The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study

The Neotropical catfishes of the genus Auchenipterus Valenciennes (1840) are reviewed. The genus is hypothesized to be a monophyletic assemblage on the basis of the shared presence of grooves in the ventral surface of the head that accommodate adducted mental barbels. A possible second synapomorphy, the presence of papillae on the dorsal and medial surface of the ossified maxillary barbel of mature males, is tentatively advanced pending discovery of adult males of three species. Contrary to previous hypotheses which considered Auchenipterus to consist of a maximum of five species, we recognize 11 species, including two previously undescribed forms, A. britskii and A. menezesi: Auchenipterus is broadly distributed through the Rio Orinoco, Rio Amazonas, and Rio de La Plata basins, and the coastal drainages of the Guianas, with one species in the Rio Pindare-Mirim and Rio Parnaiba basins of northeastern Brazil. Auchenipterus nuchalis, previously thought to be broadly distributed across the range of the genus, is found to rather have a restricted distribution in the eastern portions of the Amazon basin, the lower portions of the Rio Tocantins, and lower courses of some rivers in Suriname and French Guiana. Citations of A. nuchalis from elsewhere in the range of the genus are of other species. Euanemus Müller & Troschel (1842) and Ceratocheilus Miranda Ribeiro (1918) are considered synonyms of Auchenipterus. Euanemus colymbetes Müller & Troschel (1842) is considered a synonym of Auchenipterus (fen/ata Valenciennes (1840), and A. paysanduanus Devincenzi (1933) is placed into the synonymy of A. nigripinnis Boulenger (1895). A neotype is designated for Hypopthalmus nuchalis Spix & Agassiz (1829). Lectotypes are designated for Euanemus colymbetes and Auchenipterus nigripinnis.     

The RCE: a Riparian, Channel, and Environmental Inventory for small streams in the agricultural landscape

1. The Riparian, Channel and Environmental (RCE) Inventory has been developed to assess the physical and biological condition of small streams in the lowland, agricultural landscape. It consists of sixteen characteristics which define the structure of the riparian zone, stream channel morphology, and the biological condition in both habitats. 2. The inventory is based on the view that in landscapes where non-point source pollution and agriculture dominate, the environmental condition of small streams can be assessed by an appraisal of the physical condition of the riparian zone and stream channel. It is assumed that disturbance of this physical structure is a major cause for reduction of stream biological structure and function. This assumption is supported by a case study using fifteen Italian stream locations in which the RCE was found to be positively correlated to the benthic macroinvertebrate community as measured by the Extended Biotic Index (r = 0.80, P < 0.001) and the Shannon Diversity Index (r = 0.73; P < 0.001). 3. The inventory is designed for quick use to cover a large number of streams in a short period of time. When used it generates a numerical score which can be used to compare the physical and biological condition between different streams within a region. The numerical score is divided into five, colour-coded classes to facilitate use in streammonitoring programmes and to allow comparison with biological indices.     

Northern Goshawk Habitat: an Intersection of Science,Management, and Conservation

Abstract: We responded to the claim by Greenwald et al. (2005) that the management recommendations for the northern goshawk in the Southwestern United States (MRNG; Reynolds et al. 1992), a food web-based conservation plan that incorporated both northern goshawk (Accipiter gentilis) and multiple prey habitats, may be inadequate to protect goshawks. Greenwald et al. (2005) based this claim on their review of 12 telemetry studies of goshawk habitat selection and 5 nontelemetry studies of the effects of vegetation structure at the home range scale on goshawk nest occupancy and reproduction that appeared after the 1992 publication of the MRNG. Greenwald et al. (2005) summarized their review as showing that 1) goshawks were habitat specialists limited to forests with mature and old-growth structures including large trees, high canopy cover, multiple canopy layering, and abundant woody debris; 2) habitats were not selected on the basis of prey abundance and, therefore, managing for prey habitats diluted goshawk habitats; and 3) selection for openings, edges, and habitat diversity was inconclusive. Our review found that when the studies' respective authors pooled their radiotagged goshawks there were weak to strong selections for old forest structures. However, the studies also documented extensive variation in use of vegetation types and structures by individual goshawks; some avoided openings, edges, young forests, and old forests, whereas others selected for these characteristics. Additionally, by virtue of their wide geographic distribution, the studies showed that the focal populations themselves occurred in a variety of forest types, some with large structural differences. We found no evidence in Greenwald's et al. (2005) review that the MRNG are inadequate to protect goshawks. Rather, the studies reviewed by Greenwald et al. (2005), as well as many studies they missed, supported the MRNG. The suggestion of inadequacy by Greenwald et al. (2005) appeared rooted in misunderstandings of goshawk habitats described in the MRNG, a discounting of the extent of variation in vegetation structural and seral stages used by goshawks, a limited understanding of the extent to which prey limits goshawks, a failure to recognize the dynamic nature of forests, and an incomplete review of the literature. We believe the MRNG are adequate because they maximize the sustainable amount of mature and old forests in goshawk home ranges and specify the kinds and intermixtures of prey habitats within home ranges. Implementation of MRNG should reduce the likelihood that the availability of vegetation structures suited to goshawk nesting and foraging, as well as abundance and availability of prey, will limit goshawk nest occupancy and reproduction.     

