Additional notes on Ipomoea (Convolvulaceae) in Bolivia

Summary 109 species of Ipomoea L. are recorded from Bolivia. This total includes six new country records and two species, I. prolifera J. R. I. Wood & Scotland and I. inaccessa J. R. I. Wood & Scotland, which are described as new, while I. jujuyensis O’Donell is excluded having been included previously in error. The little-known I. subalata Hassl. is described in full and compared with I. chondrosepala Hallier f. and other species with which it has been confused. The paper is illustrated with line drawings, photographs and distribution maps of the main species discussed.


Introduction
More species of Ipomoea L. are recorded from Bolivia than from any other country in the Americas apart from Mexico and Brazil. 102 species were listed and described by Wood et al. (2015) and the number has now risen to 109 as a result of further field work and herbarium studies. Although there is no easy explanation, the most important factor for this large number appears to be the latitude where Bolivia lies. Both in the northern and the southern hemispheres of the American continent, the greatest diversity in Ipomoea is found between 15 and 25 degrees latitude with diminishing numbers recorded from equatorial regions as well as from the more temperate zones. The diversity of habitats and the presence of several distinct biomes are clearly other factors but are unlikely to be the sole reasons, as some equatorial countries, such as Colombia, have many fewer species of Ipomoea despite their greater size and even more varied habitats.
Since the publication of our account of Ipomoea in Bolivia (Wood et al. 2015), we have had the opportunity to carry out fieldwork in both Bolivia and Paraguay and examine herbarium collections in both these countries and elsewhere. This has resulted in many new records of recognised species and a greater understanding of the characteristics, distribution and conservation status of a number of recently described species, especially I. appendiculata J. R (Wood et al. 2017a) and I. mucronifolia J. R. I. Wood & Scotland in Paraguay (Wood et al. 2017b).
It is now clear that we cited Ipomoea jujuyensis O'Donell in error for I. squamosa Choisy and so I. jujuyensis should be excluded from the list of accepted species for Bolivia. Molecular sequencing of the sole Bolivian collection, Mendoza et al. 2622 showed clearly that it belonged to I. squamosa and this was confirmed by re-examination of the specimen. The absence of I. jujuyensis from Bolivia, however, is odd given its presence in the Andes of Argentina, Peru and Ecuador.
upwards, entire, broadly ovate-elliptic to suborbicular, rounded, base shallowly cordate to truncate, margins undulate; lower leaves 7 -13 × 7 -14 cm, 3 -5-lobed to about halfway (rarely unequally bilobed), the lobes oblong, obtuse to acute, base shallowly cordate; both leaf forms adaxially dark green, pubescent, abaxially grey-tomentose; petioles 2.5 -7.2 cm, pubescent. Inflorescence of pedunculate axillary cymes usually with 7 -8 flowers, mainly near the branch tips, somewhat proliferating; peduncles (0.5 -) 3 -4.5 cm, pubescent, often somewhat bent or twisted, diminishing in length towards apex; bracteoles caducous, not seen; secondary peduncles 0.5 -2 cm; pedicels 13 -20 mm, pubescent, often bent; sepals subequal, 8 -9 × 5 -6 mm, oblongelliptic, densely pubescent, outer rounded with narrow scarious margins, inner rounded or retuse with broader scarious margins; corolla 5.5 -6 cm long, funnel-shaped, pale pink, pubescent, limb c. 4 cm wide; stamens included, short, filaments unequal, 8 -14 mm, glabrous except for hairs at base, anthers c. 3 mm long; style c. 20 mm long, ovary glabrous. Capsule and seeds not seen. Figs 1, 2. RECOGNITION. The pubescent sepals and corolla clearly place this species in a large radiation of mainly South American species of Ipomoea that share these characteristics and this is confirmed by unpublished molecular data. However, the dimorphic leaves are unusual and serve to separate it immediately from species with somewhat similar palmatilobed leaves such as I. CONSERVATION STATUS. This is a narrowly endemic species, known only from a single location, but similar dry bushland covers the hill slopes in the area and it may prove to be more common than is apparent, particularly, if as seems to be the case, it only flowers in years of good rainfall. There is no obvious threat to its habitat, so it should be classified as data deficient (DD) within IUCN guidelines until accurate population studies can be carried out. PHENOLOGY. Found in flower in