Phelipanche sevanensis Piwow., Ó. Sánchez & Moreno Mor., 2017

Piwowarczyk, Renata, Pedraja, Óscar Sánchez & Moral, Gonzalo Moreno, 2017, Phelipanche sevanensis (Orobanchaceae): a new species from the Caucasus, and nomenclatural notes on similar species, Phytotaxa 292 (2), pp. 231-242 : 232-238

Phelipanche sevanensis Piwow., Ó. Sánchez & Moreno Mor. , spec. nov. ( Figs. 1−3 )

Type: ― ARMENIA. Lesser Caucasus. Gegharkunik distr.: N. part of Lake Sevan, Tsovagyugh E., rocky slope, SW exposure, ca 1,945 m, 9 July 2015, R. Piwowarczyk s.n. (holotype KTC!; isotypes ERCB!, KRA!, herb. Ó. Sánchez Pedraja!) .

Description: ―Plant, (20–)30–33(–37) cm tall. Stem usually robust (with 2–5 smaller branches growing usually from the central part of the shoot) or, more rarely, simple, slender, (3–)4(–6) mm in diameter in the upper part, (4–)6–7(–12) mm in diameter in the middle part,(4–)8–10(–13) mm in diameter in the lower part, slightly bulbous at base; stem yellowish, rarely with a tinge of brown or blue (pale brown or brown when dry), slightly striate (clearly striate when dry); in the middle and upper part ± densely glandular-pubescent, with white glandular hairs 0.2–1.0 mm long, bearing orange glands. Basal leaves (10–)12–13(–15) mm × (4–)5–6(–7) mm, ovate-lanceolate (triangular) to lanceolate, glabrous abaxially or sparsely and shortly hairy, hairs ca 0.3 mm long. Upper leaves becoming sparser towards the upper part of the stem, more or less erect, (10–)11–12(–14) mm × (3.0–)3.5–4.0(–5.0) mm, narrowly lanceolate to lanceolate, pale yellow, pale brown, changing early to brown, densely glandular-pubescent with hairs 0.2–0.4 mm long. Inflorescence (4–)13–14(–23) × (2.0–)2.5(–3.0) cm, cylindrical, shorter than, rarely as long as, the remaining stem, usually many-flowered, ± dense. Bracts (10–)12–14(–17) × (3.8–)4.5–5.0(–6.0) mm triangular-lanceolate to lanceolate, usually shorter than the calyx, yellowish, changing early to brown in the apex, with ± dense white or pale yellow glandular hairs 0.2–0.5 mm long. Bracteoles (7–)10–11)(–12) × 0.8(1.0) mm, shorter than calyx, linearlanceolate, yellowish. Flowers erect. Calyx-teeth (7–)9–11(–13) mm long, at the widest point (1.0–)1.5–2.0(–2.5) mm wide, with 4 triangular teeth equalling the calyx tube, narrowly lanceolate with subulate to filiform apices, veined, (5–)6(–7) mm long, usually exceeding the calyx tube, but shorter than the corolla tube; densely glandular-hairy, hairs usually 0.2–0.3 mm long, white or pale yellow. Corolla (19–)21–23(–25) mm long, 4–5 mm in diameter in the central part, tubular-infundibuliform, clearly widened at the mouth, dorsal line slightly curved; base slightly inflated, constricted above stamen insertion, on the outer side ± densely (particularly at the upper lip) glandular-pubescent with white or pale yellow glandular hairs 0.1–0.3 mm; corolla whitish to white-violet, darker lobes blue to blue-violet with marked violet veins inside; upper lip bilobed, lobes ± erect, with subacute apex, pubescent; lower lip with three deflexed lobes (central lobe clearly larger than lateral lobes and elongated), large and broad ovate with acute apex, sometimes slightly emarginate, ciliate with short glandular hairs usually 0.3–0.4 mm long, with dense white hairs on the folds. Stamens obliquely inserted, adaxial ones 6–7 mm above the corolla base, abaxial ones 5–6 mm above the corolla base. Filaments whitish or whitish-blue, slightly widened at the base, 8–11 mm long, 0.5–0.7 mm wide, glabrous or with scarce white non-glandular hairs 0.5–0.8 mm long at the base, with dense short (0.1–0.2 mm long) white glandular hairs. Anthers (1.0–)1.5(–2.0) mm long, 1.0–1.3 wide, oblongoid, whitish or pale brown, apiculate; especially at the base, but often up to three-quarters of its length distinctly hairy with long hairy (1.0– 1.3 mm) along the suture. Ovary 5–7 mm × 3–4 mm, glabrous, whitish-blue; top opening after maturation. Style whitish-blue, 13–15 mm long, with very sparse (more abundant and dense on the upper part) short glandular hairs 0.1–0.2 mm long. Stigma quadrangular to discoid, slightly bilobed with two white lobes. Seeds oblongoid or ovoid; seed coat with fibrillar sculpture, reticulate with polygonal shallow cells ranging from ± isodiametric or irregular to tangentially elongated. Pollen tricolpate, spheroidal.

