Vent Length Research Articles

Sexual Shape Dimorphism in the Stream-Dwelling Salamander Batrachuperus pinchonii (Caudata: Hynobiidae)

Sexual dimorphism is a widespread phenomenon throughout the animal kingdom and has attracted considerable interest in evolutionary biology. Studies on sexual dimorphism in hynobiid salamanders, which exhibit external fertilization and have two different habitat preferences, are limited. In this study, we analyzed sexual size and shape dimorphism of the stream-dwelling salamander Batrachuperus pinchonii based on deposited specimens, which were collected from the same locality with the same sampling date, and then explored if either habitat influences sexual dimorphism. Our results revealed no sexual dimorphism in body size (expressed by snout–vent length); however, other morphometric data indicated a female-biased dimorphism in head length, head width, distance of extremities, chest width, and a male-biased dimorphism in foreleg length, foreleg width, fore palm width, hindleg width, and hind palm width. These results would give some merit for future ecological and functional studies on reproduction in B. pinchonii. That is, female-biased head shape is likely related to ecological selection (e.g., reduction of intersexual food competition) and reproductive investment (e.g., intake of more energy). A female-biased trunk dimorphism may contribute to a fecundity advantage (e.g., increase in reproductive output). Male-biased limb dimorphism may relate to reproduction success. We failed to find dimorphic characteristics related to habitats.

The Amapá treefrog Boana dentei (Bokermann, 1967): diagnosis and redescription (Hylinae: Cophomantini)

ABSTRACT Many aspects of the Amazonian amphibian fauna are yet understudied. This is the case of the Amapá treefrog, Boana dentei, which was described in the 1960s based on a single female specimen from Serra do Navio, a Brazilian region of lowland Amazonian forests in the easternmost portion of the Guiana Shield. The species has been reported only a few times since its description, and phenotypic data from its type locality still remain unknown. We redescribe this treefrog species, including the first characterisation of the male, life colours, tadpole, vocalisation, and notes on habitat, based on a newly collected series from the type locality. Boana dentei is sexually dimorphic with respect to external morphology and colour patterns. Males are distinguished from females by a smaller snout–vent length, lighter dorsal colouration, bright yellow colour in ventral hindlimbs and palm of hand, and enlarged prepollex. Boana dentei is distinguished from other members of the B. albopunctata group by the snout truncate from above and rounded to vertical in profile, calcar absent on heel, black vertical bars on thigh, and vocal repertoire composed of three types of pulsed notes.

Sexual dimorphism in size and shape in the viviparous lizard Abronia taeniata (Squamata: Anguidae) in central Mexico

AbstractIn the present study, we analyse sexual dimorphism in size and shape of morphological attributes in a population of Abronia taeniata in central Mexico. The variables analysed were snout–vent length (SVL), head length (HL), head width (HW), head height (HH), tibia length (TL) and femur length (FL). In the size attributes, males and females had similar SVL, and males were larger in the rest of the variables analysed (HL, HW, HH and FL), except TL. In the case of shape, the females had larger dimensions in the relative logSVL variable, and the males were larger in the relative logHL, relative logHW and relative logHH variables. The variables relative logFL and relative logTL showed no sexual shape dimorphism. The similarity in the sizes and the sexual dimorphism between sexes in attributes of the head and extremities are explained by the hypothesis of sexual selection directed to the structures of the head in males, and in the case of shape in females, to the fecundity hypothesis. Comparative studies that analyse a greater number of morphological variables are necessary to determine the factors that promote the different patterns of sexual dimorphism in the group.

Reproductive Biology and Sexual Dimorphism of Gymnophthalmus vanzoi (Squamata, Gymnophthalmidae) in a Population South of the Amazon River, Brazil

