Aulacoseira huguang sp. nov., a new Lateglacial fossil diatom from South China

Examination of a sediment sequence from Huguangyan Maar Lake (HML) in southeast China revealed the presence of a new Aulacoseira species in samples dated to the Lateglacial. Using light microscopy (LM) and scanning electron micros-copy (SEM), this small-sized species is described as Aulacoseira huguang sp. nov. Its morphology is compared with those of similar species, such as A. subborealis (Nygaard) Denys, Muylaert & Krammer, A. pusilla (F. Meister) Tuji & Houki, A. stevensiae Weide, A. subarctica (O. Miller.) Haworth, A. scalaris (Grunow in Van Heurck) Houk, Klee & Passauer, A. dis-tans (Ehrenberg) Simonsen and A. alpigena (Grunow) Krammer. Aulacoseira huguang sp. nov. can be differentiated by the following combination of characters: valve face covered in round areolae evenly spaced, a smooth collum, small cell size, the presence of two rimoportulae located on the ringleist, positioned in opposite places on the perimeter of the valve and spines that are separated from the first row of areolae.