Acta Zoologica最新文献

Honey bee hive infestation by the ectoparasitic mite, Varroa destructor, has been a major cause of declining populations. Treating such infestations is important for sustainability. Knowledge about the sub-lethal effects of commonly used acaricides on drone reproductive health, particularly sperm quality, is limited. The effect of in vitro and in vivo acaricide (amitraz) exposure was evaluated using Cape honey bee (Apis mellifera capensis) drone body size and sperm quality. For the in vitro study, semen samples were exposed to three concentrations of amitraz (125, 250, 500 μM). The in vivo study entailed in-hive Apivar treatment as per commercial recommendations. Adult drones were harvested following three weeks of treatment. Drone body weight (determined in the in vivo study only) was significantly higher in amitraz-exposed drones. No correlations were found between drone weight, sperm volume or concentration. In both studies, amitraz exposure had statistically insignificant effects on sperm motility and structure, while vitality significantly decreased in the 500 μM amitraz-exposed in vitro group. Sperm structure remained unaffected in both studies. This study highlighted the absence of sub-lethal effects of high doses of amitraz on sperm functionality. When used as advised, amitraz exposure does not have a detrimental effect on drone sperm quality.

Parreira. I.P. 2025. Age structure and size variation in three closely related species of casque-headed frogs of the genus Trachycephalus (Hylidae: Lophyohylini)—Acta zoologica (Estocolmo). This study provides insights into longevity, sexual maturity and growth curves in closely related casque-headed treefrogs distributed across distinct Brazilian biomes. Age estimation based on the counting of lines of arrested growth (LAGs) in bone tissue revealed a longevity of 6 years in Trachycephalus nigromaculatus and T. atlas, which is uncommon among Neotropical species. T. mambaiensis exhibited a distinct pattern of sexual maturity compared to the other species, suggesting divergent developmental strategies within the clade and possibly reflecting a higher reproductive investment at younger ages. A correlation between estimated age and snout–vent length (SVL) was observed in two of the three analysed species (T. nigromaculatus and T. atlas); however, this correlation may vary depending on the sampled locality and sample size. The growth model revealed distinct patterns within the clade: T. nigromaculatus exhibited a decline in growth rate corresponding to the age of sexual maturity, whereas T. atlas showed a non-stabilised growth pattern. Our findings provide novel information for understanding the life history of explosive breeding species and emphasise the importance of museum specimens in ecological and evolutionary research.

The Micro-computed X-ray tomography (micro-CT) technique is used to examine the external and internal anatomy of four species of Pectinariidae (Annelida: Terebellida): Amphictene auricoma, Cistenides granulata, Cistenides hyperborea and Lagis sp., from material collected off Iceland and NW Spain. The main aims were: (1) to provide new and additional observations on pectinariid external and internal anatomy, (2) to test the usefulness and limitations of micro-CT against other techniques and 3) to explore for characters with potential taxonomic value to be studied in the future. Micro-CT provided good images of several external relevant taxonomic characters such as paleae, cephalic veil, scaphe, scaphal hooks and anal lobe, but was especially useful for the examination of internal anatomy. The best visualized organs were those of higher tissue density (i.e. body musculature, digestive tract, main blood vessel, glands), whereas less electrodense tissues (i.e. peritoneal lining/septa, nephridia, nervous system) were less evident. Images of internal organs showed heterogeneous results: micro-CT may serve well to assess regionalization of digestive system and its variability across taxa, together with musculature and glands, while images of circulatory and nervous systems only show good results in their more electrodense components (main blood vessels/heart and ventral nerve cord/brain, respectively).

Excessive metal pollution from anthropogenic activities like mining and industrial waste discharge has increasingly impacted freshwater ecosystems. Freshwater chelonians (Testudines) are bioindicators of environmental pollution because of their longevity, ecological diversity, and trophic positioning. This systematic review assessed toxic metal bioaccumulation in freshwater turtles across the American continent, focusing on mercury (Hg), a global public health and ecological concern. A comprehensive search on PubMed, Scopus and Web of Science identified 620 papers, of which 32 met the inclusion criteria. The United States and Brazil (93.6%) contributed the most data, with Chelydra serpentina and Podocnemis expansa frequently studied, followed by Canada (4.26%) and Colombia (2.13%). Hg was the predominant contaminant (75% of studies), with the highest concentrations observed in hatchlings and keratinized tissues, such as carapace and claws. Bioaccumulation patterns varied by region, species and life stage, emphasizing physiological and reproductive impacts. This review highlights the need for noninvasive sampling methods and long-term monitoring to guide conservation strategies and assess ecosystem and turtle health. It also highlights the significant lack of data in South America and the lack of studies on juveniles and eggs. Freshwater chelonians remain essential for understanding contamination dynamics and mitigating environmental degradation in aquatic habitats.

