A new genus and a new species of Diatom from Brazilian marine waters

A new genus and a new species of Diatom from Brazilian marine waters

Clóvis Teixeira^*

RESUMO

Descrevem-se no presente trabalho um novo gênero e uma nova espécie de diatomácea marinha, pertencente à família Solenoideae, subfamilia Lauderiinae.

O material foi colhido em Ubatuba (São Paulo), na Baia de Sepetiba (Rio de Janeiro, DF) e em Abrolhos (Bahia),

Embora o novo gênero apresente certas afinidades com o gênero Guinardia, fica melhor classificado entre os gêneros da subfamilia Lauderiinae, dos quais difere pela maneira muito típica de conexão das células na formação das colônias, bem como pela completa ausência de espinhos ou dentículos marginais.

O nome genérico foi dado em homenagem ao Prof. F. C. Müller-Melchers, a quem devo minha iniciação no estudo das diatomáceas.

In this paper I refer to a new genus and a new species of diatom of the family Solenoideae from Brazilian coastal waters.

The material was collected at Ubatuba (São Paulo State), Bay of Sepetiba (Rio de Janeiro, DF) and Abrolhos Banks (Bahia State), Brazil.

The generic name has been given in honour to Mr. F, C, Müller-Melchers to whom I am indebted for my initiation to diatom investigations. I am also grateful to Dr. Fr. Hustedt (Bremen, Germany), a renown diatom specialist, who kindly confirmed the new genus and species; to Profa. Maria Helena de Araújo Andrade for taking the photographs that illustrate this paper. To all my very best thanks.

Genus Melchersiela n.g.

The new genus here described is characterized by its elongated frustules which are circular, slightly conical and convex in valvar view.

The girdle view is composed of numerous intercalary bands, a typical character of the Solenoideae.

This genus is included in the subfamily of Lauderiinae owing to its fundamental characteristics. It presents certain affinities with Guinardia of the subfamily Rhizosoleniinae.

However, this diatom differs from the other genus of the sub-family Lauderiinae specifically in the typical manner of connection of the cells, in the formation of colonies as well as in the complete absence of marginal spines and apiculi. This connection with a small cushion form is found on the margin of the valva; in case of two specimens they are disposed opposite to each other.

Melchersiela hexagolis n.sp.

(^{Pls. I-II})

Besides the characteristics of the genus this new species presents the following specific characteristics: the primary membrane is formed by a reticulation of poligonal areola (^{Pl. I}, Fig. 4a); the number of areola diminishes gradually from the center to the periphery of the valva (^{Pl. I}, Fig. 4).

The diameter of the valvar region varies from 0.040 mm to 0.075 mm. A small depression is found on the valvar face where the cushion is sustained (^{Pl, II}, ^{Fig. 1}). The girdle region is generally twice or three times larger than the valvar diameter which is 120 to 250 h long (^{Pl. II}, ^{Figs. 1-3}).

Each cells shows numerous intercalary bands in rings with poligonal structure forming a network of areola. The areola are slightly hexagonal presenting 19 areola in 0.01 mm transversaily and 16 in 0.01 mm longitudinally.

Numerous discoid cromatophores are scattered in the cellular protoplasm.

*

Supported by a grant In aid of the National Research Council, Rio de Janeiro, Brazil.

Publication Dates

• Publication in this collection
  14 June 2012
• Date of issue
  1958