Estimation of density of gibbon groups by use of loud songs

The density of gibbon populations may be estimated by listening for the loud duetted songs of monogamous territorial groups. This method requires a correction factor which must be estimated from the frequency of singing of an adequate number of known study groups. The correction factor and its error were estimated for pileated gibbons (Hylobates pileatus) in Khao Soi Dao Wildlife Sanctuary in southeastern Thailand. Among 30 groups studied, 47% sang per day, on average, but the variation between days and the variation in singing frequency between groups were large. Weather conditions, especially windiness, explained some variation in singing. During an area-wide survey of groups in the sanctuary, unexplained variation in singing from day to day accounted for approximately half of the sample error of group density estimated from 1-day listening samples. Error due to day-to-day variability can be reduced by listening for more than one day at each site. Correction factors based on the cumulative proportion of groups heard during longer (2–5-day) sample periods of listening were closer to 1.0, therefore leaving less room for error and bias of the correction factor. © 1993 Wiley-Liss, Inc.     

Diversity of Anopheles species and trophic behavior of putative malaria vectors in two malaria endemic areas of northwestern Thailand

We determined the species diversity, blood‐feeding behavior, and host preference of Anopheles mosquitoes in two malaria endemic areas of Tak (Mae Sot District) and Mae Hong Son (Sop Moei District) Provinces, located along the Thai border with Myanmar, during a consecutive two‐year period. Anopheline mosquitoes were collected using indoor and outdoor human‐landing captures and outdoor cow‐baited collections. Mosquitoes were initially identified using morphological characters, followed by the appropriate multiplex AS‐PCR assay for the identification of sibling species within Anopheles (Cellia) complexes and groups present. Real‐time PCR was performed for parasite‐specific detection in mosquitoes (Plasmodium spp. and Wuchereria bancrofti). A total of 7,129 Anopheles females were captured, 3,939 from Mae Sot and 3,190 from Sop Moei, with 58.6% and 37% of all anophelines identified as An. minimus, respectively. All three malaria vector complexes were detected in both areas. One species within the Minimus Complex (An. minimus) was present along with two related species in the Funestus Group, (An. aconitus, An. varuna), two species within the Dirus Complex (An. dirus, An. baimaii), and four species within the Maculatus Group (An. maculatus, An. sawadwongporni, An. pseudowillmori, and An. dravidicus). The trophic behavior of An. minimus, An. dirus, An. baimaii, An. maculatus, and An. sawadwongporni are described herein. The highest An. minimus densities were detected from February through April of both years. One specimen of An. minimus from Mae Sot was found positive for Plasmodium vivax.     

Population structure, recruitment, and succession of the brown alga, Padina boryana Thivy (Dictyotales, Heterokontophyta), at an exposed shore of Sirinart National Park and a sheltered area of Tang Khen Bay, Phuket Province, Thailand

The brown algal genus, Padina, has a worldwide distribution in tropical and subtropical climate zones. Padina individuals are common and sometimes dominant in both the intertidal and shallow subtidal regions associated with coral reefs. We investigated the population structure and recruitment of two populations of Padina boryana at an exposed shore in Sirinart National Park (SNP) and a sheltered shore of Tang Khen Bay (TKB), Phuket Province, Thailand. From September 2005 to August 2006, the number of released spores and the height and radius of fronds were measured monthly. New recruits were recorded and monitored on manipulated permanent plots 0.25 m². The experiment was carried out monthly over a year. We found Padina recruits 1 month after the plots were cleared at both sites. There was a significant difference in percentage cover by new individuals between the two locations (P < 0.05) and also at the shore levels within the sites. At SNP, the highest recruitment was found in the uppermost zone, while at TKB high recruitment occurred at all shore levels except at 80-100 m from the shore. The factors influencing recruitment of P. boryana include wave motion, competition with other earlier successional species and sediment. The high availability of reproductive spores throughout the year, the successful recruitment and the Dictyerpa stage promote the successful establishment of Padina populations.     

Morphological characteristics in relation to diet in five coexisting Thai fish species

Morphological characteristics and intestinal content were analysed for five species of coexisting freshwater fishes in Thailand: Rasbora caudimaculata , Schistura desmotes , Dermogenys pusillus , Xenentodon cancila and Monopterus albus (all found in riffle habitats in Thai streams). Rasbora caudimaculata , S. desmotes and D. pusillus fed predominantly on ephemeropterans, hymenopterans and dipterans, X. cancila fed predominantly on fishes, and larger aquatic invertebrates such as Odonata, and M. albus fed on detritus as well as invertebrate prey such as crustaceans and Odonata. Intestine length, mouth height, mouth width, eye position and mouth orientation varied among all five species. Canonical analysis of discriminance of mouth height, width and intestine length showed a clear dispersion of species, which was supported by intestine content. Evolutionary processes leading to the present differences in morphological characters resulted in each of the five species consuming a different portion of the available resource base, thereby facilitating coexistence.     

Permian and Triassic Radiolaria from Northwest Thailand: paleogeographical implications

Well-preserved radiolarians were recovered from seven sections in the Mae Hong Son-Mae Sariang area, northwestern Thailand. 51 species assigned to 34 genera are identified, including 1 new species (Triassospongosphaera erici Feng sp. nov.) and 19 unidentified species. They are divided into the Late Permian, late Ladinian and middle Carnian radiolarian assemblages. Newly identified radiolarian assemblages, together with the published radiolarian biostratigraphic data from this region, indicate that there was a pelagic basin during the Late Paleozoic and Triassic. This basin was joined to the Chiang Dao and Changning-Menglian oceanic basins, and they represent the main oceanic basin of the Paleotethyan Archipelago Ocean. This main oceanic basin was situated in the traditional “Shan-Thai Block”. Therefore, “the Shan-Thai Block” was not a single block during that stage, but composed of the Paleotethyan Ocean and two continental terranes that were affiliated with the Gondwana and Cathaysian domains, respectively.     

