Ochradenus lakhpatensis Patel RM & Prajapati SR, 2024

Patel, Rohitkumar M., Prajapati, Sujitkumar R. & Martín-Bravo, Santiago, 2024, Ochradenus lakhpatensis (Resedaceae), a new species from Gujarat, India, Phytotaxa 633 (1), pp. 92-100 : 94-98

Ochradenus lakhpatensis Patel RM & Prajapati SR , sp. nov. ( Figs. 2–4 )

Diagnosis:― O. lakhpatensis is morphologically similar to O. harsusiticus from which it differs by the pedicellate flowers (pedicels 1.5–2 mm) and fruits (pedicels 2–3 mm) (vs (sub-)sessile flowers and fruits in O. harsusiticus ), a higher number of stamens (15–18 vs c. 12), longer sepals (2–2.5 mm vs 1.5–2 mm), wider fruits (7.5–8.5 mm vs (4–) 5–6 mm) and open fruit apex (vs closed) ( Table 1). In addition, O. lakhpatensis is easily distinguished from all other Ochradenus species, other than O. harsusiticus , by its low bushy spreading habit, distinctive gnarled (knobbly, rough, and twisted, especially with age) and woody base and branches, rosulate clusters of spathulate leaves, and fruits strongly 3-lobed in transversal section, gaping at the apex.

Type:― INDIA. Gujarat, Kachchh district, Lakhpat taluka, Umarsar 23°45’32.81’’N, 68°49’42.85’’E, 53 m, 22 January 2023, Rohitkumar Patel & Sujitkumar Prajapati 0967 (holotype: CAL; isotypes: BSJO, CAL) .

Additional material examined (paratypes):― INDIA. Gujarat, Kachchh district, Lakhpat taluka: Near Guneri village , 23°47’53.84’’N, 68°47’50.02’’E, 41 m, 24 February 2008, Rohitkumar Patel 0135 ( GUIDE, Bhuj) ; Fulra-Dhareshi Road , 23°42’30.64’’N, 68°49’29.98’’E, 66 m, 16 January 2022, Rohitkumar Patel & Sujitkumar Prajapati 0823 ( GUIDE, Bhuj) ; Naliya-Narayan Sarovar road, 23°35’15.49’’N, 68°36’54.72’’E, 74 m, 14 March 2021, Rohitkumar Patel & Sujitkumar Prajapati 0615 ( GUIDE, Bhuj) ; Baranda , 23°31’46.45’’N, 68°40’55.63’’E, 100 m, 10 April 2015, Rohitkumar Patel & Sujitkumar Prajapati 0313 ( GUIDE, Bhuj) .

Morphological description:― Habit intricately branched, gnarled, low bushy spreading shrub up to 50 cm tall. Stems repeatedly branching in all directions, glabrous, divaricate, branchlets spine-tipped after drying of apex, the bark of young branches green, turning mustard yellow when mature, more or less flaking when old, longitudinally ruggedly ribbed when dry. Leaves present almost throughout the year, on young and old (except dried) branches, in alternate, both solitary and rosulate arrangements, often on short c. 1–2 mm branchlets, entire, sessile, fleshy, obovate to spathulate, 3–20 (–30) × 1–1.5 (–3) mm, wrinkled when dry. Inflorescence a terminal spine-tipped raceme, 4–15 flowered, loosely arranged, up to 6 cm. Flowers hermaphrodite, c. 5 mm wide, on 1.5–2 mm pedicels, subtended by a foliaceous bract, c. 1–2 mm. Sepals 6 (–7), elliptic to obovate, 2–2.5 × 1–1.3 mm, incurved, brown when young, turning green when mature. Disc fleshy, orange-brownish to greenish-yellow, with a wavy margin, eccentrically surrounding the ovary, often raised centrally to form a collar-like rim around filaments. Petals 6, ephemeral and early deciduous, limb c. 2 mm long, white, linear with 1 or 2 basal teeth, sometimes lobed. Stamens 15–18, orange turning yellow at maturity, filaments c. 2 mm, anthers oblong, 1–1.2 mm. Ovary with 3 carpels, each topped with a stigmatic tooth, unilocular, parietal placentation, wall glabrous. Fruit a capsule, strongly 3-lobed in transversal section, ovoid, more or less as long as broad, 8–9 × 7.5–8.5 mm, straw-coloured when mature, walls membranaceous, brittle, apex open, on 2–3 mm pedicel, indehiscent. Seeds reniform, 1.5–1.6 × 1–1.2 mm, testa minutely tessellate, more or less shiny, blackish brown when mature.

Distribution:― Endemic to the Indian state of Gujarat, known from five localities in the Kachchh district, Lakhpat taluka ( Fig. 1 ).

