Literature dubius

Hershkovitz, 1988

Callicebus dubius

Member of the moloch group.

Remarks: The origin of C. dubius is problematic. Its distinctive characters, a mosaic of cupreus an caligatus, suggest hybridization between the sympatric species. Possible origins asa simple variable of C. caligatus as a subspecies of the same, or independently derived from the same prototype, are discussed below.

The origin of Callicebus dubius is dubious. Evolution of the frontal blaze in C. dubius seemingly parallels that of C. cupreus discolor and C. c. ornatus. It could have been begun with a few midfrontal hairs on a blackish agouti forehead, as in one of two specimens from Humaitá, Río Madeira. The whitish marking then expanded to a full blown transverse blaze, as in the second Humaitá specimen, a third specimen from Lago Mapixi, Río Purús, presumably opposite Lago do Aiapuá. A fifth specimen of unknown provenance is like the first Humaitá specimen. On the other hand, the blackish crown bordering the pale transverse band consistently distinguishes dubius from cupreus of the opposite bank of the Río Purús. Eumelanized cheiridia of dubius contrasts even more sharply with the pheomelanized cheiridia of all forms of C. cupreus.

The few whitish hairs in the blackish frontal field of the two aforementioned individuals of dubius is all that distinguishes the pair from C. calligatus. It might be assumed that forehead colouration, from completely blackish to whitish, is no more than a variable within caligatus. The variation, however, is neither age or sex related. It is a prominent adult display character of the sort that distinguishes species or subspecies such as cupreus from discolor, and many other species of monkeys from near relatives. C. dubius, however, cannot be treated as a subspecies of C. caligatus on geographical grounds. All modern distribution records indicate that the range of dubius may be confined to the basin between the east bank of the Río Purús and the west bank of the lower Madeira. The type locality, recorded as Lago do Aiapu, is on the west bank of the Purús where C. caligatus, C. cupreus, and C. torquatus are sympatric. More likely, the holotype of dubius was collected on the east bank of the Río Purús, opposite Lago do Aiapuá.

If C. dubius is not simply a scattered population of individual variables of C. caligatus, and if it is not a subspecies of caligatus because of putative sympatry, it may have originated independently. However, C. dubius is indistinguisable from caligatus except for the secondary derived frontal tuft or blaze, as in C. cupreus discolor. This combination, or mosaic, of characters suggests hybridization between individuals of a small mixed population of C. cupreus and C. caligatus that had been passively transferred by a river bend cutoff from west bank to east bank of the lower Río Purús. If interbreeding between the species followed, a hybrid generation was produced, became established, and dispersed throughout te basin between the lower Ríos Purús and Madeira. More distributional data and karyotypes are needed to help resolve the true mode of dubius speciation.

Hershkovitz, P. (1988) Origin, Speciation, and Distribution of South American Titi Monkeys, Genus Callicebus (Family Cebidae, Platyrrhini), by Philip Hershkovitz . Proceedings of the Academy of Natural Sciences of Philadelphia 140 (1): 240-272.

Hershkovitz, 1990

Callicebus dubius

Member of the moloch Group.

Synonyms: ?Callithrix caligata (von Pelzeln, 1883 – part); Callicebus caligatus (Thomas, 1908 – part); Callicebus cupreus caligatus (Hill, 1960 – part); Callicebus moloch cupreus (Hershkovitz, 1963 – part); Callicebus moloch (Napier, 1976 – part); Callicebus castaneoventris (Napier, 1976 – part); Callicebus dubius (Hershkovitz, 1988).

Type Locality: Said to be Lago do Aiapua, west bank lower Rio Purus. Distributional records and geographic relationships of Callicebus dubius indicate that the holotype more likely originated on the east bank of the lower Rio Purus, probably opposite Lago do Aiapua. The collector, Carl Lako, purchased from native hunters most of the specimens he sold to museums or dealers. The information he received regarding place and date of capture, usually days to months after the event, depended on the testimony of his agents. Measurements given on his labels are approximations in cm, some grossly inaccurate. Holotype in the Field museum on Natural History, Chicago.

Distribution: Between west bank of Rio Madeira and east bank of lower Rio Purus, Amazonas, Brazil.

