Asparagaceae Juss.

Burkart, Michael, Kavula, Kened Alfred, Constantine, Immaculate Kileo, Mollel, Neduvoto Piniel, Piniely, Luciana Naftal, Sikawa, Robert Augustino & Yinger, Barry R., 2025, Sansevieria bangalalana sp. nov. (Asparagales, Asparagaceae), close to extinction in the wild, and five other narrowly endemic and threatened species of Sansevieria from Tanzania, European Journal of Taxonomy 1026, pp. 65-106 : 67-102

Family Asparagaceae Juss.

Sansevieria currently encompasses three subgenera, i.e., subgen. Capitulatus Mbugua ex L.E.Newton & R.H.Webb (14 spp.), subgen. Paniculatus Mbugua ex L.E.Newton & R.H.Webb (13 spp.), and subgen. Sansevieria (75 spp.). The classification is based on inflorescence architecture. However, molecular-based phylogenies ( Takawira-Nyenya et al. 2018; van Kleinwee et al. 2022) do not fully support this taxonomic concept based on morphology.

Sansevieria bangalalana Mollel, M.Burkart, Sikawa & Yinger sp. nov. urn:lsid:ipni.org:names:77370777-1

Figs 1–6

Diagnosis

Sansevieria bangalalana sp. nov. is the only species of Sansevieria known presently that has capitate inflorescences and long, straight, bifacial (ʻflatʼ) but strongly inrolled leaves ( Figs2, 3A). The colouration of the flowers includes reddish brown, yellowish and greenish parts, which is also unique in the whole genus ( Fig. 4B). The flower tubes are only 25 mm long, much shorter than in any other species of the subgenus Capitulatus , to which this species belongs according to its inflorescence type.

Etymology

Sansevieria bangalalana sp. nov. is named for Bangalala Ward, where this species was found.

Type material

TANZANIA • Kilimanjaro Region, Same District, foothills of the North Pare Mountains; 896 m a.s.l.; 14 Dec. 2021; B. Yinger & R.A. Sikawa YS 1026; on a strip of flat gently sloping land between a gravel road and a seasonal stream, probably inundated during the heaviest rains in season, growing together with extensive populations of Sansevieria volkensii Gürke , S. fischeri (Baker ex Dyer) Marais and scattered small trees, in an extremely arid area with a short rainy season; holotype: NHT [000001159].

Living specimens ex typo cultivated at TSF and POTSD.

Description

Rhizomatous herb, stemless, vegetative height ca 1 m, 1–2 leaves per shoot, forming loose clumps ( Figs 2, 3B). Rhizome subterranean but close to soil surface (ca 0–10 cm), rhizome diameter ca 38 mm, inner cortex of mature rhizome†† light brown. Leaves upright, strongly folded longitudinally ( Fig. 3A), very stiff, straight, blue green, slightly mottled, linear outline, to 1 m long or slightly longer, 60 mm wide, leaf base 73 mm wide, 19 mm thick, leaf adaxial surface forming a rounded to pentagonal channel from base to tip 7 mm deep at mid-leaf, adaxial surface slightly rough with light-dark pattern in transverse bands, margin pale orange (orange white 159 grp A), 1 mm long awn tip; leaf abaxial (= outer) surface with very numerous stomata sunk into the surface, with short to medium-long, nodose, straight to wavy, largely unconnected transverse ribs between them ( Fig. 5). Inflorescence ( Figs 3B, 4) on fully leaved shoot, capitate, axis 185 mm long overall, peduncle 93 mm long, 13 mm in diameter, grayed yellow, bearing 6 dry bracts ca 23 mm long, flower-bearing axis 92 mm long, flower-head 87 mm in diameter excluding anthers and styles, very dense with 3–4 flowers per partial inflorescence, bracts of partial inflorescences 7–15 mm long, 2–5 mm wide, herbaceous, lanceolate, without extrafloral nectaries. Flowers on pedicels ca 6 mm long, yellow green, without articulation; corolla tube light reddish brown, tip of buds green, proximal parts of lobes yellowish outside, bright white inside; overall flower length 36 mm, tube 25 mm long, lobes 11 mm long, 2 mm wide, diameter of closed flower shortly before anthesis 3 mm at the base, 2 mm at the narrowest point, 3 mm in the upper part, lobes strongly curling back at full anthesis (more than 360°); filaments white, 18 mm long, filiform, anthers 2–3 mm long; style straight, white, 47 mm long excluding ovary including stigma, 22 mm exserted from tube mouth, stigma translucent, 1 mm wide; ovary yellowish green, ovoid. Fruits and seeds unknown. Youth form (young shoots from leaf cutting) different from adult plant, leaf transect openly u-shaped, colouration fresh green with transversally oriented, whitish patterning; cataphylls similarly green but largely unpatterned ( Fig. 3C).

