Oscar Rocha-Barbosa

Mammals of Serra da Bocaina National Park, state of Rio de Janeiro, southeastern Brazil

Here we present a commented list of mammals registered in the Serra da Bocaina National Park. Three field trips (February, 2010, and May and July, 2011) were accomplished along the RJ-165 highway in the Municipality of Paraty, State of Rio de Janeiro, Brazil. Forty-eight species belonging to nine orders were recorded. The local mammal fauna could be considered diverse and rich, with some species regarded as biological indicators of habitat quality. Endangered and rare rodent species like Blarinomys breviceps , Juliomys rimofrons , and Thaptomys nigrita were captured. Road and hunting impacts on mammals are discussed.

Limb joints kinematics and their relation to increasing speed in the guinea pig Cavia porcellus (Mammalia: Rodentia)

The kinematics of each joint of the guinea pig Cavia porcellus were studied during the locomotor cycle at increasing speed by high-speed cinefluorography. The main objective was to reveal the functional specific features of these structural elements in each dynamic phase of the cycle and also which limb joints are important during the increase of animal speed. Most of the analysed angles in C. porcellus were affected as the speed increased, both in trot and gallop. However, only a few of them were correlated with speed. There were also differences with respect to symmetrical or asymmetrical gaits. Both pairs of limbs responded differently to the increase of speed; while the forelimb joints modified the duration of their action (frequency) more than the amplitude (stride length), the hindlimbs acted inversely. The movements of the joints during the stance phase changed dramatically with speed, particularly in the hindlimb. At knee level, the flexion amplitude increases to maintain the stiffness of the leg spring, a principle previously discussed as essential for the running process. In the swing phase, inertial effects are the main constraints and, as in the stance phase, the knee joint in the swing phase is correlated with speed both during trot and gallop, confirming the major importance of this joint to increasing speed.

Locomotion in Aquatic, Terrestrial, and Arboreal Habitat of Thick-Tailed Opossum, Lutreolina crassicaudata (Desmarest, 1804)

Abstract The reasons Lutreolina crassicaudata is always captured in close proximity to water are not clear. We investigated locomotory behavior and performance in swimming, running, climbing, and jumping of L. crassicaudata. One adult male was videotaped in the laboratory while swimming, walking on the ground and on a horizontal tube 1.2 m from the ground, climbing a tree trunk angled 45°, and jumping gaps between supports. The locomotor cycles in these different activities were described by speed, stride length, stroke or stride frequency, time of power and recovery phases or stance and swing phases, and by displacement of points on the animal. L. crassicaudata employed a quadruped paddling gait in swimming. Swimming speed was similar to that of terrestrial didelphids, but stroke frequency and buoyancy ability were more similar to those of the water opossum. Different gaits were used for locomotion in each habitat type and we conclude that L. crassicaudata cannot be considered a specialized species for aquatic locomotion.

Water Absorption of the Fur and Swimming Behavior of Semiaquatic and Terrestrial Oryzomine Rodents

Abstract Locomotion in land and water requires different adaptations, hence semiaquatic mammals must deal with conflicting demands of the 2 environments. Semiaquatic rodents of the tribe Oryzomyini are considered semiaquatic mostly based on habitat use and morphology, but locomotory specializations were not yet determined for most species of the group. We compared water absorption of the fur and swimming behavior between 2 species of oryzomyine water rats (Nectomys) and 2 terrestrial species of Cerradomys. We used adult rodents captured in the wild but acclimated to laboratory conditions. Water absorption rate was determined by the relative increase in body mass after a 5-min swimming session. Animals were videotaped swimming in an aquarium to determine gaits, body posture, maneuverability, and speed. Water absorption rate was significantly lower in semiaquatic species, with no significant difference between sexes. Bipedal paddling was the more frequently used gait by all 4 species, but semiaquatic species were faster and maintained a more hydrodynamic body posture, with a short gliding phase during the gait cycle. Only semiaquatic species were capable of floating effortlessly, and used the swimming bound, a gait similar to the half bound of terrestrial locomotion. Submerged swimming was the fastest swimming gait, used by 1 terrestrial and 1 semiaquatic species. The better performance during bipedal swimming of semiaquatic water rats was related to the improved buoyancy provided by reduced water absorption of the fur, which seemed to represent an important adaptation to move in the water without compromising locomotion on land.

