Brassica trichocarpa C. Brullo, Brullo, Giusso & Ilardi, 2013

Brullo, Cristian, Brullo, Salvatore, Galdo, Gianpietro Giusso Del & Ilardi, Vincenzo, 2013, Brassica trichocarpa (Brassicaceae), a new species from Sicily, Phytotaxa 122 (1), pp. 45-60 : 47-52

Brassica trichocarpa C. Brullo, Brullo, Giusso & Ilardi , sp. nov. ( Fig. 1 , 2 )

Species B. oleracea similis sed dense pilosa, petalis luteis, ovario dense ciliato-piloso praecipue secus suturas et costas, siliqua difficulter dehiscente, breviore, subglobosa usque ad ellipsoidea, dense pilosa, valvis incrassatis, induratis, spongiosis, superficie exteriore uniformiter laevi non torulosa, rostro lineari-subulato, differt.

Type: — ITALY, Sicily: Creste calcaree nei pressi di Monte Cuccio, presso San Martino delle Scale (Palermo), circa 900 m. di quota, 27 June 2011, S . Brullo e V. Ilardi s.n. (holotype CAT!, isotypes CAT!, FI!)

Suffrutex hairy, 70−120 m tall, with a robust main stem, branching often from the base. Stem woody, up to 25 mm in diameter at the base, green-purplish to purple mainly in the inflorescence. Leaves rigid, lightly thickened, green-glaucescent, more whitened in the abaxial face, often purplish at the margin, densely covered by rigid, simple hairs; basal and lower cauline leaves 10−30 cm long (including petiole), with petiole 3−9 cm long and lamina ovate to ovate-lanceolate, 7−20 × 6−13 cm, lobate or basally pinnatifid and pinnatisect, with lobes rounded or slightly obtuse at apex and petiole in upper part often with 1−2 pairs of small lobes, never winged or auriculate at base; margin irregularly and coarsely dentate; midrib strong with conspicuous lateral veins; upper cauline leaves gradually smaller, shortly petiolate to sessile, with lamina often linear, entire, only 2−3 cm long. Inflorescence loosely paniculate, branched from the base, pyramidate. Pedicels 10−19 mm long, hairy, patent or subpatent at anthesis. Sepals dark yellow to yellow-greenish, hairy outside, the outer ones ovate-lanceolate, 11.5−12.5 × 3.2−3.8 mm, the inner ones linear to linear-lanceolate, 11−12 x 2−2.4 mm, cucullate, slightly saccate at base. Petals spathulate, yellow, 20−22-mm; claw 6−7 mm long; limb 8−8.5 mm wide, rounded. Stamens exserted 1−2 mm above the petal disc; outer filaments whitish, 6−7.5 mm long; inner filaments 6.5−8 mm long; anthers yellow, 4.5−5 mm long, with a conspicuous connective tip. Pistil shorter or subequalling the stamens; ovary 2.2−3.7 mm long, white greenish, densely ciliate along the sutures and midribs and pubescent on the valves; style green, often tinged with purple, 2−2.5 mm long, subcylindric; stigma 0.7−0.8 × 1−1.2 mm, subcapitate, minutely papillose, yellow greenish. Basal glands dark green, 0.8– 0.9 mm in diameter. Fruiting pedicels 1.2−2.2 cm long, patent to erect-patent, usually purplish. fruits difficulty dehiscent, with corpus subglobose to ellipsoid, smooth not torulose, hairy, tinged with dark purple, 8−18 × 8−11 mm, with valves thickened, hardened, spongy, smooth and furrowed along the sutures at maturity, while it shows 4 ribs in correspondence of midribs and sutures when dry; rostrum linear-subulate, 5− 7 mm long, seedless. Seeds 4−16, subglobose, 2−2.5 mm in diameter, brown-reddish, minutely reticulate, arranged in 2 rows in each loculus.

Phenology: —Flowering May to early June, fruiting late June to July.