Ecology and distribution

Sansevieria bangalalana sp. nov. was only found at the type location, on a strip of flat gently sloping land between a gravel road and a seasonal stream, probably inundated during the heaviest rains in season, growing in dry bushland with small trees and extensive colonies of Sansevieria volkensii Gürke and S. fischeri (Baker ex Dyer) Marais.

Taxonomic remarks

Sansevieria bangalalana sp. nov. is unique in the combination of several features. There is no other species of Sansevieria known presently that has capitate inflorescences and long, straight, bifacial (ʻflatʼ) but strongly inrolled leaves. The leaf surface is outstanding and the colouration of the flowers is also unique, although difficult to describe, including reddish brown, yellowish and greenish parts. Figure 4 gives an appropriate impression. Last, the flower tubes are only 25 mm long, which is extremely short for a capitate-flowered species.

From a distance, however, S. bangalalana sp. nov. is hard to distinguish from S. fischeri and large forms of S. volkensii which both are encountered regularly in the same region.

Tentative threat assessment

Critically endangered: CR B2ab(iii); C1+2(i); D.

Sansevieria bangalalana sp. nov. was first observed by us (RAS, BRY) on December 14, 2021, when a sterile living specimen was collected ( YS 1026). At that time, a strip of flat land between the Bangalala Road and the foothills of the North Pare Mountains was covered with extensive colonies of Sansevieria volkensii , S. fischeri , and colonies of another taxon, probably S. bangalalana . This site is about 100 m wide and 3 km long. Because of the variability of S. volkensii and S. fischeri , it was not clear whether or not we were seeing something new. Only when YS 1026 flowered at TSF in early March, 2022, it became clear that it is a unique new species.

On several visits to the site (October and November, 2023, and January, 2025) we found that almost the entire area possibly occupied by S. bangalalana sp. nov. had been cleared of all vegetation, its remnants burned, and the whole site scraped to bare soil. On October 27, 2023, we observed 22 leaves in a heavily stressed colony at roadside, mostly covered with soil ( Fig. 6), of which only four survived to January, 2025, so regarding the morphology of S. bangalalana there were fewer than 4 shoots remaining on few square meters in a very unfavourable situation. On this last visit, a second colony of about 25 plants including one inflorescence was found in another location. There is now very little natural vegetation remaining anywhere between the main highway and the town of Bangalala, as most of it has been converted to agricultural land. There is virtually no chance that any other plants of S. bangalalana will remain there.

In conclusion, S. bangalalana sp. nov. is imminently threatened by extinction in the wild. IUCN threat category CR (critically endangered) applies under criteria B2 (AOO < 10 km ²), C1 (less than 250 mature individuals and strong population decline), C2i (<50 mature individuals in both subpopulations), and D (<50 mature individuals overall). Additionally, we suppose that the probability of extinction in the wild within 10 years is> 50% (criterion E). Apart from the plants in cultivation at TSF, POTSD, and one other collection, only one small stand (ca 25 shoots) and the four leaves by the road and largely covered with piled soil are left. The present threat status according to our data is CR, close to EW.

Sansevieria chlorantha M.Burkart, Kavula, Sikawa & Yinger sp. nov. urn:lsid:ipni.org:names:77370778-1 Figs 1, 7–9; Table 1

Diagnosis

Sansevieria chlorantha sp. nov. is characterised by its short but rather thick brownish rhizomes, its numerous, long, narrow, rather thick and clearly patterned leaves, its long inflorescence with medium-sized, greenish flowers, the colour extending to the style and filaments, its conspicuous, long-living bracts of the partial inflorescences, its styles that are distinctly longer than the filaments, and its grass-like flower odour. The greenish colouration of filaments and style, or parts of them, is very unusual in the genus.

