A comparative study on eDNA-based detection of Siamese bat catfish (Oreoglanis siamensis) in wet and dry conditions.

The use of environmental DNA (eDNA) analysis has demonstrated notable efficacy in detecting the existence of freshwater species, including those that are endangered or uncommon. This application holds significant potential for enhancing environmental monitoring and management efforts. However, the efficacy of eDNA-based detection relies on several factors. In this study, we assessed the impact of rainfall on the detection of eDNA for the Siamese bat catfish (Oreoglanis siamensis). Quantitative polymerase chain reaction (qPCR) analysis indicated that samples from days with average rainfall exceeding 35 mm (classified as heavy and very heavy rain) yielded negative results. While eDNA detection remains feasible on light or moderate rainy days, a noteworthy reduction in eDNA concentration and qPCR-positive likelihood was observed. Analysis across 12 sampling sites established a statistically significant negative relationship (p < 0.001) between eDNA detection and rainfall. Specifically, for each 1 mm increase in rainfall, there was an observed drop in eDNA concentration of 0.19 copies/mL (±0.14). The findings of this study provide definitive evidence that precipitation has a significant impact on the detection of eDNA in Siamese bat catfish. However, in the case of adverse weather conditions occurring on the day of sampling, our research indicates that it is acceptable to continue with the task, as long as the rainfall is not heavy or very heavy. To enhance the effectiveness of an eDNA survey, it is crucial to consider many factors related to climatic conditions. The aforementioned factor holds significant importance not only for the specific species under scrutiny but also for the broader dynamics of the climate.

An eDNA-based assessment of Garra cambodgiensis (stonelapping minnow) distribution on a megadiverse river, the Mekong.

Garra cambodgiensis (stonelapping minnow) has experienced significant population declines, prompting intensive research and management, although its distribution in river systems such as the Mekong remains obscure. Effective conservation and management necessitate accurate monitoring and survey data on the distribution of freshwater species. Traditional surveying techniques for fish may be challenging and generate insufficient data on species distribution. This study developed an eDNA-based method for detecting G. cambodgiensis to address this void. Twenty-one locations were surveyed. Water samples were collected in triplicate from the river's surface at each site and processed within 48 h in a dedicated laboratory. Primers and probes for G. cambodgiensis were meticulously designed and species-specificity tested to ensure accurate detection without interference from co-occurring species in the same geographic range. Each water sample was analysed by qPCR using six technical replicates. The results of qPCR were reported as positive with quantifiable eDNA concentration (copies/mL), below the limit of quantification, or non-detectable. G. cambodgiensis eDNA was detected in water samples collected from 10 out of 21 sampling sites, with concentrations ranging from 8.5 to 2990.0 copies/mL. Importantly, G. cambodgiensis eDNA was consistently detected in all three replicate water samples at each site where the qPCR experiment yielded positive results. The findings of this study demonstrate the feasibility and effectiveness of incorporating eDNA-based monitoring or surveys for G. cambodgiensis in the ecologically diverse Mekong River. Monitoring based on eDNA can aid in targeting and informing conservation and management of G. cambodgiensis in its natural habitat. Comprehensive and robust information on species distribution can be obtained via an eDNA-based survey, which could contribute to more efficient and informed decision-making processes in fisheries management and conservation efforts.

Revision of the genus Ultragryllacris (Orthoptera: Stenopelmatidae: Gryllacridinae), with description of new species.

The genus Ultragryllacris was revised. All its species and subspecies, including U. jiaranaisakuli sp. nov., U. chandra sp. nov. from Western Thailand and U. intermediata sp. nov. from Northern Thailand are here described and redescribed. They are known from Thailand and China. The new species differs from all the other representatives of this genus mainly in different body coloration, shape of projection of male 9th abdominal tergite and sclerotized area of female subgenital plate. The following taxonomical changes are also proposed: U. pulchra alboclypeata Gorochov et Dawwrueng, 2015, U. p. nan Ingrisch, 2018 and U. p. rubricapitis Bin et Bian, 2021 are raised to species status (U. alboclypeata stat. nov., U. nan stat. nov. and U. rubricapitis stat. nov.) due to some characteristic structures in both male and female; U. triangula Ingrisch, 2018 is downgraded to subspecies of U. alboclypeata (U. a. triangula stat. nov.). Previously unknown male of U. a. alboclypeata and female of U. nan are described. A key to all known species is given.

A new species of Cyrtodactylus Gray, 1827 (Squamata: Gekkonidae) from the Thai-Malay Peninsula and the independent evolution of cave ecomorphology on opposite sides of the Gulf of Thailand.

An integrative taxonomic analysis recovers a distinctive new species of the gekkonid genus Cyrtodactylus Gray, 1827 from Satun Province in extreme southern Thailand as the sister species to the Cyrtodactylus intermedius group of southern Indochina, approximately 600 km to the northeast across the Gulf of Thailand. Based on 1449 base pairs of the mitochondrial gene NADH dehydrogenase subunit 2 (ND2) and its flanking tRNAs, the new species, C. disjunctus sp. nov., bears a pairwise sequence divergence from the mean divergences of the intermedius group species ranging from 17.923.6%. Three different principal component analyses (PCA) and a multiple factor analysis (MFA) recover C. disjunctus sp. nov. as a highly distinctive karst cave-adapted species based on morphology and color pattern. Its sister species relationship to the intermedius groupto which it is added herefurther underscores a growing body of analyses that have recovered a trans-Gulf of Thailand connection across the submerged Sunda Shelf between the southern Thai-Malay Peninsula and southern Indochina. Fragmented karstic archipelagos stretching across Indochina have served as foci for the independent evolution of nearly 25% of the species of Cyrtodactylus. The description of C. disjunctus sp. nov. continues to highlight the fact that karstic habitats support an ever-increasing number of threatened site-specific endemics that compose much of the reptile diversity of many Asian nations but, as of yet, most of these landscapes have no legal protection.