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Aa (Orchidaceae) of Southern Central Andes: Taxonomy, Nomenclature, and a New Species with Dark Flowers



A new species, Aa tenebrosa, from the Yungas Montane Grasslands is described, illustrated, and compared to similar species. Descriptions, brief taxonomic notes, and data on the ecology of Aa species from the southern central Andes (Argentina) are provided.
Systematic Botany (2020), 45(4): pp. 760766
© Copyright 2020 by the American Society of Plant Taxonomists
DOI 10.1600/036364420X16033962925178
Date of publication December 8, 2020
Aa (Orchidaceae) of Southern Central Andes: Taxonomy, Nomenclature,
and a New Species with Dark Flowers
Claudia M. Mart´
Christian A. Zanotti,
and Gustavo J. Scrocchi
Centro de Investigaciones y Estudios de Diversidad Vegetal (CIEDIVE), Facultad de Ciencias Agrarias, Universidad
Nacional de Jujuy, Alberdi 47, 4600, Jujuy, Argentina
Instituto de Ecorregiones Andinas (INECOA-CONICET), Av. Bolivia 1239, 4600, Jujuy, Argentina
Instituto de Limnolog´
ıa Dr. Raul A. Ringuelet (CONICET), Bv. 120 y 62, 1900, La Plata, Buenos Aires, Argentina
Unidad Ejecutora Lillo (FML-CONICET), Miguel Lillo 251, 4000, San Miguel de Tucum ´an, Tucum´an, Argentina
Author for correspondence (
Communicating Editor: Liliana Katinas
AbstractA new species, Aa tenebrosa, from the Yungas Montane Grasslands is described, illustrated, and compared to similar species. De-
scriptions, brief taxonomic notes, and data on the ecology of Aa species from the Southern Central Andes (Argentina) are provided.
KeywordsChorology, morphological comparison, Yungas Montane Grasslands.
The genus Aa Rchb.f. (Orchidaceae: Cranichidinae) includes
about 25 Neotropical species distributed in the Andean region,
although Aa paleacea (Kunth) Rchb.f. reaches the mountains of
Costa Rica (Trujillo and Vargas 2011; Szlachetko and Nowak
2014). In South America, this genus is a component of different
kinds of vegetation, such as open scrub, woodlands, damp
mountain meadows, and paramo of the northern Andes above
2600 m a. s. l. (Wood 2003; Szlachetko and Nowak 2014); as
well as the dry Puna desert coast of Peru (Trujillo and Vargas
2011), and forest and montane grasslands of Yungas in the
central Andes above 1000 m a. s. l. (Cocucci 1954; Schinini et al.
2008; Mart´
ın and Scrocchi 2016).
This genus is characterized by its elongated peduncle, with
tubular and hyaline-diaphanous sheaths, generally greenish-
white (rarely black or orange) and non-resupinate flowers,
dorsal sepals and petals that are free from column, cucullate
lips with involute margin, and disc with a pair of subglobose
basal calli (Trujillo and Vargas 2011; Szlachetko and Nowak
2014). However, this genus has low morphological variation
and an unstable systematic status, since it has been transferred
to Altensteinia Kunth or Myrosmodes Rchb.f. and returned to Aa
several times by Reichenbach (1854, 1878), Schlechter (1912,
1920a, 1920b), and Schweinfurth (1958).
Recent molecular studies showed that some species of
Myrosmodes are nested in Aa (´
Alvarez-Molina and Cameron
2009), while the morphological and ecological evidence sup-
ports the separation of these genera in current taxonomic
studies. Thus, a new molecular phylogeny with a large tax-
onomic sampling is needed to delimit both these genera
(Trujillo and Vargas 2011).
In the Southern Central Andes (Argentina), the taxonomy of
Aa is controversial due to the lack of a comprehensive taxo-
nomic treatment. For example, for the Argentine flora (Correa
1996) and for the Cono Sur vascular flora (Schinini et al. 2008),
five species were recognized, but Mart´
ın et al. (2018) showed
that some specimens cited by these authors under Aa paludosa
Rchb.f. are clearly Myrosmodes gymnandra (Rchb.f.) C. A. Vargas
and M. paludosa (Rchb.f.) P. Ortiz. In addition, in these former
taxonomic works, Aa lorentzii Schltr. and Aa schickendanzii Schltr.
were recognized as synonyms of Aa hieronymi (Cogn.) Schltr.;
nevertheless, the diagnostic morphological characters (e.g.
number of lip lobes, presence of hairs on the scape, rachis, and
ovary) are incongruent among the type specimens of these taxa.
