La-orsri Sanoamuang

Additions to the rotifer fauna of south-east Asia: new and rare species from north-east Thailand

Ninety-three freshwater habitats in the north-eastern part of Thailand were surveyed for rotifers during March–October 1993. Two hundred species were identified, 120 of which are new to Thailand. Brachionus africanuss Segers, B. lyratus Shephard and Trichocerca hollaerti De Smet are new to Asia. Brachionus niwati n.sp. is described and figured. Brachionus donneri Brehm, Keratella edmondsoni (Ahlstrom) and Lecane blachei Berziņš, endemic to south and southeast Asia, were found also.Comments are presented on some insufficiently known taxa. Of special zoogeographic interest is the record of several species previously considered endemic to Australia. An attempt is made to characterise the Thai rotifer fauna in the light of recent developments in rotifer zoogeography.

First record of the family Thamnocephalidae (Crustacea: Anostraca) from Southeast Asia and description of a new species of Branchinella

During a two-year investigation of freshwater microcrustaceans in Thailand, an undescribed species of fairy shrimp of the genus Branchinella Sayce, 1903 in the family Thamnocephalidae, was discovered. This is the first record of the genus and the family from Southeast Asia and the second anostracan reported from Thailand. The new species, Branchinella thailandensis n. sp. appears to be morphologically intermediate between B. kugenumaensis (Ishikawa, 1895) from Japan and east China, and B. madurai Raj, 1951 from India and Pakistan. B. thailandensis n. sp. was collected from several temporary ponds in 11 provinces of the northeast and the central Thailand, often co-occurring with Streptocephalus sirindhornae Sanoamuang, Murugan, Weekers & Dumont, 2000.

Contributions to the knowledge of the Cladocera of north-east Thailand

Examination of 200 samples from 93 freshwater habitats in north-eastThailand revealed 60 taxa of Cladocera, of which 31 are new to the Thaifauna. Six species (Disparalona caudata Smirnov; Leydigialaevis Gurney; Leydigiopsis sp.; Macrothrix flabelligeraSmirnov; Macrothrix cf. paulensis Sars; and Pseudosidaramosa Daday) are new to Asia. The majority of the Cladocera recorded arecircumtropical species. Comments and figures are presented on several ofthe new records for Asia and Thailand.

Rotifera of some freshwater habitats in the floodplain of the River Nan, northern Thailand

A survey of 11 freshwater habitats in the floodplain of the River Nan, northern Thailand was carried out during April and September 1996. The rotifer samples were collected qualitatively from paddy fields, ponds, canals and reservoirs, using a 60 μm mesh net. One hundred and eighteen species were identified, four (Lepadella quinquecostata (Lucks), Macrochaetus danneeli Koste & Shiel, Testudinella ahlstromi Hauer and T greeni Koste) of which are new to Thailand and one (L. quinquecostata) is new to Asia. The numbers of species found in two localities are relatively high, with 86 and 73 rotifer taxa. Most of the species recorded are common, cosmopolitan or pantropical and warm-stenotherms. The occurrence of a species previously considered endemic to Australia, M. danneeli provides more evidence illustrating a relation between the rotifer faunas of southeast Asia and Australia. Comments are presented on some insufficiently known taxa in particular on the new records for Thailand.

The rotifer fauna of Lake Kud-Thing, a shallow lake in Nong Khai Province, northeast Thailand

The species composition of the rotifer fauna of Lake Kud-Thing, Nong Khai Province, northeast Thailand was investigated in a monthly sampling program from January to December 1998. A remarkably rich rotifer community consisting of 183 taxa was recorded, including 32 new records to the Thai fauna. The most diverse genera were Lecane (23.5%), followed by Trichocerca (16.9%) and Lepadella (11.5%). Lecane isanensis n. sp. is described and figured. Thirteen species (Aspelta circinator, Collotheca tenuilobata, Lecane nelsoni, Lepadella benjamini, Lepadella eurysterna, Sinantherina ariprepes, Testudinella cf. insinuata, Trichocerca abilioi, Trichocerca inermis, Trichocerca montana, Trichocerca orca, Trichocerca rosea and Trichocerca simonei) are new to the Oriental region. Notably, the record of Trichocerca orca is the first since its discovery in New Zealand in 1913. The rotifers can be classified into three groups based on duration of appearance; (1) common, perennial; (2) uncommon, perennial; and (3) uncommon, sporadic species. The high species richness of rotifers, particularly members of the genera Lecane and Trichocerca, but low diversity of Brachionus together suggest that the lake is probably not eutrophicated.

