ARTÍCULO

Taxonomic and distributive notes on Serapias lingua subsp. tunetana (Orchidaceae), a rare endemic to Tunisia

R. EL MOKNI^1,2,3 & G. DOMINA⁴

¹ University of Carthage, Laboratory of Botany and Plant Ecology (SNA-214), Department of Life Sciences, Faculty of Sciences of Bizerte, Jarzouna, TN-7021 Bizerte, Tunisia

² University of Jendouba, Laboratory of Silvo-pastoral Resources, Silvo-Pastoral Institute of Tabarka, BP. 345, TN-8110 Tabarka, Tunisia

³ University of Monastir, Laboratory of Botany, Cryptogamy and Plant Biology, Faculty of Pharmacy of Monastir, Avenue Avicenna, TN-5000 Monastir, Tunisia

⁴ University of Palermo, Department of Agriculture, Food and Forest Sciences, viale delle Scienze, bldg. 4, IT-90128 Palermo, Italy

ORCID iD. R. EL MOKNI: https://orcid.org/0000-0003-3849-1039, G. DOMINA: https://orcid.org/0000-0003-4184-398X

Author for correspondence: G. Domina (gianniantonio.domina@unipa.it)

Editor: L. Sáez

Received 10 August 2018; accepted 2 October 2018; published on line xxxx

Taxonomic and distributive notes on Serapias lingua subsp. tunetana (Orchidaceae), a rare endemic to Tunisia

ABSTRACT
Taxonomic and distributive notes on Serapias lingua subsp. tunetana (Orchidaceae), a rare endemic to Tunisia.— Serapias lingua subsp. tunetana, a rare endemic orchid confined to Tunis, northern of Tunisia, has been rediscovered far away from its type locality nearly after 22 years. Since its first finding in 1996 and its description published in 2005, the subspecies has not been found again, and was presumed to be extinct, or the taxon was erroneously identified. A detailed description of the subspecies justifying an amendment to its description, a map of its current distribution and colour photographs are also provided. The affinities to the related taxa within the S. lingua group occurring in Tunisia are here presented. The global IUCN status for this taxon is evaluated.
KEY WORDS: chorology, conservation, endemism, Orchidaceae, Serapias.

Notas taxonómicas y distributivas sobre Serapias lingua subsp. tunetana (Orchidaceae), una rara especie endémica de Túnez

RESUMEN
Notas taxonómicas y distributivas sobre Serapias lingua subsp. tunetana (Orchidaceae), una rara especie endémica de Túnez.— Serapias lingua subsp. tunetana, una rara orquídea endémica con área de distribución restringida en Túnez, al norte de Túnez, ha sido redescubierta lejos de su localidad tipo después de 22 años. Desde su primer hallazgo en 1996 y su descripción publicada en 2005, la subespecie no se había encontrado nuevamente y se presume que se extinguió o fue identificada erróneamente. En este trabajo se proporciona una descripción detallada de la subespecie que justifica una enmienda a su descripción, y se aporta asimismo un mapa de distribución y varias fotografías. Se listan las principales afinidades de la subsp. tunetana con los táxones más estrechamente relacionados dentro del grupo de S. lingua que se distribuyen en Túnez. Se evalúa su estado de conservación atendiendo a los criterios y categorías de la UICN.
PALABRAS CLAVE: conservación, corología; endemismo, Orchidaceae, Serapias.