Here, we present data on reproductive biology and sexual dimorphism of a species of Gymnophthalmus (G. vanzoi). We conducted the study in an urban area in the municipality of Santarem, on the campus of the Universidade Federal do Oeste do Para, Para state, Brazil. We collected data from 61 males, 79 females, and 9 individuals of unknown sex. Adults were sampled throughout the year, and juveniles were sampled for nine months. Adult females were larger and heavier than males. We observed sexual dimorphism in snout–vent length, length between limbs, head length, head width, head height, hind limb length, tail width, body mass, and coloration. We recorded reproductive females during 6 months, with the largest secondary follicles observed in June and August, the period of lowest precipitation. Reproductive males were recorded throughout the year, occurring at higher frequencies in December, January, and June–November. Testicular volume did not differ significantly among months (P = 0.0884). We collected the smallest individuals in January, March, July, August, November, and December, which suggests that recruitment occurs throughout the year. Despite the evidence of seasonality in the reproductive cycle with larger follicles and larger volume of testes in the drier season, we suggest that reproduction in G. vanzoi is continuous throughout the year, as we did not find statistical differences in the size of testicles (adjusted for subject body size) among months, and because recruitment occurs across various months of the year.

Diet and Feeding Ecology of Crotalus tzabcan (Serpentes: Viperidae)

The Tzabcan rattlesnake (Crotalus tzabcan) is endemic to the Yucatan Peninsula and is part of the C. durissus complex. Although relatively widespread, it is rather an uncommon species; therefore, little is known about its natural history. Herein, we describe the diet of C. tzabcan on the basis of data from field encounters, museum specimens, and published data. Dietary samples were collected from Campeche, Quintana Roo, and Yucatan, Mexico, and literature records from Belize, representing most of the species' distribution range. Examination of 50 individuals resulted in 28 prey items obtained from 27 snakes. The diet of C. tzabcan consisted exclusively of mammals, including the orders Rodentia (86% of the prey items) and Soricomorpha (7%), and no ontogenetic shift in prey type was detected. However, an ontogenetic telescope is evident, where adults consume larger prey than juveniles but continue feeding on small prey. No sexual dimorphism in snout–vent length and total length was detected in C. tzabcan. No sexual differences in prey mass were found when controlling for snake body length, nor when comparing between sexes in adults and juveniles. The presence of prey was not related to snake collection date, suggesting year-round feeding. There was no difference in prey class and size among snakes from Yucatan dry forest and moist forest. These results suggest a homogenous diet among sexes, seasons, and populations. This is the first detailed study on the diet and feeding ecology of C. tzabcan, and it adds five new prey species: Cryptotys mayensis, Heteromys desmarestianus, H. gaumeri, Oryzomys couesi, and Rattus rattus, as well as two previously reported ones: Mus musculus and Sigmodon toltecus. These findings contrast with anecdotal reports of C. tzabcan consuming reptiles and birds and show many similarities with the related species C. durissus. Additional studies on the natural history of C. tzabcan and related species would help to better understand how the feeding ecology of Neotropical rattlesnakes differs from those species of temperate zones.

Vocal Repertoire and Extreme Sexual Size Dimorphism in the Fijian Ground Frog Cornufer vitianus (Anura, Ceratobatrachidae)1

The vocal repertoire of males of Cornufer vitianus from the lowland mangrove forests of Viwa Island, off the coast of Viti Levu, Fiji is described. All calls were placed into two categories: those with a high fundamental frequency, and those with a low fundamental frequency. Within each category, there is relatively high call variation. Individual males are capable of producing both the low- and high-frequency calls; some males produce predominantly the high-frequency call, others are low-frequency callers, and others alternate between the two forms. C. vitianus is among the most sexually size dimorphic amphibians known. Females were conspicuously and significantly larger than males, and we found the ratio of the mean female-to-male snout–vent lengths of 2.22. Extreme sexual size dimorphism (SSD) is a trait rare among anurans as a whole, yet is most often seen among species of the genera Cornufer and Platymantis of the western Pacific. A hypothesis is put forward relating call variability and SSD in C. vitianus.

The combined effects of temperature and aromatase inhibitor on metamorphosis, growth, locomotion, and sex ratio of tiger frog (Hoplobatrachus rugulosus) tadpoles.

