Aganisia Lindley (1839

Thiago E. C. Meneguzzo, José F. A. Baumgratz & Cássio Van Den Berg, 2015, Taxonomic studies in the Aganisia complex (Orchidaceae, Zygopetalinae), Phytotaxa 238 (1), pp. 1-39 : 4-5

1. Aganisia Lindley (1839 : misc. 45).

Aganisia sect. Typaganisia Kuntze in von Post & Kuntze (1903: 13), nom. illeg. Type:— Aganisia pulchella Lindley (1839 : misc. 45)

Acacallis Lindley (1853a: 1) . Aganisia sect. Acacallis (Lindl.) Kuntze in von Post & Kuntze (1903: 13). Type:— Acacallis cyanea Lindley (1853a: 1) .

Kochiophyton Schlechter ex Cogniaux in Cogniaux (1906b: 574). Type:— Kochiophyton negrense Schlechter ex Cogniaux in Cogniaux (1906b: 574).

Etymology:— Lindley did not explain the source of the name. It probably originates from Greek, γάνος, splendid, due to the author being delighted with the beauty of this plant, as cited in the protologue—“A very pretty new genus”—or an obscure nymph from Alpine mythology, Veneto, northeastern Italy, also known as Anguana.

Herbs epiphytic or hemiepiphytic, sympodial, rhizomatous, with thick, spongy roots. Flowering pseudobulbs inconspicuous, homoblastic, fusiform, orbicular in transverse section; cataphylls on pseudobulbs non-leafy, scarious, non-articulate. Leaves 1 per pseudobulb; petiole conduplicate, distinct from blade, margin non-hyaline; blade articulate, plicate, elliptic to narrow-elliptic, base cuneate, apex obtuse to acute, abaxial face with 5 more prominent nerves. Inflorescences racemose, axillary from an inner cataphyll, shorter than plant, rarely longer, erect, pedunculate, rachis lax, blooming acropetally; bracts lanceolate, adpressed; bracteole 1, lanceolate, shorter than the ovary. Flowers resupinate, pedicellate. Sepals with the dorsal one free, and laterals adnate to column feet and oblique, narrow-ovate or ovate. Petals free, narrowly elliptic, elliptic or orbiculate. Lip free, trilobed, unguiculate; lateral lobes highly reduced, deltoid or semi-elliptic; midlobe lateral lobes strongly reduced, margin entire; midlobe flabellate, elliptic or ovate, margin entire, undulate, minutely crenate or fimbriate; callus composed of an outer pair of lamellae with erose margins, fimbriate in distal part between lamellae, or apex with erose laminar margins, antrorse, or longitudinal laminae irregularly denticulate, the external pair higher than the inner one. Column semi-terete, foot shorter than the column, apex with oblong and conspicuous stigmatic wings; anther incumbent, clinandrium not projecting over the anther, margin entire, external face of anther cap bilobed, apex obtuse-denticulate or digitiform, inner face bilocular; pollinia 4, in 2 pairs, juxtaposed, oblong-ovoid, laterally compressed, unequal in size and shape, tegula oblong to elliptic, caudicle amorphous, viscidium transverse-oblong; stigma transverse; rostellum trilobed, midlobe narrowly triangular, lateral lobes reduced with concave margin, not exceeding the rostellum, rostellum remnant trilobed, midlobe acute and unequal to the lateral ones, lateral lobes truncate or trilobed, in the latter case the midlobe longer than the truncate and lateral ones. Capsules fusiform, 6-carinate, smooth surface; seeds not seen.

Distribution and habitat:— The genus occurs in northern and western South America, in the Amazon and Solimies Basins, Guiana and Guaporé Shields. It grows in the Amazon rainforests, in shady places close to water, from sea level to 200 m, rarely higher. Aganisia pulchella is also recorded for Trinidad and Suriname in riparian forest surrounded by savannahs and in a disjunct area in southern Bahia, eastern Brazil. In Brazil, the species grows in biome Amazônia and vegetation type floresta de igapó (black water seasonal floodplain forest), floresta de várzea (clear water seasonal floodplain forest) and campinarana (white sand forest); in biome Cerrado in mata de galeria (riparian forest); and biome Floresta Atlântica in restinga (sedimentary coastal shrub field and forest).

Aganisia pulchella has a disjunct distribution in northern South America and eastern Brazil. There is evidence that Floresta Atlântica and Amazônia once were a single biome connected in northeastern Brazil, which, due to increased aridity during the Pleistocene, became separated by Cerrado and Caatinga ( Bigarella et al. 1975, Mori et al. 1981). For the same species, occurrence in Trinidad could at first also sound like a disjunction because it is politically included in the Caribbean, but it is a continental island on the South American platform near the coast of Venezuela and not on the Caribbean platform like the rest of the Antilles ( Schultes 1960). Recent field observations in southern Bahia by one of us (TECM) suggest that its life form can be classified tentatively as a hemiepiphyte because most individuals grow on plant litter and later climb up the bases of tree trunks. TDWG code: 81 TRT-OO 82 FRG-OO GUY-OO SUR-OO VEN-OO 83 COL-OO PER-OO 84 BZC-MT BZE-BA BZE-MA BZN-AC BZN-AM BZN-PA BZN-RO BZN-RR.

Diagnostic characters:— The genus differs from the others in this study by its medium-sized plants (20 to 50 cm long), rhizomatous, inconspicous pseudobulbs covered by non-leafy, non-articulate and scarious cataphylls, articulate leaves with hyaline margins and plicate blades, inflorescences shorter than the leaves, rarely longer, lax rachis, big flowers (sepals up to 3.8 cm long), lateral sepals adnate to the column foot, lip with a hippocrepiform and ornamented callus and column with conspicuous stigmatic wings.

Generic delimitation:— The segregation of Acacallis from Aganisia was accepted without critical analysis by some authors ( Schlechter 1918a; Hoehne 1953; Senghas & Gerlach 1993c). Acacallis would include Acacallis cyanea and Acacallis frimbriata , and Aganisia only Aganisia pulchella . These authors referred to the lip of Aganisia as sessile. Schultes (1958) discussed this, and we agree with his views on the reliability of this character to distinguish these genera. We concluded that in fact the lip is unguiculate, and we also found that the column foot is shorter than column. Apart from that, we did not find any other diagnosable characters. Whitten et al. (2005) in a combined molecular analysis showed that Aganisia pulchella is sister to Acacallis cyanea and Acacallis fimbriata . Thus, we conclude there is no reason to separate these two genera.

Key to the species and forms of Aganisia

1 Lip with lateral lobes unconstricted, margin of midlobe entire........................................................................................ A. pulchella

- Lip with lateral lobes strongly constricted distally, midlobe margin undulate and inconspicuously crenate or fimbriate ................2

2 Lip with midlobe elliptic to ovate, strongly concave, margin fimbriate .......................................................................... A. fimbriata

- Lip with midlobe flabellate, slightly concave, margin undulate or inconspicuously crenate ............................................................3

3 Sepals, petals and lip white, rarely lip yellowish ..................................................................................................... A. cyanea f. alba

- Sepals, petals and lip lilac, rarely midlobe of lip yellowish................................................................................. A. cyanea f. cyanea