Potentilla diversidentata Faghir & Naqinezhad, 2019

Naqinezhad, Alireza & Faghir, Marzieh Beygom, 2019, Two new species of the genus Potentilla (Rosaceae) from North of Iran, Phytotaxa 392 (4), pp. 291-300 : 295-298

Potentilla diversidentata Faghir & Naqinezhad sp. nov. ( Figs. 3 & 4)

Type:— IRAN: Mazandaran province: Sari, Sangedeh, Neru mountain , 35º 59 ʹ 1.81 ʺ N, 53º12 ʹ 53.98 ʺ E, 2700 m, 21 July 2016, A. Naqinezhad & H. Gholizadeh 7606 ( HUMZ!; isotype: GUH!) .

FIGHURE 4. Potentilla diversidentata (holotype; 7606- HUMZ); A. Habit in situ ; B –. Radical leaf ; b cauline leaves; C. Terminal leaflet upper surface ; D. Tridentate lateral leaflet upper surface; E Tridentate lateral leaflet lower surface ; F. Stipule of radical leaf from dorsal side ; G. Stipule of radical leaf from ventral side ; H. Flower ; I. Petal ; J. Flower from inner view ; K. Flower from outer view ; L. Styles. Arrow indicates different leaflets of the radical leaf: red: terminal, blue: lateral and black lower leaflets .

Plant perennial, caespitose ( Fig. 3 and 4 A); caudex sturdy, woody, densely covered brown relics of stipules; stems lateral; radical leaves digitate, 5-foliate (Fig. 4 B), unequally dentate at apex; obovate, cuneate at the base; leaf surface sericeous-silvery, trichome long dense straight appressed on both sides (Fig. 4 C – E); 18–20 × 25–30 mm; radical leaves comprises one terminal (14–15 mm long, 13–14 mm wide), two lateral (13.8–15 mm long, 10–11mm wide) and two lower leaflets (11–13 long, 9.5–11 mm wide); terminal leaflet with 5 teeth (Fig. 4. B, red arrow), two narrow in the middle and three adjacent (Fig. 4 C); of the two lateral leaflets one with three (Fig. 4 D– E) and the other with five teeth (Fig. 4 B, blue arrows); lower leaflets with five irregular teeth (Fig. 4 B, black arrows); petioles of radical leaves 8–9 cm long, 2.5 mm wide, densely hairy, trichome appressed, villous; stipule of radical leaves 26–28 mm long, 6.5–7 mm wide, ventral auricles free, ovate-lanceolate, 5–6.5 mm long, orange-red color, both dorsal (Fig. 4 F) and ventral sides (Fig. 4. G) with long straight trichome; cauline leaves ternate, triangular-cuneate, tridentate, teeth 3–3.5 mm long; leaflets 10–12 mm long, 3–4mm wide; petiolate (Fig. 4 B); flowering stem ascending, longer than basal leaves, 4–8 cm long, covered with dense villous hairs; flower solitary, 12–15 mm in diameters (Fig. 4 H – K); 1–2 in number; pedicels 25–40 mm long; calyx triangular-lanceolate, 6–6.5 mm long, 2.5–3 mm wide, densely villous on adaxial side, reddish abaxial side and margins; epicalyx 4–5 mm long, 2–2.5 mm wide, oblong-linear, obtuse, densely villous on both sides; petals yellow, broadly obovate, 9.5–13 mm long (Fig. 4 I); style sub terminal, not thickened at the base, filiform, yellow in color, 5.5–6.7 mm (Fig. 4 L); stigma dilated; stamens ± 20 in two rows of 10, anther ovate; achene brown color, with smooth, scantily veined surface, 10 mm long and 10.3 mm wide.

