'Teucrium elymaiticum' (Lamiaceae): a new species for Flora of Iran

A new endemic species from western Iran, Teucrium elymaiticum Attar, Sotoodeh & Mirtadzadini, spec. nova is described. It belongs to section Scordium. Considering the combination of some characteristics like indumentum, bracts, pedicel, calyx, corolla size, and nutlet shape and size, the new species is related to T. scordium subsp. scordioides (Schreb.) Arcang.. The differences between these two species are highlighted. Images, distribution map and an updated identification key for the genus are presented.


Introduction
Teucrium L. is a large genus of Lamiaceae with more than 260 species in the world (Tutin & Wood 1972;Harley et al. 2004). This genus is distributed in the Mediterranean region, which is a major speciation center of the genus (Tutin & Wood, 1972;Cantino et al., 1992;Navarro & El Oualidi, 2000;Harley et al., 2004;Crespo et al., 2018).
Teucrium is distinguished from the other members of Lamiaceae by lack of corolla upper lip and nongynobasic style (Navarro & El Oualidi, 2000;De Martino et al., 2010). Based on the general habit of the plant, leaf type, calyx shape, and inflorescence structure, the genus has been divided into seven sections, six of them are included in the Flora Iranica (Rechinger, 1982).
A total of 19 taxa of Teucrium naturally occur in Iran, three of them are endemic which mainly grow in the Irano-Turanian region between 700 and 2000 m above sea level (Rechinger, 1982;Jamzad, 2012). Besides, T. persicum Boiss., a Saharo-Sinidian element, is present only at elevations of southern regions, and T. hyrcanicum L. (with bilabiate calyx), a hyrcanian element, grows in north of Iran. Some species like T. polium L. and T. orientale L., are widely distributed in steppes, arid, and semiarid regions of Iran (Eshratifar et al., 2011).
During a field trip to Ilam in 1996, a province located in western Iran, an interesting specimen of Teucrium was collected. A careful examination of the morphological features of the specimen revealed that it did not correspond with any of the previously described species and it was determined that the specimen is a new species to flora of Iran.
The aim of this paper is to provide a detailed morphological description, information on habitat, a distribution map of the new species, and its morphological relationship with its allied species. This new species is similar to Teucrium scordium subsp. scordioides (Schreb.) Arcang., but it differs by its indumentum, bracts, pedicel size, calyx length, corolla diameter, verticillasters and nutlet size and shape.

Material and Methods
The new species was found during a systematic revision of Teucrium specimens of Iran at Central Herbarium of Tehran University. The specimen was compared meticulously with different Iranian Teucrium, regional and non-regional collections in various European (G, K, P) and Iranian (IRAN, MIR, TUH) herbaria, and checked in several floras (Yuzepchuk, 1954;Tutin & Wood, 1972;Ekim, 1982;Rechinger, 1982;Jamzad, 2012).
In total, 10 quantitative and qualitative morphological traits were studied (Table 1). Indumentum, flowers and nutlets were photographed by Dino-Lite Handheld Digital Microscope AM413T. The general views of the plant were done with Canon PowerShot SX260 HS camera. All micro-measurements were done using integrated software of Dino-Lite Digital Microscope. A magnification of 35x has been used for photography of indumentum of leaves and calyx, and 186x for nutlets.
Etymology. The species name elymaiticum refers to the Elamite Empire (c. 1210 -1100 BC) where Ilam province is a part of.

Habitat, ecology and distribution
Teucrium elymaiticum occurs on rocky slopes at margin of xerophyte oak (Quercus brantii var. persica (Jaub. & Spach) Zohary) woodlands of Ilam province, near Darreh-Shahr, in West and South-West of Iran, ca. 1000 m a.s.l. (Figure 3). Being located in the western part of Zagros Mountains gives the province its special landscape which feature hot summers and mild winters and fairly high annual precipitations (about 400 mm) mostly in form of rain, although snow is not rare. The climate of the region is semi-arid, and the soil texture is mostly sandy loam and silt loam. Teucrium elymaiticum was found growing together with some species such as

Discussion
Based on some morphological characters, Teucrium elymaiticum belongs to section Scordium Boiss., with affinities to T. scordium subsp. scordioides. This section is characterized by being perennial and stoloniferous herbs and having toothed leaves, like T. scordium and T. melissoides from Iran (Rechinger, 1982;Ekim, 1982).
The new species has some unique and remarkable features among the 19 species of Iranian Teucrium such as difference in nutlet shape and size, dense indumentum, short bracts and dense verticillasters. It shares some characteristics with two other species in the section Scordium, and it is mostly similar and related to T. scordium subsp. scordioides in habit, but it is an isolated species in this section. The specific differences among both species are indumentum, bracts, pedicel size, calyx length, corolla diameter, verticillasters, nutlet size and shape (Table 1, Figures 1 and 2). Special emphasis has been placed on differences in indumentum type, nutlet size and shape, three important taxonomic characters in species classification in the genus Teucrium (Navarro & El Oualidi, 2000;Eshratifar et al., 2011). They indicate considerable differences between these two related species and they confirm that the new species is different from all other Teucrium taxa previously described for Iran. As a consequence, an updated key on Iranian Teucrium, including the new species and taking into account the results of Flora Iranica by Rechinger (1982), is provided: