Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense.

Nematoda is a very species-rich phylum that has successfully adapted to almost all types of ecosystems. Despite their abundance and ecological importance, the taxonomic knowledge of nematodes is still limited and the identification of species is not trivial. In Cyatholaimidae, a relatively common and abundant family of free-living nematodes, the identification of organisms is challenging due to the overlap of some generic diagnoses and the absence of updated systematic reviews. Here we systematically reviewed the knowledge about the family diversity, providing a list of valid species, the diagnostic characters to genus level, and the geographical and habitat distribution of species. The review systematized a total of 619 records. The occurrences were classified into biogeographic ecoregions and habitats. Cyatholaimidae includes 211 valid species, classified in 20 genera. The genera can be differentiated based on six diagnostics characters, namely: pattern of cuticle ornamentation; number of longitudinal rows of pore-complex in cuticle; structures of the buccal cavity; presence/absence of pharyngeal bulb; pre-cloacal supplements aspect; and the shape of gubernaculum. Cyatholaimidae includes mainly marine species, mostly occurring in the Coastal Zone. Four and three species were registered in freshwater and terrestrial habitats, respectively, all classified in the genus Paracyatholaimus. About 38% of the valid species occur in more than one type of habitat, under very different environmental conditions, suggesting a broad niche. The occurrence of congeneric species in different habitats types indicates that, throughout the evolutionary history of the family, multiple ecological shift events have occurred. The family occurs worldwide in 74 ecoregions, and the majority of the records and species are in the North Sea and Western Mediterranean. Most species are endemic to one ecoregion, and examples of broadly distributed ones may be a result of misidentifications or cases of long-distance dispersal, especially for those associated with biological substrates.

Chromadoridae is a widespread family of mostly free-living marine nematodes. This systematic review provides for each genus: a historical background, an updated diagnosis and a list of species. Our review recognizes 37 valid genera, 395 valid species, 57 descriptions without enough morphological information for accurate identification (species inquirenda) and 10 species incerta sedis. We also recognize 21 species as nomena nuda. Additionally, polytomous keys were constructed for the subfamilies and for the genera of the three major subfamilies (Chromadorinae, Euchromadorinae and Hypodontolaiminae) using the most important diagnostic characters. A phylogenetic analysis based on rDNA sequences of species available in the GenBank was also conducted. Phylogenetic trees based on the 18S and 28S rDNA confirmed the classification into three subfamilies (Spilipherinae, Hypodontolaiminae and Chromadorinae), despite the absence of defined synapomorphies. Phylogenetic relationships at lower taxonomic level are problematic given the large number of sequences not identified to species level.

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Species descriptions of the family Xyalidae, as well as of most marine nematodes, were in general largely made in the past century (e.g. Allgén, 1927; Cobb, 1920; Gerlach, 1957; Lorenzen, 1977). Many of these descriptions were based on one or two specimens or even on juveniles with relatively few features of taxonomic value. Lack of types and inaccuracy in sampling localities are other problems associated with taxonomy of marine nematodes. These issues, together with the fact that in the past researchers had slower exchange of information and reduced access to some journals, led to the multiplication of synonyms. To propose a new species of nematode, particularly within a genus with a convoluted historical background, requires caution and critical taxonomical review prior to the description (Adams, 2001; Fonseca & Decraemer, 2008).

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