Seed morphology: —Shape and coat micro-morphology of seeds, based on SEM investigations, may be used as additional taxonomic feature for the identification of the taxa belonging to the genus Brassica , besides being useful for delimiting sections and genera. Seed sculptures are usually considered as a conservative and stable character, having relevant taxonomical and phylogenetic implications. In particular, several studies on the genus Brassica have emphasized the important role that the seed testa plays for its taxonomical treatment ( Stork et al. 1980, Snogerup et al. 1990, Koul et al. 2000, Tantawy et al. 2004, Zeng et al. 2004, Kasem et al. 2011). In particular, seed coat of B. trichocarpa is regularly reticulate, with polygonal cells, 40-70 µm wide, the anticlinal walls are raised, more or less regular, broad, with striate-rugose tops, the outer periclinal cell are slightly depressed and finely rugose, often with a small eccentric knob ( Fig. 3A ). Based on personal observations and literature, seeds of B. trichocarpa are well differentiated from those ones of other taxa of B. sect. Brassica . In particular, the reticulate pattern of B. trichocarpa is rather similar to that one of B. villosa subsp. tinei ( Fig. 3D ) and B. rupestris subsp. rupestris ( Fig. 3E ), but both are well differentiated in having irregular anticlinal walls with quite variable thickness and marked rugosity, as well as the outer periclinal cells are deeply depressed with a central knob. Much more differentiated are the seeds of B. villosa subsp. villosa ( Fig. 3B ) and B. macrocarpa ( Fig. 3C ), both showing a great morphological affinity with B. trichocarpa . In fact, both have seed coat cells with very irregular boundaries, as well as not well defined anticlinal and periclinal walls.

Distribution and ecology:—The species grows exclusively near Mt. Cuccio, a small mountain close to Palermo (N Sicily) in the central Mediterranean, where it colonizes the rocky edges at about 900 m of elevation ( Fig. 4 ). This is a suffruticous plant linked to carbonatic stands affected by strong winds and more or less constant misty regime due to proximity of the Tyrrhenian Sea. The population of B. trichocarpa is represented by few (less than 50) and scattered individuals occurring within the thermo-xeric grasslands dominated by Ampelodesmos mauritanicus T. Durand & Schinz (1894: 874) , huge caespitose grass widely spread all over the island ( Brullo et al. 2010).

Etymology:—The specific epithet refers to the presence of hairs on the carpels, from the ancient Greek trichos (= hair) and carpos (= fruit).

Conservation status:—According to IUCN Red list category ( IUCN 2011), this species for its rarity, number of individuals and punctiform distribution (4-5 ha) can be considered as Critically Endangered: CR B2a, b(v), D.

Figures

FIGURE 1. Diagnostic morphological features of Brassica trichocarpa. A. Flower, upper view. B. Flower, lateral view. C. Bud. D. Petals. E. Outer sepals. F. Inner sepals. G. Stamens and pistil. H. Anthers, dorsal and ventral view. I. Pistils. J. Inner gland. K. Outer gland. L. Dried fruit, dorsal view. M. Dried fruit, lateral view. N. Dried fruit, cross-section. O. Fresh fruit, lateral view. P. Fresh fruit, cross-section. Q. Seeds. Illustration by Salvatore Brullo based on S. Brullo & V. Ilardi s.n. (CAT!) and C. Brullo, S. Brullo, G. Giusso del Galdo & V. Ilardi s. n. (CAT!).

FIGURE 2. Leaf variability of Brassica trichocarpa. Illustration by Salvatore Brullo based on C. Brullo, S. Brullo, G. Giusso del Galdo & V. Ilardi s. n. (CAT!).

FIGURE 3. SEM micrographs of seed surface at different magnification of A. Brassica trichocarpa (from the type locality: Mt. Cuccio, Palermo,). B. B. villosa subsp. villosa (from the type locality: Mt. Occhio, Palermo). C. B. macrocarpa (from the type locality: Favignana, Egadi Islands). D. B. villosa subsp. tinei (from the type locality: Marianopoli, Palermo). E. B. rupestris subsp. rupestris (from the type locality: Mt. Pellegrino, Palermo).

FIGURE 4. Phenological features of Brassica trichocarpa. A. Flowered plant in natural habitat. B. Basal leaves. C. Fructified inflorescence. D. Inflorescence. E. Open flower with pistil. F. Fruit. G. Fruit (cross section). H. Fruit (longitudinal section) (Photos by V. Ilardi).