Stachys siirtensis Ö.Güner & Akçiçek, 2021

Güner, Özal, Akçiçek, Ekrem & Dirmenci, Tuncay, 2021, A new Stachys species from Turkey: Stachys siirtensis (Lamiaceae), Phytotaxa 516 (3), pp. 252-262 : 253-258

Stachys siirtensis Ö.Güner & Akçiçek sp. nov. (Figs. 1,2)

Diagnosis: — Stachys siirtensis differs from S. ballotiformis mainly by flowering stems with glabrous to sparsely and retrorsely pubescence, longer calyx (8–10 mm long) and corolla (13–15 mm long) and separates from S. kurdica by stalked glandular flowering stems, congested verticillaster, having pilose and sessile glands on calyx, and oblong-obovoid nutlets.

Types: — Turkey, Siirt, Eruh to Şırnak, close to the Şırnak border, Botan Valley , rocky slopes, 700–750 m, 11.06.2013, Ö . Güner 2333, Akçiçek, Dirmenci (holotype GAZI, isotypes ISTE, ANK, HUB) .

Description:— Suffrutescent perennial herbs. Flowering stems numerous, 25–40 cm long, fragile, erect, simple or branched; usually glabrous to sparsely and retrorsely pubescent with sessile glands, sometimes stalked glandular hairs below. Cauline leaves lanceolate to linear-lanceolate, 0.8–3.1 × 0.4–0.8 cm, weakly serrate-dentate to subentire, apex acute to obtuse, attenuate at base, sparsely pubescent, petiole 0.2–2 cm long. Floral leaves similar to cauline leaves but smaller, 0.8–2.5 × 0.1–0.3, entire sometimes weakly serrate-dentate, apex acute, sparsely pubescent and margin hairy, petiole 0.1–0.2 cm long, shorter than verticillaster and as long as calyx. Verticillasters densely congest, rarely one remote, 6–10 flowered. Bracteoles few, setaceous to herbaceous, 0.5–2(–3) mm long, pilose, shorter than ½ calyx. Pedicels 0.5–1.5 mm long. Calyx ± regular, infundibular, 8–10 mm long, sparsely or densely pilose with sessile glands; teeth ± regular, 2.5–4 mm long, triangular-lanceolate. Corolla cream yelow, 13–15 mm long, tube exceeding the calyx, pilose outside; limb bilabiate, upper lip 4 mm long; the lower lip 3-lobed, middle lobe larger than 2 lateral lobes, 6–7 mm long. Style not exceeding the upper lip, 8 mm long, glabrous, apex equally bifid into subulate stigmas. Stamens 4, within corolla tube, filament stalked and with sessile glands, anthers dithecous, thecae divaricate. Nutlets oblongobovoid, 2–2.5 × 0.5 mm, slightly winged near base, reticulate on surface, brown to dark brown.

Distribution and ecology:— Stachys siirtensis only grows on rock cracks, mouth of limestone caves and limestone at an elevations from 600–800 m in surroundings of the Botan river of Siirt province, Turkey ( Figs 5–6 ). It is an Irano- Turanian element. It shares habitat with the herbs Campanula flaccidula Vatke (1874: 38) , Campanula reuteriana Boissier & Balansa (1856: 3) and Scutellaria orientalis Linnaeus (1753: 598) , and the tree Quercus infectoria Olivier (1801: 1) and Paliurus spina-christi Miller (1768: 8) .

Conservation status:— Stachys siirtensis has only a single known population in surroundings of the Botan river in Siirt. The habitat is close to the main road of Siirt-Şırnak provinces. The species is endemic to Turkey. We noted less than 250 mature individuals. We also observed grazing effects in the area because domestic animals such as sheep and cattle have been raised in the surrounding villages. Therefore, The new species is assessed as Endangered (EN) according to criterion D of the IUCN Red List Criteria ( IUCN 2019). Nevertheless, more accurate investigation in field on the distribution range, the threats, the number of individuals, and the population trend is needed for a consistent assessment of the conservation status of S. siirtensis . In fact, the detected grazing in the area could possibly lead to a decline and so the species should be assessed as Critically Endangered (CR) according to IUCN (2019) criteria B and C, as many other species with so a small distribution range (e.g. García 2003; Wagensommer et al. 2014, 2017; Ravikanth et al. 2018; Wagensommer & Venanzoni 2021), even if other species with small range were assessed as not threatened, when no decline was observed or projected ( Perrino et al. 2018).

