ACTA BOT. CROAT. 77 (1), 2018 105 Acta Bot. Croat. 77 (1), 105–108, 2018 CODEN: ABCRA 25 DOI: 10.1515/botcro-2017-0021 ISSN 0365-0588 eISSN 1847-8476 Short communication Rare plants of threatened habitats – the Croatian case of Corrigiola litoralis L. (Caryophyllaceae) Nina Vuković1, Vedran Šegota2*, Antun Alegro1, Zorana Sedlar3 1 University of Zagreb, Faculty of Science, Department of Biology, Division of Botany, Marulićev trg 20/II, HR-10000 Zagreb 2 University of Zagreb, Faculty of Science, Department of Biology, Division of Botany, Herbarium Croaticum (ZA), Marulićev trg 20/II, HR-10000 Zagreb 3 Croatian Natural History Museum, Department of Botany, Demetrova 1, HR-10000 Zagreb Abstract – Corrigiola litoralis is the only member of the genus in the Croatian flora. Most available data are more than 50 years old, and include only four localities in Croatia, exclusively in the islands of the Mediterranean region. During a floristic survey of the island of Molat (Northern Dalmatia) we recorded a small population in Zapuntelsko polje, in a damp, shallow depression, seasonally occurring as a temporary pond. Comparison with the existing literature shows that C. litoralis often occurs in Mediterranean temporary ponds and similar globally important and threatened habi- tats. We strongly believe that careful studies of populations of C. litoralis and other species with similar ecologies are necessary in order to preserve these habitats and therefore propose actions to achieve this goal. Keywords: endangered habitats, IUCN, Mediterranean temporary ponds, Molat * Corresponding author, e-mail: vedran.segota@biol.pmf.hr Introduction According to Flora Europaea, the genus Corrigiola is rep- resented in Europe by two species: C. litoralis L. (with two subspecies, C. litoralis L. ssp. litoralis and C. litoralis L. ssp. telephiifolia (Pourr.) Briq.), and C. imbricata Lapeyr (Walters and Akeroyd 1993). According to the Croatian checklist, C. litoralis, and a typical subspecies (C. litoralis L. ssp. litoralis) have so far been registered in Croatia (Nikolić 2016). C. litoralis is a short, prostrate annual, with slender stem, very small flowers (2 mm diameter when expanded), and al- ternate leaves (unlike most Caryophyllaceae) (Coker 1962, Walters and Akeroyd 1993). It grows on periodically wet, sandy or gravel ground, in damp, open environments; often in sites along rivers, lakes and ponds subject to fluctuating water levels and with seasonally exposed shores (Walters and Akeroyd 1993, McHugh 2007, Hamston 2010). Native distri- bution of C. litoralis is Mediterranean-Atlantic, with occur- rences in North, East and South Africa (Coker 1962, Rankou et al. 2015). The introduced range includes Australia (Rank- ou et al. 2015) and probably America (Coker 1962, Rankou et al. 2015). In the Mediterranean parts of South and West Europe, the species is very widespread and common (Rank- ou et al. 2015). According to the IUCN, Corrigiola litoralis is globally considered a species of least concern (LC), for the overall trend of the population appears stable, although it is very rare and threatened locally, for example in England, at the northern fringe of its distribution (Hamston 2010). In Croatia, only four localities were known prior to this study, and moreover, only one historical record was con- firmed during the 21st century (Visiani 1852, Lusina 1938, Trinajstić 1979, Škunca et al. 2008) (Fig. 1). The first known records date from the middle of the 19th century, when Vi- siani (1852) noted this species for the islands Krk (north- ern Adriatic) and Korčula (southern Adriatic). The record from Krk was confirmed later by Schlosser (1856) (ZA col- lection), Tommasini (1875) and Trinajstić (1965), while a finding from Korčula was cited once without confirma- tion (Trinajstić 1985), and never mentioned in the litera- ture since. As much as 86 years after the first records, a new record from Lusina (1938) was published, of a finding of C. litoralis on the island of Unije (northern Adriatic). This record was confirmed by the same author almost two de- cades later (Lusina 1956), and cited in recent times but with- out confirmation (Wallnöfer 2008). Finally, the species was found by Trinajstić (1979) on the island of Lastovo (south- ern Adriatic), and confirmed in recent times during a floris- tic study of the Lastovsko otočje Nature Park (Škunca et al. VUKOVIĆ N., ŠEGOTA V., ALEGRO A., SEDLAR Z. 106 ACTA BOT. CROAT. 77 (1), 2018 2008). The data on C. litoralis on Krk and Unije published by Rottensteiner (2014), refer to previously mentioned histori- cal data, and were not confirmed in recent times. Literature data show that Corrigiola litoralis often occurs in Croatia on sandy soil, regularly around ponds or lakes, exclusively in the Mediterranean part of the country (Vi- siani 1852, Hayek 1924–1927, Lusina 1938, 1956, Trinajstić 1965, Topić and Vukelić 2009, Rottensteiner 2014). Trinajstić (1965, 2008) recorded it in Ponikve (Krk) along the shores of a temporary pond (dry at the time) within the association Plantagini intermediae-Crypsidetum schoenoidis Trinajstić 1965, a community associated with Mediterranean tempo- rary ponds (Topić and Vukelić 2009). Although C. litoralis is extremely rare in Croatia, it was never estimated according to the IUCN criteria. Materials and methods In October 2015, several fieldtrips were undertaken with- in a floristic study of the island of Molat in the Zadar archi- pelago (Northern Dalmatia). The north-western part of the island, in the area of Zapuntelsko polje, was researched on 25th October. GPS coordinates (according to WGS84) were recorded and lists of vascular plants were prepared for four selected sites in that area, while some plant taxa were photo- graphed. Specimens of Corrigiola litoralis were collected and stored in Herbarium