Phylloderma stenops Peters, 1865

Ph [yllostoma] (Phylloderma) stenops Peters, 1865: 513.

G [uandira] cayanensis Gray, 1866: 114

Phylloderma stenops – Dobson, (1878: 483): recognition of Phylloderma as a genus and invalidation of Guandira cayanensis

Phylloderma septentrionalis (partim) – Goodwin (1940: 1)

Phylloderma stenops – Handley (1966: 762): recognition of Phylloderma stenops septentrionalis

Phyllostomus stenops – Baker et al. (1988: 13)

Phylloderma stenops – Timm et al. (1989: 46): return to the use of Phylloderma

Content.

Two subspecies are recognized: Phylloderma stenops stenops and P. s. boliviensis.

Examined material.

52 specimens including 52 skins, 52 skulls, 13 complete mitochondrial genomes.

Holotype.

Adult, probably male, skin with skull removed (RNH 16843), collector and date of capture unknown. The specimen might be in the Rijksmuseum van Natuurlijke Historie, Leiden, Netherlands (Carter and Dolan 1978).

Type locality.

Cayenne, French Guiana (Peters 1865). Geographic coordinates for the type locality are not available in the original description or other known sources.

Diagnosis.

Phylloderma stenops is characterized by its moderate size within the genus (FA 63.7–81 mm; GLS 29–35.4 mm), rounded ears with marked inner striations, and a flatter facial profile. It differs from P. septentrionalis by the presence of smooth or weakly bilobed upper inner incisors, a pointed main cusp on the third lower premolar (p 4), and taller upper molar cusps with more developed metastylar and parastylar shelves. The skull is less massive, with a slightly longer and flatter rostrum. Externally, the underparts are uniformly colored.

Amended description.

Phylloderma stenops can be characterized as a large and robust bat. Reported measurements for this species, including the ranges from this study, are total length 80–128 mm; forearm length 63.7–81 mm; and greatest skull length 29–35.42 mm (Ramírez-Fráncel et al. 2015; Bomfim et al. 2017; Solari et al. 2019). Apart from the general characteristics of its genus, this species is distinguished by a robust skull, and a low (relatively flat) facial profile. The chin is bare, V-shaped, and encircled by a cushion bordered by a row of rounded or elongated papillae (Trujillo and Albuja 2005). The nose leaf is wide at the base and has a pointed tip. The fur is short, with dorsal hair exhibiting a reddish-brown color. The wing membranes attach high on the back, creating a partially nude appearance; the wingtips are whitish. The ears are well separated, moderately large, and rounded; the tragus is long and slender. The calcar is approximately equal to or shorter than the length of the foot, and the tail extends only halfway inside the uropatagium, protruding slightly from the dorsal surface (Husson 1962; Bárquez and Ojeda 1979; Emmons and Feer 1999; Díaz et al. 2011; Martínez-Cerón et al. 2019).

The upper inner incisors are relatively long compared to the external ones, with smooth or weakly bifid cutting edges, and usually converging distally. The upper external incisors are bilobed and slightly less than half the size of the internal ones. Bárquez and Ojeda (1979), referring to Phylloderma stenops boliviensis, pointed out that its upper internal incisors are not bilobed; although it may be a characteristic of the subspecies, or of the two individuals used for the description; this cannot be considered a diagnostic character because there is variability in the sample studied. The lower inner incisors are bilobed, or at least a medial notch is visible which denotes that they are weakly bilobed (Fig. 4). The lower external incisors have cutting edges that are irregular, but are not evidently bilobed, are smaller than the internal ones, and are covered by the cingula of the canines. Bárquez and Ojeda (1979) also pointed out that the four lower incisors are even, probably referring to the fact that they are not bilobed; but again, although it may be a characteristic of the subspecies, or of the two individuals used for the description of P. s. boliviensis, this is not a diagnostic character of the species. The upper canines are subtriangular, the anterior face of the upper canine lacks longitudinal grooves. There is a prominent cingulum on the anterolingual side, in contact with or covering the back of the upper external incisors. The lower canines rise prominently above the level of the incisors when viewed from the front. The anterior upper premolar (P 1) is in contact with the canine and with the posterior upper premolar (P 3), and the posterior cingulum is mounted on the labial side. P 3 is caniform, with its posterior cusp in contact with M 1. The anterior lower premolar (p 2) rests on the canine. The second premolar (p 3) is minuscule and enclosed between the other premolars and is not displaced lingually from the toothrow. The main cusp of the third premolar (p 4) is pointed. The upper molars are large, with a tall anterior paracone and a posterior metacone, and with radiating crests with a distinct W-shaped pattern. The metastylar and parastylar shelves are relatively large and give the impression of tall crowns. M 3 has a postparacrista only and is V-shaped. The trigonids of the lower molars have a large buccal protoconid flanked anterolingually by the paraconid, and posterolingually by the metaconid. When viewed laterally, the dental arcade of the lower molars is sharp and serrated.

