Ipomoea attenuata J.R.I.Wood & Scotland, 2017

Wood, John R. I., Munoz-Rodriguez, Pablo, Degen, Rosa & Scotland, Robert W., 2017, New species of Ipomoea (Convolvulaceae) from South America, PhytoKeys 88, pp. 1-38 : 3-5

Ipomoea attenuata J.R.I.Wood & Scotland sp. nov. Figure 1

Diagnosis.

Ipomoea attenuata has been generally treated in herbaria as I. campestris because of the similar leaves and the pubescent exterior of the corolla, but is readily distinguished by the distinctive ovate sepals, 11-14 mm long, with truncate base and long attenuate apex. Additionally, the inflorescence is of elongate complex cymes, somewhat racemose in form and with distinctive persistent linear-lanceolate bracteoles. This contrasts with I. campestris , which has oblong-ovate, acute sepals 8-11 mm long, clearly narrowed to the base. The inflorescence of I. campestris is short, usually less than 5 cm long, and consists of shortly pedunculate cymes, these often reduced to single flowers, the bracteoles caducous (Table 1 ).

Type.

BRAZIL. Distrito Federal, Loc. Gama, BR 60, ca. 8.2 km do Tevo , DF-180 SO, disturbed campo sujo, dispersed locally, 15.5756°S 48.1059°W, 1030 m, 26 Feb. 2015, M. Mendoza, J.B.A. Brugel, A.A. Santos, T. Reis & T.K.M. Arquelão 4802 (holotype UB, isotypes CEN, K) .

Description.

Perennial herb; rootstock a woody xylopodium; stems up to 80 cm long, 2 mm diam., decumbent, weakly ascending or, fide field notes, climbing, pubescent with relatively long, often twisted, spreading and appressed hairs. Leaves shortly petiolate, 4-10 × 0.3-0.7 cm, narrowly oblong, entire, apex acute and shortly mucronate, base cuneate, both surfaces thinly pubescent but more densely so abaxi ally; petioles 3-7 mm long, pubescent. Inflorescence of lax, compounded axillary cymes from the middle and upper leaf axils; cymes up to 15 cm long, rather narrow, diminishing in size upwards, irregularly racemose in form; peduncle 2-7 cm long, often extending into a rhachis, pubescent; primary bracteoles foliose, 9-12 × 1-3 mm, linear, acuminate, persistent; secondary peduncles 0.5-2 cm long, thinly pubescent; ultimate bracteoles 4-7 × 0.5-1 mm, linear-lanceolate, finely acuminate to attenuate, persistent; pedicels very short, 3-5 mm long, a few scattered hairs present; calyx ovate in outline; sepals subequal, 11-14 × 4-5 mm, ovate with distinct truncate base and long-attenuated acuminate apex, glabrous, the inner sepals very slightly longer than outer; corolla funnel-shaped, pink or reddish-purple, 4-5 cm long, pubescent on the midpetaline bands, limb c. 2.5-3 cm diam., shallowly lobed; stamens glabrous except at the base, unequal, longer 1.7-1.8 cm, shorter c. 1 cm, anthers linear, c. 3 mm long; ovary bilocular, glabrous; style glabrous, stigma bilobed. Capsule 13-15 × 8 mm, ovoid, glabrous; seeds 7 × 3.5 mm, ellipsoid, blackish-brown, glabrous except for pubescence along the angles.

Distribution and habitat.

BRAZIL. Endemic to the Distrito Federal and Goiás State, where it appears to be a rare species of cerrado. Figure 2 .

Additional collections seen.

Goiás: Samambaia, Rio Corumbá, E.P. Heringer 11283 (NY). Goiás: Mun. Luziania, Santo Antonio do Descoberto, R.C. Mendonça 93 (IBGE, NY). Goiás: Serra dos Pireneus, c. 20 km S of Corumbá de Goiás, H.S. Irwin et al. 11019 (NY).

Conservation status.

This species has been found in four separate locations. Two of the four collections are of apparent unicates and the only collection for which any details are available is the type. The field notes of this collection describe the plant as dispersed in campo sujo. Ipomoea attenuata is, therefore, apparently rare but relatively widely distributed. (Fig. 2 ). It has an area of occupancy of approximately 16.000 km², thus indicating Endangered status (EN) within IUCN guidelines (2012) but should probably be treated as Data Deficient (DD) until the populations of this species can be carefully evaluated.

Etymology.

The epithet " attenuata " refers to the attenuate tips of the sepals and bracteoles.

Notes.

Although we have not been able to sequence this species, I. attenuata probably belongs to a large clade of around 70 species almost restricted to South America, which is characterised morphologically by the pubescent exterior of the corolla and the subequal, pubescent, ovate herbaceous sepals. However, the attenuate sepal tips raise doubts about this tentative placement as this shape is atypical of species in this clade.

The form of the inflorescence (axillary cymes) combined with the oblong leaf shape strongly suggests this is essentially a decumbent species even though this is not indicated in field notes.

Figures

Figure 1. Ipomoea attenuata A habit B xylopodium C section of stem showing indumentum D sepals outermost (left) to innermost (right) E corolla opened out to show stamens F ovary and style G capsule H seed. Drawn by Rosemary Wise A-E from H. S. Irwin et al. 11019 F-H from M. Mendoza et al. 4802.

Figure 2. Map of Eastern Brazil and Paraguay showing distribution of Ipomoea attenuata (▲), I. dasycarpa (■) and I. dolichopoda (✖).