Integrative Taxonomy of Cyclocyprididae Kaufmann, 1900 (Ostracoda: Podocopa) with Description of a New Genus and Species.

The two widespread ostracod genera Cypria Zenker, 1854 and Physocypria Vávra, 1897 are traditionally distinguished based on the presence or absence of tubercles on the right valve margin. However, recent research based on soft body parts has uncovered new cryptic genera within Cypria and Physocypria. Following this line of research, a new Cyclocyprididae genus and species, Vizcainocypria viator gen. nov. sp. nov., is here described from individuals collected in rice fields and wetlands of the Iberian Peninsula. Vizcainocypria is compared with Cypria, Physocypria, Dentocypria Savatenalinton, 2017, Keysercypria Karanovic, 2011, Brasilocypria Almeida et al., 2023, and Claudecypria Almeida et al., 2023 based on morphological evidence. Besides the presence or absence of tubercles on the right valve, these genera can be distinguished according to their mandibular palp, second thoracopod, caudal ramus, and male hemipenis. Molecular analyses using mitochondrial (COX1), and nuclear (28S rDNA) genes provide further support for the differentiation of Cypria, Dentocypria, Physocypria and Vizcainocypria gen. nov. The present study highlights the importance of using an integrative taxonomy approach, combining shell and soft-body parts morphology and molecular data, to characterize the rich diversity of freshwater ostracods.

Songkhramodopsis gen. nov., a new genus of Cypridopsinae (Crustacea: Ostracoda) from Thailand.

A new genus and species of subfamily Cypridopsinae Kaufmann, 1900, Songkhramodopsis meischi gen. et sp. nov., is described from the Lower Songkhram River Basin, Thailand. The prominent diagnostic characters of the new genus mainly exist in antennula (A1), antenna (A2) and third thoracopod (T3): the six-segmented A1, the strongly serrated claw G2 on the female A2, the large aesthetasc Y with remarkably large and striated third section and the completely separated terminal segment of T3. The A1 with six segments, together with the distinctive morphology of aesthetasc Y, have been recognized for the first time in the Cypridopsinae. A new tribe, Songkhramodopsini trib. nov., is also erected to accommodate this exceptional new genus and species. The new taxon is also characterized by the left valve overlapping the right valve, the anterior and posterior inner list on both valves, the widely inwardly displaced posterior selvage on right valve, the bifurcate-like tip of an apical ventral seta on A1 first segment, the absence of d1 seta on second thoracopod (T2), the divided penultimate segment of T2, the female caudal ramus with cylindrical base, the very small number of spiny whorls of Zenker organ. A key to tribes of Cypridopsinae is provided.

Redescription of Neocypridella fossulata (Daday, 1910) (Crustacea: Ostracoda) and description of a new subfamily.

Neocypridella fossulata (Daday, 1910) is redescribed based on type material from the Daday collection (Hungarian Natural History Museum, Budapest). The major diagnostic characters of the genus are the ovate shape of the carapace in lateral view, with the left valve overlapping the right valve, the absence of marginal septa on the valve margins, the right valve anterior selvage not inwardly displaced, the presence of a Wouters organ on the first antenna, the divided penultimate segment of the second antenna, the markedly large -seta on the mandibular palp, the subquadrate terminal segment of the maxillula palp, the divided penultimate segment of the second thoracopod with setae d1 and d2 both long, the slender caudal ramus and the slender caudal ramus attachment with thin dorsal and ventral branches. Neocypridella fossulata can be further characterized by the oblique carapace in frontal view, the two smooth bristles on the maxillula third endite and the thin and long Ga claw of the caudal ramus, which is c. 3/5 of the length of the ramus. The morphology of Neocypridella is compared with related taxa and the taxonomic position of the genus is discussed. This revealed that Neocypridella cannot be assigned to any of the extant subfamilies in the Cyprididae. Therefore, a new subfamily, Neocypridellinae subfam. nov., is erected.

