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Three new species of Gomphonema Ehrenberg (Bacillariophyta), from Eastern Himalayas, with a note on the unique girdle band structure
Abstract
Three new diatom taxa belonging to the genus Gomphonema were recorded during a survey
of streams of the Eastern Himalayas from the state of Arunachal Pradesh, India. Detailed light (LM) and scanning electron microscope (SEM) observations are used to characterize the morphology and ultrastructure of the three new Gomphonema taxa. Comparisons are made with similar taxa and characters delimiting these new species. All three new taxa have three different kinds of external areolar patterns, confirming the presence of three different groups of Gomphonema in one habitat. Further, one of the species showed a unique fimbriate structure in head pole region of the girdle band. This is the first time such a
structure is observed in the freshwater gomphonemoid diatoms.
... Studies on the diatom flora of the Himalayan region have been confined to Nepal (Jüttner et al. 2000(Jüttner et al. , 2004(Jüttner et al. , 2010a(Jüttner et al. , 2010b(Jüttner et al. , 2017Van de Vijver et al. 2011;Krstić et al. 2013), Tibet and China (Mereschkowsky 1906;Kociolek 1992;Huizhong & Jiayou 2000;Li et al. 2010aLi et al. , 2010bGong & Li 2011;Hu et al. 2013;Gong et al. 2015;Jiang et al. 2018;Liao & Li 2018). Studies on the freshwater diatoms from the Indian Territory of the region are limited to a few recent records (Das et al. 2018;Wadmare et al. 2019). Beyond floristic and biodiversity discovery studies, several efforts have also been made for ecological assessment of streams, rivers and lakes through diatom studies in the adjoining Nepalese Himalayas (Ormerod et al. 1994;Jüttner et al. 1996Jüttner et al. , 2003Sharma et al. 2012;Gurung et al. 2018). ...
... We have begun an initial survey of biodiversity discovery and floristics in Northeastern India. Das et al. (2018) described three new Gomphonema species from a river in Western Arunachal Pradesh including Gomphonema mayamae Sudipta K. Das, C. Radhakrishnan, Kociolek et B. Karthick (Das et al. 2018), which had a fimbriate structure in the girdle band near the head pole. This morphological feature is unique among the freshwater Gomphonema species. ...
... We have begun an initial survey of biodiversity discovery and floristics in Northeastern India. Das et al. (2018) described three new Gomphonema species from a river in Western Arunachal Pradesh including Gomphonema mayamae Sudipta K. Das, C. Radhakrishnan, Kociolek et B. Karthick (Das et al. 2018), which had a fimbriate structure in the girdle band near the head pole. This morphological feature is unique among the freshwater Gomphonema species. ...
A new freshwater diatom species, Gomphonema adhikarii sp. nov., is described from a small road-side pool from the alpine region of Arunachal Pradesh, Eastern Himalayas, India. Detailed valve morphological features, based on both light and scanning electron microscopy, is presented and this taxon is compared with similar species. Gomphonema adhikarii has a distinct asymmetry about the apical axis and slightly bent foot pole area. The outline of the valve is slightly undulate, the valve centre is swollen and both apices are broadly rounded. This new species described from the Eastern Himalayas supports the idea of the area being rich in biodiversity, even with respect to the freshwater diatom flora.
... WG is home to more than 150 taxa of Gomphonema (Alakananda et al. unpublished list). Gandhi described 30 Gomphonema taxa from the Western part of India, particularly from the WG (Gandhi 1956(Gandhi , 1958(Gandhi , 1959(Gandhi , 1960(Gandhi , 1964(Gandhi , 1966(Gandhi , 1970(Gandhi , 1998Gandhi et al. 1983 Karthick et al. 2015, Karthick et al. 2016, Das et al. 2018, Pardhi et al. 2020, Radhakrishnan et al. 2020a. Nearly 30 % of these species are endemic to India, especially restricted to the biodiversity-rich hotspots such as the WG . ...
A new freshwater diatom species, Gomphonema rajaguruii sp. nov., is described from a wet wall at Mahabaleshwar, Western Ghats, Maharashtra, India. The new species is described based on light and scanning electron microscopy. Features that distinguish this new species from morphologically-similar species such as G. kallarense and G. lujanense include valve shape, which is broad at the centre and narrower near the poles, a distinctly lateral, undulate raphe system and costa-like striae, which are comprised of two rows of slit-like areolae. Although G. rajaguruii also resembles some taxa from the genus Gomphoneis, such as G. eriense and its close allies, it differs from them by lacking an axial plate. The description of G. rajaguruii sp. nov. increases the knowledge on the diatom diversity in the region.
