For the geometer moth

Geometer moth

The geometer moths or Geometridae are a family of the order Lepidoptera...

 genera Hypsipetes and Ypsipetes, see Hydriomena

Hydriomena

Hydriomena is a genus of moth in the family Geometridae.-Species:* Hydriomena albifasciata * Hydriomena albimontanata McDunnough, 1939* Hydriomena arizonata Barnes & McDunnough, 1917* Hydriomena barnesata Swett, 1909...

.

Hypsipetes is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of bulbul

Bulbul

Bulbuls are a family, Pycnonotidae, of medium-sized passerine songbirds. Many forest species are known as greenbuls. The family is distributed across most of Africa and into the Middle East, tropical Asia to Indonesia, and north as far as Japan. A few insular species occur on the tropical islands...

s, songbird

Songbird

A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...

s in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Pycnonotidae. Most of its species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 birds occur in tropical forests around the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

. But while the genus is quite diverse in the Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

 region at the western end of its range it does not reach the Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

n mainland.

Most Hypsipetes bulbuls are dark greyish birds with range or red bills and feet. The feathers on toip of the head are slightly elongated and usually black, and can be erected to form a short and wispy crest.

Species, systematics and taxonomy

The following species are provisionally placed here:

• Philippine Bulbul
  Philippine Bulbul
  The Philippine Bulbul is a songbird species in the bulbul family . It is often placed in the genus Ixos, but is better retained in Hypsipetes as long as this is not entirely merged into Ixos, as it is quite closely related to the type species of Hypsipetes, the Black Bulbul The Philippine Bulbul...
  
  , Hypsipetes philippinus
• Madagascar Bulbul
  Madagascar Bulbul
  The Malagasy Bulbul , also known as the Madagascar Bulbul, is a species of songbird in the Pycnonotidae family. It is found on the Comoros, Madagascar, Mayotte, and the Seychelles.-References:...
  
  , Hypsipetes madagascariensis
• Nicobar Bulbul
  Nicobar Bulbul
  Found only on the Nicobar Islands of India, the Nicobar Bulbul is a songbird species in the bulbul family . Its scientific name is Hypsipetes virescens as long as Ixos is recognized as a distinct genus....
  
  , Hypsipetes virescens (or H. nicobariensis, see below)
• Comoro Bulbul
  Comoro Bulbul
  The Comoro Bulbul is a species of songbird in the Pycnonotidae family.It is found in Comoros and Mayotte.Its natural habitat is subtropical or tropical moist montanes.-References:...
  
  , Hypsipetes parvirostris
• White-headed Bulbul
  White-headed Bulbul
  The White-headed Bulbul is a songbird species in the bulbul family . It is the sometimes separated in a monotypic genus Cerasophila ....
  
  , Hypsipetes thompsoni (sometimes in Cerasophila)
• Black Bulbul
  Black Bulbul
  The Black Bulbul , also known as the Himalayan Black Bulbul, Asian Black Bulbul or Square-tailed Bulbul, is a member of the bulbul family of passerine birds. It is found in southern Asia from India east to southern China. It is the type species of the genus Hypsipetes, established by Nicholas...
  
  , Hypsipetes leucocephalus (type species
  Type species
  In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
  
  )
  • Square-tailed Black Bulbul, Hypsipetes (leucocephalus) ganeesa
• Seychelles Bulbul
  Seychelles Bulbul
  The Seychelles Bulbul, Hypsipetes crassirostris, is a member of the bulbul family of passerine birds. The species is related to the Comoro Bulbul. It is a common endemic species of the Seychelles, breeding on Mahé, Praslin, La Digue and Silhouette as well as some smaller islands...
  
  , Hypsipetes crassirostris
• Mauritius Bulbul
  Mauritius Bulbul
  The Mauritius Bulbul , also known as Mauritius Black Bulbul, is a songbird endemic to Mauritius. Formerly, it was included in H. borbonicus as subspecies olivaceus....
  
  , Hypsipetes olivaceus
• Réunion Bulbul
  Réunion Bulbul
  The Réunion Bulbul , also known as Olivaceous Bulbul, is a passerine endemic to Réunion. Formerly, the Mauritius Bulbul was included here as subspecies olivaceus, but nowadays H. borbonicus is considered monotypic.-Description:It looks similar to the Mauritius Bulbul but with 22 cm it is...
  
  , Hypsipetes borbonicus

Systematics and taxonomy

The Mountain Bulbul

Mountain Bulbul

The Mountain Bulbul is a songbird species in the bulbul family . It is often placed in Hypsipetes, but seems to be closer to the type species of the genus Ixos, the Sunda Bulbul or Green-winged Bulbul...

 and Sunda Bulbul

Sunda Bulbul

The Sunda Bulbul or Green-winged Bulbul is a songbird species in the bulbul family . It is the type species of the genus Ixos....

