Mallomonas weei (Synurophyceae), a new species from North Carolina, U.S.A.

A new species of Mallomonas, M.weei, is described from North Carolina, U.S.A. Fine structure of scales and bristles has been studied using scanning and transmission electron microscopy. The new species is placed in the section Mallomonas, series Intermediae.     

Two new species of Mallomonas (Synurophyceae) from the Ocala National Forest, Florida, U.S.A.

Two new species of Mallomonas, M. ocalensis and M. caerula , are described from a clearwater, acidic and oligotrophic waterbody in the Ocala National Forest, Florida, U.S.A. Mallomonas ocalensis , in the Series Doignonianae of the Section Torquatae, consists of relatively small cells with scales that have a series of parallel shield ribs with alternating thicknesses, collar scales with very short bristles and posterior scales with small protruding spines. Mallomonas ocalensis is most similar to Mallomonas dickii , but is distinguished from the latter species based on the highly variable thicknesses of the shield ribs and significantly larger scales. Mallomonas caerula , in the Series Mallomonas of the Section Mallomonas, consists of relatively large cells that bear large domed and dorneless scales, and long, robust and ribbed bristles. Bristles with and without helmets can be found. The shield, especially the distal portion, and the posterior flange of scales consists of series of more or less parallel ribs. Mallomonas caerula appears to be most closely related to Mallomonas acaroides var. acaroides and Mallomonas acaroides var. muskokana , but can be distinguished from the latter taxa on the basis of scale type, scale structure and bristle morphology. Both new species were found in the plankton and surface sediments of Blue Sink Pond.     

Mallomonas wujekii (Synurophyceae), a new species from Florida, U.S.A.

A new species of Mallomonas, M. wujekii sp. nov., belonging to the Series Tonsuratae is described from a dilute, acidic locality in Florida, U.S.A. Bristle bearing domed scales are restricted to the anterior end, and scales are orientated with their longitudinal axes at a 60° to 90° angle with the longitudinal axis of the cell. Cells have three types of scales, domed anterior scales, domeless body scales and spined posterior scales. All scales possess papillae that are restricted to the shield and have one rib positioned on each end of the posterior flange. The new species is believed to be most closely related to Mallomonas tonsurata and M. galeiformis . The combination of characters of the bristles is unique among taxa of Mallomonas .     

Mallomonas corymbosa var. interrupta nov. var. (Synurophyceae) from Argentina

A new variety of Mallomonas corymbosa is described from a pond in Nahuel-Huapi National Park (Argentina): M. corymbosa var. interrupt nov. var. Fine structure of scales and bristles has been studied by scanning and transmission electron microscopy.     

Three new species of Mallomonas (Chrysophyceae, Mallomonadaceae) from Lake Lanalhue, Chile

Three new species of the genus Mallomonas are described. Mallomonas rasilis sp. nov. belongs to the sect. Mallomonas , ser. Papillosae , while M. scalaris sp. nov. and M. lanalhuensis sp. nov. are members of the sect. Torquatae. They were found in Lake Lanalhue, Arauco Province, Chile. The taxonomy and distribution of these species is discussed, along with the morphology of cells, scales and bristles, based on scanning and transmission electron microscopy.     

Mallomonas canina sp. nov. (Chrysophyceae), a new member of sect. Heterospinae

Mallomonas canina sp. nov. is described from a Danish lake by means of electron microscopy of scales and bristles and compared with the other members of the Mallomonas sect. Heterospinae Momeu & Péterfi.     

Mallomonas connensis sp. nov., a new species of Synurophyceae from a small New England lake, U.S.A.

A new species of Mallomonas, M. connensis sp. nov., is described from a eutrophic locality in Connecticut, U.S.A. with a relatively high pH and specific conductance. Cells are covered with bristles and have scales that are orientated with their longitudinal axes perpendicular to the longitudinal axis of the cell. Each scale of the apical ring is highly asymmetrical with a forward projecting triangular shaped extension; collectively the extensions form an opening through which the flagellum emerges. Body scales possess a prominent Ushaped ridge that transverses the scale near the center and extends forward. A series of more or less concentric ribs cover the U-shaped ridge and dome, and circumscribe a more light and electron transparent region. The combination of characters of the bristles is unique among taxa of Mallomonas .     