... It comprises two important biodiversity hot spots: the Eastern Himalaya and Indo-Burma. Compared to other plant groups, phycological explorations in this region are meagre (Das & Adhikary 2014), specifically diatoms, which were documented very recently (Das et al. 2018Wadmare et al. 2019;Bhatt & Karthick 2020;Radhakrishnan et al. 2020). However, there are many diatom records from the adjacent Nepalese territory (Jüttner et al. 2010a(Jüttner et al. , 2010b(Jüttner et al. , 2018Van de Vijver et al. 2011;Krstić et al. 2013;Wetzel et al. 2019;Chudaev et al. 2020). ...
We describe Adlafia kociolekii sp. nov. from aerial habitats in Sikkim, India, a part of the Eastern Himalayas. The species is described based on light and scanning electron microscopic observations. The main diagnostic features include valves are clear elliptical, a narrow axial area at the centre, radiate to convergent striation, and distinctive Voigt discontinuity at both apices. In terms of ultrastructure, the features that identify this species as new are the internally presence of raphe on the elevated sternum, with distal raphe ends distinctly deflected to opposite sides of proximal ends, and distal ends terminating in long and thickened helictoglossae. The species was also recorded from wet walls and freshwater habitats of northeast India, in the present study. The morphological features of the species are compared with other closely similar taxa of Adalfia and other naviculoid genera.
... Most of the earlier works on moss-inhabiting diatoms were confined to mountainous habitats of Polar Regions (Hickman and Vitt 1973;Beyens 1997, 1999;Alfinito et al. 1998;Gremmen et al. 2007;Kopalova et al. 2014), temperate regions (Cantonati 2001;Bertrand et al. 2004;Nováková and Pouličková 2004;Pouličková et al. 2004;Buczko and Wojtal 2005;Buczko 2006;Kulikovskiy 2008;Szulc et al. 2014) and few from other parts of the world (Round 1957;Ando 1978;Mayama 1993;Chen et al. 2012;Ress and Lowe 2014). But, the Indian Himalayan region, specifically Eastern Himalayas are devoid of any such studies so far except the taxonomic explorations started very recently (Das et al. 2018;Wadmare et al. 2019). ...
Terrestrial mosses which retain moisture provide a suitable ambience for diatoms colonization and suitable experimental platforms for observing climate change impact. The distribution and diversity patterns of such epibryic diatom communities are governed by various biotic and abiotic factors of moss habitats. The present study is first of ever attempt to investigate the moss-inhabiting diatoms in relation to various abiotic environmental variables from the Indian Himalayan Region (IHR). Samples were collected from 23 different sites in the Neora Valley National Park in Eastern Himalayas and analyzed through standard methods. Two-way indicator species analysis (TWINSPAN) and cluster analysis (CA) performed to classify the samples and habitats while direct canonical correspondence analysis (CCA) was used to determine the linkage between moss-inhabiting diatom species from various sample and abiotic environmental gradients. A total of 27 diatoms found colonizing on terrestrial moss patches from 23 sites of the park. CCA ordination plots showed that pH, conductivity and relative humidity were the primary factors influencing the diatom diversity and distribution, but altitude and temperature had no influence on the species distribution. But, correlation study on the average valve length of the most abundant and frequent taxa of Neora Valley National Park, i.e. Eunotia paludosa, E. bigibba and Hantzschia amphioxys, in relation to the environmental variables like, altitude, moisture content, relative humidity and temperature revealed a significant inference. The average valve length of these three diatoms decreases in warmer and drier climatic conditions at lower altitudes. Thus, these can be considered as potential indicator species to observe any climate change.
... Diatom studies in Indian Eastern Himalayan region are rare, with only a few recent reports (Das et al. 2018;Wadmare et al. 2019). In comparison, records of diatoms from the Nepalese Himalayas (Jüttner et al. 2004(Jüttner et al. , 2010a(Jüttner et al. , 2010b(Jüttner et al. , 2017(Jüttner et al. , 2018Van de Vijver et al. 2011;Krstić et al. 2013;Wetzel et al. 2019) are numerous. ...
