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Two new species of Aricidea (Aricidea) (Annelida: Paraonidae) from the Andaman coast and the Gulf of Thailand
(2026-07-03)
Plathong, Jintana
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Plathong, Sakanan
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Klangnurak, Wanlada
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Ranauro, Natalia
;
Hernández-Alcantara, Pablo
Two new species of Paraonidae, Aricidea (Aricidea) pacharaphoni sp. nov., and A. (A.) sathingpra sp. nov., are described from the Southwestern Pacific. Aricidea (A.) pacharaphoni sp. nov., collected in the Andaman Coast and the Gulf of Thailand, is clearly distinguished from other species of Aricidea (Aricidea) by having an elongate, faintly annulated median antenna extending to chaetigers 3–7; chaetiger 3 with distinctive globose notopodial postchaetal lobes with long digitiform terminal tips; two types of branchiae, strap-like and foliaceous; and two types of modified neurochaetae, pseudocompound and stout acicular. Aricidea (A.) sathingpra sp. nov., was collected in the Gulf of Thailand and belongs to the articulated antenna group, being separated from all other species of this subgenus by having a triarticulated antenna; pair of distinctive round furrow protuberances on the prostomium; and 6–7 pairs of wide foliaceous branchiae. We suggested that the modification and shape of the notopodial postchaetal lobes in chaetiger 3 are an important morphological character to differentiate the species of this subgenus. Molecular phylogenetic and genetic distance analyses, based on cytochrome oxidase subunit I (COI) gene sequences support the recognition of Aricidea (A.) pacharaphoni sp. nov., as a distinct species. A taxonomic key for all world species of Aricidea (Aricidea) is included.
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Unveiling the species in shark-based pet snack products with an overview of e-commerce trends
(2026-01-01)
Klangnurak, Wanlada
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Arunrugstichai, Sirachai
;
Manopawitr, Petch
Shark cartilage and whole-dried small sharks are increasingly being used in Thailand's pet snack market, raising sustainability concerns. This study examined the issues by identifying shark species in cartilage and whole-dried shark products used in pet snacks and analyzing online market trends. A total of 150 shark cartilage and 60 whole-dried shark samples were analyzed using DNA barcoding. Notably, 91 % of the cartilage products were identifiable at the species level, with eight shark species represented. The brown-banded bamboo shark (Chiloscyllium punctatum) and the Australian blackspot shark (Carcharhinus coatesi) were the most common, making up 63.2 % of samples. Of the identified species, 61.8 % are classified as Near Threatened on the IUCN Red List, and 67.7 % are from species listed in CITES Appendix II. All whole-dried sharks were Scoliodon macrorhynchos, also classified as Near Threatened and CITES-listed. Shark cartilage products dominated the market, appearing in 62–65 % of shops, compared to 35–38 % for whole-dried sharks. The findings emphasize the need to strengthen the monitoring and enforcement of CITES-listed sharks, improve traceability and transparency in the supply chain, and regulate the online market for shark-based pet snacks.
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ANEMONE Global's First eDNA-Based Assessment: Insights Toward a Standardized Global Monitoring Network
(2026-01-01)
Sioud, Imane
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Minegishi, Yuki
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Kajita, Tadashi
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Isowa, Yukinobu
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Tanabe, Akifumi S.