The braincase is relatively high and rounded. The rostrum is shorter than the braincase and has a dorsal profile that is not convex and does not have a depression between the orbits. The zygomatic arches are rounded and complete.

The diploid number is 32, and the fundamental number is 58 (de Souza et al. 2022).

Comparisons.

All craniodental and external measurements average smaller in P. stenops than in P. septentrionalis, with overlapping ranges except for GLS, MET III, MET IV, and MET V. The skull differs in size but not in shape. The upper inner incisors have smooth or weakly bifid cutting edges in P. stenops, as opposed to being clearly bifid in P. septentrionalis. The main cusp of the third lower premolar (p 4) is more pointed in P. stenops than in P. septentrionalis. The metacones and paracones are not as deep, and the metastylar and parastylar shelves are relatively shorter in P. septentrionalis than in P. stenops. The ears of P. stenops are rounded with distinct marginal striations on the inner surface, whereas in P. septentrionalis the ears are more pointed with less visible striations (Bárquez and Ojeda 1979) (Fig. 4).

A comparison of the two South American subspecies reveals that P. s. boliviensis is larger than P. s. stenops, although this conclusion is based on the only two specimens reported to date. The lower incisors of P. s. stenops are even and unlobed, whereas in P. s. boliviensis the middle incisors are longer than the outer ones and weakly bilobed (as in P. septentrionalis). The dorsal fur of P. s. stenops is distributed uniformly, whereas in P. s. boliviensis there is a clearer zone at the level of the neck (Bárquez and Ojeda 1979).

Distribution and habitat.

The species is distributed from the south of the Central Cordillera in Panama to South America, including the Guianas, Venezuela, Trinidad and Tobago, Colombia, Ecuador, Peru, Bolivia, and Brazil (Fig. 5). The species is considered rare, and primarily inhabits lowland and humid vegetation types, such as evergreen, mesic or riparian forests, inundated floodplain forests, deciduous forests, also extending into drier regions such as dry and xeric shrublands (Williams and Genoways 2008; Carrera et al. 2010; Salas et al. 2014; Ramírez-Fráncel et al. 2015; Bomfim et al. 2017). Salas et al. (2014) recorded the species in a place heavily disrupted by livestock, with small remnants of riparian vegetation.

Natural history.

There is limited knowledge regarding the natural history of the genus Phylloderma. Apparently, P. stenops is omnivorous. Its diet consists primarily of fruits of the families Annonaceae, Cucurbitaceae, Myrtaceae, and Cecropiaceae; and has been documented consuming adult insects, insect larvae, and pupae from an active nest of a social wasp (Jeanne 1970; Giannini and Kalko 2004), as well as lizards in captivity (Pye 1967). The species typically inhabits tropical forests below 1000 m (Carrera et al. 2010) and seems to prefer to forage in natural clearings beneath the dense canopy of pristine lowland forests (Koopman 1976). Phylloderma stenops commonly roosts in caves (Esbérard and Faria 2006). Based on observations in captivity in Brazil, Esbérard (2012) affirmed that P. stenops shows a polyestrous strategy, with seasonal reproduction and presents birth synchrony and postpartum oestrus; also, the gestational period does not exceed 167 days, and sexual maturity is reached around the age of 241–285 days. The bat fly, Strebla christinae, has been reported from this species (Handley 1966).

Remarks.

Peters (1865) originally described the species based on a mounted specimen, without taking measurements, providing only a description of dental numbers and shape, as well as of the form of the skull, noting its similarity to that of Phyllostomus. He mentioned size and shape to be comparable to those of P. hastatus, a species from which it is differentiated by a narrower shoulder girdle (Peters 1865). Handley (1966) observed specimens from Panama to exhibit mixed traits of both nominal species of Phylloderma (P. stenops and P. septentrionalis), yet agreeing more with the former. Consequently, he referred to the Panamanian individuals as P. s. stenops, thus acknowledging subspecific differentiation, and synonymized septentrionalis with stenops.