Morphological and molecular analyses confirm the presence of the newly described bat species Molossus melini in the Espinal ecoregion from Argentina.

Until now, Molossus melini was known only from its type locality, in the south of Santa Fe province, Argentina. Specimens of this species were collected in 2021 from a roost in a Fraxinus tree of the urban woodland of Paraná city, Entre Ríos province, Argentina. Bat identification was made by comparing external and cranial characters and measurements with those reported in the bibliography and corroborated by a phylogenetic analysis based on the cytochrome b gene. Also, multivariate morphometric analyses showed that cranial measurements, but not external ones, are informative enough to discriminate M. melini from the other Molossus species in Argentina (M. currentium, M. fluminensis, and M. molossus). This new record extends the distribution of M. melini from the south of Santa Fe province by 230 km to the northeast and represents the first record of the species in the Espinal ecoregion. Supplementary information: The online version contains supplementary material available at 10.1007/s13364-023-00679-1.

First detection of "Candidatus Rickettsia wissemanii" in Ornithodoros hasei (Schulze, 1935) (Acari: Argasidae) from Argentina.

The aim of this study was to assess the presence of Rickettsia in soft ticks (Acari: Argasidae) collected from insectivorous bats (Chiroptera) in Santa Fe province, Argentina. First, a subset of ticks were mounted in Hoyer's medium to be determined by morphological characters and then confirmed by sequencing the mitochondrial 16S rRNA gene. Also ticks were processed by PCR assays using primers CS-78 and CS-323, which amplify a fragment of the Rickettsia spp. gltA gene. Positive ticks were subjected to a second PCR round with primers Rr190.70p and Rr190.701n of the spotted fever group rickettsiae ompA gene. A phylogenetic analysis was performed with Maximum-likelihood method, and the best fitting substitution models were determined with the Akaike Information Criterion. Five bats of the species Eptesicus diminutus Osgood, 1915, Eptesicus furinalis (d'Orbigny and Gervais, 1847), Eptesicus spp. (Vespertilionidae), and Molossops temminckii Burmeister, 1854 (Molossidae) were parasitized with Ornithodoros hasei (Schulze, 1935) larvae. One E. diminutus ticks' tested positive to "Candidatus Rickettsia wissemanii", a spotted fever group rickettsiae. The association O. hasei -"Ca. R. wissemanii" detected in this study represents the first evidence of a Rickettsia in Ornithodoros ticks in Argentina and the third report of this association in America. Also, this finding constitutes the first record of "Ca. R. wissemanii" in Argentina. Finally, we found for the first time the insectivorous bats E. diminutus and E. furinalis parasitized with O. hasei larvae. These findings add two new hosts and a new location, the southernmost recorded to date, for O. hasei.

Social play among black and gold howler monkey (Alouatta caraya) immatures during intergroup encounters.

We studied intergroup social play (IGSP) among immatures in wild black and gold howler monkeys (Alouatta caraya) in northeastern Argentina. IGSP events are one form of affiliative interaction that can occur during intergroup encounters. The main goal of this study was to analyze IGSP in A. caraya immatures and assess how intrinsic (e.g., age and sex) and extrinsic (e.g., seasonality) factors can influence the development of this type of social behavior. We followed 12 groups between 2008 and 2015 and recorded 182 encounters and 61 events of IGSP. Considering the composition of play partners, most IGSP events occurred among juveniles of both sexes (33%), followed by juveniles that were only-male (31%), and finally between mixed-sex juveniles and infants (20%) interactions. Additionally, most IGSP events occurred mainly in summer (56%), followed by spring (29%), with fewer events occurring in autumn (15%) and no IGSP events recorded in winter. Our results suggest that IGSP constitutes a beneficial activity in wild A. caraya that promotes behavioral flexibility, where immatures acquire social skills, such as tolerance, by interacting with unknown individuals. Moreover, the higher participation of young males in IGSP is consistent with the fact that adult black and gold howler males tend to be more actively involved in group encounters than females, supporting the hypothesis that social play provides benefits in the development of motor and social skills. Finally, seasonality in the frequencies of IGSP might be related to availability of foods with high and easily mobilized energy content in summer and spring.

Sex differences in the behavior of wild Alouatta caraya infants.

