Mazama gouazoubira (G. Fischer)

VOSS, ROBERT S., LUNDE, DARRIN P. & SIMMONS, NANCY B., 2001, The Mammals Of Paracou, French Guiana: A Neotropical Lowland Rainforest Fauna Part 2. Nonvolant Species, Bulletin of the American Museum of Natural History 2001 (263), pp. 1-236 : 72-77

Mazama gouazoubira (G. Fischer)

VOUCHER MATERIAL: AMNH 265960 , 265961 ; MNHN 1995.960 . Total = 3 specimens .

IDENTIFICATION: Both of our adult examples, one male (MNHN 1995.960) and one female (AMNH 265961), agree closely with Husson’s (1978) qualitative description of Surinamese specimens that he identified as Mazama gouazoubira nemorivaga . Measurements of our vouchers (table 16) likewise correspond closely with morphometric data from M. g. nemorivaga summarized by Husson (1978: table 61) and Bisbal (1991: table II). In qualitative cranial traits, our two adult skulls conform with Medellín et al.‘s (1998) characterization of northern South American populations of M. gouazoubira , except that the mesopterygoid fossae of both specimens have broadly U­shaped (not V­shaped) anterior margins.

Our vouchers are practically topotypes of Cervus nemorivagus F. Cuvier , the description of which was based primarily on specimens from Cayenne (Allen, 1915b; contra Miranda­Ribeiro, 1919). Although this taxon is currently considered a subspecies of Mazama gouazoubira (e.g., by Czernay [1987] and Grubb [1993], presumably following Ávila­Pires [1959]), no revisionary study based on extensive specimen data has, in fact, shown that the small grayish brockets

TABLE 16 Measurements (mm) and Weights (kg) of Adult Mazama gouazoubira from Paracou

of the Guianas and those of Paraguay (the type locality of gouazoubira ) are really conspecific. The character differences that Tate (1939) observed between specimens that he referred to M. nemorivaga and M. simplicicornis Illiger (= M. gouazoubira ) should be carefully evaluated in any future taxonomic analysis of these deer.

REMARKS: The specific epithet of the gray brocket was originally spelled ‘‘ gouazoupira ’’ as noted by Grubb ( 1993). However, gouazoubira is the spelling that has been followed almost universally for many years, and we agree with Gardner (1999) that this usage should be maintained in the interest of nomenclatural stability.

FIELD OBSERVATIONS: Our three vouchers were all shot at night in well­drained primary forest. The still­nursing fawn (its stomach containing milk only) and the lactating adult female were collected together, whereas the young adult male (with antlers in velvet) was apparently solitary. In addition, L. H. Emmons observed what was probably a single individual on four different nights from 21 September to 10 October 1993 in welldrained primary forest.

According to P. Petronelli (personal commun., 1993), gray brockets are less common at Paracou than are red brockets, but they are nevertheless often sighted by forestry per­ sonnel, about 10–12 times per year on average.

Pecari tajacu (Linnaeus)

Collared peccaries were once common at Paracou, but although we often saw tracks and wallows (usually in parts of the forest distant from our normal inventory activities), we rarely saw the animals themselves. According to P. Petronelli (personal commun., 1993), this species is typically encountered locally in groups of 6–7 animals, always in the daytime, about 6–8 times per year on average.

Tayassu pecari (Link)

Groups of about 20 white­lipped peccaries have been sighted at Paracou on at least three occasions, all in the daytime (P. Petronelli, personal commun., 1993). Bushnegro forestry workers say that such groups visit the area about every four years. Although we did not see the animals themselves in the course of our 1991–1994 inventory fieldwork, L. H. Emmons observed fresh tracks of this species in primary forest on 12 October 1994.

RODENTIA

Rodents constitute the most diverse group of nonvolant mammals at Paracou, where we documented the occurrence of 22 species in six families: Sciuridae (2 species), Muridae (11 species), Erethizontidae (2 species), Dasyproctidae (2 species), Cuniculidae (1 species), and Echimyidae (4 species). An additional 11 species are known from other localities in French Guiana or Surinam (appendix 1), and some of these could also be expected to occur in our study area. Two species are described as new below.

