Bituminaria tunetana C. Brullo, Brullo, Cambria, El Mokni & Giusso, 2017

Brullo, Cristian, Brullo, Salvatore, Cambria, Salvatore, Mokni, Ridha El, Aouni, Mohamed Hédi El & Galdo, Gianpietro Giusso Del, 2017, A new species of Bituminaria (Fabaceae) from Tunisia, Phytotaxa 297 (3), pp. 221-233 : 222-230

Bituminaria tunetana C. Brullo, Brullo, Cambria, El Mokni & Giusso sp. nov. —Figs. 1,2

Diagnosis: — Species Bituminaria basaltica similis sed stipulis longioris, limbo foliolorum usque ad 70 mm longo, lanceolato vel linearilanceolato, mucro usque ad 1,2 mm longo, racemo longiore, corolla roseo-lilacina, longiore, vexillo majore, retuso apice, carina longiore, tubo staminali longiore, legumine longiore differt, etiam a Bituminaria bituminosa limbo foliolorum sparsim piloso, apice rotundato vel acuto, mucro 0,5–1,2 mm longo, racemo breviore, 4–12 floribus, calice breviore, corolla roseo-lilacina, vexillo spathulato breviore, ala et carina breviore, legumine et semine breviore divergens.

Type:— TUNISIA. Tunis, 90–100 m a.s.l., July 2015, 36°50’82”N 10°08’29”E, Ridha El Mokni s.n.(holotype CAT!, isotypes CAT!).

Description:— Herb perennial, woody and branched at the base, green, appressed-hirsute, up to 50 cm tall, no or faint smelling of pitch. Stems numerous, erect or ascending, rigid, striate. Leaves long petiolate, digitately 3-foliate; stipules linear-triangular, hairy, 5-8 mm long, adnate to the petiole; petiole 3–12 cm long; leaflets lanceolate to linear-lanceolate, 25–70 x 5–20 mm, sparsely hairy on both faces, rounded to acute and mucronate at the apex, with mucro 0.5–1.2 mm long, the central leaflet longer and petiolate, the lateral ones shorter and subsessile. Raceme subcapitate, 1.5–2 cm long, 4–12-flowered, covered by white and black hairs in the bracts, calyxes and upper part of peduncle; peduncles 8–14 cm long, longer than the leaf. Bracts 5–8 mm long, 1–3-toothed. Calyx 11–12 mm long, 10-nerved with unequal triangular-subulate teeth; tube 4–5 mm long; lower tooth 7–8 mm long; lateral teeth 5.5–7 mm long. Corolla pinkish-lilac, 13–14 mm long, longer than the calyx; standard spathulate, slightly retuse at the apex, 13–14 x 6–7 mm, pinkish-lilac above and white below, slightly tinged with lilac in the claw; wings 12–12.5 mm long, with limb pale lilac, 3–3.2 mm wide; keel 9–10 mm long, with limb 1.8–2 mm wide, having a macula dark violet above. Staminal tube 8.5–9 mm long; anthers 0.5–0.6 mm long. Pistil 8–8.5 mm long, hairy in the ovary and lower part of the style; stigma subcapitate, ciliate at the base. Pod indehiscent, exserted from the calyx, 13.5–14.5 mm long (beak included), densely covered in the corpus by setaceous hairs, 0.5–3 mm long, mixed to some rigid black prickles; beak flat, falcate, 9–10 mm long, hairy below and ciliate at the margin. Seed adherent to pericarp, laterally compressed, subreniform, 3.5–4.5x 2.8–3 mm, blackish-brown.