Description: Buffy or whitish frontal tuft or transverse blaze present, crown anterior to ears blackish; sideburns, most of outer surface of forearms, and legs reddish; cheiridia blackish or reddish brown; skull essentially as in the moloch group, but with line between frontal bones about as long as straight line between parietals, palate across molars extremely wide.

Measurements: See publication.

Comparisons: Distinguished from Callicebus cupreus discolor, C. c. ornatus, and C. oenanthe by pronounced blackish coronal band bordering whitish frontal blaze and dominantly blackish or reddish brown cheiridia; from C. c. cupreus by frontal blaze and dark cheiridia; from C. caligatus by whitish frontal tuft or blaze; from all other species of Callicebus by one or more of the foregoing characters.

External Characters of Holotype: Forehead with pale buffy blaze, the hairs with narrow blackish bases and tips, radiating from centre, the whole bordered by a thin line of blackish hairs including superciliary vibrissae in front and sides and a broad blackish coronal band behind; remainder of crown brownish agouti, the lax hairs cresting against shorter blackish hairs in front and longer raised agouti nuchal hairs behind; hairs of nape, back, rump, and cover hairs of midback with 4 or 5 narrow pheomelanin bands, each alternating with a eumelanin band; sides of trunk like back but hairs longer, 5- to 6-banded; outer side of thighs and upper arms brownish agouti like back; lower arms and legs reddish, upper surface of tail dominantly blackish agouti on proximal third, mixed blackish and greyish agouti on remainder, pencilled tip missing, underside like upper but with base dominantly blackish agouti; blackish face naked except for fine buffy hairs surrounding lips and between nostrils; sideburns, sides of head, and beard uniformly deep reddish; hairs of sides directed forward and upward, of neck forward and laterally, the reddish coloration sharply contrasted with that of forehead and crown; hairs of throat, chest, belly, and inner side of limbs unbanded reddish or reddish brown with those of throat whorled; cheiridia dominantly blackish agouti; length of gular and pectoral glands combined about 6 or 7 cm; blackish ears with buffy agouti hairs on outer (medial) side, reddish brown on inner.

Variation: Distinction of C. dubius from C. caligatus is based on its pale frontal tuft or blaze.
This character, however, is tenuous. The blaze occupies nearly the entire forehead in the holotype and the Lago do Mapixi specimen. It is equally conspicuous in one of two from Humaita, Rio Madeira, (in the British Museum), but represented by a few whitish banded hairs in the second; blaze of so-called cotype of castaneoventris no better developed than that of second Humaita specimen with which it agrees in all other respects; blackish superciliary fringe absent or poorly defined; tail marbled or dominantly blackish for most of length, pencilled tip buffy, but in the Lago do Mapixi specimen terminal fifth dominantly buffy.

Taxonomy: Relationship between Callicebus dubius and C. caligatus recalls those between an odd specimen of Callicebus cupreus cupreus with an incipient pale frontal tuft and two odd specimens of C. cupreus discolor without frontal tuft or blaze. With exception noted, the normally blaze less C. c. cupreus and normally blazed C. c. discolor are each well defined allopatric subspecies. Callicebus dubius and C. caligatus likewise distinguishable, the one by presence and the other by absence of frontal tuft or blaze, but in this case may be sympatric. In general, the coloration of C. dubius appears to be a mosaic of that of C. cupreus and C. caligatus, suggesting that this species may be a hybrid of the other two. The hypothetical origin and possible relationship between C. dubius, C caligatus, and C. cupreus have been discussed elsewhere (Hershkovitz, 1988) and illustrated in this publication. In the original publication (Hershkovitz, 1988), the coloured figures of Callicebus dubius and Callicebus caligatus, but not the binomials, were transposed by the printer. The author was not shown proofs. Fortunately, the journal editor supplied 200 corrected figures for distribution with the reprints of the article. The promised corrigendum for volume 140 of the Proceedings of the Academy of Natural Sciences, Philadelphia, has not yet been honoured. Representatives of C. cupreus, C. caligatus, and C. torquatus are sympatric in the Lago do Aiapua region, on the left (west) bank of the Rio Purus. It is unlikely that a fourth species, C. dubius, occurs with them.