The taxonomy of problematic Mallomonas species (Synurophyceae). II. Mallomonas costata and M. galeiformis

Whole cells of Mallomonas costata and Mallomonas galeiformis with complete scale and bristle complements present few problems for their identification by TEM. Individual scales however, such as those usually encountered in paleolimnology, have often been difficult to identify in isolation. Both species occur in collections from Ontario, Canada, but M. galeiformis is apparently more acidophilic than M. costata . Several differences in structure of scales from both species are described which, if used as criteria for distinguishing between the two species, should facilitate identification of individual scales.     

Taxonomic significance of asymmetrical helmet and lance bristles in the genus Mallomonas (Synurophyceae) and their discovery in Eocene lake sediments

Complex bristle types formed by species in the genus Mallomonas include those with helmet or lance-shaped apices. The ornamentation on each side of the helmet has been thought to be equivalent or symmetrical, whereas on a lance-shaped bristle an expanded portion folds over one side of the shaft to form an asymmetrical structure. We describe, for the first time, helmet bristles with a distinctly asymmetrical design, also formed by the folding of a siliceous membrane over one side of the helmet. We postulate that the asymmetrical helmet represents a structure that combines the formation of a symmetrical helmet and a lance-shaped design on the same bristle. Further, we report structurally similar asymmetrical helmet bristles, lance-shaped bristles and scales that are unambiguously assigned to Mallomonas asmundiae in Middle Eocene sediments from a maar lake in northern Canada, supporting the hypothesis that scale and bristle morphology in the Synurophyceae has undergone extensive prolonged evolutionary stasis. Given differences in scale morphology and the presence of asymmetrical helmet bristles, we transfer the North American endemic Mallomonas acaroides var. muskokana to the rank of species. Further, we formally describe Mallomonas dispar and M. lancea, fossil species with asymmetrical helmet bristles and lance-shaped bristles, respectively. The taxonomic and biogeographic significance of asymmetrical and lance-bearing bristles is discussed.     

Mallomonas retrorsa, a new species of silica-scaled Chrysophyceae with backwards orientated scales

A new species, Mallomonas retrorsa , with a unique siliceous armour, is described from four slightly humic and acidic localities in Connecticut, U.S.A., each low in specific conductance. Cells of the new species have three types of siliceous scales each of which is asymmetric, domeless and arranged with their longitudinal axis parallel to the longitudinal axis of the cell. The scales are positioned such that the posterior rim of each scale faces the apical end of the cell. In addition, the new taxon has an apical whorl of very small, forward projecting paddle-shaped bristles that emerge from the rimmed ends of the apical scales, and an elongated caudal region.     

Two new taxa in the Section Papillosae of the genus Mallomonas (Synurophyceae) from the Ocala National Forest, Florida, USA

Two new species of Mallomonas, M. binocularis and M. delanciana , are described from small, acidic, poorly buffered waterbodies in the Ocala National Forest, Florida, U.S.A. Both taxa are in the Section Papillosae, consist of relatively small cells covered with domed scales each bearing a single bristle, and have small tripartite scales with a small symmetrically placed dome. Scales of Mallomonas binocularis have shields that are covered with evenly-spaced papillae, two distinctive pores at the base of the V-rib and unornamented flanges. Mallomonas binocularis is most similar to Mallomonas paxillata, M. papillosa, M. rasilis and M. calceolus , but can be distinguished from the latter taxa on the basis of scale structure and bristle morphology. Scales of Mallomonas delanciana have shields with widely spaced papillae, a series of parallel ribs on the anterior flanges that usually continue around the dome, unornamented posterior flanges and lack rimmed pores in the posterior region of the shield. The density of the papillae on the shield, features of the dome and anterior flange, and the structure of bristles, clearly serve to separate M. delanciana from closely related species including M. papillosa, M. calceolus and Mallomonas conspersa.     

Mallomonas robusta (Chrysophyceae,Synuraceae): Electron microscopical study of silica armour

Mallomonas robusta (Matvienko)Péterfi & Momeu (Mallomonopsis robusta) has been investigated by transmission electron microscopy and is redescribed in detail. Its silica armour, consisting of scales and bristles, exhibits a very peculiar fine structural pattern. Differences and possible relationships with other species are discussed. The Romanian material is designated as the nomenclatural type (neotype).     

Mallomonas jejuensis sp. nov. (Synurophyceae) from Jeju Island,South Korea

A new species of Mallomonas (Synurophyceae), Mallomonas jejuensis sp. nov., has been found in Jeju Island, South Korea. This species is placed in the series Mangoferae (section Torquatae) because it has a collar of elongated domed scales, domeless body scales, rear scales with spines and all scales ornamented with papillae. The morphological characteristics of the scales and bristle of the new species are described by EM and compared with those reported for the other species of the series Mangoferae.     

