Journal of Morphology最新文献

The study of ant morphology is advancing through parallel insights provided by phylogenomics—which provides a statistically robust basis for comparison and evolutionary inference—and phenomics via the application of microcomputed tomography (µ-CT) for the efficient and precise documentation of anatomy. The information provided by µ-CT is complex and rich, allowing for the quantification of geometry and biomechanically relevant variables, as well as comparative morphology via 3D rendering. Recently, the complete musculature of the thorax, propodeum, and legs was documented for the first time in an ant (Formica rufa L.). Here, we provide a detailed comparison of those findings for Protanilla lini Terayama, 2009 (Leptanillinae), representing the Leptanillomorpha, a clade putatively sister to all other living ants. Using µ-CT, computer-based reconstruction, and scanning electron microscopy (SEM), we observe a novel series of morphological features that are plausibly part of the groundplan of the Formicidae. For several of these features, we provide new anatomical concepts and terms, with special discussion of the pronotum, promesothoracic articulation, and metapleural gland region. We also observe characters that are likely correlated with specialized subterranean habits, including the increased flexibility of the promesothoracic articulation, the slender shape of the mesosoma, a simplified vestiture of short setae, and depigmentation. Mesosomal skeletomusculature in P. lini appears to be plesiomorphic relative to other Leptanillomorpha, resembling the putative ancestral condition for the Formicidae. An exception lies in the lack of cervical muscle (Idlm1) in Protanilla that is present in almost all other insects for which this character has been sampled. With this study of P. lini, we are one step closer to realizing the complete set of defining features and variation of the ant mesosoma.

Recent studies have emphasized the ecological significance of bats as insect regulators. This recognition has prompted an increased scientific interest in Mormoops megalophylla, a notable neotropical insectivorous bat species. The extant literature on its biology remains limited and substantial knowledge gaps persist, particularly regarding its reproductive cycle. This study sought to examine morphological and histological variations in the reproductive organs of male and female M. megalophylla over the annual cycle to elucidate the stages of its reproductive process. Over the course of the year, five sexually mature individuals of each sex were sampled monthly, culminating in a total of 120 specimens, to document variations in external sexual characters, the testes, epididymides, uterus, and ovaries; all sampled individuals underwent morphological, morphometric, and histological analyses. The findings indicate that M. megalophylla has migratory testes with seasonal spermatogenesis occurring from October to December, a bicornuate uterus, and a single folliculogenic period that is synchronized with spermatogenesis. This suggests a monoestrous, seasonal, and synchronous reproductive pattern. At the population level, copulation occurs between November and December, gestation occurs between December and May, and parturition occurs between late May and early June. The lactation period extended from June to September.

Leporinus oliveirai is a recently described species from Serra do Cachimbo, Pará State, Brazil, notable for its small size and vibrant coloration. This species has been successfully reproduced in captivity and is commercially traded internationally. Herein, we describe the early development of Leporinus oliveirai, documenting its external morphology with photographs and illustrations. The ontogeny of L. oliveirai is compared with that of other anostomids for which ontogenetic data are available, and developmental patterns are described for the family. In Anostomidae, the critical processes associated with the transition to exogenous feeding occur within the first 5 days post-hatching. Fin formation occurred in two distinct phases: the anal, dorsal, caudal, and adipose fins developed first, followed by the pelvic and pectoral fins. The sequence of fin ossification in anostomids is generally consistent with patterns described for other Characiformes. Additionally, a marked increase in growth rate and indications of allometric growth were observed following notochord flexion.

Appendicularia comprises about 70 holoplanktonic species traditionally classified in three families: Oikopleuridae, Fritillariidae, Kowalevskiidae. Despite their eminent phylogenetic position and their important role in ocean ecosystems, most research focuses on the model organism Oikopleura dioica while the diversity of appendicularians remains underexplored. Here, we present a comparative morphological analysis of appendicularian endostyles, a pharyngeal gland homologous to the vertebrate thyroid. Based on light- and transmission electron-microscopical investigations in 12 species representing seven (of 15) genera from all three family-level taxa, we describe the 3D-anatomy of endostyles, histologically recognizable cell-types, and discuss our findings in a cladistic framework. We identified seven different cell types arranged in species specific patterns, including the formerly unrecognized ‘bright cells’. Two ciliary bands – the peripharyngeal band and the retropharyngeal band – are associated with the endostyles. Outgroup comparison indicates that repeated apomorphic reductions of cell types, rows of cells, the retropharyngeal band, and the complete endostyle occurred within Appendicularia. We propose a phylogenetic hypothesis that suggests that “Oikopleuridae” is a paraphyletic grouping and supports an evolutionary scenario with multiple reductions functionally related to the evolution of the external filter house of appendicularians. While we document the diversity of endostyle anatomy, more detailed cladistic analysis, including other organ systems, is needed to resolve the phylogenetic relationships and to understand the evolution of appendicularian taxa.

The stifle joint is among the most commonly injured joints in dogs. Detailed functional information is required to identify the causes of damage and determine the most appropriate treatment strategy. The lateral condyle of the femur and its attaching structures play an important role in joint stability, which is essential for proper joint movement. The long digital extensor and popliteus muscles originate from the lateral condyle, and their functions have not been described properlyresulting in contrasting functional interpretations. In this study, we suggest new functional hypothesses for these muscles based on their origin coordinates from the lateral condyle in dogs. The popliteus muscle may act as either an extensor or a flexor depending on the stifle angle during the stance phase, in addition to facilitating rotational movement. The long digital extensor muscle functions as an extensor of the joint and may prevent the lateral condyle from slipping caudally during stifle extension. It may also help prevent cranial tibial thrust on the lateral side of the tibial plateau during extension. From a parcticioner point of view we suggest that, during the stifle surgery, the muscles are preserved as much as possible.

Over a century ago, Dutch anatomist and geologist Eugène Dubois discovered the famous “Java man” and associated mammals in Java. His collection continues to be widely recognised for its significance to palaeontology and palaeoanthropology. Mammal fossil remains from Dubois’ collections have been essential for understanding faunal migrations driven by Quaternary glacial cycles from Southeast Asia to the Sunda Shelf and beyond, and thus the evolution and present distribution of mammals across Island Southeast Asia (ISEA). An important group are the Suinae (pigs). Most extant Eurasian Suinae species belonging to the genus Sus, except the widely distributed Sus scrofa, are mostly found in ISEA, and represent an example of species radiation. Knowledge of the origin, migration, and evolution of the genus Sus is limited, and studies on ecomorphological disparity and phylogeny of fossil Suinae are scarce. Considering the importance of ISEA in the evolutionary history of the genus, a detailed understanding of the fossil Sus species from the region is key to understanding the origin, dispersal, and evolution of Sus. Here, I focus on the anatomy of two endemic species from the Middle Pleistocene of Java (Indonesia), S. brachygnathus and S. macrognathus. A detailed anatomical description and morphological comparison between these species and extant and fossil suids are provided, including hitherto undescribed features of two species in the context of ecomorphology. Finally, aspects of the phylogenetic relationships of both species are discussed in relation to insular evolutionary trends. The importance of these fossil Sus remains from Java lies not only in their key role to understanding the evolutionary history and diversification of Sus, but also in providing insights into the evolutionary trends of insular pigs.