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Martensina thailandica gen. et sp. nov., a freshwater ostracod species representing a new subfamily, Martensininae subfam. nov., in the family Cyprididae, is here described from a swamp in Maha Sarakham Province, Thailand. The new genus and species is mainly characterized by the 7-segmented antennula which has a Rome organ and remarkably long aesthetasc ya, the morphology of the sexually dimorphic antenna (A2), the markedly elongated A2 terminal segment, the short and thin α- and β-setae on the mandibular palp, the elongated terminal segment of the maxillula, the obviously 2-segmented male prehensile palp, the presence of d1 and d2 setae on the protopod of the second thoracopod (T2), the sexually dimorphic T2, the distinctive terminal segment of the third thoracopod bearing three long setae, the well-developed caudal ramus, the large hemipenis which has a complex internal structure, and the Zenker organ with funnel-shaped ends and numerous spiny whorls.
Siamopsis gen. nov., described here, belongs to a group of genera with the right valve overlapping the left valve in the subfamily Cypridopsinae Kaufmann, 1900 of the family Cyprididae Baird, 1845. The distinguishing characters of the new genus are in the morphology of its valves and soft parts. The postero-dorsal margin of the internal left valve is plate-like protruded. The morphology of this plate varies in different species, e.g., some species bear a tooth-like tubercle on the plate. The posterior margin of the right valve is recurved inwardly at ca mid-height, resulting in the occurrence of a lobe-like expansion that can clearly be seen in the dorsal and caudal views of the carapace. In addition, the other diagnostic soft part features of the new genus are the cylindrical caudal ramus, the presence of two t-setae on the female A2 penultimate segment, the very elongated terminal segment of the Mx1 palp, the morphology of the two large bristles (tooth bristles) of the Mx1 third endite (one smooth, one serrated) and the absence of d-seta on T1. In the present paper, five new species are described under this new genus: Siamopsis renateae gen. et sp. nov., S. suttajiti gen. et sp. nov., S. conspecta gen. et sp. nov., S. khoratensis gen. et sp. nov. and Siamopsis planitia gen. et sp. nov. A key to the species of Siamopsis gen. nov. is also provided.
A new genus, Thaicypris gen. nov., in the tribe Herpetocypridini Kaufmann, 1900 of the subfamily Herpetocypridinae Kaufmann, 1900 is established to accommodate a new species from Thailand. The present contribution deals with the description of a new genus and species, Thaicypris panhai gen. et sp. nov., which is mainly characterized by the distinctive and raised, inwardly displaced selvage at the postero-ventral part of the right valve (RV) that is not parallel to the valve margin, the absence of an anterior inner list on the RV, the prominent and elevated double inner list on the posterior part of the left valve, the small and three-segmented Rome organ on the first antenna (A1), the spatulated terminal segment of the maxillular (Mx1) palp, the slender caudal ramus (CR) with long and thin Sp seta, the presence of basal triangle on the CR attachment, and the pointed projection at the terminal segment base of the prehensile palps. The hemipenis of the new genus and species is outstanding, especially the medial lateral shield which has a long, beak-shaped protrusion on the distal part. The discovery of this Thai taxon is the first record of the tribe Herpetocypridini in Thailand and the second species of the tribe in Southeast Asia.
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.
A new cypridopsine genus, Cyprettadopsis gen. nov., described here, is principally characterized by the reduced caudal ramus, the strongly serrated claw G2 of the antenna (A2), the A2 subquadrate terminal segment, the undivided penultimate segment of the second thoracopod (T2), the morphology of the third thoracopod bearing a distinctly separated terminal segment, the complete septa on the posteroventral margin and the incomplete septa on the anterior margin of both valves. Based on a combination of these characters, a new tribe, Cyprettadopsini trib. nov., is created in the subfamily Cypridopsinae Kaufmann, 1900 to accommodate this new genus, and one new species, Cyprettadopsis sutura gen. et sp. nov., is described as the type species. Apart from the above generic characters, the following features are also typical of the new species: the tiny needlepoint-like pores along the anterior and ventral margins of both valves, the remarkably large β-seta on the mandibular palp and the considerably short d2 seta on the T2. The presence of marginal septa in the new genus is a distinctive character and constitutes the first record of this feature within Cypridopsinae. The taxonomically relevant characters in the new taxon and related taxa are briefly discussed.
The new genus Thaicypridopsis gen. nov. described here belongs to the tribe Zonocypridini Higuti & Martens, 2012 in the subfamily Cypridopsinae Kaufmann, 1900. It is the first record of the Recent representatives within this tribe in Southeast Asia and Oriental regions. Thaicypridopsis gen. nov. has a number of remarkable characters that distinguish it from other genera in the subfamily: a submarginal row of distinctive tubercles on the postero-ventral part of the right valve in the interior view, a strong serrated claw G2 on the second antenna with an apical concavity, large bristles with hirsute endings and spatula-shaped apexes on all three maxillular endites and a bifurcate tip on the terminal claw of the second thoracopod. One new species, Thaicypridopsis longispinosa sp. nov., is described under this new genus in the present contribution. Apart from the above diagnostic characters, the new species also has long spines on the valve surface as its outstanding feature. The new taxon is morphologically compared with other related species and genera within and outside the subfamily Cypridopsinae. In addition, due to the new genus belonging to a group of genera with the left valve overlapping the right valve in the subfamily, a key to the genera within this group is given.
