A checklist covering a total of 67 Recent non-marine ostracod species from Thailand, belonging to 33 genera and seven families (Cyprididae, Candonidae, Ilyocyprididae, Notodromadidae, Darwinulidae, Limnocytheridae, Loxoconchidae), is presented. Twenty-five of these are considered endemic to the Oriental region, 17 of which are Thai endemics. Two species (Hemicypris exiqua Broodbakker, 1983, and Notodromas sinensis Neal & Zhao, 1991) are new records for the Oriental region, and four species (Cypretta seurati Gauthier, 1929, Chrissia ceylonica (Daday, 1898), Chrissia formosa (Klie, 1938), and Dolerocypris fasciata (O.F. Müller, 1776)) are new record for Thailand. The most diverse subfamily in Thailand is the Cypricercinae, with 22 species. The most diverse genera are Strandesia Stuhlmann, 1888 (eight species), followed by Pseudostrandesia Savatenalinton & Martens, 2009 (seven species) and Stenocypris Sars, 1889 (five species). Other enigmatic groups and new taxa occur in the checklist, but these need to be described elsewhere in the future. For example, several species of Cypridopsinae Kaufmann, 1900, Cyclocypridinae Kaufmann, 1900, Candoninae Kaufmann, 1900 and other groups await description. Considering regional distributions based on frequency of occurrences, rare species constitute a large fraction, whereas very common species are minor elements. Most of the records were reported from the Northern and Northeastern parts of Thailand. Sampled habitat types ranged from ponds, (oxbow) lakes, swamps, reservoirs, springs, canals, rivers, rice fields, waterfalls, and damp leaf litter. Most of the Thai ostracod fauna exists in a wide range of habitats. A brief discussion on the distribution of described species is included with the list. Additionally, in the present contribution, we describe two new species, Dolerocypris sisaketensis n. sp. and Hungarocypris suranareeae n. sp., from the Northeastern part of Thailand. The main character of Dolerocypris sisaketensis n. sp. is the presence of a spine on the postero-ventral part of the right valve; this feature sets it apart from other Dolerocypris species. Hungarocypris suranareeae n. sp. is the second species of this genus in Thailand and the third one in Southeast Asia. It is clearly distinguished from other Hungarocypris species by the serration on both valves. The genera Dolerocypris and Hungarocypris are briefly discussed and a key to the species of Hungarocypris is provided.

Species of the subfamily Cypricercinae collected from Thailand, mainly from the Northern Provinces, are here reported and/or (re-) described. Nineteen species, belonging to seven genera were found. Six new species, Strandesia hornei sp. nov., Strandesia sanoamuangae sp. nov., Pseudostrandesia gaetani sp. nov., Pseudostrandesia ovata sp. nov., Pseudostrandesia phetchabunensis sp. nov. and Pseudostrandesia thailandensis sp. nov., are described. A species list of the Cypricercinae in Southeast Asia is given and the general distribution and ecology of the Cypricercinae from Thailand is briefly discussed.

Stenocypris major major (Baird, 1859) and Stenocypris major sketi Petkovski & Meisch, 1996 were encountered in the Eastern part of Thailand. These two taxa are thus re-described based on Thai materials. The taxonomic position of S. major sketi is revised and placed as a separated species due to the distinct features in the valves and the soft parts morphology, especially in the presence of the postero-dorsal expansion on both valves, the different patterns of the posterior inner lamella margins and the caudal ramus morphology. Therefore, S. sketi Petkovski & Meisch, 1996 is erected for S. major sketi. The occurrence of S. sketi in the present contribution is the first report in Thailand and Southeast Asia. This taxon is thus far endemic to the Oriental region. The selected diagnostic characters of the genus Stenocypris are also briefly discussed.

Three new species of non-marine ostracods, Strandesia martensi n. sp., Strandesia pholpunthini n. sp. and Oncocypris rostrata n. sp., are here described from the Northeastern part of Thailand. Strandesia martensi n. sp. is similar to Strandesia perakensis Victor & Fernando, 1981 and to Strandesia sanoamuangae Savatenalinton & Martens, 2010. It can be distinguished from these two species by the presence of a large dorsal hump on both valves, large anterior overlapping, the general shape of valve, the ornamentation of valve surface and the markedly long proximal seta of caudal ramus. The main distinguishing characters of Strandesia pholpunthini n. sp. are the compression on the right valve at the posterior extremity and the fact that left valve overlaps right valve anteriorly, while right valve overlaps left valve posteriorly. This results in unequal anterior and posterior extremities, which can be seen clearly in the dorsal view. Oncocypris rostrata n. sp. is the first record of this genus in Thailand. It obviously differs from others in the beak-like anterior extremity in dorsal view, the valve structure in interior view, the valve ornamentation comprising of large pustules and large pits and the morphology of male reproductive organ, especially the first segment of the right prehensile-palp bearing a long apical spine and a large protrusion on the distal margin toward the second segment. A note on morphology, chorology and a key to the species of Oncocypris are given.

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.

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.