scarcity of high-resolution empirical data directly tracking diversity over time limits our understanding of speciation and extinction dynamics and the drivers of rate changes. Here, we analyze a continuous species-level fossil record of endemic diatoms from ancient Lake Ohrid, along with environmental and climate indicator time series since la...

In the light of ever-growing issue of climate changes, a special focus has been directed towards freshwater periphytic algal communities. Diatoms, a commonly dominant group of protists in periphytic assemblages, are frequently used for ecological water-quality assessments of rivers. Diatom-based indices for ecological status assessment are based on...

Evidence for global environmental and climate change-related loss of biodiversity is accumulating. Understanding the causes of species community change is thus essential for effective management and conservation policies. Nonetheless, disentangling the relative influence of the individual or multiple drivers determining the species communities is c...

A new fossil diatom species, Tertiarius minutulus sp. nov., is described from a sediment sequence DEEP-5045-1 of Lake Ohrid. The species is characterized by small valves (3.0–8.0 µm) with a round shape, a marginal area with radially arranged costae and a central uneven area with scattered areolae. Externally, the alveoli are occluded by cribra perf...

A new species, Envekadea vranaensis Caput Mihalić, Galović & Levkov sp. nov., is described from Holocene sediments of Lake Vrana, Croatia. The new species is characterized by linear-lanceolate valves with broadly capitate apices and is 40.0–67.5 μm long and 7.5–9.0 μm wide. Based on its morphological features it is similar to E. hedin...

A new freshwater diatom species Pinnularia baetica sp. nov. is described from two different ponds from the Mediterranean area: Andalucia (South of Spain) and Lake Livadičko, Serbia. The species is described by observations under light (LM) and scanning electron microscopy (SEM). The most similar taxa to P. baetica are P. atlasii and P. infirma that...

In this overview (introductory article to a special issue including 14 papers), we consider all main types of natural and artificial inland freshwater habitas (fwh). For each type, we identify the main biodiversity patterns and ecological features, human impacts on the system and environmental issues, and discuss ways to use this information to imp...

Mediterranean climates are characterized by strong seasonal contrasts between dry summers and wet winters. Changes in winter rainfall are critical for regional socioeconomic development, but are difficult to simulate accurately¹ and reconstruct on Quaternary timescales. This is partly because regional hydroclimate records that cover multiple glacia...

Background and aims – An increased interest in the diatom flora from subaerial habitats in the Republic of North Macedonia has revealed the presence of a large number of interesting and often unknown, species. During a recent biodiversity survey, seven Muelleria species were recorded, several of which could not be identified based on the available...

Background and aims – The detailed analysis of algae and cyanoprokaryotes in a heterogeneous group of spring habitats (including all the different typologies) of the northern Apennines (Emilia-Romagna Region, Italy) revealed a new Amphora species in a small mountain flowing spring with low conductivity, and a new Halamphora species in a large, inla...

During a survey of freshwater diatoms from a mountain lake, Lake Congqiancuo, Haizishan Nature Reserve, Yading, Daocheng County, Sichuan Province, China, a new Halamphora species, Halamphora daochengensis sp. nov. was found. A detailed morphological description of the new species is presented, based on light and scanning electron microscopy. The ma...

Morphological asymmetry in raphid pennate diatoms is detectable not only by valve outline and specific frustule features, but also in their ontogeny. All raphid pennate diatoms exhibit cryptic lateral polarity, which is associated with the asymmetric formation of the valve sides along the apical axis. Differences in the relative widths of primary a...

The genus Neidiopsis is small comprising eight known taxa distributed in oligotrophic to dystrophic freshwater habitats. During observations of diatoms from alpine intermittent ponds on the Shara Mountain, Republic of North Macedonia, a species of Neidiopsis with high abundance was observed. It is characterized by linear to linear–lanceolate valves...

The genus Amphora sensu lato was considered highly heterogeneous for a long time. Modern microscopy and molecular analyses revealed significant differences in cell morphology and structure, thus suggesting polyphyly of the genus. New findings resulted in separation and description of several amphoroid genera. Recently, the genus Tetramphora Meresch...

Intraspecific morphological variation in Cyclotella cavitata from Lake Ohrid

Intraspecific morphological variation in Cyclotella cavitata from Lake Ohrid

Achnanthes boyei Østrup (1918: 41, pl. 4: fig. 60) was described based on a sample collected in 1914 from a small spring in Hallormsstaðaskógur National Forest in Iceland and named for J. Boye Petersen who collected the sample. The species was characterized (translated from the Latin description) by ‘a narrowly lanceolate, weakly asymmetrical valve...

