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Rediscovery and redescription of the holotype of Crotalus concolor (Midget-faded Rattlesnake)
Abstract
Here, we redescribe the Crotalus concolor holotype
following the 1929 description by Angus M. Woodbury as a guide.
... Museum specimens can provide one way to shore up data deficiencies for conservation like this (Halm et al. 2022). Recurating and using georeferenced information for all the rattlesnake specimens at the Natural History Museum of Utah, coupled with information from other databases like INaturalist, allowed the UDWR to update Crotalus concolor ranking to S3, which means the species is "vulnerable" in Utah. ...
Natural history specimens were collected for diverse reasons, but modern, and likely
future, uses often diverge from why they were collected. For example, specimens are
sometimes integrated into conservation decision-making, where some practitioners
claim that specimens may be necessary or extremely important for conservation in
general. This is an overstatement. To correct this, I engage with the current literature
on specimen collection to show that while specimens have epistemic shortcomings,
they can be useful for conservation projects depending on the questions or values of
scientists and conservation decision-makers. This modest approach acknowledges
that specimens provide a unique information channel while demarcating where and
when values intercede into conservation planning. In light of the specimen’s utility for
future, sometimes unknown, projects, I also make recommendations for modern
specimen collection.
A new species of Oligodon Fitzinger, 1826 is described based on specimens collected from Churah Valley of Himachal Pradesh. The new species is related to O. arnensis based on molecular as well as morphological data, however differs from it in several aspects. The new species shows a pairwise sequence divergence of 6-20% from congeners for mitochondrial cytochrome b gene. Lack of pterygoid and palatine teeth of the new species suggests that the diet may largely comprise of eggs. Discovery of the new species is not surprising, as the Western Himalayas has been poorly explored in terms of its herpetofaunal diversity. Considerable genetic divergence in the sampled sequence suggests Oligodon arnensis is a species complex, likely represents multiple species and a revision of the group would be desirable.
Coluber fasciolatus Shaw, 1802 (today Argyrogena fasciolata auctt.) is the name used for a widespread terrestrial colubrid snake species inhabiting subtropical and tropical dry deciduous/thorn forests of South Asia from Pakistan to India, with unconfirmed records of distribution in Nepal, Bangladesh and Myanmar and a single doubtful record from the northern tip of Sri Lanka.
During the past 200 years, A. fasciolata (common name Banded racer) has been placed in different genera, i.e. Tyria Fitzinger, 1826, Zamenis Wagler, 1830, Coryphodon Duméril, Bibron and Duméril, 1854, and Coluber Linnaeus, 1758 where it primarly remained until the mid 1960s and exceptionally until the year 2011. Three subsequently introduced names, viz. Coluber hebe Daudin, 1803, Coluber curvirostris Cantor, 1839, and Argyrogena rostrata Werner, 1924 were synonymized with C. fasciolatus shortly after its description.
Based on a combination of characters including body pattern, external morphology and osteological differences Wilson (1967) reviewed the taxon fasciolatus Shaw and considered it as generically distinguishable, removed it from the then heterogeneous and undefined collective genus Coluber and assigned it to the resurrected genus Argyrogena Werner, 1924.
Shaw’s (1802) description of C. fasciolatus was based exclusively on the information of Russell’s “Nooni Paragoodoo” published in 1796 in his “Account of Indian Serpents, collected on the coast of Coromandel; […]”. Our analysis of the original data and the depicted type specimen in Russell (1796) revealed that the name fasciolata was initially established for a species distinct from that currently known as the “Banded racer”, and that Russell’s data have been used simultaneously but unwittingly, for more than 150 years, as original source for two valid species from two different genera.
Specimens of Banded racer found in the southeastern part of peninsular India are morphologically and genetically distinct from populations of the rest of the distribution area. These populations from central and southern Tamil Nadu state represent a different species, consequently described as a new species herein. Furthermore, examination of specimens of the Banded racer from different populations across its entire range, including the type specimen of the genus Argyrogena ( A. rostrata Werner), reveals a similarity in morphology with the genus Platyceps Blyth, 1860. This was further supported by molecular data which demonstrates that the genus Argyrogena is nested within Platyceps .