Distribution and ecology:— Potentilla sangedehensis and Potentilla diversidentata grow mainly on basic rocky cliffs and outcrops in the high montane grasslands and open woodlands (2700–2800 m a.s.l.) in the Central Hyrcanian region, north of Iran. They were accompanied by Betula pendula Roth , Sorbus aucuparia L., Cotoneaster nummularius Fisch. & C.A.Mey. , Polystichum lonchitis (L.) Roth, Primula matthioli K. Richt. , Peucedanum hyrcanicum Gholizadeh, Naqinezhad & Mozaff. , Acer hyrcanum Fisch. & C.A.Mey. , Quercus macranthera Fisch. & C.A.Mey. ex Hohen. ( Gholizadeh et al. 2017) and Alchemilla mazandarana (Naqinezhad et al. 2017).

Etymology: —The specific epithet of P. sangedehensis refers to Sangedeh village in the high mountain areas of the Central Hyrcanian forests, North of Iran while epithet of P. diversidentata refers to diversity in number leaf teeth of the specimens.

Phenology: —Flowering and fruiting in June–August.

Taxonomic remarks: — Potentilla sangedehensis is distinguished from its allied species by its 5-foliate tridentate, obovate, truncate leaflets, epicalyx shorter than calyx, petal yellow with brown spot at the base and rotundate, with short claw ( Table 1). The new species is close to a group of three species comprising P. collettiana Aitchison & Hemsey (1880: 53) , P. curviseta Hooker (1878: 358) and P. pteropoda Royle (1835: 207) by its general habit and caespitose thick rootstock. Three later species are classified in the section Curvisetae (Th. Wolf 1908: 94) Schiman-Czeika (1969: 87) ( Juzepczuk 1941; Soják 2006, 2012). P. collettiana is an endemic species of Afghanistan ( Soják 2012) and resembles to P. sangedehensis by having, ternate, digitate, and silvery-sericeous; tridentate leaflets; dense pilose immature carpel and golden yellow petal. However, it differs from the new species with its 10–50 (–60) mm, obovate-oblong leaflets; 1–2 cm petiole; ovate-lanceolate epicalyx; notchless petal ( Table 1). Potentilla curviseta and P. pteropoda are growing in the Himalayan Mountains ( Soják 2006). The former species resembles to either of P. sangedehensis and P. collettiana for its tridentate leaflets. Nevertheless, linear cuneate leaflets with sparsely or moderately hairy surfaces, longer petiole (3–7 cm), lanceolate acuminate calyx and oblong epicalyx obovate emarginated petal forms distinguishing characters of P. curviseta ( Table 2). P. pteropoda is separated from P. sangedehensis , based on its oblong leaflets, with 2–4 pairs teeth, oblong elliptical calyx, ovate acute epicalyx, obcordate petal ( Table 2). Based on the diagnostic characters given in the table and text, the following identification key is presented:

1 Radical leaves 5-foliate, tridentate, silvery-sericeous; petal with claw..................................................................... P. sangedehensis

- Radical leaves 3-foliate with tri and more teeth, silvery-sericeous, sparsely or moderately hairy; petal without claw....................2

2 Leaflets tri-dentate; calyx lanceolate..................................................................................................................................................3

- Leaflets with 2–4 pairs of teeth; calyx oblong elliptic, obtuse........................................................................................ P. pteropoda

3 Leaves 10–50 (–60) mm long, obovate-oblong in shape, silvery-sericeous; petiole 1–2 cm; epicalyx ovate-lanceolate, as long as calyx; petal not emarginated............................................................................................................................................ P. collettiana

- Radical leaves leaflet 13–25 mm long, linear-cuneate in shape, sparsely or moderately hairy; petiole 3–7cm; epicalyx ovate-lanceolate, much shorter than calyx; petal emarginated.................................................................................................... P. curviseta

