Abstract. DELFORGE, P. - Contribution to the knowledge of the Orchids of the island of Kea (Western Cyclades, Greece) [Natural. belges 92 (Orchid. 24): 124-201].
After a presentation of the tectonics, the geology, the geomorphology, the vegetation, the history, and the human impact on the landscape of the island of Kea, a review of the past and present studies and research about its orchids is made. It appears that 18 orchids species were known for Kea before 2011 (Table 1). Research in Kea in March and April 2011 has revealed 26 orchid species for the island, bringing their number up to 29 (Table 1). Among the 29 species known at present for the island, 3, not seen in 2011, are sporadic or extinct (Neotinea maculata, Ophrys aesculapii, and Orchis provincialis), and 4 are represented in 2011 by one or few grouped individuals (Ophrys attica, O. speculum, Orchis italica, and Serapias parviflora). Two species, Serapias orientalis var. sennii and S. vomeracea, are present in only 2/130 squares of 1 km × 1 km. A discussion is made for each species observed or listed in the island of Kea, following order and nomenclature used in DELFORGE (2006a, 2009a, 2010b, 2012).
The genus Dactylorhiza is represented only by D. romana (very local, first mention for Kea).
The genus Serapias is species-rich in the island and comprises 5 species and one interspecific hybrid. (1) S. parviflora is extremely local (first mention for Kea), (2) S. bergonii widespread (3) S. vomeracea extremely local, (4) S. orientalis var. sennii extremely local, first mention of S. orientalis for Kea, and (5) S. lingua local.
All of the Anacamptis pyramidalis seen in 2011 belong to A. pyramidalis var. brachystachys, very local.
The former genus Orchis s.l. is represented in Kea by 8 species belonging to 5 genus:
a.- Orchis s. str. with (1) O. italica (extremely local, only a group of 6 individuals seen on 1 site in 2011, first mention for Kea), (2) O. provincialis (extremely local, seen in 1991, not confirmed in 2011, probably extinct), (3) O. quadripunctata (extremely local);
b.- Neotinea with (4) N. maculata (extremely local, seen one time in 1968, not confirmed in 1991 and 2011, probably extinct), (5) N. lactea (rather widespread),
c.- Herorchis with (6) H. boryi  (extremely local),
d.- Anteriorchis with (7) A. fragrans (very local, first mention for Kea),
e.- Vermeulenia with (8) V. papilionacea var. aegaea (local, with 2 quite different waves of flowering).
The genus Ophrys is represented by 14 species in Kea.
The sectio Pseudophrys GODFERY comprises 7 species in the island which belong to 5 species groups:
a.- the Ophrys iricolor group with (1) O. iricolor (local);
b.- the Ophrys funerea group with (2) O. leucadica (local, previously recorded as O. nigroaenea fusca);
c.- the Ophrys attaviria group with (3) O. parosica var. parosica (very local, first mention for Kea) and (4) O. pelinaea (extremely local, first mention for the Cyclades);
d.- the Ophrys lutea group with (5) O. sicula (very widespread), (6) O. phryganae (very local, first mention for Kea);
e.- the Ophrys omegaifera group with (7) O. omegaifera (very local).
The section Ophrys (= Euophrys GODFERY nom. nudum) in Kea comprises 7 species which belong to 4 species groups:
a.- the Ophrys speculum group with (1) O. speculum var. orientalis (extremely local, only a group of 3 individuals seen on 1 site in 2011, first mention for Kea, second for the Cyclades);
b.- the Ophrys tenthredinifera group with (2) O. bombyliflora (widespread, with medium-sized flowers), (3) the large-flowered O. leochroma (rather widespread, previously recorded as O. tenthredinifera);
c.- the Ophrys umbilicata group with (4) O. attica (extremely local, 3 individuals seen in 1991, only 1 in 2011);
d.- the Ophrys mammosa group with (5) O. ferrum-equinum (rather widespread, with not very varied flowers: majority of f. ferrum-equinum and some individuals of f. subtriloba), (6) probably O. icariensis (very local, previously recorded as O. ferrum-equinum Kea type), (7) O. aesculapii (one dot in a distribution map published by KALOPISSIS 1988 without references; species not seen in 1991 and 2011).
A list of 29 species and 1 hybrid, and 31 distribution maps, based on the presence in 130 utmwgs84 squares of 1 km × 1 km, are provided as well as a list of 196 sites prospected during the spring 2011, from March 29 to April 17.

Key-Words: Flora of Greece, flora of Aegean, flora of Cyclades, flora of Kea (= Tzia); Orchidaceae, Anacamptis pyramidalis var. brachystachys, Anteriorchis fragrans, Dactylorhiza romana, Herorchis boryi, Neotinea lactea, N. maculata, Ophrys aesculapii, O. attica, O. bombyliflora, O. ferrum-equinum, O. icariensis, O. iricolor, O. leochroma, O. leucadica, O. omegaifera, O. parosica, O. pelinaea, O. phryganae, O. sicula, O. speculum var. orientalis, Orchis italica, O. provincialis, O. quadripunctata, Serapias bergonii, S. orientalis var. sennii, S. parviflora, S. vomeracea, Vermeulenia papilionacea var. aegaea.