CONTENIDOS

INTRODUCTIONTop

The genus Serapias L. (Orchidaceae) comprises about 26–30 species (Nelson, 1968Nelson, E. 1968. Monographie und Ikonographie der Orchideen-Gattungen Serapias, Aceras, Loroglossum, Barlia [Monograph and iconography of the orchid genera Serapias, Aceras, Loroglossum, Barlia]. G. & A. Claraz-Schenkung, Zürich [in German].; Baumann & Künkele, 1989Baumann, H. & Künkele, S. 1989. Die Gattung Serapias L. eine taxonomische Übersicht [The genus Serapias L. A taxonomic overview]. Mitteilungsblatt, Arbeitskreis Heimische Orchideen Baden-Württemberg 21: 701–946 [in German].; Baumann et al., 2006Baumann, H., Künkele, S. & Lorenz, R. 2006. Orchideen Europas (Naturführer) [Orchids of Europe (nature guide)]. Eugen Ulmer, Stuttgart [in German].; Delforge, 2016Delforge, P. 2016. Guide des orchidées d’Europe, d’Afrique du Nord et du Proche-Orient (4th ed.). [Guide of orchids of Europe, North Africa and Middle East]. Delachaux et Niestlé, Lonay [in French].) with mainly Mediterranean distribution, although some species reach the west of the Atlantic coast. Its range extends from the Azores and the Canaries in the west to the Caucasus, and in the east and north as far as Brittany (France) (Gölz & Reinhard, 1980Gölz, P. & Reinhard, H. R. 1980. Serapias (Orchidaceae). Ergebnisse statistischer und chorologischer Untersuchungen [Serapias (Orchidaceae). Results of statistical and chorological examinations]. Mitteilungsblatt, Arbeitskreis Heimische Orchideen Baden-Württemberg 12: 123–189 [in German].; Pérez Chiscano et al., 1991Pérez Chiscano, J. L., Gil Llano, J. R. & Durán Oliva, F. 1991. Orquídeas de Extremadura. Fonda Natural, Madrid.; Delforge, 1995Delforge, P. 1995. Orchids of Britain & Europe. Harper Collins Publishers, New York., 2016Delforge, P. 2016. Guide des orchidées d’Europe, d’Afrique du Nord et du Proche-Orient (4th ed.). [Guide of orchids of Europe, North Africa and Middle East]. Delachaux et Niestlé, Lonay [in French].). In Tunisia, according to APD (2018APD [African Plant Database] 2018. Conservatoire et Jardin botaniques de la Ville de Genève and South African National Biodiversity Institute, Pretoria. Version 3.4.0. Retrieved August 8, 2018, from http://www.ville-ge.ch/musinfo/bd/cjb/africa ) this genus includes six species: S. cordigera L., S. lingua L., S. nurrica Corrias, S. parviflora Parl., S. stenopetala Maire & T. Stephenson, and S. strictiflora Veiga. Within Serapias lingua it is possible to distinguish S. lingua subsp. lingua, a Mediterranean-Atlantic taxon, and S. lingua subsp. tunetana B. Baumann & H. Baumann, a taxon endemic to Tunisia, little known among botanists, very rare and not seen since 2000. From taxonomic and nomenclatural point of view, some authors (e.g. Le Floc’h et al., 2010Le Floc’h, E., Boulos, L. & Véla, E. 2010. Catalogue synonymique commenté de la flore de Tunisie [Commented synonymic catalogue of the flora of Tunisia]. Banque Nationale de Gènes, Tunis [in French].; Véla et al., 2012Véla, E., Ouni, R. & Martin, R. 2012. Serapias nurrica Corrias (Orchidaceae), nouveau pour la flore de Tunisie [Serapias nurrica Corrias (Orchidaceae), new for the flora of Tunisia]. Journal Europäischer Orchideen 44: 381–392 [in French].; Martin et al., 2013Martin, R., Ouni, R., Véla, E. & Léger, J.-F. 2013. À la découverte des orchidées du Cap Bon en Tunisie: Une expérience de cartographie des orchidées sauvages [Discovering the orchids of Cap Bon in Tunisia: an experience of cartography of wild orchids]. Société Méditerranéenne d’Orchidologie, La Motte d’Aigues [in French]., 2015Martin, R., Véla, R. & Ouni, R. 2015. Orchidées de Tunisie [Orchids of Tunisia]. Bulletin de la Société Botanique du Centre-Ouest 44: 1–160 [in French].) considered S. lingua subsp. tunetana as synonym of S. strictiflora.

