Phelipanche chionistrae (Orobanchaceae): a new holoparasitic species from Cyprus

Abstract Rätzel, S., R. Hand, C.S. Christodoulou & H. Uhlich (2021). Phelipanche chionistrae (Orobanchaceae): a new holoparasitic species from Cyprus. Candollea 76: 77–82. In English, English abstract. The new species Phelipanche chionistrae Rätzel, Hand, Christodoulou & Uhlich (Orobanchaceae) is described from Chionistra, the highest summit of the Troodos range in Cyprus. Morphological data strongly suggest affinities to the Phelipanche rosmarina complex, predominantly West Mediterranean taxa, and Phelipanche olbiensis (Coss.) Carlón et al. The new taxon can be distinguished by a combination of characters such as general colouration, structure of calyx and type of indumentum. Also, it has a different ecology being restricted to a high-montane serpentinophytic coenosis. Currently, only a few populations of the taxon, which is a parasite mainly on the Cypriot endemic Alyssum troodi Boiss. (and possibly other serpentinophilous species), are known. According to the IUCN Red List Categories and Criteria it should be assessed as “Near Threatened”. Received: May 20, 2020; Accepted: December 4, 2020; First published online: February 1, 2021


Introduction
The genus Phelipanche Pomel (= Orobanche sect. Trionychon Wallr.; Rätzel et al., 2017a) which has been accepted as a segregate genus from Orobanche L. by several authors (e.g. Schneeweiss, 2013;Rätzel et al., 2017a) comprises currently about 60 -72 species. Phelipanche shows centres of diversification in the West Mediterranean as well as in Asia Minor, Iran and Transcaucasia. Determination of its taxa can be challenging. Many species prove to be poor in diagnostic characters. On the other hand, various characters are extremely variable and difficult to compare, particularly in widespread taxa. Furthermore, many species can be found only very scattered in much fragmented distribution areas and appear irregularly. These facts complicate fieldwork considerably, especially in remote areas.
Recent studies have clarified the taxonomy of various poorly understood taxa, resulting in the description of several new species from the above-mentioned regions (e.g. Carlón et al., 2005Carlón et al., , 2008Rätzel et al., 2017a).
Several collections that could not be identified with any known species have been made recently in Cyprus, the largest island of the East Mediterranean, which is a biodiversity and endemism hotspot (e.g. Myers et al., 2000;Hadjisterkotis, 2008;Médail & Diadema, 2009). These collections represent a new species that is formally described here as Phelipanche chionistrae Rätzel, Hand, Christodoulou & Uhlich. Our study is based on the long-term fieldwork in Cyprus by CSC and RH and extensive field and herbarium studies by SR and HU of the vast majority of Euro-Mediterranean Phelipanche taxa, some of which currently have no valid combination under that genus and are therefore referred to here by their Orobanche names. Materials preserved in the following herbaria have been studied: B, COI, CYP, G, JE, K, MB, NMNH, P, W, WU and the private herbarium of Georgios Hadjikyriakou.
Etymology. -The epithet chionistrae refers to the Mt. Chionistra, colloquially also known as Mt. Olympos, reaching 1.952 m above sea level and forming the highest elevation of both the Troodos range and the island of Cyprus.
Distribution and habitat. -Phelipanche chionistrae seems to be endemic to the highest altitudes of Mt. Chionistra (Fig. 3). Meikle (1985) does not cite any material from the higher altitudes of Mt. Chionistra under the name Orobanche ramosa s.l. possibly because of its relative rareness. The summit consists of Upper Cretaceous, more or less serpentinized and tectonized harzburgites which belong to the Troodos ophiolite complex (GSD, 1995). The vegetation of the peak is generally dominated by very open stands of Pinus nigra subsp. pallasiana (D. Don) Holmboe. Phelipanche chionistrae has been found on large openings with sparse vegetation cover, often less than 10 %. The terrain is extremely rocky complicating the determination of hosts of the new taxon, which sometimes grows in clefts of bare serpentine rocks at considerable distance from any other vascular plant. Hitherto, it has only been found at an altitude of 1500 -1900 m.
Phenology. -Flowering individuals of P. chionistrae have been found from May to June.
Conservation status. -Phelipanche chionistrae was first observed in 2009 and since then several small populations (1 -20 plants) have been located at eight places on the higher parts of Mt. Chionistra in an area of 10 km2, all found within the Troodos National Forest Park, which is also a Natura 2000 site, with controlled human activities. However, climate change is a potential threat for this high-altitude species. Considering the protected status of its distribution area, the low level of threat, the small known population (< 1000) and the restricted Area of Occupancy (< 10 km2) (IUCN, 2012) as well as incalculable habitat changes as a result of climate change (e.g., Giannakopoulos et al., 2010;Hadjinicolaou et al., 2011), the species could be preliminary assessed as "Near threatened" [NT]. Further surveys are needed in the higher peaks of central Troodos such as neighbouring Madari and Papoutsa peaks to better understand its distribution.  Table 1. Several diagnostic characters are lost in herbarium specimens of Orobanchaceae and they need to be studied in fresh material. This is the case for example of the indumentum in P. olbiensis which provides a good diagnostic character (Table 1). Its flowering shoots are densely covered with short glandular hairs with relatively large yellow-hyaline heads; longer glandular hairs are scarce or lacking. Depending on the light conditions, plants look matt velvety or glittering (Fig. 4A). As it contrasts with the colour of the stem and bracts this character can be clearly seen. All other taxa have a rather silky indumentum (Fig. 4B) which is caused by a mixture of short and long glandular hairs with smaller, inconspicuous glandular head that cover stem and bracts. Phelipanche chionistrae also differs by its preference for higher altitudes. With the exception of P. sinaica (Beck) Rätzel & Uhlich which however shows a differing host spectrum, the other taxa prefer lower altitudes (sea-level up to c. 650 m). Phelipanche sinaica differs from P. chionistrae by its permanently compact inflorescences which are relatively rich in flowers (c. (8-)14-28(-30) vs. c. 3-10(-12)) and by its paler to dull violet corollae. Phelipanche sinaica parasitizes Lactuca viminea (L.) J. Presl & C. Presl and it is known to occur in Azerbaijan, Egypt and Iran (Rätzel et al., 2017b). Apart from P. nowackiana (Markgr.) Soják, a NE Mediterranean species that also parasitizes perennial taxa of Alyssum s.l., Phelipanche chionistrae is the second species known to be a strict serpentinophyte.