Etymology

Sansevieria chlorantha sp. nov. was named for the largely green flower colour, including parts of the filaments and style.

Type material

TANZANIA • Kilimanjaro Region, remnant of natural vegetation within a village; 810 m a.s.l.; 17 Mar. 2020; B. Yinger & R.A. Sikawa YS 0350; holotype: NHT [000001155] .

Living specimens ex typo cultivated at TSF and POTSD.

Description

Acaulescent herb, rhizomatous, stemless, vegetative height around 1 m, ca 6 leaves per shoot, longest leaf at intermediate position, forming dense stands ( Fig. 7A). Rhizome to 150 mm long, rhizome diameter 35–50 mm, inner rhizome cortex brownish. Leaves dispersed in all directions, upright to spreading, very stiff, up to 1 m long or a little bit longer, to 62 mm wide, strap-like, without petiole but with a median ridge on the abaxial side, lamina u-shaped to somewhat v-shaped and thickened to 42 mm in central part††, slightly rough on the adaxial and clearly but finely rough on the abaxial surface, dull dark green, whitish dotted and transversely banded, darker colour covering ca 60–70% of leaf adaxial surface but only ca 50% of abaxial surface, pattern not fading with leaf age, margin red-brown and whitish, with ca 8 dark longitudinal lines from base to tip adaxially and ca 15 abaxially, leaf base to 63 mm wide, awn-like tip to 74 mm long, leathery. Inflorescence ( Fig. 7) unbranched elongate, central on fully leaved shoot, up to 1.35 m long, peduncle to 0.5 m long, green, 14 mm in diameter between the two lowermost bracts, patterned with tiny dots and lines, with three peduncle bracts to 175 mm long and two hypsophylls (intermediate basal leaflets bigger than the bracts but much smaller than the leaves) below them, bracts light green with purple dots; flowering part 0.85 m long, flowers arranged densely to lax, subverticillately, 6 (5–7) flowers per partial inflorescence but fewer in the upper part, lower bracts of partial inflorescences to 55 mm long and 14 mm wide, central and upper ca 13–17 mm long and 4–5 mm wide, triangular to lanceolate, not dry at anthesis. Flowers medium-sized, on articulate pedicels 9–12(14) mm long, basal part 6–9 mm, distal part‡‡ ca 3 mm, light green, corolla outside coloured light green as well, without longitudinal lines, wilting flowers not changing colour substantially, basal diameter ca 3 mm but only ca 2 mm on narrowest part, tubes ca 25 mm long, lobes ca 18 mm long and ca 2 mm wide, curling back at anthesis to 360°, filaments greenish, thread-like (not substantially flattened or widened), ca 16 mm long, anthers closed ca 4 mm long, opened ca 3 mm long, yellow green, style white to greenish, straight, ca 54 mm long above ovary, ca 31 mm exserted from flower throat (i.e., greatly exceeding the filaments), stigma ca 1 mm wide, translucent, ovary ovoid, yellow green; flowers open from evening to early morning; flower odour: fresh grass. Fruits# glossy and slightly warty when unripe, orange and almost smooth when ripe ( Fig. 8A). Seeds# globular to elliptical, 5.5–7.3 mm long, 4.4–5.5(6.7) mm thick, yellowish or light brown (colour dimorphic), hilum lateral, large, circular to elliptical, diameter 3.5–5.3 mm, brighter than the light brown seed surface ( Fig. 8B–C).

Ecology and distribution

Sansevieria chlorantha sp. nov. was found only once in a village occupying a strip of remaining natural vegetation on gently sloping land. Downslope, where there are soils suitable for field crops, the land is now entirely converted to agriculture. Until recently, these plants were growing in the shade of a strip of native trees remaining before the village expanded. Nearly all of these trees were removed when the road was widened. Upslope are extensive populations of S. volkensii . This is a very arid area with stiff infertile soil in the Kilimanjaro Province, North Pare Mountains region ( Fig. 1).

Taxonomic remarks

Sansevieria chlorantha sp. nov. (subgenus Sansevieria ) has similarities to S. enchiridiofolia R.H.Webb & L.E.Newton which also seems to have conspicuous, long-lasting, greenish bracts of partial inflorescences (see Webb & Newton 2019: fig. 7) and rather thick, narrow leaves of similar, dark green colouration and patterning. Sansevieria enchiridiofolia , however, is clearly different due to its mostly single-leaved shoots, sweetly-scented flowers that are white instead of greenish, and longer styles. It is also a rare species, occurring more to the north in Tanzania, north of Arusha, and possibly also in adjacent Kenya ( Webb & Newton 2019; MB pers. obs.). Also, S. lunatifolia L.E.Newton from S Kenya has similarities in the leaf dimensions and cross-section ( Newton 2015). However, it has rougher and thinner leaves and the flower traits are different including scent, colouration and filament length. This species is also rare. The more frequent S. rugosifolia R.H.Webb & L.E.Newton has much shorter but wider leaves of different colouration and further differences in inflorescence and flower features. Table 1 gives an overview.

Sansevieria chlorantha sp. nov. was tentatively named S. viridiflora in Yinger & Sikawa (2023c).

Tentative threat assessment

Critically endangered: CR B2ab(v); C1; E.

We only know one certain population of S. chlorantha sp. nov. which is at the type location. In March 2020, there were more than 200 shoots, but the population in September 2023 was only about 100 shoots, i.e., a reduction by 50% in less than 4 years and one generation ( Fig. 9). Since then, it has further declined (last visit in January, 2025). According to IUCN criteria B2 (AOO < 10 km ², only 1 location known and continuing decline observed in number of mature individuals) and C1 (population decline of more than 25% in 1 generation), we rate this species as Critically Endangered (CR) according to our data. As the location is in an intensely developed area where land is at a premium for housing and small businesses, extinction in the wild might happen soon (criterion E, probability of extinction in the wild>50% within 3 generations).

Sansevieria embere Mollel, M.Burkart, Yinger & Sikawa sp. nov. urn:lsid:ipni.org:names:77370779-1 Figs 1, 10–15; Table 2

Diagnosis

Sansevieria embere sp. nov. is characterised by its very long and dense, spear-like inflorescence, with 7 large sterile bracts on the peduncle, extraordinarily long-tubed flowers in partial inflorescences of only up to 3 flowers which have straight styles and anther and style exsertion of rather similar length.

Etymology

ʻEmbereʼ is a maasai word for a spear, recalling the form of the inflorescence. The place where S. embere sp. nov. was found would have been the home of Maasai.

Type material

TANZANIA • City of Arusha, Arumeru, Manyara Estate ; 1448 m a.s.l.; 24 Aug. 2020; B. Yinger & R.A. Sikawa YS 0641; holotype: NHT [000001156] .

Living specimens ex typo cultivated at TSF and POTSD.

