Potentilla alborzensis Faghir & Attar, 2021

Faghir, Marzieh Beygom, Sadeghi, Samira & Attar, Farideh, 2021, A new species of the genus Potentilla L. (Rosaceae) from the Tehran province (Iran), Adansonia (3) 43 (9), pp. 99-106 : 100-104

Potentilla alborzensis Faghir & Attar , sp. nov.

( Figs 1-3 ).

Distinguished from P. adenophylla Boiss. & Hohenack. by its erect (vs prostrate) stem, covered by long crispate (vs short and long straight) flexuose hairs, 3-5 (vs 5-7)-foliolate radical leaves, petals 8-10 mm (vs 10-20 mm) long, pollen grain prolate P/E = 1.45 (vs subprolate P/E = 1.19).

TYPUS. — Iran. Tehran province, Firouzkuh, Tang-e Washi , 21.VII.2017, Attar, Zamani & Habibi 48569 (holo-, GUH [ GUH8030 ]!; iso-, TUH!) .

DISTRIBUTION AND ECOLOGY. — The new species was collected from Tehran province, Firouzkuh, Tang-e Washi, 35°28’N, 52°46’E, 1731 m a.s.l., ( Fig. 4 ). It grows on dry steppe mountains area. Potentilla alborzensis Faghir & Attar , sp. nov. grows on bare rocks and boulders near the river, at about 1.5 to 2 meters above the water surface, accompanied by only a few lithophytic species e.g. Parietaria judaica L. and Graellsia integrifolia (Rech.f.) Rech.f. However, we found several populations of Hypericum perforatum L., H. scabrum L., Cirsium hygrophilum (Greene) Jeps. , Heracleum persicum Desf. ex Fisch. , Epilobium montanum L., Centaurea aucheri (DC.) Wagenitz , Drymocallis poteriifolia (Boiss.) Soják and Potentilla balansae Soják. ( Faghir et al. 2010a) in the stony slopes, open meadows, and along the riverside.

CONSERVATION STATUS. — We categorized Potentilla alborzensis Faghir & Attar , sp. nov. as Endangered (criteria EN) according to criteria B1 (indicating the extent of occurrence, less than 5000 km 2), subcriterion a (severely fragmented or known to exist at no more than five locations); criterion B2 (indicating by area of occupancy, less than 500 km 2), subcriterions a (grows at no more than five locations) and b (comprising of mature individuals); criterion D (total number of individuals does not exceed 200 mature individuals) (IUCN 2019). The population of this new species is endangered by the following factors: risk of flooding with a basic rocks destruction and extinction due to tourism in the region, especially in summer, when the favorable climate and beautiful natural waterfalls attract many tourists. Endangered: B1a; B2a; D.

DESCRIPTION

Perennial herbs; caudex sturdy, erect-ascending, multicipital, densely covered with brown remains of stipules ( Fig. 1 ); stems 12-20 cm long, slightly branching, having long crispate flexuose hairs ( Fig. 2A ); radical leaves and dead stipules on stock polystichous; radical leaves mainly 5-foliolate, rarely 3-foliolate, 8-10 × 12-15 mm, leaflets subsessile, obovateoblong, cuneate, obtuse, with 5 pairs of oblong acute teeth, both sides hairy (long flexuose trichome) ( Fig. 2B-D ) and glandular; petiole of radical leaves 2.5-4 cm long, having appressed-subappressed hairs ( Fig. 2E ); stipules of radical leaves lanceolate; lower cauline leaves 5-foliolate, petiolate; upper cauline leaves 3-foliolate with short-petiole; stipules of cauline leaves lanceolate with 1 tooth ( Fig. 2F ); inflorescence a lax corymb; flowers 10-15 mm in diameter ( Fig. 2G- I) ; pedicel long and thin; sepals hairy and glandular, erect ( Fig. 2G ), patent in mature flower ( Fig. 2I ); outer sepals oblong-linear, obtuse, 5×12.5- 3 mm; inner sepals almost as long as outer ones, ovate-lanceolate, acute; petals 8-10mm, obovate, emarginate yellow ( Fig. 2J ); stamens 20; receptacle conoid, hairy; style subterminal, shorter than fruitlets; stigma dilated, clavate and papillate ( Fig. 2K ); achene ovoid, smooth ( Fig. 2L ).

Leaf and calyx micromorphology

Leaf and calyx micromorphological data revealed straight flexuose (villose), subappressed, hairs and small glandular trichomes having a 1-2 celled stalk and single head, on both surfaces of the leaves ( Fig. 3A ) and adaxial surface of the outer and inner sepals ( Fig. 3B ).

Pollen morphology

Pollen grains are monads radially symmetrical, isopolar, trizonocolporate, polar axis length (P) = 28.4-30.89 µm, equatorial axis length (E) = 18.33-22.5 µm, P/E = 1.45, prolate in shape and medium in size. The outline of the pollen grains is elliptical in equatorial view ( Fig. 3C ) and triangular in polar view ( Fig. 3D ). The exine sculpturing is striate in this species.