During the first study of the diverse diatom assemblages in Rara Lake, the largest lake in Nepal, 11 species of Gomphonema, belonging to six morphological groups, and Gomphoneis qii could be investigated using light and scanning electron microscopy. Five new Gomphonema species are described: Gomphonema subodhii, Gomphonema parasundaense, Gomphonema...

The extraordinary diversity in long-lived lakes is largely driven by distinct eco-evolutionary processes. With their unique biota and numerous endemic taxa, these lakes are key settings for fundamental studies related to ecology, diversity, and evolution. Here, we test how the environment shapes diatom diversity and community patterns over space in...

Due to the ubiquity and high dispersal capacity of unicellular eukaryotes, their often extraordinary diversity found in isolated and long‐lived ecosystems such as ancient lakes is typically attributed to multiple colonization events rather than to in situ speciation. However, respective evolutionary studies are very scarce and the often high number...

The interplay of deterministic processes such as environmental filtering or species competition and stochastic processes like dispersal or extinction govern community patterns in time and space. However, empirical evidence from nature about the relative contributions of these processes and their drivers in time is limited. This may be partly due to...

What determines species diversity and can ecosystems reach equilibrial species richness? Previous contributions to these puzzling questions came mainly from simulation studies or global analyses with heterogeneous geological, environmental and paleontological records. These deficiencies call for evolutionary studies in model systems with continuous...

Diatom diversity - progress and current knowledge

Four new species are described in the genus Odontidium from the Himalaya in Nepal, and the Garhwal and Kumaon regions in India using light and electron microscopy. We compare the Himalayan taxa to recently described species from the European Alps and Macedonia. In addition we illustrate some specimens of Diatoma rupestris, a species recently descri...

Diatoms are unicellular, photosynthetic, eukaryotic organisms often classified as among the algae. There are around 15 000 known species, but many more have yet to be described. Their uniqueness lies in the siliceous covering of the cell, each being encased in a pair of silica valves. Silica is virtually inert and indestructible, so after the organ...

This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismote...

The species of the genus Craticula are widely distributed in Europe, mostly occurring in brackish, saline to heavi-ly polluted waters. Some of the species are considered as being most tolerant to pollution. Recently, detailed observa-tions of this genus in Macedonia have been performed. During this study, 15 taxa have been recorded. One of the spec...

This paper addresses the typification of two Navicula Bory species described by H.P. Gandhi along with a transfer to the ge-nus Luticola D.G.Mann. The species described are Luticola jogensis comb. nov., stat. nov. and Luticola gandhii comb. nov., nom. nov., stat. nov. Both species were encountered in similar aerophilic habitats from the Western Gha...

The species of the genus Craticula are widely distributed in Europe, mostly occurring in brackish, saline to heavi-ly polluted waters. Some of the species are considered as being most tolerant to pollution. Recently, detailed observa-tions of this genus in Macedonia have been performed. During this study, 15 taxa have been recorded. One of the spec...

Ancient Lake Ohrid, the oldest extant European lake, harbors an extraordinary endemic richness in various groups of organisms. However, age and origin for most of its endemic lineages remain largely unknown. A recent molecular phylogeny of the largest gastropod species flock from Lake Ohrid suggested an intra-lacustrine origin for most of its taxa....

Lake Ohrid is the oldest existing lake in Europe and it is known for its high diversity with around 200 endemic or relict diatom species recognized. In order to understand this phenomenon, a large project on deep drilling was performed and a core with maximum sediment depth of 569 m which spans > 1.2 million years was recovered. Two new species of...

Mastogloia is one of the few species-rich diatom genera the majority of whose taxa inhabit the marine environment with only a small number of taxa in freshwater habitats. An ongoing revision of the Macedonian diatom flora, mainly over the last decade, has revealed many previously misidentified taxa. Currently, seven freshwater Mastogloia taxa have...

Lake Ohrid on the Balkan Peninsula is one of the very few lakes in the world that provides a continuous and high-resolution record of environmental change of >1.2 Ma. The outstanding number of endemic taxa (>300 endemic taxa) in Lake Ohrid in combination with its long existence makes Lake Ohrid a unique target to study the drivers of speciation and...

A new diatom genus, Cribrionella gen. nov., is described from Quaternary sediments of Lake Ohrid. Cribrionella comprises distinct morphological features, such as: i) presence of submarginal alveoli followed by regularly or irregularly arranged areolae, ii) cribra on external areolar openings, iii) absence of silicate layers on internal areolar open...