Dionysia × kowsarana Zeraatkar & Khajoei Nasab,

Zeraatkar, Amin & Nasab, Farzaneh Khajoei, 2022, A new natural hybrid in Dionysia (Primulaceae), Phytotaxa 559 (1), pp. 64-72 : 64-71

Dionysia × kowsarana Zeraatkar & Khajoei Nasab, hybr. nov. ( Figs. 1–4 ).

( D. bryoides Boiss. × Dionysia diapensiifolia Boiss. )

Diagnostic characters:—The hybrid Dionysia × kowsarana is superficially similar to D. bryoides ; however, it is intermediate between their parents in terms of macro and micro-morphological characters ( Table 1 ).

Type:— IRAN. Fars province, Marvdasht, Ramjerd area, Zarghanak village , southern slope of Mount Ayub , 52.639186° N; 30.025586° E, 1655 m, 10 March 2019, A. Zeraatkar 7042 (holotype: D!) .

Description:—Dense cushions, aromatic, non-farinose, green, with stems in the upper part covered with marcescent leaves. No noticeable difference between early and late leaves. Stems shortly branched, with closely imbricating marcescent leaves along the branches, densely with glandular hairs, becoming reddish brown, 5–15 cm long; dead leaves of previous years present. Leaves green, usually entire, rarely dentate, elliptic to spathulate, subspathulate, obtuse to subobtuse or acute, flat, 2–5.5 × 0.6–2 mm; upper and lower lamina surfaces densely set with medium and rarely long and short stalked glandular hairs, (0.1–0.15) 0.2–0.4 (0.5–0.6) mm long. Bracts 1–2, like the leaves, but shorter and narrower, 2–3.5 × 1–1.5 mm, entire, oblong-linear or lanceolate, acute, glands like leaves. Calyx 2.5–3.5 mm long, split to 4/5, 5/6, or the base in oblong-linear acute erect lobes, similar to the bracts, pubescence like that of leaves. Flowers solitary, sessile. Corolla violet or pink with a yellow eye, moderately covered by most stalked glandular hairs, (0.2) 0.4–0.6 mm long; tube 16–18 mm long in long-styled flowers, 14–17 mm long in short-styled flowers; limb 7–9 (10) mm broad, with emarginate or minutely emarginate lobes. Style of short-styled flowers 7–9 mm long, that of long-styled flowers not exserted, up to 12 mm long. Stamens ca. 1 mm long, inserted in the throat or in the middle of the corolla tube. Ovary with 4 to 6 ovules. Capsules usually with seeds that lack embryos, rarely with viable seeds; seeds dark brown, oblong to ovoid or elliptic 0.7–1.3 × 0.3–0.5 mm.

Etymology:—The epithet of the hybrid is dedicated to Dr. Sayyed Ahang Kowsar, Professor of Fars Agricultural and Natural Resources Research Center, for his remarkable efforts in alleviating water scarcity.

Phenology:—At Mount Ayub, D. diapensiifolia starts to flower at the beginning of February and continues, depending on weather conditions, until the end of April or even until the beginning of May. Dionysia × kowsarana starts to flower almost simultaneously with/or one week earlier than D. diapensiifolia and its flowering continues until the beginning of April. D. bryoides starts to flower about two weeks earlier than D. diapensiifolia and continues until mid-April.

Reproduction:—Production of viable seeds in Dionysia × kowsariana is rare. All capsules collected in 2019 generally contain non-embryonic seeds and rarely viable seeds. Additional investigations are necessary to further clarify the genetic composition of hybrid plants and more hybrid zones.

