Skin glands of an aquatic salamander vary in size and distribution and release antimicrobial secretions effective against chytrid fungal pathogens

Amphibian skin is unique among vertebrate classes, containing a large number of multicellular exocrine glands that vary among species and have diverse functions. The secretions of skin glands contain a rich array of bioactive compounds including antimicrobial peptides (AMPs). Such compounds are important for amphibian innate immune responses and may protect some species from chytridiomycosis, a lethal skin disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). While the bioactivity of skin secretions against Bd has been assessed for many amphibian taxa, similar studies are lacking for Bsal, a chytrid fungus that is especially pathogenic for salamanders. We studied the skin glands and their potential functions in an aquatic salamander, the three-toed amphiuma (Amphiuma tridactylum). Skin secretions of captive adult salamanders were analyzed by RP-HPLC and tested against the growth of Bd and Bsal using in vitro assays. We found that compounds within collected skin secretions were similar between male and female salamanders and inhibited the growth of Bd and Bsal. Thus, skin secretions that protect against Bd may also provide protection against Bsal. Histological examination of the skin glands of preserved salamanders revealed the presence of enlarged granular glands concentrated within caudal body regions. A site of potential gland specialization was identified at the tail base and may indicate specialized granular glands related to courtship and communication.

Ultrastructure of spermatid development within the testis of the Yellow-Bellied Sea Snake, Pelamis platurus (Squamata: Elapidae)

Little is known about spermatid development during spermiogenesis in snakes, as there is only one complete study in ophidians, which details the spermatid ultrastructure within the viperid, Agkistrodon piscivorus. Thus, the following study will add to our understanding of the ontogenic steps of spermiogenesis in snakes by examining spermatid maturation in the elapid, Pelamis platurus, which were collected in Costa Rica in 2009. The spermatids of P. platurus share many similar ultrastructural characteristics to that described for other squamates during spermiogenesis. Three notable differences between the spermatids of P. platurus and those of other snakes is a round and shorter epinuclear lucent zone, enlarged caudal nuclear shoulders, and more prominent 3 and 8 peripheral fibers in the principal and endpieces. Also, the midpiece is much longer in P. platurus and is similar to that reported for all snakes studied to date. Other features of chromatin condensation and morphology of the acrosome complex are similar to what has been observed in A. piscivorus and other squamates. Though the spermatids in P. platurus appear to be quite similar to other snakes and lizards studied to date, some differences in subcellular details are still observed. Analysis of developing spermatids in P. platurus and other snakes could reveals morphologically conserved traits between different species along with subtle changes that could help determine phylogenetic relationships once a suitable number of species have been examined for ophidians and other squamates.

Skin of the Red Eye Tree Frog Agalychnis Callidryas (Hylidae, Phyllomedusinae) Contains Lipid Glands of the Type Described in the Genus Phyllomedusa

Several anuran species of the genus Phyllomedusa are known to possess specialized cutaneous glands producing lipids and exhibit a peculiar wiping behavior. This behavior is a stereotyped repertory of fore and hind limb movements distributing hydrophobic molecules onto the body surface and reducing evaporative water loss. No reports are presently available on the occurrence of lipid glands in other phyllomedusine genera, and data on the structure of the secretory units specialized for the production of cutaneous lipids are still unclear. The present report is aimed to answer both questions: it describes lipid glands of the Phyllomedusa type in Agalychnis callidryas and provides light and transmission electron microscope evidence of the syncytial structure of their secretory units, a typical feature of serous glands in anuran skin. This morphological trait supports the hypothesis that lipid glands are a specialized subset of the anuran serous glands, and underlines their flexible role in the skin adaption to sub-aerial environments. Anat Rec, 300:503-506, 2017. © 2016 Wiley Periodicals, Inc.