Distribution and habitat: ―The species is known exclusively from the type locality. Lake Sevan, located in the northern part of the Armenian volcanic highland in the Gegharkunik district, 60 km north-east of Yerevan, is the largest lake of the Transcaucasus Region and one of the largest freshwater high-mountain lakes of Eurasia. Phelipanche sevanensis grows in the rocky semi-arid mountain steppe on south to south-west exposed steep slopes surrounding the lake at 1,945 m a.s.l., dominated by the host species from the genus Heracleum ( Fig. 3 ). These stands are penetrated by ruderal species coming from the railway tracks and the road at the foot of the slopes. The ridges surrounding the lake consist of brown carbonate soil consisting of more than 30% stones; the bedrock is formed mainly by tufa and limestone.

Phenology: ―Flowering end of June to July, fruiting July to August.

Ecology: ―Parasitic on Heracleum trachyloma Fischer & Meyer (1835: 29) ( Apiaceae , subfamily Apioideae ) ( Fig. 3 ). This species is endemic to the Caucasus, occurring in Azerbaijan (Karabakh, Lenkoran, Nakhichevan), Armenia, and Turkey (Rize, Kars, Erzurum). Because of its wide distribution and the presence of numerous populations, it is listed as LC, but is collected for medicinal use ( Ali-Zade & Ekim 2014) and used as a pickled vegetable ( Hovsepyan et al. 2016). Frequently, several shoots of the parasite were observed on a single clump of the host ( Fig. 3 ).

Etymology: ―The epithet ‘ sevanensis ’ derives from the name of Lake Sevan, where the new species was discovered.

Conservation: ―The locality of Phelipanche sevanensis lies in the protected areas of Sevan National Park. The population is quite large and in good condition, including more than 200 shoots. There is no apparent and immediate threat, as its habitats are quite stable. A threat may arise, however, from disturbance of the habitat, resulting in erosion of the steep and rocky slopes, from overgrazing, the proximity of human settlements, railways, and main roads, and excessive tourism and trampling. In the last few years, a reduced water level, eutrophication, and human activity have undermined the ecological condition and biological diversity of Lake Sevan ( Babayan et al. 2006), and a similarly negative impact may also affect the terrestrial surroundings of the lake.

Discussion: ―Lake Sevan and its surroundings are situated at the junctions of the Transcaucasus and the Middle East Regions ( Babayan et al. 2006) and of the Caucasian and the Armeno-Iranian floristic provinces ( Takhtajan 1986). Hence, they include elements of various natural zones and are characterised by a high degree of richness of both flora and fauna. This area contains almost 1,600 vascular plant species (ca 50% of Armenian flora), 48 of which are included in the Red Data Book of Armenia and 6 of which are endemics ( Babayan et al. 2006). Phelipanche sevanensis should probably be considered a Caucasian endemic, considering that the host species, Heracleum trachyloma , is restricted to this region. However, the possibility that the species can also be found on other Heracleum species cannot be excluded.

Phelipanche sevanensis is, morphologically close to Phelipanche heldreichii (Reuter 1847: 8) Soják (1972: 130) [= P. hohenackeri (Reuter in Candolle 1847: 10) Soják (1972: 130)], described by Reuter from Konya (Central Anatolia, Turkey) based only on a single gathering of Heldreich 1845 n. 891 (Reuter in Candolle 1847: 8, Carlón et al. 2008). Later, it was reported as parasitic on Eryngium sp. (another very different Apiaceae of the subfamily Saniculoideae ) by Fedtschenko ( Beck 1930: 93). This species had previously been known only from some sites in Turkey and Armenia (Reuter in Candolle 1847: 8, Boissier, 1879: 498, Beck, 1890, Beck 1930, Novopokrovskij & Tzvelev 1958: 51, as O. coelestis f. persica [‘on Eryngium … Lake Sevan’], Gilli 1982: 10), Azerbaijan (Reuter in Candolle 1847: 8, us P. hohenackeri, Boissier, 1879: 499 , us P. ramosa var. mutelii [ P. hohenackeri ], Beck, 1890: 99 et 1930: 77, as O. mutelii var. typica [ P. hohenackeri ] et O. coelestis f. persica [‘ Eryngium sp. (s. Knapp)’], Rätzel et al. 2013), probably in Iran ( Beck 1890: 116 et Beck 1930: 93, Novopokrovskij & Tzvelev 1958: 59, as O. hohenackeri, Saeidi Mehrvarz et al. 2010: 110 , as O. schultzii Mutel , and other areas of the Caucasian Region ( Beck 1890, Beck 1930, Novopokrovskij & Tzvelev 1958: 59, as O. hohenackeri ). In the present study it has been confirmed in Armenia (see list below) in both the herbarium and the research field ( Fig. 5 ).