Exploring Cryptic Diversity and Distribution Patterns in the Mallomonas kalinae/rasilis Species Complex with a Description of a New Taxon—Mallomonas furtiva sp. nov.

A complex of closely related Mallomonas taxa belonging to the section Papillosae, M. kalinae ?ezá?ová and M. rasilis Dürrschmidt, has been studied in detail by molecular and morphometric methods. Our investigations uncovered the existence of a new species found in water bodies in Vietnam, which we describe here as Mallomonas furtiva sp. nov. This taxon is morphologically very similar to M. kalinae , from which it differs by minute, but statistically significant morphological differences on the structure of silica scales. Indeed, the principal component analysis of morphological traits measured on silica scales significantly separates all three species in the complex. Mallomonas kalinae and M . furtiva differ by number of papillae on the shield and the dome, as well as by the scale sizes. Likewise, Mallomonas rasilis and M. furtiva are primarily differentiated by the absence of submarginal anterior ribs on silica scales of the former species. Phylogenetic analyses showed that Mallomonas furtiva is closely related to M . kalinae , with which it formed a highly supported lineage. Distribution patterns of all three studied taxa are further discussed.     

Morphological variation and ecology of Mallomonas crassisquama (Chrysophyceae)

Siver, P. A. & Skogstad, A. 1988. Morphological variation and ecology of Mallomonas crassisquama (Chrysophyceae). - Nord. J. Bot. 7: 99–107. Copenhagen. ISSN 0107–055X.
Mallomonas crassisquama is one of the most common and widely distributed species of Mallomonas . In this study we compare the morphology and ecology of the species based on 309 collections from 67 localities in Connecticut (U.S.A.) and Norway. The taxon produces a very complex siliceous coat consisting of four scale and two bristle types all of which have considerable structural variation. A new variety, M. crassisquama var. papillosa is described. Bristle production was found to be temperature dependent where cells formed serrated or helmet bristles under cold or warm conditions, respectively. M. crassisquama was found to exist over wide temperature, conductivity, phosphorus and pH ranges, however, was absent in samples with a pH <5.5.     

SEPERATION OF MALLOMONAS DUERRSCHMIDTIAE SP. NOV. FROM M. CRASSISQUAMA AND M. PSEUDOCORONATA: IMPLICATIONS FOR PALEOLIMNOLOGICAL RESEARCH1

A new species, Mallomonas duerrschmidtiae, with characteristics common to both Mallomonas crassisquama (Asmund) Fott and Mallomonas pseudocoronata Prescott, is described from acidic lakes low in specific conductance and total phosphorus concentration. Characteristics of scales, bristles and spines serve to separate the three taxa. The length and area of scales of M. duerrschmidtiae are significantly larger than those of M. crassisquama but smaller than those of M. pseudocoronata. Although the anterior submarginal ribs of scales of M. duerrschmidtiae may become extended to form short wings, the scales lack the large forward projecting anterior wings characteristic of scales of M. pseudocoronata. Features of the dome and junction between the arms of the V-rib and anterior submarginal ribs also serve to distinguish between the three species. Cells of M. duerrschmidtiae also possess long, smooth and thick spines on their posterior scales and lack helmet bristles. M. duerrschmidtiae has different maxima along pH, temperature, specific conductance, total phosphorus and seasonal gradients than either M. crassisquama or M. pseudocoronata. Discriminant analysis, based on nine morphological characters, was used to successfully classify body scales of the three species. The importance of M. duerrschmidtiae as a bioindicator in future lake monitoring and paleolimnological inference studies is discussed.     

Mallomonas nieringii sp. nov., a new species of Synurophyceae from a suite of ponds on Cape Cod, Massachusetts, U.S.A.

A new species of Mallomonas, M. nieringii sp. nov., is described from a small, poorly buffered, acidic locality on Cape Cod, Massachusetts, U.S.A. Cells are covered with uniquely sculptured scales, each scale of which may possess a single bristle. Cell, scale and bristle morphology all indicate that this new species should be placed within the series Punctiferae of the section Punctiferae, which now has four recognized species and one variety. Scales of the apical ring are highly asymmetric in design, each with a forward projecting triangular shaped spine. Collectively, the triangular shaped extensions of the apical ring of scales surround a single emergent flagellum. Body scales resemble those of Mallomonas punctifera and M. transsylvanica in shape and general morphology, but differ in lacking distinct secondary ribbing on the shield. Mallomonas nieringii was found in six waterbodies all situated within a small geographic area on the outer tip of the Cape Cod peninsula.