Population size and conservation status:— So far this new hybrid is known only from the type locality, in which Dionysia bryoides and D. diapensiifolia coexist. These species also are occurring sympatrically and occupy a similar habitat in Mount Sabzpushan, near Shiraz. The habitats were studied at the time of species fruiting and because the first indicator to find hybrid plants in the genus was flowers, we were unable to assess potential hybridization events in the habitat. Dionysia × kowsarana individuals were few and 1–2 plants were observed per hybrid zone (2–3 m 2). Mount Ayub is one of the largest habitats of D. diapensiifolia and D. bryoides in southwestern Iran ( Zeraatkar et al. 2022) and the species grow very abundantly in the mountain. Despite overlap of ranges and significant overlap of flowering periods, only a few hybrid zones are known. The habitat of species is close to human habitation and is threatened by the trampling of livestock and ecotourists. Following the IUCN Red List Criteria and Categories ( IUCN 2019), D. × kowsarana should be considered as “critically endangered” according to criterion B2, its extent of occurrence is <10 km 2 and to according to criterion D, the number of its mature is <50 individuals.

Distribution and ecology:—The majority of Dionysia species have highly restricted geographic ranges ( Lidén 2007). But here hybridization occurs between two species, namely D. bryoides and D. diapensiifolia with a relatively wide geographical distribution. D. diapensiifolia is distributed in the provinces of Fars, Kohgiluyeh and Boyer-Ahmad, and open Persian oak ( Quercus brantii Lind. ) as well as Prunus scoparia (Spach) C.K. Schneid woodlands, are the main habitats of this species. Another species, D. bryoides , has a wider distribution in Iran and has been reported from some highlands in the phytogeographical provinces of Central Iran, Kurdo-Zagrosian, Fars and Kerman, and Nubo-Sindian. It grows in the mountains provinces of Isfahan, Chaharmahal and Bakhtiari, Fars, Kohgiluyeh and BoyerAhmad and Bushehr ( Zeraatkar et al. 2022).

Mount Ayub is one of the numerous solitary mountains of the Zagros Range in southwestern Iran, where it was botanically explored by Karl Georg Theodor Kotschy in 1842 ( Edmondson & Lack 2006). The southern and northern slopes of mountain differ in vegetation composition and orographic structure. The northern slopes are made up of alluvial fans, marl hills, rocky slopes, and also vertical limestone cliffs, where Prunus associations such as P. scopcria (Spach) S. K.Schneider , P. elaeagnifolia (Spach) Fritsch and cushions grow. In contrast, the southern slopes consisted of overhangs, cliff walls, steep and vertical niches and mainly obligate chasmophyte taxa ( Fig. 4a .). There are different types of microhabitats on the southern slopes and numerous endemic species are present there such as Silene persepolitana Melzh. , Dionysia spp. , Telephium eriglaucum Williams , Salvia persepolitana Boiss. , Scrophularia longiflora Benth. , Paracaryum modestum Boiss. & Hausskn. , Astragalus penetratus Maassoumi , Campanula persepolitana Kotschy ex Boiss. , Acantholimon schirazianum Boiss. , Pterocephalus lignosus Freyn & Bornm. , Hyoscyamus bornmulleri Khatamsaz , H. tenuicaulis Schönb. -Tem., and Satureja bachtiarica Bunge.

The cliffs of the mountain are certainly also a unique habitat for Dionysia species. In Mount Ayub, D. diapensiifolia is a semi sciophyte species and inhabits below overhangs and semi-shaded limestone cliffs crevices on the southern slopes while D. bryoides generally prefers the sunny and semi-shaded limestone cliffs crevices of the southern and northern slopes ( Figs. 4 , 5 ). Therefore, in mountainous region, the desirable habitats of D. bryoides are much more than D. diapensiifolia , and as a result, there are far more individuals of D. bryoides than D. diapensiifolia . The hybrid zones are always in a very narrow ecotonal region between the parental preferred habitats, where their suitable habitat are intermediate lighting conditions compared to the parental species ( Fig. 4 ).

The geographical distributions of the two parental species and hybrid plants entirely would overlap. It seems likely that our hybrid zones follow a mosaic pattern where hybrid plants grow along distinct microhabitats in areas of sympatry among the parental species ( Fig. 4 ). This hybrid species distribution model is common in herbaceous perennial species ( Zheng et al. 2021).

Morphological variation of hybrid plants:—The morphological comparison among Dionysia × kowsarana and its parents is shown in Table 1 . The hybrid is morphologically intermediate between the parent species. However, our morphometric data and field observations revealed significant variation in the morphological characteristics of hybrid plants.

