Abstract
A new species of the genus Tenuibaetis Kang & Yang, 1994 is described from Thailand and the genus is reported for the first time from this country. Tenuibaetispanhaisp. nov. is easily distinguished from other known Tenuibaetis by the complete absence of hindwing pads. Molecular evidence based on COI confirmed the validity of the new species. Additional putative species of Tenuibaetis based on molecular evidence only are considered as Molecular Operational Taxonomic Units (MOTUs) without description. The morphological characters of the new species and its closely related species are discussed; a key to the Oriental species is provided.
Highlights
Kang et al (1994) established the subgenus Tenuibaetis, and Baetis (Tenuibaetis) pseudofrequentus Müller-Liebenau, 1985 from Taiwan was considered as the type species
We describe a new species of Tenuibaetis from Thailand, based on material collected during the first mass survey of the family Baetidae in this country (Suttinun 2021)
We present cryptic diversity within this genus treated as Molecular Operational Taxonomic Units (MOTUs) based on molecular evidence only (COI), without formal description of the species (Floyd et al 2002; Blaxter et al 2005; Morard et al 2016; Kaltenbach et al 2020)
Summary
Kang et al (1994) established the subgenus Tenuibaetis, and Baetis (Tenuibaetis) pseudofrequentus Müller-Liebenau, 1985 from Taiwan was considered as the type species. Fujitani et al (2003b, 2011) questioned this transfer by stating that the larvae of Tenuibaetis, significantly differ from those of Baetiella and related genera by the inner margins of cerci fringed with setae in Tenuibaetis but glabrous in Baetiella, and the robust setae with medial ridges on the dorsomedian surface of the larval femur. Baetis ursinus Kazlauskas, 1963 and B. hissaricus Novikova, 1991, were considered to belong to this genus by Kluge (2021), but they were never formally transferred to this genus The distribution of this genus is encompassing the whole oriental realm and the most Eastern part of Palearctic realm. As Thailand is in the middle of the Oriental realm, our study will provide a better understanding of the distribution of this genus
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