Proceedings of the AcAdemy of nAturAl sciences of PhilAdelPhiA 162: 1-23 mArch 2013 The types of 22 Navicula (Bacillariophyta) species described by Ruth Patrick mArinA PotAPovA Diatom Herbarium, The Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, PA 19103-1195, USA. E-mail: potapova@ansp.org ABSTRACT.—The goal of this study was to investigate type materials of 22 Navicula species described by Ruth Patrick in 1959. Type specimens of two species could not be found on the holotype slides. The holotypes of 20 other taxa were located and imaged. Specimens of 11 taxa from type materials or from the type localities were investigated with electron microscopy and the details of their ultrastructure were described. On the basis of this examination, six Navicula species were transferred to other genera. The following new combinations were made: Hippodonta dulcis Potapova nom. nov., H. gravistriata (Patrick) Potapova comb. nov., Fallacia latelolongitudinalis (Patrick) Potapova comb. nov., F. duomedia (Patrick) Potapova comb. nov., Sellaphora subfasciata Potapova nom. nov., and S. secura (Patrick) Potapova comb. nov. Based on the available data, nine species described by Patrick were found to be taxonomic synonyms of taxa described earlier by other authors. Future studies of more abundant populations of Patrick’s species and type materials of the taxa assumed to be synonymous, may, however, reveal differences between them and prove some of Patrick’s taxa to be separate species. ISSN 0097-3157 INTRODUCTION In a paper published in the ANSP Proceedings, Ruth Patrick described 28 new species and varieties of the diatom genus Navicula Bory (Patrick 1959). These new species were originally illustrated only by drawings of single type specimens, and therefore, their morphology has not been well known. This is especially true for the small-sized species. Since 1959 the genus Navicula has been considerably revised and many new genera were split off. Often, a scanning electron microscopy (SEM) study is necessary to determine taxonomic placement of species that may have to be transferred from Navicula to another genus. Six species described by Patrick in 1959 have already been re-evaluated. The holotype slide of Navicula aikenensis (originally spelled “aikenenses”) was studied by Torgan and Oliveira (2001). As a result of this examination N. aikenensis was transferred to the genus Geissleria Lange- Bertalot et Metzeltin under the name Geissleria aikenensis (Patrick) Torgan & Oliveira, although it is now clear that this diatom is conspecific with Geissleria punctifera (Hustedt) Metzeltin et al., which has priority (Potapova 2010). Representatives of the genus Luticola Mann and Aneumastus Mann et Stickle have sufficiently distinct morphologies to be recognized on drawings or under light microscope (LM). Therefore, Navicula mobiliensis var. minor Patrick and N. mutica var. stigma Patrick have been transferred to Luticola without SEM examinations of type materials (Johansen et al. 2004, Mayama and Kawashima 1998), and Navicula caroliniana Patrick was transferred to Aneumastus (Lange-Bertalot 2001). The type population of N. schroeteri var. escambia Patrick has been studied by Van De Vijver and Lange-Bertalot (2009). This species has been elevated to species rank by Metzeltin and Lange- Bertalot (2007). Kociolek et al. (2009) studied the type material of Navicula creuzburgensis var. multistriata Patrick and concluded that this taxon is conspecific with Frustulia creuzburgensis (Krasske) Hustedt. The goal of this study was to investigate type materials of the remaining 22 species of Navicula described by Patrick in the 1959 ANSP Proceedings using both LM and SEM. Such examination is necessary for clarifying species identities and updating their taxonomic status. MATERIAL AND METHODS The list of examined type materials is given in Table 1. All holotype slides and some corresponding samples of the Navicula species were deposited at the ANSP Diatom Herbarium by R. Patrick. A few samples containing type materials have never been accessioned, but were found at ANSP in areas adjacent to the Herbarium. Additionally, the slide ANSP SV018300 (Savannah River, South Carolina/ Georgia, June 13, 2000) and the sample ANSP GU039000 (Guadalupe River, Texas, October 8, 1996) were examined. Permanent diatom slides were examined with a Zeiss AxioImager A1 light microscope equipped with an AxioScope MRm digital camera. Patrick marked locations of holotype specimens by diamond-scribed circles, but most slides had numerous circles. While working on the “Diatom flora of the United States”, Patrick and Reimer (1966) created an index-card file that contains “maps” of the slides that facilitate finding specimens illustrated in the book. They tried to illustrate most species described from North America by drawings of type specimens. The cards are thus indispensable for locating holotype specimens and were used in this study.