Oropetium almeidanum R.N. Kulloli & R.D. Shinde, 2023

Shinde, Rajendra D., Landge, Shahid Nawaz, Kulloli, R. N. & Chorghe, Alok R., 2023, Oropetium almeidanum (Poaceae: Chloridoideae): a new species from The Thar Desert, Rajasthan, India, Phytotaxa 579 (4), pp. 267-277 : 270-275

Oropetium almeidanum R.N. Kulloli & R.D. Shinde sp. nov. ( Figs. 1 , 2 & 3 )

Type: — INDIA. Rajasthan, Jaisalmer, Near Amarsagar sandstone rocky plateau, N 26.93782 E 70.8875, 18 th October 2021, Chorghe & Kulloli, ACR & RK 0026 (holotype: BLAT; isotype- BSJO; paratypes: BLAT & BSJO) .

Diagnosis: — Spikes disarticulate at maturity into the spiculated segments with which it differs at once from all the species occurring in India. It is allied to Oropetium capense in perennial habit and rhachis circular in transverse section but differs in longer spikelets 4.0–6.0 mm long (vs. spikelets 2.0–3.0 (–4.0) mm long), lower glume long ciliate, a reduced triangular scale (vs. reduced oblong, glabrous), upper glume long-acuminate and nerves strongly ribbed (vs. upper glume acute, nerves not ribbed), palea apex bimucronte (vs. palea apex not bimucronate).

Description

Densely caespitose, short statured perennial grass, 120–140 mm high. Culms slender, terete, 1 or 2 nodded glabrous, geniculately ascending, 3.5–8.0 cm (except inflorescence). Bases invested with laterally flattened, ribbed, glabrous butt-sheaths of which the oldest characteristically disintegrate into fibres. Sheath 5.0–15 × 2.0–7.0 mm long, glabrous, ribbed, vernicose, lower laterally compressed and upper terete; broader at the base and becoming narrow upwards; margin glabrous, sub-hyaline, chartaceous. Ligule membranous-ciliate, 0.2–0.8 mm long. Blade 5.0–8. Jaisalmer 0 × 0.1–2.0 mm, falcately decurved (like a hook), setaceously acuminate, initially flat later conduplicated (0.5 mm in diameter when rolled), thick and extremely narrow, beset with bulbous-based trichomes 0.5–2.0 mm (especially along the margin), slightly curled towards the distal end; multiple of which issuing in a cluster from the bundle like involucre of sheaths at the base of the plant. Inflorescence a solitary unilateral spike, up to 8.0 cm long, sub-terete, only slightly laterally compressed, fragile, transversely disarticulating above each spikelet unit by a sharp horizontal constriction, rhachis strongly ribbed, glabrous, scabrulous. Spikelets: 4.0–6.0 mm long, 1-flowered, bi-seriately disposed on the rhachis, sub-opposite; hermaphrodite, solitary, lodged under the excavated cell of rhachis in a manner upper glume acting as a lid facing away from it and lower glume, if present, placed inside the cavity, awnless, glabrous, strongly ribbed, scabrous without a rhachilla extension. Callus of the floret bearded at the base with long hairs. Lower glume: if present then highly diminished, hyaline-membranous, nerveless, ca. 0.2 mm long, triangular scale-like ciliate (cilia up to 0.5 mm long) organ facing towards the rhachis within the cavity or otherwise completely absent. Upper glume: well developed, 5.5–6.0 × 0.6 mm, coriaceous, linear-acuminate, glabrous, scabrous, 3 nerved (nerves strongly ribbed), bent towards the apex or slightly curled, convex in the lower half of the glume. Lemma: elliptic-lanceolate, 3.0 × 1.0 mm, 2 keeled, margin inflexed throughout the length on broader at the base, 3 nerved, tri-aristate (lateral nerves usually 0.3–0.5 mm long, sometimes not excurrent at all), mid-nerve scabrous excurrent into a fine arista ca. 0.8 mm long, dorsally keeled especially towards the base and the apex, puberulous, scabrous, not bearded at the base. Palea: elliptic, long, 2.5–2.8 mm long, naviculate, hyaline-membranous, 2 nerved (nerves ribbed above the middle on the back), auriculately winged above the middle on the margin, scabrous, glabrous, bearded at the base with white hairs (ca. 0.5–1.1 mm long), bi-mucronate at the apex (ca. 0.3–0.5 mm long). Stamens 3, anthers 0.6–0.8 mm long. Lodicules not seen. Caryopsis fusiform, ca. 1.8 mm long, apex with a persistent bi-mucronate stylar base; embryo almost 1/2 of the caryopsis; hilum punctiform.