Specimens Examined: Total 5, all from Brazil. Amazonas: Humaita; “Lago Aiapua” (holotype of dubius); Lago Mapixi.

Hershkovitz, P. (1990). Titis, New World Monkeys of the genus Callicebus: A Preliminary Taxonomic Review. Fieldiana Zoology 55: 1-109.

Kobayashi, 1995

Callicebus dubius

Based on cranial measurements, the genus can be divided in five groups:

  • the donacophilus group (including modestus, olallae, d. donacophilus and d. pallescens)
  • the cupreus group (including caligatus, c. cupreus, c. discolor and c. ornatus)
  • the moloch group (including brunneus, h. hoffmannsi, h. baptista, moloch and cinerascens)
  • the personatus group (including p. personatus, p. nigrifrons, p. melanochir)
  • the torquatus group (including t. lucifer, t. lugens, t. medemi, t. regulus, t. purinus and t. torquatus).

The group position of C. dubius remains uncertain; C. oenanthe and C. barbarabrownae were not examined.

Kobayashi, S. (1995). A phylogenetic study of Titi Monkeys, Genus Callicebus, based on cranial measurements: 1. Phyletic groups of Callicebus. Primates 36(1): 101-120.

Groves, 2001

Callicebus cupreus

Synonyms: Callithrix cuprea (Spix, 1823); Callithrix caligata (Wagner, 1842); Callithrix discolor (I. Geoffroy and Deville, 1848); Callithrix castaneoventris (Gray, 1866); Callithrix cuprea leucometopus (Cabrera, 1900); Callicebus subrufus (1907); Callicebus ustofuscus (Elliot, 1907); Callicebus egeria (Thomas, 1908); Callicebus paenulatus (Elliot, 1909); Callicebus toppinii (Thomas, 1914); Callicebus cupreus napoleon (Lönnberg, 1922); Callicebus rutteri (Thomas, 1923); Callicebus cupreus acreanus (Vieira, 1952) and Callicebus dubius (Hershkovitz, 1988).

Distribution: South of the Napo-Solimoes, from the Rio Purus-Ituxi to the Andes; Hernandez-Camacho and Cooper (1976) mapped it as far north as the southern bank of the Rio Guamues, in extreme southern Colombia. A population on the Rio Sucusari, a lower left-bank tributary of Rio Napo, was reported by Brooks and Pando-Vasquez (1997).

Description: Hairs have a long maroon-brown base, a straw-coloured band, a black band, another straw band, and sometimes a black tip. Hands and feet red. Tail brindled (hairs have straw-coloured base, long blackish shaft, straw tip). Crown agouti, becoming black anteriorly for various distances, but including forehead; sideburns reddish or orange; a white brown band variably present. Underside sharply marked reddish or orange, this tone extending to sides of the neck and inner surface of limbs; hands and feet reddish to whitish.

Remarks: Hershkovitz (1990) recognized four different taxa here: C. cupreus cupreus, C. cupreus discolor, C. caligatus and C. dubius. The first two were said to be predominantly phaeomelanic, the second two more eumelanic; in C. c. cupreus and C. caligatus there is no frontal band or just a small, agouti median tuft; in C. c. discolor and C. dubius there is a variable developed white frontal blaze. The distributions of the four, taken as a group, are coterminous, but the two easterly forms have the frontal blaze whereas the two westerly ones are without it, so that at the very least there is a remarkable parallelism between phaeomelanic and eumalenic species in their geographical variation. I suggested (Groves, 1992) that this odd situation could be resolved if the eumelanic and phaeomelanic “species” are actually morphs of a singe species.