Therefore, we present a taxonomic revision of the genus Aa from
the Southern Central Andes including the description of a new
species; we proposed two new synonyms under Aa achalensis;
we designed a lectotype for Aa hieronymi, Aa lorentzii, Aa schick-
endantzii (5Aa achalensis); and we proposed a neotype for Aa
achalensis and Aa fiebrigii. In addition, a taxonomic key is included.
Materials and Methods
Taxa and CollectionsWe examined specimens from herbaria B, BAB,
CORD, G, GOET, JUA, LIL, LP, MCNS, and SI, and some digital images of
specimens from AMES, HBG, K, M, NY, W, and Z available at JSTOR
( or at the websites of the mentioned herbaria. The
herbarium acronyms follow Thiers (2020). All specimens examined were
compared with the type specimens, diagnoses, and original illustrations.
Morphological DescriptionsMorphological attributes were obtained
by direct observation using a stereoscopic microscope. The morphological
descriptions follow the terminology proposed by Font Quer (1953), Harris
and Harris (2001), Beentje (2010), and AOS (2020).
NomenclatureThe typification follows the International Code of
Nomenclature for algae, fungi, and plants (Shenzhen Code) (Turland et al.
2018). Details about the selected type materials are included as taxonomic
notes under the species.
A total of five Aa species were recognized from Southern
Central Andean species: Aa achalensis (5Aa lorentzii and Aa
schickendanzii), Aa fiebrigii,Aa hieronymi,Aa weddelliana, and Aa
tenebrosa, a new species herein described from Montane
Grasslands in Argentina.
Key to the Species
1. Leaves linear, less than 5 mm wide; flowers black and brown-greenish . .....................................................Aa tenebrosa
1. Leaves ovate-lanceolate, greater than 10 mm wide; flowers white with green tints . . . . . . . ...............................................2
2. Scape, rachis, and ovary glabrous ..................................................................................Aa achalensis
2. Scape, rachis, and ovary pilose . .............................................................................................3
3. Lip 5-sublobed; pilose and hairy-glandular ovary ..................................................................Aa hieronymi
3. Lip 3-lobed; pilose ovary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Leaves shorter than the length of the scape, narrowly lanceolate . . . ................................................Aa fiebrigii
4. Leaves one to two times longer than the scape, ovate . . . ......................................................Aa weddelliana
Taxonomic Treatment
AA ACHALENSIS Schltr., Repert. Spec. Nov. Regni Veg. 16: 358.
1920. [31 Apr 1920]. TYPE:ARGENTINA.[C´ordoba]: Sierra
Achala de C´ordoba, am fube des Cerro Champaqui,
oberhalbdes Rio de Latre,29 January 1877, G.H.E.W.
Hieronymus 796 [neotype: CORD00002203! designated
here; isoneotype: GOET008353!].
Aa lorentzii Schltr., Repert. Spec. Nov. Regni Veg. 16: 438. 1920.
[15 Jul 1920]. TYPE:ARGENTINA. [Tucum´an]: Sierra de
Tucum´an prope La Cienega, [1014 January 1874], P.G.
Lorentz et G.H.E.W. Hieronymus 617 (lectotype: GOET008356!
designated here; isolectotypes: CORD00002204!,
NY00008551!, SI000165!, SI092353!). Syn. nov.
Aa schickendanzii Schltr. [as Aa schickendantziiby Correa 1996
and Schinini et al. 2008], Repert. Spec. Nov. Regni Veg. 16:
438. 1920. [15 Jul 1920]. TYPE:ARGENTINA. [Catamarca]:
Alto de la Toma, Granadillas, November 1873,
F. Schickendanz 264 (lectotype: CORD00002205! designated
here; isolectotypes: GOET008355!, SI092352!). Syn. nov.
Plants terrestrial. Roots fleshy, fasciculate, pubescent.
Leaves basal, ovatelanceolate, sub-erect, 6930.61.2 cm.