Morphological and Molecular Characterization of a New Root-Knot Nematode,Meloidogyne thailandica n. sp. (Nematoda: Meloidogynidae), Parasitizing Ginger (Zingiber sp.)

A root-knot nematode Meloidogyne thailandica n. sp. was discovered on roots of ginger (Zingiber spp.) intercepted from Thailand in October 2002 by the U.S. Department of Agriculture Animal and Plant Health Inspection Service at the port of San Francisco. Comparison by light microscopy (LM) and scanning electron microscopy (SEM) to five other morphologically related species (M. incognita, M. arenaria, M. microcephala, M. megatyla, and M. enterolobii) revealed that the new species differs from these by one or more of the following: body, tail and hyaline tail length, shape of head, tail and tail terminus of second-stage juveniles; stylet length and shape of spicules in males; perineal pattern, stylet length and shape of knobs in females. The distinctive perineal pattern is oval to rectangular, with smooth to moderately wavy and coarse striae, and with characteristic radial structures present underneath the pattern area; the dorsal arch is high, sometimes round to rectangular, and striae in and around the anal area form a thick network-like pattern interrupted by lateral lines and large phasmids. Second-stage juveniles have a long, slender tail and long, gradually tapering hyaline tail region ending in a rounded terminus. Male spicules commonly have an acutely angled shaft with a bidentate terminus. Molecular data from the ribosomal large subunit D3 expansion segment revealed four haplotypes, two of which were unique and distinguish M. thailandica n. sp. from M. arenaria, M. incognita, and M. javanica.     

Trichosporon siamense sp. nov. isolated from insect frass in Thailand

A strain of yeast isolated from insect frass collected in Thailand was found to represent a hitherto undescribed species of a basidiomycetous anamorphic genus Trichosporon. It is described as Trichosporon siamense. In the phylogenetic tree based on the D1/D2 region sequences of 26S rDNA, this yeast constitutes a cluster with several Q-9 having species of Trichosporon including T. otae and T. brassicae but is clearly differentiated from these species by 1.8% or more base substitutions. In the internal transcribed spacer region (ITS1 and ITS2), this species differs from T. scarabaeorum, the nearest species, by 6.5% base substitution.     

Histopathological Changes in Tissues of Bithynia siamensis goniomphalos Incubated in Crude Extracts of Camellia Seed and Mangosteen Pericarp

The present study was performed to observe histopathological changes in tissues of Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) incubated in crude extract solutions of camellia (Camellia oleifera) seed and mangosteen (Garcinia mangostana) pericarp, and furthermore to estimate the molluscicidal effects of 2 plant substances. Substantial numbers of bithyniid snails were incubated in various concentrations of 2 plant solution for 24 hr. As the positive control, snails incubated in various concentrations of niclosamide, a chemical molluscicide, were used. The histopathological findings were observed in sectioned snail specimens of each experimental and control groups. The results showed that both camellia and mangosteen extracts had molluscicidal effects at 24 hr with 50% lethal concentration (LC₅₀) at concentrations of 0.003 and 0.002 g/ml, respectively, while niclosamide had LC₅₀ at concentrations 0.599 ppm. B. siamensis goniomphalos snail tissues (foot, gill, and digestive system) showed disruption of columnar muscle fibers of the foot, reduction of the length and number of gill cilia, numerous mucous vacuoles, and irregularly shaped of epithelial cells. Irregular apical and calciferous cells, dilatation of the digestive gland tubule, and large hemolymphatic spaces, and irregular apical surfaces, detachment of cilia, and enlargement of lysosomal vacuoles of epidermis were also shown in all groups. By the present study, it is confirmed that 2 plants, camellia and mangosteen, are keeping some substance having molluscicidal effects, and histopathological findings obtained in this study will provide some clues in further studies on their action mechanisms to use them as natural molluscicides.     

Long-tailed macaques select mass of stone tools according to food type

Tool selection can affect the success of a tool-based feeding task, and thus tool-using animals should select appropriate tools when processing foods. We performed a field experiment on Piak Nam Yai Island in Laem Son National Park, Thailand, to test whether Burmese long-tailed macaques (Macaca fascicularis aurea) selected stone tools according to food type. We baited the island''s shores with stone sets (‘tool tests’) in an effort to attract macaques to use stones presented in a quasi-experimental design. Tool tests were placed at 344 locations for 126 days over a 2 year period, with each set containing four stones of different mass (categories: X, 40–60 g; S, 90–100 g; M, 150–200 g; and L, 400–1000 g). Tool tests were checked when we could access them. The number of times each tool test was checked varied (1–32), for a total of 1950 checks. We also studied 375 non-experimental stone tools that were found at naturally occurring tool-use sites. Our data were not collected by direct observation, but by inspecting stones after use. We found an association between stone mass and food type. In the tool tests, we found S-stones were chosen most often for attached oysters, and L-stones were chosen most often for unattached foods. L-stones were almost always chosen for larger unattached foods (greater than 3 cm length), while for smaller unattached foods (less than or equal to 3 cm length) selection was less skewed to L-stones and more evenly distributed between the M- and L-stone categories. In the non-experimental study, we found that mass varied significantly across five food categories (range: 16–5166 g). We reveal more detail on macaque stone tool mass than previous studies, showing that macaques select differing stone masses across a variety of tool-processed foods. Our study is the first step in investigating the behavioural and cognitive mechanisms that macaques are using during tool selection.