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Upsilococconeis dapalistriata gen. nov. & comb. nov. (Bacillariophyta) : a pantropical marine member of Cocconeidaceae

Riaux-Gobin Catherine, Witkowski Andrzej, Risjani Yenny, Yunianta Yunianta, Berteaux-Lecellier Véronique, Kryk Adrian, Peszek Łukasz, Daniszewska-Kowalczyk Genowefa

Oceanological and Hydrobiological Studies

2022

Vol. 51, No. 1

23--31

Cocconeis dapalistriata, first described as a member of the genus Cocconeis, is re-examined due to its unique ultrastructure. Both valvocopulae of this taxon show significant differences compared to those found in the genus Cocconeis. They are expanded and show some similarities with those found in Amphicocconeis. On the other hand, terminal parts of the raphe valve (RV) in C. dapalistriata are simple and the raphe valve (RV) striae are composed of small round areolae with a hymenate occlusion with radial slits, similar to those observed in Cocconeis. Campyloneis and Xenococconeis also have expanded valvocopulae but with numerous morphological differences compared to those found in C. dapalistriata. Furthermore, the areolae of the sternum valve (SV) in C. dapalistriata are occluded by a concave velum with no apparent internal slits, and externally ornamented with irregular silica crystals. Upsilococconeis Riaux-Gobin, Witkowski & Risjani gen. nov. is proposed to accommodate the latter taxon. First described from the Western Indian Ocean (Mascarenes), it was subsequently listed from the Western Pacific Ocean (Guam), the South Pacific Ocean (French Polynesia and New Caledonia) and from the Eastern Indian Ocean (Indonesia), and thus may qualify as pantropical.

New and interesting Luticola species (Bacillariophyta) from the mangroves of Nosy Be Island, NW Madagascar

Bąk Małgorzata, Kryk Adrian, Peszek Łukasz, Kociolek John P., Bemiasa John, Bemanaja Etienne

Oceanological and Hydrobiological Studies

2019

Vol. 48, No. 1

13--22

Madagascar is an isolated island characterized by a high degree of endemism at all taxonomic levels. Diatom assemblages of the region are still poorly known and sporadic sampling events in various habitats (e.g. lagoons, mangroves) have revealed a large number of taxa that could not be identified. This study presents detailed descriptions of two new species of Luticola: L. nosybeana and L. madagascarensis, collected from mangrove roots on Nosy Be Island. Comparisons with the described congeners showed that the density of striae in Luticola nosybeana is higher than that in L. belawanensis and proximal raphe endings terminate as irregular, shallow grooves. Luticola madagascarensis differs from L. similis in the shape of proximal raphe endings, which are short and expanded in the latter, while continue with irregular, shallow, elongated L-shaped grooves in L. madagascarensis. Luticola nosybeana and L. madagascarensis can be distinguished under a light microscope by the shape of the central area (bow-tie shaped in L. madagascarensis and deltoid in L. nosybeana) and isolated pores (robust and well visible in L. madagascarensis, poorly discernible in L. nosybeana). The two new species are unique in their habitat preferences: while all known congeners are freshwater, the new species inhabit estuarine mangroves.