CHEMOTAXIS IN THE NUDIBRANCH HERMISSENDA CRASSICORNIS: DOES INGESTIVE CONDITIONING INFLUENCE ITS BEHAVIOUR IN A Y-MAZE?

The nudibranch mollusc Hermissenda crassicornis can be culturedeasily in the laboratory and has been used as a biomedical modelfor learning and memory studies. Cultured animals whose onlyprey was Tubu-laria crocea were tested for responses to otherprey. Naive slugs were conditioned with six different dietsand tested for behaviour in a Y-maze. H. crassicornis was ableto detect chemotactically food items which it had never beenin contact with (such as Pennaria), but it did not detect someof the conditioning diets (e.g. Metridium). At least three hydroidspecies induce a chemotactic behaviour in the slug. It is shownthat ingestive conditioning does affect their response in single-choiceand double-choice experiments. As food items other than cnidariansare also detected, it is likely that different kairomones areresponsible for the nudibranch's behaviours. ^*Present address: Centre d'Estudis Avançats de Blanes,C.S.I.C., Cami de Sta. Bárbara s/n. 17300 Blances (Girona)Spain. (Received 10 March 1997; accepted 25 June 1997)     

Molecular dating and diversification of the South American lizard genus Liolaemus (subgenus Eulaemus) based on nuclear and mitochondrial DNA sequences

The temperate South American lizard genus Liolaemus is the one of the most widely distributed and species‐rich genera of lizards on earth. The genus is divided into two subgenera, Liolaemus sensu stricto (the ‘Chilean group’) and Eulaemus (the ‘Argentino group’), a division that is supported by recent molecular and morphological data. Owing to a lack of reliable fossil data, previous studies have been forced to use either global molecular clocks, a standardized mutation rate adopted from previous studies, or the use of geological events as calibration points. However, simulations indicate that these types of assumptions may result in less accurate estimates of divergence times when clock‐like models or mutation rates are violated. We used a multilocus data set combined with a newly described fossil to provide the first calibrated phylogeny for the crown groups of the clade Eulaemus, and derive new fossil‐calibrated substitution rates (with error) of both nuclear and mtDNA gene regions for Eulaemus specifically. Divergence date estimates for each of the crown groups and appropriate rate estimates will provide the foundation for understanding rates of speciation, historical biogeography, and phylogeographical history for various clades in one of the most diverse lizard genera in the poorly studied Patagonian region. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 825–835.     

Acid and Neutral Hydrolases in Trypanosoma cruzi. Characterization and Assay*

Twelve acid hydrolases, 4 near-neutral hydrolases and alkaline phosphatase were demonstrated in 0.34 M sucrose homogenates of Trypanosoma cruzi strain Y: p-nitrophenylphosphatase and α-naphthylphosphatase, with optimum pH at ? 6.0; α-galactosidase, β-galactosidase, β-glucosidase, N-acetyl-β-glucosaminidase, cathepsin A and peptidase I and III, with optimum pH between 5.0 and 6.0: and arylsulfatase cathepsin D, α-arabinase and α-mannosidase with optimum pH at ? 4.0 α-Glucosidase, gluccse-6-phosphatase and peptidase II had optimum pH at ? 7.0. β-Glycerophcsphatase had a broad pH-activity curve from 4.0 to 7.4, with maximum activity at pH 7.0. The main kinetic characteristics of these enzymes and their quantitative assay methods were studied. No activity was detected for α-fucosidase, β-xylosidase, β-glucuronidase, elaidate esterase. acid lipase, and alkaline phospho-diesterase.     

PHYLLODESMIUM GUAMENSIS (NUDIBRANCHIA: AEOLIDOIDEA), A NEW SPECIES FROM GUAM(MICRONESIA)

A new species of Phyllodesmium (Aeolidoidea) from Guam (Micronesia)is described. Phyllodesmium guamensis n.sp. is characterizedby having two rows of denticles in the radular teeth, this beingdifferent from the previously described species of the genus.The shape of the teeth, however, is identical in all the speciesof the genus, and unique among aeolids. Furthermore, P. guamensispossesses a double row of cerata in the precardiac cluster andup to 10 post-cardiac ceratal rows. Also, P. guamensis showsa very dense accumulation of zooxanthellae in the ceratal digestivegland, which is ramified inside the cerata. This species feedson at least three species of the soft coral Sinularia: S. polydactyla,S. maxima and a third, undescribed species. The aeolid matchesthe colour of its prey and is cryptic on the soft coral surface. (Received 3 October 1996; accepted 28 April 1997)     