A new species of Pinnularia is described from a stream from Sikkim, India, falls under Eastern Himalayas biodiversity hotspot. Features that help make this species distinctive include having triundulate margin, a broad, central fascia, a central depression, and oppositely-deflected external distal raphe fissures. Pinnularia sikkimensis sp. nov. is compared with its morphologically similar species, such as Pinnularia nodosa, P. biceps, P. grunowii, P. septentrionalis, P. graciloides var. jogensis and P. ferrophila. The taxon is also recorded from two stream sites in Vietnam suggesting a wide distribution across Southeast Asia. In addition to the description of the new species, a checklist of endemic Pinnularia taxa from India is also presented.
... The region is still unexplored in terms of diatom research is concerned. However, recent studies from the Eastern Himalayas and Meghalaya (Das et al. 2018;Wadmare et al. 2019;Roy et al. 2020) highlighted the need for exploring the diatom flora in the various habitats of Northeast India. ...
A new aerophilic species, Diploneis mawsmaii sp. nov., is here described from a speleo-environment. The species is found on mosses growing under the water dripping region of Mawsmai cave, Meghalaya state of India. It is discussed based on detailed light and scanning electron microscopic observations and compared with morphologically similar Diploneis species like D. modica Hustedt, D. modicahassiaca Lange-Bertalot & A. Fuhrmann, D. boldtiana Cleve and D. zula Kulikovskiy & Lange Bertalot. Diploneis mawsmaii possesses distinct morphological features such as a largely expanded central area bearing a prominent circular to oval central nodule and the internal structure exhibiting short striation with acute ends and the flattening of longitudinal canals at the central area. This discovery increases our understanding of cavern biodiversity in the Indo-Burma hotspot region.
... Though this place has immense floristic wealth, the history of its phycological exploration is only few decades old (Reddy et al., 1986;Singh et al., 1997;Singh and Gupta, 2000;Gupta et al., 2002;Adhikary, 2012, 2014;Das, 2015Das, , 2016, which were only restricted to some novel distributional records. Recently, Das et al. (2018) described three new freshwater diatoms species from the state. In the present study, a new chrysophycean species from this region, was described. ...
A new species of the rare chrysophycean genus Dermatochrysis Entwisle & R.A. Andersen is described from eastern Himalayas (Arunachal Pradesh, India). The comparative morphology of this taxon with allied species showed its uniqueness in thallus structure and cellular arrangements, thus is proposed as a new species, i.e. Dermatochrysis himalayensis
... But among the photosynthetic organisms, the algal flora (including diatoms) are perhaps the least studied from Sikkim (Prasad and Khanna 1987;Bhakta, Das, and Adhikary 2010;Das and Keshri 2016). Our knowledge of the diatoms from the Himalayas is very limited (Jüttner, Cox, and Ormerod 2000;Jüttner, Reichardt, and Cox 2004;Jüttner, Chimonides, and Cox 2011;Van de Vijver et al. 2011;Krstić et al. 2013;Das et al. 2018). ...
Two new diatom taxa belonging to the genus Stauroneis Ehrenberg were discovered from an aerophilic habitat in Sikkim, India, a part of the Eastern Himalayas. The morphology of Stauroneis sikkimensis sp. nov. and Stauroneis lepchae sp. nov. are illustrated with light and scanning electron micrographs and compared with similar species in the genus. S. sikkimensis is characterised by lanceolate valves with a median constriction, bluntly rounded apices, radiate striae, and a H-shaped stauros. S. lepchae has broadly elliptical to lanceolate valves with obtusely rounded apices, radiate striae, and a characteristic bow-tie shaped stauros. These are the first two diatom species described from the Eastern Himalayas of India.
... Scale bars : Figs 179, 180, 184 = 3 μm, Figs 181, 183, 185, 186 = 1 μm, Fig. 182 = 600 nm. 1 − 8) has wider striae (10 − 12 in 10 μm) and differs in ultrastructure, with C-, E-or S-shaped areola openings. Gomphonema saparense S.K. Das, C. Radhakrishnan, Kociolek & B. Karthick is wider (5.2-6.5 μm); the areola openings are mostly slit-shaped, C-shaped only along the axial area and striae become biseriate at the head pole (Das et al. 2018). (Figs 187-210) Description LM (Figs 187-200). ...
