Prangos multicostata Kljukov & Lyskov, 2016

Lyskov, Dmitry F., Kljuykov, Eugene V., Samigullin, Tahir H., Ukrainskaja, Uliana A. & Khrustaleva, Irina A., 2016, Prangos multicostata (Apiaceae), a new species from eastern Kazakhstan, Phytotaxa 277 (1), pp. 68-76 : 70-75

Prangos multicostata Kljukov & Lyskov , sp. nov. ( Fig. 1 , 2 , 3 )

The new species differs from P. dzhungarica in length of terminal lobes of basal leaves (20–40 mm vs. 5–20 mm), thick umbel rays (1.5–2 mm Ø at base), number of umbel rays (9–12 vs. 12–18), length of umbel rays (7–9 cm vs. 3–4 cm), unequal pedicles in umbellets and thin-grooved stems. It also differs from P. ledebourii Herrnstadt & Heyn (1977: 68) in length of terminal lobes of basal leaves (20–40 mm vs. 5–12 mm), thick umbel rays, presence of secondary ribs, shape of mericarp ribs (thin-winged vs. thin-keeled) and number of mesocarp inner layer parts (five vs. four).

Type:— KAZAKHSTAN. East Kazakhstan Province: Urzhar district, vicinity of Kysyl-Bulak village, Tarbagatai Range ( S side), valley of Kokterek river , gravelly slope, alt.= 830–910 m, 47º 00’ N, 82º 17’ E, 01 June 2010, Maslova & Khrustaleva ( MW, holotype mounted on 2 cross-labelled sheets. Sheet 1—generative part, MW0595558 ; sheet 2—leaf part, MW0595559 ) .

Polycarpic, herbaceous plants with thick taproot 17 mm Ø. Stems 45–60 cm tall and to 6–8 mm Ø at base, single or several, plump, angular, thin-grooved, under umbel slightly ribbed, at base and under umbel scabrous, in upper part glabrous, with branches directed from lower stem part, covered with remains of petioles and sheaths. Basal leaves formed rosette, petioles up to 10 cm long, with narrow sheaths at base, nearly glabrous; leaf blades 25–35 cm long, 18–25 cm wide, triangle or rhombic, 4-pinnate, nearly glabrous; leaf primary segments with petiolulates up to 8 cm long; terminal lobes 2–4 cm long, nearly 1 mm wide, close to filiform, with reflexed down margin, acute. Steam leaves significantly smaller than basal, with narrow sheaths 15–17 mm long, 2-pinnate, with close to filiform leaf lobes 3–4 cm long; terminal umbels 9–10 cm Ø, with 9–12 thickened, glabrous, sometimes unequal rays 7–9 cm long, bracts missing. Umbellets up to 2 cm Ø, 7–10 flowers, pedicels unequal, slightly thickened, 1–2 cm long, terete, glabrous. Bracteoles 4 linear, whole, with white margin. Calyx teeth obscure. Petals virescent, lanceolate, with narrow, long, declinate inside top, up to 2 mm long. Mericarps elliptic or ovate ( Fig. 3 ), 11–16 × 6–11 mm; carpophore bifurcate to base; mericarps homomorphic, slightly dorsally compressed, elliptic, glabrous; primary and secondary ribs presented; all ribs straight, with entire margin, secondary ribs less than primary, primary ribs equal; furrows between ribs narrow, outgrowths absent; stylopods flat or slightly cupped; comissure intermediate, exocarp of small cells; mesocarp divided into an outer “epimesocarp” and inner mesocarp; inner mesocarp divided into 5 parts, which completely separated; “epimesocarp” consisted of parenchymatous, non-lignified cells; inner mesocarp layer consisted of parenchymatous cells with thickened-pore walls; vascular bundles thin, situated in inner mesocarp layer; vittae thin, multiple, near endocarp formed cycle, vallecular and commissural vittae absent; rib secretory ducts absent; endocarp and spermoderma of small cells, hardly separated; endosperm with mushroom-like groove at commissural side.