Natural History of the Midget Faded Rattlesnake (Crotalus concolor)
Scientific findings need to be verifiable and grounded in repeatability. With specimen-level research this is in part achieved with the deposition of voucher specimens. These are labeled, curated, data-based specimens that have been deposited in a collection or museum, available for verification of the work and to ensure researchers are calling the same taxa by the same names. Voucher specimens themselves are the subject of research, from the discovery of new species by taxonomists to ecologists documenting historical records of invasive species. Our objective was to quantify the frequency of voucher specimen deposition in biodiversity and community ecology research through a survey of the peer-reviewed literature about arthropods, from 1989 until 2014. Overall rates of voucher deposition were alarmingly low, at under 25%. This rate increased significantly over time, with 35% of papers reporting on vouchers in 2014. Relative to the global mean, entomological research had a significantly higher rate of voucher deposition (46%), whereas researchers studying crustaceans deposited vouchers less than 6% of the time, significantly less than the mean. Researchers working in museums had a significantly higher frequency of voucher deposition. Our results suggest a significant culture shift about the process of vouchering specimens is required. There must be more education and mentoring about voucher specimens within laboratories and across different fields of study. Principal investigators and granting agencies need a proactive approach to ensuring specimen-level data are properly, long-term curated. Editorial boards and journals can also adopt policies to ensure papers are published only if explicit statements about the deposition of voucher specimens is provided. Although the gap is significant, achieving a higher rate of voucher specimen deposition is a worthy goal to ensure all research efforts are preserved for future generations.
The Western Rattlesnake (Crotalus viridis), the most widespread and phenotypically variable rattlesnake in North America, has been partitioned into nine subspecies based on size, color, pattern, scutellation, and geographic distribution. Several subspecies, especially those occurring in the western portion of the range, have proved difficult to identify due to similarities in scutellation, color and pattern ontogeny, and because specimens fade in preservative. Over a half-century has elapsed since Laurence Klauber’s extensive work on the C. viridis group. Since that time, researchers have used a range of phenotypic characters to further elucidate relationships among members of this group, but a comprehensive phylogenetic analysis incorporating a wide range of morphological characters has not been accomplished. Analyses of snake lineages using mitochondrial (mt) DNA genes as molecular markers appear promising in reconstructing relationships, substantiating
previously identified clades, and revealing new ones. Since 1987, three studies using mtDNA gene sequences have partitioned
the C. viridis complex into eastern and western groups, but researchers have been unable to resolve relationships in the latter.
The goal of this study was to evaluate earlier results and to resolve relationships in the western clade by utilizing two rapidly evolving mtDNA genes (ATPase 8 and 6). We sampled from a wide range of populations, emphasizing those from the
Colorado Plateau because it is an area pivotal to understanding the evolution of C. viridis. In this region, six taxa (C. v. abyssus, C. v. cerberus, C. v. concolor, C. v. lutosus, C. v. nuntius, and C. v. viridis) potentially contact one another in the area of the Grand Canyon. The remaining three taxa occur west of the Colorado Plateau. Crotalus v. helleri and C. v. oreganus are found along the Pacific Coast and inland, and C. v. caliginis is restricted to Isla Sur of the Islas de los Coronados off the coast of Baja California Norte.
Our study includes all nine subspecies of the C. viridis complex plus two outgroups (153 individuals, 111 from the Colorado Plateau), and results were derived from 669 base pairs of sequence data. Net percent sequence divergence ranged from 0.4 ± 0.2 (viridis and nuntius) and 1.0 ± 0.3 (abyssus and lutosus), to 7.3 ± 0.9 (lutosus and nuntius). Weighted and unweighted maximum parsimony (MP), maximum likelihood (ML), and distance analyses rooted with Agkistrodon contortrix and Crotalus scutulatus all supported the same clades. Unweighted MP produced 99 equally most-parsimonious trees. A strict consensus, resampled 1,000 times, supported (94%) the monophyly of the C. viridis species group. The eastern clade (C. v. viridis and C. v. nuntius)