Environmental DNA (eDNA) enables sensitive detection of species from environmental samples, particularly water. Large-scale, standardized monitoring of coastal fish communities remains challenging across diverse regions. The ANEMONE Global network was established to address this gap, expanding the workflow developed in Japan to a coordinated worldwide survey using standardized eDNA metabarcoding. Between June and November 2024, 12 countries, including several in Southeast Asia, collected surface water samples from beaches, rocky shores, estuaries, and near coastal protective structures using harmonized protocols for filtration, RNAlater preservation, and metadata recording. Daytime and nighttime sampling captured temporal variation in community composition. All samples were processed with the MiFish metabarcoding protocol, quantitative internal standards, and rigorous contamination controls. Analysis of 90 samples generated over 16.6 million high-quality reads, revealing more than 500 putative fish OTUs across diverse families, genera, and species. Species richness varied geographically, reflecting differences in fish fauna, and assemblages differed across the Atlantic, Indian, North Pacific, and South Pacific Oceans. Diel variation was most pronounced in the North Pacific, and diversity patterns reflected both habitat complexity and ocean basin, with waters adjacent to coastal protective structures and rocky shores supporting the highest diversity. These findings highlight how both habitat complexity and ocean basin geography shape coastal fish assemblages, offering insights for global marine biodiversity monitoring using eDNA. This survey demonstrates that a globally standardized eDNA workflow can generate comparable quality data across ecological and logistical contexts. By combining international collaboration, open data, and locally informed implementation, ANEMONE Global provides a framework for long-term, high-resolution monitoring of coastal biodiversity and sets the stage for expanding coverage to additional aquatic ecosystems worldwide.
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Morphological and molecular insights into diversity of Brevitrygon (Elasmobranchii, Myliobatiformes, Dasyatidae) in Thai waters
(2026-01-01)
Wongmanee, Phiphat
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Khudamrongsawat, Jenjit
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Krajangdara, Tassapon
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Senanan, Wansuk
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Panithanarak, Thadsin
Stingrays of the genus Brevitrygon in Thailand are captured as bycatch in fisheries, and a proportion of the catch is used for local consumption, but information on their biodiversity remains limited. This study examines the diversity of Brevitrygon species collected from the Gulf of Thailand and the Andaman Sea. A total of 148 specimens were morphologically identified as either Brevitrygon heterura (Bleeker, 1852) or Brevitrygon cf. imbricata, based on diagnostic characters. Morphometric analysis revealed that all specimens more closely resembled B. heterura, with no significant differences between morphotypes or sexes. Genetic analysis based on COI sequences from 39 samples further supported these results. All samples grouped within the B. heterura clade with strong bootstrap support and formed two distinct genetic subgroups corresponding tothe Gulf of Thailand and the Andaman Sea. The mean intraspecific divergence (1.08%) fell within the expected range for population-level variation in elasmobranchs, with interspecific divergence from other Brevitrygon species exceeding 9%. These results indicate that B. heterura in Thai waters likely represents a single species. While both morphometric and genetic data suggest regional differentiation, the observed variation falls within the normal range for a single species, providing no evidence of cryptic diversity. This study underscores the value of integrating morphological and molecular data to better understand population structure and taxonomy in stingrays.
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Four new species of Fauveliopsidae (Annelida, Sedentaria) from the Gulf of Thailand
(2026-01-01)
Plathong, Jintana
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Plathong, Sakanan
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Klangnurak, Wanlada
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Salazar-Vallejo, Sergio I.
Four new species of Fauveliopsidae, Fauveliopsis pladang sp. nov., Laubieriopsis tantawan sp. nov., Riseriopsis chaba sp. nov., and R. plahmuk sp. nov., are described from the Gulf of Thailand from sediments at 50–80 m water depth. Fauveliopsis pladang sp. nov., can be distinguished from other species by having 41 chaetigers; anterior parapodia with two acicula chaetae per bundle; in median and posterior segments 1 aciculum and 1 capillary per bundle. Laubieriopsis tantawan sp. nov., differs from all other species in the genus by having 27–43 chaetigers, body annulate; 2 acicula per bundle in anterior parapodia; in median and posterior parapodia with 1 aciculum and 1 capillary per bundle. Riseriopsis chaba sp. nov., can be distinguished from other species by having 34 chaetigers; anterior parapodia with 2 acicula per bundle; median and posterior notopodia with one aciculum and one capillary per bundle; median neuropodia with 1 aciculum and 2 capillaries per bundle; posterior neuropodia with 1–2 acicula and 1 capillary per bundle. Riseriopsis plahmuk sp. nov., can be distinguished from other species by having 2–4 acicula per bundle along anterior segments; median segments with 1–2 acicula and 1–2 capillaries per bundle; and posterior parapodia with 1–6 acicula and 1–5 capillaries per bundle. Genetic data, sequencing of the cytochrome oxidase subunit I (COI) of L. tantawan sp. nov., and R. plahmuk sp. nov., are reported. Update keys for identifying species of Fauveliopsis, Laubieriopsis and Riseriopsis are also provided.