Phylogeny of Mental Glands, Revisited

Mental glands and their associated delivery behaviors during courtship are unique to the plethodontid salamanders. Because previous interpretations of the evolution of these features were conducted using older phylogenetic hypotheses, we reanalyzed these traits with newer courtship descriptions and contemporary phylogenetic methods. Using Bayesian ancestral state reconstruction methods that have been developed since the first phylogenetic analyses were conducted in the mid-1990s, we reconstructed mental gland and courtship behavior evolution on a Bayesian phylogeny of the nuclear gene Rag1. The most probable ancestral condition for plethodontids was resolved as presence of a mental gland. Loss of a mental gland occurred in each subfamily and was recovered as the most probable ancestral condition for the Spelerpinae. In contrast, parsimony reconstruction recovered the presence of a mental gland in the ancestor to Spelerpinae with multiple secondary losses. We hypothesize that that absence of a mental gland is possibly ancestral in some clades (i.e., Spelerpinae) and secondary in others (e.g., paedomorphic Eurycea). The most probable ancestral form of the mental gland is likely to be the large pad-type distributed extensively in Plethodontinae and Bolitoglossinae. Desmognathans have the most unique mental glands, occurring in an anterior protrusion or bifurcated form (in Desmognathus wrighti). Fan-shaped mental glands evolved independently in Eurycea and Oedipina. Small pads arose independently in Bolitoglossinae, Plethodontinae, and Spelerpinae. Head-rubbing behavior for mental gland delivery mode was recovered as the most probable and parsimonious ancestral state for the Plethodontidae, with independent losses of this behavior in Plethodontinae and Spelerpinae. Because head-rubbing was observed in outgroups, we hypothesize that head-rubbing behavior predated mental gland evolution. Pulling, snapping, slapping, and biting behaviors evolved independently in the Plethodontinae and Spelerpinae and are not homologous with head-rubbing. All hypotheses of mental gland and courtship evolution invoke homoplasy.

Spermatogenic cycle of a plethodontid salamander, Eurycea longicauda (Amphibia, Urodela)

Previous investigators have described the spermatogenic cycles of numerous species of plethodontid salamanders. Most studies describe a fairly stereotypical cycle with meiotic divisions of spermatogenesis commencing in the spring/summer. However, many studies lack details obtainable from histological examination and/or testicular squashes and, instead, provide only mensural data from the testes. Studies that lacked microscopic evaluation often revealed spermatogenic cycles that varied greatly from that of the stereotypical cycle with meiotic divisions commencing in the fall/winter. Those studies hamper comparisons between the spermatogenic cycles of different species and their environments, as they do not provide a correlation between testicular size and any aspect of the spermatogenic cycle. In the following manuscript, we elucidate the spermatogenic cycle of Eurycea longicauda longicauda in an effort to outline an appropriate protocol for analyzing spermatogenesis in salamanders that will facilitate future comparative studies. Like many Nearctic plethodontids, E. l. longicauda exhibits a meiotic wave that travels through the testes during the summer; this process is followed by spermiogenesis, spermiation, and recrudescence in the fall, winter, and spring.

Agkistrodon piscivorus spermatogenesis addendum: The effect of Hurricane Katrina on spermatogenesis of the western cottonmouth snake

Recent studies detailed the spermatogenic cycle of the Western Cottonmouth Snake, Agkistrodon piscivorus and noted that spermatogenesis is bimodal, with active periods during March-June and August-October in southeastern Louisiana. However, only spermatogonia were present in September in the only specimen that was captured and the authors state that the individual "should have a high testis volume and also show spermiogenic activity." The specimen in their study was caught immediately following Hurricane Katrina outside of its normal habitat. Therefore, in order to verify their assumption, individuals were captured during September of 2008 and the testes were spermatogenically active with spermatogonia, spermatocytes, and mature spermatozoa being present in the seminiferous epithelium of the testes. These data indicate that Hurricane Katrina could have had an impact on the spermatogenic cycle in Cottonmouths, resulting in stress-induced testicular regression.

Observations on variation in the ultrastructure of the proximal testicular ducts of the Ground Skink, Scincella lateralis (Reptilia: Squamata)

The North American Ground Skink, Scincella lateralis, is a member of the most speciose family of lizards, the Scincidae. The only descriptions of the testicular ducts of skinks concern the light microscopy of 13 species in eight other genera. We combine histological observations with results from transmission electron microscopy on a sample of skinks collected throughout the active season. The single rete testis has squamous epithelium with a large, indented nucleus and no junctional complexes between cells or conspicuous organelles. Nuclei of sperm in the rete testis area are associated with cytoplasmic bodies that are lost in the ductuli efferentes. The ductuli efferentes have both ciliated and nonciliated cells and show little seasonal variation except for the narrowing of intercellular canaliculi when sperm are absent. When the ductus epididymis contains sperm, the anterior one-third lacks copious secretory material around luminal sperm, whereas in the posterior two-thirds sperm are embedded in a dense matrix of secretory material. Light and dark principal cells exist and both contain saccular, often distended rough endoplasmic reticula, and widened intercellular canaliculi that bridge intracellular spaces. Junctional complexes are lacking between principal cells except for apical tight junctions. Electron-dense secretory granules coalesce at the luminal border for apocrine release. The cranial end of the ductus deferens is similar in cytology to the posterior ductus epididymis. Each of the nine squamates in which the proximal testicular ducts have been studied with electron microscopy has some unique characters, but no synapomorphies for squamates as a group are recognized.