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 raraense, Gomphonema parapygmaeum and Gomphonema himalayaense. Known species included Gomphonema sublaticollum, Gomphonema cf. capitatum, Gomphonema minusculum, Gomphonema lateripunctatum, Gomphonema tergestinum (the only one previously recorded from Nepal) and Gomphonema vibrio. The history of the latter name is explained in detail. The distribution of the Gomphonema species, number of species and records in the littoral of the lake shore varied and was related to the presence of suitable substrata, land use and season, with more records and species present in spring than in autumn.
This publication is dedicated to the victims of the earthquakes which hit Nepal in 2015 and to their families.
In this study, a new Gomphonema species from Qingyi River, Anhui Province, China, was identified and named Gom-phonema qingyiensis sp. nov. We detailed its morphology using light microscopy (LM) and scanning electron microscopy (SEM). The LM and SEM photographs illustrate the size ranges and particular ultrastructure of the new species. The valves of G. qingyiensis are clavate and symmetrical to the apical axis. The headpole is broadly rounded and the footpole is narrowly rounded. The axial area is narrow, linear to linear-lanceolate. The central area is small and rectangular in shape. One stigma is evident. Striae are slightly radiate at the center. Biseriate striae and areolae are clearly evident in the LM images.
During a survey of freshwater diatoms from Xingjiang River in the north region of the Wuyi Mountains, Jiangxi Province, China, a new Gomphonema species, Gomphonema wuyiensis sp. nov., was recorded. A detailed morphological description of G. wuyiensis is herein presented, based on light and scanning electron microscopy. LM and SEM micrographs show the size ranges and ultrastructural details of the new species. Gomphonema wuyiensis sp. nov. is characterized by valve outline asymmetrical to the apical axis. In addition, the valve outline on the primary side strongly tapers from the middle part to the footpole, and less strongly on the secondary side. In addition, distinctive morphological features and ecology of the taxon
are discussed.
Diatoms were collected from the Kotulpur area of West Bengal. Four diatom taxa, namely, Eunotia minor (Kützing) Grunow, Achnanthidium minutissimum (Kützing) Czarnecki, Lemnicola hungarica (Grunow) Round and Basson, and Navicula radiosa Kützing were observed using scanning electron microscopy (SEM) and identified in light of modern diatom taxonomic trends. Except Eunotia minor, all these taxa are new records to Eastern India. A note on the taxonomy of Achnanthes pseudobiasolletiana as described by Gandhi and Eunotia serrata var. diadema (Ehr.) R. M. Patrick as reported by Dwivedi and Misra has been added.
We investigate freshwater gomphonemoid diatoms from Xinjiang and Sichuan Provinces, China, and from Glacier National Park, Montana, and compare their morphology to species in two different genera, Gomphonema hedinii Hustedt and Gomphoneis geideri Kociolek & Stoermer. These species resemble each other in the light microscope by having a relatively large, round, distinct stigma, costate striae and apical pore fields that appear like condensed striae. We describe 3 new species from Xinjiang Province, and 4 new species from Montana, based on shape, size and valve morphology. With SEM, the species all possess an internal stigma opening that has a hooded cover with small openings. The apical pore fields, like the rounded areolae, are arranged in more or less double rows, and are not physically separated from the striae. Based on the unique suite of features, we describe a new genus, Gomphosinica, and compare and contrast it with other freshwater gomphonemoid diatoms including Gomphoneis and Gomphonema. We propose a phylogenetic hypothesis detailing the synapomorphies found in the different groups of freshwater gomphonemoid diatoms. The disjunct distribution of this genus between Asia and western North America and the upper Laurentian Great Lakes is detailed, and this pattern of distribution is compared with other groups of organisms that exhibit similar patterns.