This hypothesis was tested by my examination of the skins in AMNH in 1997. It is corroborated; not only are eu- and phaeomelanic skins most readily interpreted as morphs of a single species, there is in fact very little difference between them at all. In skins identified as caligatus, the hair bases are redder, less brown than those labelled cupreus; the underside is more maroon, less foxy red; the red of the hands and feet is darker; the maroon of the cheeks is blackish rather than red.
Close reading of Hershkovitz (1990), indeed, suggests that even the geographic variation in presence or absence of the frontal blaze may not be so clear-cut. Thus, two series ascribed to C. c. discolor, collected by the Olallas at the mouth of the Rio Inuya (Rio Urumbamba) and Lagarto (upper Ucayali), were regarded as misplaced by Hershkovitz because they are on the “wrong” side of the Ucayali. He similarly regarded the localities of Ollala specimens of C. caligatus (Sarayacu and mouth of Rio Inuya). If the localities of these specimens are indeed incorrect, then an easterly trend in development of the frontal blaze is very marked; if not (if the Olallas correctly reported the localities), then blaze development ceases to have much geographic significance.
Finally, Hershkovitz (1990) also queried the locality of the type specimen of his C. dubius. If it originated from the east bank of the Rio Purus, as he hypothesized, then C. dubius is preserved as a distinct taxon with a small, river-bounded range; if from the west bank, as the label records, then the taxon has no identifiable separate distribution. From my findings and conclusions given here, I see no reason at all to query the locality as given.


Roosmalen et al., 2002

Callicebus dubius

Type locality: Said to be the bank of Lago Ayapuá, left bank of the lower Rio Purús, but since this would be impossible (hence it would have occurred in what Hershkovitz thought to be the distribution of both C. caligatus and C. cupreus), Hershkovitz (1990) assumed it originated from the right (east) bank of the Rio Purús, opposite Lago Ayapuá (coordinates approximately 04°20’S,
62°00’W). Native hunters must have supplied the animal collector Carl Lako with specimens from either side of the Rio Purús and from far upstream, since M. G. M. and T. van Roosmalen recently located the species along the Rio Seruiní on the right bank of the Rio Purús, south of the Rio Ituxí. Some specimens in the British Museum originated from the vicinity (probably southwest) of the town of Humaitá on the left bank of the Rio Madeira, the source of the Rio Ituxí. The holotype is an adult female, skin and skull, Field Museum of Natural History, Chicago, no. 38886, collected by Carl Lako in June 1931.

Distribution: South of the Rio Ituxí, or maybe even the Rio Mucuím, both right bank tributaries of the Rio Purús, east as far as the Rio Madeira south of the town of Humaitá, and west to the Rio Purús, southern limit unknown. The species might be parapatric with Callicebus stephennashi along the Rio Ituxí or maybe the Rio Mucuím in the northern part of its range, with Callicebus brunneus along the upper Rio Madeira in the southern or south-eastern part of its range, and with Callicebus cupreus along the Rio Purús in the west.

Description: Buffy or whitish frontal tuft, blaze, or transverse stripe, bordered below by blackish superciliary vibrissae forming narrow black line connecting the blackish ears, the crown brownish agouti; hairs of crown, nape, back, and rump with 4–5 narrow pheomelanin bands, each alternating with a eumelanin band; outer sides of thighs and upper arms brownish agouti like back; sideburns, sides of head, and beard deep reddish, outer surface of forearms and lower legs reddish; hairs of throat, chest, belly, and inner side of limbs not banded reddish to reddish brown; cheiridia blackish agouti, the fingers and toes contrasted pale or white; proximal one-third of tail red-brown agouti, as dorsum, rest of tail blackish, with a contrasted white pencil.
Distinguished from C. caligatus by its white or buffy frontal tuft or blaze, and lack of the black forehead and anterior part of crown; from C. cupreus, with which it is parapatric along the Rio Purús in the west by its white frontal tuft or blaze, and its white digits; from C. brunneus by its white or buffy frontal tuft or blaze and the contrasted white or buffy tail pencil; from C. stephennashi by its white or buffy frontal tuft or blaze and white digits only instead of entirely white cheiridia (as far as the wrists and ankles).

van Roosmalen, G.M.; van Roosmalen, T. and  Mittermeier, R.A. (2002). A taxonomic review of the titi monkeys, genus Callicebus Thomas 1903, with the description of two new species, Callicebus bernhardi and Callicebus stephennashi, from Brazilian Amazonia. Neotropical Primates 10(Suppl.): 1-52.

