Rhynchonycteris naso Wied-Neuwied, 1820

Velazco, Paúl M., Voss, Robert S., Fleck, David W. & Simmons, Nancy B., 2021, Mammalian Diversity And Matses Ethnomammalogy In Amazonian Peru Part 4: Bats, Bulletin of the American Museum of Natural History 2021 (451), pp. 1-201 : 20-22

Rhynchonycteris naso Wied-Neuwied, 1820

Figure 6

VOUCHER MATERIAL (TOTAL = 24): Amelia (FMNH 19960–19967), Isla Padre (MUSM 4355), Jenaro Herrera (AMNH 278459), Nuevo San Juan (AMNH 272684, 272685, 272835, 272852, 273141, 273150, 273175; MUSM 13248– 13251, 15264–15266); see table 7 for measurements.

UNVOUCHERED OBSERVATIONS: Roosting groups of Rhynchonycteris naso were observed at Anguila and Wiswincho during the Tapiche- Blanco Rapid Biological Inventory (Escobedo- Torres, 2015). Additionally, four individuals of R. naso were captured at Quebrada Buenavista during the Yavarí Rapid Biological Inventory (Escobedo, 2003), and we captured another three individuals at El Chino Village in 2019. Rhynchonycteris naso was also identified using acoustic methods during the CEBIO bat course at Jenaro Herrera.

IDENTIFICATION: Rhynchonycteris is a widespread monotypic genus that ranges from Mexico to eastern Brazil (Simmons, 2005; Simmons and Cirranello, 2020). Rhynchonycteris is easily distinguished from other Neotropical emballonurids by the absence of wing sacs, and by having a long nose that projects well beyond the lower lip, two pale dorsal stripes, frosted dark-brown dorsal fur, a dark-brown face contrasting with much paler ventral fur, and forearms that are sparsely haired but adorned with tufts of whitish fur (Reid, 2009; López-Baucells et al., 2018). The following craniodental characters are also useful for diagnosing this species: a first upper premolar that is tricuspidate, relatively large, and slightly triangular in occlusal view; absence of a sagittal crest; and a flat dorsal profile due to the absence of any angulation between the rostrum and braincase (Sanborn, 1937; Goodwin and Greenhall, 1961; Plumpton and Jones, 1992; Jones and Hood, 1993; Hood and Gardner, 2008). Measurements of Rhynchonycteris were provided by Husson (1962, 1978), Brosset and Charles-Dominique (1990), and Simmons and Voss (1998). No subspecies are currently recognized (Hood and Gardner, 2008).

Osgood (1914) and Fleck et al. (2002) correctly identified their specimens from Amelia (“Nazareth”) and Nuevo San Juan, respectively, as Rhynchonycteris naso . Specimens from the Yavarí-Ucayali interfluve are morphologically indistinguishable from the French Guianan material reported by Simmons and Voss (1998) and from specimens from Bolivia (e.g., AMNH 248745), Brazil (e.g., AMNH 93941), Colombia (e.g., AMNH 78707), Ecuador (e.g., AMNH 67611), Trinidad and Tobago (e.g., AMNH 176618), and Venezuela (e.g., AMNH 78352).

REMARKS: Ascorra et al. (1993) reported finding a group of about 20 individuals of Rhynchonycteris naso roosting under a bridge over a stream at Jenaro Herrera, and one individual was taken in a ground-level mistnet near a stream at this locality in 2012. At El Chino Village, three individuals were mistnetted above the town plaza in February 2019.

At Nuevo San Juan we captured four specimens in ground-level mistnets on river beaches or sandbars, but the remaining specimens from this locality were taken at roosts. All the roosts of Rhynchonycteris naso that we found near Nuevo San Juan were in exposed locations on the trunks or branches of dead trees partially submerged in the Río Gálvez : (1) a group of six individuals (of which one adult male was collected) were perching about 1.5 m above the water on 12 October 1999; (2) a group of three individuals (of which one adult male and one adult female were collected) were perching about 1 m above the water, also on 12 October 1999; and (3) a group of six or seven individuals (of which one adult female was collected) were perching at an unrecorded height above the water on 21 October 1999. In all three cases, the observed roosting groups of R. naso were unaccompanied by other bat species.

The roosts in which we found Rhynchonycteris naso near Nuevo San Juan closely resemble those previously reported in the literature for this very widespread species, which is almost always found over water (Husson, 1962; Tuttle, 1970; Bradbury and Emmons, 1974; Bradbury and Vehrencamp, 1976; Brosset and Charles-Dominique, 1990).

Figures

FIG. 6. Photographs of A, an adult female (ROM 122161) Rhynchonycteris naso captured at Jenaro Herrera; and B, a group of three adults R. naso roosting under a palm-thatched roof at El Chino Village. Photographs by Burton Lim (A) and Brock Fenton (B).