Astragalus durandianus Aitch. & Baker

Ghahremaninejad, Farrokh, Joharchi, Mohammad Reza & Memariani, Farshid, 2022, Astragalus durandianus (sect. Trachycercis) as an Iranian endemic species: emended description, distribution, and conservation, Phytotaxa 550 (1), pp. 32-44 : 33-43

Astragalus durandianus Aitch. & Baker , Trans. Linn. Soc. London, Bot. 3: 54. 1888. Emend. F.Ghahrem.

( Figs. 1–6).

Lectotype (Podlech, Sendtnera 6: 179. 1999): Khorassan, on the pass to the south of Bezd , [35.21° / 60.44°], 6000’, 18.6.1885, J.E.T. Aitchison 688 (K photo! [ K001094452 ] ; iso: BM photo! [ BM000885251 ], C photo! [ C 10011702 ], FI photo! [FI010702], G, GH photo! [ GH00059546 ], LE! [ LE00013954 ], P! [ P 03202941 ], W! [ W19590010612 ]) .

Perennial, 4–17(–20) cm tall undershrub, caespitose, covered in vegetative parts with warty, ± medifixed, ascending to partly spreading white hairs up to 1 mm. Rootstock up to 10 mm thick, repeatedly divided, with short subterranean branches, in upper part covered with blackish remnants of old stipules. Stems of the current year, if present, up to 4 cm, very densely covered with subappressed to ascending, tangled white 0.6–0.8 mm hairs, at the nodes sometimes mixed with black hairs. Stipules whitish, green to yellow, 3–5 mm, narrowly triangular, adnate to the petiole for 1–2 mm, loosely to densely covered with subappressed to slightly ascending white 0.4–0.7 mm hairs, at the base sometimes with loosely black hairs mixed in. Leaves 2.5–6.0 cm; petiole 0.8–30.0 mm, like the rachis rather densely to densely hairy. Leaflets in 3–5 pairs, obovate, or rarely elliptic, 4–14 × 2–6 mm, rounded to emarginate, on both sides rather densely covered with ascending to nearly spreading hairs up to 1 mm, mostly flat. Peduncles very short to 7 cm, white hairy to white hairy at the lower part and black hairy at higher part, loose to dense, subappressed to ascending. Raceme 1–3- flowered. Bracts 1.5–3.0 mm, narrowly triangular, densely covered with white, predominantly white or completely black hairs, ciliate with white hairs. Pedicels 1.0– 3.5 mm, black hairy. Calyx 10.0– 18.5 mm, tubular, at the base slightly gibbous, rather densely covered with asymmetrically bifurcate, ascending, often flexuose, tangled white and black hairs or completely black hairs, 0.5–1 mm; teeth narrowly triangular, 1–4 mm, densely white hairy on inner side. Petals purple and white. Standard 24–33 mm; blade ovate to obovate, 9.5–13.0 mm wide, emarginate, narrowed into the narrow claw. Wings 23–28 mm; blades narrowly oblong, obliquely emarginate, 9.0–10.5 × 2.5–3.5 mm; auricle c. 1 mm, claw 14–18 mm. Keel 20.5–25.0 mm; blades obliquely elliptic to obliquely elliptic–triangular, subacute, 6.5–8 × 3–4 mm; auricle c. 0.4–0.5, claw 14–17 mm. Stamen-tube 16–22 mm, truncate at the mouth. Ovary stipitate (stipe c. 1 mm), 5.5–7.5 mm, linear, appressed white hairy; style 14.5–18.0 mm, hairy only at the base, with minutely papillose stigma (0.4–0.5 mm). Legumes sessile, or with a stipe to c. 0.8 mm, ovoid-inflated, 18–35 mm long, 10–20 mm high, 12–28 mm wide, shallowly grooved ventrally and dorsally, subacute, nearly fully bilocular; valves thin, straw-colored to pale brownish, densely covered with ± medifixed, ascending, flexuose, tangled white to rarely together with black hairs 0.1–0.3 mm and loosely with white extremely asymmetrically bifurcate, straight, ascending to spreading hairs 2–3 mm. Seeds 2.5–2.8 × 2.8–3.2 mm, pale brown, with darker dots.

Specimens examined

A list of all specimens of A. durandianus examined in this paper (from several herbaria) or recorded in related literature (i.e., Podlech et al. 2011, Podlech & Zarre 2013, Maassoumi 2018) is indicated here. All recorded specimens of this species are collected from Iran. Three specimens from the list below have not been seen (no. 4, 28, 29: BG, G) by the authors of this article, and therefore they are not marked with “!” sign in front of the herbarium acronym; but some of their data such as elevation, phenology, and the locality have been used in our analysis. Among these 31 specimens, only five (no. 22 to 26: all deposited in FUMH) are collected in flowering time and the rest are in the fruiting stage.