BackgroundThe tiger frog (Hoplobatrachus rugulosus) is widely raised by many farms in southern region of China as an economically edible frog. The growth, development, and sexual differentiation of amphibians are influenced by temperature and steroid hormone level. However, the problem of hormone residues is caused by the addition of exogenous hormones in frog breeding, it is worth considering whether non-sterol aromatase inhibitors can be used instead of hormones.MethodsIn our study, H. rugulosus tadpoles were subjected to two water temperatures (29 °C and 34 °C) and three letrozole concentrations in the feed (0, 0.1 and 1 mg/g) to examine the effects of temperature, aromatase inhibitor and their interaction on metamorphosis, locomotion, and sex ratios. A G-test and contingency table were used to analyze the metamorphosis rate of tadpoles and the survival rate of froglets after feeding for 90 days. A G-test was also used to analyze sex ratios in different treatment groups.ResultsMetamorphosis time and body size (snout–vent length, body mass and condition factor) were significantly different between the two temperature treatments. Metamorphosis time was longer and body size was increased at 29 °C compared to those at 34 °C. Letrozole concentration and the temperature × letrozole interaction did not affect these variables. The jumping distance of froglets following metamorphosis was positively associated with the condition factor; when controlling for condition factor, jumping distance was not affected by temperature, letrozole concentration and their interaction. Temperature and letrozole concentration also did not affect metamorphosis and survival rate. Sex ratio of the control group (0 mg/g letrozole) was 1:1 at 29 °C, but there were more males at 34 °C. The sex ratios of H. rugulosus treated with letrozole at 29 °C and 34 °C were significantly biased toward males, and male ratio increased as letrozole concentration increased. Furthermore, more males were produced at 34 °C than at 29 °C at each letrozole concentration.

Prey Size and Feeding Rate Do Not Influence Trophic Morphology of Juvenile Water Snakes (Nerodia sipedon)

Gape-limited predators, such as snakes, might rely on phenotypic plasticity to cope with variation in prey size, but experimental studies have found mixed evidence for plasticity in snake head morphology. Our study sought to determine whether variation in prey size and feeding rate induce head size plasticity in Northern Water Snakes (Nerodia sipedon). We avoided limitations of previous studies by growing all neonates to a consistent final size (400 mm snout–vent length [SVL]), and uncoupling feeding rate and prey size as potential factors influencing head size through four feeding treatments: big–fast (one large prey item every week), big–slow (one large prey item every other week), small–fast (two small prey items every week), and small–slow (one small prey item every week). Snakes in fast treatments grew faster than snakes in slow treatments, but there were no strong effects of feeding rate or prey size treatments on multiple head size metrics. Females grew faster than males, however, and had longer jaw lengths at 400 mm SVL than did males. Unlike previous studies, our results do not support the presence of phenotypic plasticity in head size in N. sipedon, indicating that head size plasticity in snakes can be species and context specific.

A New Species of Pristimantis (Anura: Strabomantidae) from the Eastern Slope of the Cordillera Oriental, Arauca, Colombia

We describe a new species of Pristimantis from one of the most isolated regions of Colombia, at elevations of 700–800 m in the Tame River basin at the eastern slope of the Cordillera Oriental in Colombia (Department of Arauca). This locality has been in the grasp of guerrilla groups and right-wing paramilitaries, and as a consequence, this region has been historically inaccessible or risky for researchers. The new species is a diurnal forest dweller, similar to Pristimantis savagei and P. vilarsi. It is distinguished from its congeners by having finely shagreened dorsum skin, areolate ventral skin, moderate tympanic membrane size (length = 37.2–58.8% of eye length), long hind limbs (tibia length = 53.6–63.6% of snout–vent length), and an advertisement call composed of a short single note, while lacking ridges on scapula, tubercles on upper eyelid and heel, and basal webbing in toes. In addition to the new species described herein, we demonstrate that subarticular tubercles display more variation than what is commonly described in taxonomic studies of terraranan frogs.

Improving Duct Parameters to Design Auxiliary Ventilation in Mining Roadways Driven

The level of air leakage of air movement through the duct to the face in underground mine is an important factor in ensuring the efficiency of ventilation during mining roadways being driven in mine. Ventilation ducting system leakage can, in many cases, supply an insufficient quantity of air to the workplace.Based on the experimental data of the duct leakage measurement when mining roadways driven in Ha Lam Coal mine, a relationship of leakage coefficient, aerodynamic parameter and geometric parameter of the duct has been derived; also maximum vent length with certain auxiliary ventilation equipments has been determined.