Seed and pod micro-morphology: —According to literature ( Barthlott 1981, Koul et al. 2000 and Celep et al. 2012, Fitsch et al. 2006, Kasem et al. 2011), the micro-sculptures occurring in the seed testa observable through the scanning electron microscopy (SEM), add significant information for the taxonomic treatment and the identification of a given species. In particular, many authors have carried out researches on the seed ornamentations of Fabaceae (see Murthy and Sanjappa 2002, Kirkbride et al. 2003, Salimpour et al. 2007, Bacchetta & Brullo 2010, Fawzel 2011, Gandhi et al. 2011, Brullo et al. 2011, 2013), emphasizing their important role in the systematic and phylogenetic approach inside of the genera or critical groups. As concerns Bituminaria, SEM investigations on the seed testa were performed only by Minissale et al. (2013), Giusso et al. (2015), Brullo et al. (2016) and Bogdanović et al. (2016) regarding B. bituminosa , B. basaltica , B. kyreniae , B. palaestina and B. plumosa . An examination of the seed coat of B. tunetana showed that the micro-sculptures of this species are very different from those ones of the aforesaid species. In fact, B. tunetana shows seed coat characterized by a fine and often lacerate reticulum bounding the single cells, which are irregularly polygonal (triangular to pentagonal) and 3.5–8 μm wide. The anticlinal walls are slightly grooved, rugose and more or less lacerate, while the periclinal ones are flat with epidermis slightly scabrous ( Fig.3 , A–B). Some differences occur also in the pod indumentum, since the hair surface of the corpus of B. tunetana is deeply rugose-foveolate, while the hairs are slightly rugose and have the longitudinal furrow moderately widened at the foot, with a basal diameter of ca. 30 μm ( Fig.3 , C–D).

Distribution and ecology: — On the basis of current knowledge, Bituminaria tunetana seems to be confined to the central and northern part of Tunisia ( Fig. 4), since no herbarium specimens from neighboring countries (e.g. Libya, Morocco or Algeria) can be attributed to B. tunetana . It typically grows on several types of substrata with dry soils, at an elevation of 20– 500 m. The plant is chiefly localized in synanthropic habitats, such as road sides, uncultivated fields, wadi pebbly bed, tree orchards, etc. From the bioclimatic viewpoint ( Rivas-Martinez et al. 2004), it is distributed within the thermo-Mediterranean belt, with sub-humid to arid ombrotypes ( You et al. 2016), while according to the Emberger classification it falls between the semi-arid to arid belt ( Anonymus 1976).

Etymology: —The specific epithet refers to “Tunetia”, latin name of Tunisia.

Phenology: —Flowering April to early June, fruiting June to July.

Discussion: —According to literature, herbarium investigations and morphological observations on numerous living plants cultivated from seeds collected in several Mediterranean localities ( Morocco, Spain, Baleares, Corsica, Sardinia, Sicily, Italian Peninsula, Croatia, Greece, Cyprus, Turkey, Israel, Jordan, etc.) and Canary Islands, Bituminaria tunetana is well differentiated from the other known species of this genus ( Tab. 2). In particular, it differs from B. bituminosa s. str. and also from the other known species mainly for leaves usually lanceolate to linear-lanceolate, sparsely hairy on both sides and corolla pinkish-lilac ( Fig. 5 ). Besides, B. tunetana for its very small flowers shows closer relationships with B. basaltica , endemic to Filicudi island (Aeolian Archipelago), but a lot of significant features allows to separate very well the two species. B. basaltica differs mainly in having stipules shorter, leaflets roundedelliptical to linear, 8–55 mm long. with mucro up to 0.8 mm long, raceme 1–1.6 cm long, corolla white, subequalling the calyx, standard 11–13 mm long, rounded to obtuse at apex, wings 10–11 mm long, keel 7.5–8.5 mm long, staminal tube 7–8 mm long, pod (included beak) 9–10 mm long, with beak 5.5–6 and seeds smaller ( Minissale et al. 2013). Another species quite related to B. tunetana is B. flaccida , rare chasmophyte known from few locality of the Middle East ( Jordan and Sinai), with which it has in common especially the pale colour of the corolla, the few-flowered inflorescences as well as the beak length and pod indumentum. However, several features allow to distinguish very well the two species especially for the habit, leaf shape and size, flowers, pods and seeds. In particular, B. flaccida is differentiated by grey-glaucous habit, leaflet densely hirsute, smaller, suborbicolar to obovate, only the upper ones are linear-lanceolate, 4–30 mm long, with petiole max. 7.5 mm long, raceme few-flowered (2–8), with longer peduncle (14–24 mm), calyx with shorter teeth, corolla withish-pink, with standard ovate-elliptical, 16–19 mm long and wing 15.5–16.5 mm long, pods included beak longer (15–16 mm) and seeds larger.

Finally, we found some herbarium specimens from Tunisia which are not referable to B. tunetana , but whose proper identification requires further investigations, especially on living material. Given that, the occurrence of the typical B. bituminosa in Tunisia cannot be excluded so far.

Additional specimens examined: TUNISIA. In arboretis Zaghouan, 6 July 1854, Kralik s.n. (P!) ; Zaghouan, 31 May 1883, Cosson, Letourneux, Reboud, Barratte & Bonnet. s.n. (P!) ; Ain Cherichira Ouest de Kairouan, 30 June 1883, Cosson, Letourneux, Reboud, Barratte & Bonnet. s.n. (P!) ; Guoeloat Kebiba, ad rupes septentrionem Dersus , 14 May 1886, Kralik s.n. (P!) ; Djebel Zaghouan, 7 july 1884, Kralik s.n. (P!) ; Gamarth , bord de route, May 1955, Pottier-Alapetite s.n. ( MPU!) ; Sidi Hossen à Tunis, 5 May 1883, Cosson, Letourneux, Reboud, Barratte & Bonnet s.n. (P!) ; Ad rupes in cacuminal collis prope Technis ( Matmata ), 1 April 1887, Letourneux s.n. (P!) ; Ras Kamat , 20 April 1888, Barratte s.n. (P!) ; Djebel Abat-er-Rahman El-Mekki Presqu’ile du Cap , 22 May 1883, Cosson, Letourneux, Reboud, Barratte & Bonnet s.n. (P!) ; Oued Ounim Mezenar , 29 April 1894, Letourneux s.n. (P!) ; In pascuis desertis apud Beni-Zid ad pedes Djebel Azizza , 14 May 1854, Kralik s.n. (P!) ; In alluvie oued Gabes, 6 May 1854, Kralik 208 (P!). Prov. Kairouan 30 km sw of Kairouan towards Haffouz , olive orchad sand soil, 276 m, 9 May 2005, Rico et al. 1853 ( K!) ; Prov. Ben Arous, near Hammam Lif Djebel Bougarni , hillside with Acacia, Juniperus and Pinus , alluvial soil, clay loam, 60 m, Rico et al. 1806 ( K!) ; C. 11 km from Ousseltia on C99 road (Michelen map) to Kairoun , 500 m, calcareous fallows field, 3 May 1975, Davis & Lamond D 57170 (E!) ; Tunetia bor., Hammam-el-Lif pr. opp. Tunis, in marg. vie, 31 March 1924, Lindberg s.n. (H!) ; Tunis, 50–60 m a.s.l., July 2015, Ridha El Mokni s.n. ( CAT!) ; Tunis, cultivated material from seeds collected by Ridha El Mokni, 10 May 2016, S. Brullo s.n. ( CAT!) .

Figures

FIGURE 3. SEM micrographs of the seed coats (A–B) and pod indumentum (C–D) of Bituminaria tunetana. A. Seed at low magnification (x 15). B. Seed coat at high magnification (x 2500). C. Pod at low magnification (x 10). D. Pod indumentum at high magnification (x 700). Material coming from type locality (CAT!).

FIGURE 5: Phenological features of Bituminaria tunetana (cultivated plant coming from the type locality) and of B. bituminosa (from Catania, Sicily). A. Detail of flowered stems of B. tunetana. B Inflorescence detail of B. tunetana. C Stems and leaves of B. bituminosa. D. Inflorescence detail of B. tunetana (left) and of B. bituminosa (right). (Photos by S. Cambria).