Background: The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China. It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to be broadly sympatric. Methods: We revise the Z. mollissima-Z. dixoni complex by integrating morphological, acoustic, genetic (two mitochondrial and two nuclear markers), ecological and distributional datasets. Results: In earlier field observations, we noted two very different song types of "Plain-backed" Thrush segregated by breeding habitat and elevation. Further integrative analyses congruently identify three groups: an alpine breeder in the Himalayas and Sichuan, China ("Alpine Thrush"); a forest breeder in the eastern Himalayas and northwest Yunnan (at least), China ("Himalayan Forest Thrush"); and a forest breeder in central Sichuan ("Sichuan Forest Thrush"). Alpine and Himalayan Forest Thrushes are broadly sympatric, but segregated by habitat and altitude, and the same is probably true also for Alpine and Sichuan Forest Thrushes. These three groups differ markedly in morphology and songs. In addition, DNA sequence data from three non-breeding specimens from Yunnan indicate that yet another lineage exists ("Yunnan Thrush"). However, we find no consistent morphological differences from Alpine Thrush, and its breeding range is unknown. Molecular phylogenetic analyses suggest that all four groups diverged at least a few million years ago, and identify Alpine Thrush and the putative "Yunnan Thrush" as sisters, and the two forest taxa as sisters. Cytochrome b divergences among the four Z. mollissima sensu lato (s.l.) clades are similar to those between any of them and Z. dixoni, and exceed that between the two congeneric outgroup species. We lectotypify the name Oreocincla rostrata Hodgson, 1845 with the Z. mollissima sensu stricto (s.s.) specimen long considered its type. No available name unambiguously pertains to the Himalayan Forest Thrush. Conclusions: The Plain-backed Thrush Z. mollissima s.l. comprises at least three species: Alpine Thrush Z. mollissima s.s., with a widespread alpine breeding distribution; Sichuan Forest Thrush Z. griseiceps, breeding in central Sichuan forests; and Himalayan Forest Thrush, breeding in the eastern Himalayas and northwest Yunnan (at least), which is described herein as a new species. "Yunnan Thrush" requires further study.
Centric diatoms of 107 different Hungarian running waters were investigated. Among them the largest was the River Danube, from which more than one hundred plankton samples were analysed by scanning electron microscopy (SEM). Only one sample was analysed from creeks, which were the smallest running waters analysed in this study. There were also channels with slow currents flowing out of rivers or connecting different rivers. In total, 41 centric taxa belonging to 11 genera were found during this study. The average number of taxa found in a single watercourse was 7, the maximum 40 and the minimum 1.
Macaca, comprising 20 well-characterized species, represents the largest and one of the most ecologically and socially diverse of all the nonhuman primate genera. We report the discovery of a macaque that is new to science from the high altitudes of western Arunachal Pradesh, a biodiversity-rich state in northeastern India. We propose the scientific name Macaca munzala and the vernacular name Arunachal macaque for the species. It shares morphological characteristics independently with the Assamese macaque (Macaca assamensis) and with the Tibetan macaque M. thibetana; like them, it appears to belong to the sinica species-group of the genus. However, the species is distinctive in relative tail length, which is intermediate between those of Tibetan and Western Assamese macaques, the subspecies with which it is sympatric. It is also unique in its altitudinal distribution, occurring largely at altitudes between 2000 and 3500 m. We provide a morphological characterization of the species, report preliminary data on its field biology and discuss possible taxonomic identity in relation to the other closely-related species of Macaca.
We present light and scanning electron microscope observations on six new species and one previously described endemic species of the diatom genus Gomphonema Ehrenb. from the Hawaiian Islands. The species are quite diverse morphologically. Some of the species have similarities to species previously described from other parts of the world, notably African, Indian and new world taxa, while the features found in other species are either similar to 'classical' species or have not been described previously in the genus. Based on morphology, these species do not appear to be closely related to one another, and they are widely distributed throughout the islands, with no finer-scale pattern of distribution evident. The genus Gomphonema is well represented in Hawaii, with species found in many of the streams across the state.
Earlier discussions on the biogeography of India generally seem to consider the distribution of plants and animals, the floristic and faunistic affinities and compositions and other biogeographical characters as largely static features and also unrelated to the profound and continual changes in the location, size, configuration, topography and drainage patterns of the region. This has unfortunately resulted in considerable confusion and led to untenable conclusions and curious contradictions. The distribution of plants and animals is, however, a dynamic phenomena and embraces the whole history of movements of the flora and fauna, including both gain and loss of the entire biogeographical area. This area is continually undergoing slow but complex changes, increasing in size in some parts, decreasing in size in others, shifting as a whole and coming into contact with other areas or becoming separated from them, breaking up into smaller and isolated patches or also coalescing into larger and more complex units. The present-day biogeographical characters have been derived as a result of gradual and continuous modification of past ones, which in their turn were modifications of still earlier characters. The composition, ecological characters, affinities of the flora and fauna and the distributional patterns of the plants and animals are, therefore, continually changing; we refer to these changes as biogeographical evolution.
