The role of Culex territans mosquitoes in the transmission of Batrachochytrium dendrobatidis to amphibian hosts.

BACKGROUND: Mosquitoes are the deadliest organisms in the world, killing an estimated 750,000 people per year due to the pathogens they can transmit. Mosquitoes also pose a major threat to other vertebrate animals. Culex territans is a mosquito species found in temperate zones worldwide that feeds almost exclusively on amphibians and can transmit parasites; however, little is known about its ability to transmit other pathogens, including fungi. Batrachochytrium dendrobatidis (Bd) is a topical pathogenic fungus that spreads through contact. With amphibian populations around the world experiencing mass die-offs and extinctions due to this pathogen, it is critical to study all potential modes of transmission. Because Cx. territans mosquitoes are in contact with their hosts for long periods of time while blood-feeding, we hypothesize that they can transmit and pick up Bd. METHODS: In this study, we first assessed Cx. territans ability to transfer the fungus from an infected surface to a clean one under laboratory conditions. We also conducted a surveillance study of Bd infections in frogs and mosquitoes in the field (Mountain Lake Biological station, VA, USA). In parallel, we determined Cx. territans host preference via blood meal analysis of field caught mosquitoes. RESULTS: We found that this mosquito species can carry the fungus to an uninfected surface, implying that they may have the ability to transmit Bd to their amphibian hosts. We also found that Cx. territans feed primarily on green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana) and that the prevalence of Bd within the frog population at our field site varied between years. CONCLUSIONS: This study provides critical insights into understanding the role of amphibian-biting mosquitoes in transmitting pathogens, which can be applied to disease ecology of susceptible amphibian populations worldwide.

Early life skin microbial trajectory as a function of vertical and environmental transmission in Bornean foam-nesting frogs.

BACKGROUND: The amphibian skin microbiome is an important mediator of host health and serves as a potential source of undiscovered scientifically significant compounds. However, the underlying modalities of how amphibian hosts obtain their initial skin-associated microbiome remains unclear. Here, we explore microbial transmission patterns in foam-nest breeding tree frogs from Southeast Asia (Genus: Polypedates) whose specialized breeding strategy allows for better delineation between vertically and environmentally derived microbes. To facilitate this, we analyzed samples associated with adult frog pairs taken after mating-including adults of each sex, their foam nests, environments, and tadpoles before and after environmental interaction-for the bacterial communities using DNA metabarcoding data (16S rRNA). Samples were collected from frogs in-situ in Brunei, Borneo, a previously unsampled region for amphibian-related microbial diversity. RESULTS: Adult frogs differed in skin bacterial communities among species, but tadpoles did not differ among species. Foam nests had varying bacterial community composition, most notably in the nests' moist interior. Nest interior bacterial communities were discrete for each nest and overall displayed a narrower diversity compared to the nest exteriors. Tadpoles sampled directly from the foam nest displayed a bacterial composition less like the nest interior and more similar to that of the adults and nest exterior. After one week of pond water interaction the tadpole skin microbiome shifted towards the tadpole skin and pond water microbial communities being more tightly coupled than between tadpoles and the internal nest environment, but not to the extent that the skin microbiome mirrored the pond bacterial community. CONCLUSIONS: Both vertical influence and environmental interaction play a role in shaping the tadpole cutaneous microbiome. Interestingly, the interior of the foam nest had a distinct bacterial community from the tadpoles suggesting a limited environmental effect on tadpole cutaneous bacterial selection at initial stages of life. The shift in the tadpole microbiome after environmental interaction indicates an interplay between underlying host and ecological mechanisms that drive community formation. This survey serves as a baseline for further research into the ecology of microbial transmission in aquatic animals.

A new fanged frog in the Limnonectes kuhlii complex (Anura: Dicroglossidae) from northeastern Cambodia.

The Limnonectes kuhlii complex is a group of morphologically similar species of fanged frogs distributed across much of mainland and insular Southeast Asia. Many new species in this complex have been described in recent years, primarily on the basis of mitochondrial DNA divergence corroborated by differences in linear measurements and qualitative characters. Males in this species complex develop enlarged heads at sexual maturity, but the degree of head enlargement varies among mature males, even within the same population. We evaluated the utility of body length (snout-vent length minus head length) in descriptive statistics and in size-adjusting measurements for traditional morphometric analysis, as well as a landmark-based geometric morphometric analysis of male head shape, in Indochinese species of the L. kuhlii complex. The analyses supported quantitative and qualitative morphological distinction of a divergent mitochondrial lineage of the L. kuhlii complex in northeastern Cambodia, and the lineage is described as a new species. Limnonectes fastigatus sp. nov. differs from its closest relatives and from geographically proximate members of the complex by having the combination of elongated, slender odontoids; nuptial pads on the first finger; immaculate belly; significantly different body length-adjusted measurements in both sexes; and a significantly different male head shape. The new species is the only member of the L. kuhlii complex known from Cambodia.

A Quantitative Analysis of Four Undergraduate Human Anatomy Laboratory Curricula: Approaches, Identified Structures, Concepts, and Thematic Emphases.