— IRAN. Khorassan Provinces: (1) On the pass to the south of Bezd , 1830 m, 18.6.1885, Aitchison 688 (BM photo!, C photo!, FI photo!, G, GH photo!, K photo!, LE!, P!,W!); (2) 27 km S Bejestan [Bajestan] versus Ferdows , 1700–1750 m, 10.5.1975, Rechinger 51516 (M, W!); (3) Between Birjand and Torbat , 3.7.1950, Manuchehri 5590–E (W!); (4) Inter Assadabad et Zaidan , 33°10’ N, 60°05’ E, 1600–1700 m, 1.6.1977, Rechinger 56103 (G); (5) N Kashmar, 12 km NE Rivash, 35°25’ N, 58°25’ E, 2000 m, 5.5.1975, Rechinger 51281 (W!); (6) 27 km S de Bajestan, 1700–1750 m, 10.5.1975, Iranshahr 44159 ( IRAN!); (7) NW Qayen, Dehestan, 6 km on the road towards Karqand, 1700 m, Rafeie 17162 (FUMH!); (8) NW Qayen, Grimonj to Bihood, km 12, 1750 m, Rafeie 27115 (FUMH!); (9) 18 km from Qayen to Birjand, 1930 m, Maassoumi et al. 83335 (TARI!); (10) Gonabad, Seno, Darre Nakhoo, 16.5.1991, 1600 m, Faghihnia & Zangooie 19572 (FUMH!); (11) 42 km from Kashmar to Neishabur, Akbarabad pass, 2000–2100 m, Amirabadi & Abbasi 4377 (TARI!); (12) W Gonabad, Boghchir ( Black Mt. ), 2500 m, 17.5.1995, Rafeie & Zangooie 25108 (FUMH!); (13) NW Qayen, Khezri, Piremardanshah, 1700 m, 13.5.2003, Joharchi 34466 (FUMH!); (14) N Kashmar, SE Rivash , the mountains of S Tanurcheh, 1962–2000 m, N 35°23’7.4” E 58°37’28.6”, 27.5.2012, Joharchi 44816 (FUMH!); (15) Qayen-Gonabad road, near Khezri, Piremardanshah, 1700 m, 19.5.1986, Ayatollahi & Zangooie 14380 (FUMH!); (16) 26 km from Kakhk to Ferdows, 1900 m, 21.5. 1997, Rafeie & Zangooie 28682 (FUMH!); (17) Between Gonabad and Ferdows, Tangale Mahvid, 1850 m, 11.5.1998, Rafeie & Zangooie 30651 (FUMH!); (18) 30 km from Qayen to Birjand, 17.5.1986, Ayatollahi & Zangooie 14221 (FUMH!); (19) Qayen to Birjand, after Khunik pass, 1850 m, 11.6.1989, Joharchi, Zangooie & Alvani 17640 (FUMH!); (20) 95 km N of Mashhad, NW Mareshk, Hezar-Masjed Mts., 2500 m, 24.6.1996, Faghihnia & Zangooie 27565 (FUMH!); (21) S Gonabad, elevations around Boskabad dam, 2000 m, 3.5.1999, Hojjat & Zangooie 32262 (FUMH!); (22) N Kashmar, NE Chelpo village, on serpentine and gypsum hills, N 35°37’28.8” E 58°33’05.5”, 1940–2100 m, 26.4.2017, Joharchi & Memariani 46031 (FUMH!); (23) 30 km south of Gonabad , Kalat Mts. , 1700 m, 15.4.1985, Joharchi & Zangooie 11950 (FUMH!); (24,25) NW Qayen, Khezri, mountains around of Boskabad dam, 1900 m, 2.5.1995, Faghihnia & Zangooie 25256, 25270 (FUMH!); (26) 21 km from Gonabad to Ferdows, 2200 m, 25.4.1995, Rafeie & Zangooie 25045 (FUMH!); (27) E Birjand, 90 km on the road towards Darmian, 2000 m, 15.4.1981, Zokaei & Ghoreshi 478 (FUMH!).– Mazandaran Province: (28) Nezva Kuh, at the western top, northern side, 53°10’ E, 35°59’ N, 3200 m, 8.7.1959, Wendelbo 1288 (BG).– Semnan Province: (29) Declivia austr. montis Shahvar supra Nekarman (supra Rahé), 3500 m, 20.– 26.7.1948, Rechinger 5963 (G); (30) Kuh –i Nezva, 3000 m, 29.8.1948, Behboudi & Aellen 5593–E (W!); (31) 30 km NW Shahrud, Mt. Shahvar above Tash, 3000 m, 11.7.1976, Assadi & Maassoumi 21074 (TARI!).