TAXONOMIC REMARKS

The features that distinguish the new species are the indumentum types of stem and petiole of radical leaves, the shape of basal and cauline leaves and their stipules, the sepal shape and petal length. The new species was found as isolated populations on rocks and boulders, without any other species of Potentilla growing with it. It appears that P. balansae Soják is geographically the closest species to P. alborzensis Faghir & Attar , sp. nov. However, the two species show great differences in terms of ecology and morphological evidences especially style morphology, hair types and leaf shape. Therefore, the participation of P. balansae (having a long style characteristic of the section Persicae) in the origin of P. alborzensis Faghir & Attar , sp. nov. is less likely. Moreover, the morphological traits of the new species do not show any variability within a population. According to Soják (2006), worthy of attention are especially those species morphologically isolated and without any obvious close relationship, which are thus rather unlikely of hybrid origin

The new species is close to P. crantzii (Crantz) Beck ex Fritsch and P. adenophylla Boiss. & Hohenack. in the Flora of Iran. The two latter species are classified in the section Aureae (Th. Wolf) Juz. ( Yuzepchuk 1941), comprising four representatives in the area covered by Flora Iranica (Schiman-Czeika 1969) and four species in the Flora of Iran (Khatamsaz 1992). They prefer alpine meadows, ravines, forest edges, stony slopes, limestone rocks and gravels of Hyrcanian and Irano- Turanian regions of N, NW of Iran (Schiman-Czeika 1969; Khatamsaz 1992). Palmate radical leaves, covered with straight hairs (not tomentose) and glandular trichomes; corymbiform inflorescence; hairy and glandular sepals; clavate and papillose style, shorter than or as long as matured ovary are important characteristics of the section Aureae ( Yuzepchuk 1941; Schiman-Czeika 1969; Khatamsaz 1992). Among them, P. gelida C. A. Mey. and P. geranioides Willd. distinctly differ from P. alborzensis Faghir & Attar , sp. nov. in terms of their leaves characteristic features especially number, shape, trichome type and dentation of the leaflets, as well as the shape of outer and inner sepals; flower size; sepals and petals of the same height (Table 2, columns 5 and 6). The new species shows affinities with P. crantzii and P. adenophylla by upper surface or both sides of radical leaves glabrous, shallowly divided; larger flower in size and petals longer than sepals (Schiman-Czeika 1969; Soják 2012). P. crantzii grows in stony rock streams, ravines, meadows, forest edges of N, NW of Iran. It is well known for its distichous radical leaves and dead stipules on stock; mainly 5-foliolate, obovate-cuneate or suborbicular leaflets, having 2-5 pairs of teeth; entire stipule of cauline leaves; oblong-elliptical, obtuse outer sepals; ovate- oblong inner sepals; petals twice longer than sepals ( Table 1 [column 2]). While, P. adenophylla is distributed in alpine and subalpine meadows (1800 m a.s.l.), stony slopes, limestone (Khatamsaz 1992). The latter species is characterized by its 5-7 foliate radical leaves, leaflets having 3-6 pairs of teeth; petiole of the radical leaves with short and long hairs; stipule of the cauline leaf lanceolate, obtuse entire; outer sepal linear-lanceolate; inner sepal ovate-lanceolate, sepals of the same height and petal longer than sepals ( Table 1 [column 3]). In addition, the current SEM observations revealed leaf micromorphological features of P. alborzensis Faghir & Attar , sp. nov., especially hairs and glandular trichomes are identical to those of P. adenophylla (straight, subappressed hairs) ( Faghir et al. 2010a). Palynological evidences of the new species are also in consistency with the two latter species, having striate exine sculpturing with short ridges interval and similar pollen size (small to medium). However, the pollen shape of P. alborzensis Faghir & Attar , sp. nov., varied from the two allied species (spheroid-prolate, P/E = 1.06, in P. crantzii and subprolate P/E = 1.19, in P. adenophylla ). Based on the previous study, the pollen shape is useful for separating some sections, but shows changes in others including sect. Aureae ( Faghir et al. 2012). Based on morphological diagnostic characters ( Yuzepchuk 1941; Schiman-Czeika 1969; Peşemen 1972; Khatamsaz 1993; Soják 2012) an identification key is presented:

Figures

FIG. 1. — Potentilla alborzensis Faghir & Attar., sp. nov. From holotype: Attar, Zamani & Habibi 48569 (TUH).

FIG. 2. — Details of morphological characters of Potentilla alborzensis Faghir & Attar., sp. nov. (Attar, Zamani & Habibi 48569): A, stem surface; B, radical leaves; C, leaflets lower surface; D, leaflet upper surface; E, petiole of radical leaf; F, upper cauline leaves and stipules; G, flower with erect sepals; H, flower from outer view; I, flower from inner view; J, petal; K, carpels with style and stigma; L, achene. Scale bars: A,-F, H 0.5 mm; G, I-K 1mm; L 2 mm.

FIG. 3. — Micrographs of Potentilla alborzensis Faghir & Attar., sp. nov. from (Attar, Zamani & Habibi 48569): A, leaf upper surface; B, outer sepal upper surface; C, pollen from equatorial view; D, pollen from polar view. Arrows indicate glandular trichomes. Scale bars: A, 50 µm; B 100 µm; C, D, 10 µm.

FIG. 4. — Distribution map of Potentilla alborzensis Faghir & Attar., sp. nov.