Sexual Dimorphism and Reproductive Characteristics of the Cozumel Spiny Lizard, Sceloporus cozumelae (Squamata: Phrynosomatidae) from Mexico

Abstract: We analyzed sexual dimorphism and reproductive characteristics (minimum size at sexual maturity, clutch size, and reproductive period) of females and males of Sceloporus cozumelae, a species endemic to the Yucatan Peninsula, Mexico, and which belongs to the Sceloporus variabilis group. Sexual dimorphism was recorded, with the males being larger in snout–vent length, head length, head width, forearm length, and tibia length. The average clutch size was 3.4. Females containing eggs and vitellogenic follicles were observed at the same time, indicating that the population produces at least two clutches annually. Minimum size at sexual maturity was similar for both sexes (40 mm), and reproduction, determined according to the months in which gonads were obtained, was synchronous between males and females. The species shows high similarity to populations of S. variabilis in sexual dimorphism and reproductive characteristics; however, it has smaller snout–vent length when compared to other populations of S. variabilis in Mexico.

The effect of post-circumcision mucosal cuff length on premature ejaculation.

We aimed to compare the length of mucosal cuff after circumcision in patients with and without a complaint of premature ejaculation (PE). Sexually active patients without erectile dysfunction that presented to the urology polyclinic between March 2018 and June 2018 were included in this multicentered, prospective study. The circumcision age of the patients, the person who performed the procedure (surgeon, non-surgeon), penile length, and dorsal and ventral penile measurements were recorded and compared between patients with and without PE. A total of 208 patients were included in the study. The mean circumcision age of the patients was 5.7±4.2 years, and the mean dorsal and ventral mucosal sizes were 15.02±4.58 mm and 16.31±4.92 mm, respectively. PE was present in 106 of the participants. There was no statistically significant difference between the PE and non-PE groups in terms of the person who performed the procedure (surgeon, non-surgeon). However, patients with PE had statistically significantly longer dorsal and ventral mucosal measurements compared to those without PE (p<0.001). Our study showed that the dorsal and ventral lengths of mucosal tissue left behind after circumcision are a risk factor for PE. Therefore, special attention should be paid not to leave redundant dorsal and ventral mucosal tissue during this procedure.

Unveiling the roles of interspecific competition and local adaptation in phenotypic differentiation of parapatric frogs.

Understanding how ecological processes affect phenotypic evolution has been and continues to be an important goal of ecology and evolutionary biology. Interspecific competition for resources can be a selective force driving phenotypic differentiation that reduces competition among sympatric species (character divergence), enabling closely-related species to coexist. However, although patterns of character divergence are well documented in both empirical and theoretical researches, how local adaptation to abiotic environment affects trait evolution in the face of interspecific competition is less known. Here, we investigate how patterns in morphological traits of 2 parapatric frog species, Feirana quadranus and F. taihangnica, vary among allopatric and sympatric regions using range-wide data derived from extensive field surveys. Feirana quadranus was overall larger than F. taihangnica in body size (i.e., snout–vent length [SVL]), and the difference between SVL of both species in sympatry was larger than that in allopatry. From allopatry to sympatry, the 2 species diverged in foot and hand traits, but converged in eye size and interorbital span, even when we controlled for the effects of geographic gradients. Sympatric divergence in SVL, hand and foot traits is likely acting as a case of evolutionary shift caused by interspecific competition. In contrast, sympatric convergence of eye-related traits may derive at least partly from adaptation to local environments. These results imply the relative roles of interspecific competition and local adaptation in shaping phenotypic diversification. Our findings illustrate how traits evolve in parapatric species pair due to sympatric divergent and convergent evolution. It thus provides insights into understanding underlying evolutionary processes of parapatric species, that is, competition and local adaptation.

Vertebrae-Based Body Length Estimation in Crocodylians and Its Implication for Sexual Maturity and the Maximum Sizes.

