Ditmar Metzeltin Livres

Covers geographically the area from Paraguay to continental Central America, Caribbean Islands and Florida. 190 taxa are described as new to science (in addition to the 202 taxa published in volume 5): 180 species, 2 subspecies, 8 varieties, and the new genus PERINOTIA belonging to the family Eunotiaceae. Type species is Perinotia jankae n. sp. from Brazil. Altogether 680 new and earlier established taxa or 'non-taxa' are documented here photographically. Not counted are numerous depicted specimens that are assumed to belong to established species (marked as cf. or aff.). In addition, 31 established taxa had to be transferred to other than the original genera (nov. comb.), 19 to a nov. stat. For 6 taxa the original name had to be replaced by a new one (nov. nom.).

For the first time specimens of the type material of Echinella geminata Lyngbye 1819 are documented with light- and scanning-electron-microscopical photographs. This is the reference point for various other presented morphodemes of Didymosphenia geminata originating from five continents and subcontinents or floristic regions respectively. 22 species can be differentiated morphologically among which 11 plus one subspecies are proposed and described here as new to science. Formerly established taxa, for a part in a lower taxonomical rank than recently, are: Didymosphenia clavaherculis (Ehrenberg) Metzeltin & Lange-Bertalot 1995, D. curvata (Skvortzow & Meyer) Metzeltin & Lange-Bertalot 1995, D. curvirostrum (Tempère & Brun) M. Schmidt 1899, D. dentata (Dorogostaisky) Skvortzow & Meyer 1937, D. fossilis Horikawa & Okuno 1944, D. geminata (Lyngbye) M. Schmidt 1899 ssp. geminata, D. lineata Skabichevsky 1983, D. pumila Metzeltin & Lange-Bertalot 1995, D. siberica M. Schmidt 1899, D. subcapitata (Skvortzow & Meyer) stat. nov., D. tatrensis Mroziska, Czerwik-Marcinkowska & Gradziski 2006. Proposed as taxa new to science are: Didymosphenia clavamagna, D. coronata, D. crassiporata, D. geminata ssp. crassa, D. grunowii, D. laticeps, D. laticollis, D. mongolica, D. nipponica, D. skvortzowii, D. strelnikovae.

The first contribution in this volume investigates mainly the province of Khentii, covering an area with dominating higher or lower mountain ranghes and tablelands above 600 m. s. l. Thus the diatom flora was supposed to resemble alpine and northern regions of Europe rather than mediterranean - like or subtropical regions, which proved to be correct. The 3487 micrographs reproduced in this book encompass approximately 615 taxa - without any attempt to approach completeness in this first volume of a treatise. 65 taxa (64 from Mongolia) are described as new to science, 33 other taxa will prove probably as new species after some more information, about 114 taxa could not convincing characters to be distinguished from more or less similar taxa. - The second smaller monograph in this volume deals with Sichuania lacustris, a biraphid diatom possessing an unique frustule morphology, completely dissimilar to all established taxa from freshwater habitats.

This treatise on tropical diatoms from South America may serve as a pilot study introducing a representative selection of neotropical diatoms. The neotropical diatom flora is completely different from the flora of other continents and also different from the diatom flora of the temperate climatic zones of the subcontinent. About 700 taxe are documented here by 2515 micrographs. Most of them have been found exclusively in the tropical zone of South America where 202 are described as new taxa. Moreover, about 130 „morphotypes“ are documented and taxonomically indeterminated (new) species. The extent of real endemic elements has still to be determined since identity and distribution of tropical diatoms are still poorly investigated. Nevertheless, it can be shown that many of these species are indicative characteristic elements of oligotrophic or oligodystrophic so-called clearwater- and blackwater rivers. Many established taxa so far recorded as a single specimen only or considered to be rare, have now been found to be widespread in different parts of Brazil, Guyana and Venezuela, where waters have not been under the negative influence of human activities.

96 taxa and 1 genus (Germainiella) are described as new to science.- Contents: Summary / Resumen/ Areas of examination/ Región de las examinaciones/ List of selected sampling locations/ Lista de localidades de muestreo seleccionadas/ Some special results/ Algunos Resultados Especiales/ Quickfinder for plates/ Descriptions of new species in this book/ Acknowledgements/ References/ Index of the Taxa.