Inflorescence slender, erect, up to 32 cm long, glabrous,
enclosed by broad, hyaline and diaphanous sheaths, termi-
nated in a densely many flowered cylindrical spike of 57cm
long, rachis of the spike glabrous. Floral bracts deltoid to
lanceolate, acute to obtuse, margin entire to slightly erose,
concave, 4534 mm, reflexed, somewhat surpassing the
flowers. Flowers white, glabrous. Dorsal sepal ovate to lan-
ceolate, obtuse, 1-nerved, reflexed, 1.72.0 31.31.5 mm.
Lateral sepals shortly connate at the base, obliquely oblong-
lanceolate, acute or slightly obtuse, entire, somewhat carinate,
1-nerved, 22.5 311.5 mm. Petals obliquely oblong-
lanceolate, obtuse, 1-nerved, up to 22.3 30.81.1 mm. Lip
cucullate, globose to ellipsoid, fleshy (except the margins),
notably 3-lobed, margins involute, with moniliform hairs,
2.02.7 32.55 mm. Column short, emarginate, glabrous.
Ovary sessile, ellipsoid, glabrous, 23 mm long.
Distribution and HabitatAa achalensis grows in Argentina
(Catamarca, C´ordoba, Jujuy, La Rioja, San Juan, and Tucum ´an
Provinces) at 15003500 m a. s. l., in the grasslands of the Chaco
Serrano and Yungas montane forest (Sobral and Fracchia 2010).
This species was placed into the Vulnerable category at the
global level in the IUCN Red List Criteria (Vischi et al. 2004), but
the new taxonomic circumscription of Aa achalensis suggests that
this status should be re-evaluated.Flowering and fruiting plants
have been recorded from October to April.
Taxonomic NotesThis species differs from all other
Argentinian Aa species by its glabrous reproductive and
vegetative structures. In the protologue of Aa achalensis
Schlechter (1920a: 358) cited Argentina: Sierra Achala de
ordoba, am Fuße des Cerro Champaqui, oberhalb des Rio de
Latre G. Hieronymus no. 796, am 27. Febr. 1877.This type
specimen was housed in B, but it was destroyed in the Second
World War (Dr. R. Vogt pers. comm.). We found two duplicates
from Hieronymus´s collections housed in GOET and CORD
whose labels have the same collection number and locality, but
they differ on the date mentioned in the protologue, 27 Feb 1877
(vs. 29 Jan 1877). A neotype for the name Aa achalensis is necessary
(cf. Art. 9.139.16, Turland et al. 2018). Therefore, we choose the
sheet CORD00002203 as neotype.
Schlechter (1920b: 439) cited in the protologue of Aa
schickendanzii Argentina: Alto de la Toma, Granadillas-
F. Schickendanz no. 264, Nov. 1873.We found three dupli-
cates from Schickendanz´s collections deposited in GOET,
CORD, and SI. We choose the sheet CORD00002205! as a
lectotype because it has the original label with Schickendanz´s
handwriting, and for being the most complete specimen.
In the protologue of Aa lorentzii, Schlechter (1920b: 438) cit ed
Argentina: Cienega. P. G. Lorentz and G. Hieronymus
no.617,Jan.1874.Four of Lorentz´s collections duplicates
were found in different herbaria: CORD, GOET, NY, and SI.
We choose the specimen GOET008356! as a lectotype, be-
cause it bears the original label and it is the most complete
Aa schickendanzii and Aa lorentzii were considered synonyms
of Aa hieronymi by Williams (1939), Hoehne (1940), Correa
(1996), and Schinini et al. (2008). After a detailed morpho-
logical study of specimens from both general collection and
type specimens, we found that the scape, rachis, and ovary is
glabrous in Aa schickendanzii and Aa lorentzii (vs. glandular-
pubescent in Aa hieronymi); the lip is 3-lobed (vs. 5-sublobed
lip); and the margin of the lip has moniliform hairs (vs. fim-
briate), corresponding to the characters described for Aa
achalensis. Therefore, we propose Aa schickendanzii and Aa
lorentzii as synonyms of Aa achalensis.
Representative Specimens ExaminedArgentina.CATAMARCA:
Cuesta de El Totoral, 1000 m, 04-X-1957. F. Vervoorst 3400 (LIL). Andalgal ´a,
El Candado, 24-X-1915. P. J¨orgensen 1244 (LIL). CORDOBA: Calamuchita,
Cerca de la cumbre del Cerro Champaqu´
ı, 2800 m, 15-I-1952. A.T. Hunziker
9643 (CORD). Falda E del Cerro Champaqu´
ı, 26002700 m, 15-I-1952. A.T.