This study examines eight skeletal features to distinguish species within the Cobitidae and Nemacheilidae families, focusing on the vertebral column, fin structure and caudal fin rays. The study analyses the construction and regionalization of the vertebral column, the interdigitation of pterygiophores with neural and haemal spines in the dorsal and anal fins, and the distribution of procurrent rays in the caudal fin. These characteristics are used to identify taxonomically relevant traits and separate species within these two families. The study also proposes a new method for defining vertebral column regions and presents new anatomical data for cobitoid species in Iran, including the division of the vertebral column into five regions: postcranial, abdominal (anterior and posterior) and caudal (anterior and posterior).

The relationship between the total length of fish and the morphometric characteristics of their otoliths (length, width, and weight) was examined in striped snakehead (Channa striata, Bloch, 1793) specimens collected from the River Ganga and its two tributaries in India. Channa striata, a commercially valuable species in India, was the focus of this study, which aimed to analyse the statistical correlations between the fish's total and standard lengths and their corresponding otolith measurements, with the expectation that the data will contribute to future research on the species' biology, particularly its age, and growth patterns. Both linear and non-linear regression models were applied, and the regression equations varied significantly between the three collection sites. These findings represent the first investigation into the relationship between otolith morphology and total fish length for striped snakehead from the River Ganga and its tributaries in India.

The following subject provides an in-depth look into the significance of rodents in the Souf region concerning agriculture and ecology. The article points out that rodents, as mammals, play a critical role in various ecosystems, with many mammalian species being rodents. They contribute to agriculture, sanitation, food, medicine, ecology and religion. Rodents play a vital role in vegetation dynamics by spreading plant seeds and influencing predator distribution. However, preying on crops can also cause losses in different ways, depending on the plant type and biotope. The study focuses on eight research stations in the Souf region, describing their characteristics and vegetation. The methods used for rodent inventory include fingerprinting, burrow counting and random trapping using different techniques. Statistical methods are then applied to analyse the collected data. The study identifies ten rodent species in the Souf region, belonging to two families, three subfamilies and five genera. The sex distribution varies among species. The study results reveal variations in rodent abundance across different stations and months, with Rattus rattus and Mus musculus being the most common species in certain stations. The diversity and equitability values indicate a relatively balanced distribution among recorded species in the sample period. The study provides comprehensive insights into rodent ecology, behaviour and distribution in the Souf region, emphasizing their importance and potential impacts on agriculture and ecosystems.

The first record of the abnormalities ankylosis (fusion of vertebrae), lordosis (V-shaped curvature of the vertebral column), kyphosis (Λ-shaped curvature), and kypholordosis (the presence of both conditions) have been reported in two specimens of Sparus aurata collected from Bafa Lake and Bodrum-Kıyıkışlacık Coast, Türkiye and used in this study. Both specimens displayed a severe level of deformity. All cases were non-fatal as they occurred in subadult individuals. Assessment of abnormality in the studied specimen was carried out by the morphological diagnosis and using mammography. Externally, the two specimens have a deeper body than the normal specimen. There was significant osteological damage has been revealed by the mammography of these deformed specimens. The saddleback anomaly is in the anterior part of the spinous part of the dorsal fin that showed no missing spines. In addition, the lateral line was deformed in both specimens examined. In addition, there were several minor skeletal abnormalities. These anomalies have been considered an important indicator of environmentally induced stress on the wild fishes. Hence, the present finding highlights the need for closer monitoring of the marine environment and for the identification of the specific factor that causes these abnormalities.

This study aimed to identify unique traits, grounded in a thorough description of the sagitta otolith of Anguilla anguilla, to characterize its ontogenetic stages between juvenile and preadult individuals. Twenty-one characteristics were designated to investigate the ontogenetic (when comparing the otolith characteristics of fishes of different sizes, interspecific variation (comparing the otolith characteristics of the studied species with those of related species), and intraspecific variation (comparing the otolith characteristics of the studied species with those of the same species from different localities, i.e. geographical variation). This investigation concluded that the sagittal otoliths exhibited ontogenetic disparities based on the shapes recorded by different age groups. Otoliths of the young individuals belonging to fish total length groups GI and GII have shown differences in shape from those of the older individuals in the other seven length groups surveyed. An assessment of previously available otolith descriptions of A. anguilla collected from other areas revealed differences between species across larger geographic areas, making some features unsuitable for further investigation. However, other otolith traits were found to be reliable across different length groups and could be considered species-specific features for identification. These traits include otolith width, otolith thickness, the shape of the mesial and lateral surfaces, the shape of the sulcus acusticus, the presence or absence of ostio-caudal differentiation, and the shape, size, and thickness of the rostrum.

Jeamah, A., Sudtongkong, C., Kenthao, A., Imsonpang, S., Angsujinda, K., Charoenphon, N., Inchan, A., Kongtueng, P., Mitparian, M. & Senarat, S. (2023). Acta Zoologica. 2023;104(4):575–585.

In “Materials and Methods” section, the text “were collected in June 2020” was incorrect. This should be corrected to: “were collected in June 2021.”

We apologize for this error.