Description

Acaulescent herb, rhizomatous, vegetative height ca 1 m, 2 cataphylls and 2–4 leaves per shoot, pointing to all directions, longest leaf at intermediate position (neither outermost nor innermost) on individual shoots ( Fig. 10); fresh cataphylls purple, mottled. Rhizome subterranean but close to soil surface (ca 0–10 cm), runners to 0.2 m long, rhizome diameter ca 30–50 mm, colour of inner rhizome cortex light ochre, fresh rhizome outside view yellowish, older light brown, young cortex very thin (ca 0.2 mm), thicker when old (ca 1 mm). Leaves upright to spreading, stiff, up to 1 m long or slightly longer, 94–120(142) mm wide, central lamina 5 mm thick, flat to slightly u-shaped, lanceolate, clearly narrowed to the base but without petiole, abaxial side with insignificant central ridge, leaf base ca 50–70 mm wide and 10 mm thick, margin red-brown and whitish, often somewhat undulate, distal part narrowed to a leathery tip 2–8 mm long; adaxial surface smooth, medium to blackish green in older leaves but with bluish bloom when young, with more than 20 dark longitudinal lines from base to tip, somewhat insignificantly patterned with lighter green dots and bands in zig zag patterns, strongly glossy in cultivation but much less so in the wild ( Fig. 11); abaxial surface with punctiform elevations in a rather loose pattern, thereby finely though clearly rough to the touch, dull to silky glossy with up to 40 dark green continuous or interrupted longitudinal lines, much more clearly patterned than adaxial side; patterning of the leaves fading with age but still visible in old leaves. Inflorescence ( Fig. 12) of very conspicuous length, elongate thyrsoid, terminal on fully leaved shoot, axis 1172 mm long overall, peduncle 446 mm long, 15 mm in diameter, yellowish at the base to dark green upwards, patterned with tiny dots and lines, bearing 7 dry bracts to 281 mm long, flowering part 726 mm long, flowering inflorescence 73 mm in diameter excluding anthers and styles, dense, 1–3 flowers per partial inflorescence at the lower part, 3– 5(8)†† at the median and 1–2 at the upper part; bracts of partial inflorescences 12–21 mm long, 2–4 mm wide, herbaceous (not dry during anthesis), lanceolate, without extrafloral nectaries. Flowers on dark green, sometimes purple pedicels 5 mm long, articulated close to the receptaculum, corolla outside coloured yellowish to greenish, tube 67 mm long, lobes 31 mm long, 2 mm wide, overall flower length 98 mm, diameter of closed flower‡‡ shortly before anthesis 3.5 mm at the base, 1–1.4 mm at the narrowest point, 3 mm in the upper part; lobes strongly curling back at full anthesis ( Fig. 12B); anthers yellowish to greenish, anthers ca 4 mm long, filaments filiform, 47 mm long, styles straight, 110 mm long above ovary, 47 mm exserted from tube mouth; ovary light green to yellowish, cylindric, apex truncate. Flowers opening in the evening, wilting in the afternoon. Fruits# small to medium-sized, surface glossy when unripe, covered with numerous rather large whitish dots, slightly rugose and orange when ripe, in all stages with several but small verrucae ( Fig. 13). Seeds ( Fig. 14) elliptical, 6–7.3 mm long, 5.7–6.7 mm thick, light brown, with dull surface, hilum apical, elliptical, rather large, ca 5.3 mm diameter, brighter than the seed. Youth form (seedlings) slightly different from adult plant, leaf colouration lighter green with transversally oriented, whitish patterning ( Fig. 15).

Phenology

The flowers open in the evening as in most species of Sansevieria , but last until the following afternoon, i.e., uncommonly long.

Ecology and distribution

Sansevieria embere sp. nov. has so far been found only in a pocket of succulent vegetation in Arusha City within extensive coffee plantations ( Figs 1, 10). It is likely that this species was restricted to the area now occupied by the city and its once-vast coffee plantations, which are monocultures of coffee and Grevillea robusta A.Cunn. ex R.Br. This area is not especially arid, with long rainy seasons and occasional rains off-season. The soil is fertile and well-drained.

Taxonomic remarks

Seeds were studied from fruits collected from ca 45 individual infructescences all over the population at the type location with one fruit per shoot.

This iconic species in the subgenus Sansevieria is similar to S. raffillii N.E.Br. in overall size, leaf dimensions and posture, inflorescence size, and greenish flower colouration. It differs from this species, however, in having more leaves per shoot, darker leaf colour, leaves that are finely rough rather than smooth on the abaxial side, much longer peduncle bracts, and fewer flowers per partial inflorescence. Also, the pedicel relationships are different. Most striking, however, is the difference in flower tube length. Actually, S. embere sp. nov. is the species with the longest flower tube among all red-bordered flat-leaved species of Sansevieria with the exception of S. pedicellata la Croix , a plant from the border region of Mozambique and Zimbabwe, which is clearly different in many features ( Rulkens & Baptista 2009; la Croix 2010; Table 2). The next in flower size in this group, S. newtoniana T.G.Forrest occurring in Uganda and adjacent N of Tanzania ( Forrest 2014; Yinger & Sikawa 2021e), is different from S. embere in leaf colouration and stiffness as well as in inflorescence and flower features. An overview is given in Table 2.

Several accessions similar to YS 0641 have been identified in the TSF living collection. None of these, however, has flower tubes longer than 30 mm, and several differ in other traits as well. They belong to other species, therefore, some of which possibly are undescribed yet.

Tentative threat assessment

Critically endangered: CR E.