Rowe and Martinez, 2003

Callicebus dubius

More surveys will have to be conducted to find the exact distribution of C. brunneus, as well as whether C. dubius is actually present in Bolivia.


Röhe and Silva Jr., 2003

Callicebus dubius

Localities: Rio Mucuim 8° 42’02.4″S -64° 13’24.2″W; ‘Campina’ (INPA 5671)8° 39’10.5″S -64° 21’31.3″W; ‘Campina’ 8° 39’12.9″S -64° 21’28.0″W; ‘Trilha norte’ group 1/ 8° 39’10.0″S -64° 22’03.7″W; ‘Trilha norte’ group 2/ 8° 38’40.3″S -64° 22’04.4″W; ‘Curral’ 8° 38’54.3″S -64° 20’14.0″W; ‘Trilha sul’ 1/ 8° 40’34.9″S -64° 21’52.2″W; ‘Trilha sul’ 2/ 8° 39’26.9″S -64′ 19’21.7″W.

Distribution: The range of C. dubius is still uncertain. Hershkovitz (1990) assumed the type locality to be the right (east) bank of the Rio Purus, opposite to Lake Ayapuá. Two other species, Callicebus caligatus and Callicebus cupreus, occur in this area (van Roosmalen et al. 2002). Some specimens of C. dubius, deposited in the British Museum, were obtained in nearby Humaitá, a town on the left bank of the Rio Madeira. The holotype is an adult female (skin and skull), deposited in the Field Museum of Natural History, Chicago, number 38886, collected by Carl Lako in June 1931 (van Roosmalen et al. 2002). According to van Roosmalen and colleagues (2002) the distribution of C. dubius corresponds to the “south of the Rio Ituxí, or maybe even the Rio Mucuím, both right bank tributaries of the Rio Purus, eastern limit the Rio Madeira south of the town of Humaitá, and west to the Rio Purus, southern limit unknown”. This description is partially inconsistent with or at least not logically represented by the map in van Roosmalen et al. (2002) that shows the Rio de las Piedras (Bolivia) as the southern limit, with the Madre de Dios and Madeira defining the eastern limit of the species distribution. Rowe and Martinez (2003), however, have registered Callicebus brunneus in that region. Rowe and Martinez (2003) surveyed titi monkeys and found that their distribution in northern Bolivia is not consistent with the possible southern limit suggested by van Roosmalen et al. (2002) for C. dubius, but the distribution of C. brunneus coincides with reports by Anderson (1997) and Hershkovitz (1990). In addition, Robert Wallace (pers. comm.) has recorded a different species, which is not C. dubius, in the Department of Pando, Bolivia. The map in van Roosmalen et al. (2002) indicates the Rio Mucuim as eastern limit for C. dubius, although there is a sampling gap between this river and the Rio Ituxí. In this paper we provide additional data on the geographic distribution of C. dubius, confirming (a) its occurrence between the rivers Ituxi and Mucuim (see map) and (b) the latter river as the eastern limit. We also report an observation of individuals of this species crossing eastward towards the right bank of the Rio Mucuim using a man-made wooden bridge, and discuss the implications of this observation.

Remarks: C. dubius occupied areas of ‘Campinarana’ and ‘terra-firme’ open canopy forests covered by palms. On 26th April 2007 we observed several C. dubius during an intraspecific agonistic interaction on an unpaved road that crosses the Rio Mucuim, in the hydrographic basin of the Rio Purus. The animals were on the right bank of the Rio Mucuim, close to the wooden bridge that crosses this river. The event was observed, photographed, and reported by M. Hopkins and P. Assunção, botanical researchers from INPA, during the first Geoma Madeira-Purus Expedition.
This observation could imply a possible range expansion of C. dubius into the distributional range of C. stephennashi. Bridge crossing might be a more common event than expected as other primate species have also been observed exhibiting this behavior. These bridges over the rivers Mucuim and Água Branca do not exceed 30 and 15 m in length, respectively. These observations indicate that man-made structures may break down natural geographic barriers and thus interfere with biogeographic processes. The implications of such interference, e.g. potential for hybridization or displacement of one species by another, remain to be determined.

