A chromogenetic field analysis was performed with 25 of 29 of the known species of the genus Callicebus. Some species presented polymorphism, such as C. moloch, C. hoffmansii and C. cupreus. C. bernhardi presents the same distribution of color in chromogenetic fields as C. moloch, differing only in pigment amount, mainly in ventral surfaces, suggesting C. bernhardi is a junior synonym of C. moloch. C. hoffmansii presents two distinct phenotypes, but without a geographic barrier between them. Callicebus cupreus, C. dubius and C. caligatus are distinct species.
Although new species of Callicebus have been described from Brazil and Bolivia during the last decade, few taxonomic studies had been made on this genus during the same period. The first taxonomic review was performed by Elliot (1913), who recognized 22 monotypic species. This arrangement has been modified by several researchers, such as Tate (1939), Thomas (1927), Lönnberg (1939), Cruz-Lima (1945), Vieira (1955) and Cabrera (1958), who proposed more detailed taxonomic arrangements, defined geographical distributions and suggested phylogenetic relationships within the taxon. Hill (1960), influenced by those authors, proposed a more complete taxonomic arrangement. More recently, only Hershkovitz (1990), Kobayashi (1995) and Anselmo (1997) performed taxonomic studies of Callicebus. Hershkovitz (1990) based in skull, skeleton morphology and pelage color, recognized 13 species with 25 subspecific taxa, divided among four groups, as listed in Table 1.
Kobayashi (1995) carried a phenetic analysis based on metric skull characters, besides cariotype, pelage coloration and geographic distribution of 23 species and subspecies (C. oenanthe, C. aureipalatti and C. coimbrai were not included; the last two had not been described at that time). He recognized five species groups (Table 1) and stated these groups are independent lineages since the rates of character differentiation were not significantly different among the nearest related groups. Among these groups, Kobayashi (1995) pointed out a great differentiation rate between personatus and torquatus, while donacophilus, cupreus, moloch appear more closely related. Concerning the pelage color pattern of the moloch group, Kobayashi considered donacophilus and personatus groups as “no contrasting pattern”, burnt yellow for donacophilus and blackish to yellowish for personatus; the cupreus group was defined as “weakly contrasting” and moloch and torquatus groups as “contrasting ventral surfaces” and “throat with white band”, respectively. Roosmalen et al. (2002) described two new species (C. stephennashi and C. bernhardi), and considered five species groups: 1. torquatus, 2. personatus, 3. moloch, 4. cupreus, 5. donacophilus.
The great individual and population color variation in Callicebus raises several doubts and, sometimes, misunderstanding about the taxonomy of this genus. Aquino et al. (2008) found two distinctive populations of Callicebus torquatus in northeast Peru. Although several characteristics such as the shape of the hair tuft on the throat (a characteristic of torquatus group), color tones on hands and the width of frontal band, seems to be different among those populations, the authors were not confident whether the two populations could be considered as different taxa or not. Heymann et al. (2002) also found problems with Callicebus phenotypical characterization, notably on the color of the hands. Moore (2009) tested the use of pelage color characters as diagnostic taxonomic markers across the geographic distribution of the Callicebus cupreus-group as an example. He found both a clinal variation along a geographic transect, as well as a localized intra-populational variation. He emphasizes that systematists should be careful while considering the relationship between intrapopulational variation and geographic distribution. In this article I present an analysis of the color pattern of all Callicebus specimens from the main Brazilian collections, in order to evaluate phenotypical polymorphism and the validity of these species using the color pattern of fur and hair as diagnosable characters.
Taxonomic status synopsis of Callicebus as presented by some authors and this work (modified from Roosmalen, 2002).
Material and methods
I examined 455 dry skins of 25 species from 136 localities belonging to the following collections: Museu de Zoologia da Universidade de São Paulo (MZUSP - 194 specimens); Museu Nacional do Rio de Janeiro (MNRJ - 97); Museu Paraense Emílio Goeldi (MPEG - 130); Instituto Nacional de Pesquisas da Amazônia (INPA - 10); Instituto Pau Brasil de História Natural (IPBHN - 10; Universidade de Brasília (UnB - 1) and Centro de Primatologia do Rio de Janeiro (CPRJ - 4). Appendix I lists the specimens together with geographic coordinates, label identification and a review of identification as found after this analysis. One specimen of C. pallescens and one of C. caligatus were studied alive in captivity. Material of Callicebus medemi, C. oenanthe, C. ollalae, C. modestus and C. auriepallati were not available so these were excluded from this study.