Light and scanning electron microscopy are employed to describe the ultrastructure of Cymbella sinuata and allied taxa. Observations show the C. sinuata group shares features of valve symmetry and number of apical pore fields with members of the genus Cymbella s. str., while having raphe, striae, and stigmal features similar to Gomphonema species. The features shared between the C. sinuata group and Cymbella appear to be symplesiomorphies, while the group lacks apomorphic features characteristic of Gomphonema. These observations, in addition to a unique construction of the apical pore fields in the C. sinuata group, suggest its placement in a new genus, Reimeria. Features of the new genus are described and its systematic position discussed. A new fossil species, R. lacus-idahoensis is proposed.
Algal diversity in Arunachal Pradesh is still a little investigated area of re-search in comparison to higher plant diversity. With a view to provide base-line information about the algal diversity in the unique micro-habitat on tree bark, algae-moss association on the bark of three tree species viz. Delonix regia, Melia azadirachta and Acacia auriculiformis growing at Rono Hills in Arunachal Pradesh was studied and camera lucida drawings for a few important genera were prepared. Out of three tree species studied, A. auriculiformis exhibited maxi-mum algal diversity on its bark with 19 algal species while Delonix regia showed least algal diversity with 9 algal species . The algal flora on bark of the above three plants was dominated by Cyanophycean algae followed by a few members of Bacillariophyta and Chlorophyta. The observations of this investigation are discussed in the present paper.
Systems of classification are not hat racks, objectively presented to us by nature. They are dynamic theories developed to express particular views about the history of organisms. Evolution has produced a set of unique species ordered by differing degrees of genealogical relationship. Taxonomy, the search for this natural order, is the fundamental science of history.D.J. Gould (1987)This paper includes species investigated through many years starting with original material from museum collections. A great number of species in the genera Stephanodiscus Ehrenberg, Cyclostephanos Round and Cyclotella (Kützing) Brébisson, all in the family Stephanodiscaceae Makarova, are presented with holo-, lecto- and/or neotypes, type locality and information concerning nomenclature. A typus generis is given for each genus. Errors in the literature are pointed out and corrected.Species in the genus Stephanodiscus have the characteristic fasciculate morphology, they have fultoportulae, rimoportulae with their external tubular (long or short) extension and areolae internally with a domed cribrum both on the valve face and on the mantle. The typus generis is Stephanodiscus niagarae.Species in the genus Cyclostephanos have also the fasciculate structure, the fultoportulae, but their areolae have a domed cribrum only on the valve face and are flat on the mantle, their rimoportulae have only a simple external opening, often connected with a spine and a marginal alveolate structure, even though in some species weakly developed, which differentiate these species from those in the genus Stephanodiscus. The typus generis: Cyclostephanos novaezeelandiae.The genus Cyclotella includes species which have a smooth central area, none to several valve face fultoportulae, a simple alveolate marginal striation and the rimoportulae with an external round or slit-like opening, located on the mantle interrupting the ring of mantle fultoportulae. In some species complexes, however, the external opening of the rimoportula can be found on the valve face, near the valve face/mantle junction. The typus generis selected is C. distinguenda. Some other described species are transferred to the new genus Puncticulata Håkansson gen. nov. encompassing the species with an areolate central area consisting of areolae and valve face fultoportulae, in some species only fultoportulae in others only areolae, a complex alveolate striated marginal area, rimoportulae on the valve face at the end of a shortened interstriae. The typus generis: Puncticulata comta (Ehrenberg) Håkansson comb. nov.
Using the continental-scale collections of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program, we examined selected members of the family Gomphonemataceae to expand the current state of knowledge of diatom taxonomy, morphology, and distribution. Ten taxa in the genera Gomphonema, Gomphoneis, and Gomphosphenia are examined. The taxonomic status of two taxa is revised, and one new species is described. Two new features are described for the genus Gomphonema: slit-like areolae and ridge-like flaps or flanges on pseudosepta. Many North American gomphonemoid species appear to be restricted to certain geographic regions; the differences between western and eastern North America are striking. Trained analysts have had difficulty identifying and discriminating many of these taxa. We believe that this difficulty, in large part, results from our poor knowledge of the North American flora. Large-scale monitoring programs such as NAWQA, when teamed up with research organizations with common interests, hold great promise to expand our knowledge of the biodiversity of North American ecosystems.Key words: biogeography, Gomphoneis, Gomphonema, Gomphosphenia, National Water-Quality Assessment (NAWQA) Program, taxonomy; ultrastructure.
