Hemipenial Morphology Research Articles

Morphology of hemipenes and its taxonomic implication in the fused eyelids species of the genus Ablepharus (Squamata: Scincidae)

The representatives of the genus Ablepharus Fitzinger, 1824 have not been studied in detail from a morphological and taxonomic perspective. The morphology of hemipenes of 14 taxa of the fused eyelids species of the genus was studied. Manual eversion and inflation with absolute ethanol was used for preparation of the organs. The results indicate that the Ablepharus hemipenes show little variation in general shape and main structures: all hemipenes are deeply bifurcated, without large external calcified or keratinous spines or similar structures. Based on hemipenial morphology, the studied taxa can be separated into two clades: 1) with long, slender and 2) with short, robust lobes of the hemipenis. The morphology of this structure demonstrates close relationships between the fused eyelids ablepharine skinks, points out unresolved taxonomic problems, and shows general congruence with available molecular phylogenies. Hemipenial characteristics appear to be a useful tool for the identification of the species within the genus. Problems associated with the real taxonomic status of the Ablepharus budaki anatolicus paratypes and the distribution of other taxa are discussed. The morphology of the hemipenis of the family Scincidae and the related, inconsistent use of terminology are also commented on.

Taxonomic re-evaluation of the subspecies of Hebius vibakari (Boie, 1826) (Reptilia: Serpentes: Natricidae), with new evidence from central and northern China

Hebius vibakari (Boie, 1826), the type species of the genus Hebius, currently includes three subspecies: Hebius vibakari vibakari, endemic to Japan except for the Hokkaido region; Hebius vibakari ruthveni (Van Denburgh, 1923), found in the Korean Peninsula, northeastern China, and eastern Russia; and Hebius vibakari danjoensis (Toriba, 1986), native to the Oshima Island, Danjo Islands, Japan. However, the taxonomic status of three subspecies has not been evaluated for many years. Integrating data from previous studies and new records from central and northern China, we evaluated the systematic positions of H. v. vibakari and H. v. ruthveni based on comparative morphology and molecular phylogenetics. Analysis recovered H. vibakari as a monophyletic group, composed of three major clades that could not correspond to the nominative subspecies. As molecular and morphological evidence could not distinguish H. v. ruthveni from H. v. vibakari, we synonymized the junior nomen H. v. ruthveni with H. v. vibakari. A detailed description of Hebius vibakari is provided, including hemipenial morphology, and the taxonomic status of the subspecies H. v. danjoensis is discussed.

Hemipenial morphology does not provide insight on mating barriers between the two main lineages of Hierophis viridiflavus (Lacépède, 1789)

Hemipenial morphology does not provide insight on mating barriers between the two main lineages of Hierophis viridiflavus (Lacépède, 1789)

Hemipenial morphology of whiptail lizards Glaucomastix abaetensis and Glaucomastix littoralis , with comments on the genus Ameivula (Teiidae: Teiinae).

Hemipenes are important structures for the systematics of Squamata, and may assist in the diagnosis of closely related taxa. Only one of the species of Glaucomastix (G. venetacauda) had its hemipenial morphology described in literature so far. Here we analyze and describe for the first time the hemipenes of seven specimens of G. abaetensis and 20 specimens of G. littoralis from the reptile collection of Museu Nacional, Universidade Federal do Rio de Janeiro. In both species the hemipenes are bilobed with a forked sulcus spermaticus in a centripetal orientation and present laminar ornamentations on the hemipenial body and paired awns on the apical region of the lobes. The two species differed from each other only in the modal number of proximal laminae. The main differences in hemipenial morphology between Glaucomastix and its sister genus Ameivula are the presence of laminae in the hemipenial body (absent in Ameivula) and the absence of digitiform papillae on the apical lobular region (present in Ameivula). We expect that our data can be used as an additional tool to diagnose species within the genus Glaucomastix/Ameivula.

