Three new subaerial Achnanthidium (Bacillariophyta) species from a karst landform in the Guizhou Province, China

Abstract

Three new subaerial species of Achnanthidium are examined and described from a karst landform of central-south China based on light and scanning electron microscopy observations, and are compared with similar taxa worldwide. A. mediolanceolatum sp. nov. is elliptical-lanceolate, not linear-lanceolate as is more typical in this genus, as well as having a bow-tie shaped central area on the raphe valve and a large lanceolate axial area on the rapheless valve, features which together make it easy to distinguish this species from others. A. parvulum sp. nov. and A. guizhouensis sp. nov. are linear-elliptical in shape, which is more common for Achnanthidium and they differ from other species mainly in size, raphe, density of striae and shape of the central area. We compared these three new species with morphologically-similar taxa, and present their ecological settings and distributions as well. The relationship between Achnanthidium and Psammothidium is discussed, and the data from these new species from Guizhou presented herein suggest the two genera are difficult to separate.

Two new freshwater species of the genus Achnanthidium (Bacillariophyta, Achnanthidiaceae) from Qingxi River, China

“…The two new species possess characters that support their assignment to the A. pyrenaicum complex, deflected external distal raphe fissures ( Yu et al 2018 , 2019 b, You et al 2019 , 2021 ).…”

“…Later, Round and Bukhtiyarova (1996) redefined the circumscription of this genus, with the main identification characteristics of Achnanthidium including small cells with a length and width of usually less than 30 µm and 5 µm, respectively, linear-lanceolate to lanceolate-elliptic valves and straight or curved external distal raphe ends ( Round and Bukhtiyarova 1996 ; Yu et al 2019 a, b). Species of Achnanthidium are widely distributed in various types of freshwater habitats in which they are common and abundant ( Novais et al 2011 ; Pinseel et al 2015 ; Karthick et al 2017 ; You et al 2019 ; Yu et al 2019a , b ).…”

“…It is, therefore, necessary to collect samples from the type locality, and re-evaluate their taxonomic position ( Liu et al 2021 ). From 2001 to 2021, 14 new Achnanthidium species have been described from China ( Liu et al 2016 ; Yu et al 2018 , 2019a , b , You et al 2019 , 2021 ; Liu et al 2021 ). During an investigation of the freshwater diatoms from the Qingxi River, two unknown Achnanthidium species were discovered.…”

Substratum‐associated microbiota

“…nov., and A. guizhouensis P.Yu, Q.You et Kociolek sp. nov. from subaerial environments in the Guizhou Province (You et al, 2019).…”

Continental diatom biodiversity discovery and description in China: 1848 through 2019

“… sinica Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthes pseudoexigua Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthes pseudoexigua var. unilateralis Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthes radiata Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthes rarissima Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthes striatella Skvortzov ex Gololobov & Kulikovskiy in Kulikovskiy et al 2012 Achnanthidium epilithica P.Yu, Q-M.You & Q-X Wang in Yu et al 2019c Achnanthidium guizhouensis P.Yu, You & Kociolek in You et al 2019a Achnanthidium jiuzhaienis P.Yu, Q-M.You & Q-X Wang in Yu et al 2019c Achnanthidium lacustre P.Yu, Q-M. You et Kociolek in Yu et al 2019b Achnanthidium limosua P.Yu, Q-M. You & Q-X Wang in Yu et al 2019c Achnanthidium longissimum P.Yu, Q-M.You & Kociolek in Yu et al 2019a Achnanthidium mediolanceolatum P.Yu, Q-M.You & Kociolek in You et al 2019a Achnanthidium parvulum You, Q-M.You & Kociolek in You et al 2019a Achnanthidium sinense B.Liu & S.Blanco in B. Liu et al 2016 Achnanthidium sublanceolatum P.Yu, Q-M.You et Kociolek in Yu et al 2019b Achnanthidium subtilissimum P.Yu, Q-M.You & Q-X Wang in…”