Acta Zoologica最新文献

This study investigated the morphological variation of gibel carp Carassius gibelio collected from various water bodies in Türkiye. The fish samples were obtained from three dams (Karacaören-1, Karakaya, and Keban), two natural lakes (Beyşehir and Suğla), and a river (the Tigris River). The dimorphism in body shape was examined with geometric morphometrics, while elliptic Fourier analysis and shape indices were used to describe the variation in lapilli otoliths (hereafter “otoliths”) and scale shapes. The body of C. gibelio revealed higher variations, particularly in the body depth, snout length, caudal fin, and caudal peduncle, among different stations. Geometric morphometric analysis determined a streamlined body shape of C. gibelio in the Tigris River compared to other stations, while C. gibelio from the natural lakes had a deeper body shape. The body of C. gibelio exhibited a significant homogenous shape between the Beyşehir and Suğla lakes, providing the lowest Procrustes distance. The elliptic Fourier analysis revealed that the otolith shape varied significantly between all stations. However, the scale shape was remarkably similar among nearby areas such as Karacaören dam, Suğla, and Beyşehir lakes. These results evinced high degree of intra-population morphological variation in C. gibelio in response to prevailing environmental conditions that probably facilitate their successful establishment in a novel environment.

This study describes important components of the reproductive biology of the Amazonian amphibian fish Copella arnoldi. The species sex ratio biased to female 1.8 to 1 male and the length-weight relationship also shown differences between sexes (b value = 1.854 for females and 2.235 for males), although both presented allometric growth (b < 3), “being lighter for its length”. The results also show the importance of the histological analysis to describe the gametogenesis and, consequently, define the reproductive cycle of a fish species. It showed both, males and females, spawning capable during a whole year, whereas the gonadosomatic index pointed spawning capable females during the winter and summer, and spawning capable males only in the autumn. The species presents the rare type of semicystic spermatogenesis and the spermatids complete their differentiation into the tubular lumen, forming a Type I spermatozoa. Both the characteristics are described for the first time for the Lebiasinidae family. Such data can contribute to the discussions about the position of the Lebiasinidae family within the Characiform order, which still does not have a conclusion. Moreover, understand the reproductive biology of a fish species helps its preservation in its habitat and may be applied in restoration programs.

There is a significant gap in our knowledge of the intraspecific morphological variability in freshwater fish, although such data are crucial for understanding species diversity. Here we use the killifish Aphaniops stoliczkanus (Day, 1872; Aphaniidae: Cyprinodontiformes), which is a widespread but poorly known freshwater species in the Middle East, to investigate variability in morphological traits within and between its populations. As otolith morphology is known to evolve on ecological timescales and can signal the presence of cryptic lineages, a special focus lies on otolith variability. Based on samples from six populations in northern Oman, we found that variation in pigmentation, disparities in body shape and otolith variability can be associated with distinctive environmental conditions. The unique otolith shape of A. stoliczkanus from a hot sulphuric spring (Nakhal) suggests that a cryptic lineage may have emerged there. Our new data can serve as a benchmark for future studies on the diversity of Aphaniops and other Aphaniidae and help to clarify whether cryptic diversity is present in some lineages. Moreover, our data can serve as an actualistic model for studies on fossil fishes, in which morphological characters provide the only accessible data source for taxonomic and phylogenetic interpretations.

Capnodis tenebrionis causes damage in many species of Rosaceae. The present study investigates on the morphology of the female reproductive system of C. tenebrionis. The female reproductive system of C. tenebrionis has a pair of ovaries, lateral oviducts, a common oviduct, spermatheca, and bursa copulatrix. Each ovary in C. tenebrionis consists of approximately 24 telotrophic meroistic type ovarioles. The ovarioles of C. tenebrionis have four regions (terminal filament, tropharium, vitellarium, and pedicel). Tropharium have trophocytes, young oocytes, and prefollicular cells. Vitellarium consists of previtellogenic, vitellogenic, and choriogenic oocytes. Previtellogenic oocyte is surrounded by cylindrical epithelial cells. Its ooplasm is homogeneous and basophilic. In vitellogenic oocyte, there are intercellular spaces between monolayered follicle cells. Its ooplasm has yolk granules and lipid droplets. Choriogenic oocyte are surrounded by chorion and single-layered cylindrical cells. There are yolk granules and lipid droplets in its ooplasm which is asidophilic. In C. tenebrionis female, spermatheca and bursa copulatrix wall is surrounded by thin cuticular intima, monolayer epithelial, glandular cells, and muscle layer. Spermatheca lumen contains a large number of spermatozoa. Bursa copulatrix lumen is filled with secretory material. This study may be useful in terms of the morphology of mature female reproductive organs of Buprestidae and other coleopteran species.