A new species of Ninia (Serpentes, Colubridae) from western Ecuador and revalidation of N. schmidti

We describe a new species of Ninia Baird & Girard, 1853 endemic to the cloud forests of northwestern Ecuador. The new species has previously been confused with N. atrata (Hallowell, 1845) and N. teresitae (Angarita-Sierra and Lynch 2017) but is genetically most closely related to a third species of Ninia endemic to the Chocoan–Tumbesian transition area of western Ecuador. We revalidate the name N. schmidti (Jan, 1862), designate a neotype, and provide a diagnosis of the taxon and a description of its hemipenial morphology based on new material. The new and revalidated species can easily be identified from one another and from other trans-Andean South American Ninia based on ventral and subcaudal scale counts, hemipenial morphology, and coloration of the supralabials, throat, and belly. Finally, we remove N. atrata from the herpetofaunal list of Ecuador.

Integrative taxonomy of theIphisa elegansspecies complex (Squamata: Gymnophthalmidae) leads to the description of five new species

AbstractWe reassessed the taxonomic status of lizards of the Iphisa elegans complex, a monotypic genus of Gymnophthalmidae, based on the congruence between mitochondrial DNA (Cytb) and nuclear DNA (c-mos and prlr) and characters of internal and external morphology, both quantitative and qualitative (meristic, morphometric and hemipenial), throughout its wide Amazonian distribution. The congruence of three species delimitation analyses (mPTP, bGMYC and ASAP), nuclear DNA topology and morphological evidence resulted in nine operational taxonomic units in the genus Iphisa. Besides being recovered as monophyletic groups in mitochondrial and nuclear phylogenetic trees, these nine operational taxonomic units can be distinguished by external and hemipenial morphology. Finally, we propose a new taxonomic rearrangement of the genus, whereby we: (i) restrict I. elegans to north-east Amazonia in the Guiana Shield and southwards, west from the Purus–Madeira interfluvium, on the right bank of the Amazon River; (ii) elevate Iphisa elegans soinii Dixon, 1974 to the specific level Iphisa soinii Dixon, 1974 comb. nov.; and (iii) name and describe five new species.

A new species of Dipsas (Serpentes, Dipsadidae) from central Panama.

A new species of Dipsas Laurenti, 1768, from Central Panama is described based on molecular analyses, hemipenial morphology, and external characters. This is the sixth species of Dipsas to be described for the country; the snake has been suspected to exist since 1977 and has not been thoroughly studied until now. Additionally, morphological comparations including scale counts are done with other species within the genus, and the current geographic distribution of Dipsastemporalis (Werner, 1909), the sister species, is updated. Finally, a key to the species of Dipsas currently known from Middle America is presented.

Total-evidence phylogeny and evolutionary morphology of New World pitvipers (Serpentes: Viperidae: Crotalinae).

Crotalines (pitvipers) in the Americas are distributed from southern Canada to southern Argentina, and are represented by 13 genera and 163 species that constitute a monophyletic group. Their phylogenetic relationships have been assessed mostly based on DNA sequences, while morphological data have scarcely been used for phylogenetic inquiry. We present a total-evidence phylogeny of New World pitvipers, the most taxon/character comprehensive phylogeny to date. Our analysis includes all genera, morphological data from external morphology, cranial osteology and hemipenial morphology, and DNA sequences from mitochondrial and nuclear genes. We performed analyses with parsimony as an optimality criterion, using different schemes for character weighting. We evaluated the contribution of the different sources of characters to the phylogeny through analyses of reduced datasets and calculation of weighted homoplasy and retention indexes. We performed a morphological character analysis to identify synapomorphies for the main clades. In terms of biogeography, our results support a single colonization event of the Americas by pitvipers, and a cladogenetic event into a Neotropical clade and a North American/Neotropical clade. The results also shed light on the previously unstable position of some taxa, although they could not sufficiently resolve the position of Bothrops lojanus, which may lead to the paraphyly of either Bothrops or Bothrocophias. The morphological character analyses demonstrated that an important phylogenetic signal is contained in characters related to head scalation, the jaws and the dorsum of the skull, and allowed us to detect morphological convergences in external morphology associated with arboreality.