Diagnosis:—The closest species to A. durandianus are A. shebarensis and A. pseudoshebarensis . However, it differs with its relatives in having leaflets with 4-10 mm long (not 2–5 mm long), leaf covering with ascending to nearly spreading hairs (not covering with appressed hairs), peduncles length from very short to 7 cm long (not 0.2- 3 cm long), legumes with 18–35 mm long (not 15-25 cm long).

Phenology:—The elevation range for A. durandianus is from 1600 m (South Khorassan Province) to 3500 m (Semnan Province). At the elevation of 3000–3500 m in Mazandaran and Semnan Provinces, the fruiting time is late, i.e. early July to late August. Therefore, the fruiting time range is estimated around July to September. In 1600–2500 m elevation and probably lower elevations in Khorassan Provinces, the fruiting time is earlier, i.e. early May to July. Therefore, the fruiting time range can be estimated around late April to September .

Taxonomic relationship:—Our follow–accepted list of the Iranian species of Astragalus sect. Trachycercis is almost entirely consistent with Podlech and Zarre (2013). The only difference is that there is one more species in our list, i.e. A. barnasariformis Maassoumi, F.Ghahrem. & Bagheri in Bagheri et al. (2011: 178): 1) A. barnassari Grossheim (1940: 32) , 2) A. barnasariformis (endemic to Iran), 3) A. durandianus (endemic to Iran), 4) A. poliotrichus Bornmüller (1914: 379) (endemic to Iran), 5) A. pseudoshebarensis Podlech (2004: 594) (endemic to Iran), and 6) A. testiculatus Pallas (1800: 82 , t. 67).

A triplet species group in this section, including A. durandianus (endemic to Iran), A. shebarensis Podlech (1973: 274) (endemic to Afghanistan), and A. pseudoshebarensis Podlech (endemic to Iran) have swollen fruits with completely distinct separated (not overlapped) habitats; however, they are morphologically related and similar to each other and with somewhat overlapping characters. These species grow in a restricted area and can be considered vicariant species. Thus, here it is proposed, two species, i.e. A. shebarensis and A. pseudoshebarensis , may be synonyms as subspecies of Astragalus durandianus . Proof of this claim requires the study of several specimens of these species in flower and fruit states and perhaps additional complementary studies such as molecular researches. The petals characteristics of A. pseudoshebarensis are not included in the descriptions (like A. durandianus in the original description), but the petal characteristic of A. shebarensis (based on Podlech & Zarre 2013, Maassoumi et al. 2005) is so similar to A. durandianus based on the observed flowers in some specimens in FUMH that is mentioned in this paper.

So far, no photos of flowering specimens of A. durandianus have been published in the form of articles, books, or even at virtual herbaria. The photos in this paper are from both herbarium specimens and natural individuals ( Fig. 3 ). In addition, flower components are also shown here, and photos of the plants that bear flowers in their natural habitat are unique and presented for the first time.

It should be noted here that in RBGE virtual herbarium, two flowering specimens are determined as A. durandianus . These two specimens were determined by Podlech (year 1996) as A. durandianus . Both specimens were collected from Afghanistan: (1) Bamian: Top of Hajigak pass, 3550 m, 25.6.1962, Hedge & Wendelbo 4619 (BG, E photo! [E00341210] (https://data.rbge.org.uk/herb/E00341210)), and (2) Ghazni: In monte Saperlebuli ad marginerm austro-orientalem altoplanitiei Dasht-i-Nawar, 3200–4200 m, 19.7.1967, W.Rechinger 37321 (E photo! [E00341209] (https://data.rbge.org.uk/herb/E00341209), G, M). Some years after these determinations, A. shebarensis Podlech was introduced as a new species ( Podlech 1973). These two RBGE specimens are mentioned as specimens examined for A.shebarensis in Podlech & Zarre (2013). Therefore, it is recommended that these determinations be changed in E Herbarium.

