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http://orchidspecies.com/orphotdir/rhynchostretusa.jpg
IOSPE PHOTOS

Rhynchostylis retusa is comparable to Rhynchostylis gigantea in coloration.
Flower Size 3/4" [2 cm]

Synonyms:
*Epidendrum retusum L. 1753
Aerides retusum [L.] Sw. 1799
Limodorum retusum Sw. 1799
Epidendrum indicum Poir. 1810
Aerides undulatum Sm. 1819
Aerides spicatum D. Don 1825
Epidendrum hippium Buch.-Ham. ex D.Don 1825
Saccolabium guttatum Lindley 1828
Sarcanthus guttatus Lindl. 1831
Aerides guttatum Roxb. 1832
Saccolabium spicatum (D.Don) Lindl. 1833
Orchis lanigera Blanco 1837
Saccolabium blumei Lindley 1841
Saccolabium macrostachyum Lindl. 1841
Saccolabium retusum Voight 1845
Saccolabium rheedii Wight 1852
Rhynchostylis guttata Rchb.f 1854
Rhynchostylis violacea Rchb.f. 1854
Saccolabium violaceum Rchb.f. 1854
Saccolabium garwalicum Lindley 1859
Rhynchostylis garwalica Rchb.f. 1864
Rhynchostylis gurwalica Rchb.f. 1864
Saccolabium heathii Hort. 1885
Gastrochilus blumei (Lindl.) Kuntze 1891
Gastrochilus garwalicus (Lindl.) Kuntze 1891
Gastrochilus retusus (L.) Kuntze 1891
Gastrochilus rheedei (Wight) Kuntze 1891
Gastrochilus spicatus (D.Don) Kuntze 1891
Gastrochilus violaceus (Rchb.f.) Kuntze 1891
Anota violacea (Rchb.f.) Schltr. 1914

Rhynchostylis praemorsa has smaller flowers to Rhynchostylis retusa and coloration and markings are different. And it is endemic to Philippines whereas Rhynchostylis retusa and Rhynchostylis gigantea are only indigenous species of the Philippines but widespread over the Malesian Bio-Geographical Region.
Flower Size 3/5" [1.5 cm]

Synonyms:
Aerides praemorsa Wilde. 1805
Gastrochilus praemorsus (Willd.) Kuntze 1891
Saccolabium praemorsum Lindley 1833