Croaticum (ZA). Shortly after the fieldtrip, the Flora Croatica Database (Nikolić 2016) was searched for C. litoralis, and all the related literature was closely examined. Both Herbarium Croaticum (ZA) and Herbarium Ivo and Marija Horvat (ZAHO) were searched for C. litoralis (Appendix 1). Results and discussion Corrigiola litoralis was found in the Zapuntelsko polje (Fig. 2), at coordinates 44°14'59"N, 14°48'28"E. It was re- corded in a shallow depression in the north-western part of the field, dry at the time of our visit, but occasionally exist- ing as a pond (Fig. 3). The water regime varies from year to year, depending on the rainfall, but the pond seasonally dries out, and the drought period usually extends from late spring, till late autumn. The pond is not particularly maintained by the local inhabitants; nevertheless the nearby area is occa- sionally used for pasturing (mainly by sheep). Although the area was dry at the time, the presence of some plants com- monly found in moist habitats, such as Agrostis stolonifera L., Poa trivialis L. ssp. sylvicola (Guss.) H. Lindb., Ranunculus sardous Crantz, Oenanthe pimpinelloides L., Carex divulsa Stokes and others, clearly indicates the importance of water in this particular site. Only a few plants of Corrigiola litoralis were found, grow- ing on patches of bare soil, in periodically flooded parts of the field (Fig. 3). All individuals were vigorous and gener- ally in a good state, showing no signs of herbivory or patho- gens, and flowering at the time (Fig. 4). The species was re- corded in a typical microhabitat; it prefers open sites, with sparse vegetation preferably not higher than 2–4 cm, in areas where occasional flooding and moderate trampling reduce the competition from more robust plants (Coker 1962). In addition, the same microhabitat in Zapuntelsko polje was occupied by some peculiar and rare ephemeral liverworts (Fossombronia echinata Macvicar, Fossombronia caespitifor- mis De Not. ex Rabenh. ssp. multispira (Schiffn.) J. R. Bray & D. C. Cargill, Riccia sorocarpa Bisch., Riccia bifurca Hoffm. and Riccia subbifurca Warnst. ex Croz.), typically growing on patches of bare ground, usually in damp micro-depressions subject to trampling. Notably, the invasive grass Paspalum paspaloides (Michx.) Scribn was recorded on the same local- Fig. 1. All known localities of Corrigiola litoralis in Croatia (from the top downwards: Krk, Unije, Molat, Korčula, Lastovo); our re- cord is denoted with a red dot. The years of the last known field confirmations are shown. Fig. 2. Aerial photographs of Molat, showing the exact location of Corrigiola litoralis in Zapuntelsko polje. CORRIGIOLA LITORALIS IN CROATIA ACTA BOT. CROAT. 77 (1), 2018 107 ity, aggressively occupying the area around the pond, as well as other moist micro-depressions in near vicinity. Another invasive species, Aster squamatus (Spreng.) Hieron, was also recorded in the area. Due to the extremely low number of findings in Croa- tia, and the affiliation with specific microhabitats, C. litora- lis is presumably threatened with extinction, and should be evaluated according to the IUCN criteria. At the best, even without insights into the current state of the population or its habitats, assuming that the species is still present in all historically known sites, it could qualify as vulnerable (VU) according to criterion D (IUCN 2013). In order to obtain more comprehensive data on the Croa- tian distribution of C. litoralis, historical localities should be searched for the presence of its populations, since only re- cords from Molat and Lastovo have been confirmed within the last 50 years. In particular, other temporary ponds along the eastern Adriatic coast, including the islands, should be carefully studied. Mediterranean temporary ponds are, be- yond any doubt, globally significant in the context of the preservation of rare and endangered species (Zacharias et al. 2007). Unfortunately, these habitats are simultaneously facing a rapid decline worldwide (Rhazi et al. 2012), accord- ingly being listed as a priority habitat in the Habitats Direc- tive (NATURA 2000 priority habitat type 3170, Anonymous 2007). Other rare/endangered plants with similar ecologies, such as Pilularia minuta Durie ex. A. Braun, Cicendia filifor- mis (L.) Delarbre, Damasonium polyspermum Cosson, Cryp- sis aculeata (L.) Aiton, Crypsis schoenoides (l.) Lam., Fimbri- stylis bisumbellata (Forssk.) Bubani, Lythrum tribracteatum Salzm. ex Spreng. etc., are typically recorded in these and similar habitats (Nikolić and Topić 2005, Anonymous 2007, Topić and Vukelić 2009, Boršić and Posavec Vukelić 2012, Vuković and Jelaska 2015), within ephemeral communities or their fragments. Due to their specific ecological require- ments, the survival of these species and communities is not supported beyond the very specific conditions of the corre- sponding habitats. Keeping this in mind, it is strongly ad- visable to study these species, including Corrigiola litoralis, more closely. For the future, we propose careful studies of Mediterranean temporary ponds through fieldtrips during the droughty period when ephemeral plants and mosses can be detected and recorded, their population size estimated, and threats identified. To monitor their population trends and quantify the level of habitat loss, we advise these activi- Fig. 3. A temporary pond in Zapuntelsko polje (Molat) where Corrigiola litoralis occurs, photographed in 2015. (a) 28th February, (b) 09th April, (c) 08th June, (d) 25th October (time of our visit). Photos by Z. Sedlar. Fig. 4. Corrigiola litoralis in bloom, on 25th October 2015. Photo by A. Alegro. VUKOVIĆ N., ŠEGOTA V., ALEGRO A., SEDLAR Z. 108 ACTA BOT. CROAT. 77 (1), 2018 ties be performed periodically (preferably yearly). 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