March but probably continuing to flower into April. This plant was not seen in 2013, a relatively dry year, at the same location and in the same season, so flowering may be very dependent on adequate rainfall. ETYMOLOGY. This species is named Ipomoea prolifera because of its proliferating inflorescences. NOTES. This species is yet another endemic to the hot, dry inter-Andean valley system of the Rio Grande and Rio Mizque. Although we did not find any other endemic species in the immediate vicinity of the two collections, both Liana, 15 -20 m high, the flowers covering the tops of trees; stems, when young green, minutely puberulous, weakly angled; when mature woody, grey, somewhat muricate, glabrescent; rootstock (juvenile) tuberous. Leaves petiolate, 5.5 -14 × 3 -8 cm, ovate, cordate, acuminate, both surfaces minutely and densely puberulent, abaxially paler with rather prominent, raised veins; petioles 2.5 -6 cm, minutely puberulent. Inflorescence of (1 -) 2 -4 (-7)flowered, pedunculate, axillary cymes; peduncles 2.5 -11 cm, minutely puberulent; bracteoles at base of cyme resembling small leaves, upwards caducous, not seen; secondary peduncles 0.5 -4 cm; pedicels 1.5 -3.5 cm, minutely puberulent; sepals slightly unequal, somewhat convex, outer 13 -16 × 10 mm, inner 18 -20 × 15 -18 mm, elliptic to subovate, rounded, rigid, glabrous, pale green with scarious margins; corolla 9 -9.5 cm, funnel-shaped, white with pale pink throat or pure white, glabrous; limb unlobed, c. 6 cm wide; filaments unequal, 15 -24 mm long, anthers 10 mm long; style 3 cm long; stigma biglobose. Capsule subglobose, 18 × 15 mm, glabrous; seeds 8 × 4 mm, pilose on the margins with hairs up to 12 mm long. Figs 3, 4. RECOGNITION. A very vigorous liana reaching heights unattained by most species of Ipomoea. Herbarium specimens are most likely to be confused with I. philomega (Vell.) House but that species has smaller, deep pink corollas, 5 -6 cm in length and, usually, glabrous leaves and distinctive reddish sepals. I. inaccessa has a larger corolla about 9 cm long, which is white or white with a pale pink throat. Its leaves are uniformly densely puberulent on both surfaces and the sepals are pale green. The flower colour and sepal shape suggest it is related to I. reticulata O'Donell and I. saopaulista O'Donell and this is confirmed by unpublished molecular sequence data. However, the much larger dimensions of the sepals (13 -20 mm long, not 7 -10 mm) and corolla (9 -9.5 cm long, not 2.5 -5 cm) rule out both these species. This is a narrowly endemic species, known only from a single area of the Serrania de Bellavista. This is a large ridge, reaching about 2000 m in height, covered in moist hill forest. The habitat is vulnerable but the very steep slopes, the very moist, cloudy climate and its unsuitability for agriculture provide a degree of protection. Careful population studies are needed to assess the extent of populations of Ipomoea inaccessa in the area as the Serrania is extensive and mostly botanically unknown. It can only be treated as Data Deficient (DD) within IUCN guidelines until its populations are carefully studied. PHENOLOGY. Flowering presumably begins in March and continues into May with mature fruit present in July. ETYMOLOGY. This species is named Ipomoea inaccessa because of the difficulties of collecting flowering specimens from high forest on precipitous wooded Andean slopes.
The following species are additional to those recorded for Bolivia by Wood et al. (2015): This species is common in Central America from Mexico southwards but is much less common in South America where it occurs sporadically along the Andes south to Peru and, now, to Bolivia. The only Bolivian collection (N. Salinas 3134 (LPB)) was made in Quime Province in the Department of La Paz between Comunidad Khora and Mikilpirhua at 1900 m. This collection is in fruit but shows the characteristic leaf shape, shortly pedunculate cymes and rostrate capsules typical of this species. Ipomoea peruviana O'Donell (1948: 4). This is known from Peru and Brazil but it was nonetheless surprising that it was found in two distinct localities in Bolivia in 2018, one Puente San Pablo, Marbán in the Beni (Martinez & Adler 83 [LPB,OXF,USZ]) and the other Valle de Sajta, Carrasco in Cochabamba Department (Wood, Martinez & Ledezma 28915 [LPB, USZ]). Both locations are in the humid lowlands in disturbed areas originally covered in rain forest. The flowers are pale lilac in colour as noted by Klug on the label of the type collection and the leaves may be entire or 3-lobed. Fig. 5. Ipomoea volcanensis O'Donell (1953: 398).