Human anatomy is a foundational course thatserves diverse pre-professional health care majors. However, limited information is available on the teaching approaches, content, and thematic emphases of this course at the undergraduate level when compared with that of medical and other graduate schools. Herein, we document and quantitatively evaluate the laboratory curriculum of four undergraduate human anatomy courses in the USA. For each course, we assess the total number of structures (terms requiring identification during an exam), concepts (terms requiring an explanation), and clinical applications. To facilitate further assessments, we also compare the content distribution of each course with that recommended by the American Association of Clinical Anatomists (AACA). Two courses followed a regional approach emphasizing the use of human cadavers, while the other two followed a system-based approach and used plastic models and non-human cadaveric materials (e.g., cats and sheep). The total amount of information presented to students differed significantly among curricula. The majority of terms (65-88%) taught to students referred to the identification of anatomical structures whereas clinical applications were rare (< 1.3%). Courses using a regional approach expected students to learn as much as twice the number of terms than those following a system-based approach. Functions, innervations, origins, and insertions of muscles are only included in the curriculum of the courses following a regional approach. The proportion of terms devoted to each anatomical module in all curricula was significantly different from each other, as well as from that of AACA recommendation. We discuss these differences in the curriculum, the challenges and limitations inherent with each teaching approach, as well as in the teaching materials used among the curricula. These quantitative analyses aim to provide insightful information about the structure of the undergraduate human anatomy laboratory curriculum and may prove useful when redesigning a course.

Taxonomic revision of the Chinese Limnonectes (Anura, Dicroglossidae) with the description of a new species from China and Myanmar.

Phylogenetic reconstructions derived from DNA sequence data play a central role in documenting the number of species in a complex. Such analyses are pointing to the existence of many cryptic species, especially in poorly understood groups such as the genus Limnonectes, and the L. kuhlii species complex in particular. To understand the Limnonectes frogs of China, we reconstruct the major matrilineal genealogy of Limnonectes from China and Southeast Asia based on 12S rRNA, tRNAVal and 16S rRNA gene sequences. Based on new data we recognize five species of Limnonectes in China including L. bannaensis, L. fujianensis, L. fragilis, L. taylori (new record), and a new species from southern China and Myanmar. Phylogenetically, the new species is more closely related to the clade comprising L. taylori, L. megastomias, L. isanensis, L. nguyenorum, and L. jarujini from Thailand than to other Chinese species. This study supports previous findings of sympatric members of a species complex that are not each other's closest relatives.

Description of the tadpoles of two endemic frogs: the Phu Luang cascade frog Odorrana aureola (Anura: Ranidae) and the Isan big-headed frog Limnonectes isanensis (Anura: Dicroglossidae) from northeastern Thailand.

We describe the external morphology of the tadpoles of two frogs endemic to Thailand: the Phu Luang cascade frog    (Odorrana aureola) and the Isan big-headed frog (Limnonectes isanensis) from the type localities in the Phu Luang Wildlife Sanctuary, Loei Province, northeastern Thailand. Morphological and genetic characters (16S rRNA) were used to identify specimen and match tadpoles to the adults. Detailed descriptions of external morphology and coloration in life are provided for both species. We provide a brief discussion of the ecology of these tadpoles and a comparison to previously published data from tadpoles of closely related taxa. Additionally, we provide evidence for the utility of larval morphology in resolving the taxonomic puzzles presented by cryptic species complexes.

More of the same: a diminutive new species of the Limnonectes kuhlii complex from northern Vietnam (Anura: Dicroglossidae).

A new species in the dicroglossid genus Limnonectes known only from Ha Giang province, Vietnam is described. Analysis of DNA sequence data from the mitochondrial 12S and 16S gene regions places the species within the Limnonectes kuhlii Complex and demonstrates it to be the sister taxon to an Indochinese clade containing L. isanensis, L. jarujini, L. megastomias, and L. taylori. The new species occurs in syntopy with L. bannaensis. Both molecular and morphological data support the recognition of this lineage as a new species. Notably, the relatively diminutive size of this species distinguishes Limnonectes nguyenorum sp. nov. from all other members of the L. kuhlii Complex.

Re-evaluating the taxonomic status of Chiromantis in Thailand using multiple lines of evidence (Amphibia: Anura: Rhacophoridae).

Because of general phenotypic similarities and distribution of species across two continents, the genus Chiromantis has proven somewhat enigmatic. Among Indochinese species, the validity of C. hansenae has been questioned by some who consider it a junior synonym of C. vittatus. We employ three lines of evidence to elucidate the taxonomic status and phylogenetic relationships of four congeneric species of Chiromantis frogs from Thailand. Results of molecular, morphological, and bioacoustic data analyses support at least four evolutionarily distinct and monophyletic clades: C. doriae, C. nongkhorensis, C. vittatus and C. hansenae. Genetic divergence between C. vittatus and C. hansenae is > 10%, significantly greater than C. doriae and C nongkhorensis (4.5%). Our results support the taxonomic validity of C. hansenae and suggest that there may be more diversity within C. hansenae and C. vittatus than is currently recognized.

Of Least Concern? Systematics of a cryptic species complex: Limnonectes kuhlii (Amphibia: Anura: Dicroglossidae).

Several recent studies have demonstrated that a tremendous amount of biological diversity can be masked by phenotypic similarity in a cryptic species complex. It has been speculated that the widely distributed and relatively common Southeast Asian frog Limnonectes kuhlii represents a complex of multiple species. The phylogeny within the L. kuhlii Complex is estimated in this study based on approximately 2400bp of mtDNA data (tRNA(Phe), 12S, tRNA(Val), and 16S genes) from 244 individuals representing multiple populations from throughout the known distribution of this anuran. Analyses are conducted using parsimony, maximum likelihood and Bayesian methods. The results suggest that what has been recognized historically as a single species is a complex of more than 22 distinct evolutionary lineages, 16 of which are currently subsumed under the nominal L. kuhlii. Several cases of sympatric lineages were detected, and in all cases co-occurring lineages were not each other's closest relatives.