Under temperature sex determination (TSD), sex is determined by temperature during embryonic development. Depending on ecological and physiological traits and plasticity, TSD species may face demographic collapse due to climate change. In this context, asymmetry in bilateral organisms can be used as a proxy for developmental instability and, therefore, deviations from optimal incubation conditions. Using Tarentola mauritanica gecko as a model, this study aimed first to confirm TSD, its pattern and pivotal temperature, and second to assess the local adaptation of TSD and variation of asymmetry patterns across four populations under different thermal regimes. Eggs were incubated at different temperatures, and hatchlings were sexed and measured. The number of lamellae was counted in adults and hatchlings. Results were compatible with a TSD pattern with males generated at low and females at high incubation temperatures. Estimated pivotal temperature coincided with the temperature producing lower embryonic mortality, evidencing selection towards balanced sex ratios. The temperature of oviposition was conservatively selected by gravid females. Asymmetry patterns found were likely related to nest temperature fluctuations. Overall, the rigidity of TSD may compromise reproductive success, and demographic stability in this species in case thermal nest choice becomes constrained by climate change.

The objective of the study was to histologically describe the structure of the testis and epididymis, identifying the GAGs in them. Furthermore, the distribution of smooth muscle alpha-actin, desmin, and vimentin is described of E. bilineatus, E. perditus, and U. vautieri, through immunohistochemical method. Two adult males of each species of the lizards were collected in southeastern Brazil. In the testicular albuginea, the presence of neutral glycoproteins was detected. In E. bilineatus, the epididymal duct epithelium is simple, composed of secretory cells, cylindrical in shape and acidophilic cytoplasm. In the testis of the three lizards there was a positive immunolocation accentuated for α-SMA in the dense connective tissue of the tunica albuginea. A moderate reaction was observed in the connective tissue albuginous and in the layer of smooth muscle fibers in a circumferential arrangement of the epididymal duct. The immunolocation for desmin was accentuated in the fibers of the testicular albuginea of E. bilineatus, while in U. vautier and E. perditus was moderate. In the epididymis, only in E. perditus and E. bilineatus positive immunoreaction was verified. In the three lizards there were no observations of immunostaining for vimentin with the antibody utilized.

Canarium (Canarium) incisum and Canarium (Canarium) esculentum are small members of the molluscan Strombidae family. Little is known of their population structure. Therefore, we explored this using samples from a population of each. The first sample from Corong Corong Beach, El Nido, Philippines, consisted of 81 adult C. incisum, of which 33 were female and 48 were male. The second sample from Olango Island, Philippines consisted of 73 adult C. esculentum, of which 40 were female and 33 were male. Bias in sex ratio between species was not significant. However, there was bias in sex ratio within species, where males from both species were smaller in axial length than females. We found no evidence of pseudohermaphroditism. The black colouration of the aperture is a phenotype shared by many stromboidians, and 7.4% of C. incisum population exhibited this trait, while the C. esculentum population contained 50.1% black apertures specimens. Preliminary DArTseq analysis indicates that organisms with the black aperture colouration are nested within the populations. Our study fills a knowledge gap on C. incisum and C. esculentum population structure, and gives greater insights to size dynamics of stromboidian taxa in general.