The taxonomic status of the kukri snake Oligodon arenarius Vassilieva, 2015 with a redescription of Oligodon macrurus (Angel, 1927) (Squamata, Serpentes, Colubridae)

We investigated the taxonomic status of the recently described kukri snakeOligodon arenariusVassilieva, 2015 and the morphologically similarOligodon macrurus(Angel, 1927), two species endemic to the southern coast of Vietnam. Based on phylogenetic analyses using three mitochondrial genes (12S–16S rRNA, cytochromeb), we recoveredO. arenariusandO. macrurusin a clade within theO. cyclurus-taeniatusspecies group, agreeing with previous intrageneric classifications. Genetic distances betweenO. arenariusandO. macrurusare extremely low (less than 0.5% based on 12S–16S) and renderO. arenariusparaphyletic. All preserved specimens ofO. arenariusandO. macrurusconvey little to no differences in color pattern, hemipenial morphology and osteological features; the latter of which is based on three dimensional micro computer tomography (µCT) scans of one specimen per species. Contrasting these results, univariate and multivariate analyses revealed significant differences in relative tail length, and the number of ventral and subcaudal scales between both species. Although the molecular and morphological datasets present conflicting results, integrating the evidence leads us to synonymizeO. arenariuswithO. macrurus. We provide a formal redescription ofO. macrurus, designate a neotype specimen to avoid future taxonomic confusion, and provide the first detailed osteological description of this species.Oligodon macrurussensu stricto is endemic to coastal dunefields and adjacent forest habitats in southern Vietnam, where ongoing human development, tourism and road mortality pose significant threats to its conservation. Consequently, we suggest thatO. macrurusshould be listed as “Vulnerable” based on the assessment criteria of the International Union for Conservation of Nature (IUCN).

A taxonomic re-assessment of Oligodon cinereus (Günther, 1864) (Squamata, Serpentes, Colubridae) populations from southern Indochina

The ashy kukri snake Oligodon cinereus (Günther, 1864) is a widely distributed and morphologically variable species found throughout mainland Southeast Asia. In this paper, we re-assessed the taxonomic status of O. cinereus populations found in southern Indochina (southern Vietnam, Cambodia, and southern Laos), including the recently described Cat Tien kukri snake Oligodon cattienensisVassilieva et al., 2013, which was previously confused with this species. Phylogenetic analyses using mitochondrial DNA from the 12S–16S ribosomal subunit and cytochrome b gene revealed that O. cattienensis is embedded in a mixed clade containing samples of the subspecies O. cinereus pallidocinctus, which bears a dorsal color pattern with white crossbars and black edges. This clade forms a strongly supported sister group with a topotypic sample of O. cinereus cinereus, representing populations bearing a uniform dorsal color pattern and slight reticulate markings, however the genetic divergence between the two clades is very low. The morphological characters used to distinguish O. cattienensis from O. cinereus sensu lato broadly overlap and supposed differences in hemipenial morphology between the two taxa are due to outdated terminologies used to describe the organ. We relegate both O. cattienensis and O. cinereus pallidocinctus to the junior synonymy of O. cinereus and consider all color patterns of this species found near the type locality in Cambodia, southern Laos, and southern Vietnam to represent O. cinereus sensu stricto. Future integrative investigations across the range of O. cinereus sensu lato are needed to resolve the status of the remaining subspecies and synonyms associated with this taxon. Problems associated with hemipenial morphology and Oligodon systematics are also discussed.

Hidden in the highs: Two new species of the enigmatic toadheaded pitvipers of the genus Bothrocophias

Bothrocophias microphthalmus (Cope, 1875) currently comprises most mid- to highland populations of the genus Bothrocophias in the eastern versant of the Andes. We describe two new species of Bothrocophias from the highlands of the Colombian Andes previously referred to as B. microphthalmus based on morphological and genetic evidence. Our phylogenetic analysis revealed that B. micropthalmus as currently recognized is paraphyletic with respect to B. hyoprora, and the two new taxa are sister lineages. These new toadheaded pitvipers can be morphologically distinguished from their congeners based on the presence of contact between the internasal scales, the number of prefoveal scales, the presence of a lacunolabial scale, the arrangement of supralabial scales, ventral scale counts, the color pattern of the dorsal and ventral surfaces of the body and tail, and hemipenial morphology. We discuss some possible taxonomic scenarios for the lineages found within the B. microphthalmus species complex but refrain from making additional taxonomic changes given our reduced sampling of the southern lineages.

