Vincetoxicum luridum Stocks ex S.A. Shah, 2018

Shah, Sayed A., Sultan, Amir, Wen, Jun, Nisa, Surat U., Su, Xu, Iqbal, Javed & Mumtaz, Abdul S., 2018, Vincetoxicum luridum (Asclepiadeae, Asclepiadoideae, Apocynaceae), a new and long misunderstood endemic species from Balochistan, Pakistan, Phytotaxa 357 (2), pp. 117-125 : 123-124

Vincetoxicum luridum Stocks ex S.A. Shah , sp. nov. ( Figs. 1–3 )

Type: — PAKISTAN. Balochistan: “ Baluchistan ”, 3500–5500 feet, [1849], [Stocks] 721 (Holotype K! [ K 001235295], isotypes: K! [ K 001235294], [ K 001235296]).

Diagnosis:— Similar to V. stocksii but differs in lurid appearance, denser indumentum, ovate corona lobes, shorter follicles, seeds with dense brown spots on dorsal surface and narrow cylindrical caudicles ( Table 1).

Herb to undershrub, up to 80 cm tall, lurid, stem longitudinally striate, densely pubescent, internodes 2.4–6.4 cm long, rarely shorter. Leaves decussate, lower and upper leaves smaller than the middle ones, petiolate; petiole adaxially channeled, pubescent, 2–6 (7) mm long; lamina lanceolate to narrowly ovate, sometimes elliptic-lanceolate, densely pubescent on both sides, 3–6 × 1–2 cm, margins smooth, mostly ciliate, apex acute to narrowly acute, base mostly obtuse to sometimes sub-acute, veins visible on both surfaces, sometimes sunken or only midrib prominent, moderately pubescent or glabrous after seed dispersal. Inflorescence axillary, mostly both sessile and pedunculate inflorescences present on the same plant, sometimes only sessile inflorescence present, peduncle up to 2.5 cm, rarely longer and branched. Flowers pedicellate, pedicel 3–5 mm long, mostly apically pubescent, up to 12 linear bracts present at the bases, ca. 1 mm long. Sepals ovate or tapering to the acute to obtuse apex, ca. 1 mm long, a few hairs present on margins or abaxially. Colleters 5 per flower, one in each sinus of the calyx lobes, narrowly ovate, ca. 0.5 mm long. Corolla purple, lighter in color than the inner parts, tube ca. 1 mm long, lobes oblong-ovate with a emarginate apex, 2 × 1 mm, pilose within, corona ovate, 1 × 0.5–0.7 mm, longer than gynostegium, convergent, staminal appendages obtuse with a short stalk. Pedicel in fruit up to 8 mm long; follicles lanceolate, 5–6 × 1 cm, glabrous, inconspicuously striated, apex shortly acuminate, seeds margined throughout except at apex, 8–10 × 5–7.5 mm, marginal wings up to 1 mm broad, dorsal surface densely red spotted, coma ca. 1.5 cm long.

Notes:—three duplicates of Stocks 721 which were used by Wight (1850: 1614) for his illustration of V. arnottianum are housed by K. Two of them have Stocks’ name as collector. The third specimen that we designate here as the holotype has a manuscript note (in Stocks’ handwriting) “ figured by Wight in his Icones from my specimens as his Vincetoxicum arnottianum I doubt ”. The three duplicates are labeled V. luridum . This name was not published hence, Ali & Khatoon (1982) indicated it as a nomen nudum. Therefore, we prefer to validate the name instead of giving a new name because the specific epithet “ luridum ” means lurid appearance, which is the diagnostic character of the new taxon.

Specimens examined:— PAKISTAN. Balochistan: 8 km from RCD highway on Khuzdar Nal road, 05 October 1990 A. Ghafoor & S. M. Goodman 29804 ( KUH!) ; ca. 4 km from Surab on road to Kalat, RCD highway, Sandy Loam with gravel, 11 May 1990, A. Ghafoor & S. M. Goodman 5092 ( KUH!) ; 15 km from Khuzdar on way to Kalat , 22 March 1996, G. R. Sarwar, S. Omer & M. Qaiser 373 ( KUH!) ; ca. 85 km from Khuzdar city on way to Kalat, in Apple and Apricot garden, ± 1460 m, 27 May 1995, T. Ali & G. R. Sarwar 2550 ( KUH!) ; About 50 miles from Nushki on way to Quetta , 13 October 1971 M. Qaiser & A. Ghafoor 4385 ( KUH) ; ca. 30 Km from Kalat on road to Surab , sand-clay soil with stones, 24 October 1986, A. Ghafoor & S. Omer 2202 ( KUH!) ; ca. 20 km from Gurdgab on way to Naushki , 6 May 1985, A. Ghafoor & R. Yusuf 1355 B ( KUH!) ; about 20 miles from Khuzdar on way to Surab , 5 June 1970, M. Qaiser & A. Ghafoor 1212 ( KUH!) ; b/w Panjgur & Ghichk, Makran Div. 6 April 1988, T. Ali 1010 ( KUH!) ; Rest House Nag , corona purple, 5 April 1971, S. Abedin & A. Hussain 6844 ( KUH!) ; ca. 6 miles from Wadh on way to stream bed, sandy soil, CA. 70 cm, 5 June 1970, M. Qaiser & A. Ghafoor 1179 ( KUH!) ; B. Khuzdar & Kalat (Surab), 1200 M, 1 May 1998, M. Shah 61 ( PMNH!) ; Krechi, Nag, Panjgur , Balochistan, 20 April 1998, S. Nadeem 12 ( RAW!) ; Kalat , 24 km S. Sorab, 28°29’N, 66°19’E, K. H. Rechinger 27383 ( K!) ; Common in Baluchistan above 3000 feet, Stocks , 1849, 721 ( B & C: isotypes) ( K!) ; Khuzdar Division: along Khuzdar-Nal Road, 8 km from Khuzdar turnoff, coarse alluvial soil, 27º46’N X 66º32’E, 10 May 1990, A. Ghafoor and S. M. Goodman 5018 ( GH!) ; Kalat Road, Khuzdar , ± 4000 ft., 17.04.1979 M. Shah & N. Isan 108510 ( ISL!) .

Figures

FIGURE 1. Palynology of Vincetoxicum arnottianum complex. (A) & (B) V. luridum, photographed from S. A. Shah 23 (RAW!); (C) & (D) V. stocksii, photographed from J. Lamond 1440 (MO!); (E) & (F) V. arnottianum, photographed from M. Shah 489 (ISL!); (G) & (H) V. sakesarense, photographed from I. Ahmad 27821 (RAW!) & H. Jahan 1125 (ISL!) respectively.

FIGURE 2. SEM of leaf and seeds of V.luridum and V.stocksii. (A) & (B)Adaxial and abaxial surfaces of V.luridum respectively showing dense trichomes, photographed from SAS 23 (RAW!); (C) & (D) adaxial and abaxial surface of V. stocksii respectively, photographed from A. H. Khan s.n. (RAW!); (E) & (F) dorsal and ventral views of V. luridum respectively, photographed from T. Ali & G. R. Sarwar 2550 (KUH!); (G) & (H) dorsal and ventral views of V. stocksii respectively, photographed from Shariq 8322 (PFI!). P=Pores, Td= Threads, Tm= Trichomes

FIGURE 3. Geographic distribution of Vincetoxicum arnottianum complex. The map is based on field and herbarium data, and generated in ArcMap 10.2.