Redescriptions of Stenocypris major major (Baird, 1859) and Stenocypris major sketi Petkovski amp; Meisch, 1996 (Ostracoda: Crustacea), with discussion on their taxonomic position.

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.

Transitions in functional morphology from "large branchiopods" to Cladocera: Video and confocal microscopic studies of Cyclestheria hislopi (Cyclestherida) and Sida crystallina (Cladocera: Ctenopoda).

Great diversity is found in morphology and functionality of arthropod appendages, both along the body axis of individual animals and between different life-cycle stages. Despite many branchiopod crustaceans being well known for displaying a relatively simple arrangement of many serially post-maxillary appendages (trunk limbs), this taxon also shows an often unappreciated large variation in appendage morphology. Diplostracan branchiopods exhibit generally a division of labor into locomotory antennae and feeding/filtratory post-maxillary appendages (trunk limbs). We here study the functionality and morphology of the swimming antennae and feeding appendages in clam shrimps and cladocerans and analyze the findings in an evolutionary context (e.g., possible progenetic origin of Cladocera). We focus on Cyclestheria hislopi (Cyclestherida), sister species to Cladocera and exhibiting many "large" branchiopod characters (e.g., many serially similar appendages), and Sida crystallina (Cladocera, Ctenopoda), which likely exhibits plesiomorphic cladoceran traits (e.g., six pairs of serially similar appendages). We combine (semi-)high-speed recordings of behavior with confocal laser scanning microscopy analyses of musculature to infer functionality and homologies of locomotory and filtratory appendages in the two groups. Our morphological study shows that the musculature in all trunk limbs (irrespective of limb size) of both C. hislopi and S. crystallina comprises overall similar muscle groups in largely corresponding arrangements. Some differences between C. hislopi and S. crystallina, such as fewer trunk limbs and antennal segments in the latter, may reflect a progenetic origin of Cladocera. Other differences seem related to the appearance of a specialized type of swimming and feeding in Cladocera, where the anterior locomotory system (antennae) and the posterior feeding system (trunk limbs) have become fully separated functionally from each other. This separation is likely one explanation for the omnipresence of cladocerans, which have conquered both freshwater and marine free water masses and a number of other habitats.

Two new species of Cypretta Vávra, 1895 (Crustacea, Ostracoda) from Thailand and discussion of genus.

Two Cypretta species from Thailand are described: Cypretta aculeata n. sp. and Cypretta triangulata n. sp. Cypretta        aculeata n. sp. can be characterized chiefly by the valve surface equipped with long setae, spine-like bristle and distinctive pits, the presence of tubercles on postero-ventral margin of the internal left valve and the denticulated ridge on the postero-ventral part of the internal right valve, the long d1 seta on the second thoracopod (T2), and the long Sp seta on the caudal ramus (CR). Based on the valve surface ornamentation, C. aculeata n. sp. is similar to C. globosa (Brady, 1886), C.            intonsa Furtos, 1936, C. spinosa Cohuo-Durán et al., 2013 and C. vivacis Würdig Pinto 1993. A key to the species within this group is thus provided. The main diagnostic features of Cypretta triangulata n. sp. are the triangular carapace in the dorsal view, the absence of tubercles on the postero-ventral margin of the internal left valve, the presence of denticulated ridge on the postero-ventral part of the internal right valve, the short d1 seta on T2 and the long Sp seta on the CR. The diagnostic characters for the species identification of the genus Cypretta are briefly discussed with regard to the morphology and number of the septa and lunules, the traits of the internal side of the valves, the features of soft body parts (such as the mandible, the thoracopods and the CR) and the morphological aspects of the hemipenis.

Species diversity of ostracods (Crustacea: Ostracoda) from rice fields in Northeast Thailand, with the description of a new Tanycypris species.

