|The mountain bulbul (I. mcclellandii) is provisionally placed in Ixos, until its relationships are resolved.|
|4 species, but see text|
Taxonomy and systematics
The mountain bulbul and Sunda bulbul – formerly H. mcclellandii and H. virescens – are provisionally placed in Ixos until the genus limits in bulbuls are firmly established. They are often included in Hypsipetes but this is an old error that was promoted in modern times by the Sibley taxonomy. In fact, I. virescens is the type species of Ixos, and though some sources advocate a complete merger of the two genera – and even the entire "Hypsipetes group" of bulbuls, which also includes Hemixos, Iole, Microscelis and Tricholestes –, being the oldest genus name Ixos would apply to all of them, rather than Hypsipetes as is often believed.
The most drastic course hardly appropriate however, since Alophoixus and Setornis cannot be excluded from the "Hypsipetes group", and an all-out merge would turn the resultant "genus" Ixos into an ill-defined "wastebin taxon". The erroneous inclusion of I. virescens in Hypsipetes has caused the Nicobar bulbul to be listed under its invalid junior synonym H. nicobariensis rather than the valid names H. virescens or I. nicobariensis.
The streaked bulbul, meanwhile, seems to be closer to Hemixos and perhaps Iole and maybe the hook-billed bulbul (Setornis criniger) than to Hypsipetes. Thus, given the lack of study of the Sunda bulbul's affiliations, Ixos might eventually be reduced to the core group around I. virescens and kept well distinct from Hypsipetes. Or it may be that some species (such as I. malaccensis) will be split off into a distinct genus (for which no scientific name exists yet), while Hypsipetes is merged into the core group of Ixos.
There are four extant species in the family Ixos:
- Nicobar bulbul (Ixos nicobariensis)
- Mountain bulbul (Ixos mcclellandii)
- Streaked bulbul (Ixos malaccensis)
- Sunda bulbul (Ixos virescens) (the type species)
Formerly, some authorities also considered the following species (or subspecies) as species within the genus Ixos:
- Cream-striped bulbul (as Ixos leucogrammicus)
- Spot-necked bulbul (as Ixos tympanistrigus)
- Grey-headed bulbul (as Ixos Fisquetti)
- Scaly-breasted bulbul (as Ixos squamatus)
- Red-whiskered bulbul (pyrrhotis) (as Ixos pyrrhotis)
- Red-whiskered bulbul (emeria) (as Ixos emeria)
- Chinese red-whiskered bulbul (as Ixos monticola)
- Brown-breasted bulbul (andersoni) (as Ixus Andersoni)
- Light-vented bulbul (hainanus) (as Ixus hainanus)
- Gregory (2000), Pasquet et al. (2001), Moyle & Marks (2006)
- Pasquet et al. (2001), Moyle & Marks (2006)
- "Bulbuls « IOC World Bird List". www.worldbirdnames.org. Retrieved 2017-03-10.
- "Pycnonotus leucogrammicus - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-08.
- "Pycnonotus tympanistrigus - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-08.
- Eydoux F, L FASouleyet (1841). Voyage Autour du Monde sur la Corvette La Bonite. Paris: Arthus Bertrand. pp. 86–88.
- "Pycnonotus squamatus - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-12.
- "Pycnonotus jocosus pyrrhotis - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-12.
- Giebel, Christoph (1877-01-01). Thesaurus Ornithologiae: bd. Pachycephala-Zosterops. Brockhaus.
- "Pycnonotus jocosus monticola - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-12.
- "Pycnonotus xanthorrhous andersoni - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-13.
- "Pycnonotus sinensis hainanus - Avibase". avibase.bsc-eoc.org. Retrieved 2017-03-13.
- Gregory, Steven M. (2000): Nomenclature of the Hypsipetes Bulbuls (Pycnonotidae). Forktail 16: 164-166. PDF fulltext
- Moyle, Robert G. & Marks, Ben D. (2006): Phylogenetic relationships of the bulbuls (Aves: Pycnonotidae) based on mitochondrial and nuclear DNA sequence data. Mol. Phylogenet. Evol. 40(3): 687-695. doi:10.1016/j.ympev.2006.04.015 (HTML abstract)
- Pasquet, Éric; Han, Lian-Xian; Khobkhet, Obhas & Cibois, Alice (2001): Towards a molecular systematics of the genus Criniger, and a preliminary phylogeny of the bulbuls (Aves, Passeriformes, Pycnonotidae). Zoosystema 23(4): 857-863. PDF fulltext