On the morphological variability of Navicula schmassmannii (Bacillariophyta)

2010 ◽  
Vol 44 ◽  
pp. 32-38 ◽  
Author(s):  
S. I. Genkal ◽  
W. G. Kharitonov
Keyword(s):  
Morphological Variability ◽  
Central Area ◽  
Diatom Species ◽  
Species Diagnosis ◽  
Wide Variability ◽  
Ultraoligotrophic Lake

On the basis of the studied materials from the ultraoligotrophic lake Elgygytgyn (Chukotka), a rare for the flora of Russia diatom species Navicula schmassmannii was recorded. In the studied populations of the species a wide variability of morphological quantitative (valve length and width, the number of stria in 10 μm) and qualitative (the shape of the valve and the central area) features was marked. It made the basis for emending of the species diagnosis.

New species of benthic marine diatoms (Bacillariophyta) from the Western Pacific islands of Guam and Yap

Phytotaxa ◽  
2021 ◽  
Vol 508 (3) ◽  
Author(s):  
CHRISTOPHER S. LOBBAN
Keyword(s):  
Pacific Islands ◽  
Central Area ◽  
Marshall Islands ◽  
Marine Diatom ◽  
Large Species ◽  
Diatom Species ◽  
Cell Interior ◽  
Pennate Diatom ◽  
The Western Pacific ◽  
Benthic Marine Diatoms

In the course of preparation of a major checklist for Yap and ongoing investigations into the benthic marine diatom flora of Micronesia, thirteen new araphid and raphid pennate diatom species have been recognized and are described here. Plagiogramma subatomus is even smaller than P. atomus and the pseudoseptum forms a box with only a small opening toward the cell interior. Licmophora romuli is similar in size and spathulate shape to L. remulus, but the majority of the striae in the lamina lack vimines. L. graphis is exceedingly delicate, pencil-shaped, with apical striae 60–70 in 10 µm. Divergita biformis and D. decipiens are straight species with striae biseriate on the margin, uniseriate on the valve face, differing in the shape and prominence of the sternum and the shape of the valve-face areolae. D. macinnisii (from Marshall Islands, but included here for comparison) is curved, again with the decussate areolar pattern on the mantle, but with single extended areolae along each side of the linear sternum. These characters slightly amend the diagnosis of the genus.  Thalassionema baculum is a very short member of the genus, linear and isopolar. Climaconeis tarangensis is curved and differs from C. riddleae in stria density and areola shape; C. minaegensis is straight, without a stauros or craticular bars, of intermediate length, 228–247 µm. First SEM observations of Climaconeis lorenzii are presented and an updated key to Climaconeis is appended. Parlibellus paschalis is a tube-dwelling species differing from P. delognei is lacking cuniculi and pores in the central area. P. waabensis is a relatively large species, possibly tube-dwelling, that differs from P. delognei in shape and spacing of central striae and from P. berkeleyi in width and stria density. Pleurosigma simulacrum differs in ultrastructural details from P. intermedium. Lastly, Nitzschia tarangensis is a conopeate species, spathulate in profile with ribs along the edge of the valve depression and bordering the raphe, and with pores in the peri-raphe zone.

A new species of Neidiomorpha (Bacillariophyceae) from Dianshan Lake in Shanghai, China

Phytotaxa ◽  
2019 ◽  
Vol 423 (2) ◽  
pp. 99-104
Author(s):  
FEN LUO ◽  
QI YANG ◽  
KAIJUAN GUO ◽  
TENGTENG LIU ◽  
QUANXI WANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Species ◽  
Central Area ◽  
Diatom Species ◽  
Dianshan Lake ◽  
A New Species ◽  
Scanning Electron

A new diatom species, Neidiomorpha dianshaniana sp. nov., found in Dianshan Lake in Shanghai, China, is described herein. The morphology of N. dianshaniana has been documented by light and scanning electron microscopy. Neidiomorpha dianshaniana valves are elliptical in outline with rostrate apices. Raphe is almost straight and filiform. The axial area is narrow and linear. The central area is small, round to transversely elliptical or irregular. Striae are slightly radiate and almost parallel near the apices. Puncta are arranged in undulating longitudinal rows. Neidiomorpha dianshaniana’s most visible feature is its lack of central constriction, in which respect it differs from the three other species in the genus Neidiomorpha.