Sesarmid crab, Muradium tetragonum, considered a key detritus consumer plays a significant role in the nutrient cycling and energy flow in most of the mangrove environments. Morphological and ultrastructural organization of the M. tetragonum male reproductive system are characterized through transmission electron microscopic studies. Adult males (3.2–4.2 cm) with dark violet carapace and white-tipped cheliped were procured alongside the coastal areas of Tanjavur district, Tamil Nadu, India. The morphological analysis highlights the male gonads to be bilaterally symmetrical and anterolaterally located inside the cephalothorax. A pair of elongated testes lying attached to the hypodermis of the carapace leads to a long highly coiled vas deferens categorized into three distinct regions (Proximal vas deferens, Middle vas deferens and distal vas deferens) structurally and functionally with Posterior vas deferens receiving sac-like accessory glands. It gets followed by an ejaculatory duct and ends with the penile papillae at the coxae's base of the fifth peripod. Structural modifications were observed in the ultrastructure of vas deferens envisage (considering) its functional role in storing spermatophores, active absorption and assisting the secretory activity. Spermatophores, witnessed as spherical bodies are bounded by a dense double wall. Aflagellate, immotile and spherical spermatozoa that measuring 3.6 μm in diameter encompasses a complex acrosome cupped by a nucleus. Moreover, perforatorium and the extending nuclear arms with chromatin, as displayed in the experimental organism M. tetragonum, are in synergy with that of certain brachyurans as specified in the study. Hence, the current study assessing the morphology and ultrastructure parameters of the male gonads could be useful in understanding the physiology of sexual maturation, annual cyclic changes, tracing the phylogenetic relationship among species and enhancing the brood-stock management.

Developmental programmes for many marine invertebrates include the assembly of muscular systems appropriate to the functions of swimming and feeding in pelagic larvae. Upon metamorphosis, that musculature is often radically re-organized to meet very different demands of post-larval life. To investigate the development and fate of musculature in the nudibranch Phestilla sibogae, embryos, larvae and metamorphosing stages were fixed, labelled with phalloidin and examined with confocal microscopy. The resultant images revealed the sequential development of both large retractor muscles and numerous finer muscles that allow the larva to manipulate the velum, foot and operculum. Observations of living specimens at the same stages as those fixed for microscopy revealed the actions of the muscles as they developed. During metamorphosis, muscles with shell attachments disintegrate as the larva transforms into a shell-less juvenile. Notably, the massive velar, pedal and opercular retractor muscles disappear during metamorphosis in a sequence that corresponds to their loss of function. Other muscles, however, that appear to be important to the embryo and free-swimming larva persist into juvenile life. The comprehensive and detailed observations of the musculature presented here provide a solid foundation for comparisons with other species with different phylogenies and life histories.

Scale and otolith morphology and morphometry of Indian oil sardine Sardinella longiceps (Clupeidae) were investigated and described using light and scanning electron microscopy from eight different body regions for scales and the right and left otoliths. Scales of the Indian oil sardine show general characteristics of the other studied clupeids sand that are easily distinguishable from other fish groups, by having striae in the posterior field. The studied cycloid scales of S. longiceps were classified into three types based on the overall shape including circular (e.g. true circular and cordate), pentagonal and quadrilateral in the different body regions. The circular shape was the most common shape (87.5%), while the quadrilateral and pentagonal forms constituted 6.25% each. The results also showed that the relative scale size (J-index) plays a desirable contribution in separating the examined populations. The results showed that the mean (or relative) scale size for all the eight regions in the Oman Sea population is larger than the Arabian Sea population. Also, another scale variable, the scale shape index (Si index), demonstrated variation (a mean of 0.86 to 1.1) in different regions of both populations from the Oman and Arabian Seas. Interestingly, here, we found that scale characters of S. longiceps not only differ from its other congeneric species, but also differ in the populations from both sides of the Oman Sea (Iran and Oman) and the Arabian Sea. It shows a positive signal for the presence of different taxonomic and management unit in the Oman and Arabian Seas. The idea should be approved by using integrated molecular and morphological traits. The otolith morphology of S. longiceps from the Oman and Arabian Seas was more conservative than the scales, which can be due to its function actin primarily as a balance organ and also enhancing hearing. The overall shape of S. longiceps otolith was lanceolate, with an elongated morphology and a well-developed rostrum, an ostial sulcus acusticus that opens to the anterior/ dorsal margin. These morphological characters are also found in the Iranian population of S. longiceps. However, otolith displayed variation in biometric parameters among two populations and left and right otoliths and the RRL parameter were important characters to discriminate the Oman and Arabian Sea populations. Thus, the structural/biometrical variability of the otoliths may be used for population distinctness, especially in water bodies with various environmental factors, and the otolith has turned out to be a useful tool to track the life history of teleostean fishes in environments with physicochemical gradients.