Despite the leaves are rarely dentate in the hybrid, the number of dentate leaves is significantly more abundant in the specimen with the voucher number D-7042. The leaves size of the specimen with the voucher number D-7043 is significantly larger than the leaves of the other specimens, in addition, the leaves apex of the specimen with the voucher number D-7043 are acute and subacute (rarely obtuse and subobtuse) while they are obtuse and subobtuse in the specimens with the voucher number D-7042, D-7044, D-7045, which is a characteristic feature of D. bryoides ( Fig. 3 a–d ). It is necessary to note that leaves are marginally variable in D. diapensiifolia , however, they are usually dentate in Ayub mount ( Fig. 2b ). Floral morphology varies within the hybrid. Corolla tube length of the specimen with the voucher number D-7043 is long in comparison with other specimens (17–18 vs. 14–16 mm). Moreover, corolla lobes show significant variation among the hybrid plants. Like D. diapensiifolia , the corolla lobes of the specimen with the voucher number D-7043 are minutely emarginate while those of the specimens with the voucher number D-7042, D-7044, D-7045 are emarginate similar to D. bryoides ( Figs. 1 , 2 a,c,e ). In contrast, the diameter of corolla lobes in the specimen with the voucher number D-7043 are close to D. bryoides whereas those of the specimens with the voucher number D-7042, D-7044, D-7045 are large and close to D. diapensiifolia ( Fig. 1 ). The trait variations are probably due to various parentage of the hybrid plants and also phenomena of the swarm, introgression and production backcrosses.

Dionysia × kowsarana is the second natural hybrid in the genus Dionysia . The first confirmed hybrid was reported by Grey-Wilson (1974) from Dena Mountain, where the distribution range D. bryoides and D. termeana Wendelbo (1970) is overlapped. The species occupy distinct elevations of Dena Mountain. In the mount, D. bryoides lies at altitudes between 1900–3200 m a.s.l while D. termeana is located in the alpine zone ranging from 3000 to 3900 (4000) m a.s.l. The hybrid zone form in the altitude range between 3000 to 3200 m a.s.l. where the species come into geographical contact.

On the other hand In the mount, our observation shows the widespread species of the genus, Dionysia revoluta Boiss. ( Younesi et al. 2017) , grows sympatrically with D. diapensiifolia (in Mount Sabzpushan and Mount Shahrak) and D. bryoides (Mount Sabzpushan, Mount Nil and Saran) . In addition, D. diapensiifolia and D. viva Lidén & Zetterl. co-occur in the same habitat (in Mount Dehbid). Grey-Wilson (1989) stated natural hybridization is rarely occurred in the genus due to ecological and geographic isolation. However, no hybrid plant was observed between these species and concerning bloom simultaneously, pre-zygotic barriers can contribute to species delimitation. Interestingly, the result suggests only Dionysia species that are placed in the same section potentially would seem to make a hybrid. These findings provide some evidence that the section classification designated by Lidén (2007) is natural and welldefined.