SynopsisBody size is fundamental to the physiology and ecology of organisms. Crocodyliforms are no exception, and several methods have been developed to estimate their absolute body sizes from bone measurements. However, species-specific sizes, such as sexually mature sizes and the maximum sizes were not taken into account due to the challenging maturity assessment of osteological specimens. Here, we provide a vertebrae-based method to estimate absolute and species-specific body lengths in crocodylians. Lengths of cervical to anterior caudal centra were measured and relations between the body lengths (snout–vent and total lengths [TLs]) and lengths of either a single centrum or a series of centra were modeled for extant species. Additionally, states of neurocentral (NC) suture closure were recorded for the maturity assessment. Comparisons of TLs and timings of NC suture closure showed that most extant crocodylians reach sexual maturity before closure of precaudal NC sutures. Centrum lengths (CLs) of the smallest individuals with closed precaudal NC sutures within species were correlated with the species maximum TLs in extant taxa; therefore, the upper or lower limit of the species maximum sizes can be determined from CLs and states of NC suture closure. The application of the current method to noncrocodylian crocodyliforms requires similar numbers of precaudal vertebrae, body proportions, and timings of NC suture closure as compared to extant crocodylians.

Female reproductive cycle of the snaked-eyed Lizard &lt;em&gt;Ophisops elegans&lt;/em&gt; Ménétriés, 1832 (Reptilia: Lacertidae) from Lebanon

We studied the female reproductive cycle of a population of Ophisops elegans lizard from the herpetology collection of the Natural History Museum of the Lebanese University. Females collected during spring and summer showed vitellogenesis in their ovaries with oviposition occurring from May to July followed by a subsequent quiescent period. They produced up to two clutches. Mean clutch size was 3.2 ± 1, range 2-5 eggs. Clutch size was independent of female body size. The smallest female attaining sexual maturity had a snout vent length of 45 mm. Sexual maturity can be attained within one year of age. We found no significant difference in body size between female and male adult lizards. Seasonal variations in the reproductive activity of females were well synchronized with those of males.

&lt;p class="Body"&gt;&lt;strong&gt;New morphological data for &lt;em&gt;Leonseius regularis&lt;/em&gt; (De Leon) (Acari: Phytoseiidae) and a description of a new species of the genus from Brazil&lt;/strong&gt;&lt;/p&gt;

The genus Leonseius Chant &amp; McMurtry (Phytoseiidae: Typhlodrominae) was proposed to accommodate Typhloseiopsis regularis De Leon, 1965, a species with a troubled taxonomic history that was previously classified in the genera Typhlodromus Scheuten, Diadromus Athias-Henriot and Chanteius Wainstein. Due to its Amblyseius-like appearance (long s4, Z4 and Z5, most other setae minute; atypical for a typhlodromine), the poor descriptions of reproductive structures (spermatheca, spermatodactyl), and probably also because at the time it was a monotypic genus, researchers over the years have based the species-level identification of Leonseius regularis mainly on dorsal and ventral idiosomal chaetotaxy and setal length. In a survey of phytoseiid mites conducted in cacao plantations (Theobroma cacao L.: Malvaceae) of the municipality of Ilhéus, Bahia, northeastern Brazil, we identified two distinct morphotypes among specimens initially identified as L. regularis. Herein we provide new morphological data for L. regularis to complement the original description and previous redescriptions, and then describe Leonseius elbanhawyi Carvalho, Ferragut &amp; Oliveira sp. nov., from cacao, distinguishing it from L. regularis by its spermatheca and spermatodactyl. Also, the diagnosis of Leonseius is amended.

Reproduction and sexual dimorphism in the viviparous lizard Sceloporus palaciosi (Squamata: Phrynosomatidae) from the Trans‐Mexican Volcanic Belt, Mexico

AbstractIn this study, sexual dimorphism, reproductive cycles, litter size and offspring size of a population of the little‐known species Sceloporus palaciosi in central Mexico were analysed. Significant male‐biased sexual size dimorphism was recorded in snout–vent length (SVL), head length, head width, forearm length and tibia length. Both sexes showed asynchronous reproductive cycles, and males reached sexual maturity at a smaller SVL (33 mm) than females (37 mm). Testes volumes were small from January to February, testicular recrudescence began from March to June, and decreased in July, but increased again in August and September, followed by a second decrease from October to December. In females, vitellogenesis began from May until ovulation in December. Embryonic development extended from November to March, and a small number of females carried embryos through July. Mean litter size was 4.0 and was positively correlated with female SVL. The length of the reproductive period in S. palaciosi recorded in this study is longer than that recorded for other populations in other parts of this species range. Further studies are needed to clarify reproductive cycles in the other isolated populations of S. palaciosi, and then extended to other species and chromosome races in the Sceloporus grammicus complex.