ECOMORPHOLOGICAL RELATIONSHIPS IN SIX LIZARD SPECIES OF RESTINGA DA BARRA DE MARICÁ, RIO DE JANEIRO, BRAZIL

Estudiamos algunas relaciones ecomorfologicas en seis especies de lagartos (Ameiva ameiva, Cnemidophorus littoralis, Tropidurus torquatus, Liolaemus lutzae, Mabuya agilis y M. macrorhyncha) de la Restinga de la Barra de Marica, RJ. Estas especies poseen marcadas diferencias en la utilizacion del microhabitat y en el comportamiento en la busqueda de alimento, que varia de activo a «sienta-y-espera». Comparamos la morfologia de los dedos y de las garras de especies de lagartos con estos comportamientos diferentes. Las especies que mostraron el grado mas alto de arborealidad (T. torquatus e M. macrorhyncha) tenian el 4o dedo del miembro anterior como el mas grande, y las otras especies tenian el 3o. Esto parece otorgarle una ventaja para la sustentacion vertical de las especies arboreas. Todas las especies tenian el 4o dedo como el mas grande del miembro posterior. Los dos scincideos (M. agilis e M. macrorhyncha) tenian garras mas cortas y curvas, que parecen ajudarle para la escalada de las hojas de la bromelia Neoregelia cruenta. Adicionalmente, las garras de las especies esencialmente terricolas son mayores que las de otras especies, sugeriendo que garras mayores confieren un mejor apoyo en la arena (dandole mejor impulso y velocidad), en la excavacion de escondrijos, en la defensa contra los predadores, en la disputa por sitios de alimentacion y en la seleccion sexual. En el estudio, la estrategia de alimentarse no parece estar relacionada con el tamano absoluto de los dedos de los lagartos, pero si con las diferenciass relativas en los dedos de los miembros anteriores

A biomechanical approach on the optimal stance of Anhanguera piscator (Pterodactyloidea) and its implications for pterosaur gait on land

The stance of pterosaurs on land is traditionally a controversial question. Here, we show that pterosaurs like Anhanguera piscator were quadrupeds. An osteological model of A. piscator was three-dimensionally built in digital space. The reconstructed muscles of its pelvic girdle were then placed on their points of origin and insertion to allow the biomechanical calculations to find the most efficient stance on land to be performed. The hindlimb readjustment (i.e. the repositioning of the hindlimb according to the achieved results) led to a pelvic counterclockwise displacement at 10°, which means that the ilium previously placed at 0° regarding an axis parallel to the ground was moved (and so the whole pelvis) 10° up from the preacetabular process. This new position prevents A. piscator from having a fully upright stance. A 10° displacement of the pelvic girdle would compel the forelimbs to be highly sprawled. Therefore, this study affords A. piscator having a quadrupedal gait and demonstrates that a bipedal stance is not viable once the lever arm values decrease abruptly both for extensor and flexor muscles during the femoral extension. This is the first time this approach is used to shed light on this question.

Excavatory cycle of Leposternon microcephalum Wagler, 1824 (Reptilia, Amphisbaenia)

Los movimientos excavatorios de la Amphisbaenia (culebrilla ciega), con hocico en forma de pala, Leposternon microcephalum (Reptilia: Squamata) se estudiaron con la ayuda de tecnicas de videofluoroscopia (rayos X). Esto permite la observacion de los movimientos del craneo y columna, a lo largo de tuneles, y una propuesta mas detallada, siendo un enfoque novedoso para investigaciones de la culebrilla ciega excavadora. Un solo especimen de Leposternon microcephalum se mantuvo en un terrario de vidrio lleno de semolina, y fue filmado con una maquina de escopia (rayos X). Se fijaron marcas anatomicas en la cabeza de este y luego fueron dibujadas desde las grabaciones. Las secuencias seleccionadas de las grabaciones fueron fragmentadas en fotogramas aislados de la observacion del movimiento. Los analisis de las grabaciones revelaron un patron repetitivo de ciclos excavatorios, con la retirada y doblamiento hacia abajo de la cabeza, antes de su movimiento hacia arriba para compactar el sustrato del techo del tunel. Sigue una caida de la cabeza, que se pone sobre el apoyo del sustrato para la proxima retirada y doblamiento hacia abajo de la cabeza. Esto es un paso esencial que es descuidado en las descripciones anteriores del ciclo. La primera flexion baja de la cabeza no fue debidamente descrita anteriormente para Amphisbaenia con hocico en forma de pala. Los movimientos excavatorios de estos animales suelen ser tratados como un periodo de dos ciclos intensificados, pero la evidencia que este ciclo excavatorio consta de tres pasos, se dan aqui.

