Plantago tunetana Murbeck,

Ltaeif, Hela Belhaj, Sakhraoui, Anis, Hassemer, Gustavo, Castillo, Jesús M., Elimem, Mohamed & Rouz, Slim, 2023, Plantago tunetana (Plantaginaceae) in Tunisia: notes on its morphology, distribution, and ecology, Phytotaxa 600 (3), pp. 195-205 : 196-200

Plantago tunetana Murbeck,

Contrib. ä la Connaiss. de la Flore du Nord-Ouest de l’Afr. et plus spec. de la Tunisie III: 2, T. 10 Fig. 5 –8 (1899)

Type (lectotype, designated here):— TUNISIA. Souk-el-Djema, in campis argillosis, 5 June 1896, Murbeck s.n. [ LD1221559 ! ( Fig. 1 ), isolectotype P00466350 ! (image of the isolectotype available at https://science.mnhn.fr/taxon/species/plantago/tunetana?lang=en_ US)].

Notes on typification:— Murbeck (1899: 2–3) did not cite any original specimen in the protologue of Plantago tunetana . A provenance was provided: “ Tunisie centrale: Collines calcaires, champs argileux, etc. entre Maktar et Souk-el-Djema, c. 1000 m.”. In addition, an illustration (“Tab. Nostra X figs. 5–8) was provided and it is part of the original material for the name. We traced two specimens at LD (barcode LD1221559 ) and P (barcode P00466350 ) which are also original material. Svante Samuel Murbeck (1859–1946) lived and worked in or around Lund during most of his life, including the time when P. tunetana was published. For this reason, we here designate the specimen in LD as the lectotype ( Fig. 1 ). LD1221559 bears two plants that are well-preserved and morphologically complete, which match the Murbeck’s description and correspond to the current application of the name.

Description:—Perennial, roots thick woody. Leaves ovate or lanceolate–oblong, obtuse or short blade (4.0– 7.6 cm × 0.6–2.0 cm) with sinews 7 raising transmitted by base petiole broad. These leaves are obtuse at the apex, or suddenly contracted into a very short deflecting blade often slightly wavy at the edges, mostly entire or remotely denticulate especially at the veins, which are covered with very fine, soft hairs, the younger silky white, the more mature green. Scapes (3.6–12.0 cm) arched or subrogate, densely pubescent. Spikes cylindrical elongated or oblong, shorter than the scapes (1.4–3.6 cm long). Bracts lanceolate (3.51–3.83 mm × 2.13–2.33 mm) and villous on the outside, pale green behind, and white or brownish towards the margins. Sepals equal, lanceolate or ovate-lanceolate (5.23–6.09 mm × 1.93–2.28 mm), pointed, villous behind and at the apex, towards the margins with a whitish membrane, all free with an unkeeled back. Corolla tube glabrous, 5.0– 5.5 mm long. Corolla lobes very broad or reflexed, triangular or ovate-lanceolate (3.25–3.76 mm × 2.07–2.54 mm), gradually tapering in acuity, dark brown above, below with long, densely hairy silky hairs. Seeds smooth (3.25–3.54 mm × 1.32–1.42 mm), deeply grooved inner surface with sub-cymbiform.

Etymology:—The specific epithet refers to “Tunetia”, a Latin name for Tunisia.

Taxonomic relationships:— Plantago tunetana belongs to P. subg. Albicans Rahn (1996: 185) sect. Albicantes Barnéoud (1844: 18) ser. Ciliatae Rahn (1996: 188) . According to Murbeck (1899), this species shares remarkable similar affinities with P. albicans and P. cylindrica (Forsskal 1775: 31) . These two species differ from P. tunetana by the presence of three to five raising veins on the abaxial face of blade leaves, less rapidly acuminate, linear or linearlanceolate. In addition, P. albicans differs considerably by its glabrous broadly oval corolla and by their seeds at most 2.5 mm long ( Figures 1−6 ) ( Table 2 ) ( Murbeck 1899, Shipunov 2020).

Phenology:—Flowering in late spring (April–)May–July, fruiting in July–August(–October).

Distribution and ecology:— Rahn (1996) stated that Plantago tunetana was found in restricted areas in the mountains in north-west Africa. In Tunisia, P. tunetana was found only within roadsides in Gouraïa (about 100 plants), Kef (35°51’30.39” N; 8°41’04.72” E; 720 m a.s.l.) ( Fig. 7 ). In Gouraïa, P. tunetana was observed growing on a silty clay soil, 10% of pebbles, nitrogen (33.83–34.87 ppm), phosphorus (36.67−38.71 pmm), potassium (99.47−102.19 ppm) content, organic matter (0.31−0.47%), soil pH (8.15−8.39); electrical conductivity (0.97−1.02 g /L), total limestone (42.77−44.43%), and active limestone (19.86−20.88%), being either totally exposed to the sun or partially exposed due to the presence of Olea europaea Linnaeus (1753: 8) subsp. europaea . We found only one population composed of a few adult individuals growing as isolated rosettes. The site was cultivated with O. europaea subsp. europaea . We recoded the presence of Avena fatua Linnaeus (1753: 80) , Silybum marianum Linnaeus (1753: 823) Gaertner (1791: 378) , Bromus scoparius Linnaeus (1755: 6) . The climate of the area is typically high semi-arid with fresh winter ( Verner et al. 2018).

Conservation status:—According to the IUCN Red List criteria ( IUCN 2019), this species should be considered as Critically Endangered (CR B2a, b ii, iii, iv, v; C1a ii, b) in Tunisia. The habitat of Plantago tunetana is currently threatened by the expansion works of the road linking Dahmani to Djérissa (code P18), which passes through Gouraïa. Because this construction will require more space to widen the road, at least a part of the roadside will have to be removed, threatening the species with extinction. Therefore, the inclusion of P. tunetana in the “Taxon’s at risk of disappearance through serious rarefaction” of the Tunisian Flora ( Le Floc’h et al. 2010) is crucial in our opinion. We recommend more collection efforts in the neighbouring area, in search for other possible populations of P. tunetana . This species should be the target of in-situ conservation efforts (microreserves, recovery of the habitats, use of targets to assess the success or failure of interventions in biodiversity conservation) and its seeds must be collected and cryopreserved ex-situ to increase their survival and natural regeneration.

Notes on the associated species with Plantago tunetana in Tunisia:— Plantago tunetana occurs in degraded shrub community, dominated by some woody species. These communities consist of a tree layer dominated by Olea europaea subsp. europaea with a canopy cover of approximately 60%, whereas on herb layer several species which are common in opened, degraded, grazing Mediterranean areas take place, such as Avena fatua , Silybum marianum , and Bromus scoparius ( Table 2 ). The full records of plants abundance/dominance are reported in Table 2 . All the recorded species were native.

Figures

FIGURE 1. Lectotype of Plantago tunetana (S.S. Murbeck s.n., LD-1221559). Copyright: Lunds Universitet.

FIGURE 5. (A) Orbicular bracts in Plantago albicans and (B) lanceolate bracts in P. tunetana, showing a green nerve widest near apex.

FIGURE 7. Locality of the sampling site in Gouraïa KEF North-West of Tunisia.