Distinctive characters among C. cupreus, C. caligatus and C. dubius.
Characters were chosen based on the pelage color of body parts or chromogenetic fields. Following Hershkovitz (1977), these are defined as any part of the pelage showing a particular color pattern from nearby areas, (for instance, the forearm, the back, one sub-apical band in a hair, etc), as shown in Figure 1. I could find chromogenetic fields characters only in pelage, not in hair, so the analysis focused on those. Each specimen was morphologically analyzed and assigned to different chromogenetic pattern groups by comparing the color pattern of 14 regions (shown in Figure 1, plus chest, belly and ventral surface of limbs), considering color tone variation as character states. This variation is due to the pigment present in hairs. Hershkovitz (1977) points out pheomelanin as the pigment responsible for yellows, browns and reds, depending on the amount of it deposited in the hair. Melanin is the pigment which gives black and gray colors to the hair. The analyses were performed by simple visual inspection, for example: when the character was crown with melanin pigment, states could be gray or black. Characters used in this study are listed in Table 2.
Collecting sites were plotted (Fig. 2) and compared with bibliography. Although almost all Callicebus species were included in this analysis (25 of 29 species), only the ones with taxonomic problems are discussed in this paper. Table 3 lists these species and the number of specimens analyzed.
Results and Discussion
1. C. moloch/ C. bernhardi
Pelage chromogenetic analysis shows C. moloch has great color tone variation on several chromogenetic fields, especially on the ventral surface, which ranges from yellow to reddish-brown. I could split the specimens into three phenotypes: “normal phenotype”, “red phenotype” and “light phenotype”. The “normal phenotype” is the commonest (84% of the sample) and has a cream forehead, crown (banded hair showing light bands broader than dark ones) flanks, dorsal surface of limbs, feet and hands; lower-back light brown with a slight brown stripe along the middle back, slightly darker than the flanks, not washed with brown or it has very little amount of this pigment. The middle portion of tail is very dark (from dark brown to black) and the tip lightening to very light brown or dirty white. Beard, chest, belly and ventral surface of limbs are light orange-brown, more pigmented at the tip of hairs.
The general color pattern of all specimens follows the description above, but specimens IPBHN 207, 208, 209 (loc. 52, Ig Almas, Rio Juruena, extreme north of Apiacás, MT); MZUSP 18956 (loc.53 - RO, Nova Colina Polonoroeste); MZUSP 18964, 20253, 20255, 20058, 20067 (loc.54 RO, Nova Brasília Polonoroeste); MPEG 21972 (loc. 112 - PA, Ig. do Patauá, Município de Itaituba); MPEG 22000 (loc. 113 - PA, Apui, BR-230 Humaitá-Itaituba km 17) have the ventral pelage extremely pheomelanized of a live reddish-brown. These represent what I called “red phenotype”. A third phenotype, called here “light phenotype” has ventral parts much lighter, sort of a lime-yellow (specimens MZUSP 5198 and 5200 from loc. 82 - AM, Bom Jardim, right margin of Amazonas River); MPEG 22014, 22015, 22016, 22017 (loc. 109 - PA, UHE Tucuruí, Tocantins River); MPEG 245 (loc. 95 - PA, São João do Araguaia); MPEG 246 (loc. 94 - PA, Alto Iriri River, Xingu).
Roosmalen et al. (2002) described C. bernhardi and identified specimens MPEG 22996, 22997 (locality 50 - BR km 150 Apis-Humaitá, right margin of Marmelos River, AM); MPEG 24590 and 24591 (locality 55 - Alta Floresta, MT) as belonging to this taxon. Paratypes of C. bernhardi (INPA 4029 and 4033; locality 57 - AM River Mariepauá left aff. River Madeira) show the same chromogenetic pattern as C. moloch, with identical chromogenetic fields. These specimens differ only in color tone and pigment amount on the ventral surface, exactly as seen in the “red phenotype”. In Roosmalen et al. (op. cit.), diagnostic characters that distinguish C. bernhardi of C. moloch are described as follows: “…by grayish forehead and crown, white ear tufts, and blackish tail with a distinct white pencil”. Actually, there is wide variation in forehead and crown color tone among all 183 specimens of the 3 phenotypes, from grayish to light red-brown, and the description above agrees perfectly with most specimens analyzed of “normal phenotype” as well.
Material used for this study.