Osmoregulation in Larvae of the Land-Crab, Cardisoma guanhumi Latreille

Daily studies were made of the osmoregulatory abilities of Cardisomaguanhumi from hatching to the end of larval development. Theseresults were compared to those of similar research on osmoregulationby larvae and megalopa of four species of estuarine, littoral,and sub-littoral crabs. The comparison shows that larvae ofC. guanhumi possess the same kinds of adaptations for waterintake at the time of molt that were found in Rhithropanopeusharrisii. Land-crab larvae hyperregulated in 10 p.p.t. sea waterand hyporegulated in water of 40 p.p.t. for experimental periodsfor 2 hr during the first one-third of their development. Duringthe remainder of larval life, they hyporegulated against 15p.p.t. in intermolt periods and became isosmotic with, or hyporegulatedagainst, 10 p.p.t. at the time of molting. From the time ofhatching, the osmoregulatory pattern of developing C. guanhumifits them for deep penetration of estuaries and for crossingsteep saline gradients. This pattern is evidence for a strongerand more enduring control of water balance, especially at thetime of molting, than we have found in non-terrestrial species.     

Differentiating Type i and Type ii Alveolar Cells in Rat Lung by OsO4NaI Staining

The fixing-staining mixture consisted of 1 part of 2% aqueous OsO₄ and 3 parts of 3% Nal in distilled water. Fresh lungs were cut into 2 mm slices and immersed in this solution for 24 hr at room temperature. Controls were fixed in buffered OsO₄ alone. Selective staining of type II alveolar cells was shown by the OsO_t-NaI mixture but was absent in the controls. No additional staining of the sections was required, and the selectivity was readily observable in either paraffin or Araldite sections by light microscopy and in Araldite sections by electron microscopy     

Allometric Root/Shoot Relationships and Predicted Water Uptake for Desert Succulents

Root morphology, shoot morphology, and water uptake for Agavedeserti and Ferocactus acanthodes of various sizes were studiedusing allometric relationships (y = ax^b) and a previously developedwater uptake model. Shoot surface area increased with shootvolume with an exponent b of 0.75 for both species. Root lengthand the ground area explored by the roots increased with shootsurface area with b's of 0.72 for A. deserti and 0.92 for F.acanthodes. Various sized individuals had about the same ratioof root length to explored ground area, with higher values occurringfor A. deserti. Predicted water uptake averaged over the exploredground area was approximately constant over a 10⁴-fold rangein shoot surface area, suggesting that shoot size confers nointraspecific competitive advantage for water uptake. For theroot lengths per explored ground area observed in the field,water uptake was predicted to be 85 per cent of maximal; wateruptake could be increased by the production of more rain roots.When differences in shoot volume were accounted for by allometry,small plants had relatively less shoot surface area and relativelymore root length per shoot volume than did large plants, whichmay be important for the water relations of seedling establishment. Agave deserti, Ferocactus acanthodes, allometry, desert succulents, root distribution, root length, seedling growth, seedling establishment, shoot surface area, shoot volume, water uptake