The testicular sperm ducts and genital kidney of male Ambystoma maculatum (Amphibia, Urodela, Ambystomatidae)

The ducts associated with sperm transport from the testicular lobules to the Wolffian ducts in Ambystoma maculatum were examined with transmission electron microscopy. Based on the ultrastructure and historical precedence, new terminology for this network of ducts is proposed that better represents primary hypotheses of homology. Furthermore, the terminology proposed better characterizes the distinct regions of the sperm transport ducts in salamanders based on anatomy and should, therefore, lead to more accurate comparisons in the future. While developing the above ontology, we also tested the hypothesis that nephrons from the genital kidney are modified from those of the pelvic kidney due to the fact that the former nephrons function in sperm transport. Our ultrastructural analysis of the genital kidney supports this hypothesis, as the basal plasma membrane of distinct functional regions of the nephron (proximal convoluted tubule, distal convoluted tubule, and collecting tubule) appear less folded (indicating decreased surface area and reduced reabsorption efficiency) and the proximal convoluted tubule possesses ciliated epithelial cells along its entire length. Furthermore, visible luminal filtrate is absent from the nephrons of the genital kidney throughout their entire length. Thus, it appears that the nephrons of the genital kidney have reduced reabsorptive capacity and ciliated cells of the proximal convoluted tubule may increase the movement of immature sperm through the sperm transport ducts or aid in the mixing of seminal fluids within the ducts.

Ultrastructural description of spermiogenesis within the Mediterranean Gecko, Hemidactylus turcicus (Squamata: Gekkonidae)

We studied spermiogenesis in the Mediterranean Gecko, Hemidactylus turcicus, at the electron microscope level and compared to what is known within other Lepidosaurs. In H. turcicus germ cells are connected via cytoplasmic bridges where organelle and cytoplasm sharing is observed. The acrosome develops from merging transport vesicles that arise from the Golgi and subsequently partition into an acrosomal cap containing an acrosomal cortex, acrosomal medulla, perforatorium, and subacrosomal cone. Condensation of DNA occurs in a spiral fashion and elongation is aided by microtubules of the manchette. A nuclear rostrum extends into the subacrosomal cone and is capped by an epinuclear lucent zone. Mitochondria and rough endoplasmic reticulum migrate to the posterior portion of the developing germ cell during the cytoplasmic shift and the flagellum elongates. Mitochondria surround the midpiece as the anlage of the annulus forms. The fibrous sheath begins at mitochondrial tier 3 and continues into the principal piece. Peripheral fibers associated with microtubule doublets 3 and 8 are grossly enlarged. During the final stages of germ cell development spermatids are wrapped with a series of Sertoli cell processes, which exhibit ectoplasmic specializations and differing cytoplasmic consistencies. The results observed here corroborate previous studies, which show the conservative nature of sperm morphology. However, ultrastructural character combinations specific to sperm and spermiogenesis seem to differ among taxa. Further studies into sperm morphology are needed in order to judge the relevance of the ontogenic changes recorded here and to determine their role in future studies on amniote evolution.

Ultrastructure of spermiogenesis in the Cottonmouth, Agkistrodon piscivorus (Squamata: Viperidae: Crotalinae)

