Examination of the type materials of diatoms described by Hohn and Hellerman from the Atlantic Coast of the USA

摘要

In 1966, Matthew Hohn and Joan Hellerman described 44 diatom species from one freshwater and several coastal habitats along the Atlantic coast of the USA. The goal of our study was to examine the type materials of these species and to evaluate their taxonomic status. Type specimens of 32 taxa were located and documented with light microscopy, and of these, 16 were investigated further with scanning electron microscopy. Twelve taxa described by Hohn and Hellerman (Achnanthesrecava, Amphiproraincompta, Amphorabicapitata, A.delapunctata, A.pleniluna, Coscinodiscusbulla, Naviculabifax, N.scala, N.taraxa, Nitzschiasigma var.undulata, N.cryptostriata and Synedraridica) were found to be taxonomic synonyms of diatoms described prior to 1966, whereas five taxa (Amphoraallanta, Biddulphiainusitata, Cocconeisnugalas, Fragilariasilendum and F.virescens var.torus) were re-described later by other authors. Four new combinations are made here: Neodelphineissilenda (Hohn & Hellerman) Desianti & Potapova, Pleurosirainusitata (Hohn & Hellerman) Desianti & Potapova, Staurophoraagmastriata (Hohn & Hellerman) Desianti & Potapova and Staurophoracumvibia (Hohn & Hellerman) Desianti & Potapova. Lectotypes are designated for Amphoraadumbrata, A.delapunctata and Gyrosigmaincompta. An epitype is designated for Surirellastriatula var.spinifera. Taxonomic placement of seven taxa documented here (Achnanthesradiatus, Coscinodiscuslitos, Cymbellacassidula, Fragilariapelta, Naviculadelastriata, N.impertila and N.lumbricastriata) remains unclear because their type populations are extremely sparse and type specimens do not provide sufficient morphological data. This study is a necessary step in clarifying species identities and describing diatom diversity in coastal habitats.