Ctenophora sinensis: a new diatom species (Bacillariophyta) from China with comments on its structure, nomenclature and relationships

Phytotaxa ◽  
2020 ◽  
Vol 460 (2) ◽  
pp. 115-128
Author(s):  
BING LIU ◽  
DAVID M. WILLIAMS ◽  
ZHU-XIANG LIU ◽  
JIN-HUA CHEN
Keyword(s):  
Brackish Water ◽  
Central Area ◽  
Diatom Species ◽  
Lake Qinghai ◽  
Vegetative Cells ◽  
Qinghai Province ◽  
Water Lake ◽  
Brackish Water Lake

Lake Qinghai is an ancient brackish water lake in the Qinghai province of China. A number of endemic diatom species have already been discovered and described from the lake. This study describes another new endemic diatom species: Ctenophora sinensis sp. nov. Ctenophora sinensis has the following features: (1) frustule and valve are lanceolate; (2) the central area is slightly buttressed internally; (3) its areolae have both outside sieve-like closing plates and inside hymenate occlusions; (4) an apical hyaline field exists near each rimoportula; (5) a pseudoseptum is always presents at each pole; and (6) the cingulum has a 4:2 configuration of girdle bands in normal vegetative cells. Some remarks are provided on the nomenclature of Ctenophora and a few comments on the relationships of the genus.

scholarly journals The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate

2010 ◽  
Vol 7 (3) ◽  
pp. 4689-4714 ◽  
Author(s):  
J. M. Reed ◽  
A. Cvetkoska ◽  
Z. Levkov ◽  
H. Vogel ◽  
B. Wagner
Keyword(s):  
Morphological Variability ◽  
Central Area ◽  
Early Holocene ◽  
Future Research ◽  
Lake Basin ◽  
Last Interglacial ◽  
Lake Ohrid ◽  
Concentration Data ◽  
Last Glacial ◽  
The Last Glacial

Abstract. Lake Ohrid is a site of global importance for palaeoclimate research. This study presents results of diatom analysis of a ca. 136 ka sequence, Co1202, from the northeast of the lake basin. It offers the opportunity to test diatom response across two glacial-interglacial transitions and within the Last Glacial, while setting up taxonomic protocols for future research. The results are outstanding in demonstrating the sensitivity of diatoms to climate change, providing proxy evidence for temperature change marked by glacial-interglacial shifts between the dominant planktonic taxa, Cyclotella fottii and C. ocellata, and exact correlation with geochemical proxies to mark the start of the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger evidence in this site for warming during MIS3 than recorded in other productivity-related proxies, peaking at ca. 39 ka, prior to the extreme conditions of the Last Glacial maximum. In the light of the observed patterns, and from the results of analysis of early Holocene sediments from a second core, Lz1120, the lack of a response to Late Glacial and early Holocene warming from ca. 15–7.4 ka suggests the Co1202 sequence may be compromised during this phase. After ca. 7.4 ka, there is evidence for enhanced nutrient enrichment compared to the Last Interglacial, following by a post-Medieval cooling trend. Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In contrast, C. ocellata shows morphological variation in the number of ocelli between interglacials, suggesting climatically-forced variation or evolutionary selection pressure. The application of a simple dissolution index does not track preservation quality very effectively, underlining the importance of diatom concentration data in future studies.

scholarly journals Fragilaria rinoi sp. nov. (Fragilariales, Fragilariophyceae) from periphytic river samples in Central Portugal

2016 ◽  
Author(s):  
Cristina Delgado ◽  
M. Helena Novais ◽  
Saúl Blanco ◽  
Salomé F.P. Almeida
Keyword(s):  
Central Area ◽  
River Basins ◽  
Scanning Electron Micrographs ◽  
Diatom Species ◽  
Alkaline Ph ◽  
Mean Values ◽  
Central Portugal ◽  
Lis River ◽  
Scanning Electron ◽  
Freshwater Diatom