Etymology and vernaculare name:— The epithet of the new species is derived from the name Siirt province where the type specimen was collected. The name of S. siirtensis is proposed as “Botan kayaçayı” in Turkish, according to the guidelines of Menemen et al. (2016).

Phenology:— This new species flowers in May and fruits in mid-May and June.

Taxonomic relationships:— Section Fragilicaulis is divided into two subsection i.e. Fragiles and Multibracteolatae. The subsect. Fragiles species are only distributed in Mediterranean region, while species in the subsect. Multibracteolatae grow in southeast of Turkey, eastern Black Sea region of Turkey and east of Central Anatolia ( Bhattacharjee 1974). At first glance, three species ( S. kurdica Boissier & Hohenacker (1844: 31) , S. mardinensis (Post) Mill (1980: 38) and S. viscosa Montbret & Aucher ex Bentham (1836: 49)) are clearly distinguished within the subsect. Multibracteolatae. These species form a complex with the taxa which they similar to each other. Stachys kurdica complex ( S. ballotiformis Vatke (1875: 33) and S. benthamina Boissier (1879: 734)) is characterized by having inconspicuous bracteoles, usually lanceolate and small cauline leaves, slender and long stems. Stachys mardinensis complex ( S. megalodonta Haussknacker & Bornm. ex Davis (1951: 46) , S. baytopiorum Kit Tan & Yildiz (1988: 450) and S. glechomifolia Nábelek (1926: 61)) is described by having forming clump, conspicuous bracteoles and dense cauline leaves. Stachys viscosa complex ( S. laetivirens Kotscky & Boisser ex Rechinger (1941: 71) , S. subnuda Montbret & Aucher ex Bentham (1836: 50) and S. tundjeliensis Kit Tan & Sorger 1987: 155 )) is distinguished by having conspicuous bracteoles, long stem, more flowers in verticillasters and campanulate calyx. In addition, Stachys viscosa complex is geographically distinct from the other two complexes ( Fig. 3 ).

Stachys siirtensis belongs to Stachys kurdica complex within the subsect. Multibracteolatae. The species is symbolized by having congested verticillasters and can clearly be distinguished from these three species. The new species is morphologically similar to S. kurdica and S. ballotiformis which belong to S. section Fragilicaulis ( Fig. 4 ). These species are suffrutescent, with woody rootstock, and grow on rocky crevices. Their flowering stems are fragile at the base. Verticillasters that are densely congest are the most distinctive character of S. siirtensis ( Fig 2 .). Some characters of S. siirtensis are used to distinguish between S. ballotiformis and S. kurdica . Stachys siirtensis differs from S. ballotiformis in flowering stems with glabrous to sparsely and retrorsely pubescent, long calyx (8–10 mm long) and corolla (13–15 mm long) and from S. kurdica in flowering stems with stalked glandular hairs, congest verticillasters, calyx with pilose and sessile glands, and oblong-obovoid nutlets ( Table 1).

Botan Valley, that is placed in Siirt Province in Turkey, has been declared as National Park by the decree of the Presidency of the Republic of Turkey due to its high biodiversity and anthropological features on 15 August 2019. This new species grows in the part of Botan Valley that is close to Eruh district. The identification of S. siirtensis , as a new endemic species, will contribute to the knowledge of the biodiversity of Botan Valley and probably encourage the other botanists to examine the area ( Fig. 6 ).

Figures

FIGURE 2. Verticillasters of Stachys siirtensis A. Natural habitat, B. Herbarium specimen

FIGURE 3. Distribution map of Stachys siirtensis and the complex of three Stachys (Annotation: In markers of complexes of S. viscosa and S. mardinensis on the map, two types (round and triangle) of the sign were used in order to show only the distribution of these complexes)

FIGURE 4. Habits of Stachys ballotiformis (photograph by. M. Fırat) (A) and S. kurdica (photograph by. Ö. Güner) (B).

FIGURE 5. Habitat of Stachys siirtensis in Siirt province, Turkey.

FIGURE 6. A view from a part of Botan Valley National Park in Siirt Province (Photograph by Serdar Uzun, NTV)