 – formerly H. mcclellandii and H. virescens – are provisionally placed in Ixos

Ixos

Ixos is a songbird genus in the bulbul family, Pycnonotidae. It provisionally contains the following species:* Yellowish Bulbul, Ixos everetti* Streaked Bulbul, Ixos malaccensis...

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

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the 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

Hemixos

Hemixos is a songbird genus in the bulbul family, Pycnonotidae. Established by Edward Blyth in 1845 for the newly-discovered Ashy Bulbul Hemixos is a songbird genus in the bulbul family, Pycnonotidae. Established by Edward Blyth in 1845 for the newly-discovered Ashy Bulbul Hemixos is a songbird...

, Iole

Iole (genus)

Iole is a genus of bulbuls, songbirds in the family Pycnonotidae. They are native to tropical eastern Asia, from India to China and south through Southeast Asia to northern Indonesia.It includes the following species:* Olive Bulbul, Iole virescens...

, 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

Lumpers and splitters

Lumping and splitting refers to a well-known problem in any discipline which has to place individual examples into rigorously defined categories. The lumper/splitter problem occurs when there is the need to create classifications and assign examples to them, for example schools of literature,...

 however, since Alophoixus

Alophoixus

Alophoixus is a genus of songbird in the Pycnonotidae family. All the species occur in southeast Asia.It contains the following species:* Finsch's Bulbul * White-throated Bulbul...

and Setornis cannot be excluded from the "Hypsipetes group", and an all-out merge would turn the resultant "genus" into an ill-defined "wastebin taxon

Wastebin taxon

Wastebasket taxon is a term used in some taxonomic circles to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by their lack of one or more distinct character states or by their not belonging to one or more other taxa...

". The erroneous inclusion of I. virescens in Hypsipetes has caused the Nicobar Bulbul

Nicobar Bulbul

Found only on the Nicobar Islands of India, the Nicobar Bulbul is a songbird species in the bulbul family . Its scientific name is Hypsipetes virescens as long as Ixos is recognized as a distinct genus....

 to be listed under its invalid junior synonym H. nicobariensis rather than the valid names H. virescens or I. nicobariensis.

The Philippine Bulbul on the other hand seems to be closer to the Black Bulbul than to the Mountain Bulbul, and may in fact be correctly placed in Hypsipetes; some other species presently placed in Ixos – the Sulphur-bellied Bulbul

Sulphur-bellied Bulbul

The Sulphur-bellied Bulbul is a songbird species in the bulbul family .It is one of the species of Ixos that might warrant inclusion in the genus Hypsipetes – as long as this is kept separate from Ixos – as it may be a close relative of the Philippine Bulbul The Sulphur-bellied Bulbul...

, Zamboanga Bulbul

Zamboanga Bulbul

The Zamboanga Bulbul is a songbird species in the bulbul family .It is one of the species of Ixos that might warrant inclusion in the genus Hypsipetes – as long as this is kept separate from Ixos – as it may be a close relative of the Philippine Bulbul The Zamboanga Bulbul (Ixos...

 and Streak-breasted Bulbul

Streak-breasted Bulbul

The Streak-breasted Bulbul or Mottle-breasted Bulbul is a songbird species in the bulbul family ....

 (I. palawanensis, I. rufigularis and I. siquijorensis, respectively) – might also belong here. For as it seems, Ixos is paraphyletic with respect to its relatives, and though too few species have been studied, it may well be that like other species of Ixos (but not I. virescens) do belong in Hypsipetes after all. Alternatively, the Streaked Bulbul

Streaked Bulbul

The Streaked Bulbul is a songbird species in the bulbul family . Depending on whether it is or isn't a particularly close relative of the type species of the genus Ixos, the Sunda Bulbul or Green-winged Bulbul , it might belong in a new genus.What is presently known is that some Ixos species are...

 (I. malaccensis) and perhaps others which seem closer to the Hemixos

Hemixos

Hemixos is a songbird genus in the bulbul family, Pycnonotidae. Established by Edward Blyth in 1845 for the newly-discovered Ashy Bulbul Hemixos is a songbird genus in the bulbul family, Pycnonotidae. Established by Edward Blyth in 1845 for the newly-discovered Ashy Bulbul Hemixos is a songbird...

lineage might be included there or separated as a distinct genus, and Hypsipetes (and probably Microscelis as well) merged with the core of Ixos under the latter name.