New publication: habitat influences Spotted Salamander stress hormones

Spotted Salamanders (Ambystoma maculatum) require vernal pools for breeding habitat. Limited protection and preservation of vernal pools makes suitable habitat creation important. Differences in corticosterone levels, a hormone associated with growth, development, and stress in amphibians, could indicate population health and habitat quality. Our objective was to determine if habitat characteristics in created vernal pools influence corticosterone levels of Spotted Salamander larvae. In May and June of 2015 and 2016, we sampled water-borne corticosterone levels of larval Spotted Salamanders in 34 created vernal pools constructed 1–5 years earlier. Using multiple regression, we determined the best model predicting corticosterone levels included larval total length, pool-water temperature, year sampled, and pool diameter. Pool-water pH, depth, and age; percent cover; and predator presence were not significant predictors. Annual variation in corticosterone levels and habitat characteristics, and positive associations with water temperature and salamander body size highlighted the importance of controlling for external influences. The negative association between pool diameter and corticosterone indicated that larvae in larger pools (up to 12.75-m maximum diameter) were less stressed and potentially healthier. These results indicate that pool diameter contributes to habitat quality and may be important when constructing vernal pools for Spotted Salamanders.

Millikin AR, Woodley SK, Davis DR, Anderson JT. 2019. Habitat characteristics in created vernal pools impact spotted salamander water-borne corticosterone levels. Wetlands 39:803–814. [PDF]


New publications: two new records for Texas

Two new, noteworthy records for Texas were published in the March 2019 issue of Herpetological Review. The first was a western range extension of the Lesser Siren, Siren intermedia (though there is some taxonomic confusion surrounding this species identification), from the Rio Grande watershed in Kinney County. The second represents a new species of reptile for the state of Texas. I collected several specimens of Sri Lankan House Geckos (Hemidactylus aff. parvimaculatus) in east Texas. This species has not been previously reported from Texas and appears to expanding its range along the I-10 corridor from New Orleans and suspect that it will continue to be discovered in new localities.

Davis DR, Ruppert KM, Kline RJ. 2019. Geographic distribution: Siren intermedia (Lesser Siren). Herpetological Review 50:95–96. [PDF]

Davis DR, LaDuc TJ. 2019. Geographic distribution: Hemidactylus aff. parvimaculatus (Sri Lankan House Gecko). Herpetological Review 50:102. [PDF]

New publication: effects of glyphosate and captivity on bacterial microbiota in False Map Turtles

Understanding how environmental factors influence various aspects of freshwater turtle health remains an important yet understudied topic within the context of individual–environment interactions. This is particularly true of hostassociated bacterial microbiota, which are being increasingly recognized as a significant and understudied topic in the context of individual turtle health. While this area of work has expanded in certain areas, research efforts remain limited with regard to host–microbiota interactions in the context of habitat contaminants. Specifically, the commonly used herbicide, glyphosate, is of interest due to its massive worldwide use and known effects on various organisms. Effects of captivity on host-associated microbial community structure also remain largely unknown in various nonmodel organisms. To address these unknown effects of Roundup® and captivity on host-associated microbiomes, we examined the effects of low-level Roundup® exposure and captivity on the cloacal microbiota of the False Map Turtle, Graptemys pseudogeographica. We determined the effect of glyphosate by taking cloacal swabs pre- (0 h) and postexposure (72 h) and examined microbial community beta- and alpha-diversity through 16S rRNA gene high-throughput sequencing. The results of this study indicate that low-level, short-term glyphosate exposure does not significantly alter the microbiota structure of G. pseudogeographica. However, there was a significant decrease in microbial community beta-diversity over time, confirming a trend that has been observed to a limited extent in other non-model organisms when put in laboratory conditions. These results are useful in understanding the baseline cloaca microbial community structure of G. pseudogeographica, as well as the implications and limitations of laboratory-based microbiota studies. Furthermore, this work suggests that low-level and short-term glyphosate exposure does not have a significant effect on the cloacal microbial community structure in wild-caught G. pseudogeographica.

