Water dispersal of Amphisbaena alba and Amphisbaena amazonica (Squamata: Amphisbaenia: Amphisbaenidae) in Brazilian Amazonia

. Information on the use of aquatic environments by two species of amphisbaenids ( Amphisbaena amazonica Vanzolini, 1951 and Amphisbaena alba Linnaeus, 1758) are presented. These findings suggest that aquatic environments are not a barrier to these animals, until now considered as strictly fossorial. New studies on amphisbaenians in natural conditions are needed in order to better understand which species may use water environment during dispersal events and the frequency of this behavior in the group.

specimens in museum collections, there is still a lack of information about the biology of the group in the wild. SEÑARIS (1999) observed that when disturbed by a collector in the floodplain of the Orinoco River, state of Anzoátegui, Venezuela, Amphisbaena gracilis Strauch, 1881 tried to escape immediately towards the water. According to SEÑARIS (1999), the swimming behavior of A. gracilis probably is an escape response to its natural predators.
Herein, we provide data on the utilization of the aquatic environment by two amphisbaenid species (Amphisbaena amazonica Vanzolini, 1951 andAmphisbaena alba Linnaeus, 1758) in natural conditions in the National Forest of Caxiuanã, Portel, and Melgaço municipalities, state of Pará, Brazil ( Our first record of the utilization of the aquatic environment by A. alba is from August 19, 2005 at 10:00 a.m. A single specimen of Amphisbaena alba (weight = 185g; snout-vent length [SVL] = 525 mm; tail length [TL] = 47 mm; Fig. 2) was collected, around 2.5 kilometers away from the left and the right margins in Baía de Caxiuanã (01º56'29.2"S, 51º27'26.5"W), municipality of Portel, Pará. The air temperature was 35.3°C, with slow wind and calm waters. The specimen swam through serpentine movements. During the aquatic locomotion, the specimen kept its face level with the surface of the water column and approximately every 10 seconds it lifted its head above the water to breath. We collected this specimen using a motorboat.
Our second recording occurred on May 15, 2006 at approximately 2:00 p.m. We collected a single specimen of A. amazonica (weight = 12 g; SVL = 228 mm; TL = 32 mm; Fig. 3) approximately 15 meters away from the left and right margins of the Igarapé Marinaú (01º49'33.88"S, 51º20'24.20"W), approximately 2,000 m before it meets the Baía de Caxiuanã, municipality of Portel, Pará. We observed the specimen to be swimming at a faster pace (marked by a stronger stroke) than our previous record of the A. alba, although it displayed the same serpentine movements. The frequency with which the specimen raised its head above the water was also higher than A. alba. This behavior was observed for approximately 10 minutes without any response to our presence. We collected this specimen using a kayak.
Our third record is of another specimen of A. amazonica that we observed on July, 24, 2007 at approximately 4:30 p.m., in the Igarapé Curuá (01º44'12.79"S, 51º27'11.04"W), at Scientific Station of Ferreira Penna, municipality of Melgaço, Pará. We were unable to collect this specimen and therefore lack its meristic data. We observed the specimen moving through the water column around aquatic macrophytes (Nymphaea sp.) at the same speed as our other specimen of A. amazonica (Fig. 4), and it raised its head to approximately the same height as our previously recorded A. amazonica.
Although the reasons for which these strictly fossorial species were in the water are unknown, we suggest that perhaps in extreme situations-such as when escaping from predators-amphisbaenids may move towards water. HEMBREE (2006) and ALBERT et al. (2007) have suggested that amphisbaenian species display low dispersal capabilities. Nevertheless, herein we report dispersals of A. alba and A. amazonica across water, one of the A. alba having crossed 2.5 km of open water, suggesting that these amphisbaenian species can overcome what we thought could be natural aquatic barriers. Our findings emphasize the need to conduct further ecological studies of amphisbaenians in their natural habitats in order to gain a better understanding of the dispersal capabilities of these fossorial squamates.