Hylobates Illiger, 1811

Caspar, Kai R & Yi, Yoonjung, 2022, Hylobates moloch (Primates: Hylobatidae), Mammalian Species 54 (1021), pp. 1-19 : 1-2

Hylobates Illiger, 1811

Homo : Linnaeus, 1771:521. Part, not Homo Linnaeus, 1758 .

Simia : Schreber, 1775:66, pl.III. Part, not Simia Linnaeus, 1758 , an unavailable name ( International Commission on Zoological Nomenclature 1929, Opinion 114).

Gibbon Zimmermann, 1777:405. Type species Homo lar Linnaeus, 1771 (= Hylobates lar ( Linnaeus, 1771)) , by monotypy. Unavailable name ( International Commission on Zoological Nomenclature 1954, Opinion 257).

Pithecus : Latreille, 1804:276. Part, not Pithecus Geoffroy Saint-Hilaire and Cuvier, 1795 , an unavailable name ( International Commission on Zoological Nomenclature 1929, Opinion 114).

Hylobates Illiger, 1811:67 . Type species Homo lar Linnaeus, 1771 , by monotypy.

Satyrus Oken, 1816:1225 . No type species designated. Unavailable name ( International Commission on Zoological Nomenclature 1956, Opinion, 417); preoccupied by Satyra Meigen, 1803 , a genus of Diptera .

Laratus Gray, 1821:297 . Type species Homo lar Linnaeus, 1771 .

Cheiron Burnett, 1828:307 . No type species designated.

Hilobates Harlan, 1834:52 . Incorrect subsequent spelling of Hylobates Illiger, 1811 .

Hybolates Geoffroy Saint-Hilaire, 1834:31. Incorrect subsequent spelling of Hylobates Illiger, 1811 .

Brachiopithecus Sénéchal, 1839:428 . Part. No type species designated.

Methylobates Ameghino, 1884:479 . Part. No type species designated.

Brachitanytes Schultz, 1932:369 . Type species Symphalangus klossii, Miller, 1903 (= Hylobates klossii ( Miller, 1903)) by original designation.

Loratus Groves in Wilson and Reeder, 1993. Incorrect subse- CONTEXT AND CONTENT. Order Primates , suborder Haplorrhini , infraorder Simiiformes , parvorder Catarrhini , superfamily Hominoidea , family Hylobatidae , genus Hylobates . Hylobates is polytypic, with nine extant species being commonly recognized ( Chivers et al. 2013; Roos 2016): H. abbotti , H. agilis , H. albibarbis , H. funereus , H. klossii , H. lar , H. moloch , H. muelleri , H. pileatus . The Bornean species H. abbotti and H. funereus , which have been suggested to be distinct from H. muelleri ( Thinh et al. 2010) , remain insufficiently studied so that their current taxonomic status is not yet convincingly justified ( Roos 2016). The following key is based on adult morphological traits, primarily coat color, as described by Geissmann (1995) and Groves (1972, 2001), as well as selected song characteristics (Geissmann 1995). Expression of facial ornaments might be reduced in senile animals (Geissmann 1995). The presence of sexual dichromatism, ontogenetic changes in fur color, and great intraspecific variability in pelage coloration in some taxa can notably complicate the diagnosis of some Hylobates species based on physical characteristics alone.

1. Both sexes jet black; small, sparsely haired throat sack present. Distribution: Mentawai islands west of Sumatra ... ….................................................................……… H. klossii

Pelage not pure black, no throat sack present.….....................2

2. Pelage sexually dichromatic, both sexes with white hands and feet, males black with white genital tuft, face ring, and a black cap typically framed by white to gray hair; females creamy white to gray with black cap and chest. Distribution: Eastern Thailand and western Cambodia …….........…...… H. pileatus

Pelage not sexually dichrozmatic (except facial ornaments), if color phases present, then unrelated to sex…..................3

3. Hands and feet always white; white face ring usually well developed (more so in males than in females). Light (cream-colored) and dark (brown to black) color phases in continental populations, invariably light brown on Sumatra. Distribution: Central Indochina, Malayan Peninsula, northern Sumatra (Aceh)…....................................................................… H. lar

Hands and feet never white...............................................….4

4. Pelage silvery gray, often with wooly texture. Light face ring often incomplete with distinct white beard on chin; dark cap at least in traces present and often distinct. Primitive molar morphology conforming to hominoid ground pattern. Distribution: West Java.…..................................… H. moloch

Pelage not silvery gray, molar morphology derived, no chin beard but with light brow band…..................………….5

5. Hair over ears markedly elongated, genital tuft in males short and dark. Usually no light beards in either sex. Female song climax with sequence of fast bubbling notes….............……6 Hair over ears not strongly elongated, male genital tuft prominent. Light beards at least present in most males. Female song climax consists of long notes……..................…....8

6. Pelage mousy gray to brownish with face ring reduced to a white brow streak and no chin beard. Dark cap weakly expressed if at all, hands not darkened. Distribution: West Borneo north of the Kapuas river……........……… H. abbotti

Pelage brown with contrasting dark ventrum and cap………7

7. Hands or at least digits darker than limbs. Distribution: South eastern Borneo, east of the Barito river………….….........................................……. H. muelleri

Hand same color or lighter than limbs. Distribution: Northern Borneo, north to the Mahakam river..……… H. funereus

8. Large light cheek patches and contrastingly colored pelage in both sexes, dorsum light brown to golden, cap and ventral portions of rump and limps dark brown. Distribution: Southern Borneo between the rivers Kapuas and Barito….…................................................…… H. albibarbis

Pelage highly variable in color, ranging from creamy over brown to black, ventrum might be darkened or same as back. Face ring variably expressed, sometimes only supraciliary portion present. Males often with light cheek patches that are lacking in females. Dorsoventral contrast is weaker and the face ring in adults, especially in the cheek region, less prominent than in H. albibarbis . Distribution: Sumatra, south of Aceh, smaller zone of occurrence on the Malay Peninsula, roughly at the boarder of Thailand and Malaysia.......................……..… H. agilis