New Distribution Site and Supplementary Description on Variations of <i>Gloydius huangi</i> Wang, Ren, Dong, Jiang, Siler et Che, 2019 (Reptilia: Serpentes)

The newly described species Gloydius huangi Wang, Ren, Dong, Jiang, Siler et Che, 2019 were described based on only three specimens from two sites. We report a new distribution site from Markam County, Tibet Autonomous Region, China with supplementary description on variation of morphology and mitochondrial genetics of the species. The new specimen varies from types of G. huangi on head scalation, coloration patterns, and hemipenis morphology. A distinct genetical distance 1.9 – 2.2% based on Cytb gene fragment exist between the new specimen and types of the species.

Pengukuran Awal Hemipenis Sauria Lamprolepis Smaragdina (Scincidae) dan Lophosaurus Dilophus (Agamidae)

The characteristics of the hemipenis Scincidae and Agamidae New Guinea are veryrarely studied, although they are very easy to do. Morphological characteristics andhemipenis size between these two families are very different. Some have a cylindrical hemipenis that is not lobed to lobed, and some even have a variety of structures withdistinctive ornaments. Tail length can affect the length of the hemipenis. This study aims to describe the characteristics of the hemipenis Scincidae and Agamidae New Guinea. The species Lamprolepis smaragdina and Hypsilurus dilophus were sampledto represent other species in these two families. Preservation of lizard hemipenis refersto research by Zaher and Prudente (2003), Dowling and Savage (1960). Comparison of hemipenis morphology of the two species is very different based on the structure and shape. Hemipenis L. smaragdina is cylindrical and not lobed. The surface structure ofthe hemipenis is smooth and there is no distinctive ornament. While H. dilophus has a cylindrical hemipenis not lobulated with a larger size. The structure is rough, wavy and wider. The results of sample measurements in this study have also become strong evidence that the length of the lizard's tail can affect the length of the hemipenis.

On the distribution of Gonyosoma prasinum (Blyth, 1854) and Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang amp; Rao, 2021, with a note on the status of Gonyosoma gramineum Gnther, 1864 (Squamata: Serpentes: Colubridae).

Based on 85 examined specimens, photographs of living specimens and illustrations published in the literature, we refine the distribution ranges of both Gonyosoma prasinum (Blyth, 1854) and of the recently described species Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang Rao, 2021, which was not clearly addressed in its original description. We also redescribe the syntypes of Coluber prasinus Blyth, 1854 and the holotype of Gonyosoma gramineum Gnther, 1864, we discuss the status of this latter taxon, and we describe the hemipenial morphology of G. coeruleum.

First Report of Hemipenial Variation among Some Genera and Species of Shieldtail Snakes (Serpentes: Uropeltidae) from India and Sri Lanka

Hemipenial characteristics have historically provided a wealth of comparative morphological characters for the systematic classification of snakes. However, the organs remain poorly known in many groups, particularly tropical and burrowing lineages. Here, we report on hemipenial morphology for 12 species from five genera from the family Uropeltidae: Melanophidium punctatum, M. cf. wynaudense, Plectrurus perrotetii, Rhinophis karinthandani, R. melanoleucus, R. saffragamus, R. sanguineus, Teretrurus cf. hewstoni, Uropeltis bhupathyi, U. cf. ceylanica, U. macrolepis, and U. rajendrani. Many are photographed or illustrated here for the first time. In Melanophidium, the organ is bulbous and mushroom-shaped, with the sulcus spermaticus winding through numerous convoluted folds. In Plectrurus and Teretrurus, it is simple, smooth, and conical. In Sri Lankan Rhinophis and some Uropeltis, the organ generally resembles previously described hemipenes from other species in those genera in being simple, subcylindrical, and covered in fine spines. However, a median lobular process is observed in the Indian species R. karinthandani, R. melanoleucus, and R. sanguineus, seemingly representing a novel bilobate morphology. One species, U. bhupathyi, exhibits a novel, bulbous morphology, but this may be an artifact of preservation. The hemipenes of the Uropeltidae and their sister group Cylindrophiidae resemble some typhlopoid blindsnakes more than their henophidian relatives such as pythons and boas. Whether this is due to convergence related to microhabitat, a form of sexual selection unrelated to ecomorphology, or symplesiomorphy from an ancestral snake morphology is unclear. Gross hemipenial morphology can now serve to diagnose uropeltids to the genus level or species group, though more data and comparative series are needed to determine whether other characters, such as the number and location of spines, can potentially differentiate taxa at finer scales.

