Different environment, different reproductive strategies? Unexpected field observations in the harvestmen Discocyrtus prospicuus (Laniatores: Gonyleptidae).

The evolution of reproductive strategies depends on the relative balance between current benefits and future costs. Geographic variation in demographic and ecological factors has the potential to affect reproductive strategies by altering this optimal cost-benefit balance. Here, we studied a population of the harvestmen Discocyrtus prospicuus inhabiting an environment never studied before in this context: a tidal freshwater wetland. We made monthly observations of male-female interactions and their association with egg clutches during a two-year field survey. Our results do not match the expected pattern for this species, consisting of males deserting females immediately after copulation, and females laying isolated eggs and abandoning them after oviposition. Conversely, we show for the first-time pairs D. prospicuus, formed by a female and a male, resting together before and after oviposition. Females of this wetland population lay the eggs in small clutches and some of the clutches had eggs in more than one stage of development. Also, we found many females alone over or near the egg clutch in the typical resting position. These findings markedly widen the behavioral specter previously reported for this species and set the stage for future research to determine the causes of these variations.

A closer look at pupil diversity and evolution in frogs and toads.

The eyes of frogs and toads (Anura) are among their most fascinating features. Although several pupil shapes have been described, the diversity, evolution, and functional role of the pupil in anurans have received little attention. Studying photographs of more than 3200 species, we surveyed pupil diversity, described their morphological variation, tested correlation with adult habits and diel activity, and discuss major evolutionary patterns considering iris anatomy and visual ecology. Our results indicate that the pupil in anurans is a highly plastic structure, with seven main pupil shapes that evolved at least 116 times during the history of the group. We found no significant correlation between pupil shape, adult habits, and diel activity, with the exception of the circular pupil and aquatic habits. The vertical pupil arose at least in the most-recent common ancestor of Anura + Caudata, and this morphology is present in most early-diverging anuran clades. Subsequently, a horizontal pupil, a very uncommon shape in vertebrates, evolved in most neobatrachian frogs. This shape evolved into most other known pupil shapes, but it persisted in a large number of species with diverse life histories, habits, and diel activity patterns, demonstrating a remarkable functional and ecological versatility.

Phylogenetic relationships of the Boana pulchella Group (Anura: Hylidae).

In this paper we present a phylogenetic analysis of the treefrogs of the Boana pulchella Group with the goals of (1) providing a rigorous test of its monophyly; (2) providing a test of relationships supported in previous studies; and (3) exploring the relationships of the several species not included in previous analyses. The analyses included>300 specimens of 37 of the 38 species currently included in the group, plus 36 outgroups, exemplars of the diversity of Boana and the other genera of the hylid tribe Cophomantini. The dataset included eight mitochondrial genes (12S, 16S, CytB, COI, ND1, tRNAIle, tRNALeu, and tRNAVal) and five nuclear genes (RHO, TYR, RAG-1, CXCR4, SIAH1). The phylogenetic analyses recover the monophyly of the B. pulchella Group with lower support than previous studies, as a result of the inclusion of the B. claresignata Group, which is recovered as its sister taxon. Within the B. pulchella Group, the inclusion of almost all species of the group had little impact on previous notions of its phylogeny, except for the rejection of the hypothesized B. polytaenia Clade (B. goiana and B. phaeopleura are nested in the clade here called the B. prasina Clade), which is redefined. Phylogenetic support is strong for five major clades, which collectively include all but three of the species sampled: the B. balzani Clade (B. aguilari, B. balzani, B. gladiator, B. melanopleura, B. palaestes), the redefined B. polytaenia Clade (B. botumirim, B. buriti, B. cipoensis, B. jaguariaivensis, B. leptolineata, B. polytaenia, B. stenocephala, and two undescribed species), the B. prasina Clade (B. bischoffi, B. caingua, B. cordobae, B. goiana, B. guentheri, B. marginata, B. phaeopleura, B. prasina, B. pulchella, and one undescribed species), the B. riojana Clade (B. callipleura, B. marianitae, B. riojana), and the B. semiguttata Clade (B. caipora, B. curupi, B. joaquini, B. poaju, B. semiguttata, B. stellae, and two undescribed species). The monophyly of the B. prasina + B. riojana Clades, and that of the B. polytaenia + B. semiguttata Clades are well-supported. The relationships among these two clades, the B. balzani Clade, B. ericae + B. freicanecae, and B. cambui (representing the deepest phylogenetic splits within the B. pulchella Group) are recovered with weak support. We discuss the phenotypic evidence supporting the monophyly of the B. pulchella Group, and the taxonomy of several species, identifying three new synonyms of Boana polytaenia, one new synonym of Boana goiana, and one new synonym of B. riojana.

Population dynamics and reproductive phenology of a harvestman in a tidal freshwater wetland.

There is a great amount of ecological information for terrestrial arthropods in several types of habitats, but few studies have focused on populations living in tidal freshwater wetlands. During a two-year field survey, we studied the temporal dynamics of the harvestman Discocyrtus prospicuus inhabiting a freshwater wetland exposed to predictable tides and unpredictable floods. We also explored the effects of temperature, precipitation, and tide level on the population dynamics and reproductive phenology. Our findings are markedly different from those reported in other harvestman species living in different habitats and also from conspecific populations living in the mainland. Adults, subadults, and juveniles remain active throughout the year, and a long breeding season was observed. However, the number of adults, subadults, juveniles, and egg clutches showed clear variations over the year without a consistent seasonal pattern. Contrary to the general pattern in harvestmen, no climatic variables were significant predictors of abundance fluctuations. We discuss the potential masking effect of unpredictable flood events, obscuring the relationship between abundance and abiotic factors. In addition, given that climatic conditions seem to favor harvestmen activity throughout the year, we also hypothesized that abundance variations could be driven mainly by biotic rather than by abiotic interactions.

