Journal of Morphology最新文献

The cephalic musculature of the Pacman catfish Lophiosilurus alexandri (L. alexandri) is described and compared with Pimelodus maculatus, Pimelodus microstoma, Pseudopimelodus mangurus (P. mangurus), Batrochoglanis labrosus (B. labrosus), and Lophiosilurus fowleri (L. fowleri). Besides the distinguished Pacman catfish head shape, which is strongly depressed, broad, and with a large mouth, we hypothesize that the gross morphology of the musculature is related to the phylogenetic background. A phylogenetic analysis of selected characters evidenced three putative synapomorphies for the family Pseudopimelodidae, three for the subfamily Batrochoglaninae, three for the genus Lophiosilurus, two autapomorphies for L. alexandri, one for L. fowleri, one for B. labrosus, and five for P. mangurus. The absence of the retractor tentaculi is interpreted as a putative synapomorphy of Pseudopimelodidae and Pimelodidae. The rounded adductor mandibulae emerge as the predominantly voluminous musculature in L. alexandri and other Pseudopimelodidae, a conspicuous synapomorphy of the family. Profound differences were observed when comparing the cephalic musculatures of L. alexandri with Lophius piscatorius and Chaca bankanensis, which are unrelated species with similar body morphology and ambush behavior. The morphology of cephalic musculature highlights the plasticity of the musculature function and the closer relationship with the phylogenetic history of species and lineages.

The skeleton is a rich source of characters used in phylogenetic studies of teleost fishes. However, the development of bones was studied in a limited number of species and few studies have been published describing the ontogeny of the Characiformes skeleton. We provide the first complete description of the skeleton ontogeny of an anostomid, Leporinus oliveirai, based on specimens bred in captivity and sampling the first 60 days post-hatching, with sizes ranging from 3.8 mm (notochord length, NL) to 33.2 mm (standard length, SL). Sixty-three specimens were cleared and double stained and subsequently dissected and photographed. The developmental sequence of 141 bony elements is documented. Photography of all anatomical complexes is presented during the development. The first bone to develop is the cleithrum (5.1 mm NL) and the last ones are infraorbitals 4, 5 and 6, extrascapular and sclerotic bones (27.2-29.7 mm SL), similar to what is observed in the development of other characiforms. The main discoveries are numerous conical teeth on the premaxilla and dentary from 5.1 mm NL to 10.4 mm SL that are replaced with three or four large incisiform multicuspid teeth, that become unicuspid in juveniles and adults. The infraorbitals 4 and 5, seen only in juveniles, develop fused, a condition that is in contrast to most anostomids. The autopalatine cartilage begins its development straight, becoming curved during development. The developmental sequence is compared with other Characiformes and the unique characteristics of Anostomidae are discussed concerning the phylogenetic relationships among the family members.

The order Hemiptera s. lat. (=Homoptera + Heteroptera), comprising approximately 140 families and 70,000 species, is the largest order among hemimetabolous insects in terms of species diversity. A key trait shared among these insects is their specialized piercing-sucking mouthparts, which have been considered an important factor in their diversification. However, knowledge of how these characteristic hemipteran mouthparts form during embryogenesis remains limited and biased toward model species. In this study, we observed the embryonic development of the heteropteran insect Appasus japonicus (Belostomatidae). We divided its embryonic development into 10 stages and provided a detailed description. Additionally, we examined its developmental processes and compared them with the embryogenesis of closely related groups. As a result, we confirmed that (1) the maxillary plate, one of the structures forming the heteropteran mouthparts, is homologous to the maxillary palp, and (2) most parts of the stylet-like mandibles and maxillae are housed within the labial palp.