Several primates show sex-based differences in activity patterns and social interactions during infancy. These differences have been associated with adult social and reproductive functions of males and females and are related to male-male competition. Our goal was to describe behavioral patterns of wild Alouatta caraya male and female infants, a species with sexual dimorphism in body size and behavioral strategies during adulthood. We also examined the relationship between life history variables, infant sex and age, activity patterns, and social interactions in order to determine whether males and females follow different trajectories during early growth. Over a 27-month study, we observed 21 male infants and 14 female infants across two similar sites in northern Argentina. Data were analyzed using generalized linear mixed model (GLMM) tests. We found no differences in suckling time or weaning age between males and females (9.7 vs. 9.4 months), but male infants spent more time feeding on solid food and resting than female infants. Males also invested more time in contact with their mothers than did female infants, and mothers rejected and broke contact with males more frequently than with females. Other behavioral categories did not differ between the sexes. Our results suggest that higher nutritional demands of males compared with females may affect some behaviors. However, mothers of sons did not experience immediate trade-offs between current and future reproduction. Other behaviors, similarly expressed by the two sexes, suggest a similar developmental trajectory between male and female A. caraya infants, meaning that most differences emerge following the infant period.

How do demographic and social factors influence parent-offspring conflict? The case of wild black and gold howler monkeys (Alouatta caraya).

In this study, we examined the influence of demography and social context on mother-offspring conflict in wild black and gold howler monkeys (Alouatta caraya) inhabiting two nearby sites in northern Argentina, one comprising continuous forest and one fragmented forest. These sites differed in population density (3.25 vs. 1.04 individuals/ha), degree of home range overlap between neighboring groups (70 vs. 31%), and rate of intergroup encounters (2 vs. 0.02-1 encounters/day), though not in interbirth interval or rate of infant mortality. During a 27-month study (September 2008 through November 2010), we observed 37 mother-offspring dyads across the two sites. We found a very similar pattern of mother-offspring conflict in both populations; specifically, the sites did not differ in any of the variables used to characterize the mother-offspring relationship (the time spent in contact, the rate at which the mother makes and breaks contact, the rate at which the infant breaks contact, the rate of maternal rejection, and signs of infant distress) except one (the rate at which the infant makes contact). Although mother-offspring conflict is a dynamic process that varies over time, our results suggest that the different demographic and social contexts found at the two study sites did not have a marked effect on quantitative aspects of the mother-offspring relationship in these populations of black and gold howlers. Finally, this study suggests that the environmental variability (ecological, demographic, and social traits) leads to a set of strategies used both by infants and mothers with a main goal of conflict resolution, with mothers specifically aiming to cope with the tradeoff between current and future reproduction.

Preliminary study of mother-offspring conflict in black and gold howler monkeys (Alouatta caraya).

Parent-offspring conflict has been scarcely studied in Neotropical primates. In this study, we explored mother-offspring conflict in a group of wild black and gold howler monkeys (Alouatta caraya) in northeastern Argentina. We used the all-occurrences technique to record behaviors, completing 712 h of observation. The results showed that all immature individuals between 2 and 23 months expressed conflict with regard to suckling or traveling with their mothers. Successful suckling attempts negatively correlated with the age of the immatures, occurring least frequently with the presence of newborns. In the juvenile period, the decline in successful attempts was a consequence of juveniles reducing suckling attempts and mother rejection.

Births in wild black and gold howler monkeys (Alouatta caraya) in Northern Argentina.

Previous studies on births in nonhuman primates suggest that births are expected to occur at night to avoid predators. Here, we describe birth-related behaviors in wild black and gold howler monkeys, Alouatta caraya and address the various ideas proposed in the literature about the timing of births in group-living nonhuman primates. We collected data on females' birth-related behaviors through continuous focal observations and scan samples. Focal observations on females giving birth were taken for the remainder of the day after noticing a female was in labor. We recorded behaviors and the spatial distribution of the whole group using scan samples taken every 10 min from sunrise to sunset the same day of birth. We recorded five births at the continuous forest (CF) over a 25 months period (January 2004-December 2004 and September 2005-September 2006) and two births in the fragmented forest (FF) over a 13 months period (September 2005-September 2006). From these, four births were during daylight (two at CF and two at FF) and three during the night at CF. Our descriptions of A. caraya births contribute to a growing data set on the timing of parturition in wild nonhuman primates and suggest that a clear pattern of nocturnal births is not universal across nonhuman primate species.