One voucher specimen (INPA 5671) of C. dubius was collected to guarantee species identification on the basis of external features (such as pelt colour and pattern) according to Hershkovitz (1988, 1990) and van Roosmalen et al. (2002).


Röhe and Silva jr., 2009

Callicebus dubius

Localities: within the Mucuim-Ituxi interfluvium, Callicebus dubius invades the right bank of the Rio Mucuim, which is in the range of Callicebus stephennashi (Record 1), and Callicebus dubius on the left bank of the Rio Mucuim (Records 2-8); Rio Mucuim 8°42’02.4″S – 64°13’24.2″W (= right bank of the Rio Mucuim); ‘Campina’ 8°39’10.5″S – 64°21’31.3″W; ‘Campina’8°39’12.9″S – 64°21’28.0″W; ‘Trilha norte’ group I 8°39’10.0″S – 64°22’03.7″W; ‘Trilha norte’ group II 8°38’40.3″S – 64°22’04.4″W; ‘Curral’ 8°38’54.3″S – 64°20’14.0″W; ‘Trilha sul’ I 8°40’34.9″S – 64°21’52.2″W; ‘Trilha sul’ II 8°39’26.9″S – 64°19’21.7″W.

Remarks: This confirms the distribution of this species between the Ituxi and Mucuim rivers, as suggested by van Roosmalen et al. (2002) but without proof through locality records. The ninth group was recorded on the right bank of the Rio Mucuim.

We observed several C. dubius during an intraspecific agonistic interaction on an unpaved road that crosses the Rio Mucuim, in the hydrographic basin of the Rio Purus. The animals were on the right bank of the Rio Mucuim, close to the wooden bridge that crosses this river. This observation could imply a possible range expansion of C. dubius into the distributional range of C. stephennashi. Bridge crossing might be a more common event thane xpected as other primate species have also been observed exhibiting this behavior.

Röhe, F. and Silva-jr, J.S. e (2009). Confirmation of Callicebus dubius (Pitheciidae) Distribution and Evidence of Invasion Into the Geographic Range of Callicebus stephennashi. Neotropical Primates 16(2): 71-73.

Auricchio, 2010

Callicebus dubius

Locality: AM Sao Paulo do Olivença, Mata Juratuba (03°57’S 68°57’W).

Description: Sideburns, sides of head and beard deep red; Forehead with white transversal frontal band, with a fine black line of superciliar vibrissae which connects the blackish ears; Crown, nape and back brownish agouti, hairs with 4-5 pheomelanic bands, each alternated with eumelanic band; Lower back reddish-brown-agouti, brownish agouti; hairs with 4-5 pheomelanic bands, each alternated with eumelanic band; External surface of fore legs and forearms reddish; Back of hands blackish agouti; Fingers and back of feet contrasting white; Base of tail reddish-brown–agouti; Middle of tail blackish; Tip of tail with contrasting white brush; Hairs of throat blackish agouti; chest, belly and ventral surface of legs and arms reddish or reddish-brown, not banded.

Remarks: Groves (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 et al. (2002) and revised here, such as the presence or absence of chromogenetic fields, e.g. frontal white and black stripes, tip of tail and white fingers.

Auricchio, P. (2010). A morphological analysis of some species of Callicebus. Neotropical Primates 17(2): 47-58.

Mercado and Wallace, 2010

Callicebus dubius

Remarks: Hershkovitz (1990) proposed that the species that can be found in the Pando Department of Bolivia is C. brunneus. However, van Roosmalen et al. (2002) classify this species as C. dubius, although they lack the white frontal band (characteristic of C. dubius). Furthermore, the tail doesn’t seem to be as white as in the drawing of C. brunneus by Stephen Nash in van Roosmalen (2002), but more brown reddish with a white tip (Rowe and Martinez, 2003). At the same time, when comparing specimens of C. brunneus collected in Brazil with a specimen collected en Chivé above the Madre de Dios River, on the border of the Pando and La Paz departments, one observes that these present a colouration different from the specimens from Brazil (Wallace et al., 2009; pers. com. with Robert Wallace). Here we prefer to identify them as Callicebus sp., until there is confirmation on the taxonomic identification.