Pierre Compère

Olifantiella mascarenica gen. & sp. nov., a new genus of pennate diatom from Réunion Island, exhibiting a remarkable internal process

A new diatom genus, Olifantiella gen. nov., has been discovered from the coral reefs of Réunion Island (Western Indian Ocean). This monospecific genus belonging to the Biraphidineae, contains a small, marine taxon, Olifantiella mascarenica sp. nov., which shows close structural similarity with the recently described genus Labellicula Van de Vijver & Lange‐Bertalot, but with significant differences: (i) the presence of a remarkable internal tubular process – the buciniportula; (ii) the easily identifiable external funnel‐shaped opening of this process; (iii) the design of the external raphe endings; (iv) the general shape of the frustules; and (v) a lateral void and elevated crest. The buciniportula, associated with the other characters, is apparently new, and allows the establishment of a new genus. The morphology of this genus is compared with that of related genera, such as Luticola, Diadesmis, Labellicula, Brachysira, Neidium and Nupela, with some comments on the contribution of scanning electron microscopy towards distinguishing new genera, and the possible superabundance of these new entities, particularly of small diatoms.

Two new Cocconeis taxa (Bacillariophyceae) from coral sands off the Mascarenes (Western Indian Ocean) and some related unidentified taxa

Coral sands off Réunion Island and Rodrigues (Mascarene archipelago, Western Indian Ocean) support diverse diatom communities, particularly rich in Monoraphidineae. Recent surveys of reef environments (June 2005 and June 2007) permitted the recognition of several taxa belonging to the diatom genus Cocconeis, among which are two new, relatively small taxa, epipsammic on coral sand. Cocconeis coronata Riaux-Gobin et Romero sp. nov. is similar to C. scutellum but has its own distinctive features. In external view, the concave raphe valve possesses uniseriate striae and a subsident hyaline marginal rim, while the strongly convex sternum valve has a submarginal, generally continuous crest, a hexagonal pattern of areolation, short, rounded spines that are often regularly arranged around valve face areolae, a complex areola hymen and small marginal chambers. Some morphometric differences were noted between the populations of C. coronata at Réunion and Rodrigues. Cocconeis margaritata Riaux-Gobin et Al-Handal, sp. nov. is smaller, possesses a sternum valve like that of C. placentula and C. neothumensis, but has denser striation and small pearl-like concretions around the areola aperture on the sternum valve. Several other taxa that resemble, or may be varieties of, C. margaritata require further study before being formally described. Cocconeis margaritata and C. coronata are small and relatively rare, so their study requires scanning electron microscopy.

FRAGILARIA SUBGEN. ULNARIA, COMB. NOV., THE CORRECT NAME OF THE SUBGENUS INCLUDING SYNEDRA ULNA, WHEN TREATED IN FRAGILARIA

When publishing the new subgenus name Fragiluriu subgen. Alterusynedru, Lange-Bertalot ( 1993 the first publication of the name, in Krammer & Lange-Bertalot 199 I , was invalid for lack of a Latin description) designated Frugiluriu ungeriunu Grunow as type species but definitely included in the new subgenus Frugiluriu ulna (Nitzsch) Lange-Bertalot [syn. Synedru ulna (Nitzsch) Ehrenberg], type species of the earlier Synedru subgen. Ulnuriu (Kutzing) Frenguelli (1929). Thus, Frugiluriu subgen. Alterusynedru is illegitimate as nomenclaturally superfluous when published and is to be rejected under art. 52.1 of the code (Greuter et ul. 2000). According to art. 1 1.4, the correct name of the subgenus is the combination of the earliest legitimate epithet in the same rank with the correct name of the genus to which it is assigned. Therefore, we propose here the correct name for this subgenus.

NEW DIATOM SPECIES FROM THE FEDERAL DISTRICT OF BRAZIL

As the final part of a taxonomic and ecological study of the diatoms living in two beds of aquatic macrophytes in Lagoa Bonita, Federal District of Brazil, four new species, Brachysira staurophora, Eunotia sennae, Kobayasiella mirabilis and Pinnularia sulcata are described. They occurred in several of the numerous samples examined for this study. For each taxon, morphological and ecological data are provided, illustrated by light and scanning electron micrographs. Este trabalho e a ultima parte de um estudo taxonomico das diatomaceas de ambiente metafitico de dois bancos de macrofitas aquaticas da Lagoa Bonita, Brasilia, Distrito Federal, Brasil. Sao propositos e descritos 4 novos taxons: Brachysira staurophora, Eunotia sennae, Kobayasiella mirabilis e Pinnularia sulcata. Para cada taxon, informacoes morfologicas e ecologicas, comentarios, fotografias em microscopicia optica e em microscopia electronica de varredura sao apresentadas.

