Semenovia gyirongensis Q.Y.Xiao & X.J.He, 2017

Xiao, Qun Ying, Tan, Jin Bo, Hu, Hao Yu, Zhou, Song Dong & He, Xing Jin, 2017, Semenovia gyirongensis (Apiaceae), a new species from Xizang, China, PhytoKeys 82, pp. 57-72 : 58-59

Semenovia gyirongensis Q.Y.Xiao & X.J.He sp. nov. Figure 1 , 2A1-A6 , 4 , Suppl. material 1: Fig. S1A-B, S3

Type.

China: Xizang, Gyirong County, Woma village, near Longda , 28°45.01'N, 85°18.22'E, 4023 m, 30 July 2016, xqy - 20160730 - 01 (holotype SZ; isotypes SZ) .

Diagnosis.

Semenovia gyirongensis is most similar to S. malcolmii , but can be easily distinguished by its roots (cylindric much-branched vs. fusiform unbranched), caudex (intensively branching, long, underground, with distinct nodes vs. unbranched to much-branched, short, overground or emergent, without distinct nodes), terminal leaf lobes (narrowly ovate to ovate vs. linear to narrowly long-ovate), and bracts (oblong, apex obtuse-rounded or cuneate vs. linear to narrowly ovate, apex acute).

It is also similar to the closely related species S. pamirica , but differs in stems (simple or sparingly branched vs. much dichotomously branched), rays (5-10 vs. 2-4), and commissural vittae length (reaching 1/4 mericarp length vs. reaching 3/4 mericarp length).

Description.

Herbs perennial, polycarpic, grayish-green, 8-38 cm high, very dense ribbon shaped hairs throughout, with intensively branching long (up to 40 cm) underground caudex having distinct nodes (rooting at the nodes). Root long, cylindric, much-branched. Stems simple or sparingly branched, rigid, at the base covered with straw-yellow rigid imbricate perished leaf sheaths and petioles. Basal leaves rosulate, 5-21 cm long, numerous, very dense hairs on both sides; petioles (3-15 cm) longer than or nearly equal to blades; sheaths narrowly long-ovate, lavender; blades linear or narrowly-ovate in outline, 2-3-pinnate, primary pinnae 5-8 pairs; terminal leaf lobes (0.5-2 mm, narrowly ovate to ovate). Low cauline leaves similar to basal leaves but smaller, with narrowly long-ovate sheaths; middle-upper cauline leaves gradually reduced, sessile, with soft ovate sheaths. Compound umbels with 4-10 rays (1-2 cm, sub-equal length), slightly thickened in fruit. Central umbels broader than lateral umbels, up to 3.5 cm in diameter, compact. Bracts 2-5 (minute, 0.4-1.5 mm), oblong, apex obtuse-rounded or cuneate, caducous. Umbellets 0.8-1.8 cm in diameter in fruit, 6-15 flowered; bracteoles 4-6, purplish green, narrowly long-ovate, 2-4 mm; calyx teeth small, narrowly ovate. Petals broadly obovate or narrowly ovate, adaxially whitish-yellow, abaxially purplish-yellow, puberulent on both sides, outer flowers of the umbel radiant with outer petals enlarged, unequally emaginate at the tip, with narrow lobule bent inwards. Stylopods short-conic, wavy at the margin, yellow-green, 0.3-0.5 × 0.65-0.9 mm; styles reflexed, 2-3 mm long. Fruits with slender carpophore, bifurcate to the base; mericarps strongly dorsally compressed, elliptic or broadly elliptic in outline, 4-7 × 2-5 mm, on dorsal surface densely covered by thin hairs. Dorsal ribs filiform and marginal ribs narrowly-winged (0.2-0.5 mm broad). Vittae filiform, 4 on dorsal surface (1/2-3/4 length mericarp), 2 on commissure surface (short, about 1/4 as long as mericarp).

Fruit anatomy. Exocarp is formed by one layer of small cells. Outer mesocarp layer is of thin-walled parenchyma cells; inner mesocarp (hypendocarp) is consisted of thick-walled lignified fibrous cells. Five ridges are found on each mericarp. Vascular bundles are thin in dorsal ridges, broad in marginal ridges and commissural side. There are 4 dorsally and 2 ventrally vittae. Endoderm is located as one line under the vittae and seems to be integrated with the spermoderm. The seed is composed of endosperm and spermoderm with a thickened cell wall (Suppl. material 1: Fig. S3).

Pollen morphology. The pollen grains are isopolar symmetric, the aperture is tricolporate type. The pollen shape is prolate with an ellipsoidal equatorial outline, the polar ends are rounded and the ornamentation is cerebroid. Polar axis (P) = 26.53 ± 0.85 µm, equatorial axils (E) = 13.43 ± 0.9 µm (n = 20) (Fig. 1O-Q and Fig. 2A6 ).

Phenology. The species was found flowering in July-September, fruiting in August-October.

Distribution and habitat.

S. gyirongensis is only known from the type locality, China, Xizang, Gyirong County, Woma village, near Longda (Suppl. material 1: Fig. S2). It grows on screes, rocky slopes and sandy places, at elevations between 4000 and 4150 m.

Etymology.

The specific epithet is derived from the type locality, Gyirong County in Xizang, China.

Conservation status. S. gyirongensis is hitherto known only from Gyirong County (the type locality) where it usually grows on screes, rocky slopes and sandy places, locally common. In field investigation, we found that the area is subjected to overgrazing pressure and only a handful of individuals can escape from eating or trampling, ultimately blossoming and fruiting. Because of its localized distribution and grazing pressure, it should be assessed as “Vulnerable” (VU) according to the IUCN (2016).

Additional specimens examined

(paratypes). China: Xizang, Gyirong County, near Longda , 5 July 1975, Z. Y. Wu et al. 75-0676 (barcode: KUN0565801!, PE 00756653!, PE 00756650! and HNWP 53717!) .

Figures

Figure 1. Semenovia gyirongensis A-B Habitat C Abaxial surface of primary pinnae D Basal leaf sheaths E Middle-upper cauline leaf sheaths F Rays G Adaxial surface of primary pinnae, showing hairs H Compound umbel I Umbellule J Bracts K Calyx teeth and stylopod L Infructescence M Dorsal side of mericarp N Commissural side of mericarp O Cerebroid ornamentation on equatorial plane of pollen grain P Tricolporate Q Rounded pollen polar ends.

Figure 2. Diagnostic morphological characters of Semenovia gyirongensis (A 1 - A 6) in comparison to the similar species Semenovia malcolmii (B 1 - B 6) A 1 - B 1 Habitat A 2 Oblong minute bracts, apex obtuse-rounded or cuneate B 2 linear to narrowly ovate bracts, apex acute A 3 narrowly ovate to ovate ultimate leaf lobes B 3 linear to narrowly long-ovate ultimate leaf lobes A 4 Long-branched underground caudex with distinct nodes B 4 Short-branched overground or emergent caudex A 5 Cylindric and much-branched root B 5 Fusiform and unbranched root A 6 Ellipsoidal pollen grains B 6 Equatorially constricted pollen grains.

Figure 4. Illustrations of Semenovia gyirongensis (from the holotype) A Habit B Basal leaf C Compound umbel D Flower E Dorsal surface of mericarp F Commissural surface of mericarp.