Euphorbia paniculata subsp . calcicola U . Schwarzer & Vicens subsp . nov . ( Euphorbiaceae ) , a new taxon of the southwestern Portugal

Abstract. A new subspecies of E. paniculata Desf., E. paniculata subsp. calcicola U.Schwarzer & Vicens subsp. nov., is described. It grows in the proximity of the town of Sagres —southwestern Portugal— on calcareous substrate. Resumen. Se describe una nueva subspecie de E. paniculata Desf., E. paniculata subsp. calcicola U.Schwarzer & Vicens subsp. nov. Crece en la proximidad de la ciudad de Sagres —suroeste de Portugal— en sustrato calcáreo.


INTRODUCTION
The genus Euphorbia L., in strict sense, is represented in the Iberian Peninsula by 54 species (Benedí & al. 1997). Some species are quite variable morphologically and subespecies are recognized. This is the case of E. paniculata Desf., a species with a wide distribution range in the Iberian Peninsula and North Africa. This species has habitat preferences restricted to marshes or areas close to streams, which result in populations appearing in isolated patches. In the Iberian Peninsula, E. paniculata was previously known from its southwestern quadrant (Benedí & al. 1997) until further explorations discovered some populations in the southeastern provinces of Murcia and Almería (Sánchez Gómez & al. 2006).
During recent fieldwork in the Sagres Peninsula of Portugal, two populations of Euphorbia with unclear identity were discovered. The general aspect resembled E. paniculata subsp. monchiquensis (Franco & P.Silva) Vicens, Molero & C.Blanché, but the leaves were clearly different, more similar to those of E. clementei Boiss.

MATERIAL AND METHODS
Some specimens were collected in order to be preserved in BCN, LISE and the personal herbarium of one the authors -U. Schwarzer-. Their morphology was compared to individuals of E. paniculata subsp. monchiquensis from populations in the southern Portugal and to herbarium specimens kept in BCN.

Taxonomic treatment
After examining the specimens and attending the existence of taxonomic characters to discriminate the studied individuals from other subspecies of E. paniculata we propose this new taxon:  fig. 3), from which it differs in its higher stature, growing as a slender bush with 3-4 woody stems up to 200 cm, leaves shorter and more elliptic to ovate -lanceolate in E. paniculata subsp. monchiquensis-. Especially when young, the leaves are densely covered with short hairs ( fig. 1)

Identification key for the subspecies of Euphorbia paniculata
The new subspecies can be inserted in existing taxonomic keys (Benedí & al. 1997) & al. 1990, but also in other habitats (Fox & Deil 2004 This taxon is restricted to places very close to seasonal water courses which have water only for a few hours during rainfall events. Within this microhabitat the plants occupy the first bank, about one meter above the bed of the water course. The habitat of E. paniculata subsp. calcicola subsp. nov. is close to the Atlantic Ocean, but plants occur only in sites at elevation higher than 10 m a.s.l. Due to the short length of the water courses one can find plants between 10 and 30 m a.s.l.
The geological ages of the localities are Early Miocene and Upper Jurassic. The plants grow in clayey soil as weathering product of the dominant limestone rock.
The origin of this subspecies could be explained (Vila-Viçosa & al. 2018) by the splitting of the distribution area of an ancestral form of E. paniculata, which potentially  (Carapeto & al. 2017); b, E. paniculata subsp. monchiquensis -yellow contour, approximate-with those localities checked for this work -red dots-, as well as those of E. paniculata subsp. calcicola U.Schwarzer & Vicens subsp. nov. -red dots within blue contour. occupied most of the southern Iberian Peninsula -Algarve and Andalusiaat the time of maximum glaciation in Europe -about 20.000 years-. At this time the area was occupied by the ancestors of the Euphorbio-Quercetum canariensis Woodland.