Hunziker 9643 (CORD). Cumbre de uno de los picos del Cerro Champaqu´
17-XII-1885. F. Kurtz 3056 (CORD). Pocho, Ruta 20 (Km 788), Arroyo Aguas
Turbias, 24-XI-1983. R. Subils et al. 3235 (CORD). Punilla, Sierra Grande
(falda E), Ruta 20, Cerro Blanco, al oeste de El Durazno, 22-X-1983. Subils
et al. s.n. (CORD16099). Quebrada del Condorito, en el sendero hacia la
Quebrada, 31°370340S 64°420220O, 14-XI-2011. A. Romanutti 225 (CORD).
ıo Cuarto, Punta sur de la Sierra de Comechingones, en Alpa Corral a
orillas del Arroyo Las Moras, ca. 800850 m, 31-X-1982. A.T. Hunziker
et al.24411 (CORD). Valle de Punilla, Cerro Uritorco, Capilla del Monte,
12-XI-1917. C.C. Hosseus 880 (CORD). JUJUY: Volc´an, lagunas occi-
dentales, 11-I-1927, sin colector s.n. (LIL 51934). Tumbaya, Abra de Tiraxi,
cumbre, 3200 m, 31-X-1952. H. Sleumer 3154 (LIL). La RIOJA: Castro
Barros, Anillaco, Quebrada del Por tezue lo , 1796 msnm , 28 -IV-2 01 0.
A. Sobral. s.n. (CORD14001). Cumbres de Velazco- Sanagasta, 2000 m, 2-
XI-1980. J.A. Gonz´alez 231 (LIL). SAN LUIS:Jun
ın, Sierra de Comen-
chingones, inmediaciones de las cumbres frente a El Rinc ´on, 9-II-1956, A.T.
Hunziker 11817 (CORD). TUCUM ´
ıdel Valle, campus T ¨urpe, 1990 m,
5-XI- 1978. A.M. T¨urpe 3059 (LIL).Valle de Taf´
ı, 2000 m. 24-XII-1924.
R. Schreiter s.n. (LIL 51935). Taf´
ı, 2-XI-1918. R. Schreiter s.n. (LIL 52136).
ıdel Valle. 15-IX-1941. R. Schreiter s.n. (LIL 93559). Taf´
noa (San
Jos´e), 2800 m, XII-1931. R. Schreiter 6993 (LIL). Taf´
ıo Blanco. 22-XII-1907.
M. Lillo 9398 (LIL). Valle de Taf´
ı, 2000 m, 21-XI-1927. R. Schreiter 5767 (LIL).
ıdel Valle, Quebrada de la Bolsa, 3000m, 25-I-1950. H. Sleumer 260 (LIL).
ıdel Valle, 2000 m, 20-XI-1949. J. Araque & F. A. Barkley 19Ar226 (LIL). La
Ci´enaga, 2600 m, 22-XII-1908. M. Lillo 8821 (LIL).
AA FIEBRIGII (Schltr.) Schltr. Repert. Spec. Nov. Regni Veg. 11:
150. 1912. [20 Jul 1912]. Altensteinia fiebrigii Schltr. Repert.
Spec. Nov. Regni Veg.10: 445. 1912. TYPE:BOLIVIA. [Tarija]:
Bei Calderillo, 3200 m.a.s.l., March 1904, K. Fiebrig 3557
(neotype: G00168571! designated here; isoneotypes:
B100002790!, HBG500272!, M0066903!, Z000050848!).
Plants terrestrial and/or epiphytic. Roots fleshy, fasciculate.
Leaves basal, lanceolate, acute, 820 313 cm. Inflorescence
erect, up 25 cm long, pubescent, enclosed by diaphanous
sheaths, terminated in a densely many-flowered cylindrical
spike 56 cm long, rachis of the spike densely pilose. Floral
bracts ovate, rounded to acute, margins slightly erose, dorsally
hairy, 3.5 35 mm, reflexed, somewhat surpassing the flowers.
