Zoomorphology最新文献

In 2021/2022, galls formed by a nematode, Anguina woodi, were found on the stems, leaves and leaf sheaths of dune grass, Ehrharta villosa var. villosa on Milnerton Beach, Blouberg Beach and Langebaan, Western Cape Province, South Africa. These galls were spongy in texture, deep purple to blackish in colour and non-pedunculate. They were found in clusters, but also as single entities. Larger, harder galls varying from beige to dark brown in colour, apparently caused by insects, were also found on the stems of dune grass at Blouberg Beach and Langebaan Nature Reserve. Some nematode galls were found immediately next to or on top of the insect galls. Those found on top of insect galls seemed to be harder and drier than those found on stems not infected by insect galls. The co-infection of insects and anguinid nematodes has not been reported from the current study areas and was thus included in the present study. Both molecular and morphological studies were conducted on the nematodes and wasps leading to the identification of a host specific, gall-forming nematode from all three localities. The wasps were identified morphologically and molecularly to the family Eurytomidae (Hymenoptera). No insect galls were found on dune grass from Milnerton Beach. The paper includes speculations on a probable association between nematodes and insects.

Abstract

Several studies have documented the occurrence of hyperostosis, a bone condition that results in bone thickening, in specimens of Trichiurus lepturus, an important commercial species. A total of 102 Largehead Hairtail fish samples from Rio de Janeiro, Brazil, were obtained from artisanal fishers and divided into 4 size classes. Biometric measurements and radiographic images were taken for all exemplars. Hyperostosis was observed in 69.69% of the individuals, with the first detection of the condition in an exemplar measuring from 385 mm in total length. The affected skeletal regions included the cleithrum, supraoccipital, frontal, dorsal pterygiophores, and haemal spines. An increase in the occurrence frequency of hyperostosis was noticed in correlation with size, suggesting a connection with the aging process and an ontogenetic pattern for the species. Histological analysis indicated a high remodeling process in affected structures. In addition, we highlight the specie daily vertical migration, associated with temperature variation, as a potential contributor to the onset of this osteological condition in marine teleosts.

Crassostrea gasar is a bivalve mollusk of economic interest in the Amazon estuary, because it displays good zootechnical performance and nutritional value. However, there is still a gap in the literature regarding studies on basic biology, especially spermatogenesis at the ultrastructural level. This study aimed to describe for the first time the male gonad development. Gonad fragments were analyzed using light microscopy and transmission and scanning electron microscopy. The ultrastructural analysis of the gonadal tubule showed two distinct cell populations: support cells and the cells of the spermatogenic lineage. Regarding the ultrastructural aspects, support cells were characterized by an irregular shape, sparse electron-dense cytoplasm, and a large nucleus with condensed chromatin; and two types of spermatogonia were seen (A and B); spermatocytes I where it was possible to characterize four stages of prophase I, namely leptotene, zygotene, pachytene, diplotene; spermatocytes II showing a reduction in cytoplasmic and condensed chromatin. Spermatids were classified into three stages of development: early, middle, and late. Mature spermatozoa are of the primitive type and have a cone-shaped head with a discoidal acrosome, a midpiece formed by four mitochondria, and a long flagellum. This information can help establish phylogenetic relationships between species of the genus Crassostrea. In addition, these findings can support conservation biology by developing and implementing biotechnological approaches, such as cryopreservation, and contributing to commercial-scale cultivation in the Amazon region.

Graphical Abstract

Otophysi is one of the most important fish taxa of the world, as they make up for roughly 28% of all fish species and about two-thirds of all freshwater species worldwide. To understand their success and evolutionary history their sister-group, the Gonorynchiformes, take a key-position, e.g., for reconstructing morphological conditions in the latest common ancestors. Gonorynchiformes comprising only 40 species and have been often studied for that reason. Their pelvic girdle, however, got only little attention so far. Therefore, we studied this structure in extant gonorynchiforms and described the ontogeny in Kneria stappersii. In gonorynchiforms: (1) their basipterygium is principally flat (without dorsal or ventral projections) and placed in horizontal position, (2) has a ‘simple’ shape, i.e., it has only a single anterior process with small cartilaginous tips and becomes wider in its posterior part with a medial portion connecting to the basipterygium of the other side; (3) three radials and a pelvic splint are present, and (4) a prominent posterior process is missing. Although, the morphological situation is a lot similar as seen in clupeiforms and alepocephaliforms. Therefore, these characters have likely been present in the stem of Otomorpha, Ostariophysi, and Otophysi, but within the latter taxon eventually, a higher diversity of pelvic girdle morphology arose during evolution.