A new benthic freshwater diatom, Fragilaria rinoi Almeida & C.Delgado sp. nov., is described from river periphyton samples in Portugal. Fragilaria rinoi sp. nov. is illustrated and discussed based on populations collected from the Vouga, Mondego and Lis river basins in central Portugal and compared with the type material of Fragilaria vaucheriae (Kütz.) J.B.Petersen. The morphological features of the new diatom species are documented through light and scanning electron micrographs, including a comparative analysis with related species of the genus (F. candidagilae Almeida, C.Delgado, Novais & S.Blanco, F. intermedia Grunow in Van Heurck, F. neointermedia Tuji & D.M.Williams, F. recapitellata Lange-Bert. & Metzeltin, F. perminuta (Grunow) Lange-Bert., F. vaucheriae and F. microvaucheriae C.E.Wetzel & Ector). Fragilaria rinoi sp. nov. is characterized by solitary cells without spines, lanceolate valves with slightly rostrate apices, a narrow, linear axial area, and a large, unilateral central area. Fragilaria rinoi sp. nov. may be confused with F. microvaucheriae in terms of length, striae density and outline, although a morphometric analysis revealed that F. rinoi sp. nov. is significantly wider. Fragilaria rinoi sp. nov. is present in rivers with high dissolved oxygen concentrations, medium to high conductivity, neutral to slightly alkaline pH and high mean values of nitrates and ammonium.

Accommodating trait overlap and individual variability in species diagnosis of Ischnosiphon (Marantaceae)

2020 ◽  
Vol 194 (4) ◽  
pp. 469-479
Author(s):  
María Alejandra Buitrago Aristizábal ◽  
Fernando Oliveira Gouvêa De Figueiredo ◽  
Thiago André
Keyword(s):  
Morphological Variability ◽  
Analytical Framework ◽  
Morphological Characters ◽  
Individual Variability ◽  
Intraspecific Diversity ◽  
Species Diagnosis ◽  
Plant Groups ◽  
Morphological Species ◽  
The Many ◽  
Taxonomic Categories

Abstract Recognition and delimitation of taxonomic categories of biological organisms are still challenging and full of controversy. We used Ischnosiphon as a model to unravel the importance of morphometrics as individual-based variables to disentangle the morphological variability of plant species. Ischnosiphon spp. continue to be problematic for users, taxonomists and ecologists, due mainly to the huge morphological variability, the species criteria and circumscription proposed for many taxa and the many habitat and vegetative macro-morphological characters lacking in most currently available exsiccates. Twenty-three morphometric variables were sampled from 228 individuals, belonging to 22 Ischnosiphon spp. Principal components and discriminant multivariate analyses were used to describe and identify patterns of morphological variation in Ischnosiphon. Individual-landmark assessment analysed with multivariate methods captured morphometric intraspecific diversity and morphological variability in Ischnosiphon spp., along with the continuous variation of important morphological traits. By examining the morphology of Ischnosiphon spp. through individual-landmark assessment, we demonstrate that different morphological species concepts used today in the identification of the species are difficult to apply. We propose a replicable and analytical framework to accommodate individual variability in species diagnosis in morphologically diverse plant groups.

Interesting finding of diatoms of the genus Naviculadicta in Elgygytgyn Lake (Chukotka)

2010 ◽  
Vol 44 ◽  
pp. 22-27
Author(s):  
S. I. Genkal ◽  
W. G. Kharitonov
Keyword(s):  
Morphological Features ◽  
Wide Variability ◽  
Species Descriptions ◽  
Ultraoligotrophic Lake

On the basis of the studied materials from the ultraoligotrophic lake Elgygytgyn (Chukotka), species of diatoms rare and new to the flora of Russia were recorded, Naviculadicta digitulus and N. digituloides. The studied populations of the both species show a wide variability of quantitative morphological features (length and width of the valve, the number of stria and areolae in 10 μm). This made the basis for emending of the species descriptions.

