Nancy L. Staub

Although they potentially share ancestral heritage with the mental gland, salivary glands have not been studied thoroughly in plethodontid salamanders. Previous enzymatic studies in other families of amphibians have identified the presence of proteases and amylases, which are thought to be secreted from the intermaxillary gland and lingual gland. However, no such studies have been conducted in plethodontid salamanders, and the enzyme contents of these glands are poorly understood. We used immunohistochemistry to identify the presence of amylase, protease, and lipase in the glands of three species of Eurycea . Histological descriptions—based on hematoxylin and eosin staining—of the studied glands are also included. We found that amylase and protease were present in the intermaxillary gland and in the surface epithelium of the tongue. The lingual gland was notably lacking salivary enzymes. Preliminary results indicate the possible presence of lipase in the mouth of plethodontid salamanders. This study confirms the intermaxillary gland as a major salivary organ, while contrasting with the previous understanding of the amphibian lingual gland.

Ichthyology & Herpetology (formerly Copeia) publishes work on the biology of fishes, amphibians, and reptiles, or work using those organisms as models for testing hypotheses of broad significance.

For over a century researchers have marveled at the square‐shaped toe tips of several species of climbing salamanders (genus Aneides ), speculating about the function of large blood sinuses therein. Wandering salamanders ( Aneides vagrans ) have been reported to exhibit exquisite locomotor control while climbing, jumping, and gliding high (88 m) within the redwood canopy; however, a detailed investigation of their digital vascular system has yet to be conducted. Here, we describe the vascular and osteological structure of, and blood circulation through, the distal regions of the toes of A. vagrans using histology in tandem with live‐animal videos. Specifically, we sectioned a toe of A. vagrans at 0.90 μm, embedded it in Spurrs resin, and stained the tissue with toluidine blue. An additional three toes were sectioned at 10 μm, embedded in paraffin, and after sectioning and mounting, treated with Verhoeff and Quad stains. For living salamanders, we recorded real‐time videos of blood flowing within individual toes upon a translucent surface oriented both horizontally (0°) and vertically (90°) to simulate both prostrate and vertical clinging scenarios, then analyzed the image sequences using ImageJ. We found that the vascularized toe tips have one large sinus cavity that is divided more proximally into two chambers via a septum, and there are mucous and granular glands in the dorsal and dorsolateral integument of the digit tips. Live‐animal trials revealed variable sinus‐filling both within and between toes, seemingly associated with variable pressure applied to the substrate when standing, stepping, clinging, and climbing. We conclude that A. vagrans , and likely other climbing salamanders, can functionally fill, trap, and drain the blood in their vascularized toe tips to optimize attachment, detachment, and complex arboreal locomotion (e.g., landing after gliding flight). Such an adaptation could provide insights for bioinspired designs.

Solidarity and critical hope support faculty and staff who wish to accompany students, read the current reality of their experience, and imagine new practices that can rectify injustices and promote access and belonging. Here, we describe an example of this praxis by responding to student concerns about injustices in a course registration process. With some exceptions, undergraduates at this institution register for classes according to their earned college credits. At first glance, this meritocratic system shows care to students by recognizing their hard work. However, our analysis shows that it also discriminates against underserved groups of students. Using 10 years of course registration data, we compared assigned course registration periods between different student populations. The current registration process privileges white-identifying students over those identifying as African American/Black, Hispanic/Latino(a), Native American/Alaskan Native/Pacific islander, Asian, or two or more races. Pell grant-eligible and first-generation students also registered later compared to their peers; these inequities persisted throughout their college career. These results demonstrate an example of critical hope praxis for Jesuit institutions in which we accompany students and investigate policies that appear to preference cura apostolica (care for the institution in maintaining the status quo) at the expense of cura personalis.

Derived monomorphism is a condition in which males and females are phenotypically similar, but the similarity is derived. Derived monomorphism typically evolves from sexual dimorphism or from a different monomorphic state. We examined the hormonal basis of derived monomorphism in the salamander genus Aneides (Plethodontidae). We reject our hypothesis that circulating levels of androgens explain the derived traits, such as enlarged jaw musculature, in females (some would call them “male‐like traits”). There was no clear pattern of differences in androgen levels or degree of dimorphism in androgen levels, between the sexually dimorphic Aneides hardii and the other, derived monomorphic, species studied. Concentrations of testosterone and dihydrotestosterone were higher in males than in females in all species examined. The degree of sexual dimorphism in androgen level was also consistent among the species studied. Levels of androgens in female plethodontids have not been previously reported.

