The cyst hatching pattern of the Thai fairy shrimp, Branchinella Thailandensis Sanoamuang, Saengphan & Murugan, 2002 (Anostraca)

We investigated factors influencing the hatching of the fairy shrimp, Branchinella thailandensis in relation to brood order, and also responses of cysts to wet and dry periods. Male-female pairs of B. thailandensis were cultured under static conditions at room temperature and fed ad libitum micro-algae (Chlorella sp.). Deposited cysts of the first, sixth and eleventh broods were monitored for cyst hatching under wet and dry conditions. Cyst hatching was scored daily for 5 days after incubation. Freshly laid cysts, immediately incubated, did not hatch in any of the experimental conditions (wet/dry). On the contrary, undried cysts immersed in their parental medium for 4 weeks showed the highest hatching in all brood treatments (76.67, 94.67, and 99.33% of the first, sixth, and eleventh broods, respectively). The cysts of the first brood hatched less successfully than did those of the sixth and eleventh broods. Cyst hatching mostly took place within 24 hours after incubation. The present study shows that a wet period has a strong influence on the cyst hatching success of B. thailandensis. The cysts require a period of retention in the parental medium for 2-4 weeks to complete their embryonic development before hatching. Hatching of the three representative broods showed a different pattern for each brood. The early broods required a longer wet period than did the late broods. In contrast to the hatching behaviour of many other species, drying is not absolutely essential for cyst hatching of this species. © Koninklijke Brill NV, 2005

A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

Copyright © 2019 Magnolia Press. A new species of Moina Baird, 1850 (Cladocera: Moinidae) is described based on material collected from Thailand (South-East Asia). In tropical Asia, Moina siamensis sp. nov. could be confused easily with M. weismanni Ishikawa, 1896, because of morphological similarities in parthenogenetic females and males of both species. The outstanding difference between these two taxa concerns the structure of the ephippium in gamogenetic females, which is highly visible under light and scanning electron microscopes. The mature ephippium of M. weismanni is strongly tuberous, with distinct borders between cells, whereas the ephippium of M. siamensis sp. nov. is significantly less tuberous, with prominent longitudinal lines in its central region. Since gamogenetic females only appear sporadically in moinid populations, distribution ranges of M. siamensis sp. nov., M. weismanni and sibling taxa must be clarified precisely using genetic markers in the future. Preliminary investigations of the ephippium structure may be useful for estimating the differences between populations, thus revealing much diversity within Moinidae

A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

Copyright © 2019 Magnolia Press. A new species of Moina Baird, 1850 (Cladocera: Moinidae) is described based on material collected from Thailand (South-East Asia). In tropical Asia, Moina siamensis sp. nov. could be confused easily with M. weismanni Ishikawa, 1896, because of morphological similarities in parthenogenetic females and males of both species. The outstanding difference between these two taxa concerns the structure of the ephippium in gamogenetic females, which is highly visible under light and scanning electron microscopes. The mature ephippium of M. weismanni is strongly tuberous, with distinct borders between cells, whereas the ephippium of M. siamensis sp. nov. is significantly less tuberous, with prominent longitudinal lines in its central region. Since gamogenetic females only appear sporadically in moinid populations, distribution ranges of M. siamensis sp. nov., M. weismanni and sibling taxa must be clarified precisely using genetic markers in the future. Preliminary investigations of the ephippium structure may be useful for estimating the differences between populations, thus revealing much diversity within Moinidae

FIGURE 5 in A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

FIGURE 5. Moina siamensis sp. nov., adult parthenogenetic female (paratype, MGU Ml 166; A–B, E–H) and ephippial female (paratype, MGU Ml 168; C–D) from a roadside temporary pond in Nong Yasai district, Suphan Buri province, Thailand, coll. 26.04.07, N. Saengphan. A, adult parthenogenetic female, lateral view. B, parthenogenetic female, ventral view. C, ephippium, lateral view. D, ephippium, dorsal view. E–F, postabdomen. G, head, ventral view. H, antenna I. Scale bars 0.1 mm

FIGURE 9 in A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

FIGURE 9. Moina siamensis sp. nov., adult male (paratype, MGU Ml 167) from a roadside temporary pond in Nong Yasai district, Suphan Buri province, Thailand, coll. 26.04.07, N. Saengphan. A–B, lateral view. C, anteroventral portion of male. D– E, antenna I. Scale bars 0.1 mm for A–C; 0.05 mm for D–E

FIGURE 4 in A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

FIGURE 4. Moina siamensis sp. nov., ephippium (paratype, MGU Ml 168) from a roadside, temporary pond in Nong Yasai district, Suphan Buri province, Thailand, coll. 26.04.07, N. Saengphan. A, lateral view. B, ephippial cells. Scale bars 0.2 mm for A; 0.02 mm for B

FIGURE 3 in A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

FIGURE 3. Moina siamensis sp. nov., mature ephippial female (paratype, MGU Ml 168; A–D) and adult male (paratype, MGU Ml 167; E–J) from a roadside temporary pond in Nong Yasai district, Suphan Buri province, Thailand, coll. 26.04.07, N. Saengphan. A, ephippial female, lateral view. B, ephippium, lateral view. C, ephippium, dorsal view. D, ephippial cells. E, male, lateral view. F, valve. G, postabdomen. H, antenna I. I–J, limb I. Scale bars 0.1 mm for A–C, E–J; 0.01 mm for D

Emergent effects of light and temperature on hatching success of Streptocephalus cafer (Branchiopoda: Anostraca) resting eggs

Resting egg production is considered the most common form of dormancy in aquatic invertebrates. Given that many taxa at least partially terminate resting egg state using environmental cues, knowledge on environmental drivers of hatching success is important, particularly within the context of climate change and environmental degradation. Fairy shrimp (anostracans) are temporary wetland specialists that are reliant on resting egg production for population persistence. Temporary wetlands are common in many arid regions projected to experience increases in temperature, and in areas often compromised by human‐mediated activities. In this study, we assessed the combined effects of light and temperature on the hatching success of Streptocephalus cafer (Anostraca) dormant eggs from temporary wetlands in an arid environment. Both temperature and light altered hatching success, with emergent effects evident. Light caused a significant threefold increase in hatching success overall, while temperature effects were non‐linear, with hatching optimised at 27°C, and especially under light conditions. These results are discussed within the context of shifting climates and disturbances to temporary wetland ecosystems