To date multiple studies exist that examine the morphology of spermatozoa. However, there are limited numbers of data detailing the ontogenic characters of spermiogenesis within squamates. Testicular tissues were collected from Cottonmouths (Agkistrodon piscivorus) and tissues from spermiogenically active months were analyzed ultrastructurally to detail the cellular changes that occur during spermiogenesis. The major events of spermiogenesis (acrosome formation, nuclear elongation/DNA condensation, and flagellar development) resemble that of other squamates; however, specific ultrastructural differences can be observed between Cottonmouths and other squamates studied to date. During acrosome formation vesicles from the Golgi apparatus fuse at the apical surface of the nuclear membrane prior to making nuclear contact. At this stage, the acrosome granule can be observed in a centralized location within the vesicle. As elongation commences the acrosome complex becomes highly compartmentalized and migrates laterally along the nucleus. Parallel and circum-cylindrical microtubules (components of the manchette) are observed with parallel microtubules outnumbering the circum-cylindrical microtubules. Flagella, displaying the conserved 9 + 2 microtubule arrangement, sit in nuclear fossae that have electron lucent shoulders juxtaposed on either side of the spermatids basal plates. This study aims to provide developmental characters for squamates in the subfamily Crotalinae, family Viperidae, which may be useful for histopathological studies on spermatogenesis in semi-aquatic species exposed to pesticides. Furthermore, these data in the near future may provide morphological characters for spermiogenesis that can be added to morphological data matrices that may be used in phylogenetic analyses.

Annual dynamics of sperm production and storage in the Mediterranean Gecko, Hemidactylus turcicus, in the southeastern United States

Abstract

The Mediterranean Gecko, Hemidactylus turcicus, is an invasive species found in warmer regions throughout the world, including the southern United States. In Louisiana, H. turcicus appears to be free of competition and has been rapidly expanding its range in the past several decades. However, in Florida and Texas, H. turcicus is heavily out-competed by closely related competitors that do not occur in Louisiana, including H. frenatus, of which a substantial amount of reproductive morphology and ecology is known. Although the reproductive cycle of H. turcicus has been studied in Florida and Louisiana, little is known about the seasonal variation of their oviduct and if they are capable of storing sperm, which can have substantial implications for reproductive competition. We analysed sperm production, storage and seasonal variation in the testes and oviducts of H. turcicus using light and electron microscopy. Previous studies found that female H. frenatus store sperm in the uterine-infundibular region for up to 36 weeks, and that their oviducts are active year-round. In H. turcicus, we found that sperm are stored in the uterine-infundibular region of the oviduct, and sperm are stored from May through August. Hemidactylus turcicus has one breeding season per year, producing three to four clutches between May and August, but between September and February minimal activity occurs in the oviduct. Additionally, male H. turcicus are producing sperm throughout the entire reproductive season, but whether females utilize stored sperm to fertilize eggs or if they mate continually throughout the spring and summer is unknown.

Ultrastructural examination of spermiogenesis within the testis of the ground skink,Scincella laterale (Squamata, Sauria, Scincidae)

Although the events of spermiogenesis are commonly studied in amniotes, the amount of research available for lizards (Sauria) is lacking. Many studies have described the morphological characteristics of mature spermatozoa in lizards, but few detail the ultrastructural changes that occur during spermiogenesis. The purpose of this study was to gain a better understanding of the subcellular events of spermiogenesis within the temperate ground skink (Scincella laterale). The morphological data presented here represent the first complete ultrastructural study of spermiogenesis within the Scincidae clade. Samples of testes from 20 specimens were prepared using standard techniques for transmission electron microscopy. Many of the ultrastructural changes occurring during spermiogenesis within the ground skink are similar to that of other saurians. However, there were a few unique characteristics that to date have not been described during spermiogenesis in other lizards. For example, during early round spermatid development within the ground skink testis, proacrosomal granules begin to form within the acrosomal vesicle before making contact with the apex of the nucleus. Also, a prominent microtubular manchette develops during spermiogenesis; however, the circular component of the manchete is absent in this species of skink. This developmental difference in manchette formation may lead to the more robust and straight mature spermatozoa that are common within the Scincidae family. These anatomical character differences may be valuable nontraditional sources that along with more traditional sources (i.e., mitochondrial DNA) may help elucidate phylogenetic relationships, which are historically considered controversial at best, among species within Scincidae and Sauria.

Ultrastructure of the annual cycle of female sperm storage in spermathecae of the torrent salamander, Rhyacotriton variegatus (Amphibia: Rhyacotritonidae)