The discovery of three localities where S. lingua subsp. tunetana grows allowed us to conduct taxonomic and distributive observations on this taxon. This contribution is part of the project of floristic investigation of Tunisia conducted by the authors in the last years (e.g. Domina et al., 2015Domina, G., El Mokni, R., Greuter, W. & Raimondo F. M. (Eds.) 2015. Results of the 12th “Iter Mediterraneum” in Tunisia, 24 March–4 April, 2014. Bocconea 27: 1–76.; El Mokni et al., 2015aEl Mokni, R., Domina, G., Sebei, H. & El Aouni, M. H. 2015a. Taxonomic notes and distribution of taxa of Orobanche gr. minor (Orobanchaceae) from Tunisia. Acta Botanica Gallica: Botany Letters 162: 5–10. https://doi.org/10.1080/12538078.2014.993424, bEl Mokni, R., Domina, G., Sebei, H. & El Aouni, M. H. 2015b. On the distribution and subspecific variation of the Tunisian‒Algerian endemic Delphinium sylvaticum (Ranunculaceae). Nordic Journal of Botany 33: 548–554. https://doi.org/10.1111/njb.00900; Astuti et al., 2017Astuti, G., Brullo, S., Domina, G., El Mokni, R., Giordani, T. & Peruzzi, L. 2017. Phylogenetic relationships among tetraploid species of Bellevalia (Asparagaceae) endemic to south-central Mediterranean. Plant Biosystems 151: 1120–1128. https://doi.org/10.1080/11263504.2017.1320308).

MATERIALS AND METHODSTop

Systematic field excursions in the north of Tunisia were carried out in order to investigate taxonomy and distribution of taxa belonging to Serapias lingua gr. In Table 1 are presented the main morphological discriminant characters, and phenological and ecological traits between Serpias lingua subsp. tunetana and the taxonomic closest taxa occurring in Tunisia (S. lingua subsp. lingua and S. strictiflora). Characters of S. lingua subsp. tunetana were measured in the field; data of the other species result from literature (Lorenz, 2001Lorenz, R. 2001. Die Gattung Serapias in Italien: Arten und Verbreitung [The genus Serapias in Italy: species and distribution]. Journal Europäischer Orchideen 33: 235–368.; Baumann et al., 2006Baumann, H., Künkele, S. & Lorenz, R. 2006. Orchideen Europas (Naturführer) [Orchids of Europe (nature guide)]. Eugen Ulmer, Stuttgart [in German].; Venhuis et al., 2007Venhuis, C., Venhuis, P., Oostermeijer, J. G. B. & Tienderen, H. van 2007. Morphological systematics of Serapias L. (Orchidaceae) in Southwest Europe. Plant Systematics and Evolution 265: 165–177. https://doi.org/10.1007/s00606-007-0519-0; Martin et al., 2015Martin, R., Véla, R. & Ouni, R. 2015. Orchidées de Tunisie [Orchids of Tunisia]. Bulletin de la Société Botanique du Centre-Ouest 44: 1–160 [in French].; Delforge, 2016Delforge, P. 2016. Guide des orchidées d’Europe, d’Afrique du Nord et du Proche-Orient (4th ed.). [Guide of orchids of Europe, North Africa and Middle East]. Delachaux et Niestlé, Lonay [in French].). In order to assess the IUCN status (IUCN, 2012IUCN [International Union for Conservation of Nature] 2012. IUCN Red List categories and criteria. Version 3.2 (2nd ed.). IUCN Species Survival Commission. IUCN, Gland. Retrieved August 8, 2018, from http://jr.iucnredlist.org/documents/redlist_cats_crit_en.pdf ) of this taxon the Extent of occurrence (EOO) and the Area of occupancy (AOO) were calculated using the GeoCAT tool according to Bachman et al. (2011Bachman, S., Moat, J., Hill, A. W., Torre, J. de la & Scott, B. 2011. Supporting Red List threat assessments with GeoCAT: geospatial conservation assessment tool. In: Smith, V. & Penev, L. (Eds.), e-Infrastructures for data publishing in biodiversity science. ZooKeys 150: 117–126. https://doi.org/10.3897/zookeys.150.2109) calculated with a 2 × 2 km cell fixed grid.

RESULTS AND DISCUSSIONTop

The new findings were done on the course of botanical surveys in 2013 and 2014 in the north of Tunisia (Fig. 1). In 2013 the taxon was found in the Cap Bon peninsula, where some small, flowering individuals (Fig. 2) were recoded near the sea level, on Oligocene substrate within a loam-sandy depression of an acidic soil.

Figure 1. Distribution of Serapias lingua subsp. tunetana in Tunisia; the yellow dot indicates presumed locality discovered in 1996, whereas red dots indicate new discovered populations in the north of Tunisia, since April 2013. [View full size] [Descargar tamaño completo]

Figure 2. Serapias lingua subsp. tunetana from Cap Bon, northeastern Tunisia: (A), habitat and habit; (B), front view flower; (C), three-flowered inflorescence; (D), typical oval epichile (photographs: R. El Mokni, April 28, 2013). [View full size] [Descargar tamaño completo]

In 2014 this taxon was discovered in the Kroumiria region where two populations were found in Tabarka on loam to clay-sandy depressions and in Ain Draham on clay-loamy depressions extending both on numidic substrate (Oligo-Eocene).