was 100% diagnosable, and in this clade C. v. nuntius was resolved at only 52%. Eastern and western clades differed at 6.1 ± 0.9 percent sequence divergence, and thus are on separate evolutionary trajectories. The eastern clade is most appropriately viewed as a distinct species, with C. v. nuntius placed in synonomy with C. viridis. The western clade is also well-defined (87%) and contains five Colorado Plateau lineages: (1) C. v. cerberus (72%), (2) C. v. concolor (92%), (3) a C. v. lutosus and C. v. abyssus clade (92%) that contains abyssus (88%) and a paraphyletic lutosus, (4) a paraphyletic C. v. oreganus, and (5) a C. v. helleri clade (89%) within which C. v. caliginis is nested. Crotalus v. cerberus is the basal-most taxon in our western clade and distinct from the other western clades. Relationships among the other western clades are less robust, suggesting a more-recent evolutionary history. Nonetheless, because these lineages are also well-defined and on separate evolutionary trajectories, we propose the elevation of C. v. abyssus, C. v. cerberus, C. v. concolor, C. v. helleri, C. v. lutosus, and C. v. oreganus to specific status. Furthermore, because C. v. caliginis is nested in C. v. helleri, we propose that this taxon should be placed in synonomy with C. helleri. The two undescribed clades within our western group (lutosus-like, L3; oreganus-like, O1) will require additional sampling and molecular, morphological, and natural historical analyses to clarify their taxonomy (i.e., potential new species)
We infer the phylogeography of the Western Rattlesnake (Crotalus viridis) using phylogenetic analysis of mitochondrial DNA sequences from 1345 bp of the genes for cytochrome b and NADH dehydrogenase subunit 4. Two main clades are revealed: one includes populations from east and south of the Rocky Mountains (conventionally referred to as Crotalus viridis viridis and C. v. nuntius), and the other consists of populations west of the Rocky Mountains. Within the western clade, a population from southern Arizona (C. v. cerberus) represents the sister taxon to the remaining western populations. The conventional subspecies recognized in this species do not fully correspond to the phylogenetic pattern, and a review of the systematic status of several populations is needed. Our data allow the inferences that small body size evolved twice and that the ability of one population (C. v. concolor) to secrete highly lethal toxins related to Mojave toxin arose within the complex. Our phylogeny should represent the basis for further studies on the causes of geographical variation in this complex.
symptoms consistent with biochemical analyses, with numbness associated with the bite, coagulation abnormalities and essentially no tissue damage. Results suggest that the occurrence of potent neurotoxic component(s) in a venom minimizes prediges- tive components (metalloproteases). Further, concurrence of these functional com- ponents in the venom of an individual may be selected against, and highly toxic venom in both juvenile and adult C. o. concolor may represent a form of venom paedomorphosis.
The midget faded rattlesnake (Crotalus viridis concolor) venom: lethal toxicity and individual variability. Toxicon15, 129–133, 1977.—Crotalus viridis concolor venoms were collected from captive specimens from northeastern Utah and tested for lethal potency in mice and for protein content by polyacrylamide gel electrophoresis. We found C. v. concolor potency (i.p.-ld50-0·25 μg per g) comparable to Crotalus durisses terrificus (i.p.-ld50-0·25 μg) and Crotalus scutulatus scutulatus (California variety) (i.p.-ld50-0·24 μg per g) venoms. Individual C. v. concolor venoms show a wide variability both in lethality and protein pattern. The venom appears to be one of the most lethal Crotalid venoms in the New World.
Crotalus viridis, the western rattlesnake, ranges throughout western North America and has been divided into at least eight subspecies. However, the validity of and relationships among these subspecies and the monophyly of C. viridis as a whole are questionable. We used mitochondrial DNA sequence data from the D-loop region and ND2 gene to examine the relationships among 26 populations of C. viridis and to test the monophyly of this species. These data were analyzed separately and combined using maximum-likelihood and maximum-parsimony. The C. viridis group was monophyletic in all combined analyses, consisting of two strongly divergent clades. We recommend that these clades be recognized as two distinct evolutionary species: C. viridis and C. oreganus. Crotalus viridis should be restricted to the subspecies viridis and nuntius and the remaining subspecies be assigned to the species C. oreganus. Our data do not allow strong evaluation of the validity of the subspecies. We found that the ND2 gene had greater sequence divergences among closely related individuals than the D-loop region, but this relationship reversed at higher levels of divergence. This pattern is apparently due to: (1) ND2 third positions evolving faster than the D-loop but becoming saturated at higher levels of divergence, and (2) the D-loop evolving faster than ND2 second (and possibly first) positions. Our results suggest that the ND2 gene is preferable for examining intraspecific relationships and the D-loop may better resolve relationships between species of snakes. The latter result is contrary to the common perception of the phylogenetic utility of the D-loop. Another unusual result is that the 145 bp spacer region, adjacent to the 5' end of the light strand of the D-loop, provides greater phylogenetic resolution than the 1030 bp D-loop.
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