Phytotaxa 265 (3): 285–293 http://www.mapress.com/j/pt/ Copyright © 2016 Magnolia Press Article PHYTOTAXA ISSN 1179-3155 (print edition) ISSN 1179-3163 (online edition) Accepted by Saúl Blanco Lanza: 1 Jun. 2016; published: 16 Jun. 2016 http://dx.doi.org/10.11646/phytotaxa.265.3.10 285 A new Eunotia (Bacillariophyta: Eunotiales) species from Karst formations of southern China J.P. KOCIOLEK 1,2,3,* , Q-M. YOU 1,4 , J. STEPANEK 1,2 , R.L. LOWE 3,5 & Q-X. WANG 4 1 Museum of Natural History, University of Colorado, Boulder, CO 80309, USA 2 Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA 3 University of Michigan Biological Station, Pellston, MI, USA 4 College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, China 5 Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, USA * Corresponding author (E-mail:Patrick.Kociolek@colorado.edu ) Abstract We describe a new diatom species of the genus Eunotia from a karst pond in Maolan Town, a karst area in Moalan Nature Reserve, Guizhou Province, China, using light and scanning electron microscopy. The species is similar to Eunotia sudetica, differing in size and shape of the valves. Externally, the new species has striae contained in shallow, irregularly-shaped chan- nels and individual areolae have narrow openings due to the presence of rimmed occlusions. A large external opening of the rimportula occurs at one end of each valve. Internally, the new species has alveoli covering the areolae, the alveoli are partial in some specimens, present only in the middle of the valve while they extend from the dorsal margin to the ventral margin in other specimens. This species has a large rimportula and pseudosepta. In addition to the differences in extent of the alveoli, specimens differ in that some are proportionately wider than others, in the narrower valves small spines are consistently pres- ent as well as a few, shortened striae on the dorsal margin. We compare this new species with others in the genus based on its morphological features, and note similar internal alveoli in a species assigned to the genus Fragilariforma. Key words: Bacillariophyta, China, Eunotia, freshwaters, new species, karst region Introduction Karst formations are worldwide in their distribution (Hollingsworth et al. 2008). Weathering of the limestone rock creates dramatic landscapes that harbor interesting biotas, and in some parts of the world these unique places are protected as local, state or international reserves (Hamilton-Smith 1997, Ford & Williams 2007, Hollingsworth et al. 2008). In China, karst landscapes have been shown to harbor high levels of plant and animal biodiversity (Myers et al. 2000). While interest in diatoms from these types of habitats has produced some research projects (e.g. Van Landingham 1965, Carter 1971, Kashima et al. 1987, Buczkó 2003, Poulickova & Hasler 2007), only a handful of studies have originated from karst landscapes in southern China, including those by Li (2013) and Wang et al. (2009). Eunotia Ehrenberg (1837: 44) is a large (> 800 species), mostly freshwater diatom genus (but see Novitski et al. 2005), with many species being acidophilous (e.g. Berg 1939, Lowe 1974, Metzeltin & Lange-Bertalot 1998, 2007, Camburn & Charles 2000, Furey et al. 2011) and has a diversity of morphological types, some of which were recently segregated into different genera (Metzeltin & Lange-Bertalot 2007, Wetzel et al. 2012, Burliga et al. 2013). Most species of Eunotia are asymmetrical the apical axis, with punctate striae evident externally, but interrupted near the ventral portion of the valve, the raphe predominately on the valve mantle extending onto the valve face, and numerous punctate girdle bands (Kociolek et al. 2015). A total of 137 species of Eunotia have been reported from China, with less than 10 described as new (Kociolek et al. unpublished). The purpose of the present report is to formally describe a new Eunotia species, E. sudeticiformis sp. nov., and to compare this new species with other species of the genus, especially with regard to the internal valve morphology.