Striga musselmanii Omalsree & V.K. Sreenivas, 2018

Moolayil, Omalsree & Sreenivas, V. K., 2018, Striga musselmanii (Orobanchaceae): A new species of Striga from Western Ghats, India, Phytotaxa 375 (1), pp. 99-103 : 99-103

publication ID	https://doi.org/ 10.11646/phytotaxa.375.1.6
persistent identifier	https://treatment.plazi.org/id/49688787-FFAD-ED65-0B92-3A1952A5FE15
treatment provided by	Felipe
scientific name	Striga musselmanii Omalsree & V.K. Sreenivas
status	sp. nov.

Treatment

Striga musselmanii Omalsree & V.K. Sreenivas View in CoL sp. nov. ( Figs. 1 View FIGURE 1 & 2 View FIGURE 2 )

The new species coming under the section Polypleurae , is similar to S. angustifolia by its 15-ribbed calyx lobes, but differs in having glabrous stem, leaf, rachis, bract and bracteole, prominent midrib and lateral veins on leaves, absence of brownish colours in the apex of bract, bracteole and sepals, yellow corolla lobes and tube and stem turned to yellow after drying.

Type:— INDIA. Tamil Nadu: Nilgiri Biosphere Reserve, Naduvattam , 15 September 2016, M. Omalsree 615 (Holotype MH!; Isotypes CATH!, GVCH!) .

Erect annual herbaceous hemiparasites, 16–27 cm tall. Stem branched or unbranched (if branched then from middle to apex), terete at base and angular towards apex, glabrous or nearly so, green, stem turned to yellow after drying. Leaves opposite at base and alternate towards apex, midrib and lateral veins prominent, sessile, 10–28 × 1–3 mm, linear-lanceolate, cuneate at base, margin ciliate with strigose hairs, acute at apex, glabrous on both surfaces. Inflorescence terminal spikes or from axils of upper leaves, 8–14 cm long; rachis angular, glabrous. Flowers zygomorphic, sessile or sub-sessile, hypogynous, loosely arranged, alternate or sub-opposite, 16–29 per inflorescence. Bract single, 2.8–2.9 mm long, linear-lanceolate, margin ciliate, glabrous on both sides. Bracteole 2, 1.7–2.0 mm long, linear-lanceolate, margin ciliate, glabrous on both sides. Calyx tubular, 15-ribbed; ribs distantly arranged and ending upto the teeth; lobes 5, unequal, one lobe is smaller among the others, 2.1–2.8 mm long, linear-lanceolate, margin ciliate, glabrous on both sides, green. Corolla bilabiate; tube 9.4–9.9 mm long, curved above the middle (rarely straight, mostly in bud condition), yellowish, turned to yellow after drying; lobes yellow, 4.2–4.6 mm long, broadly obovate, pubescent without, glabrous within; throat 4.1–4.3 mm long, hairy. Stamens 4, included, didynamous, epipetalous, attached to the distal end of the tube; filaments 1.4–3.2 mm long; anthers 1-celled. Ovary superior, many ovuled, 1.9–2.1 mm long, oblong to ellipsoid, glabrous; style 4.8–4.9 mm long, white, glabrous; stigma brown after drying. Fruit 5.2–5.6 mm long, ellipsoid, apex beaked. Seeds numerous, 0.3–0.4 mm long, ellipsoid with parallel striations.

Flowering & Fruiting:—August–November.

Etymology:—The new species is named in honour of Professor Lytton John Musselman, of Old Dominion University, Virginia, USA for his valuable contribution to the field of plant taxonomy especially on the genus Striga in Africa.

Distribution:—The type locality of the new species is the undisturbed grasslands of Pykara forest regions in Nilgiri Biosphere Reserve.

Host-species specificity:—The new species is parasitic on the roots of Dactyloctenium aegyptium (L.) P. Beauv. (1753: 72; 1812: 10), Digitaria ciliaris (Retz.) Koeler (1786: 16; 1802: 27) and Perotis indica (L.) O. Ktze. (1753: 28; 1891: 787).

Taxonomic Affinity:— Wettstein’s (1895) treated the genus Striga into two sections based on the number of ribs on the calyx tube, viz. S. sect. Pentapleurae with 5-ribbed calyx and S. sect. Polypleurae with 10–15-ribbed calyx. The new species Striga musselmanii , coming under the section Polypleurae because of its 15-ribbed calyx and the plants shows similarities with S. angustifolia (in the same section) based on the number of ribs on the calyx lobes, but differs mainly in having the glabrous nature of the plant and yellow coloured flowers.

SEM information:— SEM studies supported the status of the new species. In S. musselmanii , seeds are ovateelliptic; 370 × 208μM, surface smoothly reticulate. Reticulum lumen with faint trabeculae, without any projecting elements ( Fig. 3A View FIGURE 3 ). Reticulam muri possess triseriate smooth ridges with faint projecting elements. Muri width ranges between 10μM and 35μM. Reticulam lumen appears smooth ( Fig. 3B View FIGURE 3 ) and at the polar ends, the reticulam lumen becomes polygonal in contrast to the elongated reticulam at the equatorial plane ( Fig. 3B View FIGURE 3 ). Hilum inconspicuous. But in S. angustifolia , the seeds linear-obovate; broader at the chalazal end and tapering towards the micropyle 450 × 224μM, surface striate-reticulate, with elongated reticulum. Reticulum lumen laden with triseriate inter connected beads. Reticulum muri possess equal sized biseriate beads and the width ranges between 8 μM and 29μM. The reticulum appears arising from one pole, running through the equatorial plane reaches the other pole. The reticulam arches around the hilum region ( Fig. 3C&D View FIGURE 3 ). Hilum micro-reticulate.

Conservation Status:— The new species is very rare in the locality. We have found only 15-25 plants distributed in two sub populations in a very small area of 1 km 2. The major threat we have expected the regular visit of tourists in these areas. Even though we have no data on past and present population reduction, the conservation status is assessed here as ‘Critically Endangered [CR B1a(iii,iv)+2a(iii,iv); D]’ based on the available data viz. population and population size, number of sub populations and total number of mature individuals, extent of occurrence (restricted geographic range), area of occupancy and locality of the species ( IUCN 2017).

Additional specimens examined (paratypes):— INDIA. Tamil Nadu: Nilgiri Biosphere Reserve, Naduvattam, on the way to Pykara, 15 September 2016, M. Omalsree 613 (MH!).