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DNA barcoding for elasmobranch diversity assessment in Thailand: Its advantages and limitations
(2025-10-01)
Khudamrongsawat, Jenjit
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Krajangdara, Tassapon
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Panithanarak, Thadsin
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Karuwancharoen, Ratima
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Klangnurak, Wanlada
The assessment of elasmobranch biodiversity in Thailand benefits greatly from the application of DNA barcoding, which helps mitigate the challenge posed by a shortage of expert taxonomists. Fragments of COI and ND2 mitochondrial DNA were examined, and the strengths and weaknesses of these two markers were compared. In this study, DNA products from 153 elasmobranch samples were amplifiable and revealed a total of 28 shark species and 32 batoid species. Many species could be confidently identified as their morphological characteristics aligned with DNA barcodes. However, several exceptions were recognized. The absence of reference sequences for rare species presented a challenge for species verification, and the misidentification of reference sequences, as well as changes in species names due to taxonomic revisions, added complexity when comparing DNA barcoding sequences. Conflicts between morphology and genetics were also observed. While intraspecific genetic variation based on both DNA barcodes generally indicated 0–2% variation, this metric could not always be used for species delimitation. This was particularly true for species displaying low genetic variation among closely related species and species where cryptic diversity remained hidden and yet to be uncovered. In such cases, the morphological characteristics of the samples served as the primary means of species identification. Despite these challenges, DNA barcoding remains an invaluable tool for biodiversity assessment, especially in light of the shortage of skilled experts, and for identification of products made from vulnerable species. However, it is essential to exercise caution and be aware of these complexities in its application.
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Assessment of Bacterial Community and Other Microorganism Along the Lam Takhong Watercourse, Nakhon Ratchasima, Thailand
(2025-06-01)
Klangnurak, Wanlada
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Hinthong, Woranich
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Aue-umneoy, Dusit
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Yomla, Rungtawan
Lam Takhong, a vital watercourse in Nakhon Ratchasima province, Thailand, supports agricultural, recreational, and urban activities. Originating in a national park, it flows through urban areas before discharging into a dam and running off via the sluice gate. While water quality monitoring is routine, microbial community data have never been reported. This study assesses the microorganism diversity and functional genes in Lam Takhong watercourse using a shotgun sequencing metagenomics approach. Water samples were collected from the upstream, midstream, and downstream sections. The midstream area exhibited the highest abundance of fecal coliform bacteria, plankton, and benthos, suggesting elevated pollution levels. Genes related to metabolism, particularly carbohydrate and amino acid pathways, were predominant. Proteobacteria was the most abundant phylum found in the water, with Limnohabitans as the dominant planktonic bacteria. Bacteria such as Staphylococcus, Mycobacterium, Escherichia, Pseudomonas, Enterococcus, Neisseria, Streptomyces, and Salmonella were detected, along with antibiotic resistance genes, raising public health concerns. These findings emphasize the need for microbial monitoring in the Lam Takhong to determine the potential water quality bioindicator and prevent potential disease spread through the water system.