Additional specimens studied (paratypes): — KAZAKHSTAN. East Kazakhstan Province: Urzhar district, Arkaly Mts., SE side, gravelly slope, alt. = 715 m, 46º 32’ N, 82º 28’ E, 30 May 2002, Maslova & Khrustaleva ( KUZ). Etymology: —The specific epithet refers to the characters of the fruits. Phenology: —It probably blooms in the first half of May, and fruits are mature in June. Distribution: —The species is only known from two localities: East Kazakhstan province, S side of the Tarbagatai Range (Kokterek river valley) and the Arcaly Mountains ( Fig.4). The species forms a dominant community on the debris covered slopes in the middle belt of the mountains.

Taxonomic relationships: —Trees generated for the nrITS and nrETS regions are congruent between themselves and the combined tree. The trees generated by different methods ( MP and BI) possess a similar topology; so we just present a Bayesian tree with the posterior probabilities and bootstrap percentages for the maximum parsimony provided ( Fig. 5 ). In the phylogenetic study P. multicostata was recognised as a distinctive species. It falls into a group with the following species: P. didyma ( Regel 1878: 601) Pimenov & Tikhomirov (1981: 28) , P. cachroides ( Schrenk 1841: 65) Pimenov & Tikhomirov (1981: 28) , P. odontalgica ( Pallas 1778: 34) Herrnstadt & Heyn (1977: 66) , P. trifida ( Miller 1768) Herrnstadt & Heyn (1977: 58) , P. dzhungarica , P. ledebourii and P. herderi ( Regel 1878: 601) Herrnstadt & Heyn (1977: 63) . Most of them, excluding P. odontalgica and P. trifida , are endemic to SE Kazakhstan, Uzbekistan and W China. Prangos odontalgica is distributed in West Kazakhstan and the southern part of the European Russia, and P. trifida is a species with an Ancient Mediterranean distribution. Besides other morphological features, P. multicostata can be distinguished from these species in a carpological character that is diagnostic only in Prangos and related taxa: in the number of inner mesocarp parts. The mesocarp of the Prangos species is divided into two layers: epimesocarp and inner mesocarp. The latter can also be separated into a few parts. The number of such parts depends on the species. Also, P. multicostata is similar in some main morphological characters such as leaf length, leaflet length and shape, number of umbel rays and habitus to the species of the unrelated P. pabularia complex ( Table 2). However, it can be easily distinguished from the latter by the absence of bracts and bracteoles, and the presence of a greater number of short winged ribs. Previously, the presence of secondary ribs on the mericarps was only indicated for unrelated P. ferulacea distributed in SW Asia.

Therefore, after a critical revision of P. pubescens (Pall. ex Schultes 1820: 598) Pimenov & Kljuykov in Kljuykov et al. (2015: 724) and its relatives ( Kljuykov et al. 2015) and this description of a new species, six species of Prangos are known to occur in East Kazakhstan. Four of them, P. herderi , P. dzhungarica , P. pubescens and P. multicostata are endemic or subendemic to this region. Two species, P. ledebouri и P. cachroides , are widespread in Middle Asia. For this reason we regard East Kazakhstan as one of important centres of the species diversity in the genus Prangos .

Figures

FIGURE 1 Prangos multicostata holotype, sheet 1 (MW0595558).

FIGURE 2 Prangos multicostata holotype, sheet 2 (MW0595559).

FIGURE 3 Mericarp cross section of Prangos multicostata. A. primary ribs, B. secondary ribs, C. epimesocarp, D. inner mesocarp, E. vascular bundles, F. secretory ducts. Scale interval = 5 mm.

FIGURE 5 Bayesian phylogenetic tree of nrITS/ETS nucleotide sequences. Posterior probabilities values higher than 0.8 and bootstrap values of MP higher than 70% are shown.