Description: Plants with 2–3 subglobose or ovoid tubercules. Stem straight and cylindrical, 100–200 mm high, green and often spotted red at the base; 3–5 basal leaves, linear-lanceolate, 40–110 mm long and 6–11 mm broad, and 1–2 bract-like cauline leaves; inflorescence lax, bearing 2–4 slender flowers; bracts ovate-lanceolate, grey to red with reddish veins, 38–52 mm long and 12–22 mm wide; sepals and petals form a pointed hood, which is normally (sub-) horizontally positioned; sepals ovate-lanceolate, 15–25 mm long, green to red colored with pinkish to purple veins; petals usually shorter than sepals, from a purple, orbicular base acuminate into a slender labellum by a constriction divided into hypochile and epichile; hypochile 8–13 mm long and 18–24(26) mm wide; lateral lobes inwardly replicated but still largely visible, purple with a red colored center; hypochile with a deeply grooved stigmatic surface; epichile lanceolate, 14–19(20) mm long and 8–11 mm in width [for Baumann & Baumann (2005Baumann, B. & Baumann, H. 2005. Contributions to the knowledge of the orchid flora of Northwest-Africa. Journal Europäischer Orchideen 37: 915–938.) epichile measures only 4–7 mm —mean 5.4— in width and 7–10 mm —mean 8.7— long, see Table 1], red to dark red with very short yellowish to reddish hairs; ovary cylindrical, 18–24 mm (see Table 1).

Flowering & fruiting period: March–May.

Habitat: In Cap Bon, in slow-drainage clay-loamy depressions with thermophilous or ombrophilous vegetation, growing mainly with Cicendia filiformis (L.) Delarbre, Filago lojaconoi (Brullo) Greuter, Hypochaeris achyrophorus L., Lotus hispidus DC., Paronychia echinulata Chater, Plantago bellardii All., Romulea ramiflora Ten., Rumex bucephalophorus L. subsp. bucephalophorus and Trachynia distachya (L.) Link.

In Kroumiria, in slow-drainage clay-loamy depressions with hemi-ombrophilous vegetation, growing mainly with Cyperus sp. pl., Stachys arvensis (L.) L., Geranium dissectum L., Silene laeta (Aiton) Godr., Trifolium subterraneum L., Lotus hispidus DC., L. palustris Willd., or in sandy-clay dried depressions on prairial areas within ombrophilous vegetation, growing mainly with Bellis annua L., Trifolium campestre Schreb., T. micranthum Viv., Lythrum hyssopifolia L., Trachynia distachya (L.) Link.

Distribution: Endemic to North Tunisia: Cap Bon, West Nabeul, El Haouaria-Jbel Labiadh): 80–120 m a.s.l.; Kroumiria, East Tabarka, Ras-Rajel: 100–150 m a.s.l.; Ain Draham, Fej-Errih: 600–650 m a.s.l. (Fig. 1)

Specimens examined (new records): Tunisia: Nabeul: El Haouaria-Jbel Labiadh, 37° 02’ 42” N, 11° 04’ 12” E, 94 m, 28.IV.2013. R. El Mokni & G. Domina s.n. (PAL-Gr!). Jendouba: Tabarka-Ras Rajel, 36° 56’ 26” N, 08° 53’ 06” E, 137 m, 18.IV.2014, R. El Mokni. s.n. (Herb. Univ. Bizerta!); Ain Draham-Fej Errih, 36° 45’ 04” N, 08° 41’ 26” E, 607 m, 15.V.2014, R. El Mokni. s.n. (Herb. Univ. Bizerta!).

