Diversification and Species Boundaries of Rhinebothrium (Cestoda; Rhinebothriidea) in South American Freshwater Stingrays (Batoidea; Potamotrygonidae)

Background: Neotropical freshwater stingrays (Batoidea: Potamotrygonidae) host a diverse parasite fauna, including cestodes. Both cestodes and their stingray hosts are marine-derived, but the taxonomy of this host/parasite system is poorly understood. Methodology: Morphological and molecular (Cytochrome oxidase I) data were used to investigate diversity in freshwater lineages of the cestode genus Rhinebothrium Linton, 1890. Results were based on a phylogenetic hypothesis for 74 COI sequences and morphological analysis of over 400 specimens. Cestodes studied were obtained from 888 individual potamotrygonids, representing 14 recognized and 18 potentially undescribed species from most river systems of South America. Results: Morphological species boundaries were based mainly on microthrix characters observed with scanning electron microscopy, and were supported by COI data. Four species were recognized, including two redescribed (Rhinebothrium copianullum and R. paratrygoni), and two newly described (R. brooksi n. sp. and R. fulbrighti n. sp.). Rhinebothrium paranaensis Menoret & Ivanov, 2009 is considered a junior synonym of R. paratrygoni because the morphological features of the two species overlap substantially. The diagnosis of Rhinebothrium Linton, 1890 is emended to accommodate the presence of marginal longitudinal septa observed in R. copianullum and R. brooksi n. sp. Patterns of host specificity and distribution ranged from use of few host species in few river basins, to use of as many as eight host species in multiple river basins. Significance: The level of intra-specific morphological variation observed in features such as total length and number of proglottids is unparalleled among other elasmobranch cestodes. This is attributed to the large representation of host and biogeographical samples. It is unclear whether the intra-specific morphological variation observed is unique to this freshwater system. Nonetheless, caution is urged when using morphological discontinuities to delimit elasmobranch cestode species because the amount of variation encountered is highly dependent on sample size and/or biogeographical representation.

Evaluating the Taxonomic Identity in Four Species of the Lobose Testate Amoebae Genus Arcella Ehrenberg, 1832

The taxonomic identity in microbial eukaryotes remains an impediment to discussing ecology, biogeography and phylogeny, mainly due to a lack of standards in organism descriptions and few comparative works. The lobose testate amoebae (Arcellinida) present an ideal study system, as progress is severely hindered due to taxonomic confusion. In the present survey, we have examined the morphology, biometry and ecology of 2400 individuals in the genus Arcella Ehrenberg, 1832, collected from the Tiete River in Sao Paulo, Brazil. We then contrasted these new data with 26 previously described species, varieties and forms, looking for consistencies and trying to establish distinct entities. Using a combination of morphology and multivariate statistics we were able to determine 4 distinct taxa (Arcella hemisphaerica, Arcella discoides, Arcella gibbosa and Arcella brasiliensis), each of them encompassing a number of other non-distinct nominal taxa. We describe in detail each of the 4 taxa with notes on ecology and biogeography, and list the indistinguishable names in an effort to make identification and taxonomy in the testate amoebae a more objective and precise exercise by clarifying the taxonomic identity.

Description and Phylogenetic Relationships of a New Genus and Species of Lizard (Squamata, Gymnophthalmidae) from the Amazonian Rainforest of Northern Brazil

Marinussaurus curupira, a new genus and species of Gymnophthalmidae lizard is described from Iranduba, state of Amazonas, Brazil. The genus is characterized by an elongate body; short and stout pentadactyl limbs; all digits clawed; single frontonasal; two prefrontals; absence of frontoparietals; interparietal and parietals forming a straight posterior margin, with interparietal shorter than parietals; distinctive ear opening and eyelid; few temporals; three pairs of chin shields; nasal divided; a distinct collar; smooth, mainly hexagonal, dorsal scales; smooth quadrangular ventral scales; two precloacal and three femoral pores on each side in males; pores between three or four scales. Parsimony (PAR) and partitioned Bayesian (BA) phylogenetic analyses with morphological and molecular data recovered the new genus as a member of the Ecpleopodini radiation of the Cercosaurinae. A close relationship of the new genus with Arthrosaura is postulated.

Beyond the Fragmentation Threshold Hypothesis: Regime Shifts in Biodiversity Across Fragmented Landscapes

Ecological systems are vulnerable to irreversible change when key system properties are pushed over thresholds, resulting in the loss of resilience and the precipitation of a regime shift. Perhaps the most important of such properties in human-modified landscapes is the total amount of remnant native vegetation. In a seminal study Andren proposed the existence of a fragmentation threshold in the total amount of remnant vegetation, below which landscape-scale connectivity is eroded and local species richness and abundance become dependent on patch size. Despite the fact that species patch-area effects have been a mainstay of conservation science there has yet to be a robust empirical evaluation of this hypothesis. Here we present and test a new conceptual model describing the mechanisms and consequences of biodiversity change in fragmented landscapes, identifying the fragmentation threshold as a first step in a positive feedback mechanism that has the capacity to impair ecological resilience, and drive a regime shift in biodiversity. The model considers that local extinction risk is defined by patch size, and immigration rates by landscape vegetation cover, and that the recovery from local species losses depends upon the landscape species pool. Using a unique dataset on the distribution of non-volant small mammals across replicate landscapes in the Atlantic forest of Brazil, we found strong evidence for our model predictions - that patch-area effects are evident only at intermediate levels of total forest cover, where landscape diversity is still high and opportunities for enhancing biodiversity through local management are greatest. Furthermore, high levels of forest loss can push native biota through an extinction filter, and result in the abrupt, landscape-wide loss of forest-specialist taxa, ecological resilience and management effectiveness. The proposed model links hitherto distinct theoretical approaches within a single framework, providing a powerful tool for analysing the potential effectiveness of management interventions.