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Occurrence of microplastics in Russell’s snapper (Lutjanus russellii) and associated prey species in the Central Gulf of Thailand
(2025-02-01)
Klangnurak, Wanlada
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Prachumwong, Siriluk
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Alfonso, María Belén
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Nakano, Haruka
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Chavanich, Suchana
Microplastic (MP) contamination in fish may occur via their feeding behavior and ingestion of contaminated prey. This study investigated the presence of MPs in the predator Lutjanus russellii (Russell’s snapper) and its prey along the Chumphon coast of the Central Gulf of Thailand. Stomach contents of L. russellii were analyzed to identify its prey species. Prey species were then sampled from the same geographical area as the predator specimens for subsequent MP analysis. The dietary habits of L. russellii classify it as a generalist carnivore, consuming a diverse range of food items, including zooplankton, crustaceans, and small fish. No significant correlation was observed between MP abundance and the weight or length of the predator fish (general linear model, p > 0.05). Black and red fibers were the predominant MP types in both predator and prey, though MP sizes varied among the sampled species. In predator stomachs, the most common polymers were acrylonitrile butadiene styrene (ABS; 26.32%), polyethylene terephthalate (PET; 21.05%), and polyester (PES; 10.53%). Conversely, prey samples were dominated by PES (17.58%), PET (15.38%), and ABS (13.19%). Notably, similarities in MP characteristics (shape, color, average size, and certain polymer types) were observed between L. russellii and Portunus sp. The detection of smaller PET fibers in L. russellii compared to Portunus sp. (Mann–Whitney U-test, p ≤ 0.05) suggests the transfer of MPs to L. russellii through the ingestion of hard-shelled crustacean prey. This study underscores the importance of examining predator–prey interactions to better understand MP contamination pathways in marine ecosystems, particularly in regions like the Gulf of Thailand, where plastic pollution is prevalent. Further research is required to assess the long-term ecological implications of MP transfer within marine food chains.
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Resolving Species Identification and Distribution Patterns of Neotrygon spp. in Thai Waters: Inefficiency of Morphometric Analysis and the Power of COI Gene Barcoding and Phylogenetics
(2025-01-01)
Panithanarak, Thadsin
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Karuwanjaroen, Ratima
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Utama, Chanapa
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Laongmanee, Penchan
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Meejan, Titirat
Three species of maskrays in the genus Neotrygon have previously been reported in Thai waters. However, the high morphological similarity among species within the blue-spotted maskray complex (Neotrygon spp.) makes accurate identification challenging. This study aimed to confirm species identification in Neotrygon spp. using morphometric and genetic data and to further examine their phylogenetic relationships in Thai waters by analyzing mitochondrial COI (cytochrome c oxidase subunit I) sequences. Multivariate analysis (PCA) of 37 morphometric characters from 55 specimens proved insufficient for species-level discrimination. However, molecular phylogenetic analysis of 14 unique COI sequences from Thai waters, combined with 61 reference sequences from previously documented related species and closely related species, identified two monophyletic clades. These clades corresponded to two species: N. varidens, found exclusively in the Gulf of Thailand, and N. malaccensis, recorded for the first time in Thailand, occurring in both the Gulf of Thailand and the Andaman Sea. This DNA-based identification provides clear evidence for species boundaries within Thai Neotrygon species and highlights the importance of molecular tools for distinguishing morphologically similar marine species in the Indo-Pacific region.
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Two new species of Sigambra (Annelida, Pilargidae) from the Andaman coast and the Gulf of Thailand
(2024-12-17)
Plathong, Jintana
;
Plathong, Sakanan
;
Klangnurak, Wanlada
;
Dean, Harlan K.
Two species of Pilargidae, Sigambra pakbaraensis sp. nov. and S. sirilukae sp. nov. are described from different coasts of Southern Thailand (Andaman Sea and the Gulf of Thailand). Both species belong to the subgroup of Sigambra which lack ventral cirri at chaetiger 2 and have capillary notochaetae. Sigambra pakbaraensis sp. nov. is described from the Andaman coast and can be distinguished from other species in the genus by the occurrence of the first dorsal hook at chaetiger 8, the presence of capillaries in notopodia, and 14 pharyngeal papillae. Sigambra sirilukae sp. nov. is described from the Gulf of Thailand and it is clearly distinguished from all other species in the genus by having 12 pharynx papillae, an elongate median antenna with a large ceratophore, dorsal hooks from middle chaetigers, and up to five capillary notochaetae from anterior most chaetigers (4–5). Molecular phylogenetic analyses, based on cytochrome oxidase subunit I (COI) and mitochondrial genes 16S, indicate S. pakbaraensis sp. nov. clusters within Sigambra Müller, 1858. Pores on the dorsal and ventral cirri of both species are herein described for the first time for the genus. An updated key to species of Sigambra from the Indo-Pacific region is also provided.

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