Abstract
Two new species of the subfamily Cypricercinae McKenzie, 1971 are described from the Western part of Thailand: Pseudostrandesia ratchaburiensis sp. nov. and Strandesia prachuapensis sp. nov. Pseudostrandesia ratchaburiensis sp. nov. is mainly characterized by a flange on the antero-ventral part of the left valve (LV), a markedly large β seta on the mandibular (Md) palp, serrated bristles on the third endite of the maxillula (Mx1), a slender caudal ramus (CR) with a long claw Ga (length ca half that of the ramus) and a relatively low number (13) of spiny whorls in the Zenker’s organ. The discovery of both males and females of Pseudostrandesia ratchaburiensis sp. nov. in the present study constitutes the first report of a sexual population in this genus, thereby allowing for a comparison of the male reproductive organs (hemipenis and Zenker’s organ) from a new species with those of other genera of Cypricercinae. Strandesia prachuapensis sp. nov. is most closely related to Strandesia odiosa (Moniez, 1892) and Strandesia flavescens Klie, 1932 as they bear similar anterior flanges on the right valve (RV). The key diagnostic features of the new Strandesia species are a large carapace (ca 1.5 mm), an angulated antero-ventral part of the LV, a weak and small anterior inner list on the LV, an anterior flange on the RV, a markedly small aesthetasc Y on the second antenna, a large β seta on the Md-palp, smooth bristles on the third endite of the Mx1 and a slender CR with a short claw Ga (length ca ⅓ of the ramus). In addition, Pseudostrandesia complexa (Victor & Fernando, 1981) comb. nov. is here proposed.
Highlights
The subfamily Cypricercinae McKenzie, 1971 presently consists of 11 genera (Meisch et al 2019): Astenocypris G.W
Pseudostrandesia ratchaburiensis sp. nov. is similar to P. complexa (Victor & Fernando, 1981) and P. phetchabunensis Savatenalinton & Martens, 2010
One of the discriminating characters between the genera Strandesia and Pseudostrandesia is the occurrence of the d-seta on the T1, which is present in the former and absent in the latter genus (Savatenalinton & Martens 2009b)
Summary
The subfamily Cypricercinae McKenzie, 1971 presently consists of 11 genera (Meisch et al 2019): Astenocypris G.W. Müller, 1912, Bradleycypris McKenzie, 1982, Bradleystrandesia Broodbakker, 1983, Bradleytriebella Savatenalinton & Martens, 2009, Cypricercus Sars, 1895, Diaphanocypris Wurdig & Pinto, 1990, Nealecypris Savatenalinton & Martens, 2009, Pseudostrandesia Savatenalinton & Martens, 2009, Spirocypris Sharpe, 1903, Strandesia Stuhlmann, 1888 and Tanycypris Triebel, 1959. In Thailand, Cypricercinae is the most diverse subfamily, which comprises 23 species in seven genera: Astenocypris, Bradleycypris, Bradleystrandesia, Bradleytriebella, Pseudostrandesia, Strandesia and Tanycypris (Savatenalinton & Suttajit 2016; Savatenalinton 2017). The two most diverse cypricercine genera in Thailand are Strandesia and Pseudostrandesia with eight and seven species, respectively. These two genera are close as they share several aspects, e.g., the morphology of the caudal ramus attachment and the hemipenis (see Savatenalinton & Martens 2009b). The present contribution deals with two new species of Cypricercinae, which were found in the western part of Thailand
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