Isodon delavayi C.L. Xiang & Y.P. Chen, 2014

Isodon delavayi C.L. Xiang & Y.P. Chen View in CoL , sp. nov. ( Figure 1 View FIGURE 1 & Figure 2 View FIGURE 2 )

Isodon delavayi is similar to I. scoparius (C.Y. Wu & H.W. Li 1977: 777) H. Hara (1985: 236) and I. pharicus ( Prain 1891: 297) Murata (1955: 15) , but differs from the former in stems much branched and 15–40 cm long ( vs. 40–100 cm in I. scoparius ), leaves entire ( vs. serrate in I. scoparius ), cymes 1–3-flowered ( vs. 3–5-flowered in I. scoparius ), as well as calyx lobes ovate-triangular ( vs. linear-lanceolate in I. scoparius ) and 1.2 mm long ( vs. 2.5–3 mm in I. scoparius ), from the latter in leaves entire and glabrous ( vs. crenate, glandular puberulent, and puberulent in I. pharicus ), petiole obsolete ( vs. 1–4 mm long in I. pharicus ), and cymes 1–3-flowered ( vs. 3–7-flowered in I. pharicus ).

TYPE: — CHINA. Yunnan: Eryuan County, Menghuoying Village, Mt. Yangyu , elev. 2500 m, 26°11′08.7″N, 100°01′30.2″E, on the open and rocky slope, 21 October 2012, C.L. Xiang, G.X. Hu & Y.P. Chen. 541 ( holotype KUN! GoogleMaps , isotypes K! GoogleMaps , KUN! GoogleMaps , PE! GoogleMaps ).

Shrubs 15–40 cm. Rhizomes woody, 3–7 mm diam., twisted. Stems erect, numerous and much branched, 1–4 mm diam., obtusely 4-angled or subterete; branches gray, glabrescent; branchlets brown to purplish, densely puberulent. Leaves decussate, rarely in whorls of 3; internode (0.3–) 0.5–1 (–2) cm long; lamina ovate-elliptic, narrowly elliptic or lanceolate, 0.5–2 × 0.2–0.6 cm, thick papery, base cuneate to subrounded, margin entire, apex acute, adaxially olive green, abaxially green, both surfaces glabrous and sparsely yellowish glandular, lateral veins 3- or 4- paired; petiole obsolete to ca. 1 mm long. Cymes axillary, 1–3-flowered, densely glandular puberulent and puberulent; peduncle 0.5–1 cm long; floral leaves gradually reduced toward apex, usually shorter than cymes; bracteoles linear, ca. 1 mm long; pedicel 2–3 mm long. Calyx campanulate, ca. 2.5 mm long, purplish, densely glandular puberulent and glandular, yellowish glandular, slightly 2-lipped; lobes subequal, ca. 1/2 as long as calyx, ovate-triangular, lower 2 slightly longer, apex acute; fruiting calyx dilated to ca. 5 mm long, slightly curved. Corolla bluish purple, ca. 7 mm long, puberulent and glandular outside; tube ca. 4 × 2 mm, saccate abaxially near base; 2-lipped, posterior lip 4-cleft, erect, ca. 2.5 mm long, anterior lip entire, concave, navicular, ca. 3 mm long. Stamens 4, base puberulent, included within corolla. Style included, apex 2-cleft. Mericarps brownish, elliptic, ca. 1.5 × 1 mm, glabrous. Fl. Sep–Oct, fr. Oct–Nov.

Leaf epidermis morphology:— Figure 3 View FIGURE 3 demonstrates adaxial ( Figure 3A View FIGURE 3 ) and abaxial surfaces ( Figure 3B View FIGURE 3 ) of leaf of I. delavayi . Both sides are glabrous and sparsely covered with glands. Stomatal apparatuses can only be found in abaxial epidermis and are irregular.

Pollen morphology:— Pollen morphology of the new species is shown in Figures 3C–E View FIGURE 3 . As we can see that pollen grains of I. delavayi are hexacolpate, which is one of the shared characters of subfamily Nepetoideae ( Erdtman 1945, Cantino & Sanders 1986). The ornamentation of exine is bireticulate. Polar axis (P) = 41.9 ± 2.49 µm, equatorial axis (E) = 37.1 ± 2.97 µm. Pollen shape is prolate (P/E = 1.136 ± 0.085).

Mericarp morphology:— Figure 3F View FIGURE 3 shows the shape and size of mericarp of I. delavayi . Length (L) = 1.52 ± 0.087 mm, width (W) = 1.10 ± 0.033 mm. Shape of the mericarp is elliptic. The surface sculpturing is papillate.

Distribution, habitat, and phenology:— According to present collections, I. delavayi is only known from Mt. Yangyu, Eryuan County, Yunnan Province. This rare species grows on open and rocky slopes between 2400 m and 2600 m at elevation. The vegetation in this place is mainly formed by herbaceous and shrubby plants such as Ajania sp. , Cotoneaster sp. , Dracocephalum forrestii W.W. Sm. , Eulalia . sp., Isodon calcicolus (Hand.-Mazz.) H. Hara, Leontopodium sp. , Onosma sp. , and Premna sp. Future fieldwork may expand its distribution area and habitat. Flowering time of I. delavayi is between September and October, and fruiting time from October to November.

Etymology:— The new species is named after its former collector M. I'Abbé Delavay, who was a very famous French missionary and plant collector of the 19th century.

Additional specimens examined ( paratypes): — CHINA. Yunnan: Eryuan County, Menghuoying Village, Mt. Yangyu , elev. 2500 m, 26°11′08.7″N, 100°01′30.2″E, on the open and rocky slope, 21 October 2012, C.L. Xiang, G.X. Hu & Y.P. Chen. 540, 542 ( KUN!) GoogleMaps ; at the same place, 19 October 1887, M. I'Abbé Delavay 2707 ( KUN!) GoogleMaps ; Yunnan: M. I'Abbé Delavay 2922 ( KUN!) .