Oropetium almeidanum (Poaceae: Chloridoideae): a new species from The Thar Desert, Rajasthan, India Author Shinde, Rajendra D. St. Xavier’s College (Autonomous) Mumbai 400001 Author Landge, Shahid Nawaz The Blatter Herbarium (BLAT), St. Xavier’s College (Autonomous) Mumbai 400001 Author Kulloli, R. N. Arid Forest Research Institute (AFRI, Jodhpur- 342005, Rajasthan, India Author Chorghe, Alok R. Rajiv Gandhi Regional Museum of Natural History, Sawai Madhopur- 322001, Rajasthan, India text Phytotaxa 2023 2023-01-24 579 4 267 277 http://dx.doi.org/10.11646/phytotaxa.579.4.4 journal article 10.11646/phytotaxa.579.4.4 1179-3163 7563980 Key to the species of Oropetium in the world 1. Rhachis fragile, readily or tardily disarticulating into spiculated segments (African & Arabian species; exceptionally including O. almeidanum ) ......................................................................................................................................................................................2 1. Rhachis not fragile, not disarticulating into spiculated segments, apparently tough and persisting ( Indian species )........................5 2. Annual; butt sheaths lacking at the base of the culm ...................................................................................................... O. aristatum 2. Perennial; butt sheaths persistent at the base of the culm ..................................................................................................................3 3. Spikes straight or curved, never flexuous; rhachis bilaterally flattened not triangular in transverse section, spikelets in two subopposite rows; upper glume apex acute or long-acuminate (apex 2.5 mm long), never awned ........................................................4 3. Spikes straight or flexuous; rhachis not bilaterally flattened, triangular in the transverse section, spikelets in two rows disposed just side by side (adjacent); upper glume apex acuminate to long awned (awn 2–18 mm long)........................................... O. minimum 4. Spikelets 2.0–3.0 (–4.0) mm long; upper glume nerves not ribbed, apex acute; lemma 1.5–2.0 (–2.5) mm long; palea apex without excurrent keel nerves; caryopsis 1.0– 1.5 mm long ............................................................................................................ O. capense 4. Spikelets 4.0–6.0 mm long; upper glume 4.0–5.3 × 0.8 mm , nerves strongly ribbed, apex long-acuminate; palea apex with two conspicuous excurrent keel nerves and broadly winged; caryopsis up to 1.8 mm long............................................. O. almeidanum 5. Annual; spikes 1.0– 3.5 cm long; one flowered spikelet without a rachilla extension .......................................................................6 5. Perennial; spikes more than 4.0 cm long; usually one flowered, sometimes also two flowered spikelet then with a conspicuous rachilla extension................................................................................................................................................... O. roxburghianum 6. Butt sheaths absent at the base of the culms; spikes terete, not with a distinct saw-toothed appearance, up to 1.5 cm long, subtended by a spathaceous sheath at the base; lemma villous on the dorsal side......................................................................... O. villosulum 6. Butt sheaths persistent, somewhat fibrous at the base of the culms; spikes laterally compressed, with a distinct saw-toothed appearance, 1.5–3.5 cm long, not subtended by a spathaceous sheath at the base; lemma glabrous on the dorsal side...................... ....................................................................................................................................................................................... O. thomaeum