Ten Gomphonema taxa and four taxa of Gomphoneis from the upper Laurentian Great Lakes are considered. Gomphonema taxa include five new species and one new variety and a new record for the Great Lakes. Two new Gomphoneis taxa are described. SEM study of Gomphonema species indicates that all have occluded puncta. Occlusions may occur on the inside or outside of the valve; their position is species-specific. One Gomphoneis species possesses a stigma that is multiperforate, a condition not previously reported for the genus. Many species of both genera have extra silica on the outer valve surface. Key words: Bacillariophyceae, diatoms, Gomphoneis, Gomphonema, Laurentian Great Lakes, new species, taxonomy, SEM, ultrastructure.
Diatoms were sampled from over 200 first to third order Himalayan streams, at altitudes of 350–4700 m asl, between 1992 and 1996. This paper describes two new species, one new variety and Cymbella stuxbergii, providing extensive water chemistry and habitat data for these taxa. Gomphonema chubichuensis occurred at high altitudes (2300–4320 m) in meltwater channels or other unstable streams. Navicula obtecta was common in base-poor and nutrient-poor streams in undisturbed catchments of Nepal's Middle Hills. These species have the potential to indicate climatic change and catchment disturbance, respectively. The geographical distribution of the species was restricted: Synedra inaequalis var. jumlensis was only found in Western Nepal and north-western India, G. chubichuensis occurred from northwestern India to Central Nepal, and N. obtecta was mainly found in Eastern Nepal. C. stuxbergii has previously been recorded from more northerly latitudes, apart from one other record from the Eastern Himalaya.
Gomphonema zairense Compère, sp. nov. is formally described from wet rocks, sprayed by water under the waterfalls of the Tshopo river in Kisangani (Zaire). This new species is characterized by striae formed of double rows of puncta, unoccluded areolae and a slit-like internal opening of the stigma. It shares these characters with G. intermedium Hust., G. blandiculum Kociolek & Stoermer and some other species with which it forms a well characterized group occupying a more or less intermediate position between Gomphonema and Gomphoneis.Une nouvelle espèce, Gomphonema zairense Compère est décrite formellement; elle provient de rochers humides sous les embruns des chutes de la Tshopo à Kisangani (Zaïre). Cette nouvelle espèce se caractérise par les stries formées de doubles rangées d'aréoles, par les aréoles ouvertes extérieurement et par le stigma s'ouvrant par une fente du côté interne du nodule central. Elle partage ces caractères avcc G. intermedium Hust., G. blandiculum Kociolek & Stoermer et quelques autres espèces avec lesquelles elle forme un groupe bien caractérisé, plus ou moins intcrmédiaire entre Gomphonema et Gomphoneis.
This paper describes seven new Gomphonema species from the Himalaya and provides information about their ecology with respect to water chemistry and habitat character. Diatoms were collected during surveys of over 200 Himalayan streams between 1993 and 2000. The geographical distribution, which covers a 1000 km east-west range in the Himalaya of north-west India and Nepal, is discussed along with the occurrences of these taxa in relation to environmental conditions.
A diatom species published by Ehrenberg (1854) under the name “Gallionella campylosira” was observed and investigated in the light microscope (LM) from mica-strips found in the Ehrenberg collection at the Natural History Museum, Humboldt University of Berlin (Germany). The raw material from which the mica-strips were made has also been observed and investigated in the scanning electron microscope (SEM). According to valve morphology it was found that this taxon belongs to the genus Aulacoseira Thwaites and so its formal transfer into this genus is proposed. The observed valve morphology and ultrastructure of this species are discussed and compared with those of related species to show valve pattern variability.
Cyclotella atomus Hust., C. meneghiniana Kütz., C. comta (Ehr.) Kütz., C. antiqua W. Sm., C. michiganiana Skv., C. ocellata Pant., C. glomerata Bachmann, C. pseudostelligera Hust., and C. stelligera (Cleve et Grun.) V. H., were selected for ultrastructure investigations on the basis of their ready availability. Specimens were examined employing both transmission and scanning electron microscopy. Strutted processes, labiate processes, spines and other special features were surveyed in all species. On the basis of these observations the species of Cyclotella observed seem to be in one of 3 morphological groups, the meneghiniana group, the comta group, and the stelligera group.
Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
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