Etymology: — The species has been named in honor of Dr. Marselin Rosario Almeida, one of the renowned botanists from India associated to the Blatter Herbarium (BLAT), reminiscing his immense contributions to Indian botany.

Flowering & fruiting: — August–September.

Distribution: — So far only known from Near Amarsagar sand stone rocky plateau and Vinjorai [Binjorai], Jaisalmer district, Rajasthan, North West India. Apparently an endemic grass.

Habitats & associated species: — On the outskirts of Jaisalmer town the habitats are very dried and rocky with extremely low annual rainfall. It grows on exposed sand stone rocky plateaus in Indian desert. It grows in association with Oropetium thomaeum , Melanocenchris jacquemontii Jaubert &Spach (1851: 36) , Tribulus rajasthanensis Bhandari & Sharma (1977: 367) , Leptadenia pyrotechnica (Forsskal 1775: 53) Decaisne (1838: 269) , Ziziphus nummularia (Burman f. 1768: 61) Wight & Arnott (1833: 31) , Dipcadi erythraeum Webb & Berthelot (1848: 341) , Glossonema varians ( Stocks 1851: 863) Bentham ex Hooker f. (1883: 16) , Sericostoma pauciflorum Stocks ex Wight (1848: 15) .

Note: — This is the only Indian species in the genus to exhibit the characteristic of the fracturing spikes. Other unique features are tri-aristate lemma, bi-aristate palea with apical wings, rudimentary lower glume

Additional Specimens Examined (Paratypes): — INDIA. Rajasthan, Vinjorai [Binjorai], Jaisalmer district, s.d., s.coll., s.n. [E. Blatter?] [Barcode: BLAT86687, BLAT!). India, Rajasthan, Jaisalmer, Near Amarsagar sandstone rocky plateau, N 26.937416 E 70.870684, 18 th October 2021, Chorghe & Kulloli ACR & RK 0027 (BSJO!).

Figures

FIGURE 1. Oropetium almeidanum. A. Habit.B. Leaf blade (Adaxial). C. Leaf blade (abaxial). D. Leaf attached with culm. E. Magnified portion of the blade showing marginal hairs. F. Young spike. G. Mature spike. H. Rhachis fracture. I. Spikelet. J, N & O: Lemma. K. Upper glume (inner view). L. Upper glume (outer view). M. Acuminate apex of the glume. P & Q. Palea. R. Stamens. S. Pistil. T. Caryopsis. (Photo plate prepared by R. N. Kulloli)

FIGURE 2. Oropetium almeidanum. A. Habit. B. Spiculated segment. C. Upper glume (dorsal). D. Upper glume (lateral). E. Lemma. F. Palea. G. Anther. H. Caryopsis. (Based on paratype at BLAT). © The Blatter Herbarium (BLAT). (Photography by: Shahid Nawaz)

FIGURE 3. Illustration of Oropetium almeidanum. A. Segment of spike. B. Lower glume. C. Upper glume (dorsal). D. Floret. E. Lemma (inner). F. Palea (inner). G. Caryopsis. H. T.S. of lower glume. I. Anther. (Illustrated by Shahid Nawaz based on the paratype at BLAT).