A new species of Genkalia (Bacillariophyta) from mountain lakes within the Sichuan Province of China

Phytotaxa ◽  
2018 ◽  
Vol 372 (3) ◽  
pp. 236 ◽  
Author(s):  
F. LUO ◽  
Q-M. YOU ◽  
Q-X. WANG
Keyword(s):  
Central Area ◽  
High Elevation ◽  
Sichuan Province ◽  
Tibet Plateau ◽  
Diatom Species ◽  
Monsoon Climate ◽  
The Sichuan Basin ◽  
Qinghai Tibet Plateau ◽  
Secondary Side ◽  
A New Species

A new diatom species, Genkalia alpina sp. nov., was identified in high elevation lakes in the Mugecuo Scenic Area within the Sichuan Province of China. The area is located in the northern foot of the Hengduan Mountains between the western edge of the Sichuan Basin and the Qinghai-Tibet Plateau, belongs to the subtropical humid monsoon climate, at an altitude of 2600–3800m, with lake water originating mostly from the melting mountain snow. Light and scanning electron microscopy revealed that G. alpina valves are linear with two undulated margins and apices that are subcapitate in larger specimens, but slightly shorter in smaller specimens. The central area is elliptical, and the external proximal raphe ends are straight, or slightly deflected towards the primary valve side. Terminal raphe fissures are strongly bent towards the secondary side and they extend to mantle. Uniseriate striae continue uninterrupted from the valve face to the mantle. The present study is the first report of Genkalia species in China, and expands the geographical distribution of the genus, as well as the known diatom diversity of China.

scholarly journals The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate

2010 ◽  
Vol 7 (10) ◽  
pp. 3083-3094 ◽  
Author(s):  
J. M. Reed ◽  
A. Cvetkoska ◽  
Z. Levkov ◽  
H. Vogel ◽  
B. Wagner
Keyword(s):  
Morphological Variability ◽  
Central Area ◽  
Late Glacial ◽  
Early Holocene ◽  
Future Research ◽  
Lake Basin ◽  
Last Interglacial ◽  
Lake Ohrid ◽  
Last Glacial ◽  
The Last Glacial

Abstract. Lake Ohrid is a site of global importance for palaeoclimate research. This study presents results of diatom analysis of a ca. 136 ka sequence, Co1202, from the northeast of the lake basin. It offers the opportunity to test diatom response across two glacial-interglacial transitions and within the Last Glacial, while setting up taxonomic protocols for future research. The results are outstanding in demonstrating the sensitivity of diatoms to climate change, providing proxy evidence for temperature change marked by glacial-interglacial shifts between the dominant planktonic taxa, Cyclotella fottii and C. ocellata, and exact correlation with geochemical proxies to mark the start of the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger evidence in this site for warming during MIS3 than recorded in other productivity-related proxies, peaking at ca. 39 ka, prior to the extreme conditions of the Last Glacial maximum. In the light of the observed patterns, and from the results of analysis of early Holocene sediments from a second core, Lz1120, the lack of a response to Late Glacial and early Holocene warming from ca. 14.7–6.9 ka suggests the Co1202 sequence may be compromised during this phase. After ca. 7.4 ka, there is evidence for enhanced nutrient enrichment compared to the Last Interglacial, followed by a post-Medieval loss of diversity which is consistent with cooling, but not definitive. Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In contrast, C. ocellata shows morphological variation in the number of ocelli between interglacials, suggesting climatically-forced variation or evolutionary selection pressure. The application of a simple dissolution index does not track preservation quality very effectively, underlining the importance of diatom accumulation data in future studies.

Valve morphology of three species of Neidiomorpha (Bacillariophyceae) from Zoigê Wetland, China, including description of Neidiomorpha sichuaniana nov. sp.

Phytotaxa ◽  
2014 ◽  
Vol 166 (2) ◽  
pp. 123 ◽  
Author(s):  
QI LIU ◽  
J. P. KOCIOLEK ◽  
QUANXI WANG ◽  
CHENGXIN FU
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Central Area ◽  
Systematic Position ◽  
Diatom Species ◽  
Valve Morphology ◽  
Zoige Wetland ◽  
Scanning Electron

A new diatom species, Neidiomorpha sichuaniana sp. nov., is described from Zoigê Wetland, China. The morphology of N. sichuaniana is documented by light and scanning electron microscope and discussed in detail, including a comparison with the two other species in the genus Neidiomorpha also found in Zoigê. Neidiomorpha sichuaniana has a smaller central area and smaller central constriction than N. binodiformis and less apiculate ends than N. binodis. We comment on the systematic position of Neidiomorpha based on the morphology of these three species.

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