Small mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin and new records for San Martín department, Peru

The Seasonally Dry Tropical Forests in Peru are well known for their bird and plant diversity and endemicity, but little is known about the diversity of small mammals. We report the diversity of small volant and non-volant mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin in the San Martín Department, working on both sides of the river, making a sampling effort of 3060 traps-night for non-volant and 104 mist nets-night for volant mammals. We recorded 29 species, including five marsupials, three rodents, and 21 bats. Among the bats, phyllostomids were the most diverse group with 16 species. Short-tailed Spiny-rat, Proechimys brevicauda (Günther, 1877) and Seba's Short-tailed Bat, Carollia perspicillata (Linnaeus, 1758), featured the highest relative abundance. In addition, we report the first records for the San Martín Department of Peropteryx macrotis (Wagner, 1843), Saccopteryx bilineata (Temminck, 1838), Lonchorhina aurita Tomes, 1863, Vampyriscus bidens (Dobson, 1878), and Myotis simus Thomas, 1901. The species richness and diversity indices indicate the study site has a high diversity value; however, fragmentation and rapid changes in land-use are the main threats faced by the biodiversity of these dry forests.

El Niño-Southern Oscillation affects the water relations of tree species in the Yucatan Peninsula, Mexico

We evaluated the effect of ENSO 2015/16 on the water relations of eight tree species in seasonally dry tropical forests of the Yucatan Peninsula, Mexico. The functional traits: wood density, relative water content in wood, xylem water potential and specific leaf area were recorded during the rainy season and compared in three consecutive years: 2015 (pre-ENSO conditions), 2016 (ENSO conditions) and 2017 (post-ENSO conditions). We analyzed tree size on the capacity to respond to water deficit, considering young and mature trees, and if this response is distinctive in species with different leaf patterns in seasonally dry tropical forests distributed along a precipitation gradient (700–1200 mm year−1). These traits showed a strong decrease in all species in response to water stress in 2016, mainly in the driest site. Deciduous species had lower wood density, higher predawn water potential and higher specific leaf area than evergreen species. In all cases, mature trees were more tolerant to drought. In the driest site, there was a significant reduction in water status, regardless of their leaf phenology, indicating that seasonally dry tropical forests are highly vulnerable to ENSO. Vulnerability of deciduous species is intensified in the driest areas and in the youngest trees.

Plegadis ridgwayi (J.A. Allen, 1876) (Aves, Threskiornithidae): range extension and a new country record for Ecuador

We report the second record of Puna Ibis, Plegadis ridgwayi J.A. Allen, 1876 (Aves, Threskiornithidae), from Ecuador and the first record of this species in seasonally dry tropical forests of the southwest of the country. An individual of P. ridgwayi was sighted in November in Zapotillo, Loja province, 440 km from the only previous record in Ecuador and 65 km from the northernmost Peruvian record. The new record from Ecuador, along with records from the northern coast of Peru, suggests that P. ridgwayi may be expanding its geographic distribution northward in this region.

Phytosociology of a Seasonally Dry Tropical Forest in the State of Michoacán, Mexico

Background: seasonally dry tropical forests are considered critical and important ecosystems because they harbor exceptional biological diversity. Mexico lacks sound phytosociological studies of Seasonally Dry Tropical Forest and Michoacán is no exception. The present study may be regarded the first phytosociological in most of the Mexican pacific coast where seasonally dry tropical forests occurs. Questions/Objective: We aimed at describing the representative plant associations of the seasonally dry tropical forest, distributed on western Michoacán and to provide a sintaxonomic classification framework based on the floristic differentiation of the recognized communities and highlight its phytocenotic diversity. Study site and dates: Estado de Michoacán; 20 years. Methods: A total of 82 phytosociological inventories were conducted. Data were submitted to multivariate two-way indicator species analyses to depict plant communities and their ecological affinities. Results: From its analysis and interpretation, nine plant groups were differentiated, of which all but one was given the rank of association, which are Lysilomo acapulcensis–Heliocarpetum terebinthinacei, Ceibo aesculifoliae–Lysilometum divaricatae, Caesalpinio platylobae-Cordietum elaeagnoidis, Cochlospermo vitifolii-Lueheetum candidae, Lysilomo divaricatae-Cordietum elaeagnoidis; Stenocereo quevedonis-Cordietum selerianae, Guazumo ulmifoliae-Cordietum elaeagnoidis¸ Lonchocarpo huetamoensis-Cordietum elaeagnoidis and the community of Spondias purpurea-Cochlospermum vitifolium. Conclusions: Comparative floristic and structural profiles among plant communities permitted us to distinguish their bioclimatic relationships. Diagnostic species representative of all plant associations were selected and used for sintaxonomic nomenclature. Plant associations were finally array along bioclimatic and altitudinal gradients and showed in arranged phytosociological tables. The plant association/community’descriptions permitted to compare structural physiognomy, floristic composition, ecological affinities, distribution patterns and bioclimatic liaison among them.

Ditaxis (Euphorbiaceae) from the Brazilian Caatinga, including a new species

Ditaxis is a Neotropical genus with approximately 50 species, most of them in seasonally dry tropical forests of Brazil, Central America and the Antilles. The Brazilian Caatinga, the largest area of SDTF in South America, harbors three endemic species of Ditaxis, including the new Ditaxis grazielae, hereby described and illustrated. The new species is known from a few localities in the state of Bahia. We provide an identification key for the species occurring in the Caatinga, as well as comments on habitat, distribution and phenology. We also present amended descriptions and typifications for Ditaxis desertorum and D. malpighiacea, and propose D. gardneri as synonym of D. desertorum.