Distimake rhyncorhiza

Simões, Ana Rita & More, Sushant, 2018, Synopsis and lectotypification of Distimake rhyncorhiza (Dalzell) Simões & Staples (Convolvulaceae): a little known species from the Western Ghats (India), Phytotaxa 336 (3), pp. 293-298 : 294-297

Distimake rhyncorhiza [rhyncorhizus] (Dalzell) Simões & Staples (2017: 575).

Ipomoea rhyncorhiza Dalzell (1851: 179) ; Dalzell & Gibson (1861: 167); Clarke (1883: 214); Woodrow (1898: 172); Talbot (1902:

252). Merremia rhynchorhiza (Dalzell) Hallier f. (1893: 552) ; Cooke (1905: 239); Staples (2010: 500). Type : — INDIA. ‘in montibus Syhadree , prope Tulkut-ghat’ [Talkat] Dalzell s.n. (Lectotype K000830864 !, designated here; isolectotypes:

K000830863!, K000830865!, K001081776!).

Prostrate or trailing herb. Roots tuberous, the tuber sub-woody, moderately rostrate. Stem filiform, glabrous. Leaves cordate in outline, deeply 5–7-palmately lobed, the central lobe acuminate, the lateral lobes with an emarginate, shortly mucronate apex; lamina 4 × 5 cm; margins irregularly dissected; adaxial surface hispid with simple yellowish hairs, abaxial surface glabrous; petiole glabrous, 1–1.5 cm long. Inflorescences of axillary 1–2-flowered cymes; peduncles filiform, glabrous, 5–7 cm long, nearly as long as the leaves, about 4 times longer than the petioles; bracteoles lanceolate, c. 2mm long; pedicels filiform, glabrous, 0.3 cm long. Sepals 5, appressed to the corolla tube, glabrous, unequal, the 2 outer shorter, narrowly elliptic, 1.4 × 0.3 cm, apex shortly acuminate; inner sepals longer, narrowly elliptic, 2 × 0.3 cm, apex shortly acuminate. Corolla funnelform, bright (sulphur-)yellow, 3.5 – 4 cm long, glabrous. Stamens unequal in length, 2 short and 3 long, shortly pubescent at the base of the filaments, yellow; anthers white, spirally twisting at dehiscence; pollen not known. Style filiform, glabrous, white; stigma with 2 globose lobes. Fruit capsular, ellipsoid, 11 × 10 mm, glabrous, 4-valved; sepals strongly reflexed, accrescent in fruit, up to 2 × 0.5 mm; seeds 3 or 4, golden brown, trigonous, 5 mm long, glabrous ( Fig. 1 , Fig. 2 ).

Phenology: —Flowering and fruiting from July to October.

Distribution: —Western Ghats, particularly the southern part, in Maharashtra and Karnataka States. (Map 1). Also reported in the northern part of the Western Ghats, in Gujarat State ( Ranal & Nagar, 2017), but no specimens were located to confirm these reports, although a photograph ( Ranal & Nagar, 2017) appears to be of this species.

Habitat and ecology: —Geophyte ( Gaikwad et al. 2015: 8), growing in rock crevices on lateritic plateaus; also found in open areas on hilly slopes or by the roadside; recorded altitude ranges between 50 and 1,000 m.

Uses: –The tuberous roots and leaves are eaten as vegetables by local people ( Dalzell 1851: 179).

Vernacular name: —“Sada bhaji” [sada = plateau; bhaji = vegetable] (Marathi); “Nhavali” (Marathi).

Conservation status:—Endangered (EN), with a calculated area of occupancy of 20.000 km 2, and extent of occurrence of 1,912.652 km 2 in GEOCAT ( Bachman et al. 2011).

Specimens seen: — INDIA. Maharashtra. Concan: Talkat, ‘in montibus Syhadree, prope Tulkut-ghat’ [Talkat], Dalzell s.n. ( K!) ; ibid., 1 Oct. 2017, More, S. ASSM31 ( BLAT!) ; “Malabar, Concan, etc., regio trop.” Stocks, Law & Co s.n. ( BR!, F, UPS, S). Ghat: Amboli, Chaukul , 16 Sept. 2016, More, S. ASSM30 ( BLAT!) ; ibid., Sept. 1992, Gawade, B. G. 437 ( BLAT!). Karnataka. Belgaum: Kankumbi , 17 Aug. 2008, Shimpale 3342 ( NCK!) ; crevices of rocks at 1,000 m altitude, SUK-SPG 1305 ( SUK) ; Ankola, 30 July 1956, 1.5 miles out towards Kawar, Kapadia, Z. J. ZK2158 ( BLAT!) ; ibid., Kapadia, Z. J. ZK2159 ( BLAT!) ; ibid., Kapadia, Z. J. ZK2162 ( BLAT!) ; ibid., Kapadia, Z. J. ZK2163 ( BLAT!) ; ibid., Kapadia, Z. J. ZK2164 ( BLAT!). North Kanara: Hattikeri , Oct. 1919, Hallberg & McCann 34405 ( BLAT!) ; ibid., Hallberg & McCann 34422 ( BLAT!) ; without locality, Almeida MRA2573 (BLAT!).

Typification: —The lectotype was selected because the sheet is annotated by Dalzell in his own handwriting and is the most complete specimen with flowers and, most crucially, the presence of the beak-shaped root that is characteristic of the species. We have also taken the opportunity to correct two orthographic mistakes related to the gender and spelling of the epithet: when making the combination in Distimake ( Simões & Staples 2017: 571) , the epithet was incorrectly changed to the masculine form and wrongly spelled ‘rhynchorrhizus’ (sic). The epithet is a noun used in apposition as treated by ICBN (Art. 60.8) so should not be modified.

Discussion:— The four-valved chartaceous capsule with enlarged, strongly reflexed fruiting sepals is characteristic of the genus Distimake so confirming the placement of D. rhynchorhiza in this genus. As no other similar species has been found anywhere in the genus and, given the high frequency of endemism in its area of occurrence, we are satisfied that this is a distinct species endemic to the Western Ghats. Although all the distinctive characters occur in other species in the genus, they never occur in the same unique combination. The bright yellow corolla is not common in the genus, but a few species of Distimake from the Neotropics do have this colour. D. rhynchorhiza exhibits a specialized ecological preference for lateritic rock outcrops, which could explain its rarity and restricted distribution. It is probable that the species also occurs in Gujarat, although no voucher specimens confirm this. Efforts are needed to confirm its presence there with any consequent revision to the assessment of its conservation status.

MAP 1. Distribution of Distimake rhyncorhiza (Dalzell) Simões & Staples.

Figures

FIGURE 1. Distimake rhynchorhiza (Dalzell) Simões & Staples. A. Habit. B. Flower, side view. C. Corolla, upper view. D. Calyx. E. Gynoecium and androecium (voucher ASSM 30, BLAT) F.Fruit. G. Seeds (voucher MoreASSM31 (BLAT); H.Amboli:habitat in an open rocky lateritic plateau; collection site of More ASSM30 (BLAT);. Photographs: © Sushant More, 2016 & 2017.

FIGURE 2. Distimake rhynchorhiza (Dalzell) Simões & Staples. A. Habit. B. Leaf. C. Flower, side view. D. Corolla, front view. E. Root. F. Stigma. G. Anther. H. Fruit. I. Seed. Drawn by Priyanka Ambavane.