Allium stamatiadae Trigas, 2020

Trigas, Panayiotis & Bareka, Pepy, 2020, Allium stamatiadae, a new species of A. sect. Codonoprasum (Amaryllidaceae) from Andros island (Aegean Archipelago, Greece), Phytotaxa 443 (3), pp. 287-294 : 288-291

Allium stamatiadae Trigas , sp. nov. ( Fig. 1 )

Allium stamatiadae is closely related to A. orestis , from which it differs in the scape inserted externally to the bulb (versus inserted centrally to the bulb), spathe valves similar to leaves (versus distinct from the leaves), pedicels 10–24 mm long, ± unequal (versus 14–70 mm long, remarkably unequal), tepals whitish tinged with brown or greenish-brown, becoming light purplish when withering (versus greenish-yellow tinged with purplish-brown).

Type: — GREECE. Kiklades: Andros island, ca 400 m SW of Vourkoti village, Platanus orientalis and Alnus glutinosa woodland along Vourkoti stream, siliceous substrate, 37°51.417’N, 24°53.095’E, 650 m elevation, 20 September 2019, Trigas & Zervakis 6625 (holotype ACA; isotype ATH).

Bulbous perennial herb. Bulb 1.2–2.3 × 0.9–2.2 cm, ovoid to subglobose; outer tunics coriaceous, pale grayish-brown; inner tunics whitish, membranous. Bulblets produced externally at the upper part of the bulb and the lower part of the scape, light brown to yellowish, acuminate, long-stalked. Scape 27–55 cm long, 4–6 mm in diameter at the base (including leaf sheaths) and 2–3 mm in diameter at the upper part, erect, glabrous, green to glaucous-green, robust, covered by leaf sheaths for 1/2–3/4 of its length, inserted externally to the bulb. Leaves 4–5, 35–50 cm long and 4–10 mm wide, glabrous, convex and ribbed abaxially, ± flat adaxially, fistulous. Spathe erect to slightly reflexed, longer than the inflorescence, with two unequal valves similar to leaves, the larger 14–35 cm long, 7–9-nerved and the smaller 9–24 cm long, 5–7-nerved; spathe appearing at early April with valves united only at base for 3–5 cm. Inflorescence lax, subhemispheric, 25–70-flowered, with ± unequal, suberect to spreading pedicels 10–24 mm long during flowering. Flowers campanulate; tepals 5.5–6.5 × 2.2–2.5 mm, oblong to narrowly elliptic, rounded and often shortly apiculate at the apex, whitish tinged with brown or greenish-brown, becoming light purplish after anthesis. Stamens included, with simple, white filaments 3.6–5.6 mm long, connate below into an annulus ca 1.5 mm long; anthers 0.7 × 0.3–0.4 mm, oblong-elliptical, whitish, rounded to apiculate at the apex. Ovary 3.0–4.0 × 1.5–2.0 mm, obovoid-cylindrical, narrowed at base, truncate and papillose above; style 1.0– 2.2 mm long, white. Capsule 5.4–6.5 × 4.3–5.4 mm, 3- valved, green, obovoid to subglobose. Seeds 3–4 × 2 mm, broadly falcate, black, rugulose.

Etymology: —Species name is dedicated to the memory of the Greek botanist Elli Stamatiadou (Andros 1933– Athens 2015), curator at the herbarium of Goulandris Natural History Museum (ATH) from 1965 to 2009.

Flowering and fruiting: —Flowering from late August to early October, fruiting in October-November.

Distribution: — Allium stamatiadae is currently known from two localities at the central part of Andros island. The type locality is the Vourkoti stream, and the species has also been collected by a stream close to the abandoned Evrousies village. The presence of A. stamatiadae in other streams of Andros is likely.

Habitat and ecology: — Allium stamatiadae grows at wet and shaded localities in the understorey of riparian forests with Platanus orientalis Linnaeus (1753: 999) and Alnus glutinosa ( Linnaeus 1753: 983) Gaertner (1790: 54) , between 550–650 m a.s.l. It usually inhabits stony alluvial deposits by the streams, but often also grows in places with deep soil at stream banks and in crevices of large cliffs deposited within the streambeds. The streams have water flow during the whole year and large part of the A. stamatiadae population is periodically flooded. Rubus sanctus Schreber (1766: 15) , Pteridium aquilinum ( Linnaeus 1753: 1705) Kuhn (1879: 11) , Asplenium scolopendrium Linnaeus (1753: 1079) , Epilobium hirsutum Linnaeus (1753: 347) , and other species of wet habitats, including the endemic Galanthus ikariae Baker (1893: 506) and Scilla andria Speta (1991: 28) , accompany A. stamatiadae in the two known localities.

The population of Allium stamatiadae consists of a few thousand individuals, mainly concentrated in Vourkoti stream. Only a small proportion of the observed individuals produced scapes and also a small proportion of the flowers (up to 10%) produced capsules with seeds. Thus, vegetative reproduction by bulblets seems to be the dominant reproduction mechanism. In some cases, the production of cleistogamous flowers, usually together with few chasmogamous ones, was observed, indicating that autogamy is probably also present.

Karyology: —The somatic chromosome number found in Allium stamatiadae is 2 n = 2x = 16 ( Fig. 3 ). The karyotype is symmetrical, consisting of metacentric (m) chromosomes with no visible satellites. The absence of satellites in the new species differentiates it from its relatives, since Allium orestis (2 n = 2x = 16) has one large satellite on the long arm of a chromosome and one chromosome pair with microsatellites ( Kalpoutzakis et al. 2012), and A. dirphianum Brullo, Guglielmo, Pavone, Salmeri & Terrasi in Brullo et al. (2003: 133) has a tetraploid chromosome complement (2 n = 4x = 32) with at least six microsatellited chromosomes ( Brullo et al. 2003).

Figures

FIGURE 1. Allium stamatiadae – A: individuals with developed spathes similar to leaves; B: bulb with externally inserted scape with bulblets; C: bulb with outer tunics; D: inflorescence; E: unripe capsules; F: flower, apical view; G: inflorescence with cleistogamous flowers. – All photographs by Panayiotis Trigas.

FIGURE 3. Chromosome metaphase plates of Allium stamatiadae from its locus classicus with 2n = 2x = 16 (one chromosome is missing from the left plate). – Scale bar = 10 μm.