Syntopy of cryptic Phyllomys (Rodentia: Echimyidae) species: description of the karyotype of Phyllomys nigrispinus and an expansion of the geographic distribution of Phyllomys sulinus

Abstract The echimyid rodents of the genus Phyllomys are medium-sized arboreal spiny rats endemic to the Atlantic Forest of Brazil. The genus is currently composed of 13 species, although there are at least four other undescribed species. The ecology, zoogeography and diversity of the genus are still poorly understood. Here, we provide the first record of Phyllomys sulinus from the Brazilian state of Rio de Janeiro, based on a specimen collected in the Serra da Bocaina National Park, which extends the known geographic range of the species approximately 130 km to the northeast. At this site, P. sulinus occurred in syntopy with the cryptic Phyllomys nigrispinus. We describe the karyotype of P. nigrispinus for the first time and identify two different diploid numbers (2n=84 and 85). We also conducted a molecular analysis of the cytochrome b gene of five specimens, which we identified by phylogenetic reconstruction. Our findings reinforce the importance of molecular data, such as DNA sequences, and karyotypes for the differentiation of cryptic, syntopic species.

Origin and Antimeric Distribution of the Femoral Nerves in New Zealand Rabbits

Se estudio el origen y distribucion del nervio femoral de ambos antimeros en 30 conejos neozelandeses, 15 machos y 15 hembras. Los animales fueron recolectados despues de su muerte natural y se fijaron en formaldehido al 10%. En los machos, el nervio femoral se origino a partir de los ramos ventrales del cuarto, sexto y septimo nervios espinales lumbares en siete casos (46,67%); en tres casos (20%) desde los ramos ventrales del quinto, sexto y septimo nervios espinales lumbares; en dos casos (13,33%) desde los ramos ventrales del quinto y sexto nervios espinales lumbares, mientras que en tres animales (n=1 respectivamente), desde los ramos ventrales del quinto nervio espinal lumbar (6,67%), los ramos ventrales del cuarto y quinto nervios lumbares espinales (6,67%) y desde los ramos ventrales del quinto y septimo nervios espinales lumbares. En las hembras, el nervio femoral se origino a partir de los ramos ventrales del cuarto, sexto y septimo nervios espinales en cuatro casos (26,67%); en otros cuatro casos (26,67%) desde los ramos ventrales del quinto, sexto y septimo nervios espinales lumbar, en tres casos (20%) desde los ramos ventrales del sexto y septimo nervios espinales lumbares, en dos casos (13,33%) desde los ramos ventrales del quinto y sexto nervios espinales, y en dos animales (n=1, respectivamente) procedian desde los ramos ventrales del quinto nervio espinal lumbar (6,67%) y de los ramos ventrales del cuarto y septimo nervios espinales lumbares (6,67%). Los nervios femorales en todos los animales estaban distribuidos en diversos ramos de los musculos psoas mayor y menor, cuadriceps femoral sartorios y pectinatos.

Juliomys rimofrons Oliveira and Bonvicino, 2002 (Rodentia: Cricetidae): Distribution extension

Until now, Juliomys rimofrons Oliveira and Bonvicino, 2002 has been known only from the type locality, the county of Itamonte, State of Minas Gerais, Brazil. Based on morphological and karyological examinations, in this study we identified two new records for this species. Both records correspond to individuals collected at Serra da Bocaina National Park, in the states of Rio de Janeiro and Sao Paulo, Brazil. These records increase the species’ geographic range southwards, approximately 100 km from the type locality.