Stem Anatomy of Uebelmannia (Cactaceae) — with Special Reference to Uebelmannia gummifera

The three species of Uebelmannia (Cactaceae: Cactoideae; endemic to Minas Cerais, Brazil) are noteworthy for their tough, bumpy stem surface and the presence of conspicuous mucilage cavities restricted to the outer part of the stems. The anatomy of the mature structures and their ontogeny was investigated from microtome sections. The uncommon surface relief is caused by groups of unequally elongated hypodermis cells. The mucilage cavities consist of solitary and considerably enlarged mucilage cells (U.buiningii and U. pectinifera). In U.gummifera groups of mucilage cells disintegrate and form large cavities which are finally united into longitudinal ducts. A comparison of these stem features with species of the superficially similar genera Islaya and Wigginsia (representing tribe Notocacteae), does not indicate a close phylogenetic relationship between Uebelmannia and members of tribe Notocacteae. Finally, some short comments touch on the adaptational aspect of the characteristic stem features of Uebelmannia.     

AutoCellRow (ACR) – A new tool for the automatic quantification of cell radial files in conifer images

Quantitative wood anatomy (QWA) is a growing field of dendrochronology that allows obtaining a large number of parameters as the number, size and spatial arrangement of cellular elements, elements that highlight the adjustments of trees to their environment. In this work, we presented the free/libre open-source software AutoCellRow (ACR), a ready-to-use tool for automatic QWA in conifers. The ACR analyzes radial files of cells on cross-sections views of tree rings and provides automatic measurements of different cell parameters (e.g., lumen radial diameter, double cell wall thickness and cell radial diameter) for each cell along the selected radial file. The ACR measurements are based on high performed image analysis of xylem cells. The accuracy of the software measurements was tested in cross-sections of five conifer species from a semi-arid area of southern Siberia, and compared with measurements obtained by a semiautomatic tool. Our results suggested high accuracy in the ACR cell traits measurements, facilitating and speeding the analysis of quantitative wood anatomy in conifers over radial files of cells.     

Not deconstructing serial homology,but instead,the a priori assumption that it generally involves ancestral anatomical similarity: An answer to Kuznetsov's paper

I am very thankful to Kuznetsov for his comments on our recent paper about serial structures published in this journal. I hope this is just the beginning of a much wider, and holistic, discussion on the evolution of serial homologous structures, and of so-called “serial structures” in general, whether they are truly serial homologs or the secondary result of homoplasy. Strangely, Kuznetsov seems to have missed the main point of our paper, what is particularly puzzling as this point is clearly made in the very title of our paper. For instance, he states that “Siomava et al. claim that the serial homologues are false because they are ancestrally anisomeric (dissimilar)' and that” Siomava et al., (Siomava et al., Journal of Morphology, 2020, 281, 1110–1132) expected that if serial homology was true, then the serial homologs would be identical at the start and then only diverge. “ However, our paper clearly did not state this. Instead, we stated that (a) serial homology is a real phenomenon, and (b) ancestral dissimilarity is actually likely the norm, and not the exception, within serial homology. In particular, our paper showed that, as clearly stated in its title and abstract, within the evolution of serial homologues these structures “many times display trends toward less similarity while in many others display trends toward more similarity, that is, one cannot say that there is a clear, overall trend to anisomerism.” Serial homology is therefore a genuine and much widespread phenomenon within the evolution of life in this planet. It is clearly one of the most important issues—and paradoxically one of the less understood, precisely because of the a priori acceptance of long-standing assumptions that have never been empirically tested, some of them repeated in Kuznetsov's paper—within macroevolution and comparative anatomy.     

Neotropical Hypericum irazuense shrubs reveal recent ENSO variability in Costa Rican páramo

Climate-vegetation relations in alpine systems play a pivotal role in regulating hydrology and have thus become a research priority in a context of ongoing climate change. In this paper, we investigate how one of the most dominant shrub species in alpine páramo ecosystems of Central America, Hypericum irazuense, responds to changes in precipitation, temperature and El Niño-Southern Oscillation. To this end, we performed dendrochronological and wood-anatomical analyses on H. irazuense to determine the limiting climatic factors driving shrub growth, using a bootstrapped correlation and response function analysis. To validate our results further, we also applied Structural Equation Models (SEM), an approach commonly used in ecology, so as to check for climate-growth relations which consider the control of ENSO on growth through its influence on various climatic parameters. Results support a relation between climate and annual growth of H. irazuense and demonstrate that the latter is sensitive to precipitation and temperature during boreal winters. In addition, we observe a statistically significant correlation between annual growth and La Niña events. The presence of annual growth rings holds H. irazuense as one in only few neotropical species suited for dendrochronological studies. Results of this study could thus contribute to an improved understanding of how changing climatic conditions affect the fragile and threatened páramo ecosystem and the ensuing services it offers in the form of hydrology regulation over the next decades.     