Phylogenetic relationships of toads of the Rhinella granulosa group (Anura: Bufonidae): a molecular perspective with comments on hybridization and introgression.

The Rhinella granulosa group consists of 13 species of toads distributed throughout open areas of South America and Panama. In this paper we perform a phylogenetic analysis considering all but one species of the group, employing five nuclear and four mitochondrial genes, for up to 7910 bp per specimen. Separate phylogenetic analyses under direct optimization (DO) of nuclear and mitochondrial sequences recovered the R. granulosa group as monophyletic and revealed topological incongruence that can be explained mainly by multiple events of hybridization and introgression, both mitochondrial and nuclear. The DO combined analysis, after the exclusion of putatively introgressed or heterozygous genomes, resulted in a phylogenetic hypothesis for the R. granulosa group in which most of the species are recovered as monophyletic, but with interspecific relationships poorly supported. The optimization of morphological (adult and larval), chromosomal, and behavioural characters resulted in 12 putative phenotypic synapomorphies for this species group and some other synapomorphies for internal clades. Our results indicate the need for additional population genetic studies on R. dorbignyi and R. fernandezae to corroborate the taxonomic status of both taxa. Finally, we discuss biological and genetic characteristics of Bufonidae, as possible explanations for the common occurrence of hybridization and introgression observed in some lineages of this family.

A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinax uruguayus group).

The genus Scinax currently includes more than 120 species, recovered in two major clades, the S. catharinae and the S. ruber clades. The latter comprises 75 species, most of which remain unassigned to any species groups, while 12 are included in the S. rostratus and S. uruguayus groups. In this paper we present a taxonomic review of the two species currently included in the S. uruguayus group, discussing some putative phenotypic synapomorphies of this group. Although S. pinima and S. uruguayus have been considered as distinct species, this has been based on scant evidence, and several authors doubted of their distinctiveness. Our study of available specimens of S. pinima and S. uruguayus corroborates that both are valid and diagnosable species based on phenotypic evidence. Furthermore, our results show that S. pinima previously known only from its type locality, has a much widespread distribution than previously thought (including the Brazilian states of Paraná, Santa Catarina, and Rio Grande do Sul), which, added to the biological information presented here allows to suggest the removal of this species from the "Data Deficient" IUCN Red List category to "Least Concern". Also, we describe a new species formerly reported as S. aff. pinima and S. uruguayus from NE Argentina and some localities from the Brazilian State of Rio Grande do Sul. All species are diagnosed and characterized using adult and larval morphology, osteology, vocalizations, cytogenetics, and natural history.

Correction: A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinax uruguayus group).

[This corrects the article DOI: 10.1371/journal.pone.0222131.].

A new species of Physalaemus (Anura, Leptodactylidae) from the Atlantic Forest of Misiones, northeastern Argentina.

A new species of Physalaemus from Misiones province, Argentina, in the Atlantic forest domain is described. The new species is a member of the P. gracilis group, based on its phylogenetic position and the occurrence of a putative morphological synapomorphy (occurrence of an unpigmented median stripe on throat, chest, and/or abdomen). Physalaemus sp. nov. is characterized by a long advertisement call composed of non-pulsed notes with slightly descendant modulation, large size (mean SVL = 32.0 mm males, 34.0 mm females), slender body aspect, head longer than wide, supratympanic fold developed, an unpigmented median stripe on venter, medium sized inguinal glands, tarsal tubercle present, and supernumerary tubercles on hands and feet, which are character states that combined distinguish the new species from all the members of the genus. In this study, we provide its formal description based on external morphology, advertisement call, and 16S genetic distance. In addition, the distribution ranges for the new species and P. gracilis are revisited, the advertisement call of P. gracilis is redescribed, and a discussion about the available names which could be applicable to the new species is provided.

Concentrated evolutionary novelties in the foot musculature of Odontophrynidae (Anura: Neobatrachia), with comments on adaptations for burrowing.

We studied the foot musculature of the fossorial family Odontophrynidae (composed of the genera Macrogenioglottus, Odontophrynus, and Proceratophrys) plus several outgroup taxa from Hyloidea and other burrowing taxa from across Anura. We found novel character-states supporting the monophyly of Odontophrynus, Proceratophrys, and Odontophrynus + Macrogenioglottus. The character-states observed in O. cultripes support conflicting phylogenetic positions within Odontophrynus. A comparison of some novel character-states with a diverse sample of burrowing taxa suggests that some modifications of the foot musculature might be involved in digging.

The complex evolutionary history of the tympanic middle ear in frogs and toads (Anura).

Most anurans possess a tympanic middle ear (TME) that transmits sound waves to the inner ear; however, numerous species lack some or all TME components. To understand the evolution of these structures, we undertook a comprehensive assessment of their occurrence across anurans and performed ancestral character state reconstructions. Our analysis indicates that the TME was completely lost at least 38 independent times in Anura. The inferred evolutionary history of the TME is exceptionally complex in true toads (Bufonidae), where it was lost in the most recent common ancestor, preceding a radiation of >150 earless species. Following that initial loss, independent regains of some or all TME structures were inferred within two minor clades and in a radiation of >400 species. The reappearance of the TME in the latter clade was followed by at least 10 losses of the entire TME. The many losses and gains of the TME in anurans is unparalleled among tetrapods. Our results show that anurans, and especially bufonid toads, are an excellent model to study the behavioural correlates of earlessness, extratympanic sound pathways, and the genetic and developmental mechanisms that underlie the morphogenesis of TME structures.