Blastocrithidia triatomae n. sp. Found in Triatoma infestans from Argentina

SYNOPSIS. Blastocrithidia triatomae n. sp. found in the digestive tract of T. infestans in Argentina is described. Cysts attached to the flagellum, a conspicuous characteristic of the new species, are described and shown in photomicrographs. Since T. infestans may harbor both T. cruzi and B. triatomae, or either one independently, it is essential that they be distinguished in xenodiagnosis.     

Do all Blackcaps Sylvia atricapilla show winter site fidelity?

Fidelity to previous wintering areas (i.e. site fidelity) has important ecological and evolutionary implications. However, since the percentage of recaptures of ringed birds at the same wintering area in subsequent years does not allow the estimation of the proportion of birds alive that exhibit site fidelity, previous studies on different passerine species have failed to show the true extent of this site fidelity. Here we use a recent approach, based on the comparison of survival rate estimates from capture-recapture data at single field stations with recovery data from a much larger area. The idea is to determine the proportion of birds still alive that return to the area. The study was carried out on the Blackcap Sylvia atricapilla , comparing the capture-recapture data of two field stations (Pilas [SW] and Tiana [NE]) situated 1000 km apart in Spain with the complete winter recovery data of the Spanish Ringing Office. Totals of 1936 and 3976 Blackcaps were ringed at Pilas (1981–1986) and Tiana (1975–1986), respectively, and the numbers of recaptures in subsequent winters were 94 and 34. The pooled annual survival rate estimation based on the two sites is 0.40 (s.e. = 0.05). The annual survival rate estimated from the Spanish ringing recovery data was 0.48 (s.e. = 0.08), which is not significantly different. We can conclude, therefore, that migrant Blackcaps in Spain, if alive, tend to return year after year to the previous wintering site.     

Palynology of South Indian Zingiberaceae

MANGALY, J. K. & NAYAR, J. 1990. Palynology of South Indian Zingiberaceae. Light microscope studies on pollen morphology of 21 Old World, tropical taxa of Zingiberaceae reveal that an exine is absent only in Kaempferia . A discontinuous exine layer consisting of circular plates joined together at margins occurs in Alpinia galanga and Amomum hypoleucum while all other taxa possess an uninterrupted exine layer which is commonly 0.7 μm to less than 2.0 μrn thick (3.2 μm in Zingiber zerumbet , 2.5 μm in Amomum hypoleucum ). Exine is spinose in Alpinia (smooth in Alpinia sanderae ), Amomum and Boesenbergia , verrucose in Eleltaria , tuberculate to areolate or striate in Zingiber , papillose in Globba and smooth or nearly so in Curcuma, Costus and Hedychiurn . Pollen grains are spheroidal, 50–90 μm in size (35 μm in Globba ophioglossa ), and inaparturate (foraminate in Costus ), except in Curcuma and Zingiber where they are ovoid to ellipsoidal, 70–135 times 60–80 μm in size and sulcate. A lamellated intine, much thicker than the exine, occurs in all, and it is thinner at the apertural region in Curcuma, Costus and Zingiber; in Elettaria and Hedychiurn it is thinner in one or few large scattered circular areas, and in Boesenbergia and Alpinia zerumbet on one side of the grains. Palynologirally Alpinia, Amomum, Boesenbergia, Kaempferia and Zingiber constitute one group while Elettaria, Hedychiurn and Costus constitute another.     

Polyamine Content Related to Seed Storage Performance in Zea mays

As part of a search for biochemical indicators of seed withgood survival characteristics during storage, polyamine (PA)levels were measured in embryos for Zea mays seeds. PA levelswere determined in individual embryos of Mean Generation Analysis(MGA) of crosses between lines which show good (C²) and poor(C⁶) storage characteristics. A correlation was found betweenhigher PA contents (putrescine and spermidine) and superiorsurvival characteristics within the populations that were analysedby MGA. Titres of putrescine (PUT) and spermidine (SPD) showedthat three-quarters of the F² resembled the C² parent and aquarter resembled the C⁶ parent. Furthermore, the backcrossC⁶F¹ showed that half of the embryos had PUT levels above theparental C⁶ line. A maternal inheritance effect was not observed.Neither spermine nor cadaverine content was correlated withthe survival inheritance pattern. Given the survival kineticsobtained, it is suggested that both the PA titres and the seedsurvival characteristics are determined by nuclear dominantfactors. Key words: Polyamines, Zea mays, seeds     

Can a sponge feeder be a herbivore? Tylodina perversa (Gastropoda) feeding on Aplysina aerophoba (Demospongiae)

Feeding biology in mollusks has important biological, ecological and evolutionary implications because many of the characteristics we observe in mollusks arise from their co-evolution with diet organisms. We investigated the relationship between the opisthobranch Tylodina perversa and the sponges Aplysina aerophoba and Aplysina cavernicola in order to ascertain the trophic interactions between them. The opisthobranch preferred specimens of Aplysina aerophoba inhabiting shallow overdeep waters, ectosome of Aplysina aerophoba over choanosome, and showed no preference for Aplysina cavernicola . The sponge Aplysina cavernicola lacks the cyanobacteria abundant in the ectosome of Aplysina aerophoba . Our study shows that the opisthobranch Tylodina perversa actively selects for sponges or sponge zones with high concentration of cyanobacteria, i.e. only a fraction of the ingested material is of animal origin. Addition of cyanobacteria to symbiont-free sponge material induced a shift in mollusk preference. Our results cast doubt over the widely recognized qualification of Tylodina perversa as a carnivorous sponge feeder and show evidence that cyanobacteria determine the opisthobranch food selection. Whether this is an isolated example of how symbionts may determine trophic interactions between hosts and predators or it is widespread in benthic organisms remains an open question that requires further investigation.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 429–438.     