Challenges in identifying and interpreting organizational modules in morphology

Form is a rich concept that agglutinates information about the proportions and topological arrangement of body parts. Modularity is readily measurable in both features, the variation of proportions (variational modules) and the organization of topology (organizational modules). The study of variational modularity and of organizational modularity faces similar challenges regarding the identification of meaningful modules and the validation of generative processes; however, most studies in morphology focus solely on variational modularity, while organizational modularity is much less understood. A possible cause for this bias is the successful development in the last twenty years of morphometrics, and specially geometric morphometrics, to study patters of variation. This contrasts with the lack of a similar mathematical framework to deal with patterns of organization. Recently, a new mathematical framework has been proposed to study the organization of gross anatomy using tools from Network Theory, so‐called Anatomical Network Analysis (AnNA). In this essay, I explore the potential use of this new framework—and the challenges it faces in identifying and validating biologically meaningful modules in morphological systems—by providing working examples of a complete analysis of modularity of the human skull and upper limb. Finally, I suggest further directions of research that may bridge the gap between variational and organizational modularity studies, and discuss how alternative modeling strategies of morphological systems using networks can benefit from each other.     

The suction mechanism of the pipid frog,Pipa pipa (Linnaeus, 1758)

Most suction‐feeding, aquatic vertebrates create suction by rapidly enlarging the oral cavity and pharynx. Forceful enlargement of the pharynx is powered by longitudinal muscles that retract skeletal elements of the hyoid, more caudal branchial arches, and, in many fish, the pectoral girdle. This arrangement was thought to characterize all suction‐feeding vertebrates. However, it does not exist in the permanently aquatic, tongueless Pipa pipa , an Amazonian frog that can catch fish. Correlating high‐speed (250 and 500 fps) video records with anatomical analysis and functional tests shows that fundamental features of tetrapod body design are altered to allow P. pipa to suction‐feed. In P. pipa , the hyoid apparatus is not connected to the skull and is enclosed by the pectoral girdle. The major retractor of the hyoid apparatus arises not from the pectoral girdle but from the femur, which lies largely within the soft tissue boundaries of the trunk. Retraction of the hyoid is coupled with expansion of the anterior trunk, which occurs when the hypertrophied ventral pectoral elements are depressed and the urostyle and sacral vertebra are protracted and slide forward on the pelvic girdle, thereby elongating the entire trunk. We suggest that a single, robust pair of muscles adduct the cleithra to depress the ventral pectoral elements with force, while modified tail muscles slide the axial skeleton cranially on the pelvic girdle. Combined hyoid retraction, axial protraction, and pectoral depression expand the buccopharyngeal cavity to a volume potentially equal to that of the entire resting body of the frog. Pipa may be the only tetrapod vertebrate clade that enlarges its entire trunk during suction‐feeding.     

Variations in cruropedal musculature

The comparative anatomy of primate musculature has been established frequently from single specimens or small samples which are assumed to be typical for their species. However, a series of dissections of platyrrhine monkeys reported here reveals considerable variation within species and genera. Selected muscles of the leg and foot were examined and compared for discrete variations in attachments. The results were supplemented by observations in the anatomical literature for these and other primates. The range of variation reported across the order also presents itself as widespread polymorphism within most taxonomic groups, down to the species level. Since correlations with phylogeny and positional behavior are expressed only weakly, adaptationist explanations can account for only a part of the variation. Functional redundancy among the muscles supports the conclusion that the behavioral significance of the variations is slight. It is apparent that both genetic and nongenetic factors influence muscle form, and it is likely that observed polymorphisms have been characteristic of populations throughout primate evolution. Therefore, traits involving muscular form, especially as observed on small samples, within species, should be used cautiously in phyletic and adaptationist analyses.     

致倦库蚊主要组织结构的石蜡切片观察

【目的】蚊虫是传播人类多种疾病的重要媒介害虫, 对其组织形态学的认识是开展众多领域研究的基础。本文通过研究致倦库蚊Culex pipiens quinquefasciatus成虫组织结构及形态, 为媒介蚊虫的抗药性研究及有效防治提供基础材料。【方法】采用改进的石蜡切片法和HE染色, 结合活体内脏器官解剖及光学显微镜观察, 从形态学和组织学水平对致倦库蚊组织结构做详尽展示。【结果】获得结构完整、 染色清晰、 定位准确的消化排泄系统、 生殖系统、 神经系统、 呼吸系统等HE染色石蜡切片。【结论】探讨了改进制片和染色过程中一些步骤及注意事项。研究结果为利用原位杂交、 免疫组化等方法研究蚊虫体内抗药性基因的准确定位及基因功能分析提供了可靠的基础。