Predictably, most Paracou rodent identifications proved to involve significant taxonomic problems, the resolution of which occupies the bulk of the following accounts. We define specimens to be adult if the permanent dentition is fully erupted, subadult if the molar dentition is completely erupted but the permanent premolars are not, and juvenile if one or more molars are incompletely erupted. Our quantitative comparisons of rodent crania and dentitions are based on the following measurements (figs. 33, 34).

Condylo­incisive Length (CIL): From the greater curvature of one upper incisor to the articular surface of the occipital condyle on the same side.

Length of Diastema (LD): From the crown of the first cheektooth to the lesser curvature of the incisor on the same side (except as noted in some tables, where the alveolar equivalent was measured).

Maxillary Toothrow (MTR): Crown length, from P4 to M3 (except as noted in some tables, where the alveolar equivalent was measured).

Length of Molars (LM): Crown length from M1 to M3.

Breadth of M1 (BM1): Greatest crown breadth of the first maxillary molar.

Length of Incisive Foramen (LIF): Greatest anterior­posterior dimension of one incisive foramen.

Breadth of Incisive Foramina (BIF): Greatest transverse dimension across both incisive foramina.

Breadth of Palatal Bridge (BPB): Measured between the protocones of the right and left first maxillary molars (= ‘‘Anterior Palatal Breadth’’ of Voss and Angermann, 1997).

Breadth of Zygomatic Plate (BZP): Least distance between anterior and posterior edges of the zygomatic plate.

Length of Rostrum (LR): From the tip of one nasal bone to the posterior margin of the zygomatic notch on the same side.

Length of Nasals (LN): Greatest anterior­posterior dimension of one nasal bone.

Least Interorbital Breadth (LIB): Least distance across the frontal bones between the orbital fossae.

Breadth of Braincase (BB): Greatest transverse dimension across the braincase above and slightly behind the squamosal zygomatic processes.

Zygomatic Breadth (ZB): Greatest transverse dimension across the squamosal zygomatic processes (= ‘‘Posterior Zygomatic Breadth’’ of Voss and Angermann, 1997).

Zygomatic Length (ZL): From the posterior mar­ gin of the infraorbital foramen to the posterolateral corner of the zygomatic arch.

A few other measurements taken for special purposes are defined as necessary in the text and tables that follow. Because sexual dimorphism is an insignificant source of measurement variation in most rodents (e.g., see Straney [1978] and references cited by Voss [1988: 362]), we do not summarize morphometric data separately by gender.

Most of the larger rodents in the Paracou fauna (all sciurids, erethizontids, dasyproctids, and Cuniculus paca ) can be identified at a distance by obvious external characters (Emmons, 1990, 1997), but most of the smaller rodents cannot be confidently identified without specimens in hand, and some closely related species cannot be unambiguously distinguished except from cleaned cranial material. In lieu of keys, we provide tabular summaries of diagnostic traits to facilitate identifications in some speciose genera.

SCIURIDAE

The two squirrels that we found at Paracou are the only species known to occur in French Guiana, Surinam, and Amapa´; therefore, no future additions to the local sciurid fauna are expected. Pending a revision of the complex nomenclature of these animals (M. de Vivo, in prep.), we follow the usages recommended by Husson (1978), who examined type material that we have not seen.

Sciurillus pusillus (E. Geoffroy)

VOUCHER MATERIAL: AMNH 269119. Total = 1 specimen.

IDENTIFICATION: Our voucher is almost topotypical of this species (originally described from specimens collected at Cayenne) and exhibits the reddish head, black ear tips, and white postauricular patches said to distinguish S. p. pusillus from other nominal taxa of South American pygmy squirrels (Anthony and Tate, 1935; Husson, 1978). The external dimensions of AMNH 269119, an adult female, were 109 Χ 74 Χ 28 Χ 14 mm; including two embryos in utero, this specimen weighed 51 g. Because fluid­preserved material of Sciurillus is rare in museum collections, we did not extract the skull of AMNH 269119 for measurement.

REMARKS: For the availability of names from Geoffroy’s (1803) catalog (rejected by Wilson and Reeder, 1993: 831), see Hershkovitz (1955) and Holthuis (1963).