Life History of Three Fairy Shrimps (Branchiopoda: Anostraca) from Thailand

Abstract Life table characteristics of three species of fairy shrimps from Thailand, Streptocephalus sirindhornae, S. siamensis, and Branchinella thailandensis are reported, based on laboratory cultures at 24-26°C. Comparative data on their growth and fecundity revealed that B. thailandensis had the largest size (male 26.2, female 27.8 mm) and the highest hatchability 87.67%. The shortest hatching time was found in B. thailandensis, it hatched within 3 days, while the other two species hatched within four days. Branchinella thailandensis showed more rapid growth than the other two species, and it reached maturity within 6.5 days. In contrast, S. sirindhornae had the highest fecundity, producing a mean of 35.3 broods and 17,865 eggs per individual female over its life time, whereas the other two species produced less than 8000 eggs. Life span was equal for both males and females in all three fairy shrimp species (P > 0.05). In this study, the fecundity data indicated that the number of eggs per brood recorded in the three species showed a positive correlation with the body length and age of females. The result indicated that the Thai fairy shrimps show several biological attributes making them suitable for aquaculture and other commercial purposes; B. thailandensis shows rapid growth and high hatching percentage which is suitable for mass production, while S. sirindhornae has high fecundity which is appropriate for the commercial production of eggs.

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.

Biochemical Composition of Three Species of Fairy Shrimp (Branchiopoda: Anostraca) from Thailand

ABSTRACT Biochemical profiles and proximate analysis of three species of fairy shrimps from Thailand, Streptocephalus sirindhornae, S. siamensis, and Branchinella thailandensis are characterized and compared. The nutritional analysis reveals that all three species contain high protein levels, particularly essential amino acids that are needed for growth and reproduction. Streptocephalus sirindhornae contains significantly higher crude protein (74.41%) than B. thailandensis (64.65%) and S. siamensis (50.24%). The highest percent of crude lipid (9.34%) and carbohydrate (32.69%) contents are found in S. siamensis. The highest amino acid content is recorded in S. sirindhornae (784.92 mg g-1 dw) followed by that of B. thailandensis (596.12 mg g-1 dw) and S. siamensis (439.58 mg g-1 dw). Predominant amino acids found in all three species are lysine, phenylalanine, leucine, tyrosine, and glutamic acid. For fatty acids, palmitic acid C16:0, oleic acid C18:1n9, stearic acid C18:0, linolenic acid C18:3n3, and linoleic acid C18:2n6 are found to be major components. Branchinella thailandensis has the highest carotenoid content of 254.41 µg g-1, followed by S. siamensis (211.92 µg g-1) and S. sirindhornae (128.93 µg g-1). Carotenoid content analysis show the presence of dominant groups consisting of &bgr;-carotene, canthaxanthin, astaxanthin, and lutein. The presence of essential fatty acids, amino acids, and carotenoids is the principal factor that determines the food value of Thai fairy shrimps for aquaculture application. These biochemical attributes make these Thai fairy shrimps ideal as feed for aquaculture.

Biodiversity of freshwater microfauna in the floodplain of the River Mun, Northeast Thailand: the Rotifera monogononta

We report on the γ- diversity of Rotifera in freshwater habitats of the River Mun floodplain, Northeast Thailand. Qualitative samples were collected during the pre-monsoon (April) and post-monsoon (October) periods of 2000, from 70 habitats spanning a diverse array of freshwater habitat types. Of the 184 species identified, most belong to Lecane (31.0%), followed by Trichocerca (12.0%), Lepadella (11.4%) and Brachionus (8.2%). Oriental, Australasian, and Eastern hemisphere taxa account for 4.3%, 3.3% and 7.1%, respectively, of the total rotifer fauna, and 8.8%, 1.7% and 10.5%, respectively, of Lecane. Although comparison between studies is difficult, these numbers conform to previous reports on the diversity and composition of the rotifer fauna of Thai freshwater habitats, and of tropical floodplain ecosystems. Diversity is lowest during the post-monsoon period, which may result from disturbance by monsoon conditions. Two morphospecies, Brachionus srisumonaen. sp., and Lecane niwati n. sp., are described as new to science. Additional noteworthy occurrences are, Lecane robertsonae Segers, previously considered a Neotropical endemic, and L. subtilis Harring & Myers, a tropicopolitan species new to Thailand and the Oriental region.

New records of rotifers from Nakhon Ratchasima province, northeast Thailand, with a description of Lecane baimaii n. sp

The rotifer fauna of 77 freshwater habitats in Nakhon Ratchasima province, northeast Thailand, was studied. Lecane baimaii n.sp. is described and figured. The new species occurs in Thailand as well as Nigeria. Eleven species (Lecane decipiens (Murray), Lecane serrata (Hauer), Lecane thienemanni (Hauer), Lecane donneri Chengalath & Mulamoottil, Lecane grandis (Murray), Lecane punctata (Murray), Lepadella akrobeles Myers, Lepadella elongata Koste, Scaridium elegans Segers & De Meester, Trichocerca porcellus (Gosse) and Wolga spinifera Western) are new to Thailand. Comments and figures are presented on the new records for Thailand.