Flowers white or slightly greenish. Dorsal sepal oblong to
ovate, acute, entire, dorsally hairy at the base, recurved,
1.82.5 311.3 mm. Lateral sepals obliquely oblong-
lanceolate, rounded, somewhat carinate to erose, glabrous,
34311.5 mm. Petals obliquely linear-lanceolate, rounded to
acute, entire to somewhat sub-dentate, reflexed, 1.82.7 3
0.71 mm. Lip cucullate, globose, fleshy (especially in the
center), 3-lobed, with margins involute, lacerate to fimbriate,
3.7 35 mm. Column short, sessile, glabrous. Ovary sessile,
subcylindric, pilose, 1.53 mm long.
Distribution and HabitatAa fiebrigii occurs in Bolivia
(Tarija Department) and Argentina (Jujuy and Tucum´an Prov-
inces) at 17002700 m a. s. l., in humid montane grassland and
forest of Yungas. This species has also been found growing as an
epiphyte on Polylepis spp. (Rosaceae) and Sambucus nigra var.
peruviana (Adoxaceae). Flowering plants have been recorded from
December to March, and fruiting has been recorded in March.
Taxonomic NotesAa fiebrigii is similar to Aa weddelliana;the
taxa differ in that the leaves shorter than the length of the scape,
narrowly lanceolate (vs. leaves one to two times longer than the
scape, ovate in A. weddelliana), rachis densely pilose(vs. sparsely
pilose), and floral bracts irregularly dentate (vs. erose).
In the protologue of Altensteinia fiebrigii, Schlechter (1912:
445) cited Bolivia: Bei Calderillo, c. 3200 m ¨u. D. M.- K. Fiebrig
no. 2920, bl ¨uhend im M ¨arz 1904,but did not specify an
herbarium where the type specimen was deposited. The type
specimen of A. fiebrigii deposited in B was destroyed in the
Second World War (Dr. R. Vogt pers. comm.). We found some
specimens corresponding to A. fiebrigii (collected by Fiebrig) in
AMES, B, HBG, M, and Z, whose labels have the same locality
and date (cited by Schlechter 1912) but a different collection
number (3557 instead of 2920). A neotype for the name
A. fiebrigii is necessary (cf. Art. 9.139.16, Turland et al. 2018).
Therefore, we choose the sheet G00168571! as neotype because
it is a complete specimen.
Representative Specimens ExaminedArgentina. JUJUY: Dr. Manuel
Belgrano, entre Le´on y Nevado de Cha~
ni, Abra Delgada, 10-III-1963. H.A.
Fabris 4171(CORD). TUCUMAN:Chicligasta, Est.Las Pavas, Pte. LaCascada,
2600 m, 11-V-1924. S. Venturi 3018 (LIL). (Alpachiri) El Bolon a la Cascada,
26-III-1953. T. Meyer 17718 (LIL). Orilla de Laguna del Tesoro, 08-I-1965.
Legname & Cuezzo 5483c (LIL). Est. Las Pavas, 2700 m, 02-I-1927. S. Venturi
4823 (LIL). La Cascada (Est. Chipt.), 2600 m, 11-III-1924. S. Venturi 30187
(LIL). Taf´
ı, Corral de los tape~
nos, Carpinchango, 10-X-1907. M. Lillo 9400
(LIL). Quebrada de los Alisos, Casa de Piedra, 19-X-1907. M. Lillo 9399 (LIL).
Quebrada Carpinchango, 1700 m, 23-I-1908. M. Lillo 7352 (LIL).
AA HIERONYMI (Cogn.) emend. Schltr., Repert. Spec. Nov. Regni
Veg. 16: 437. 1920 [31 Jul 1920]. Altensteinia hieronymi
Cogn., Fl. Bras. 3: 3: 245. 1895. TYPE:ARGENTINA. Salta: ad
Cuesta inter Yacone et Los Potreros, [17 March 1873],
P.G. Lorentz et G.H.E.W. Hieronymus 336 (first step of
lectotypification designated by R. Schechter, Repert.
Spec. Nov. Regni. Veg. 16: 438, second step of lectoty-
pification: GOET008354! designated here; isolectotype:
Plants terrestrial. Roots fleshy, fasciculate, pubescent.
Leaves basal, ovate-lanceolate, 420 30.82 cm. Inflorescence
slender, erect, up to 31 cm long, pubescent (hairs white, 1.2 mm
long), enclosed by hyaline and diaphanous sheaths (margin
fimbriate and pilose in the centre), terminated in a densely
many flowered cylindrical spike 313 cm long, rachis of the
spike pubescent. Floral bracts ovate, acute to obtuse, margins
entire or slightly erose, reflexed, 9.5 36.2 mm. Flowers white,
greenish at the base. Dorsal sepal oblong to ovate, slightly
acute, margin entire, 1-nerved, 1.6 31.1 mm. Lateral sepals
obliquely oblong-lanceolate, obtuse, sparingly glandulous
pubescent, 1-nerved, 2.8 31.2 mm. Petals obliquely ovate-
lanceolate, obtuse, margin entire, 1-nerved, 2.2 30.6 mm.
