Silvia E. Sala

Diatoms from the Colombian Amazon: some species of the genus Eunotia (Bacillariophyceae)

This research was carried out in three of the most important basins of the Colombian Amazon (Upper Solimoes, Ica and Japura Rivers). The creeks and lakes that were studied contain abundant diatom species, particularly those of the genus Eunotia. Ten species are described; five of them are registered for the first time in the Amazon basin, and six in all of Colombia. All taxa were photographed with scanning electron microscopy. Fine valve morphology of E. anamargariate, E. pseudoindica, E. triodon, and E. zydodon var. compacta is described for the first time.

REVIEW OF MATERIALS REPORTED AS CONTAINING AMPHORA COFFEAEFORMIS (AGARDH) KÜTZING IN ARGENTINA

Amphora coffeaeformis (Agardh) Kutzing has been reported in Argentina from marine and inland environments. Since this species has frequently been misidentified, we carried out a review of materials corresponding to the records of A. coffeaeformis and compared them with photographs of the type material. All analyzed materials are similar as regards valve outline and dimensions; however, they differ in valve morphology, mainly in the type of striae and areolae. The presence of A. coffeaeformis was corroborated in materials from Buenos Aires (Arroyo Tapalque), Jujuy, San Luis and La Pampa. The materials from Mar del Plata correspond to Amphora hybrida Grunow, a new record for South America, and those found in samples from Lago Nahuel Huapi correspond to A. veneta var. capitata Haworth. Six other taxa purported to be A. coffeaeformis could not be determined and will be the subject of further research. Considering that A. coffeaeformis has been reported as a potential domoic acid producer, we compared our mate...

Redefinition of Reimeria sinuata (Gregory) Kociolek & Stoermer and recognition of Reimeria uniseriata nov. spec.

Reimeria sinuata (Greg.) Kociolek & Stoermer is split into two species. The valve structure of materials from Argentina was studied in the SEM and compared with others from South Africa, North America and Europe and also with other taxa of the genus Reimeria. The specific characteristics of Reimeria uniseriata nov. spec, are uniseriate striae; 16-30 areolae in 10 μm with C-shaped foramina and one apical pore field in each pole, positioned over the mantle and valve face.

Unraveling the Identity of Fragilaria pinnata Ehrenberg and Staurosira pinnata Ehrenberg: Research in Progress on a Convoluted Story

Abstract Fragilaria pinnata Ehrenberg is one of the most commonly reported taxa in floristic and ecological works from around the world. Yet, the images published for this taxon reveal that its identity is not well defined and that several morphological variants have been ascribed to it. The present manuscript includes a preliminary analysis of the literature and type material housed in the Ehrenberg Collection, Berlin, Germany. The nomenclatural history of the taxon, a critical examination of original drawings, and results of the examination of type material lead to the conclusion that Fragilaria pinnata (current synonym: Staurosirella pinnata (Ehrenberg) D.M.Williams & Round) is not an araphid diatom, but rather an organism with links to the genus Denticula Kützing. The history of another taxon, Staurosira pinnata Ehrenberg, was also investigated to determine its actual relationship to Fragilaria pinnata since recent publications present these two names as synonyms. Staurosira pinnata also has an entangled history and a dubious current concept. Although, we have not examined type material for this taxon yet, based on examination of the nomenclatural history and original drawings, we were able to conclude that it is indeed an araphid diatom, but that the current synonymy with Fragilaria pinnata is incorrect.

Studies on Amphora subgenus Halamphora (Bacillariophyta): the revision of some species described by Hustedt using type material

As part of an analysis of type material of Amphora species described by Hustedt, the lectotypes of Amphora fontinalis, A. rugosa and A. schroederi and the holotype of A. subturgida were analysed. Light microscopy showed that all these tropical freshwater taxa are similar in frustule and valve outline, position of the raphe, appearance of the dorsal striae and thickening of the central dorsal virgae. Scanning electron microscopy allowed reliable differentiation between the four, based on the morphology of dorsal striae, dorsal areolae, conopeum, proximal raphe fissures, presence or absence of an inner longitudinal rib close to the raphe sternum, and degree of thickening of the central dorsal virgae. Previous reports of A. fontinalis from Tahiti and Moorea were confirmed while reports of this species from Australia and of A. subturgida from Mauritius, Papua and Israel were refuted. Based on our results, species descriptions are emended and the distributions of these four species are revised. Comparisons of these species and others of the subgenus Halamphora are presented.

AN EMENDED DESCRIPTION OF AMPHORA TUMIDA HUSTEDT (BACILLARIOPHYCEAE)

Material chosen as the lectotype of Amphora tumida Hustedt by Simonsen was examined with light and scanning electron microscopy. Based on this analysis a more comprehensive concept of this taxon was established and the description emended. A comparison with the morphologically similar A. subacutiuscula Schoeman and A. acutiuscula Kützing sensu Archibald strongly suggests that A. tumida is present in South African waters, in addition to its confirmed records from Venezuela and Argentina.