Additional specimens examined. Dionysia bryoides Boiss. : IRAN. Fars province, Marvdasht, Ramjerd area, Zarghanak village , southern slope of Mount Ayub , 52.639229°N; 30.025315° E, 1645–2000 m, 10 March 2019, A. Zeraatkar 7046 (D!). Marvdasht, Ramjerd area , between Chamani and Boraki villages, northern slope of Mount Ayub , 52.657214° N; 30.035822° E, 2100 m, 19 March 2018, A. Zeraatkar 7047 (D!). Marvdasht, Ramjerd area , ca. 1.5 km Chamani village from Kushkak, northern slope of Mount Ayub , 52.639436° N; 30.054711° E, 1810 m, 25 May 2018, A. Zeraatkar 7048 (D!). Marvdasht, Saran, 52.087300° N; 30.393840° E, 2050–2100 m, 13 March 2015, A. Zeraatkar 7050 (D!). South Shiraz , Kushk Bidak, northern slope of Mount Sabzpushan , 52.542224° N; 29.413058° E, 1982 m, 10 May 2021, A. Zeraatkar 7049 (D!). Kohgiluyeh and Boyer-Ahmad Province . Mount Nil , 30.864083, 50.896952, 2600–2800 m S. Rokhideh s.n. (Yasuj University herbarium).— D. diapensiifolia Boiss. : IRAN. Fars province: Marvdasht, Ramjerd area , Zarghanak village , southern slope of Mount Ayub , 52.639229°N; 30.025315° E, 1645–2000 m, 10 March 2019, A. Zeraatkar 7051 (TARI, D!). South Shiraz , Kushk Bidak, northern slope of Mount Sabzpushan , 52.554534° N; 29.414276° E, 1745–1800 m, 10 May 2021, A. Zeraatkar 7052 (D!). Arsanjan, Valiabad, Mount Dehbid , 53.2061 °N; 29.7958° E, 1750–1900 m, 8 April 2020, A. Zeraatkar 7053 (D!). Marvdasht, Abarj area , northern slope of Mount Shahrak , 52.528513° N; 30.182284° E, 1950–2000 m, 19 March 2013, A. Zeraatkar 7054 (D!).— D. × kowsarana Zeraatkar & Khajoei Nasab: IRAN. Fars province: Marvdasht, Ramjerd area , Zarghanak village , southern slope of Mount Ayub , 52.643500° N; 30.025751° E, 1893 m, 27 March 2019, A. Zeraatkar 7044 (D!; paratypes). Marvdasht, Ramjerd area , Zarghanak village , southern slope of Mount Ayub , 52.643500° N; 30.025751° E, 1893 m, 27 March 2019, A. Zeraatkar 7045 (D!; paratypes). Marvdasht, Ramjerd area , Zarghanak village , southern slope of Mount Ayub , 52.639229°N; 30.025315° E, 1645 m, 10 March 2019, A. Zeraatkar 7043 (D!; paratypes). D. viva Lidén & Zetterl : IRAN. Fars province: Arsanjan, Valiabad, Mount Dehbid , 53.2061°N; 29.7958° E, 1750–1900 m, 8 April 2020, A. Zeraatkar 7021 (D!). D. revoluta Boiss. IRAN. Fars province: Marvdasht, Abarj area , northern slope of Mount Shahrak , 52.528513° N; 30.182284° E, 1950–2000 m, 19 March 2013, A. Zeraatkar 7055 (D!). South Shiraz , Kushk Bidak, northern slope of Mount Sabzpushan , 52.554534° N; 29.414276° E, 1745–1800 m, 10 May 2021, A. Zeraatkar 7056 (D!). Marvdasht, Saran, 52.087300° N; 30.393840° E, 2050–2100 m, 13 March 2015, A. Zeraatkar 7057 (D!). Kohgiluyeh and Boyer-Ahmad Province . Mount Nil , 30.864083, 50.896952, 2600–2800 m S. Rokhideh s.n. (Yasuj University herbarium!)

Figures

FIGURE 1. Morphological variation within flowers of Dionysia × kowsarana in different hybrid zones.

FIGURE 2. Flowers in D. diapensiifolia (a), Dionysia × kowsarana (c), D. bryoides (e). Leaves in D. diapensiifolia (b), Dionysia × kowsarana (d), D. bryoides (f).

FIGURE 3. Leaves. a, Dionysia × kowsarana: D-7045 (scale bar= 1 mm) b, D-7042 (scale bar= 1 mm) c, D-7043 (scale bar= 2 mm) d, D. bryoides (scale bar= 1 mm) e & f, D. diapensiifolia (scale bar= 2 mm). Marginal hairs of leaf: g, D. diapensiifolia h, hybrid i, D. bryoides (scale bar= 0.5 mm).

FIGURE 4. Habitat of Dionysia × kowsarana and its parents. Yellow arrows: D. diapensiifolia, red: D. bryoides, white: Dionysia × kowsarana.

FIGURE 5. Habitat of Dionysia diapensiifolia (a), and D. bryoides (b), D. diapensiifolia and D. bryoides co-occur in the same habitat (c).