Potentilla diversidentata has long style, characteristics of section Persicae (Th. Wolf 1908:421) Juzepczuk (1941: 175) , the largest section of the genus Potentiall in Iran, including 14 species and 12 endemics ( Faghir et al. 2011). Unequally dentate leaflets (5 teeth on terminal, 3 to 5 on lateral and 5 irregular teeth on lower leaflets); shorter flowering stem (4–8 cm), a few number of flower (1–2), long pedicel (25–40 mm); triangulare-lanceolate calyx; oblong-linear obtuse epicalyx and broadly obovate notchless entire petal are the most outstanding diagnostic traits of P. diversidentata (Table 3). The new species resembles to two Iranian endemics, P. pannosa Boissier & Haussknecht (1872: 719) (Syn: P. pannosa var. pannosa ) and P. petraea Schlechtendal (1816: 292) , growing in alpine areas of northern and northwestern Iran ranging from 1900 to 4000 m a.s.l. ( Schiman-Czeika 1969, Pesmen 1972, Khatamsaz 1993, Soják 2012). The two latter species have similar dense straight appressed or hirtellous hairs ( Faghir et al. 2010a) as well as 5-foliate leaves as it is observed in P. diversidentata . P. pannosa resembles to P. diversidentata for having similar radical leaflets shape (obovate, cuneate at the base); petal color (yellow); almost identical number of flower inflorescence (2–3) and style color (yellow). Nevertheless, it is distinguished from, P. diversidentata by its entire, sessile cauline leaf; shorter pedicle (4–8mm), ovate, acute calyx, elliptical oblong obtuse epicalyx, broadly obovate emarginated petal (Table 3).

Ternate, petiolate cauline leaflets are the two main similarities between P. diversidentata and P. petraea . However, its white (with purple veins), obovate emarginated petal and red style can easily detect the later species. Furthermore, longer flowering stem (10–17 cm), more number of flower (10–12), ovate obtuse calyx, broadly ovate epicalyx are other diagnostic traits found in P. petraea (Table 3).

Potentilla diversidentata shows certain affinities with P. porphyrantha Juzepczuk (1940: 48) especially for its leaflets shape (obovate cuneate at the base) and tridentate cauline leaves. However, the latter species is characterized with sessile cauline leaves, much longer flowering stem (6–20 cm), multiflorate inflorescence (18–20), linear-lanceolate calyx, ovate-lanceolate epicalyx, pink or pale purple, cuneate-obovate petal and red style. The distinguishing characters of Potentilla diversidentata and its allied species are given in the following key:

1 Radical leaves unequally dented (terminal leaflet 5 teeth; lateral leaflets 3 to 5 and lower leaflets having 5 irregular teeth), flowers 1–2 in number, petal yellow in color ......................................................................................................................... P. diversidentata

- Radical leaves equally dented, flowers 2 or up to 15 in number; petal yellow, white and pink in color...........................................2

2 Petal yellow, flowering stem 5–10 cm, flower 2–3 in number; style yellow, cauline leaf entire, sessile, pedicle 4–8 mm, style yellow ................................................................................................................................................................................. P. pannosa

- Petal white and pink in color; flowering stem 10–20 cm, flower up to 15 in number, cauline leaf tridentate; sessile or petiolate, style red…………………………………..…………………..….3

3 Petal white, with purple veins; emarginate obovate; cauline leaf petiolate; calyx ovate, obtuse; epicalyx broadly ovate, pedicle 12–14.3 mm ……………………………..…..………. P. petraea

- Petal pink or pale purple, notch less, cuneate-obovate; cauline leaf sessile; calyx linear-lanceolate; epicalyx ovate-lanceolate, pedicle 18–20 mm ………………………. P. porphyrantha

Conservation status:— Potentilla sangedehensis and P. diversidentata should be evaluated as critically endangered (CR) based on IUCN (2012). The new species fulfils criterion B1 that is indicated by extent of occurrence, less than 100 km 2. It also fulfils sub criterions a (severely fragmented or known to exist at only a single location) and b (continuing decline, observed, inferred or projected in extent of occurrences, number of locations or subpopulations and number of mature individuals). Moreover, the species fits with criterion B2 which is indicated by area of occupancy, less than 10 km 2. It also fulfils sub criterions a (severely fragmented or known to exist at only a single location) and b (continuing decline, observed, inferred or projected in extent of occurrences, number of locations or subpopulations and number of mature individuals). Furthermore, the estimated total number of individuals does not exceed 50 mature individuals (criterion C).

Figures

FIGURE 3. Potentilla diversidentata (holotype; 7606-HUMZ)