Information detection affects physiological performance and behaviour and is vital to survival and fitness. Despite the recognised importance of sensory adaptations in information acquisition and manipulation, many forms of sensory variation—from within individuals to between species—remain underexplored. To better understand the role of information in evolution, it is important to examine sensory variation as part of a cohesive framework of sensory diversity. Using the decapod claw, a structure well-recognised for its morphological variation, we investigated sensory diversity at the intraspecific level by assessing heterochely and sexual dimorphism in the chelar morphologies of Pagurus bernhardus hermit crabs. We employed a novel methodology using scanning electron microscopy (SEM) to assess moulted chelar tissue from both the major and minor claws. The shape, size, and sensillation (i.e., the distribution and abundance of sensilla) of both chelipeds were examined by geometric morphometric landmark analysis (GMLA), generalised Procrustes analysis (GPA), and linear mixed effects models. Hermit crabs exhibited heterochely and sexual dimorphism in both gross and sensory chelar morphologies. Sexual dimorphism was greater in the sensory morphology of the major claw, suggesting sex-based sensory specialisations, likely due to differences in mating roles and behaviours. In contrast, the minor claw's sensory morphology lacked sexual dimorphism, suggesting the sensory role of this appendage is equally important for both sexes. Our results highlight sensory variation as a fundamental aspect of functional morphology and emphasise the need to consider sexual dimorphism and body asymmetry in information acquisition. These findings contribute to a broader framework for studying sensory diversity, underscoring the importance of integrating sensory morphology, function, and ecology to fully understand the evolutionary implications of sensory specialisations.

We present, for the first time, the suction feeding behavior of the tadpole of Dendropsophus cerradensis (Hylidae, Dendropsophini), along with a detailed description of its external morphology, buccopharyngeal cavity, and musculoskeletal system. The tadpole exhibits a depressed body, anteriorly positioned nostrils, a modified oral disc (completely covered by external folds), and a low tail, resembling other members of the D. microcephalus group. The buccopharyngeal cavity is reduced in features, with internal nares positioned at an acute angle and covered by prenarial papillae, exclusive for this species. Muscle insertion patterns are generally consistent with other Dendropsophini tadpoles, except for the insertion of the m. levator mandibulae longus profundus on Meckel's cartilage. The feeding behavior is characterized by the use of an oral tube that protrudes exclusively during predation. This mechanism may be associated with robust mandibular and hyoid musculature, as well as a modified cranial structure—including a unique suprarostral element, quadrangular muscular processes, robust ceratohyals, and a reduced branchial basket in the hyobranchial skeleton—which enables fast suction movements. This study presents a previously unknown aspect of the protractile oral tube and feeding behavior of the D. microcephalus group, providing new insights into the morphology and feeding behavior of the group.

Investigating the developmental patterns of extinct species provides valuable insights into their anatomy, biology and ecomorphological adaptations. Research on the ontogeny of non-mammaliaform cynodonts has offered significant contributions to our understanding of these aspects. Here, we aim to describe and discuss the intraspecific and ontogenetic variation of the skull of the Brazilian traversodontid Siriusgnathus niemeyerorum (Candelária Sequence, Upper Triassic). We evaluated an ontogenetic series of the species through qualitative comparison and allometric analyses using cranial measures. Our findings reveal several trends during skull growth, including a relative increase in rostrum length, a relative decrease in orbit size, and changes in the zygomatic arch and temporal fenestra proportions. These patterns, when analyzed in the context of the adductor musculature, may be correlated with changes in feeding behaviour, similar to those described for the gomphodontosuchine Exaeretodon argentinus. We also report changes in cranial ornamentation, bone fusion, and suture complexity throughout ontogeny. Overall, this study provides a greater understanding of the cranial ontogenetic patterns of S. niemeyerorum, contributing to the knowledge of its intraspecific variation. The possible ecological implications of these findings highlight the importance of ontogenetic studies for elucidating the biology of extinct taxa.

Larvae of the black soldier fly, Hermetia illucens, are currently intensively studied, owing to their potential importance in various fields such as waste bioconversion, forensic entomology, and food supply for humans and life stock. Despite the increased attention, a detailed anatomical documentation of the larvae using modern methods is lacking, and even statements on the number of larval stages are contradictory. Misinterpretations of the ontogeny of this species have led to frequent erroneous identifications of the last larval instar as pupa. Consequently, many studies with a focus on larval morphology have neglected the last larval stage. In this contribution, we describe and document morphological changes of the larval head throughout the postembryonic development, with emphasis on the transition between the last two instars. This is characterized by a crucial behavioral shift from a feeding stage to a stage of increased vagility. We show that different cephalic structures undergo major changes, especially the mandibulo-maxillary complex and the digestive tract, and associated muscles. Our measurements of the body length and the length of the head capsule tentatively confirm that the larval development of H. illucens passes through seven instars.