Concerning the auricular tufts, none of 183 specimens of C. moloch (3 phenotypes) and those identified as C. bernhardi in INPA and MPEG that I could analyze, presented white auricular tufts (including C. bernhardi paratypes). Tails of all “red phenotype” specimens as well as C. bernhardi specimens are identical to C. moloch: black with a lighter tip. Drawings of C. moloch in Roosmalen et al. (2002) do not show a black tail and the whitish back of the hands, not matching all specimens analyzed. Thus, all specimens of the “normal phenotype”, “red phenotype”, “light phenotype” and those described as C. bernhardi show the same chromogenetic field pattern, differing, as mentioned, only in the amount of pigment (color tone) of the ventral surface.
Concerning the geographic distribution of C. moloch (all phenotypes), it is the broadest among all Callicebus species, occurring south of the Amazonas River, between the right margin of Madeira/Ji-Paraná Rivers to the left margin of Tocantins River. C. moloch is not found between the right margin of Aripuanã River and the left margin of Abacaxis River, where C. cinerascens is found (Noronha, et al. 2007). Callicebus moloch is found in Rondônia on both margins of the medium/upper Ji-Paraná River (Ferrari, et al. 2000), what is confirmed by specimens MZUSP 18956 (RO, Nova Colina Polonoroeste, right margin of Ji-Paraná River 10°48′S61°43′W, “red phenotype”; MZUSP 18964, 20253, 20255, 20058, 20067 (RO, Nova Brasília Polonoroeste, right margin of Ji-Paraná River- 10°56′S61°20′W “red phenotype”, and MPEG 19709, 19710, 19712, 19713 (Alvorada d'Oeste, BR 429 linha 64 km 87, left margin of Ji-Paraná River - 11°23′S62°18′W normal phenotype. Monção et. al. (2008) also assigned specimens they called C. bernhardi (here, “red phenotype”) to 90 km west of Alto Alegre dos Parecis (Chapada dos Parecis, Rondonia).
Roosmalen (2002) states that there is a gap in the range of Callicebus at the southern portion of this region, between Sucunduri/Juruena River and Tapajós River. I could not find any specimens in Brazilian museums from this region. Wide rivers such as the Juruena / Teles Pires / Tapajós are no barriers isolating the three phenotypes of C. moloch. Gascon et al. (2000) observed that wide rivers are not always obstacles to put apart small mammals and frogs as well.
Localities for C. bernhardi indicated by Roosmalen et al. (2002) are: 51 (AM, Comunidade de Nova Olinda, right margin of Aripuanã River, Novo Aripuanã - holotype, INPA 3929 only skeleton) and 57 (AM, Mariepauá River, right tributary of Madeira River - paratypes of C. bernhardi). Specimens MNRJ 2480 and 2481 (from AM, right margin of São João do Aripuanã River) presents “light phenotype” and this locality is only 30 km straight line from locality 51 and 60 km from locality 57, mentioned above, on the same bank of Aripuanã River. In the locality 109 (PA, UHE Tucuruí rio Tocantins) it is possible to find both “light and normal phenotype” as can be seen in specimens MPEG 21442, 21443, 22014, 22015, 22016, 22017, 22016 (normal phenotype) MPEG 22018 (light phenotype), one evidence of polymorphism. “Red phenotype” can be found far to the east from known localities of C. bernhardi. Specimens MPEG 21972 (locality 112- Ig. Patauá, Itaituba, PA), MPEG 22000 (BR 230 Itaituba, PA) and IPBHN 207, 208, 209 (locality 52- Ig. Almas, Juruena River, Apiacás, MT) are “red phenotype” (see Appendix I for coordinates). These localities are among others where phenotype can be normal phenotype or light phenotype, one more evidence of polymorphism.
One specimen from Alta Floresta (locality 55) MPEG 24590, label identificated as C. bernhardi, had its DNAmt sequenced and it is more similar to the sequence of IPBHN 207 (from Apiacás, MT), both “red phenotypes”. A phylogenetic analysis for Callicebus carried by me (to be published elsewhere) shows strong evidence for the three phenotypes of C. moloch to be considered a polymorphism of the same taxon. Also, C. bernhardi appears as sister group of C. moloch. It is possible to recognize a trend to a clinal variation along a east-west transect through the range of the species, with specimens from western localities showing more pigmented ventral parts (phenotype red) and specimens with lighter ventral parts (phenotype light) to the east. “Normal phenotype” is found throughout the range. Moore (2009) found similar results in C. cupreus. C. hoffmannsi showed similar south-north differences in ventral amount of pigments as can be seen bellow. Based on this, I suggest here C. bernhardi, Roosmalen et al. (2002), to be considered as a junior synonym of C. moloch.