Congeneric phylogeography: hypothesizing species limits and evolutionary processes in Patagonian lizards of the Liolaemus boulengeri group (Squamata: Liolaemini)

In poorly known groups for which data are insufficient to develop biologically plausible model‐based approaches to phylogeographical analyses, a ‘first hypotheses’ protocol is suggested as offering the best way to generate hypotheses for subsequent model‐based tests. Preliminary hypotheses are formulated about species boundaries and population processes in three species complexes of the Liolaemus boulengeri group in the context of mtDNA ‘congeneric phylogeography’. The temperate South American Liolaemus provides a model with ancient and recent allopatric divergence across ecologically and geologically complex landscapes, incipient speciation, secondary contact, and discordance between molecular and morphological patterns of variation. Moderately dense sampling of widely distributed ‘inertial’ species in the Patagonian Steppe has revealed hidden genetic and probably species diversity, and also hinted at demographic and historical processes that may have shaped the histories of these taxa. Five of the seven focal species of the present study were paraphyletic for mtDNA genealogies, suggesting that they represent complexes of species, and nested clade phylogeographical analysis (NCPA) analyses suggest that different historical and demographic processes have shaped the observed patterns. Introgression and incomplete lineage sorting are hypothesized as being the cause of some of the observed paraphyly. Provisional delimitations of species are proposed and NCPA is used to generate hypotheses of population history, all of which are subject to further testing. Multi‐faceted studies, involving phylogenetic assessments of independent molecular markers and morphological variation across codistributed taxa with estimates of niche breadths in a landscape context, will likely yield the most promising returns for cross‐validation of hypotheses of population and speciation histories. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89 , 241–275.     

REVIEW OF THE GENUS DENDRODORIS EHRENBERG, 1831 (GASTROPODA: NUDIBRANCHIA) IN THE ATLANTIC OCEAN

Six valid species of the nudibranch genus Dendrodons Ehrenberg,1831 inhabit the Atlantic Ocean, including the Mediterraneanand Caribbean Seas. Dendrodons lumbata (Cuvier, 1804), Dendrodonsgrandiflora (Rapp, 1827), Dendrodons nigra (Stimpson, 1855)(immigrant from the Red Sea), Dendrodons krebsu (Mörch,1863), Dendrodoru senegalensis Bouchet, 1975 and Dendrodonswarta Marcus & Gallagher, 1976. Additional data about thebiology and geographical distribution of these species are presented.New evidence suggests that other species assigned to the genusDendrodons, Dendrodons racemosa Pruvot-Fol, 1951 and Dendrodonsminima Pruvot-Fol, 1951, must be included in the genus DoriopsillaBergh, 1880. Three new species of Dendrodoris are describedfrom the Northeastern Atlantic and West Africa;Dendrodons angolensis,Dendrodoris guineana and Dendrodons herytra. The variable external morphology makes species recognition difficult.Instead, the diagnostic characters utilised to separate speciesare the shape of the male cirrus hooks, the structure of thereproductive system and features of the egg-mass. (Received 25 April 1995; accepted 1 August 1995)     

THE GROWTH OF PELTODORIS ATROMACULATA BERGH, 1880 (GASTROPODA: NUDIBRANCHIA) IN THE LABORATORY

The growth of Peltodons atromaculata Bergh, 1880, measured astotal dorsal body area, was followed in the laboratory for 15months. The growth of dorsal brown patches was compared to thetotal area of the mantle, and was shown to be approximatelyconstant over time in the different animals. This numericalapproach can be useful to quantify the body pigmentation clinepreviously described for Mediterranean specimens. P atromaculatahas an annual life-cycle in the laboratory, reaching its maximumsize before opposition. Post-spawning mortality followed a decreasein size for all specimens. Mantle margin autotoray in P atromaculataseems not to be related to defence against predation, but itis a process that takes place before death in laboratory. (Received 1 December 1994; accepted 28 April 1995)