Ruellia simplex, an older and overlooked name for Ruellia tweediana and ruellia coerulea (Acanthaceae)
Cecilia Ezcurra1 & Thomas F. Daniel2
1Departamento de Botánica, Centro Regional Universitario Bariloche, Universidad Nacional del Comahue, Quintral
1250, 8400 San Carlos de Bariloche, Río Negro, Argentina; cezcurra@crub.uncoma.edu.ar (author for correspondence).
2Department of Botany, California Academy of Sciences, 875 Howard St., San Francisco, CA 94103, United States
of America.
Original recibido el 26 de febrero de 2007;
aceptado el 25 de julio de 2007
Abstract. Ruellia simplex, an older and overlooked name for Ruellia tweediana and Ruellia coerulea (Acanthaceae).
Ruellia simplex, the name of a species of Ruellia described from Cuba in 1870, is the oldest name
for the neotropical species generally known as Ruellia tweediana, Ruellia coerulea and Ruellia malacosperma.
Therefore Ruellia simplex has priority and reduces tha latter names to synonym. This species
has an amphitropical distribution in the New World, being found in southern United States, Mexico
and the Antilles, and in western Bolivia, southwestern Brazil, Paraguay, Uruguay, and northeastern
Argentina.
Keywords. Acanthaceae; Neotropics; Nomenclature; Ruellia.
Resumen. Ruellia simplex, un nombre más antiguo y hasta ahora ignorado para Ruellia tweediana y Ruellia coerulea (Acanthaceae).
Ruellia simplex, el nombre de una especie de Ruellia descripta para Cuba en 1870, es el nombre
más antiguo para una especie neotropical generalmente conocida como Ruellia tweediana, Ruellia
coerulea y Ruellia malacosperma. Por lo tanto Ruellia simplex tiene prioridad y reduce estos últimos
nombres a la sinonimia. Esta especie tiene una distribución anfitropical en el Nuevo Mundo, encontrándose
en el sur de Estados Unidos, México y las Antillas, y en el oeste de Bolivia, sudoeste de Brasil,
Paraguay, Uruguay, y noreste de Argentina.
Palabras clave. Acanthaceae; Neotrópico; Nomenclatura; Ruellia.
In his treatment of the Acanthaceae for Martius'
Flora Brasiliensis, Nees (1847a) described a new
species of Ruellia from Uruguay under the name
Arrhostoxylon microphyllum Nees. This plant of
humid habitats was characterized by its linear to
oblong-lanceolate, glabrous leaves, and axillary,
one- to few-flowered inflorescences. Later that
same year, in De Candolle's Prodromus, Nees
(1847b) described the same species under the different
name Cryphiacanthus angustifolius Nees
from material collected in Argentina (Entre Ríos)
and Mexico (Xalapa, Veracruz). Since then, the
nomenclature of this species has had an intricate
history. Two facts have made it so complex: 1)
both these names have earlier homonyms in Ruellia
and therefore cannot be used; 2) the plants
from North America and those from South America
have traditionally been treated as two different
species.
The disjunct distribution was overlooked by
authors that recently studied this species from
material collected in South America, e.g., Ezcurra
(1993a, b; 1999a), and Wasshausen & Wood
(2004). Nevertheless, a recent study of Ruellia in
Chiapas, Mexico (Daniel, 1995), does include
names used for North American material in the
synonymy.
Therefore this species, as originally proposed by Nees (1847b) and recently treated by Daniel
(1995), has a wide amphitropical distribution in
moist to wet, tropical and subtropical regions of
North and South America. Our studies of Acanthaceae
in North American, South American, and
European herbaria during the past two decades
reveal that the distribution of this species not only
includes southern North America (Mexico and
southern United States) and southern South America
(Bolivia, Paraguay, southern Brazil, Uruguay
and Argentina), but the Antilles, where the species
was described from Cuba under the name Ruellia
simplex Wright, and is also found in Dominican
Republic, Trinidad and Tobago, and Puerto Rico.
This is an older name that reduces to synonymy all
others recently used, such as Ruellia coerulea Morong
(Ezcurra, 1993a, b; 1999a, b; Daniel, 1995)
and Ruellia tweediana Griseb. (Wasshausen &
Wood, 2004). A complete synonymy of this species
is provided here.