Conservation status: Serapias lingua subsp. tunetana is so far known only from one locality in Cap Bon and two in Kroumiria. All the populations were found on small areas of about 20 m² and represented by no more than a dozen of individuals each. According to Bachman et al. (2011Bachman, S., Moat, J., Hill, A. W., Torre, J. de la & Scott, B. 2011. Supporting Red List threat assessments with GeoCAT: geospatial conservation assessment tool. In: Smith, V. & Penev, L. (Eds.), e-Infrastructures for data publishing in biodiversity science. ZooKeys 150: 117–126. https://doi.org/10.3897/zookeys.150.2109) methodology there are: EOO = 1950 km² and AOO = 12 km². There is no detailed information available on population dynamics; however, due to its habitat, the population trend and the number of mature individuals can be considered stable.

The population in Cap Bon is located in an area near the sea, but future urban developments (i.e. construction of roads, buildings) could represent a potential threat to the population. The Red List category (IUCN, 2016IUCN [International Union for Conservation of Nature] 2016. The IUCN Red List of threatened species. Version 2015-4. Retrieved August 8, 2018, from http://www.iucnredlist.org ) here proposed for this taxon is: EN (Endangered) using the Criteria (Global Assessment): B1ab(iii)+D.

The most important conservation measure that we suggest is the habitat conservation. The areas were the found populations grow could be protected at local level according to the system of plant micro-reserves adopted in East Spain (Laguna et al., 2004Laguna, E., Deltoro, V. I., Pérez-Botella, J., Pérez-Rovira, P., Serra, L., Olivares, A. & Fabregat, C. 2004. The role of small reserves in plant conservation in a region of high diversity in eastern Spain. Biological Conservation 119: 421–426. https://doi.org/10.1016/j.biocon.2004.01.001).

Taxonomic notes: This taxon was described as Serapias lingua subsp. tunetana by Baumann & Baumann (2005) from Cap Bon Region. Two years later it was considered as a form, S. lingua f. tunetana by Delforge (2007Delforge, P. 2007. Serapias lingua f. tunetana (B. Baumann & H. Baumann) P. Delforge. Naturalistes Belges 88: 248.). Then, it was included in the synonymy of S. strictiflora, or of S. lingua subsp. duriaei (Rchb.) Maire by Le Floc’h et al. (2010Le Floc’h, E., Boulos, L. & Véla, E. 2010. Catalogue synonymique commenté de la flore de Tunisie [Commented synonymic catalogue of the flora of Tunisia]. Banque Nationale de Gènes, Tunis [in French].) and Martin et al. (2013Martin, R., Ouni, R., Véla, E. & Léger, J.-F. 2013. À la découverte des orchidées du Cap Bon en Tunisie: Une expérience de cartographie des orchidées sauvages [Discovering the orchids of Cap Bon in Tunisia: an experience of cartography of wild orchids]. Société Méditerranéenne d’Orchidologie, La Motte d’Aigues [in French]., 2015Martin, R., Véla, R. & Ouni, R. 2015. Orchidées de Tunisie [Orchids of Tunisia]. Bulletin de la Société Botanique du Centre-Ouest 44: 1–160 [in French].).

Serapias lingua subsp. tunetana, in our opinion, differs from S. lingua subsp. lingua and S. strictiflora [= S. lingua subsp. duriaei (Batt.) Soó] mainly by the shape and size of the lip (see Table 1 and Figs. 2, 3 and 4). The difference in the size of the epichile included in the original description by Baumann & Baumann (2005Baumann, B. & Baumann, H. 2005. Contributions to the knowledge of the orchid flora of Northwest-Africa. Journal Europäischer Orchideen 37: 915–938.; i.e. 7–10 × 4–7 mm) and that measured by us (14–19 × 8–11 mm) may due to the small number of observations made by the describing authors that accentuated the values measured on some individuals with smaller flowers, due to particularly dry years.

Figure 3. Serapias lingua subsp. tunetana from Kroumiria, northwestern Tunisia: (A), front view flower; (B), open flower with typical lanceolate epichile (photographs: R. El Mokni, May 15, 2014). [View full size] [Descargar tamaño completo]

Figure 4. Serapias lingua subsp. tunetana from Kroumiria, northwestern Tunisia: (A), habitat and habit; (B), a profile view flower; (C), typical narrowly triangular epichile (photographs: R. El Mokni, April 18, 2014). [View full size] [Descargar tamaño completo]

ACKNOWLEDGMENTSTop

Our best thanks are addressed to Dr. R. Lorenz for his collaboration, for his revision of the first version of this manuscript and for all his amending comments.

REFERENCESTop