Iridaceae : Tigridieae ) , a new species from South Peru

Tigridia arequipensis (Iridaceae: Tigridieae) is a new species found in the province of Arequipa (department of Arequipa), South Peru. It is unique by its white to pale white (or pale lilac) flowers, outer tepals with purplish maroon and dark yellow spots and stripes, and inner tepals with pale purplish and bluish spots and stripes. Tigridia arequipensis is morphologically similar to T. raimondii and T. philippiana, it differs by having longer basal leaves, narrower and larger bracts, and outer tepals ovate and longer fruits.


RESEARCH ARTICLE
InTRoduCTIon Tigridia Juss.(Iridaceae: Tigridieae) is a New World genus of about 50 species (Rodriguez & Ortiz-Catedral 2003).In Peru there are 11 known species (Macbride 1936, Brako & Zarucchi 1993, Goldblatt 1998, Tropicos 2014).Six species are endemic to this country and the knowledge of their distribution is still incomplete (León 2006).The discontinuous geographic distribution in North and South America offers an ideal model to explore biogeographical aspects (Rodríguez & Ortiz-Catedral 2003).The variation in colour, size and form of the perianth in Tigridia indicate that the adaptation of the pollinators has been an important factor for its diversification (Rodríguez & Ortiz-Catedral 2003).Presumably the species of Tigridia are hummingbird-pollinated (Rudall et al. 2003); they secrete copious amounts of sugary nectar from nectaries on the inner tepal claws (Cruden 1971).Celis (2012) studied the phylogenetic relations of the tribe Tigridieae suggesting new combinations in Tigridia and Mastigostyla based on plastid (cpDNA) and nuclear (nDNA) genomes.
During February and March of 2011 and 2012, we collected a tall Tigridia on the xeric scrublands of the province of Arequipa (department of Arequipa), South Peru.After a detailed morphological analysis, we conclude that this is an undescribed species.Montesinos, Pauca & I.Revilla, sp.nov.-Fig. 1 Subgenus.Tigridia.

Tigridia arequipensis
Etymology.Tigridia arequipensis is named after the province of Arequipa, where the species was found.
Ecology & Distribution -Tigridia arequipensis is distributed on clayey-sandy soils on rocky slopes, in the Arequipa Region   (Ravenna 1964, 1969, 1988, Brako & Zarucchi 1993, Goldblatt 1998, León 2006, Tropicos 2014).Conservation status -Following the criteria and categories of IUCN (2012), a preliminary status of Vulnerable (VU) is assigned (A1a+D1).The new species deserves protection because its total area of occupancy is less than 200 km 2 ; population size is estimated to be fewer than 200 individuals (D1); and we observed a reduction of the population mainly caused by human urbanization and habitat destruction (A1a).The suitable habitats for T. arequipensis on the xeric scrubland slopes in the Socabaya, Polobaya, Mollebaya and Quequeña districts are regarded as vulnerable because changes in annual rainfall, volcanic activity, exploitation of natural resources and uncontrolled urbanization, may all potentially reduce their extent.
Note -The new species is morphological similar to Tigridia raimondii Ravenna and T. philippiana I.M.Johnst.but is clearly distinguished by the white to pale white (or pale lilac) outer tepals with purplish maroon and dark yellow spots and stripes, and inner tepals with pale purplish and bluish spots and stripes.Moreover.it differs by having longer basal leaves and fruits, narrower and larger bracts and longer style branches.

dISCuSSIon
This species is known only from the xeric scrublands in the vicinity of the Arequipa city at elevations from 2490 to 3135 m.The flowering stem begins to grow with the onset of the rainy season, and anthesis occurs shortly thereafter.
Within Tigridia arequipensis two distinct morphological forms are recognizable.
In the vicinity of Quequeña and Alto Selva Alegre the colour of the corolla is pale lilac to pale white with a reticulum of purple spots and stripes on both blade and limb of the outer tepals.Near Yarabamba and Socabaya, the corolla have the colour of white to pale white, outer tepal purplish maroon with dark yellow spots and stripes.
Tigridia arequipensis is most similar to T. raimondii and T. philippiana in subg.Tigridia (Molseed 1970), but is a plant from high elevations, while T. raimondii and T. philippiana grow at lower elevations and in drier habitats.The white-flowered T. raimondii is a plant of subhumid lomas in Atiquipa, Arequipa at Table 1 Comparative data of some characters of Tigridia arequipensis and its closest relatives.

Fig. 2
Fig. 2 Map showing the distribution of Tigridia arequipensis and the other species occurring in Peru.
in South Peru.It grows terrestrial on superficial soils on rocky slopes and occasional humid environs in xerophytic-scrubland communities at an elevation of 2490-3135 m and in association with Ambrosia artemisioides Willd., Weberbauerocereus weberbaueri (K.Schum.exVaupel)Backeb., Solanum paposanum Phil., Anthericum eccremorrhizum Ruiz & Pav. and Mentzelia scabra subsp.chilensis(Gay)Weigend.Flowering and fruiting takes place between February and March, rarely in April.Fig.2shows the distributions of the Peruvian species Tigridia albicans