The efferent ducts of the Mediterranean Gecko, Hemidactylus turcicus (Gekkonidae) were investigated using light and electron microscopy. The seminiferous tubules unite into a single rete testis tubule. The rete testis divides into 3-4 ductuli efferentes which all drain into the cranial portion of the ductus epididymis. All efferent ducts are most active during the months of December to August. The rete testis is composed of a simple squamous epithelium with bifurcated nuclei and a labyrinthine network of intercellular canaliculi. Ciliated and nonciliated cells are present, and more than one cilium extends from the scattered ciliated cells. The presence of small clear vesicles and widened intercellular canaliculi suggest that cells of the rete testis are responsible for intake of luminal fluids. The ductuli efferentes are composed of a simple cuboidal epithelium consisting of ciliated and nonciliated cells, and ciliated cells are the dominant cell type. During the inactive season the number of lysosomes increases and the cells become spermiophagic. The ductus epididymis is composed of a tall pseudostratified columnar epithelium with relatively scarce basal cells. No evidence for regionalization was observed. The ductus epididymis is highly secretory during the active season with numerous electron-dense secretory granules, whose glycoprotein products are released by merocrine secretion. Basally, the active epididymis has swollen intercellular canaliculi and enlarged cisternae of rough endoplasmic reticulum. During the inactive season the secretory activity decreases and membranous structures and fibrous material are observed within widened intercellular canaliculi apical to the basal cells. Anat Rec, 293:2176Rec, 293: -2192

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Quantifying assemblage structure across spatio-temporal scales is ecologically important and further aids in the understanding of community organisation processes. Currently, few studies have assessed assemblage structure across generous magnitudes of scale, and influences of processes (biotic and abiotic) responsible for structuring assemblages are still questioned. Using community and hydrologic data collected over a 22-year period from a stretch of river nearing 150 km, we examined spatio-temporal fish assemblage structural patterns in a temperate coastal plain stream. Results indicated that significant changes in assemblage structure across time were influenced by environmental disturbances, including drought and hurricane events. Assemblages were restructured in a punctuated manner directly following these events, and complete recovery of initial assemblage structure did not occur across the study period. Additionally, we found spatial differentiations between upstream and downstream assemblages, which were driven by greater abundances of several species in downstream sites. Our results suggest that assemblage structure is influenced by environmental variation, specifically, extreme disturbance events and spatial habitat heterogeneity.

A new species of slender skink is described from the Philippines. The species is endemic to Lubang Island, and is assigned to the Brachymeles bonitae Complex based on phenotypic and genetic data. Specimens were collected from Lubang Island between 1991 and 2012, and were examined based on morphological data (qualitative traits, meristic counts, and mensural measurements). Published genetic sequence data from phylogenetic studies of the genus reveal the new species to be highly divergent from congeners. Brachymeles ligtas sp. nov. is differentiated from other members of the genus based on a number of distinct morphological features, including small body size (SVL 60.7-79.6 mm), bidactyl fore-limbs, digitless hind limbs, high number of presacral vertebrae (50), and the absence of auricular openings. Additionally, the new species has diagnostic, distinct dorsal head scale patterns. This new species becomes the only member of the genus known to occur on the deep-ocean island of Lubang.

Anthropogenic perturbations impact aquatic systems causing wide-ranging responses, from assemblage restructuring to assemblage recovery. Previous studies indicate the duration and intensity of disturbances play a role in the dynamics of assemblage recovery. In August 2011, the Pearl River, United States, was subjected to a weak black liquor spill from a paper mill which resulted in substantial loss of fish in a large stretch of the main channel. We quantified resilience and recovery of fish assemblage structure in the impacted area following the event. We compared downstream (impacted) assemblages to upstream (unimpacted) assemblages to determine initial impacts on structure. Additionally, we incorporated historic fish collections (1988–2011) to examine impacts on assemblage structure across broad temporal scales. Based on NMDS, upstream and downstream sites generally showed similar assemblage structure across sample periods with the exception of the 2 months postdischarge, where upstream and downstream sites visually differed. Multivariate analysis of variance (PERMANOVA) indicated significant seasonal variation among samples, but found no significant interaction between impacted and unimpacted assemblages following the discharge event. However, multivariate dispersion (MVDISP) showed greater variance among assemblage structure following the discharge event. These results suggest that 2 months following the disturbance represent a time period of stochasticity in regard to assemblage structure dynamics, and this was followed by rapid recovery. We term this dynamic the “hangover effect” as it represents the time frame from the cessation of the perturbation to the assemblage's return to predisturbance conditions. The availability and proximity of tributaries and upstream refugia, which were not affected by the disturbance, as well as the rapid recovery of abiotic parameters likely played a substantial role in assemblage recovery. This study not only demonstrates rapid recovery in an aquatic system, but further demonstrates the value of continuous, long-term, data collections which enhance our understanding of assemblage dynamics.

Understanding how biotic and abiotic processes influence community assembly is a fundamental aim in ecology. Although spatial scales at which communities are studied may affect the relative importance of such assembly processes, spatial influences on community assembly have not been thoroughly addressed. We tested how spatial scale affects inferences of habitat filtering and competitive exclusion assembly processes in darter (Percidae: Etheostomatinae) assemblages across four temperate stream systems. We predicted competitive exclusion would influence assembly in fine-scale assemblages, and habitat filtering would be more influential as spatial scale increased. Moreover, we assumed that habitat heterogeneity would increase with scale, and consequently alleviate direct competitive exclusion acting at finer scales. Using a framework that incorporated genetic relatedness, morphological traits, and habitat use among co-occurring darter species, we identified ecological and evolutionary patterns of structure, which allowed us to elucidate processes of assembly. Based on phylogenetic structure, assemblages showed an increase in habitat filtering (i.e., increased phylogenetic clustering) as we scaled up from fine to intermediate assemblages; however, we found mixed signals for habitat filtering and competitive exclusion at the broadest spatial scale. While habitat filtering was found to have an overall high relative importance during assembly, we also found influence of competitive exclusion processes based on limited morphological similarity among co-occurring species. Our results generally support an increased influence of habitat filtering processes in broader scale assemblages. Moreover, we suggest that habitat filtering and competitive exclusion processes act simultaneously during assembly, although the relative influence of each process may be spatial-scale dependent.

We describe a new digitless scincid lizard of the genus Brachymeles from northern Luzon and Camiguin Norte islands in the Philippines. This species belongs to the Brachymeles bonitae Complex, and both molecular and morphological data confirm that this species is distinct from all other congeners. Formerly considered to be a single widespread species, this group of species has been the focus of recent systematic reviews. Here we describe a new species in the B. bonitae Complex, recognized currently to constitute five species. Brachymeles ilocandia sp. nov. is the second digitless and the seventeenth non-pentadactyl species in genus. The description of this species brings the total number of species in the genus to 40, and provides new insight into unique distribution patterns of species of the northern Philippines.

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