Unveiling an enigma from the Cerrado: taxonomic revision of two sympatric species of Apostolepis Cope, 1862 (Dipsadidae: Xenodontinae: Elapomorphini) from central Brazil

Apostolepis albicollaris and A. cerradoensis are two Elapomorphini snake species, described within a short timespan, from the Cerrado of central Brazil. In their brief descriptions, these two species were diagnosed from congeners largely based on highly variable external morphological characters. Interestingly enough, A. cerradoensis has remained known based on a single specimen since its description. Here, we present a reanalysis of both type specimens, as well as a careful examination of a large series of specimens formerly assigned to these species, based on the comparison of internal and external morphology. We conclude that both species are synonymous, providing evidence for the recognition of A. cerradoensis as a junior synonym of A. albicollaris. Furthermore, an account of its updated diagnosis, morphological variation, geographic distribution, hemipenial morphology, phylogenetic relationships and an osteological description are also provided. We also discuss its conservation status, suggesting that the species is under threat and qualifies to be listed as Vulnerable (VU ab(iii)), considering its rarity, small geographic range, and persistent environmental threats.

Taxonomic Review of the Genus Herpetoreas (Serpentes: Natricidae), with the Description of a New Species from Tibet, China

The taxonomic history of the Amphiesma sensu lato has long been confused, and this complex was recently divided into three genera, i.e., Amphiesma Duméril, Bibron, and Duméril, 1854 sensu stricto, Hebius Thompson, 1913, and Herpetoreas Günther, 1860. Being the least known genus, Herpetoreas is reviewed herein through an integrative taxonomic approach. Our results indicate that specimens previously referred to Hebius parallelus (Boulenger, 1890) from Mêdog, Tibet, China, represent a new species. We describe here this new species and refer it to the genus Herpetoreas; therefore, we remove Hebius parallelus from the Chinese herpetofauna. A diagnostic key to all the species of Herpetoreas is also provided. Furthermore, we re-evaluate the diagnostic characters of the three genera formerly confused with Amphiesma, namely, Amphiesma, Hebius, and Herpetoreas. We provide a key to these three morphologically similar genera. We also emphasize the importance of the maxillary teeth and hemipenial morphology in the generic diagnosis in the family Natricidae.

When the tail shakes the snake: phylogenetic affinities and morphology of Atractus badius (Serpentes: Dipsadidae), reveals some current pitfalls on the snake's genomic age.

Atractus badius has a long and controversial nomenclatural history due to both its antiquity and the brevity of its original description. This species was described based on two syntypes from Java. Later, a lectotype was designated and the distribution range restricted to the Guiana Shield. Although this species has been repeatedly recorded throughout Amazonia and the Andes, these records have been erroneously assigned to A. badius because of a considerable level of confusion in the literature. We found 13 additional specimens of this poorly known snake, expanding our knowledge on its morphological variability, phylogenetic relationships and distribution. In this paper, we report new localities and data on meristic, morphometric, coloration, scales micro-ornamentation, osteology and hemipenial morphology to A. badius. We also determine the phylogenetic position of A. badius as nested in a composite Guiana Shield clade. In addition, we discuss recent advances on the systematics of Atractus and comment on some 'new arrangements' with respect to previously recognized species groups and available morphological evidence. Finally, we highlight the importance of accurate voucher identification before promoting taxonomic changes or implementing nomenclatural acts derived from new phylogenetic hypotheses, and notably propose the synonymy of the recently described A. pyroni with A. roulei.