Residual fragments of Sansevieria populations are not uncommon in and around Arusha, but there does not seem to be another one of this species. At least, we could not find any during numerous excursions. It appears that the survival of this particular colony is intentional although no one lives nearby.

There is only this single population known, with very limited spatial extent (less than 10 m × 100 m) and limited although conspicuous size, and without any legal conservation status, on privately-owned but publicly accessible land. We suppose that the probability of this single population to become extinguished is> 50% in 3 generations as it occurs within the Arusha City limits (IUCN criterion E), classifying it as CR according to our data.

Sansevieria muhaensis M.Burkart, Yinger, Sikawa & Mollel sp. nov. urn:lsid:ipni.org:names:77370780-1 Figs 1, 16–19, Table 3

Diagnosis

Sansevieria muhaensis sp. nov. is characterised by its undulate leaf margins ( Fig. 16), its very long, greenish bracts of partial inflorescences in the flowering head ( Fig. 17) and the dark red colouration of the inner rhizome cortex. It is somewhat similar to S. kirkii Baker which also has a median ridge on the leaf abaxial side and similar flower dimensions. In S. kirkii , however, the abaxial leaf ridge is more pronounced and bears several lateral furrows from base to leaf tip which are completely lacking in S. muhaensis . Also, S. muhaensis has longer runners and a dark red rather than dark brown colouration of the inner rhizome cortex which is characteristic of S. kirkii . Further, the outside corolla pattern of S. kirkii is reddish to dark red, not grey as in S. muhaensis . An overview is given in Table 3.

Etymology

Sansevieria muhaensis sp. nov. is named for the Muha, the tribe associated with the area where this species was found.

Type material

TANZANIA • Kigoma Region, near the limits of Kigoma City ; 803 m a.s.l.; 3 Mar. 2020; B. Yinger & R.A. Sikawa YS 0279; on termite mounds in sun; holotype: NHT [000001160] .

Living specimens ex typo cultivated at TSF and POTSD.

Description

Acaulescent herb, rhizomatous, stemless, vegetative height†† ca 720 mm, 2 green cataphylls and 3–6 leaves per shoot forming a regular rosette ( Figs 16, 18), longest leaf at intermediate position (neither outermost nor innermost) on individual shoots. Rhizome to 250 mm long, diameter ca 36–46 mm, inner cortex colour†† deep red. Leaves up to 900 mm long or slightly longer, to 85 mm wide, lingulatelanceolate, without petiole, moderately falcate to slightly twisted, with a median ridge on the abaxial side and more or less undulate margins (more so in wild-growing plants, Fig. 16), openly u-shaped and thickened, both surfaces smooth with silk gloss, patterned with cloudy blotches anywhere and cloudy transverse bands on some leaves, mostly in their middle and lower parts, the lighter colour covering ca 50% on both surfaces but appears stronger on the abaxial side, strongest on new leaves, with a few dark longitudinal lines on the adaxial side only which do not extend to the leaf tip, lamina central thickness ca 16 mm; leaf base ca 85 mm wide, ca 26 mm thick, margin lined reddish-brown and whitish, awn-like tip to 38 mm long, brown, stiff and almost sharp on new leaves, leathery and flexible on old leaves. Inflorescence terminal on fully-leaved shoot, capitate ( Fig. 18C), ca 350 mm long overall, peduncle ca 290 mm long, 18 mm in diameter, medium green with purplish flecks or spots all over but white-pinkish at the base,

S. sinus-simiorum S. bhitalae S. kirkii S. sumbawangana S. rukwana S. muhaensis sp. nov. sp. nov. sp. nov.

leaves per shoot 8–10 (?) 1(2–3) 1–3 / 2–88 2–5 2–3 3–6

rhizome diameter [mm] 50 50§ 20–42| 70

30 36–46

inner colour of rhizome cortex ochre‡‡ dark brown| brownish orange leaf posture erect to slightly erect ascending-spreading to upright to spreading recurved recurved‡

dark reddish orange deep red spreading to almost spreading horizontal leaf length [mm] to 1000 750 (400–900); 1000– 750–2750 1000