Species of the Cocconeis peltoides group with a marginal row of unusual processes (Mascarenes and Kerguelen Islands, Indian Ocean)

Two diatoms related to Cocconeis peltoides Hustedt (Bacillariophyceae), from coral reef environments (Mascarenes, Western Indian Ocean), are proposed as a new Cocconeis variety and a new C. species: Cocconeis peltoides var. archaeana Riaux-Gobin et Compère and Cocconeis sigillata Riaux-Gobin et Al-Handal. Cocconeis peltoides and the two new taxa possess an unusual marginal row of small processes on their sternum valve, internally opening as curb-like structures. Several other Cocconeis species, encountered during sampling campaigns in Kerguelen (Southern Ocean, Indian Ocean sector), also share such processes, including Cocconeis hauniensis Witkowski and Cocconeis germainii Riaux-Gobin, Witkowski et Romero. The shared characteristics of these taxa are examined and compared in detail.

STAURONEIS ZAIRENSIS SP. NOV. D'UN ETANG DE PISCICULTURE A KINSHASA, ZAIRE

Stauroneis zairensis sp. nov. from a fishpond in Kinshasa, Zaire. A new species, Stauroneis zairensis, is described from a fishpond in the vicinity of Kinshasa, Zaire. The new species belongs to the small group of Stauroneis characterized by areolae arranged in longitudinal and transapical striae crossing each other at right angles. In this group, it differs from St. lineolata, St. stodderi and St. staurolineata by the much finer longitudinal striae and by the form of the central area, which is enlarged near the margins of the valves; a further difference from St. staurolineata is that the longitudinal ridges are interrupted at the stauros. The new species is illustrated and a key is given to the species of this group. Owing to the scarcity of data on the diatoms from this part of Zaire, a list is given of the diatoms accompanying S. zairensis in the original material.

New epizoic diatom (Bacillariophyta) species from sea turtles in the Eastern Caribbean and South Pacific

Obligately epizoic diatoms (Bacillariophyta) on vertebrates were first described from cetaceans, but turtles, both freshwater and marine, also host very specific floras. Several scrapings of juvenile Chelonia mydas have allowed the description of two new diatom taxa whose valves are asymmetrical about the transapical axis, Tripterion societatis sp. nov. and Chelonicola caribeana sp. nov. These taxa are very small and show some morphological plasticity. Such plasticity might suggest their inclusion in genera with slightly different characteristics from Tripterion and Chelonicola as originally delimited. Based on our observations, an emended diagnosis is proposed for Chelonicola.

Cocconeis Ehrenberg assemblage (Bacillariophyceae) from Napuka Atoll (Tuamotu Archipelago, South Pacific) with descriptions of two new taxa

A 2012 survey of Napuka Atoll (north of the Tuamotu Archipelago, South Pacific Ocean) focused on marine benthic diatoms. Possibly due to its isolation, Napuka hosts several rare or poorly known Achnanthales. Although some Cocconeis taxa are identical to those found in high islands of the same area, several others have restricted distributions, being largely present in the Tuamotu Archipelago, particularly at Napuka, i.e., Cocconeis frustrationis sp. nov., Cocconeis tuamotuana sp. nov. and Cocconeis napukensis Riaux-Gobin et al. At least 10 Cocconeis taxa are present at Napuka with C. napukensis being particularly abundant in one sample but rare elsewhere. A comparison of the new taxa with allied species is presented.

The Ultrastructure of Gomphonema augur and Gomphonema gautieri (Bacillariophyta)

Abstract The ultrastructure of Gomphonema gautieri (Van Heurck) Lange-Bert, et Metzeltin was studied based on a small population from a small Swedish, slightly acid, eutrophic river. The observations were compared with the holotype slide of G. augur var. gautieri Van Heurck, as the species was originally described in 1885. The valves are characterized in having a typical clavate outline with the largest width near the broadly rounded headpole. The species can be separated from G. augur Ehrenb. by its larger valve dimensions, the presence of broad shoulders on the headpole and the lower number of areolae per stria. Based on these differences, a separation of both taxa is justified.

New Amphicocconeis species off Mascarenes (Western Indian Ocean) and related taxa

Two new species were found on coral sediments of Mascarene archipelago: Amphicocconeis mascarenica sp. nov., relatively frequent in Réunion and rare in Rodrigues Islands, and A. rodriguensis sp. nov., relatively rare in Rodrigues and scarce in Réunion. Comparison was made with A. disculoides and A. debesii (Hustedt) De Stefano, and with species pertaining to Psammococconeis Garcia (P. brasiliensis and P. disculoides sensu Garcia). The Mascarenes taxa do not have simple raphe endings but terminal raphe fissures bent to the same side, which is a characteristic feature shared by Amphicocconeis taxa. Amphicocconeis rodriguensis has a raphe valve relatively similar to that of A. debesii (Hustedt) De Stefano, but with a denser striation; furthermore, the valvocopula of the sternum valve is narrow with simple to chiselled fimbriae. Amphicocconeis rodriguensis sternum valve is close to that of A. debesii (Hustedt) De Stefano. Amphicocconeis mascarenica shows a number of striae relatively low on both valves and both valvocopulae are generally extended and present rows of alternated small holes, which seems a unique feature for Amphicocconeis.