Russulaceae and Thelephoraceae form ectomycorrhizas with members of the Nyctaginaceae (Caryophyllales) in the tropical mountain rain forest of southern Ecuador

* Three members of the Nyctaginaceae, two Neea species and one Guapira species, occurred scattered within a very species-rich neotropical mountain rain forest. The three species were found to form ectomycorrhizas of very distinctive characters, while all other tree species examined formed arbuscular mycorrhizas. * The ectomycorrhizas were structurally typified according to light and transmission electron microscope investigations. The internal transcribed spacer (ITS) rDNA and part of the nuclear large subunit (LSU, 28S) rDNA of the mycorrhiza forming fungi were amplified and sequenced. Phylogenetic analyses were carried out. * Neea species 1 was found to form typical ectomycorrhizas with five different fungal species, Russula puiggarii, Lactarius sp., two Tomentella or Thelephora species, and one ascomycete. Neea species 2 and the Guapira species were associated with only one fungus each, a Tomentella/Thelephora species clustering closely together in an ITS-neighbour-joining tree. The long and fine rootlets of the Guapira species showed proximally a hyphal mantle and a Hartig net, but distally intracellular fungal colonization of the epidermis and root hair development. The ectomycorrhizal segments of the long roots of Neea species 2 displayed a hyphal mantle and a Hartig net around alive root-hair-like outgrowths of the epidermal cells. * The distribution and the evolution of ectomycorrhizas in the predominantly neotropic Nyctaginaceae are discussed.     

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae)

• Cycling of sensitivity to physical dormancy (PY) break has been documented in herbaceous species. However, it has not been reported in tree seeds, nor has the effect of seed size on sensitivity to PY‐breaking been evaluated in any species. Thus, the aims of this study were to investigate how PY is broken in seeds of the tropical legume tree Senna multijuga, if seeds exhibit sensitivity cycling and if seed size affects induction into sensitivity.
• Dormancy and germination were evaluated in intact and scarified seeds from two collections of S. multijuga. The effects of temperature, moisture and seed size on induction of sensitivity to dormancy‐breaking were assessed, and seasonal changes in germination and persistence of buried seeds were determined. Reversal of sensitivity was also investigated.
• Fresh seeds were insensitive to dormancy break at wet–high temperatures, and an increase in sensitivity occurred in buried seeds after they experienced low temperatures during winter (dry season). Temperatures ≤20 °C increased sensitivity, whereas temperatures ≥30 °C decreased it regardless of moisture conditions. Dormancy was broken in sensitive seeds by incubating them at 35 °C. Sensitivity could be reversed, and large seeds were more sensitive than small seeds to sensitivity induction.
• Seeds of S. multijuga exhibit sensitivity cycling to PY‐breaking. Seeds become sensitive during winter and can germinate with the onset of the spring–summer rainy season in Brazil. Small seeds are slower to become sensitive than large ones, and this may be a mechanism by which germination is spread over time. Sensitive seeds that fail to germinate become insensitive during exposure to drought during summer. This is the first report of sensitivity cycling in a tree species.

     

Endemic bird species and conservation in the Cerrado Region, South America

A general overview of the largest South American savanna region, the Cerrado Region, is presented. Using simple approaches, I analyse the distribution of the bird species endemic to this region in order to test the hypothesis that areas harbouring local aggregates of restricted-range endemics have remained stable during the successive Quaternary climatic-vegetational changes. This hypothesis seems not to be generally valid for birds of the Cerrado Region, as restricted-range endemic species exist both in areas that remained stable (Central Goia´s Plateau) and areas that remain unstable (Araguaya and Parana~ River valleys, Espinhac¸o Plateau) during the Late Pleistocene. I also discuss some aspects of the conservation in the Cerrado Region, and suggest that the dry forests of the River Parana~ Valley, Goia´s, must be considered the area with the highest priority for the creation of new reserves in the Cerrado Region.     

Jenynsia lineata species complex,revision and new species description (Cyprinodontiformes: Anablepidae)

The Jenynsia lineata species complex comprises J. lineata from Montevideo, Uruguay and Jenynsia multidentata, from coastal basins of Brazil, Uruguay and Argentina up to 1200 m a.s.l. Taxonomic divisions within this group were tested using three different species delimitation methods, which found the two existing names to be synonyms and revealed a new cryptic species. Jenynsia darwini sp. nov. is distinguished from all congeners by having a unique combination of character states, including the shape of the dorsal postcleithrum (three times higher than wide v. less than two times higher than wide) and female colour pattern in the half of the caudal peduncle with rows of chromatophores segmented in unaligned spots (v. aligned spots forming lines). The new species also differs from J. lineata by having 26 nucleotide substitutions in the mitochondrial gene cytochrome c oxidase I (coI). Phylogenetic analysis of the genus based on morphological characters proposed by previous studies corroborates monophyly of the subgenera Plesiojenynsia and Jenynsia, with the new species being allocated to the subgenus Jenynsia as the sister group of J. lineata.     