2000††

leaf width [mm] 60 50–70 60–90(to 120|) 210

max. lamina thickness in central 50 (massive) 8–14‡ 20

part of leaf [mm]

pseudo-petiole missing missing| existing‡ missing lamina transect massively u-shaped massively u-shaped| concave or flattish‡ openly u-shaped to almost flat leaf margin rather straight rather straight| very wavy‡ somewhat wavy median ridge on leaf abaxial side (massive) (massive) strong| missing leaf colour pattern inconspicuous to yellow-green mottling mottled or transversely almost missing present from prominent to very banded faint state of flowering shoot often lateral, bearing only fully-leaved fully-leaved cataphylls and bracts†

peduncle length (base to lowermost 290 ca 300 to ca 500 300

pedicel) [mm]

peduncle diameter [mm] 15 15 13‡/15| 20

peduncle bracts 6 “3 pairs”§ 5–6‡ 7

peduncle bracts length [mm] 32–35 30/60 50–77‡ to 78

(“Superclone”)§

810

110

6

missing flat but u-shaped sinuate missing adaxial cloudy, abaxial transverse bands fully-leaved

163

20

4

46–114

900

85

16

missing openly u-shaped, thickened undulate existing cloudy blotches and transverse bands fully-leaved

290

18

8

to 116

patterned with tiny dots and lines, with 8 peduncle bracts to 116 mm long but without hypsophylls, the lowermost with elongate tips, the upper only short-tipped, bases always shell-like, pale greenish with a few to many small dark dots when young, enveloping the flower-head in its first developmental stages, but dry at anthesis; flower-bearing part ca 60 mm long, with 4 flowers per partial inflorescence throughout the inflorescence; bracts of partial inflorescences 42– 33 mm long, 9– 5 mm wide, with 8–3 nerves, pale green when young but dry at anthesis, lanceolate, rather shortly tapering to a short sharp point, without nectaries. Flowers with aromatic odour; pedicels inarticulate, ca 9 mm long, light green; corolla outside coloured greyish before anthesis with greenish tips, with short greyish longitudinal lines on the basal part of the lobes in bud stage, wilting yellowish; tube ca 117 mm long, lobes ca 36 mm long, ca 3 mm wide, curling back at anthesis to 360°; filaments whitish-yellowish, ca 32 mm long, thread-like, open anthers ca 5 mm long, yellowish; style white, straight, ca 155 mm long above ovary, exserted ca 39 mm, stigma translucent-yellowish, ca 1 mm in diameter, ovary ovoid, light green. Fruits and seeds are unknown to us.

Ecology and distribution

Sansevieria muhaensis sp. nov. YS 0279 was collected in the NE part of Kigoma City in Kigoma Region, near the city limits ( Figs 1, 16). There are a number of collections from this area that are probably the same species as YS 0279, but they have not flowered yet. Based on several extended visits to the region, RAS and BRY guess that S. muhaensis was common in the area based on what can still be seen where fragments of nature persist. YS 0279 was found on termite mounds on school grounds. The other collections which are likely to be the same species all were also found growing on termite mounds. The plants remaining are growing in sun or light shade, but it is likely that all were originally growing in moderate to heavy shade of a closed canopy forest. This area is not particularly arid with a short dry season during the coolest part of the year.

Taxonomic remarks

The flower-head of S. muhaensis sp. nov. (subgenus Capitulatus ) is completely clad in peduncle bracts when young, giving it a drumstick appearance ( Fig. 19A). During its further development, the long, lanceolate bracts of the partial inflorescences appear ( Fig. 19B–C), and afterwards the flower buds emerge from behind them. Up to this stage, the inflorescence is greenish coloured ( Fig. 19C). The stretching flower buds then show a greyish colouration on their tubes, lengthening to short longitudinal lines on the basal part of the lobes ( Fig. 18A). The greyish colouration of the flower outsides is maintained during anthesis ( Fig. 18B–C).

The superficially similar Sansevieria kirkii occurs regularly in coastal lowlands of the Indian Ocean in Tanzania and southern Kenya including the offshore islands. Although there are also numerous records from many other areas in tropical Africa that have been suggested to be S. kirkii , we are not aware of any true confirmation of its taxonomic identity. In any case, the altitude of the S. muhaensis type location is ca 800 m, markedly higher than coastal lowlands. Details of the morphological differences are given above in the diagnosis and in Table 3.

