Journal of Morphology

Weidhase, Michael; Bleidorn, Christoph; Helm, Conrad

doi: 10.1002/jmor.20340pmid: N/A

Cover illustration. Cirratulidae are a family of marine sedentary annelids with a remarkable regenerative ability. In this issue of the Journal of Morphology,Weidhase et al. (pp. 1418–1430, 10.1002/jmor.20316) investigated the structure of musculature and nervous system in intact and anterior regenerating individuals of Cirratulus cf. cirratus using confocal laser‐scanning microscopy. Additionally, implications for general regeneration patterns in annelids were discussed. The cover image is a depth coded confocal maximum projection of the musculature of the anterior end in lateral view, showing the two layers of the body wall musculature and further muscle fibers of the parapodia, the tentacles, and the mouth opening.

Janis, Christine M.; Figueirido, Borja

doi: 10.1002/jmor.20303pmid: 24934132

Carnivorous mammals use their forelimbs in different ways to capture their prey. Most terrestrial carnivores have some cursorial (running) adaptations, but ambush predators retain considerable flexibility in their forelimb movement, important for grappling with their prey. In contrast, predators that rely on pursuit to run down their prey have sacrificed some of this flexibility for locomotor efficiency, in the greater restriction of the forelimb motion to the parasagittal plane. In this article, we measured aspects of the forelimb anatomy (44 linear measurements) in 36 species of carnivorous mammals of known predatory behavior, and used multivariate analyses to investigate how well the forelimb anatomy reflects the predatory mode (ambush, pursuit, or pounce‐pursuit). A prime intention of this study was to establish morphological correlates of behavior that could then be applied to fossil mammals: for this purpose, five individuals of the recently extinct thylacine (Thylacinus cynocephalus) were also included as unknowns. We show that the three different types of predators can be distinguished by their morphology, both in analyses where all the forelimb bones are included together, and in the separate analyses of each bone individually. Of particular interest is the ability to distinguish between the two types of more cursorial predators, pursuit and pounce‐pursuit, which have previously been considered as primarily size‐based categories. Despite a prior consideration of the thylacine as a “pounce‐pursuit” or an “ambush” type of predator, the thylacines did not consistently cluster with any type of predatory carnivores in our analyses. Rather, the thylacines appeared to be more generalized in their morphology than any of the extant carnivores. The absence of a large diversity of large carnivorous mammals in Australia, past and present, may explain the thylacine's generalized morphology. J. Morphol. 275:1321–1338, 2014. © 2014 Wiley Periodicals, Inc.

Smith, Matthew T.

doi: 10.1002/jmor.20305pmid: 24934273

Gape‐limited predators are restricted in the shape and size of prey items they can ingest by their trophic morphology. Evolutionary theory predicts that gape‐limited predators, such as rattlesnakes, should possess plasticity in their trophic morphology to allow them to respond to environmental cues about their prey base. This study examined the effects of two possible influences over trophic morphology in the pit‐viper Crotalus viridis viridis. Snakes from six litters were exposed to diet manipulations performed over 480 days. By day 480, snakes from two prey‐size treatments exhibited significantly different head shapes. Snakes reared on whole rodents had broader heads, whereas snakes force‐fed homogenized prey had narrower heads. Shape differences varied among litters, suggesting that not all litters responded the same to diet manipulations. Results suggest that trophic morphology of rattlesnakes is plastic, at least in some litters, and can be induced by prey items. J. Morphol. 275:1339–1348, 2014. © 2014 Wiley Periodicals, Inc.

Gilis, Melany; Meibom, Anders; Domart‐Coulon, Isabelle; Grauby, Olivier; Stolarski, Jarosław; Baronnet, Alain

doi: 10.1002/jmor.20307pmid: 24966116

Calcium carbonate biomineralization of scleractinian coral recruits is fundamental to the construction of reefs and their survival under stress from global and local environmental change. Establishing a baseline for how normal, healthy coral recruits initiate skeletal formation is, therefore, warranted. Here, we present a thorough, multiscale, microscopic and spectroscopic investigation of skeletal elements deposited by Pocillopora damicornis recruits, from 12 h to 22 days after settlement in aquarium on a flat substrate. Six growth stages are defined, primarily based on appearance and morphology of successively deposited skeletal structures, with the following average formation time‐scales: A (<24 h), B (24–36 h), C (36–48 h), D (48–72 h), E (72–96 h), and F (>10 days). Raman and energy dispersive X‐ray spectroscopy indicate the presence of calcite among the earliest components of the basal plate, which consist of micrometer‐sized, rod‐shaped crystals with rhomboidal habit. All later CaCO3 skeletal structures are composed exclusively of aragonite. High‐resolution scanning electron microscopy reveals that, externally, all CaCO3 deposits consist of <100 nm granular units. Fusiform, dumbbell‐like, and semispherulitic structures, 25–35 µm in longest dimension, occur only during the earliest stages (Stages A–C), with morphologies similar to structures formed abiotically or induced by organics in in vitro carbonate crystallization experiments. All other skeletal structures of the basal plate are composed of vertically extending lamellar bundles of granules. From Stage D, straight fibrils, 40–45 nm in width and presumably of organic composition, form bridges between these aragonitic bundles emerging from the growing front of fusing skeletal structures. Our results show a clear evolution in the coral polyp biomineralization process as the carbonate structures develop toward those characterizing the adult skeleton. J. Morphol. 275:1349–1365, 2014. © 2014 Wiley Periodicals, Inc.

