Aulacospermum multicaule Pimenov & Tojibaev, 2023

Pimenov, Michael G., Tojibaev, Komiljon Sh., Degtjareva, Galina V., Ostroumova, Tatiana A., Zakharova, Ekaterina A., Karimov, Farkhod I. & Samigullin, Tahir H., 2023, A new species of Aulacospermum (Umbelliferae) from Uzbekistan, Phytotaxa 579 (3), pp. 162-174 : 171-172

Aulacospermum multicaule Pimenov & Tojibaev , sp. nov. ( Figs. 1 , 2A , 3 , 4A , 5 , 7 )

Type :— UZBEKISTAN. Western Tian-Shan , Kurama Range , Chadaksay River Basin , upper reaches of Pashakhansay, locality Betagadik, slopes to the say, between rocks, on fine earth, 07 July 2018, K .Tojibaev, N. Beshko & D.Makhmutzhanov s.n. (holotype TASH, isotype MW) .

Aulacospermum multicaule is similar to A. roseum Korovin but differs from the latter in numerous (up to 11) branched stems, mostly black remains of petioles and sheaths of leaves of the preceding year at rootstock, and petal colour (yellowish vs. white).

Species nostra Aulacospermo roseo Korovin similis, sed plantis caespitosis, caulibus numerosis (usque ad 11), ramosis, reliquiis petiolorum vaginisque foliorum anni praecedentis caudicibus obtectis fere nigris, squamiformibus, membranaceis (non fibrillosis), petalis flavescentibus (non albis) differt.

Erect, multi-stemmed (up to 9‒11), polycarpic perennial. Rootstock branched, with dark brown or almost black, membranous, non-fibrillating remains of last year’s petioles and sheaths of basal leaves. Taproots vertical slightly branched. Stems 18‒42 cm tall, solid, finely grooved, twig-like, 3‒5 mm diameter at base, glabrous, branched almost from the base, with white parenchymal stem core. Leaves predominantly basal, forming dense rosettes or located in the very lower part of stems, with short petioles slightly inflated into narrow sheaths. Leaf blades oblong in outline, 5‒7 cm long, doubly pinnatisect with 2–4 pairs of lateral segments; terminal leaflets lanceolate, with cuneate base, 5‒7 mm long, slightly pointed. Cauline leaves small, glabrous, entire or ternate, sessile, with short narrow sheaths. Petioles glabrous, terete or almost adaxially flattened, with a broad shallow adaxial groove, a small central cavity, with 5 peripheral vascular bundles, 3 peripheral collenchyma bundles and a small collenchyma bundle along the adaxial groove. Umbels sparse, 2‒4.5 cm diameter, 3‒5(6)-rayed, rays unequal, 2‒5(6) cm long, thin, curved. Bracts 1‒3, unequal, linear or linear-lanceolate, early falling. Umbellules compact, 0.5‒1 cm diameter, 3‒5-flowered. Bracteoles 2‒3, short triangular-lanceolate, membranous, with narrow white margin. Pedicels short, nearly equal. Petals yellowish. Mericarps homomorphic, elliptic or ovoid in outline, 4‒5 mm long, 2.5‒3 mm wide, only primary ribs present. Mericarp surface with scattered multicellular tubercles, colliculose, carpophore bifurcated to base; mericarp ribs equal, winged, straight or slightly undulate. Calyx teeth conspicuous, broadly triangular, remaining at fruit, with white membranous margin. Stylopodium low-conical or flat. Styles recurved. Exocarp cells large (40‒50 μm), with convex outer walls. Commissure narrow, exocarp almost reaching carpophore. Mesocarp parenchyma not lignified; vittae thin and solitary in valleculae, two on commissure; rib secretory ducts absent; endosperm on commissural side with a narrow deep groove.

Etymology:— The species epithet refers to numerous branched stems.

Phenology:— The plant was collected with unripe fruits at the beginning of July; most probably, flowering in June, fruiting in July.

Distribution and ecology:— Aulacospermum multicaule is most probably endemic to Uzbekistan ( Fig. 8 ). It grows between rocks on fine earth.

Figures

FIGURE 1. Morphological characters of Aulacospermum multicaule sp. nov. A, flowers; B, umbel; C, stem base.

FIGURE 2. Mericarps in dorsal view. A, Aulacospermum multicaule; B, Aulacospermum anomalum; C, Aulacospermum roseum; D, Pseudotrachydium dichotomum. Scale bar: 1 mm.

FIGURE 3. SEM images of mericarp coat surface of Aulacospermum multicaule. A, general view; B, exocarp of large convex and domeshaped cells, cuticle rugulate; C, multicellular tubercle with a stoma on the top.

FIGURE 4. Schematic transects of mericarps.A, Aulacospermum multicaule; B, Aulacospermum anomalum; C, Aulacospermum roseum; D, Pseudotrachydium dichotomum. 1, Exocarp; 2, Vallecular vittae; 3, Vascular bundle; 4, Mesocarp; 5, Endosperm; 6, Commissure; 7, Destroyed mesocarp cells. Scale bar: 1 mm.

FIGURE 5. Transverse section of petiole of Aulacospermum multicaule. 1, Collenchyma cells; 2, Parenchyma cells; 3, Secretory ducts; 4, Xylem; 5, Phloem; 6, Cavity. Scale bar: 1 mm.

FIGURE 7. Holotype of Aulacospermum multicaule.

FIGURE 8. Type locality of Aulacospermum multicaule in the Kurama Range of the Western Tian-Shan, Uzbekistan.