SELECTION OF ASSESSORS BASED ON THEIR SKILL IN IDENTIFYING BASIC TASTES IN LOW CONCENTRATION SOLUTIONS

A method for the first step in the selection of trained sensory assessors, based on their skill in identifying basic tastes in low concentration solutions, was defined and evaluated. The solutions used were: 0.4 and 0.8% sucrose; 0.03, 0.04 and 0.06% citric acid; 0.08 and 0.15% sodium chloride; 0.02 and 0.03% caffeine. Concentration ranges were found adequate. The criterion for selection was to have over 65% correct answers. Out of 226 candidates who received the test, 141 (62%) were selected. The probability of a candidate having more than a certain percentage of correct answers was calculated. The influence of the dilution water quality on the perception of basic tastes was significant; distilled water was the most adequate.     

Role of ants in structuring the aphid community on apple

1. The aphids Dysaphis plantaginea Passerini, Aphis spp. (Aphis pomi De Geer and Aphis spiraecola Patch), and Eriosoma lanigerum Hausmann are commonly found together in apple orchards. Ants establish a mutualistic relationship with the myrmecophilous aphids D. plantaginea and Aphis spp. but not with E. lanigerum. 2. Field surveys and one experiment manipulating the presence of ants and the aphid species were conducted to test the hypothesis that ants play a role in structuring the community of these aphids on apple. 3. Ants tended D. plantaginea and Aphis spp. but not E. lanigerum colonies. In the field, D. plantaginea performed better in the presence of ants while no effect was observed in Aphis spp. Contrarily, populations of Aphis spp. in the manipulative experiment performed better in the presence of ants while no differences were observed for D. plantaginea. Such differences between field and manipulative conditions could be related to thermal tolerance, phenology, and life cycles. In contrast, populations of E. lanigerum were reduced in the presence of ants. 4. Ants also had a significant negative effect on the abundance of natural enemies, which could partially explain the benefits to the tended aphids. However, while ants did not provide a benefit to Aphis spp. when it was reared alone, in the presence of other species ant attendance increased Aphis abundance by 256% and simultaneously reduced E. lanigerum abundance by 63%. Therefore, ants benefited Aphis by reducing competition with other aphid species, which involves a different mechanism, explaining the benefit of ant attendance. Considering all the aphid species together, ants had a net positive effect on aphid abundance, which was consequently considered harmful for the plant. 5. Our results highlighted the role that ants play in structuring apple aphid communities and give support to the observed pattern that ants can benefit tended aphids while simultaneously reducing the abundance of untended herbivores.     

Light limitations to algal growth in tropical ecosystems

1. Spatial and temporal variations in algal concentrations are controlled in many aquatic ecosystems by the availability of solar irradiance, rather that nutrients or grazing. In such light limiting conditions, changes in the optical or hydrological characteristics of the water column will directly impact biomass concentrations. Here we develop and test an approach based on the relationship between available solar irradiance within the mixed layer and algal biomass concentrations. 2. As with most nutrient/biomass relationships, an increase in available solar energy favours an increase in biomass when light limitation prevails. The ratio between light/biomass is then used to determine a critical light requirement that can be used to estimate critical depth and compensation irradiance and open the way to exploring how changes in mixing depth and vertical attenuation may influence algal biomass concentrations. 3. This approach is used to describe real conditions in two disparate algal communities; the phytoplankton community in Lake Victoria, East Africa and the microphytobenthos community in the lacustrine system of Esteros del Iberá (South America). 4. Differences in the critical light requirement were used to examine the relative efficiency of the algal communities in their use of available solar energy. The tropical phytoplankton community showed similar energetic requirements to theoretical estimates and were found to be less efficient when compared with the phytobenthos community.     

Mitochondrial DNA diversity and taxa delineation in the land snails of the Iberus gualtieranus (Pulmonata,Helicidae) complex

Iberus gualtieranus is a species complex of land snails that is endemic to the Iberian Peninsula. The species taxonomy of the group is based merely on the basis of shell morphology, but validity of the existing taxonomy is uncertain. Using mitochondrial DNA (mtDNA) data (cytochrome oxidase I and 16S rRNA sequences) we were able to validate the observed phylogenetic taxa within the I. gualtieranus s.l. complex by means of the analysis of specimens of the different morphospecies, together with the study of topotypes. Strong incongruences were obtained between morphology and molecular data. The Iberus alonensis morphospecies comprised several genetically divergent but morphologically cryptic lineages. Considering (1) the allopatric distribution of the operational taxonomic units (OTUs), (2) the morphological differentiation, (3) the possible occurrence of hybridization among the different lineages, and (4) the strong differentiation of the mtDNA phylogroups, we suggest the main lineages obtained, for the time being, may be treated as evolutionary species. The robust phylogenetic reconstruction obtained allows us to consider I. alonensis s.s., Iberus campesinus, Iberus carthaginiensis, and Iberus gualtieranus s.s. as valid species. Two additional unnominated taxa of the alonensis shell type have also been identified. Further subdivisions are also considered, including Iberus gualtieranus mariae and Iberus gualtieranus ornatissimus. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 722–737.