FIELD OBSERVATIONS: Our single voucher was shot by L. H. Emmons at 11:45 hours on 21 September 1994 as it fed on something growing on (or concealed beneath) the bark of a large Inga sp. (Mimosoideae) at a height of about 18 m in well­drained primary forest. In addition, we recorded fleeting diurnal observations of this species on five dates from 1991 to 1993; all of these sightings were of solitary individuals in trees in well­drained primary forest.

Sciurus aestuans Linnaeus

VOUCHER MATERIAL: AMNH 266485– 266488 , 266492 , 266493 , 267013 , 267565 ; MNHN 1995.989 – 1995.991 . Total = 11 specimens .

IDENTIFICATION: Our voucher material agrees closely in most details with Husson’s (1978: 386–387) description of topotypic specimens from Surinam, but several points of comparison merit comment. (1) According to Husson, a few Surinamese examples have ‘‘very inconspicuous buffy yellow postauric­

TABLE 17 Measurements (mm) and Weights of Adult Sciurus aestuans from Paracou

ular patches’’, but most do not; there is no trace of a postauricular patch on any specimen from Paracou. (2) Husson described the ventral coloration as ‘‘usually pale reddish brown, sharply separated from the colour of the dorsal surface, at least in about the middle of the body, but considerably less so in the anterior and posterior parts’’. By contrast, Paracou skins have clear (self­colored) orange fur on the chest, fading to buff or cream on the throat; some clear orange fur extends posteriorly along the ventral midline onto the abdomen, but most of the abdominal fur is gray­based, appearing grizzled like the flanks although much paler. (3) Some Surinamese specimens have substantially smaller measurements (op. cit.: table 62) than our vouchers (table 17), but it is possible that Husson included subadults in his sample.

This species (together with other members of the so­called aestuans group of Sciurus ) was referred to the genus Guerlinguetus Gray by Allen (1915a), Tate (1939), Moojen (1942), Moore (1959), and others, but most recent authors have followed Cabrera (1961) in treating Guerlinguetus as a subgenus of Sciurus . Cabrera cited no published analysis of character data to support his opinion, however, and it seems probable that renewed morphological and molecular studies of Neotropical squirrels will advocate a return to the older generic usage.

Although the currently accepted synonymy (Hoffmann et al., 1993) for Sciurus aestuans implies that this species is distributed throughout eastern Amazonia to southeastern Brazil (including such forms as alphonsei Thomas, garbei Pinto, henseli Miranda­Ribeiro, ingrami Thomas, poaiae Moojen, and roberti Thomas ; see Cabrera [1961] for bibliographic citations and type localities), we follow the last substantive specimen­based revisionary treatment of Amazonian squirrels (Moojen, 1942) in restricting S. aestuans to the Guiana subregion of Amazonia. In the Amazonian lowlands of southeastern Venezuela (geographically part of the Guiana subregion), however, S. aestuans is replaced by a different species that is usually identified (e.g., by Tate, 1939; Handley, 1976; Linares, 1998) as S. gilvigularis Wagner.

FIELD OBSERVATIONS: Sciurus aestuans is one of only three common diurnal rodents at Paracou. Most (9) of our 11 voucher specimens were shot in the daytime, and we recorded an additional 11 unvouchered daytime sightings in our fieldnotes; two trapped specimens were found at or near dawn, but might have been captured the preceding afternoon. With the exception of the latter, which were taken near ground level in Conibear and leghold traps set on tree trunks over a small stream, all of our observations of this species at Paracou were of animals perched in trees at heights of 3–30 m above the ground. Most individuals were solitary, but an adult male and an adult female were collected together on 13 August 1991. Habitat data accompanying specimens or sight records include 16 observations in primary forest at both well­drained and swampy sites, and 5 in more­or­less disturbed habitats.

MURIDAE

All of the genera of rainforest murids known to occur in the Guiana subregion of Amazonia are documented by vouchers collected at Paracou, including species of Neacomys , Nectomys , Neusticomys , Oecomys , Oligoryzomys , Oryzomys , and Rhipidomys . Although most Guianan murids can be provisionally identified to genus in the field by external characters described by Husson (1978) and Emmons ( 1990, 1997), we pro­ vide illustrations and supplementary information to facilitate field determinations of problematic taxa. Our anatomical terminology for muroid morphological characters follows that referenced or defined by Reig ( 1977), Voss (1988, 1993), Carleton and Musser (1989), Voss and Carleton ( 1993), and Musser et al. (1998).