The excitingly beautiful Fairy-Bluebirds are officially a small family of only two species, the Philippine Fairy-Bluebird (Irena cyanogastra) and the Asian Fairy-Bluebird (Irena puella), both including a number of subspecies.  

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Following a study from 2012 [1], however, there appear to exist eight species.:  

Andaman Fairy-Bluebird (Irena andamanica Abdulali) (formerly Irena puella ssp. andamanica Abdulali)  

Indonesian Fairy-Bluebird (Irena crinigera Sharpe) (formerly Irena puella ssp. crinigera Sharpe)  

Philippine Fairy-Bluebird (Irena cyanogstra Vigors) (formerly Irena cyanogastra ssp. cyanogastra Vigors)  

Ella’s Philippine Fairy-Bluebird (Irena ellae Steere) (formerly Irena cyanogastra ssp. ellae Steere)  

Hoogstral’s Philippine Fairy-Bluebird (Irena hoogstraali Rand) (formerly Irena cyanogastra ssp. hoogstraaliRand)  

Black-shouldered Philippine Fairy-Bluebird (Irena melanochlamys Sharpe) (formerly Irena cyanogastra ssp. melanochlamys Sharpe; but – was not included in this study!)  

Asian Fairy-Bluebird (Irena puella (Latham)), including three subspecies:  Irena puella ssp. malayensis F. Moore Irena puella ssp. puella (Latham) Irena puella ssp. turcosa Walden  

Palawan Fairy-Bluebird (Irena tweeddalei Sharpe) (formerly Irena puella ssp. tweeddalei Sharpe)  

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It is very interesting that most of these ‘new’ species were originally described as distinct species.  

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update:

The Palawan Fairy-Bluebird is now officially considered a full species and is included as such in the HBW Checklist of 2016. [2]  

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References:  

[1] Maria Moltesen; Martin Irestedt; Jon Fjeldså, Per G. P. Ericson, Knud A. Jønsson: Molecular phylogeny of Chloropsidae and Irenidae – Cryptic species and biogeography. Molecular Phylogenetics and Evolution 65: 903-914. 2012 
[2] Illustrated Checklist of the Birds of the World. Lynx Edicions; Ill edition Vol. 1 & 2. 2014/2017  

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edited: 17.09.2018