Castillo, Daniela L.; Flores, David A.; Cappozzo, Humberto L.

doi: 10.1002/jmor.20309pmid: 25052760

The aim of this work was to study the postnatal ontogenetic development of Pontoporia blainvillei skull, identifying major changes on shape, and relating them to relevant factors in the life history of the species. We analyzed a complete ontogenetic series (73♂, 83♀) with three‐dimensional geometric morphometric techniques. Immature dolphins showed a very well‐developed braincase and a poorly developed rostrum, and the principal postnatal changes affected the rostrum and the temporal fossa, both structures implied functionally to the feeding apparatus, thus suggesting a specialized mode for catch fast prey in P. blainvillei. Osseous elements associated with sound production were already well developed on immature dolphins, suggesting the importance of this apparatus since the beginning of postnatal life. Sexual dimorphism was detected on both shape and size variables. Females were bigger than males, in accordance with previous studies. Shape differences between sexes were found on the posterior part of premaxillaries and external bony nares (P < 0.01), suggesting that this sexual dimorphism is related to differences on vocalization capabilities. J. Morphol. 275:1366–1375, 2014. © 2014 Wiley Periodicals, Inc.

Walker, Eric A.; Townsend, Victor R.

doi: 10.1002/jmor.20310pmid: 25052845

The external morphology of the penis is an important source of systematic characters in phylogenetic studies of harvestmen. Modern taxonomic studies generally include micrographs generated by scanning electron microscopy (SEM) to illustrate penis morphology. In contrast, the external morphology of the ovipositor has largely been ignored for harvestmen belonging to the suborder Laniatores. Comparative studies of ovipositor microanatomy using SEM are especially lacking for species belonging to the superfamily Gonyleptoidea. In an effort to determine if the ovipositor could be a useful source of informative characters for these harvestmen, we investigated interspecific variation in the external morphology of the ovipositor for 14 species from the family Cosmetidae. Our SEM‐based study revealed that the external surface of the distal tips of the ovipositors of most species was generally divided into four symmetrical lobes, although we observed a bilobed condition in Erginulus clavotibialis and Erginulus subserialis. The distal surfaces were also generally smooth, with the exception of the ovipositor of Erginulus weyerensis, which featured small surface setae. In addition, we observed considerable interspecific variation in the morphology of the peripheral setae on the distal tip, especially with respect to relative size, morphology of the shaft, and number, symmetry, and shapes of the distal tips. The functional significance, if any, of variation in the structure of the peripheral setae is unclear. Additional behavioral studies of copulation and oviposition are needed to determine the functional relationships between reproductive morphology and behavior. The morphological variation that we observed suggests that future taxonomic studies of cosmetid harvestmen, and potentially other gonyleptoidean taxa, would benefit from the inclusion of descriptions of ovipositor morphology. J. Morphol. 275:1376–1385, 2014. © 2014 Wiley Periodicals, Inc.

Rodriguez, Andrea L.; Townsend, Victor R.; Johnson, Megan B.; White, Tara B.

doi: 10.1002/jmor.20312pmid: 25046592

Scanning electron microscopy (SEM) is a useful tool for identifying interspecific variation in often overlooked structures that may represent useful sources for informative phylogenetic characters. In this study, we used SEM to compare the morphology of 12 cosmetid species from Central America, the Caribbean, and North America including multiple species for the genera Cynorta, Erginulus, and Paecilaema. To determine if microanatomical structures were unique to the cosmetid taxa under examination, we investigated the microanatomical structures of six additional species of gonyleptoidean harvestmen representing the families Agoristenidae, Cranaidae, Gonyleptidae, Manaosbiidae, and Stygnidae. Our results indicate that the shape of the ocularium (narrow, intermediate, or broad) did not vary within cosmetid genera, whereas the morphology of the rough pit glands on the eye mound varied considerably between species. Each cosmetid species had 10–20 rough pit glands on the ocularium whereas only the eye mounds of Avima intermedia (Agoristenidae) and Glysterus sp. (Gonyleptidae) had similar structures. With regards to the surface texture of the dorsal scutum, cosmetid harvestmen exhibited a rivulose‐microgranulate morphology (6 species), a microtuberculate‐rivulose‐microrgranulate morphology (4 species), or a microgranulate morphology (2 species). In contrast, each of the gonyleptoidean species exhibited a microgranulate pattern, with the exception of Stygnoplus clavotibialis, which had a rivulose‐microgranulate surface texture. For cosmetid harvestmen, we observed considerable interspecific variation in the shape and number of teeth on the fixed and moveable fingers of the male chelicerae. Similarly, we also observed interspecific variation in the distribution and shape of tubercles on the ventral and dorsal surfaces of the femur of the pedipalp. Overall, our results indicate that there are several microanatomical structures associated with the ocularium, dorsal scutum, male chelicera, and pedipalp that could represent informative phylogenetic characters in future taxonomic studies of cosmetid harvestmen. J. Morphol. 275:1386–1405, 2014. © 2014 Wiley Periodicals, Inc.