Intraspecific genetic differentiation of Leporinus friderici (Anostomidae, Pisces) in French Guiana and Brazil: a genetic approach to the refuge theory

A genetic study was carried out on a neotropical fish species to illustrate the refuge theory, whose main principles are summarized. The geographical structure of the anostomid species Leporinus friderici was analysed in French Guiana and Brazil by horizontal starch gel electrophoresis. Fifteen enzymatic systems corresponding to 21 loci were studied, revealing the following particularities: (1) specimens of fish from six independent coastal rivers of French Guiana form two groups geographically situated on either side of the Kourou River; (2) two alleles can serve as geographic markers, Ldh2 ( l30 ) showing an affinity between the populations in eastern French Guiana and Brazil, and Me 1 ( 300 ) being specific to the west.
These observations are probably related to the refuges that were formed in the Quaternary in South America, especially on the Guiana Shield. We consider that the populations of French Guiana are separated into two groups at the boundary between the two migratory flows, one arising in the west from the refuge of the Guiana Shield and the other in the east from a nearby undetermined Amazonian refuge.     

Length–weight relation of the 14 fish species occurring on sandy beaches along a tropical river in the Amazon

We analyzed the length‐weight relation (LWRs) of 14 species of fish, sampled in 30 sandy beaches along the Acre river, encompassing approximately 300 km of the river between the municipalities of Brasileia and Rio Branco, Acre state, Brazil, during the draught period in 2017 (August and September). For sampling, we used a picaré type trawl with 9 m of length, 2 m of height and 5 mm mesh between opposing knots, during the day and night periods. New information was made available for eight fish species.     

Rapid adjustments of migration and life history in hemisphere-switching cliff swallows

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Mapping migration in a songbird using high‐resolution genetic markers

Neotropic migratory birds are declining across the Western Hemisphere, but conservation efforts have been hampered by the inability to assess where migrants are most limited—the breeding grounds, migratory stopover sites or wintering areas. A major challenge has been the lack of an efficient, reliable and broadly applicable method for measuring the strength of migratory connections between populations across the annual cycle. Here, we show how high‐resolution genetic markers can be used to identify genetically distinct groups of a migratory bird, the Wilson's warbler (Cardellina pusilla), at fine enough spatial scales to facilitate assessing regional drivers of demographic trends. By screening 1626 samples using 96 highly divergent single nucleotide polymorphisms selected from a large pool of candidates (~450 000), we identify novel region‐specific migratory routes and timetables of migration along the Pacific Flyway. Our results illustrate that high‐resolution genetic markers are more reliable, precise and amenable to high throughput screening than previously described intrinsic marking techniques, making them broadly applicable to large‐scale monitoring and conservation of migratory organisms.     

Ongoing speciation within the Anastrepha fraterculus cryptic species complex: the case of the Andean morphotype

The Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) cryptic species complex is currently composed of seven taxonomically recognized morphotypes. Both, pre‐ and post‐zygotic isolation has been documented among four of these morphotypes, revealing that in fact they appear to be distinct biological entities. In order to progress in the full delimitation of species within the complex, we examined reproductive isolation between a Colombian population of the Andean morphotype and populations belonging to four other morphotypes spanning from Mexico to Argentina. Flies from the Andean morphotype exhibited strong pre‐zygotic mating isolation through temporal partitioning of mating activity. Post‐zygotic isolation was observed for crosses of males of all morphotypes and Andean morphotype females, yet most of the F1 hybrid ♂ × F1 hybrid ♀ self‐crosses showed normal levels of fertility, a finding suggesting a nuclear–cytoplasmic interaction according to previous studies. Overall, the Andean morphotype within the complex also appears to be a distinct biological entity. We discuss the implications of these findings for the understanding of speciation mechanisms in the Neotropical genus Anastrepha.     

A new species of Astyanax Baird & Girard (Characiformes: Characidae) from the Rio Paraguaçu basin,Chapada Diamantina,Bahia, Brazil,with comments on bony hooks on all fins

A new species of Astyanax from the Rio Paraguaçu basin, Bahia, Brazil, is described. This new species is distinguished from its congeners known to occur in Brazilian drainages by the presence of small bony hooks on all fins of mature males. Furthermore, the new species can be diagnosed by its colour pattern, which consists of a unique vertically elongated humeral blotch, a conspicuous dark drop‐shaped horizontal blotch over the caudal peduncle, tapering anteriorly and not extending to the median caudal‐fin rays, and by the absence of a conspicuous broad dark midlateral stripe. The new species differs further by having the greatest body depth just anterior to the dorsal‐fin origin, 32–35 perforated scales in the lateral line and a reduced number of branched anal‐fin rays (16–20). Apparently, the new species does not fit into any species complex of Astyanax. The occurrence of bony hooks on all fins of Astyanax is discussed.