Ruellia simplex Wright in Sauvalle, Flora Cubana: 97. 1870 ("1868"). An. Acad. Ciencias Med. Fis. Nat. La Habana 6: 321. 1870.TYPE: Cuba, Plantae Cubenses Wrightianae, en sabanas bajas y fangosas cerca del hato El Salado jurisdicción de San Cristóbal y Palacios, sine data, Wright 3642 (holotype NY!).
Arrhostoxylon microphyllum Nees in Mart., Fl. Bras. 9:
61. 1847. Ruellia microphylla (Nees) Lindau, Engl.
Bot. Jahrb. 19 (Beibl.) 48: 16. 1894, non Cav. 1801.
Ruellia ignorantiae Herter, nom. nov., Rev. Sudamer.
Bot. 4: 193. 1937. Syn. nov. TYPE: Uruguay, Montevideo
ad S. Luciam sub fruticibus ripas fluviorum
obumbrantibus, sine data, Sellow s.n. (holotype B
destr.; isotypes not found).
Cryphiacanthus angustifolius Nees in DC., Prodr. 11:
199. 1847, non Ruellia angustifolia Sw., 1788. Ruellia
tweediana Griseb., nom. nov., Symb. Fl. Argent.:
259. 1879. Ruellia spectabilis Britton, nom. nov.,
Ann. New York Acad. Sc. 7: 192. 1893, non Nicholson,
1886. Ruellia brittoniana Leonard, nom. nov., J.
Wash. Acad. Sci. 31: 96. 1941. Syn. nov. TYPE:
Argentina, Entre Rios, sine data, Tweedie s.n. (lectotype,
K! designated by Grisebach, 1879).
Ruellia coerulea Morong in Morong et Britton, Ann.
New York Acad. Sc. 7: 193. 1893. Syn. nov. TYPE:
Paraguay, falls of Pilcomayo River, 1888-1890,
Morong 1013 (holotype NY!, isotypes MO!, US!).
Ruellia malacosperma Greenm., Proc. Amer. Acad. Arts
34: 572. 1899. Syn. nov. TYPE: México, San Luis
Potosí, Tampico, 30-V-1898, Pringle 6806 (lectotype
GH! selected by Daniel 2005, isolectotypes K!, US!,
MO photograph!).
Ruellia longipes Urb., Symb. Antill. 9: 129. 1923. Syn.
nov. TYPE: Cuba, Camaguey 'in pascuis salsuginosis
prope Camaguey ad septentrionem versus', 11-
V-1917, Ekman 8601 (holotype HAC n.v., isotype
S!).
Descriptions. Dawson (1979), Ezcurra (1993a, b; 1999b), Daniel (1995, 2004), Wasshausen (2003).
Illustrations. Fernald (1945: pl. 840), Dawson (1979), Ezcurra (1993a, b; 1999b).
Distribution. Southern United States, Mexico, the
Antilles (Cuba, Dominican Republic, Puerto Rico,
and Trinidad and Tobago), western Bolivia, southwestern
Brazil, Paraguay, Uruguay, and northeastern
Argentina. It grows in sunny areas on periodically
inundated soils, such as margins of pools, or
along ditches and watercourses.
The amphitropical distribution of this species is
not a rare characteristic in the Acanthaceae. Other
species of Ruellia [(e.g., Ruellia erythropus (Nees)
Lindau] and Justicia [e.g., Justicia ramulosa (Morong)
C. Ezcurra)] have similar distributions,
being present in southern Mexico and/or Central
America, and northern Argentina, Paraguay, southern
Bolivia and southwestern Brazil (Ezcurra,
1993b, 2002; Daniel, 2005). Several other species
of Acanthaceae of southern South America have
clear affinities with North American species and
their distribution and relationships, probably as
result of long distance dispersal events during the
evolutionary history of the groups, should be
investigated.
Acanthaceae seeds frequently become mucilaginous
when wet (e.g., in Ruellia), or have surface
ornamentations such as prickles, hairs or spines
(e.g., in Justicia) that make them adhesive and therefore
adapted to dispersal by animals by ectozoochory.
In this way, migratory birds could have
aided long-distance dispersal of species that presently
have disjunct distributions between North
and South America. Humans have also aided the
dispersal of several Acanthaceae species cultivated
as ornamentals. Once introduced into a new area,
many Acanthaceae become naturalized in humandisturbed
habitats, as has been observed in 18 species
of ornamental Acanthaceae from tropical
America that have been reported to have escaped
cultivation and naturalized in Indo-Pacific Islands
(Meyer & Lavergne, 2004).
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