A New Species of Riama from Ecuador Previously Referred to as Riama hyposticta (Boulenger, 1902) (Squamata: Gymnophthalmidae)

We describe Riama crypta, new species, from the western slopes of the Cordillera Occidental, Ecuador. This taxon was formerly referred to as Riama hyposticta, a rare species described on the basis of an adult male from northern Ecuador and here recorded from southwestern Colombia. The new species differs principally from Riama hyposticta by an incomplete superciliary series, formed just by the anteriormost superciliary scale (superciliary series complete in R. hyposticta, formed by five or six scales), no nasoloreal suture [= loreal absent] (complete (= loreal present] in R. hyposticta), distinct dorsolateral stripes at least anteriorly (scattered brown spots dorsally without dorsolateral stripes in R. hyposticta), and ventral coloration composed of small cream or brown spots or longitudinal stripes (dark brown with conspicuous transverse white bars and spots). Additionally, we document the presence of distal filiform appendages on the hemipenial lobes of both species.

Matelea quindecimlobata (Apocynaceae, Asclepiadoideae), a New Species from Amazonas, Brazil

Matelea quindecimlobata Farinaccio & W. D. Stevens, a new species of Asclepiadoideae, Apocynaceae, from Amazonas, Brazil, is described and illustrated. The most diagnostic aspect of this new species of Matelea. Aublet s. str. is the lobed, then fimbriate outer margin of the outer corona.

Actinocephalus koernickeanus, a New Species of Eriocaulaceae from Minas Gerais, Brazil

We describe and illustrate the new species Actinocephalus koernickeanus Trovo & F. N. Costa (Eriocaulaceae, Paepalanthoideae) from the Espinhaco Range in Minas Gerais, Brazil, and compare it with the morphologically similar species, Paepalanthus actinocephaloides Silveira and P. barbiger Silveira, both from Espinhaco Range.

Croton rufolepidotus (Euphorbiaceae s. str.), a New Species from Antioquia, Colombia

Crown rufolepidotus Caruzo & Riina (Euphorbiaceae s. str.), a new species from Colombia, is here described and illustrated. The new species is endemic to an area of lowland secondary forests in Antioquia. Morphological characters indicate that this species belongs to Croton sect. Cleodora (Klotzsch) Baill. due to its arborescent habit, petiolar glands, 15 to 25 stamens, as well as the pistillate flowers with imbricate sepals and multifid styles.

Systematic Revision of the granulatus Group of Urophonius Pocock, 1893 (Scorpiones, Bothriuridae), with Description of a New Species from Central Chile

A systematic revision of the granulatus group of the bothriurid scorpion genus Urophonius Pocock, 1893 is presented. Urophonius pizarroi, n. sp., a new species from central Chile, is described. Urophonius granulatus Pocock, 1898, Urophonius somuncura Acosta, 2003, and Urophonius tregualemuensis Cekalovic, 1981, are redescribed using modern standards. The adult males of U. somuncura and U. tregualemuensis are described for the first time. A distribution map and key to the species of the granulatus group are provided, along with a discussion of their phenology.

Normal and defective mariner-like elements in Rhynchosciara species (Sciaridae, Diptera)

Mariner-like elements are widely present in diverse organisms. These elements constitute a large fraction of the eukaryotic genome; they transpose by a ""cut-and-paste"" mechanism with their own transposase protein. We found two groups of mobile elements in the genus Rhynchosciara. PCR using primers designed from R. americana transposons (Ramar1 and Ramar2) were the starting point for this comparative study. Genomic DNA templates of four species: R. hollaenderi, R. millerii, R. baschanti, and Rhynchosciara sp were used and genomic sequences were amplified, sequenced and the molecular structures of the elements characterized as being putative mariner-like elements. The first group included the putative full-length elements. The second group was composed of defective mariner elements that contain a deletion overlapping most of the internal region of the transposase open reading frame. They were named Rmar1 (type 1) and Rmar2 (type 2), respectively. Many conserved amino acid blocks were identified, as well as a specific D,D(34) D signature motif that was defective in some elements. Based on predicted transposase sequences, these elements encode truncated proteins and are phylogenetically very close to mariner-like elements of the mauritiana subfamily. The inverted terminal repeat sequences that flanked the mariner-like elements are responsible for their mobility. These inverted terminal repeat sequences were identified by inverse PCR.