The species diversity of ostracods in rice fields from Northeast Thailand was studied. Fifty-two samples were collected from 43 rice fields during 2010-2016. This investigation revealed 23 genera and 52 species, including one new to science (Tanycypris eugenkempfi n. sp.) and 21 endemic species: endemic to the Oriental region (14 species), Southeast Asia (two species) and Thailand (five species). In addition, two species that were restricted to rice fields in this study were recognized: Bradleytriebella tuberculata (Hartmann, 1964) and Notodromas sinensis Neale & Zhao, 1991. The most diverse genus was Pseudostrandesia, followed by Strandesia with eight and five species, respectively. The most widely distributed species were Pseudocypretta maculata Klie, 1932 and Strandesia kraepelini (G.W. Müller, 1906) occurring in 48.8 % of the total of surveyed rice fields. The number of species in individual rice fields ranged from none to 18. Most of the samples contained three species, but one rice field showed very high species richness (18 species). Most of the species recorded in this study were also found in several types of water bodies and reported from several zoogeographical regions. The main distinguishing characters between Tanycypris eugenkempfi n. sp. and other Tanycypris species are the more tumid carapace in dorsal view, the distinctly arched dorsal margin of the carapace in lateral view, the presence of a subapical dorsal seta on the first segment of the first antenna, the smooth large bristles on the third endite of the maxillula, the absence of c-seta on the first thoracopod, and the long proximal claw (Gp) of the caudal ramus.

A new genus and four new species of subfamily Cyclocypridinae (Crustacea, Ostracoda) from Thailand.

A new genus, Dentocypria n. gen., in the subfamily Cyclocypridinae Kaufmann, 1900 is described from Thailand. The main distinguishing characters of the new genus are the presence of an internal tooth on the antero-ventral part of the left valve, the marginal tubercles on the right valve, the very elongated terminal segment of the madibular palp, the absence of setae on the basal segment of the second thoracopod (T2), the unusually long e-seta of T2, the short terminal segment of the third thoracopod (T3), the long Sp seta of the caudal ramus and the morphology of prehensile palps and hemipenis. Four new species of the new genus are here described: Dentocypria mesquitai n. gen. n. sp., Dentocypria chantaranothaii n. gen. n. sp., Dentocypria smithi n. gen. n. sp. and Dentocypria aequiloba n. gen. n. sp. A brief discussion on the generic characters and a key to the genera of the subfamily are provided.

A checklist of Recent non-marine ostracods (Crustacea: Ostracoda) from Thailand, including descriptions of two new species.

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.

On three new species of non-marine ostracods (Crustacea: Ostracoda) from Northeast Thailand.

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.

Ostracods (Crustacea: Ostracoda) from the floodplain of the Chi River, Mahasarakham Province, Northeast Thailand, with the first record of male Tanycypris siamensis Savatenalinton & Martens, 2009.

The species diversity of ostracods in the floodplain of the Chi River basin, Mahasarakham Province, Northeast Thailand was examined in this study. Twenty-two samples were collected in the cool season (February 2010). Twenty-six species belonging to 18 genera were recorded, three of which are new to the Oriental region (Fabaeformiscandona subacuta (Yang, 1982), Ilyocypris monstrifica (Norman, 1862) and Limnocythere stationis Vávra, 1891) and one (Hemicypris ovata Sars, 1903) is a new record for Thailand. The most common species were Strandesia kraepelini (G.W. Müller, 1906) and Physocypria crenulata (Sars, 1903) occurring in 77% and 64% of the sampled localities, respectively. Additionally, males of Tanycypris siamensis Savatenalinton & Martens, 2009 were found and are here described for the first time. This discovery shows that the morphology of the hemipenis and of the Zenker organs of T. siamensis is similar to that of species in the genus Cypricercus. Additional comments on chorology and ecology of several taxa are also given. 

On Callistocypris thailandensis sp. nov. (Ostracoda, Crustacea) from Thailand.

Callistocypris thailandensis sp. nov. is here described from terrestrial habitat in Khao Yai National Park, Nakhon Ratchasima province, Thailand. The new species differs from the other three Callistocypris species in the shape of carapace, the presence of strong longitudinal ridges on the ventral part of the valves and the chaetotaxy of several limbs. Zoogeography and ecology of the genus are briefly discussed.