<i>Leudugeria thermalis</i> sp. nov. (Bacillariophyta): a new centric diatom from shallow hydrothermal venting systems in Saba, Dutch Antilles

Abstract

Leudugeria thermalis is a new diatom species that was collected in abundance from inter-tidal shallow hydrothermal venting systems in the Caribbean island of Saba, Dutch Antilles. Frustules of freshly collected individuals were examined in light and scanning electron microscopy and their ultrastructural morphology compared to other members of the semi-circular biddulphioid diatoms, as well as to the closely related species Leudugeria janischii. Gross valve morphology and areola pattern are characters shared by both Leudugeria species, whereas smaller frustules, shorter pseudoseptum, unique cingulum structure, complete hyaline valvocopula, unusual occluded pseudocellus, and remarkable valve granulation are the characters specific to L. thermalis. The distribution and ecology of L. thermalis are discussed, particularly in relation to its occurrence in extreme environments such as hydrothermal vents