Distribution: —In the original description, A. durandianus was recorded from Bezd Mountains which is located in NE Iran. However, Aitchison (1888) described this species among several species collected from Afghanistan and on the label of type specimen in Paris herbarium “P”, it is noted as “ Plantes de l’Afghanistan ”. A label affixed to this specimen by F. Ghahremaninejad in 2013 indicates that this plant specimen belongs to the Iranian territory ( Fig. 1 ). Based on current data, A. durandianus is a Central Irano-Turanian species known as an Iranian endemic plant. Its distribution range covers mainly the eastern and northeastern Iranian mountains in the South Khorassan Province and Khorassan-Kopet Dagh (KK) floristic province in the Razavi Khorassan Province (28 specimens), with few localities in the alpine zone of eastern Alborz Mountains (three specimens) ( Fig. 7 ).

Based on current data, A. barnasariformis , A. poliotrichus , and A. pseudoshebarensis are the other Iranian local/ narrow endemic species of the sect. Trachycercis restricted to the central Iranian highlands; however, A. shebarensis is endemic to east-central Afghanistan. A. barnassari is a sub-endemic species restricted to the Caucasian (Atropatene) and Alborz Mountains. It is distributed mainly in the northwestern and northern Iran with few localities in the south of Azerbaijan, northeast of Iraq, and east of Turkey near the borders to Iran ( Fig. 7 ). A. testiculatus is a widespread species distributed from eastern Euro-Siberian to the eastern Irano-Turanian regions. It occurs in its southernmost distribution range in Khorassan-Kopet Dagh floristic province (sensu Memariani et al. 2016, Memariani 2020).

Conservation: —The conservation assessment of A. durandianus based on available data on the geographic range in the form of either extent of occurrence (EOO= 145951 km 2) or area of occupancy (AOO= 25000 km 2) shows that it does not belong to any threatened category and it is evaluated as Least Concern (LC) ( Fig. 8 ). Although it is a relatively widespread species based on geographic criteria for Red Listing ( IUCN 2019), it is not an abundant species in the natural habitats and may be qualified for a threatened category in the future. So, it is recommended to monitor and measure the population size over time and to check the current occurrence of the old collections, especially for the peripheral localities across its distribution range to re-evaluate the conservation status. It may be a potential ornamental plant due to its growth form, flowers, and fruits ( Figs. 3–4 ). So, cultivation in botanical gardens may be an important ex-situ conservation practice to guarantee protection to the remaining populations of this rare plant species.

The GeoCAT distribution maps ( Figs. 8–9 ) and details of Red List categories and criteria for all species of Astragalus sect. Trachycercis in the Iranian plateau ( Table 2 ) indicate that the conservation status of A. barnassari is also Least Concern (LC), however, A. shebarensis and A. pseudoshebarensis are evaluated as Vulnerable (VU). Both of A. barnasariformis and A. poliotrichus are known only from their type locations with no data on their populations, so they are categorized as DD (Data Deficient). Globally, the widespread A. testiculatus does not belong to any threatened category; however, it is a regionally vulnerable species because it is restricted to the west-central parts of Khorassan-Kopet Dagh Mountains in the Iranian plateau.

Figures

FIGURE 1. Scanned image of the isolectotype specimen of Astragalus durandianus kept in P (P03202941).

FIGURE 2. A specimen of Astragalus durandianus (Faghihnia & Zangooie 27565-FUMH) collected from Hezar-Masjed Mountains (NE Iran) with a relatively large-sized habit.

FIGURE 3. A–B) Astragalus durandianus in flowering stage (photos by: F. Memariani).

FIGURE 4. A–B) Astragalus durandianus in fruiting stage (photos by: M.R. Joharchi).

FIGURE 5. Some details of morphological characters in Astragalus durandianus. A) Relatively long terminal branches in fruiting stage (Rafeie & Zangooei 30651-FUMH); B) Floral bracts with black and white hairs (Joharchi & Memariani 46031-FUMH). Scale bars:A=10 mm; B=2 mm.

FIGURE 6. Some details of morphological characters in Astragalus durandianus. A–B) Fruits densely covered by a mixture of black and white hairs (A: Hojjat & Zangooie 32262-FUMH) or wholly by white hairs and on stipe by black hairs (B: Ayatollahi & Zangooie 14380-FUMH); C) Calyx in fruiting stage covered by black hairs (Rafeie & Zangooei 30651-FUMH); D) Seed. Scale bars: A–B=5 mm; C=2 mm; D=1 mm.

FIGURE 7. Distribution map of seven species of Astragalus sect. Trachycercis in the Iranian plateau based on confirmed identification of the herbarium specimens.

FIGURE 8. GeoCAT distribution map of Astragalus durandianus and estimation of Extent of Occurrence (EOO) and Area of Occupancy (AOO) based on IUCN Red List Criteria.