However, the newly-described species ( Figs. 1 , 2 ) differs very clearly from P. heldreichii ( Figs. 4 , 5 ) in morphology (a larger plant, inflorescence shorter than rest of the stem, any existing branches usually growing from the central part of the shoot, larger corolla with a different shape of tube, widened to the mouth, curved dorsal line and as well as the large and broad lobes, larger calyx tube, shorter calyx-teeth, different shape and size of bracts and upper scales), colouration of stem and inflorescence, host species, and flowering period, (2)3–4 weeks distance ( Table 1, Figs. 1 , 2 , 4 , 5 ).

Another related species, which could be confused with P. sevanensis is Orobanche coelestis (Reuter in Candolle 1847: 5) Beck (1890: 114) f. persica Beck (1890: 115) . This grows in Iraqi Kurdistan, in zones relatively close to the Caucasus. It can be clearly differentiated by morphological characteristics (indicated below) and parasitizes different hosts ( Achillea sp. ). However, we must note here that O. coelestis sensu Beck 1890 , Beck 1930, Novopokrovskij & Tzvelev 1958, Gilli 1982 et auct. pl. consists of a mixture of different species and this has caused a great deal of confusion in the interpretation of the original Reuter in Candolle (1847) species. Only the taxon which Beck called O. coelestis f. typica corresponds to the species of Reuter; the other taxa included by Beck in O. coelestis are morphologically very different from the species described by Reuter.

Phelipanche schultzii (Mutel 1835: 352) Pomel (1874: 107) has been repeatedly reported from the Near East, but actually inhabits both sides of the western Mediterranean Sea, extending eastwards to the Italian peninsula and Tunisia ( Sánchez Pedraja et al. 2016 +). P. schultzii also parasitises Apiaceae , including Distichoselinum sp. , Elaeoselinum sp. , Ferula sp. , Foeniculum sp. , and Thapsia sp. , but is not known from Eryngium sp. (host of P. heldreichii ) or Heracleum sp. (host of P. sevanensis ). P. schultzii is much more robust (up to 65 cm tall), with a simple or branched stem, inflorescences cylindrical, long, dense and many-flowered; calyx-teeth narrowly lanceolate with usually filiform apices, significantly longer than the tube; erecto-patent to patent, tubular-infundibiliform corolla, with a slightly curved dorsal line; anthers glabrous or sparsely hairy at the base. The probable origin of this confusion is that Beck (1890) and (1930) associated with P. schultzii (‘Gruppe der Trichocalyces ( O. schultzii , stricta, trichocalyx ’ [three conspecific taxa sensu Beck ( Carlón et al. 2008: 93)]) many Asian species with relatively long, dense and polyanthous inflorescences and, moreover, with calyx-teeth longer than the calyx tube.

To date, only a few unconfirmed reports of Heracleum as host species are known for Caucasian taxa within Orobanche alsatica aggr. Kirschleger (1836: 109), O. alsatica var. iranica Tzvelev in Komarov (1958: 105), and O. ingens ( Beck 1922: 38) Tzvelev (1990: 182) . This is the first report of Heracleum as host for any Phelipanche species.

Figures

FIGURE 1. Phelipanche sevanensis. A. Plant. B. Flower, side view. C. Flower, front view. D. Calyx and bracteoles. E. Bract. F.Leaf. G. Open corolla and androecium. H. Gynoecium. I. Stigma. J. Anther. Illustration by Jolanta Urbanik.

FIGURE 2. Inflorescence and general habit of Phelipanche sevanensis. Photos by Renata Piwowarczyk.

FIGURE 3. Host and habitat. A. Heracleum trachyloma – general habit of flowering host. B. Habitat with the dominant host species. C, D, E. Host with attached Phelipanche sevanensis. Photos by Renata Piwowarczyk.

FIGURE 4. Phelipanche heldreichii. A. Plant. B. Flower, side view. C. Flower, front view. D. Leaf. E. Bract. F. Open corolla and androecium. G. Calyx and bracteoles. H. Gynoecium. I. Stigma. J. Anther. Illustration by Jolanta Urbanik.

FIGURE 5. General habit and inflorescence (with acute and ovate lobes of corolla) of Phelipanche heldreichii (Armenia). Photos by Renata Piwowarczyk.