2. C. hoffmannsi
Analysis of chromogenetic fields of C. hoffmannsi found two phenotypes differing only in the color tones of the ventral parts: hoffmannsi 1, yellow similar to that observed in typical C. moloch; and hoffmannsi 2 which looks a very light lime-yellow. Pattern hoffmannsi 2 is found north of pattern 1, the boundary between them set approximately by latitude 4°S (Itaituba, Para) (Fig. 2). Despite color differences and non-overlapping ranges, I could not find any geographic barrier or an ecological feature supporting the possibility that C. hoffmannsi should be split into two taxa. So, I consider these two phenotypes as polymorphisms of the same species until other evidence of speciation arises.
3. C. cupreus
Callicebus cupreus also shows three phenotypes: Phenotype 1: forehead and crown reddish-cream (agouti hair banded with light stripes broader than the dark ones). Back and nape almost concolor with crown. Lower back similar, but washed with brown. Tail as back; arms, legs, chest, belly and ventral surface of an intense reddish brown, sometimes orangish. Back of hands and feet are brown, not agouti. Phenotype 2: specimens MZUSP11831 and 11832 from Pauini, AM, have arms, legs, chest and ventral surfaces orangish. Phenotype 3 C. cupreus MZUSP7332 from Iquiri River, AM, holotype of C. cupreus acreanus and MZUSP5067 and 5068 from Santa Cruz do Eiru River have forehead and crown agouti-brown with black and cream, lighter than described for the phenotype 1, back as moloch and lower-back more brownish. Tail is dark-brown, gradually getting lighter to the tip, which is cream. Arms, legs, ventral surfaces and beard are dark reddish-brown, almost dark red.
Six specimens (MPEG 1587, 1588, 1605, 1608, 1609 and 1845) from Amazonas (Rio Javari, Estirão do Equador) are darker than the phenotype 3, described here. Phenotypes are distributed in four localities (Figure 2) that are inside the known distribution of C. cupreus and do not show a geographic pattern that could suggest an existence of more than one only taxon. As it was not possible to identify geographical limits that could indicate segregation among taxa, and it was not possible to perform a DNA analysis, definite considerations about the taxonomic status of C. cupreus must await, intra-specific color polymorphism being the best explanation for the observed pattern.
4. C. cupreus, C. caligatus and C. dubius
Grooves (2001) follows Hershkovitz (1990) in Callicebus taxonomy, but doubts him concerning some propositions. One of them considers C. caligatus, C. dubius and C. cupreus as synonyms. Roosmalen et al. (2002) described differences among these three species, considering all of them valid, a view I agree based on morphological grounds. All three show several distinctive characters, as pointed out by Roosmalen (2002) and revised here (shown in Table 2), such as the presence or absence of chromogenetic fields, e.g. frontal white and black stripes, tip of tail and white fingers.
C. bernhardi must be considered as a junior synonym of C. moloch, since the only difference between them is the amount of pigment in the hairs and it occurs in sympatry with C. moloch in several localiryes. C. hoffmannsii shows two phenotypes with parapatric ranges, but without any defined geographic barrier that could support their assignment as two different taxa. Phenotype variation in C. cupreus is polymorphic, and do not show a geographic pattern that could support the idea of splitting it in more than one taxon; Callicebus cupreus, C. dubius e C. caligatus are distinct species since they present several distinctive characters and allopatric ranges.
I would like to thank Dr. Paulo Nogueira Neto, my supervisor, for making all these analyses possible; to Dr. Renato Caparroz, Maraisa Lopes, Dr. Fábio Olmos, MSc. Cláudia Renata Madella, Dr. Erwin Palacios and other two anonymous reviewers who provided many valuable comments and constructive criticisms on this manuscript. Also, I thank all institutions which allowed me to access their collections, in the name of their very kind curators. I am very proud and thankful to Departamento de Zoologia da Universidade de São Paulo for accepting me for my doctorate thesis. I also thank to CAPES for financing my scholarship and trips which were necessary for the development of this project.
Collecting sites of all specimens analyzed. Label: Taxon indicated in label; Analysis = identification by the author of this article; Specimens = specimens' Number at collection; Listing numbers in bold are those cited in the map of Figure 2.