Geranoaetus melanoleucus is a widely distributed accipitrid across South America. Like other accipitrids, it employs powerful hindlimb muscles to capture and immobilize prey. Whereas previous research has focused predominantly on the grip muscles of diurnal raptorial birds, detailed myological descriptions of the entire hindlimb are lacking. This study offers a comprehensive overview of the hindlimb musculature of G. melanoleucus, comparing it with existing information on other raptors. Several features are shared with other accipitrids, including the absence of m. flexor cruris lateralis, the fusion of m. iliotrochantericus cranialis and medialis, and a vinculum connecting distally m. flexor hallucis longus and m. flexor digitorum longus, among others. However, G. melanoleucus exhibits distinctive characteristics, such as a smaller origin area for m. tibialis cranialis and a distal trifurcated tendon of m. flexor perforatus digiti IV, among others. Similar to other diurnal raptorial birds, digit flexors constitute the majority of the muscle mass, aligning with their primary role in grip force generation. In summary, accipitrids appear to demonstrate a conservative muscular anatomy pattern, but the study of different species is crucial for detecting specific features and taxonomic differences. Moreover, detailed myological descriptions provide essential information for morphofunctional analyses.

The current study aims to differentiate, morphologically, between the masticatory muscles in black-tip sharks and shovelnose ray fish, which control the opening and closure of jaws. This work was applied to four specimens of each species, obtained from the Red Sea in Suez. Anatomical dissection was conducted on the cephalic region is order to expose the musculature. The obtained results illustrate each muscle's position, origin, and insertion. The common muscles involved in the feeding of both species were the muscles of mandibular arch: adductor mandibulae, levator palatoquadrati, while the muscles of hyoid arch were levator hyomandibulae, also the hypobranchial arch contained coracomandibularis, coracohyoideus, and coracoarcualis. All muscles of the jaws are responsible for the abduction of mouth except Adductor mandibulae M, Intermandibularis M. involved in closing the mouth, in addition, Preorbitalis M. assists in protruding of upper jaw.

Morphological and reproductive characteristics of brine shrimp Artemia from two western Algerian populations (El Melah and Timimoun) were studied for the first time alongside the northwestern population (Bethioua). Sexual, survival, growth, and reproduction were recorded for each population raised under standardized culture conditions. The morphological results showed that Artemia from the Timimoun and El Melah populations are bisexual, while the Bethioua population is parthenogenetic. After 20 days at salinity of 80 PSU, higher survival rates were found for the El Melah (85.5%) and Timimoun (72.0%) populations, while the Bethouia population showed the lowest survival rate (30.2%). Total body lengths of naupliar stages of the parthenogenetic populations were significantly longer than those of the bisexual populations. The Bethouia population displayed the highest absolute growth rate resulting in the largest adults compared to the bisexual populations. El Melah and Timimoun females were significantly larger morphologically in seven of the nine morphological characteristics compared to their respective males. The Bethouia females had smaller total and abdominal lengths compared to the females from the bisexual populations. The bisexual strains were significantly different from the parthenogenetic population in 9 of the 11 reproductive characteristics. Bethouia females, however, had the highest offspring/day/female and longest post-reproductive period compared to bisexual females. The Timimoun population adapted reproductive strategies differently compared to the other two populations: a late maturity (21.6 days), and more offspring/females (65.1). The data from the study will help future management and potential development of the Algerian brine shrimp populations.

This communication deals with seasonal variation of protozoans of edible ornamental fishes of West Bengal, India. During this survey, 1566 edible ornamental fishes were collected from different fish farms, ponds, and nearby markets of several district of West Bengal namely, Nadia, South 24 Parganas, Hooghly, North 24 Parganas, Birbhum, Purba Barddhaman, and Paschim Barddhaman from November 2019 to December 2022. Three ciliate ectoparasites belonging to the genera Trichodina, Trichodinella, and Tripartiella and three myxozoan parasites belonging to the genera Myxobolus, Thelohanellus, and Kudoa have been identified from edible ornamental fish, namely, Anabas testudineus, Bloch, 1792. Our study shows ciliate parasites have a higher rate of infection than myxozoan parasites. The highest prevalence of ectoparasitic infection has been reported during the post-monsoon season, i.e., from November to February, followed by monsoon season while lowest prevalence has been observed during pre-monsoon season, i.e., March to June, implying that environmental variables play a role in the spread of infections. The identification of these ciliates and myxozoans parasites was done by a widely used staining technique, along with an ultrastructural study of the myxozoan parasites using scanning electron microscopy. The current work also reveals the histopathological alterations in the gill and fin of Anabas testudineus, after infection with myxozoan parasites along with an ultrastructural study using scanning electron microscopy, which has not been previously studied. Therefore, this investigation also allows some insight into the previously unrecorded tissue-level alteration of infected host organs due to parasitic infestation.