An undescribed rickettsia was directly analyzed with specific rickettsial molecular biology tools on Ixodes ricinus L. collected in different localities of the province of Cadiz (southwestern Spain). On the basis of the results of the citrate synthase (glta) gene, 190 kD-outer membrane protein (rOmpA) gene, and 16S ribosomal RNA (16S rRNA) gene partial sequence data, it was found that this rickettsia is sufficiently genetically distinct from other Rickettsia to be considered a distinct taxonomic entity. The isolation and culture of this organism, as well as comparative antigenic analysis, are required to ensure its conclusive taxonomic placement among spotted fever rickettsiae. The epidemiologic role of this new rickettsial agent and its possible pathogenicity to wild and domestic animals or humans is still unknown and needs to be investigated.

Communal nesting is generally assumed to be adaptive, meaning that it confers a fitness advantage on the individuals that share a nest site. This advantage may accrue directly to adults, or it may affect adult fitness through gains in offspring survival. In particular, survival of juveniles reared in communal groups may be greater because adults are present in the nest more often to provide care to young. To test the hypothesis that communal nesting is associated with increased adult presence in the nest, we used radiotelemetry to examine patterns of adult nest attendance as a function of group size for free-living colonial tuco-tucos (Ctenomys sociabilis). Burrow systems of this social, subterranean rodent are inhabited by 1-6 adult females and, in some cases, a single adult male. Data obtained from residents of 26 burrow systems monitored during 1996-2000 indicated that the percentage of time that the nest was unattended (no adult present) did not vary predictably with date or time of day during the period between the birth and weaning of young. The percentage of time that the nest was unattended, however, decreased significantly as the number of adults per burrow system increased. This difference was most evident when the percentage of time that the nest was unattended was compared for lone females versus multi-adult groups. We suggest that increased nest attendance has important implications for the survival of juveniles reared in multi-adult burrow systems but that this effect may be confounded by the fitness consequences of other costs and benefits associated with communal nesting in this species.

ABSTRACT. Ctenomys pearsoni (Pearson's tuco-tuco) is a subterranean rodent native to Uruguay. We tested the amplification pattern of 12 microsatellite loci, designed for C. sociabilis and C. haigi in a C. pearsoni population. DNA extractions were made from hair samples, and PCR amplification products were run on an ABI 3100 microcapillary gel. Eight loci were selected to form a highly polymorphic panel that could be used to efficiently screen populations of this species. In DNA from 35 tuco-tucos, the mean polymorphic information content value was 0.6536 and the mean expected heterozygosity was 0.7166. Paternity non-exclusion probabilities for seven independent loci were NE-1P = 0.0766 and NE-2P = 0.0108, and combined non-exclusion P(ID) was 6.2 x 10 -7 . This panel of microsatellite loci has sufficient power to make inferences regarding group structure, mating strategies and evolutionary relationships among populations.

Ctenomys is a genus of South American subterranean rodents that is distributed from Peru to southern Argentina and Uruguay. The present work studies the reproductive behavior (courtship and copula) of Ctenomys pearsoni (Carrasco population, Uruguay). To carry out the characterization, we used an ethogram with 19 behavioral units grouped into different categories. By studying 10 couples we quantified the frequency of occurrence and the time invested in each behavioral unit during the development of the interaction. Through the analysis of the results, the roles of each partner and the importance of each one's role in the development of reproductive behavior are inferred. The results obtained are compared with the data available for other populations of the species and other species of the genus. We discussed the relevance of classifying the reproductive pattern on the basis of the Dewsbury classification. Finally, the importance of each sex in the development and molding of reproductive behavior is discussed.