Madison JD, Austin SD*, Davis DR, Kerby JL. 2018. Bacterial microbiota response in Graptemys pseudogeographica to captivity and Roundup® exposure. Copeia 106:580–588. [PDF]


New publication: co-infection of Bd and RV in Oklahoma amphibians

Global amphibian decline continues to be a great concern despite our increased understanding of the causes behind the observed patterns of the decline, such as habitat modification and infectious diseases. Although there is a large body of literature on the topic of amphibian infectious diseases, pathogen prevalence and distribution among entire communities of species in many regions remain poorly understood. In addition to these geographic gaps in our understanding, past work has focused largely on individual pathogens, either Batrachochytrium dendrobatidis (Bd) or ranavirus (RV), rather than dual infection rates among host species. We sampled for prevalence and infection load of both pathogens in 514 amphibians across 16 total sites in northeastern Oklahoma. Amphibians were caught by hand, net, or seine; they were swabbed to screen for Bd; and liver tissue samples were collected to screen for RV. Overall results of quantitative PCR assays showed that 7% of screened individuals were infected with RV only, 37% were infected with Bd only, and 9% were infected with both pathogens simultaneously. We also documented disease presence in several rare amphibian species that are currently being  monitored as species of concern due to their small population sizes in Oklahoma. This study synthesizes a growing body of research regarding infectious diseases among amphibian communities in the central United States.

Watters JL, Davis DR, Yuri T, Siler CD. 2018. Concurrent infection of Batrachochytrium dendrobatidis and ranavirus among amphibians from northeastern Oklahoma, USA. Journal of Aquatic Animal Health 30:291–301. [PDF]


New publication: new species of Lygosoma from Indochina

Based on molecular and morphological data sets, we describe a new species of scincid lizard of the genus Lygosoma from Indochina, and redescribe true Lygosoma quadrupes (Linnaeus, 1766). The new species is small and slender, and represents the third member of the L. quadrupes complex, increasing the diversity of Lygosoma species recognized in southeast Asia to 24. Based on the reevaluation of vouchered specimens from the type locality of L. quadrupes sensu Linnaeus (1766), the recognized geographic distribution of true L. quadrupes is restricted to the island of Java in Indonesia. With 10 species of Lygosoma recognized in Thailand, the country possesses considerable species-level diversity of these enigmatic, semifossorial skinks. In addition to being one of the smallest species in the genus, the new species can be distinguished from all congeners by features of its external morphology, including having small relative limb lengths, longer trunk length, and greater numbers of axilla–groin and paravertebral scale rows. Phylogenetic analyses support three divergent lineages corresponding to recognized and newly described members of the L. quadrupes complex. The descriptions underscore the need for continued and comprehensive biodiversity survey work throughout much of Southeast Asia, particularly in Indochina, where scincid diversity remains poorly understood.

Siler CD, Heitz BB*, Davis DR, Freitas ES, Aowphol A, Termprayoon K, Grismer LL. 2018. New supple skink, genus Lygosoma (Reptilia: Squamata: Scincidae), from Indochina and redescription of Lygosoma quadrupes (Linnaeus, 1766). Journal of Herpetology 52:332–347. [PDF]


New publication: C. E. Miller Ranch checklist

We report the occurrence of 50 species of amphibians and reptiles recently collected on C. E. Miller Ranch and the Sierra Vieja in the Chihuahuan Desert of Texas, USA and describe their perceived distribution and abundance across various habitat associations of the region. Our recent surveys follow intense, historic sampling of amphibians and reptiles from this region in 1948. Of the 50 species detected in recent surveys, six were not collected in 1948 and an additional three species documented in 1948 have yet to be detected in a 14-year period of recent surveys. Combining data from both historic and recent surveys, a total of 53 species of amphibians and reptiles are known from the ranch (11 amphibians, 42 reptiles). Land stewardship and conservation practices have likely contributed to the persistence of the majority of these species through time. Additionally, we discuss the status of amphibians and reptiles not collected during recent surveys and comment on potential species that have not yet been detected.