Lip cucullate, globose, slightly 5-sublobed (the three central
lobes smaller than the lateral lobes), margins involute, fimbriate,
2.02.5 33.75 mm. Column short, emarginate. Ovary sessile,
globose to subcylindrical, glandulous pubescent, 3.2 34.2 mm.
Distribution and HabitatAa hieronymi occurs in northern
Argentina (Jujuy and Salta) at 30003500 m a. s. l., growing
in forests and montane grasslands of the Yungas. Flower-
ing and fruiting plants have been recorded from January to
Taxonomic NotesAa hieronymi is easily distinguished
from other Aa species by its densely pilose rachis, 5-sublobed lip,
and glandulous pubescent ovary. When Cogniaux (1895: 245)
described Altensteinia hieronymi, he cited seven collections [Lorentz
et Hieronymus 336;Lorentz et Hieronymus 617;F. Schickendantz 264;
Hieronymus s.n.; Hieronymus sine no. et n. 796;Schnyder 598].
However, Altensteinia hieronymi was transferred to the genus Aa
(Schlechter 1912). Later, Schlechter (1920a, b) describe a new
species based on some type materials cited by Cogniaux: Aa
lorentzii (Lorentz & Hieronymus 617), Aa schickendanzii (F.
Schickendantz 264), and Aa achalensis (Hieronymus 796). Sub-
sequently, Schlechter (1920b: 438) designated a type specimen
(Lorentz et Hieronymus 336) and emended the morphological
description of Aa hieronymi.Weconsiderthisactionasafirststep
of lectotypification according to Art. 9.17 of the ICN (Turland
et al. 2018), but this author did not specify the herbarium where
correspond to Lorentz et Hieronymus 336 (GOET and CORD). For
this reason, we designate the sheet GOET008354! as a second step
of lectotypification.
Representative Specimens ExaminedArgentina. JUJUY:Tum-
baya, Abra Grande de Volc´an, cumbres 3200 m, 23-I-1953. H. Sleumer
3510 (LIL). SALTA:SantaVictoria,ArroyoPe
na Negra, 22°150060S
65°040390W, 3360 m, 15-II-2009. F. O. Zuloaga, et al. 10762 (SI).
Aa tenebrosa C.M.Mart´
ın & G.J.Scrocchi sp. nov. TYPE:
ARGENTINA. Salta: Dep. Santa Victoria, Ruta Provincial 7,
de Santa Victoria a Lizoite, 22°160180S, 65°050250W,
3730 m, 15 February 2009, Zuloaga et al. 10773 (holotype:
SI092427!; isotypes: CORD!, CTES0043314!).
Plants small, terrestrial. Roots fleshy, fasciculate, pu-
bescent. Leaves basal, linear-lanceolate, acute to acumi-
nate, coriaceous, 813 30.30.5 cm. Inflorescence erect,
1017 cm long, pubescent, enclosed by hyaline and di-
aphanous sheaths, terminated in a short spike, formed by
few flowers, 13 cm long, rachis pubescent. Floral bracts
ovate to subulate, acute, margins slightly erose at the apex,
4532.52.9 mm, reflexed, surpassing the flowers, brown
with whitish edges. Black and brown-greenish flowers.
Dorsal sepal ovate, acute, erose at the apex, glabrous,
1.5 31.1 mm. Lateral sepal oblong, obtuse, entire, gla-
brous, 2 30.8 mm. Petals ovate-lanceolate, acute, margin slightly
erose, 1.8 31 mm. Lip cucullate, with a narrow opening, margins
involute, deeply laciniate, 2.7 31.5 mm (natural position).
Column short, emarginated, glabrous. Ovary s es sil e, glo bo se,
pubescent, 1.52 mm long. Figures 1, 2.
Distribution and HabitatAa tenebrosa is only known from
the type locality, Serran´
ıa de Santa Victoria (Salta, Argentina).