This study is the first report on the ultrastructure of the sperm storage glands (spermathecae) in the salamander Rhyacotriton variegatus. The population studied is associated with cold-water, rocky streams of the redwood (Sequoia) zone in northern California. Males possess sperm in their vasa deferentia and undergo spermiation throughout the year, but mating is seasonal. Most females with large, vitellogenic follicles (2.0-3.9 mm mean dia.) collected from February-June contain sperm in their spermathecae, although some females with large follicles lack sperm. Other mature-size females collected during this period have small ovarian follicles (0.9-1.2 mm mean dia.) and lack stored sperm. All females collected from September-November have small follicles (0.6-1.6 mm mean dia.) and lack sperm, except in one instance in which a female collected in November had a small amount of degraded sperm, apparently retained from the previous breeding season. The spermathecae consist of simple tubulo-alveolar glands in which the neck tubules produce a mucoid secretory product, and the distal bulbs, where sperm are stored, contain secretory vacuoles of uniform density that stain positively for glycosaminoglycans. In specimens containing sperm, some bulbs have abundant sperm and others lack sperm, but the ultrastructure is similar in both conditions. The acini contain columnar epithelial cells with wide intercellular canaliculi, and a merocrine process releases the secretion. Spermiophagy occurs. In specimens from spring and summer with small ovarian follicles, the neck tubules are similar to those of breeding females, but the distal bulbs are reduced to cords of cells lacking a discernible lumen. Secretory activity in the distal bulbs is initiated in the fall. Spermathecae of R. variegatus are most similar to those of a stream-dwelling plethodontid, Eurycea cirrigera.

Renal sexual segment of the ground skink,Scincella laterale (Reptilia, Squamata, Scincidae)

Mature squamates possess hypertrophied regions of the distal urinary ducts, the renal sexual segment (RSS). The RSS is believed to provide seminal fluid that mixes with sperm and is released into the female cloaca during coitus. This study is the first to describe ultrastructure of the RSS in a lizard collected throughout the active season. The species examined, Scincella laterale, represents the largest family (Scincidae: 1,200 species) of lizards. Although sperm are present in the posterior ductus deferens of male S. laterale throughout the year, an annual spermatogenic cycle occurs that results in spermiation in spring, coinciding with maximum development of the RSS. Female S. laterale may possess stored sperm in vaginal crypts from March-May and large oviductal eggs April-June. Thus, the correlation between mating and RSS activity observed in other squamates is also found in S. laterale. Cytologically, the active RSS consists of columnar cells with numerous apical, electron-dense secretory vacuoles which are released by an apocrine process. The granules stain positively for proteins with bromphenol blue and react with PAS for neutral carbohydrates. After the mating season the RSS undergoes recrudescence and the electron-dense granules are replaced by a mucoid secretion that characterizes more proximal portions of the nephric tubules throughout the year. Little variation in ultrastructure of the RSS occurs between S. laterale and Cnemidophorus lemniscatus (Teiidae), the only other lizard in which seasonal variation of the RSS has been studied using similar methods. Females exhibit differentiation similar to that of males in the distal urinary tubules, but to a lesser degree. This is only the second such report for female squamates, and the differentiation of the region in females is proposed to result from adrenal androgens.

Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). IV. Occurrence of an ampulla ductus deferentis

The distal end of the ductus deferens of Seminatrix pygaea (Cope) differs from more proximal portions of the tube by possessing a highly fluctuated epithelium. Similar morphology has been reported in this area in one lizard and some mammals and the region has been designated in these taxa as the ampulla ductus deferentis. In this study, light and transmission electron microscopy were used to study the posterior ductus deferens in S. pygaea and compare the histology in this region to more proximal regions of the duct and to descriptions of the ampulla of other species. Seminatrix pygaea stores sperm throughout the ductus deferens during the entire year. The epithelium of the ductus deferens is not secretory, but the presence of numerous small apical vesicles indicates a role in fluid absorption. In addition to the highly folded epithelium, clusters of sperm nuclei are more intimately associated with the apical ampullary epithelium than elsewhere in the ductus deferens. No evidence of phagocytosis of sperm was found. In contrast, the ampulla of mammals and presumably the lizard Calotes versicolor is glandular and phagocytic. The common character shared by the squamates and mammals with specializations in this area is the folded epithelium, and whether this is due to shared ancestry with amniotes or is homoplastic is unresolved.

Oviductal sperm storage in the ground skinkScincella laterale holbrook (Reptilia: Scincidae)

The reproductive tracts of female ground skinks, Scincella laterale, collected at various times throughout their reproductive cycle were examined by light and transmission electron microscopy. Examination of the tracts revealed that sperm are retained in the posterior vagina after mating but prior to the ovulation of oocytes. The sperm are not sequestered in specialized glands but occur in scattered clusters in the lumen or among the deep, narrow rugae. The simple columnar lining of the vagina consists mostly of ciliated cells interspersed with occasional secretory cells. After ovulation, as indicated by the presence of eggs in the uterus, sperm are not found in the vagina. No sperm or sperm storage tubules occur in the infundibulum, the characteristic location for sperm storage in scleroglossid squamates that have been studied. Our results are a further indication that too few species have been examined to construct a rigorous phylogenetic hypothesis about the occurrence of sperm storage tubules in lizards.

Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). III. Sexual segment of the male kidney

In mature male snakes and lizards, a distal portion of the nephron is hypertrophied in relation to its appearance in females and immature males. This sexual segment of the male kidney apparently provides seminal fluid that is mixed with sperm and released into the female cloaca during copulation. In this article, we provide the first study at the ultrastructural level of seasonal variation in the sexual segment of the kidney of a squamate, the natricine snake Seminatrix pygaea. Previous workers have indicated that the sexual segment is secretory only when the testes are spermatogenically active. The sexual segment of the kidney in S. pygaea does not go through an extended period of inactivity but does show a cycle of synthesis and secretion that can be related to the spermatogenic cycle and mating activity. We show that synthesis of secretory product is initiated with the onset of spermatogenic activity in the spring and culminates with completion of spermiation in the fall. Secretion of the product, however, occurs in a premating period in March when the testes are inactive. Secretion during this premating period is probably necessary to provide time for the passage of the products down the ureter in order to mix with sperm during mating later in spring.

Uterine epithelial-sperm interaction, endometrial cycle and sperm storage in the terminal zone of the oviducal gland in the placental smoothhound, Mustelus canis

The fate of spermatozoa deposited within the female reproductive tract has been described in the smoothhound, Mustelus canis. Evidence of uterine epithelial-sperm interaction is presented, as well as documentation of sperm storage specifically in the terminal zone of the oviducal gland. Sperm fate is correlated with morphology of the endometrial cycle and specificity of storage in the oviducal gland. The endometrium of M. canis undergoes dramatic tissue remodeling associated with gestation. In females harboring fertilized ova or preimplantation yolk-reliant embryos, the uterine epithelium is simple cuboidal with mucous droplets for lubrication. The presence of the embryo elicits a response from the uterus, which becomes modified for nutrient and respiratory exchange into vascular uterine attachment sites that abut the distal aspect of the yolk sac. Areas of the uterus adjacent to the uterine attachment sites are termed paraplacental sites. Uterine attachment sites are simple squamous while the paraplacental epithelium is simple columnar. Paraplacental cells have basal metachromatic vesicles and a dense array of apical cytoplasmic filaments. Immediately postpartum the uterine attachment sites, now termed uterine or placental scars, begin to remodel to a mucous epithelium for the next gestational cycle. Paraplacental cells slough off the apical filamentous portion, and sperm become embedded in the epithelium. Bundled sperm occur throughout gestation in the terminal zone of the oviducal gland. Sperm are not embedded in the terminal zone epithelium as in the uterus. Following sperm release from the uterus, the paraplacental epithelium reverts to a mucous epithelium for the next reproductive cycle. Fertilization is presumed to occur in the anterior oviduct above the oviducal gland. The physiological mechanisms that mediate sperm-uterus attachment, release, and storage in the terminal zone of the oviducal gland are currently under investigation.

Female sperm storage in amphibians

The three orders of extant amphibians are Gymnophiona, Anura, and Urodela. Although all gymnophionans apparently have internal fertilization and many are viviparous, female sperm storage is unknown. Internal fertilization has convergently evolved in a few anurans, but females of just one species, Ascaphus truei, are known to possess oviductal sperm storage tubules (SSTs). The SSTs of A. truei are similar anatomically to such glands in squamate reptiles. This similarity is convergence due to similar functional adaptations and/or internal design constraints. In salamanders and newts (Urodela), absence of sperm storage in females is the ancestral condition (three families). In the derived condition, sperm storage occurs in cloacal glands called spermathecae, and their possession is a synapomorphy for females in the suborder Salamandroidea (seven families). Salamandroids are the only vertebrates with cloacal sperm storage glands. In this paper, a phenetic analysis of variation in spermathecal characters reveals patterns of convergence in certain spermathecal characters in unrelated taxa that breed in similar habitats. In the family Salamandridae, a role in sperm nutrition for the spermathecal epithelium is questioned, and the widespread occurrence of spermiophagy is related to other reproductive strategies. I propose how the packaging of sperm in structurally different types of spermathecae may influence male paternity.