Uribe, Mari Carmen; Rosa‐Cruz, Gabino; García‐Alarcón, Adriana

doi: 10.1002/jmor.20315pmid: 25220154

Intraluminal gestation, as it occurs in viviparous goodeids, allows a wide diversity of embryo‐maternal metabolic exchanges. The branchial placenta occurs in embryos developing in intraluminal gestation when ovarian folds enter through the operculum, into the branchial chamber. The maternal ovarian folds may extend to the embryonic pharyngeal cavity. A branchial placenta has been observed in few viviparous teleosts, and there are not previous histological analyses. This study analysis the histological structure in the goodeid Ilyodon whitei. The moterno ovarian folds extend through the embryonic operculum and reach near the gills, occupying part of the branchial chamber. These folds extend also into the pharyngeal cavity. In some regions, the epithelia of the ovarian folds and embryo were in apposition, developing a placental structure in which, maternal and embryonic capillaries lie in close proximity. The maternal epithelium has desquamated cells which may enter through the branchial chamber to the pharyngeal cavity and the alimentary tract. The complex processes that occur in the ovaries of viviparous teleosts, and its diverse adaptations for viviparity, as the presence of branchial placenta, are relevant in the study of the evolution of vertebrate viviparity. J. Morphol. 275:1406–1417, 2014. © 2014 Wiley Periodicals, Inc.

Weidhase, Michael; Bleidorn, Christoph; Helm, Conrad

doi: 10.1002/jmor.20316pmid: 25088965

Annelids provide suitable models for studying regeneration. By now, comprehensive information is restricted to only a few taxa. For many other annelids, comparative data are scarce or even missing. Here, we describe the regeneration of a member of the Cirratulus cirratus species complex. Using phalloidin‐labeling and antibody‐stainings combined with subsequent confocal laser scanning microscopy, we provide data about the organization of body wall musculature and nervous system of intact specimens, as well as about anteriorly regenerating specimens. Our analyses show that C. cf. cirratus exhibits a prominent longitudinal muscle layer forming a dorsal muscle plate, two ventral muscle strands and a ventral‐median muscle fiber. The circular musculature forms closed rings which are interrupted in the area of parapodia. The nervous system of C. cf. cirratus shows a typical rope‐ladder like arrangement and the circumesophageal connectives exhibit two separate roots leading to the brain. During regeneration, the nervous system redevelops remarkably earlier than the musculature, first constituting a tripartite loop‐like structure which later become the circumesophageal connectives. Regeneration of longitudinal musculature starts with diffuse ingrowth and subsequent structuring into the blastema. In contrast, circular musculature develops independently inside the blastema. Our findings constitute the first analysis of regeneration for a member of the Cirratuliformia on a structural level. Summarizing the regeneration process in C. cf. cirratus, five main phases can be subdivided: 1) wound closure, 2) blastema formation, 3) blastema differentiation, 4) resegmentation, and 5) growth, respectively elongation. Additionally, the described tripartite loop‐like structure of the regenerating nervous system has not been reported for any other annelid taxon. In contrast, the regeneration of circular and longitudinal musculature originating from different groups of cells seems to be a general pattern in annelid regeneration. J. Morphol. 275:1418–1430, 2014. © 2014 Wiley Periodicals, Inc.

Felice, Ryan N.

doi: 10.1002/jmor.20321pmid: 25139752

Birds are capable of a wide range of aerial locomotor behaviors in part because of the derived structure and function of the avian tail. The tail apparatus consists of a several mobile (free) caudal vertebrae, a terminal skeletal element (the pygostyle), and an articulated fan of tail feathers that may be spread or folded, as well as muscular and fibroadipose structures that facilitate tail movements. Morphological variation in both the tail fan and the caudal skeleton that supports it are well documented. The structure of the tail feathers and the pygostyle each evolve in response to functional demands of differing locomotor behaviors. Here, I test whether the integument and skeleton coevolve in this important locomotor module. I quantified feather and skeletal morphology in a diverse sample of waterbirds and shorebirds using a combination of linear and geometric morphometrics. Covariation between tail fan shape and skeletal morphology was then tested using phylogenetic comparative methods. Pygostyle shape is found to be a good predictor of tail fan shape (e.g., forked, graduated), supporting the hypothesis that the tail fan and the tail skeleton have coevolved. This statistical relationship is used to reconstruct feather morphology in an exemplar fossil waterbird, Limnofregata azygosternon. Based on pygostyle morphology, this taxon is likely to have exhibited a forked tail fan similar to that of its extant sister clade Fregata, despite differing in inferred ecology and other aspects of skeletal anatomy. These methods may be useful in reconstructing rectricial morphology in other extinct birds and thus assist in characterizing the evolution of flight control surfaces in birds. J. Morphol. 275:1431–1440, 2014. © 2014 Wiley Periodicals, Inc.