Achnanthidium neotropicum sp. nov., a new freshwater diatom from Lake Apastepeque in El Salvador (Central America)

Abstract

A new freshwater diatom recovered from modern and subfossil sediments of Lake Apastepeque in El Salvador, Achnanthidium neotropicum sp. nov., is described based on light and scanning electron microscopy observations. The species is characterized by valves with linear, sometimes centrally constricted (mainly in large cells), outlines, broadly rounded to subrostrate apices, and often rectangular fascia. Striae are composed of 3-4 rounded to slit-like areolae. It can be separated from similar species by valve outline, together with striae density, and number of areolae per stria. Based on the straight distal raphe endings this species can be assigned to the A. minutissimum complex. The new species is compared to morphologically resembling species from the genus Achnanthidium Kützing.

Substratum‐associated microbiota

“…C. E. Wetzel sp. nov. described from Lake Apastepeque in El Salvador fits in the A. minutissimum (Kützing) Czarnecki complex (Krahn, Wetzel, Ector, & Schwalb, 2018). Potapova 2018 (Shi et al, 2018).…”

Five new Achnanthidiaceae species (Bacillariophyta) from Jiuzhai Valley, Sichuan Province, Southwestern China

“…Later, Round et al (1990) and Round & Bukhtiyarova (1996) re-established Achnanthidium as a new separate genus. Species belonging to Achnanthidium commonly, abundantly, and frequently occur in various freshwater habitats, such as streams, rivers, and lakes (Potapova & Ponader 2004, Kobayasi et al 2006, Pinseel et al 2015, Karthick et al 2017, Krahn et al 2018. Moreover, Achnanthidium species can occur across a broad range of freshwater habitats, from oligotrophic to eutrophic waters (Potapova & Hamilton 2007, Karthick et al 2017, Krahn et al 2018, Yu et al 2019.…”

“…However, species recognition within the genus Achnanthidium has presented some challenges in terms of research. Such species are usually small in size, possess fine striations, and have a limited number of morphological characteristics that are clearly visible in light microscopy (LM), and these variable diagnostic features often overlap when measured (Ponader & Potapova 2007, Karthick et al 2017, Marquardt et al 2017, Krahn et al 2018. For now, to obtain adequate identification characteristic, use of scanning electron microscopy (SEM) is often necessary.…”

“…For now, to obtain adequate identification characteristic, use of scanning electron microscopy (SEM) is often necessary. (Krahn et al 2018).…”

“…To date, three complexes have been characterized in the Achnanthidium genus: (1) members of the A. minutissimum (Czarnecki 1994: 157) complex, have straight external distal raphe ends, and striae density that increase towards the apex; (2) members of the A. pyrenaicum (Kobayashi 1997: 148) complex, have external distal raphe ends that deflect or hook to one side of the valve; and (3) members of the A. exiguum (Czarnecki 1994: 157) complex, have external distal raphe ends curved in opposite directions (Round & Bukhtiyarova 1996, Krahn et al 2018, Pinseel et al 2015, Compère & Van de Vijver 2011, Jüttner et al 2011, Yu et al 2018, 2019. Currently, more than 200 Achnanthidium species have been reported in the literature worldwide (Marquardt et al 2017, Yu et al 2019.…”