Davis DR, LaDuc TJ. 2018. Amphibians and reptiles of C. E. Miller Ranch and the Sierra Vieja Range, Chihuahuan Desert, Texas, USA. ZooKeys 735:97–130[PDF] [Corrigenda]


New publication: Lake Oahe, South Dakota distributional records

Apalone_spinifera_DRD-4106South Dakota amphibian and reptile distributional records are lacking, especially in the north-central counties in the state. To date, there have been few surveys of amphibians and reptiles from along Lake Oahe, a large reservoir on the Missouri River that was created in 1958 following construction of Oahe Dam. We conducted fieldwork on Lake Oahe in South Dakota in June 2017 and collected 13 new county records of six species of amphibians and reptiles: Woodhouse’s Toad (Anaxyrus woodhousii), Boreal Chorus Frog (Pseudacris maculata), Smooth Softshell (Apalone mutica), Spiny Softshell (Apalone spinifera), Painted Turtle (Chrysemys picta), and Plains Gartersnake (Thamnophis radix)Prior to these records, no vouchered specimens existed from these areas for these species and only anecdotal evidence or unverifiable reports of species occurrence existed. These vouchered specimens are important as they provide the first verifiable records of species occurrence in an area that is under-surveyed and depauperate of records.

Austin SD, Kerby JL, Davis DR. 2017. Distributional records of amphibians and reptiles from Lake Oahe, South Dakota, USA. Herpetological Review 48:817–820. [PDF]


New publication: Chelydra serpentina diet note

A natural history note describing a new prey item of Snapping Turtles (Chelydra serpentina) was published in the March 2017 issue of Herpetological Review. My co-author, Doug Backlund, photographed an adult male Northern Shoveler (Anas clypeata) being attacked by an adult Snapping Turtle on Farm Island, Hughes County, South Dakota. This observation adds to the list of waterfowl that have been reported as prey of Snapping Turtles and provides an account of predation events that are infrequently observed. Descriptions of the natural history of species such as this are critical and add to our understanding of species.

Davis DR, Backlund DC. 2017. Chelydra serpentina (Snapping Turtle). Diet. Herpetological Review 48:174–175[PDF]

New publications: species distribution records in South Dakota and Michigan

Four new publications documenting the distributions of amphibians and reptiles in South Dakota and Michigan were just published in the March 2017 issue of Herpetological Review. Three of these notes are individual distribution records (2 in South Dakota, 1 in Michigan) and one is a series of 26 county records from South Dakota collected during field work in 2015 and 2016. These South Dakota records have been added to the Amphibians and Reptiles of South Dakota website and help fill gaps in the distributions of species across the state. Even though there has been considerably more herpetological research conducted in Michigan than in South Dakota over the past century, many distributional gaps exist for Michigan species, with species underrepresented in natural history collections. This Michigan record (Ambystoma laterale from Mecosta Co.) was collected as part of a recreational road-trip across the state with Jillian Farkas and highlights the need to continue to document species occurrence.

Davis DR, Farkas JK, Johannsen RE, Leonard KM, Kerby JL. 2017. Distributional records of amphibians and reptiles from South Dakota, USA. Herpetological Review 48:133–137. [PDF]

Davis DR, Zimmer MB. 2017. Geographic distribution: USA, South Dakota, Edmunds Co.: Opheodrys vernalis (Smooth Greensnake). Herpetological Review 48:129–130. [PDF]

Farkas JK, Davis DR. 2017. Geographic distribution: USA, South Dakota, Yankton Co.: Apalone spinifera (Spiny Softshell). Herpetological Review 48:122. [PDF]

Farkas JK, Davis DR. 2017. Geographic distribution: USA, Michigan, Mecosta Co.: Ambystoma laterale (Blue-spotted Salamander). Herpetological Review 48:117. [PDF]

New publication: high prevalence of chytrid fungus in southern Oklahoma

Marhanka.etal.2017_Fig1As part of a collaborative effort with the Siler Lab at the University of Oklahoma, I have been involved in efforts to help screen amphibian skin swabs for the pathogenic fungus, Batrachochytrium dendrobatidis (Bd). This manuscript presents the results of pathogen surveys conducted during 2015 in eight counties in southeastern Oklahoma. Overall Bd prevalence was 64.8% and all families swabbed and 15 (of the 18) species of amphibians had individuals that were Bd+. Given the high Bd prevalence and widespread occurrence of Bd across species and sites, this pathogen has the potential to have profound negative impacts on native Oklahoma amphibians.

Marhanka EC*, Watters JL, Huron NA, McMillin SL*, Winfrey CC*, Curtis DJ, Davis DR, Farkas JK, Kerby JL, Siler CD. 2017. Detection of high prevalence of Batrachochytrium dendrobatidis in amphibians from southern Oklahoma, USA. Herpetological Review 48:70–74. [PDF]