Revision of Amphora holsatica (Bacillariophyceae)

Material chosen as the lectotype of Amphora holsatica Hustedt and others of the type series has been examined using light and electron microscopy, and a more comprehensive concept of A. holsatica was established through an expansion of its description. In light of this new description comparisons with the related A. pseudoholsatica Nagumo & Kobayasi and A. holsaticoides Nagumo & Kobayasi were conducted. Although specimens described as A. pseudoholsatica show slight differences from A. holsatica in morphometric data, the morphology and the slope of the mantle, as well as the presence of a flap-like rib at the junction of the mantle and valve face in the former, allow us to delimit these two taxa. The specimens described as A. holsaticoides differ from A. holsatica in length and in stria density. They also exhibit subtle differences in morphology of the ventral striae, slope of the dorsal mantle and morphology of the central area, conopeum and raphe slit. These differences are considered sufficient to justify the maintenance of A. holsaticoides. A. subholsatica Krammer was also included in this analysis because the author compared it with A. holsatica in the protologue of the species. Morphometric parameters and valve morphology of A. subholsatica are, however, more similar to those of A. acutiuscula Kützing, with which it may be conspecific.

Mink (Neovison vison) as a natural vector in the dispersal of the diatom Didymosphenia geminata

Considerable resources have been invested worldwide in response to the spread of the diatom Didymosphenia geminata in rivers and streams. Considering the very low possibility of elimination of an invasive microbe, management has focused on biosecurity protocols, addressed exclusively toward the human role in dispersal (e.g. ‘check, clean dry’ campaigns and gear-washing stations for recreational users). Natural dispersal by wildlife vectors may also play an important role in the spread of D. geminata and other algal species, potentially limiting or negating the efficacy of biosecurity measures. We investigated the possibility that introduced mink (Neovison vison) may be a potential dispersal agent for D. geminata and other stream diatoms in Chilean Patagonia. Neovison were trapped near a zone of strong and persistent D. geminata blooms in the fifth order Río Simpson, and also in a fourth order upstream tributary, Río Huemules, the latter with smaller, more incipient blooms. Epibiotic D. geminata cells were identified from Neovison at Río Simpson (44% positive, average 791 cells per animal, n=18 animals), and Río Huemules (20% positive, average 40 cells per animal, n=5 animals). Many other species were also observed: 20 genera, 5683 cells per mink in Río Simpson, and 18 genera, 3605 cells per mink in Río Huemules. Navicula, Epithemia, Fragilaria and Placoneis were among the genera most frequently encountered. Neovison are known to prefer the riparian ecotone of streams of all sizes, have the capacity to travel several kilometers upstream and downstream, and possibly as far as 10 km overland to colonize new catchments. Together with an estimated survival time of 60 or more days for D. geminata in a humid environment (e.g. mink fur), Neovison represent a potentially significant factor in the colonization of upstream reaches and adjacent catchments. We comment on the potential for other wildlife vectors in Patagonia, and respective alternative patterns of short- to long-distance dispersal of diatoms in continental waters. Our results suggest that wildlife vectors should be considered in the management of D. geminata, and in the case of Neovison, integrative management of multiple invasive species, and a reassessment of conservation priorities may be necessary.

CYCLOTELLA KATIANA SP. NOV. FROM LA REINA SWAMP, PARQUE NACIONAL NATURAL LOS RATÍOS, COLOMBIA

Cyclotella katiana sp. nov. is described from La Reina Swamp, Parque Nacional Natural Los Katios, Colombia. Studied samples were collected from the stomach contents of Prochilodus magdalenae (Bocachico), an iliophagous fish species. The new taxon is distinguished from the related taxa C. atomus Kutzing, C. meneghiniana Kützing, and C. meduanae Germain, by the central valve face slightly undulated, the lack of fultoportulae in the valve face, the fultoportulae opened on every 2nd or 3rd interstriae and mantle spinulae at the valve face/mantle junction ever present. Also in the samples two other similar Cyclotella taxa were found; they were compared with the species above mentioned and with C. atomus var. gracilis Genkal & Kiss.

MORPHOLOGY AND TAXONOMY OF AMPHORA ATACAMAE FRENGUELLI (BACILLARIOPHYCEAE)

Materials containing Amphora atacamae Frenguelli from the type locality in Chile and two localities in Argentina have been examined with LM and SEM. This diatom has narrowly lanceolate to elliptic-lanceolate frustules, semi-lanceolate to slightly triangular valves with a convex dorsal margin and concave ventral margin. The raphe is filiform and slightly curved; dorsal and ventral striae are uniseriate, composed of conspicuous, transapically elongated areolae. The girdle is composed of numerous copulae. Type material of Amphora boliviano Patrick was also studied with LM and SEM, and we conclude this species should be considered a synonym of A. atacamae. The diagnosis of A. atacamae has been emended based on our observations, and a lectotype has been selected as Frenguelli did not designate a holotype slide from his collection.