A new oviparous species of Helicops Wagler, 1828 (Serpentes, Xenodontinae) from Brazilian Amazonia with reflections on the evolution of viviparity among hydropsine watersnakes

We describe a new watersnake species of the genus Helicops from the left bank of the upper Madeira River, southwestern Amazonia, Brazil. Due to its spotted dorsal pattern, it resembles the sympatric species H. hagmanni, H. leopardinus, and H. polylepis, but a combination of features including, scale counts, prominence of dorsal keels, and hemipenial morphology allows its unequivocal recognition. The new species also exhibits oviparous reproduction, representing the fourth egg-laying lineage reported in the genus. The evolution of viviparity among the lineages of Helicops comprises an important debate in the field of the natural history of reptiles, especially regarding the highly unlikely possibilities of reversals from viviparity to oviparity due to constraints of genetic, ecological, and physiological nature. Based on such premises, we reconstructed the reproductive modes within the genus using a preconceived topology and discussed hypothetical scenarios for the emergence of viviparity depending on three possible positions of the new taxon. Finally, we also provide considerations on the apparent restriction of this snake to the left bank of the upper Madeira in the light of classic biogeographic evidence that points to the potential role of this major river as a vicariant element between faunas on its opposite margins.

Systematics of the rare Amazonian genus Eutrachelophis (Serpentes: Dipsadidae), with an emended diagnosis for Eutrachelophis papilio

Integrative analyses of multiple data sources and increased coverage in genetic and taxa sampling have been increasingly clarified the phylogenetic relationships of caenophidian snakes. However, some knowledge gaps remain, especially at higher-levels and among genera, and unclear relationships of some taxa with scant available information. One of these taxa is the recently described Amazonian genus Eutrachelophis (Dipsadidae), whose members are rarely recorded and lack associated molecular information. By analyzing recently collected specimens from Amazonian expeditions, we found a series of Eutrachelophis papilio and obtained molecular information (two mitochondrial genes and one nuclear gene) for two specimens. This allowed the first assessment of the molecular phylogenetic relationships of the genus Eutrachelophis. Molecular phylogenetic trees of the caenophidian diversification were inferred considering the information of 10 genes (five mitochondrial and five nuclear), under both Bayesian and Maximum Likelihood optimality criteria. Resulting trees corroborate the distinctiveness and taxonomic validity of Eutrachelophis, and its family and subfamily level allocation. A highly supported clade composed of Eutrachelophis and another enigmatic Amazonian genus, Arcanumophis, was recovered nested in the subfamily Xenodontinae. The Eutrachelophis + Arcanumophis clade is recovered as sister to a clade containing the remaining genera of tribe Xenodontini. These results do not corroborate that the phenotypic apomorphies of Eutrachelophis are secondarily developed within Xenodontini diversification, therefore refuting the recent allocation of this genus in this tribe. In the light of these results, we reassessed the morphological similarities of Eutrachelophis, Baliodryas and Arcanumophis and their distinctiveness among xenodontines. Based on combined phenotypic and molecular evidence, we propose the revalidation of tribe Eutrachelophiini to better reflect the high evolutionary distinctiveness of these snakes. We also obtained novel data on the morphometrics, meristics, color variations, natural history and geographical distributions from the analyzed museum specimens of Eutrachelophis papilio. We found a considerable variation in the range of analyzed morphological characters, including in some considered as diagnostic, justifying the designation of an emended diagnosis for the species. Despite these advances, some gaps remain with respect to these snakes, such as the taxonomic validity of Eutrachelophis species, molecular phylogenetic relationships of Baliodryas, and the internal and hemipenial morphology of Arcanumophis. Further investigation on these issues and reassessment of museum specimens should increase the knowledge associated with these rare snakes.