This species grows on hillsides, between 35003730 m a. s. l., in
Yungas Montane Grasslands associated with rocky outcrops.
This region has high diversity, and is biogeographically im-
portant due to its high number of endemic species (Mart´
ın et al.
2017; Mart´
ın 2019).
Aa tenebrosa shares its habitat with species such as
Mandevilla pentlandiana (A.DC.) Woodson; Philibertia
lysimachioides (Wedd.) T.Mey. (Apocynaceae); Chuquiraga
longiflora (Griseb.) Hieron., Hieracium argentinense Zahn,
H. neofurcatum Sleumer, Lucilia recurva Wedd., Onoseris
hastata Wedd., Senecio crepidifolius DC. (Asteraceae);
Gaultheria erecta Vent., Gaylussacia cardenasii A.C.Sm.
(Ericaceae); Brachyotum microdon (Naudin) Triana (Mel-
astomataceae); Cyclopogon oliganthus (Hoehne) Hoehne &
Fig. 1. Aa tenebrosa. A. Type. B. Plant. C. Inflorescence.
Fig. 2. Aa tenebrosa. A. Plant. B. Inflorescence. C. Flower, frontal view. D. Flower, dorsal view. E. Flower, lateral view. F. Lip and ovary, lateral view.
GG. Lateral sepals. HH. Dorsal sepal. II. Petals. J. Gynostemium. Drawn from Zuloaga et al. 10773 (SI).
Schltr. and Odontorrynchus castillonii Hauman (Orchid-
aceae); Agalinis fiebrigii (Diels) Darcy (Orobranchaceae); Briza
uniolae (Nees) Nees ex Steud., Cortaderia hieronymi (Kuntze)
N.P.Baker et H.P.Linder, Danthonia secundiflora J.Presl., Elymus
scabriglumis (Hack.) A.L¨ove, and Jarava ichu Ruiz et Pav. var
ichu (Poaceae); Thalictrum venturii Boivin (Ranunculaceae);
Nierembergia rivularis Miers (Solanaceae); Barbaceniopsis boli-
viensis (Baker) L.B.Sm. (Velloziaceae); Viola micranthella Wedd.
and V. rodriguezii W.Becker (Violaceae); among others (pers.
obs.). Flowering plants have been recorded in February.
EtymologyFrom the Latin tenebra (darkness, shadow,
obscurity) in reference to the colour of the flowers.
ObservationsAa tenebrosa is recognized as a new species
based on a combination of morphological features that dis-
tinguish it from another species with dark flowers, A. leucantha
(Rchb.f.) Schltr, endemic of the northern Andes (Colombia,
Venezuela, and Ecuador) (see Szlachetko and Nowak 2014;
Nowak 2019). The new species is distinguished by the floral
segments up to 2 mm (vs. above 3 mm in A. leucantha), pu-
bescent rachis (vs. glabrous in A. leucantha), and pilose ovary
(vs. obscurely pilose at the base of lateral sepals in
A. leucantha). Finally, Aa tenebrosa grows in Yungas Montane
Grasslands (Southern Central Andes), and A. leucantha grows
in paramo (Northern Andes).
AA WEDDELLIANA (Rchb. f.) Schltr. Repert. Spec. Nov. Regni
Veg. 11: 150. 1912. Altensteinia weddelliana Rchb. f. Xenia
Orchid. 3: 19. 1878. TYPE:BOLIVIA.Viciniis Soratae. Par-
acollo in schistosis. Region subalpine 3400 Met. Decembri
1856 Januario 1857G. Mandon 1167 (holotype: W;
isotype: G00168572!, G00168573!, K).
Plants terrestrial, sometimes epiphytic. Roots fleshy, fas-
to acuminate, 914 31.52cm.Inflorescenceslender,erect,
up 38 cm long, enclosed by hyaline and diaphanous
sheaths, terminated in a cylindrical spike, formed by nu-
merous flowers, 2.67.5(11) cm long, rachis sparsely
hairy. Floral bracts ovate, acute, margins slightly erose,
4532.53.5 mm, surpassing the flowers. Flowers white,
light brown at the base. Dorsal sepal oblong to ovate,
acute, dorsally hairy, 1.5230.81.2 mm. Lateral sepals
obliquely linear-lanceolate, obtuse, dorsally hairy at the
base, somewhat erose at the apex, 1-nerved, 22.5 3
0.81.2 mm. Petals obliquely linear-lanceolate, acute, 1-
nerved, margin slightly erose, 1.82.3 30.51.1 mm. Lip
cucullate, transversely elliptic, fleshy (except the margins),
3-lobed, margins involute, lacerate, 2.5 33.5 mm. Column
short, glabrous. Ovary sessile, globose to subcylindric,
pubescent, 1.82.2 mm long.
