Digital dissection of the head of the frogs Calyptocephalella gayi and Leptodactylus pentadactylus with emphasis on the feeding apparatus

Abstract

Micro‐computed tomography (microCT) of small animals has led to a more detailed and more accurate three‐dimensional (3D) view on different anatomical structures in the last years. Here, we present the cranial anatomy of two frog species providing descriptions of bone structures and soft tissues of the feeding apparatus with comments to possible relations to habitat and feeding ecology. Calyptocephalella gayi, known for its aquatic lifestyle, is not restricted to aquatic feeding but also feeds terrestrially using lingual prehension. This called for a detailed investigation of the morphology of its feeding apparatus and a comparison to a fully terrestrial species that is known to feed by lingual prehension such as Leptodactylus pentadactylus. These two frog species are of similar size, feed on similar diet but within different main habitats. MicroCT scans of both species were conducted in order to reconstruct the complete anatomical condition of the whole feeding apparatus for the first time. Differences in this regard are evident in the tongue musculature, which in L. pentadactylus is more massively built and with a broader interdigitating area of the two main muscles, the protractor musculus genioglossus and the retractor musculus hyoglossus. In contrast, the hyoid retractor (m. sternohyoideus) is more massive in the aquatic species C. gayi. Moreover, due to the different skull morphology, the origins of two of the five musculi adductores vary between the species. This study brings new insights into the relation of the anatomy of the feeding apparatus to the preferred feeding method via 3D imaging techniques. Contrary to the terrestrially feeding L. pentadactylus, the skeletal and muscular adaptations of the aquatic species C. gayi provide a clear picture of necessities prescribed by the habitat. Nevertheless, by keeping a certain amount of flexibility of the design of its feeding apparatus, C. gayi is able to employ various methods of feeding.

A spectacular new species ofHyloscirtus(Anura: Hylidae) from the Cordillera de Los Llanganates in the eastern Andes of Ecuador

“…Additionally, the skull of the holotype of the new species was rendered and segmented to separate and color individual bones in three dimensions using Amira visualization software (FEI, Thermo Fisher Scientific, Waltham, MA, USA). Osteological terminology follows Trueb (1973) , Duellman & Trueb (1994) , Coloma et al (2012) , Kunisch et al (2021) , Reyes-Puig et al (2021) . For the description of the cranium and the osteology of the hand, we followed the proposal of Coloma et al (2012) .…”

The SmARTR pipeline: a modular workflow for the cinematic rendering of 3D scientific imaging data

“…Indeed, the different SmARTR networks offer a wide array of visualization options, each with numerous potential applications, designed to cover a wide spectrum of specific user needs (Table 1 and Supplemental Methods). Single-or multi-volume/-organ visualization is essential for understanding biological complexity, improving qualitative descriptions and/or complementing quantitative analyses of species-specific anatomical traits in both extant and extinct species 30,33,47,122,124,134,135,137,[149][150][151][152][153] . Especially, detailed visualizations of animal visceral organs, their reciprocal relationships, and their distribution within skeletal elements, as well as isolated organs or animal parts (Figure 4) can be easily obtained using either the SmARTR_Multi-Mask_Volume or SmARTR_Multi-Independent_Volume network (Table 1 and sections 3-4 of Supplemental Methods).…”