In May 2023, herpetologists from six countries converged at the 8th Conference on the Biology of Plethodontid Salamanders in Hammond, Louisiana to share their latest cutting-edge research. The conference was hosted by the Department of Biological Sciences at Southeastern Louisiana University. Dr. Richard Bruce was the honoree. The presentations covered a diverse array of topics from gene expression to behavior to speciation, illustrating the value of plethodontid salamander biology to a range of disciplines. This special issue of Herpetologica includes 16 papers highlighting a range of research on plethodontids and encouraging new approaches to tackle old and new questions.

Male Ensatina eschscholtzii do not have a mental gland, a macrogland used by males during courtship that is considered an ancestral character of plethodontids. We tested whether males and females have nonmental courtship glands associated with the integument of the rostrum and mentum (chin). We found that both male and female E. eschscholtzii possess courtship-like integumentary glands (modified granular glands) in the upper labia extending dorsally along the rostrum and lower labia extending ventrally across the mental region. These glands are sexually dimorphic in size (larger in females) and react positively with periodic acid–Schiff. We hypothesize that these glands are involved in courtship through production of pheromones that may or may not be similar to pheromones produced in courtship glands of other plethodontid salamanders. These rostral glands are structurally and chemically unique in comparison with glands of the rostrum that empty along the length of nasolabial grooves (nasolabial glands) of Ensatina, which do not appear to be involved in pheromone production. Both females and males have relatively few traditional mucous glands throughout the skin in comparison with other species of plethodontids, although some clusters are identified at the anterior edges of the labia.

While sexual dimorphism has long received special attention from biologists, derived monomorphism, the condition in which both males and females express similar derived features has been less well studied. Historically, the appearance of “male-like” features in females has been explained by the genetic correlation between the sexes. Recent work emphasizes the importance of studying the independent selective forces on both females and males to understand sexual dimorphism. Sexual dimorphism and derived monomorphism in the genus Aneides are examined in light of predictions of social selection. Aneides hardii shows the greatest degree of sexual dimorphism in snout–vent length and head width, with the other species of Aneides less sexually dimorphic. This reduced dimorphism, however, is not a return to an ancestral monomorphic state, but rather exemplifies derived monomorphism because females express traits that were limited in expression to males of ancestral species. Instead of calling these “male-typical” traits in females, I suggest the term “derived monomorphic” traits as these traits are typical in these females, and “derived monomorphic” can apply to both sexes. Increased attention to studying the patterns and ecological significance of derived monomorphism will shed light on the underlying selective forces, including sexual selection, on both females and males.

Synopsis: Courtship behavior in salamanders is often complex and involves well-documented communication from males to females in multiple sensory modalities. Historically, behaviors exhibited during the major stages of courtship have been predominately framed as a male acting and signaling to “persuade” a passive female to participate in courtship and remain with him until sperm release is completed. In this review, we use courtship descriptions for lungless salamanders (Plethodontidae) as a case study to illustrate this historical bias of a male-centered perspective. We then re-examine the literature and summarize the many ways females are active participants during plethodontid courtships. We also relate female behaviors to the types of female-to-male communication that may occur. For example, females have been documented to approach a male and initiate courtship, participate in mutual head rubbing, and step astride the male’s tail to begin the tail-straddling walk (a key courtship behavior observed in all plethodontids). Additionally, females have glands that may produce chemical signals that males respond to during courtship. We conclude that communication during courtship is more accurately described as a two-way interaction where each partner’s behavior is coordinated with the other’s via multi-modal signaling. Shifting the lens through which we view courtship and behavior provides insight into which female behaviors and anatomical features are most likely to be used for communication with males.

Leading scientists recognize the need to be proactive about educational reform. To address some of the challenges of teaching K-6 science, our outreach program, Science in Action! (SIA!), pairs undergraduates with K-6 classrooms to do hands-on, inquiry-based science. Our goal is to increase science literacy in our community through developing the science understanding and teaching skills of pre-service teachers, recruit more STEM majors into teaching careers, and promote enthusiasm and curiosity in the science K-6 classroom. We describe Science in Action! and describe the effect participation in the program has on undergraduates. In particular, we asked how participation effects pre-service elementary school teachers, who generally have a limited science background, and science majors, who are in the process of deciding a future career path. Pre-service teachers reported that their participation in SIA! deepened both their understanding of the scientific method and science content, as well as increased their confidence in being able to teach science. The number of science majors seriously considering a teaching career increased significantly after participating in Science in Action!