Distribution and HabitatAa weddelliana grows in
Argentina (Jujuy, Salta, Tucum´an, and Catamarca provinces),
Bolivia (Cochabamba and La Paz departments), and Peru
(Arequipa, Ica, and Lima departments). In Argentina, it grows
in forest and montane grassland of the Yungas, sometimes as
epiphytic on Polylepis australis Bitter (Rosaceae) and Podocarpus
parlatorei Pilg. (Podocarpaceae) at 13003500 m a. s. l. In
Bolivia, it grows at 30004500 m a. s. l., in dry valleys, and wet
and dry Puna (Ibisch 2014). In Peru, it was found at
3003800 m a. s. l., in sandy, sandy-clay, stony and rocky soils
of Lomas formations from desert coast, as well as in paramo
and puna (Trujillo and Delgado Rodriguez 2011). Flowering
and fruiting plants have been recorded from September to
Taxonomic NotesAa weddelliana is similar to A. fiebrigii,
the differences between these two taxa are mentioned in the
taxonomic notes of Aa fiebrigii.
Representative Specimens ExaminedArgentina. CATAMARCA:
Andalgal´a, Los Que~
noales, arriba de la Mesada de las Rosas, 2600 m, 15-I-
1952. H. Sleumer 2243 (LIL). Cumbres de suncho, Quebraditas del Porte-
zuelo, Sta. Ana. ca. 2150 m, 08-II-1952. H. Sleumer 2293 (LIL). JUJUY:
Estaci´on Volc´an, Mula Muerta, 2700 m, 15-I-1927. Castillon 151 (LIL).
Volc´an, loma del tambo, 2500 m, 22-I-1924. R. Schreiter 4639 (LIL). Tilcara,
Est. Vieja, cerca de Abra Mayo, 3300 m, 21-III-1952. Petersen & Hyerting 49
(LIL). SALTA: La Caldera, Potrero del Castillo, 2500 m, 14-III-1952.
H. Sleumer & F. Vervoorst 2805 (LIL). Subida al Nevado del Castillo por
Malpaso, 3400 m, 15-III-1952. H. Sleumer & F. Vervoorst 2927 (LIL).
TUCUMAN: Chicligasta, Est. Las Pavas, Pte. del Bayo, entre los pastos,
3200m, 11-III-1924. S. Venturi 3050 (LIL). La Cascada, 2600 m, 23-III-1953.
T. Meyer 20206 (LIL). Estancia Santa Rosa, 3600 m, 06-I-1927. S. Venturi 4782
(LIL). Entre La Cascada y Las Cuevas, 3000 m, 10-X-1949. T. Meyer 15055
(LIL). Taf´
ı, Cumbre de Anfama, 2700 m, 23-III-1922. R. Schreiter s.n.
(LIL52127). Cumbre de Anfama, 2500 m, 09-III-1919. R. Schreiter 811 (LIL).
Cuesta de Malamala, 2700 m, 02-IV-1904. M. Lillo 3423 (LIL). Cuesta de
Malamala, 2700 m, 7-III- 1905. M. Lillo 4358 (LIL). Trancas, Pampa Grande,
2000 m, I-1896. M. Lillo 2111 (LIL).
We want to thank Francisco Rojas for the illustrations, Dr Robert Vogt
(B) and the curators of BAB, CORD, JUA, LIL and SI for providing access to
herbarium collections. We are grateful to two anonymous reviewers for
useful comments on this work.We also thank Instituto Darwinion for the
photographs and Consejo Nacional de Investigaciones Cient´
ıficas y
ecnicas, Argentina (CONICET) for provided financial support. CMM and
CAZ thanks Fondo Nacional para la Investigaci ´on Cient´
ıfica y Tecnol ´ogica
(FONCyT) for financing the research stipulated in the project PICT 2016
Author Contributions
All authors conceived the study, and gathered the data in the herbaria,
and CMM also in the field. CMM and CAZ conducted the analyses. CMM,
CAZ, and GJS wrote the manuscript.
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