Habitat and associates:― O. lakhpatensis grow in arid, open scrub vegetation on moderate to gently undulated terrain, gravelly substratum with sodic laterite soil, associated with Aristida adscensionis L. (1753:82), Cymbopogon iwarancusa (Jones ex Roxb.) Schult. (1824:458) , Dactyloctenium scindicum Boiss. (1859:131) , Dodonaea viscosa Jacq. (1760:19) , Euphorbia caducifolia Haines (1914:154) , Indigofera cordifolia B. Heyne ex Roth (1821:357) , Schoenoplectus sp. and Taverniera cuneifolia (Roth) Arn. (1836:332) .

Phenology:― November to April (flowering and fruiting).

Conservation Assessment:― The species is known so far only from five populations from a relatively restricted area (Kachchh district, Lakhpat taluka; Fig. 1 ), which implies that species range descriptors EOO and AOO are limited to 247.59 km 2 and 20.00 km 2, respectively. A total of approximately 1860 individuals have been censused, ranging between less than 50 (Fulra-Dhareshi road and Baranda populations) to more than 1500 (Umarsar population), where the species is locally common. However, the species faces severe threats affecting the area, extent and/or quality of the habitat due to coal and limestone mining, wind turbine installation and road construction. Therefore, O. lakhpatensis is tentatively assessed here as “Endangered” [EN B1ab(iii)+2ab(iii)].

Etymology:― The specific epithet is derived from the name of the taluka (a local unit of administrative division), where the type locality and all the known populations of O. lakhpatensis are located (Lakhpat taluka, Kachchh district, Gujarat state, India).

Identification key for the herein accepted species of Ochradenus (modified from Abdallah, 1967; Miller 1984; Martín-Bravo & Amini Rad, 2010)

1. Fruit oblong-ovoid to ellipsoid, at least 1.5 as long as broad; fruit pedicels 2–5 mm; stamens up to 80 ..........................................2

- Fruit globose or ovoid-globose, less than 1.5 as long as broad; fruit pedicels 0–3 mm; stamens up to 18 .......................................4

2. Stamens 12–14; racemes up to 5 cm long; branches whitish or pale brown, with surface flaking on older branches; leaves solitary and in fascicles .......................................................................................................... O. randonioides Abdallah [ Somalia, Ethiopia]

- Stamens 17–80; racemes up to 40 cm long; branches green or yellowish green, with surface wrinkled on older branches; leaves solitary ................................................................................................................................................................................................3

3. Seeds with tuberculate-papillose, dull testa; stamens c. 25; inflorescence glabrous to glandular-pubescent, lax to dense................. ............................................................................ O. spartioides (O.Schwartz) Abdallah [ Yemen, Oman; including O. gifrii Thulin ]

- Seeds with smooth, glossy testa; stamens up to 80; inflorescence glabrous, lax ................................................................................. .......................................... O. aucheri Boiss. [SE Arabian Peninsula, Iran, S Pakistan; including O. ochradenii (Boiss.) Abdallah ]

4. Ripe fruit baccate (with fleshy walls), white or reddish when dry; shrub with frequently struggling habit; seeds with minutely papillose testa .......................................................... O. baccatus Delile [NE Africa, SW Asia; including O. socotranus A.G. Mill. ]

- Ripe fruit papery, yellow or straw-coloured; shrub with spinescent habit; seeds with smooth or minutely tessellate testa..............5

5. Leaves linear; fruit round in transverse section....... O. arabicus Chaudhary, Hillc. & A.G. Mill. [C, S Arabian Peninsula, SE Iran]

- Leaves narrowly elliptic to spathulate; fruit clearly lobed in transverse section ...............................................................................6

6. Flower pedicel 1.5–2 mm, up to 3 mm in fruit; stamens 15–18; fruit 7.5–8.5 mm wide, with apex gaping ....................................... .......................................................................................................................... O. lakhpatensis Patel RM & Prajapati SR [W India]

- Flower and fruits (sub-)sessile; stamens c. 12; fruit (4–) 5–6 mm wide, with apex closed ........... O. harsusiticus A.G.Mill. [ Oman]

Figures

FIGURE 1. Distribution map of O. lakhpatensis sp. nov., indicating location in India, Gujarat and Kachchh district with detailed satellite view depicting the known populations within the Lakhpat taluka.

FIGURE 2. Ochradenus lakhpatensis sp. nov.: Habitat (above) and habit (below).

FIGURE 3. Morphological details of Ochradenus lakhpatensis sp. nov.: A & B. flowering and fruiting twigs, C. flower, D. calyx and disc (other flower parts were removed), E. ovary with disc and pedicel (other flower parts were removed), F. transversal cut of the ovary showing parietal placentation of ovules, G. mature dry fruit with pedicel, H. seeds.

FIGURE 4. Ochradenus lakhpatensis sp. nov.: A. different leaves representing the variability of shape and size, B. flowering twigs with pollinators (honeybees and ants), C. top view of mature fruit (note the 3-lobed section and open apex), D. different stages of fruit ripening.