This was regarded as an Argentinian endemic before it was collected in Bolivia in 2016. In Bolivia it is known from a single collection (Wood, Hind & Gutiérrez 28059 [K, LPB, OXF, USZ]) from Bosque Tucumano Boliviano at 1446 m on the ridge between Palos Blancos and Entre Rios in Tarija Department. Its occurrence in Bolivia is not unexpected but its discovery makes the absence of Ipomoea jujuyensis more surprising.
Ipomoea subalata Hassl. (Hassler 1911: 157). This is described in full below as it is a very poorly known species and is recorded for Bolivia for the first time: Robust perennial herb reaching 6 m, stems glabrous, usually slightly winged, the wings muricate. Leaves petiolate, 5 -11 × 5 -9 cm, ovate, base broadly cordate to subtruncate, apex shortly acuminate, margin entire to undulate, often denticulate near base, adaxially glabrous, abaxially puberulent especially on the veins, sometimes glabrescent; petioles 3 -10 cm, slightly winged below. Inflorescence of few-flowered, pedunculate, axillary cymes, the flower buds broadly ovoid (Fig. 6B); peduncles often erect, straight, subglabrous, 3 -10 cm; bracteoles minute, lanceolate, caducous; secondary peduncles stout, 2 -8 cm; pedicels 1 -3 cm; sepals subequal, glabrous to very sparsely pubescent, margins scarious, outer sepals 10 -12 × 7 -9 mm, broadly ovate or elliptic, obtuse to rounded; inner sepals 11 -13 × 8 -9 mm, accrescent to 15 mm in fruit, elliptic or suborbicular, rounded to retuse (sometimes mucronulate), with broader scarious margins; corolla 9 -11 cm long, funnel-shaped, pink, pubescent in bud and at tips of midpetaline bands, limb 4 -5 cm diam., weakly lobed; stamens included, slightly unequal, very short, c. 8 -10 mm long, style biglobose. Capsule 15 -16 × 11 -12 mm, ovoid to ellipsoid, very shortly rostrate, glabrous; seeds 6 -11 × 3 -4 mm, pilose on the angles.    Using Geocat (https// www.kew.org/science/projects/geocat) the extent of occupancy of this species within Bolivia is 19,744 km 2 , so it might be treated as Vulnerable (VU) according to IUCN guidelines, but based on its area of occupancy of 56,000 km 2 , it would be categorised as Endangered (EN). The categorisation as Vulnerable (VU) would seem to be more appropriate as the species thrives in disturbed scrub by roads and around "potreros" in areas of dry scrub, where there is little likelihood of significant habitat change, even though its area of occupancy is limited. Globally, this species is difficult to categorise, as the single collection from Paraguay is over a hundred years old. As no search has been made for this species in the area of the type locality, any judgement of its global status is likely to be premature. It might be extinct in Paraguay or, on the  contrary, locally frequent and unthreatened given its predilection for disturbed scrubby habitats. PHENOLOGY. In Bolivia flowering in March and April. NOTES. This species was described from San Luis in northern Paraguay but has never been recollected there.
It has been the source of much misunderstanding by us, as well as by other botanists. In Brazil it has been equated with the plant represented by G. & L. T. Eiten 4077A (K, NY, SP) from Maranhão which we believe is the equally poorly known Ipomoea cearensis O'Donell. More recently in Flora do Brasil 2020 (under construction) the name has been applied to Harley 21983, which is I. pterocaulis J. R. I. Wood & Scotland. In Wood et al. (2015: 59) we equated it with I. megapotamica Choisy, but this was also wrong. I. subalata differs in its larger corolla, longer glabrous sepals and different inflorescence. In our account of Ipomoea in Bolivia (Wood et al. 2015) we mistakenly widened our concept of I. chondrosepala Hallier f. (Wood et al. 2015: 52) to include plants whose corolla was pubescent in bud. We noted that specimens of this species from Paraguay had glabrous corollas and were uneasy about this anomaly at the time, as corolla indumentum is nearly always species-specific in Ipomoea. Our unease increased after observing that some Bolivian collections also had glabrous corollas but it was only after fieldwork in 2017 and 2018 in Paraguay and Bolivia, that we accepted that our concept of I. chondrosepala Hallier f., in fact consisted of two elements, I. chondrosepala itself and the little-known I. subalata.
The five species we know have been confused with Ipomoea subalata can be separated by the following key: 200 and 800 m but prefers slightly disturbed places around tracks or clearings. It is most common in the foothills of the eastern Andean escarpment. Map 3.