Stable isotope analyses of web-spinning spider assemblages along a headwater stream in Puerto Rico.

Web-spinning spiders that inhabit stream channels are considered specialists of aquatic ecosystems and are major consumers of emerging aquatic insects, while other spider taxa are more commonly found in riparian forests and as a result may consume more terrestrial insects. To determine if there was a difference in spider taxa abundance between riverine web-spinning spider assemblages within the stream channel and the assemblages 10 m into the riparian forest, we compared abundances for all web-spinning spiders along a headwater stream in El Yunque National Forest in northeast Puerto Rico. By using a nonmetric dimensional scaling (NMDS) abundance analysis we were able to see a clear separation of the two spider assemblages. The second objective of the study was to determine if aquatic insects contributed more to the diet of the spider assemblages closest to the stream channel and therefore stable isotope analyses of δ (15)N and δ (13)C for web-spinning spiders along with their possible prey were utilized. The results of the Bayesian mixing model (SIAR) however showed little difference in the diets of riverine (0 m), riparian (10 m) and upland (25 m) spiders. We found that aquatic insects made up ∼50% of the diet for web-spinning spiders collected at 0 m, 10 m, and 25 m from the stream. This study highlights the importance of aquatic insects as a food source for web-spinning spiders despite the taxonomic differences in assemblages at different distances from the stream.

Antropometría del yunque y articulaciones incudo-maleolar e incudo-estapedial en humanos: un estudio anatómico directo / Anthropometry of the incus and incudomalleolar and incudostapedial joints in humans: a direct anatomical study

Los estudios actuales sobre variaciones anatómicas del yunque en humanos a partir del registro morfométrico son insuficientes. Las características estructurales y dimensionales del yunque son registradas en 23 muestras de población mestiza adulta Colombiana. Las medidas registradas involucraron el cuerpo, la articulación incudo-maleolar, el proceso largo, el proceso corto y la articulación incudo-estapedial. Solo ocho de los treinta y cinco registros tomados en este estudio pudieron ser comparados concienzudamente con otros estudios anteriores que mostraron similitudes. El largo total del yunque fue de 6,51 mm (DE 0,32), la longitud del proceso largo del yunque fue de 5,35 mm (DE 0,25), la distancia entre proceso largo y corta fue de 6,06 mm (DE 0,35) y la proporción de longitudes entre ambos procesos fue de 82,18 por ciento (DE 8,9). Conforme a la población estudiada se encontró variación pareada en la anatomía del yunque en solo tres de los registros tomados, sin embargo, consideramos que es un hueso morfométricamente uniforme y estable.

Current studies on anatomical variations of the incus in humans from the morphometric register are insufficient. Structural and dimensional characteristics of the incus are registered in 23 samples of Colombian adult mestizo population. Registered measures involved incus body, incudo-maleolar joint, long process, short process and incudo-stapedial joint. Only eight of the thirty-five records taken in this study could be thoroughly compared to other anterior studies, which showed similarities. The total length of the anvil was 6,51 mm (SD 0.32), the length of the long process of the incus was 5.35 mm (SD 0.25), the distance between processes long and short was 6.06 mm (SD 0.35) and the ratio of lengths between both processes was 82.18 percent (SD 8.9 percent). In accordance with the studied population we found paired variation in the anatomy of the incus in only three of the records taken, however, we believe that it is a uniform and morphometrically stable bone.