Genomic pedigree reconstruction identifies predictors of mating and reproductive success in an invasive vertebrate.

The persistence of an invasive species is influenced by its reproductive ecology, and a successful control program must operate on this premise. However, the reproductive ecology of invasive species may be enigmatic due to factors that also limit their management, such as cryptic coloration and behavior. We explored the mating and reproductive ecology of the invasive Brown Treesnake (BTS: Boiga irregularis) by reconstructing a multigenerational genomic pedigree based on 654 single nucleotide polymorphisms for a geographically closed population established in 2004 on Guam (N = 426). The pedigree allowed annual estimates of individual mating and reproductive success to be inferred for snakes in the study population over a 14‐year period. We then employed generalized linear mixed models to gauge how well phenotypic and genomic data could predict sex‐specific annual mating and reproductive success. Average snout–vent length (SVL), average body condition index (BCI), and trappability were significantly related to annual mating success for males, with average SVL also related to annual mating success for females. Male and female annual reproductive success was positively affected by SVL, BCI, and trappability. Surprisingly, the degree to which individuals were inbred had no effect on annual mating or reproductive success. When juxtaposed with current control methods, these results indicate that baited traps, a common interdiction tool, may target fecund BTS in some regards but not others. Our study emphasizes the importance of reproductive ecology as a focus for improving BTS control and promotes genomic pedigree reconstruction for such an endeavor in this invasive species and others.

The Allometry of Sexual Dimorphism in Sceloporus formosus (Squamata: Phrynosomatidae)

In many animal species, adult females and males often differ in characteristics other than primary sexual traits. Thus, body size tends to be related to reproductive success through different pathways in females and males, sex-specific foraging or dispersal strategies, and/or adaptations to reduce intersexual trophic competition. As result of these differences, the body size that conveys maximal fitness often differs between the sexes, favoring the evolution of sexual size dimorphism. In this study, we use an allometric approach to evaluate the changes in magnitude of sexual dimorphism in a population of Sceloporus formosus. Allometry refers to the relationships observed between body size and other organismal traits. Natural and sexual selection on morphological traits may modify allometric relationships. Traits under selection can show positive allometry, with slopes steeper than 1 (hyperallometry). We performed allometric major axis regressions of seven morphological traits on the snout–vent length, a standard measure used as a proxy for lizard size. The major axis regressions of female trunk length and width, and male trunk length showed hyperallometric slopes, suggesting that in S. formosus these traits could be under natural selection.

The roles of sex and morphology in burrowing depth of Iberian spadefoot toads in different biotic and abiotic environments

AbstractHiding behavior is key for most animals’ fitness, but it entails costs that must be balanced with benefits. Most research on this potential trade‐off focuses on hiding time. However, other features that might mirror an actual energy investment on hiding behavior, such as burrowing depth, have long been neglected. In this work, we examined energy‐demanding burrowing behavior of Iberian spadefoot toads (Pelobates cultripes), which hide in burrows they dig with the aid of a hard spade on each hindlimb. Namely, we tested whether toads increased burrowing depth as a response to soil dryness and predator kairomones, in search for subterranean humidity and predator avoidance, respectively. To do so, we measured burrowing depth of adult toads under three different treatments in a repeated‐measures design: damp sand, dry sand and sand with boar predator kairomones. We also checked potential effects of sex and morphology (snout–vent length, body mass, hindlimb length and spade length) on burrowing depth. Morphometric variables measured were not good predictors of burrowing depth: Mainly, body mass showed a negative relationship with burrowing depth. However, despite their greater body mass, females burrowed deeper than males in the damp sand treatment. Albeit, contradicting our hypothesis, males did not respond to the presence of predator kairomones, while females reduced their burrowing depth. This result could be a consequence of predator‐induced stress affecting burrowing ability. Also, both females and males burrowed shallower in the dry‐sand treatment than in the others, which could be due to substrate instability or to dehydration.