Muhlenhardt-Siegel U.,Biozentrum Grindel
Marine Biodiversity | Year: 2015
Two known and two new species, as well as two new genera from the deep sea of the south-western Atlantic, Cape Basin and the Weddell Sea are described, including Leptostyloides secundus n. sp. and Pseudoleptostyloides mediosetosus n. gen. and n. sp. The diagnosis of the genera Divacuma and Leptostyloides are improved, the species Makrokylindrus paradivacumatus is transferred to the new genus Austrostylis, and the species Leptostyoides longiappendiculata is transferred to Pseudoleptostyloides n. gen. © 2014, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg.
Haas A.,Biozentrum Grindel |
Das I.,University Malaysia Sarawak
Bonner Zoologische Monographien | Year: 2011
Our ad hoc survey of 130 books and monographs showed that almost 70% did not present any descriptive information on larval anurans, and when larval stages were included the quality of documentation often tended to be poor. The larval (or developmental) stages of 51 species of east Malaysian frogs still remain unknown. Modern methods and techniques have changed the way we treat larvae taxonomically, and we recommend their adoption in tadpole research. Notably, DNA barcoding allows for unequivocal matching with adult frogs, and digital color photography provides documentation of tadpole features of unprecedented quality, partly replacing traditional drawings. Both techniques are considered essential for the study of tadpoles. Tadpole measurements have now reached a high level of standardization and can be performed quickly, accurately, and easily with digital microscopes. Nevertheless, line drawings and SEM may still be valuable techniques when certain details need to be demonstrated.
Natalia A.,University of Buenos Aires |
Muhlenhardt-Siegel U.,Biozentrum Grindel
Zootaxa | Year: 2010
Two new deep-sea cumaceans, Diastylis andeepae and D. catalinae are described from the Weddell Sea. Diastylis andeepae n. sp. can be distinguished from other members of the genus by a combination of characters including: carapace with small tubercles all over and anterior part with an arched row of teeth extending from each side of the pseudorostrum and disappearing a short distance before reaching the inferior margin of the carapace, ischium of the pereopod 2 with four strong teeth, endopod uropod of two articles. Diastylis catalinae n. sp. is a closely related species to D. richardi Fage 1929 recorded from the Bay of Biscay, however D. catalinae can be easily separated from D. richardi by having: (1) on each side of the anterior part of the carapace several teeth arranged in two non-uniform rows (randomly distributed and with two antero-lateral horns in D. richardi); (2) clearly visible pereonites 1 and 2 in dorsal view (hardly visible in D. richardi); (3) one tooth on each postero-lateral angle of the pereonite 5 (without teeth in D.richardi); and (4) one minute simple seta on article 4 of the antenna 2 (a long setulate seta in D. richardi). Copyright © 2010 Magnolia Press.
Agrawal A.A.,Cornell University |
Petschenka G.,Biozentrum Grindel |
Bingham R.A.,Colorado College |
Weber M.G.,Cornell University |
Rasmann S.,University of Lausanne
New Phytologist | Year: 2012
Contents: Summary 28 I. Historic background and introduction 29 II. Diversity of cardenolide forms 29 III. Biosynthesis 30 IV. Cardenolide variation among plant parts 31 V. Phylogenetic distribution of cardenolides 32 VI. Geographic distribution of cardenolides 34 VII. Ecological genetics of cardenolide production 34 VIII. Environmental regulation of cardenolide production 34 IX. Biotic induction of cardenolides 36 X. Mode of action and toxicity of cardenolides 38 XI. Direct and indirect effects of cardenolides on specialist and generalist insect herbivores 39 XII. Cardenolides and insect oviposition 39 XIII. Target site insensitivity 40 XIV. Alternative mechanisms of cardenolide resistance 40 XV. Cardenolide sequestration 41 Acknowledgements 42 References 42 Summary: Cardenolides are remarkable steroidal toxins that have become model systems, critical in the development of theories for chemical ecology and coevolution. Because cardenolides inhibit the ubiquitous and essential animal enzyme Na +/K +-ATPase, most insects that feed on cardenolide-containing plants are highly specialized. With a huge diversity of chemical forms, these secondary metabolites are sporadically distributed across 12 botanical families, but dominate the Apocynaceae where they are found in >30 genera. Studies over the past decade have demonstrated patterns in the distribution of cardenolides among plant organs, including all tissue types, and across broad geographic gradients within and across species. Cardenolide production has a genetic basis and is subject to natural selection by herbivores. In addition, there is strong evidence for phenotypic plasticity, with the biotic and abiotic environment predictably impacting cardenolide production. Mounting evidence indicates a high degree of specificity in herbivore-induced cardenolides in Asclepias. While herbivores of cardenolide-containing plants often sequester the toxins, are aposematic, and possess several physiological adaptations (including target site insensitivity), there is strong evidence that these specialists are nonetheless negatively impacted by cardenolides. While reviewing both the mechanisms and evolutionary ecology of cardenolide-mediated interactions, we advance novel hypotheses and suggest directions for future work. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.
Pankoke H.,Biozentrum Grindel |
Bowers M.D.,University of Colorado at Boulder |
Dobler S.,Biozentrum Grindel
Insect Biochemistry and Molecular Biology | Year: 2012
Herbivores with polyphagous feeding habits must cope with a diet that varies in quality. One of the most important sources of this variation in host plant suitability is plant secondary chemistry. We examined how feeding on plants containing one such group of compounds, the iridoid glycosides, might affect the growth and enzymatic activity in a polyphagous caterpillar that feeds on over 80 plant species in 50 different families. Larvae of the polyphagous arctiid, Grammia incorrupta, were reared exclusively on one of two plant species, one of which contains iridoid glycosides (Plantago lanceolata, Plantaginaceae) while the other does not (Taraxacum officinale, Asteraceae). Larval weight was measured on the two host plants, and midgut homogenates of last instar larvae were then assayed for activity and kinetic properties of β-glucosidases, using both a standard substrate, 4-nitrophenyl-β- d-glucose (NPβGlc), and the iridoid glycoside aucubin, one of the two main iridoid glycosides in P. lanceolata. Larvae feeding on P. lanceolata weighed significantly less and developed more slowly compared to larvae on T. officinale. While the larval midgut β-glucosidase activity determined with NPβGlc was significantly decreased when fed on P. lanceolata, aucubin was substantially hydrolyzed and the larval β-glucosidase activity towards both substrates correlated negatively with larval weight. Our results demonstrate that host plants containing high concentrations of iridoid glycosides have a negative impact on larval development of this generalist insect herbivore. This is most likely due to the hydrolysis of plant glycosides in the larval midgut which results in the release of toxic aglycones. Linking the reduced larval weight to the toxin-releasing action of an iridoid glycoside cleaving β-glucosidase, our results thus support the detoxification limitation hypothesis, suggesting fitness costs for the larvae feeding solely on P. lanceolata. Thus, in addition to the adaptive regulation of midgut β-glucosidase activity, host plant switching as a behavioral adaptation might be a prerequisite for generalist herbivores that allows them to circumvent the negative effects of plant secondary compounds. © 2012 Elsevier Ltd.