A growing body of evidence showing that individuals of some social species live in non-kin groups suggests kin selection is not required in all species for sociality to evolve. Here, we investigate 2 populations of Octodon degus , a widespread South American rodent that has been shown to form kin and non-kin groups. We quantified genetic relatedness among individuals in 23 social groups across 2 populations as well as social network parameters (association, strength, and clustering coefficient) in order to determine if these aspects of sociality were driven by kinship. Additionally, we analyzed social network parameters relative to ecological conditions at burrow systems used by groups, to determine if ecological characteristics within each population could explain variation in sociality. We found that genetic relatedness among individuals within social groups was not significantly higher than genetic relatedness among randomly selected individuals in both populations, suggesting that non-kin structure of groups is common in degus. In both populations, we found significant relationships between the habitat characteristics of burrow systems and the social network characteristics of individuals inhabiting those burrow systems. Our results suggest that degu sociality is non-kin based and that degu social networks are influenced by local conditions. Es creciente la evidencia que apoya la ocurrencia de especies sociales donde los individuos no están emparentados genéticamente, lo que sugiere que la selección de parentesco no es indispensable para la evolución de la sociabilidad. En este estudio se examinaron dos poblaciones de Octodon degus , un roedor sudamericano donde los grupos sociales pueden o no incluir individuos cercanamente emparentados. Se cuantificó el parentesco genético entre individuos en 23 grupos sociales y en redes sociales de dos poblaciones para determinar si estos aspectos de la sociabilidad dependen del grado de parentesco. Además, se examinaron asociaciones entre los parámetros cuantificados de las redes sociales (asociación, fuerza, coeficiente de anidamiento) y las condiciones ecológicas a nivel de los sistemas de madriguera usados por cada grupo. El grado de parentesco genético dentro de los grupos no fue distinto del grado de parentesco entre individuos de la población tomados al azar, lo que apoya que una estructura de grupos no emparentada es la regla en Octodon degus . En ambas poblaciones se registró una asociación entre características ecológicas de los sistemas de madriguera y atributos de las redes sociales de los individuos que usan estas estructuras. Nuestros resultados indican que la sociabilidad en Octodon degus no está basada en relaciones de parentesco y que las redes sociales de estos animales dependen de las condiciones ecológicas.

Fleas associated with small mammals from seven localities from northern and central Chile were assessed. We captured 352 small mammals belonging to 12 species from which we obtained 675 fleas belonging to 15 different species. The most frequently captured flea species were Neotyphloceras crassispina crassispina (n = 198) and N. chilensis (n = 175). High values of flea species richness and diversity were found in Fray Jorge National Park (NP), a north-central Chilean site, whereas the highest values of mean abundance (MA) and prevalence were found in three diverse sites that include Los Molles River, a high altitude site located in north-central Chile, Fray Jorge NP and Dichato, in south-central Chile. On the other hand, high values of flea richness and diversity were found on two rodent species, Abrothrix olivacea and A. longipilis, whereas the highest values of MA and prevalence were found on Oligoryzomys longicaudatus, A. longipilis and Phyllotis xanthopygus. A total of three new host recordings, nine new localities and nine new host species and locality recordings are reported. Also, this study represents the first known record of Tetrapsyllus (Tetrapsyllus) comis in Chile and the first ecological analysis of Neotyphloceras chilensis.

The male of Ixodes abrocomae Lahille, 1916 (Acari: Ixodidae) is redescribed and the female described for the first time from specimens collected on the rodents Abrothrix longipilis (Waterhouse), A. olivaceous (Waterhouse) and Phyllotis xanthopygus (Waterhouse) at Coquimbo, Chile. The males of I. abrocomae are peculiar in having the combination of the following features: length and width less than 2 mm and 1 mm, respectively; hypostome notched with two rows of stout denticles and several small internal denticles; article II of the palpi with two conspicuous dorsal setae; coxa I with two subequal spurs; coxae II-IV with a single spur plus an indication of a second spur; and a scutum with long, scattered hairs except for the glabrous postero-median field which reaches to the marginal fold. The females of I. abrocomae are peculiar in possessing a combination of: a pointed hypostome, with a 3/3 dentition of flared denticles; a long, narrow scutum with few 'hairs' and with punctations which are especially numerous in the posterior region; a triangular basis capituli, with oval porose areas lacking definitive borders and separated by the width of one area, and a sinuous posterior margin with small cornuae; one spur on coxae I-IV; and conspicuous setae on the interno-dorsal face of palpal article II and the ventral face of article I. Sequences of 16S rDNA were identical for male and female I. abrocomae, but differ by 3.8% and 5.5% from sequences of their closest relatives, I. stilesi Neumann, 1911 and I. sigelos Keirans, Clifford & Corwin, 1976, respectively. Characters enabling the separation of I. abrocomae from Ixodes spp. distributed in the southwestern Neotropics are presented. Records of I. abrocomae in different climatic areas and on different, widely distributed rodent hosts indicate that this species may be present beyond its known Chilean territorial range (Regions III and IV).

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