Tentative threat assessment

Critically endangered: CR E.

The limits of Kigoma City are either fully developed with houses, or soon will be. There is a lot of construction going on, and the whole area is platted for housing. Although Kigoma and nearby areas have now been intensively surveyed, this species was not found anywhere else. It is likely that some plants of S. muhaensis sp. nov. might persist for a while in neglected corners here and there, but the future of this species is most probably to be extinct in the wild in less than 3 generations (IUCN criterion E).

A rating of CR most accurately describes this situation according to our data.

Sansevieria sumbawangana M.Burkart, Constantine, Sikawa & Yinger sp. nov. urn:lsid:ipni.org:names:77370781-1 Figs 1, 20–24, Table 3

Diagnosis

This capitate Sansevieria is characterised by its peculiar leaf form ( Fig. 20), the extraordinary leaf width, the massive rhizome of up to 70 mm diameter, the almost uniform, very dark colouration of the flat leaves, and the protrusions on the fruits. The width relationship of the perianth lobes is also uncommon – in most species of Sansevieria , the outer lobes are a little bit narrower than the inner or of the same width, not wider as in S. sumbawangana sp. nov.

Etymology

Sansevieria sumbawangana sp. nov. is named for Sumbawanga Town, where this species was found for the first time.

Type material

Type

TANZANIA • Rukwa Region, Sumbawanga, Malangali Ward ; 1850 m a.s.l.; 5 Mar. 2020; B. Yinger & R.A. Sikawa YS 0317; holotype: NHT [000001154] .

Living specimens ex holotypo cultivated at TSF and POTSD.

Paratype

TANZANIA • Mbeya Region, Mbozi District ; 1612 m a.s.l.; 20 Oct 2021; B. Yinger & R.A. Sikawa YS 0930; NHT [000001158] .

Living specimens ex paratypo cultivated at TSF.

Description

Plant rhizomatous, stemless, vegetative height 416 mm, 2–5 leaves per shoot†† ( Fig. 20A). Rhizome subterranean but close to soil surface, runners short, to 100 mm long††, rhizome diameter 70 mm, inner rhizome cortex brownish orange 165B. Leaves ( Fig. 20) dispersed in all directions, upright to spreading, very stiff, to 1 m long and to 210 mm wide††, lanceolate, widest part above the middle, distal part rather shortly narrowed to a leathery 20–25 mm long tip, basal part without petiole, openly u-shaped to almost flat, central lamina ca 20 mm thick††, almost uniformly dark green, adaxial surface smooth, abaxial surface very smooth, both with many (ca 25) longitudinal, wavy fissures from base to tip ( Fig. 21), leaf edges somewhat wavy, narrowly red-brown and whitish. Inflorescence ( Figs 21–22) capitate, terminal from a fully leaved shoot; axis 385 mm long overall; peduncle 300 mm long, 20 mm in diameter, green with lighter tiny dots and lines, bearing 7 bracts to 78 mm long; some bracts dry, the fresh ones coloured greyish purple; flowering part 85 mm long, flowering head 236 mm in diameter excluding anthers and styles, very dense, 2–3 flowers per partial inflorescence; bracts of partial inflorescences 25–30 × 7–14 mm, herbaceous, lanceolate-elliptic, one- to five- but mostly three-nerved, no extrafloral nectar seen on them. Flowers large, longitudinally striate, on inarticulate, green pedicels 10 mm long, corolla outside coloured yellow green with brown dots on the tube, lobes coloured white inside, tube 90 mm long, lobes 32 mm long, overall flower length 122 mm, tube 3 mm wide at the narrowest point, 4 mm across the ovary, 5 mm across the distal part of closed flowers shortly before anthesis, inner lobes 3 mm, outer lobes 4 mm wide, all strongly curling back at anthesis, closed anthers 5 mm long, open anthers 4 mm long, filaments thread-like (not flattened), 36 mm long, style straight, 115 mm long excluding ovary, 38 mm exsert, i.e., 2 mm exceeding the filaments. Flowers opening at dusk, wilting in the morning, self sterile. Fruits (only seen unripe#, Fig. 23) rugose and with protrusions at their distal ends. Seeds unknown.

Ecology and distribution

There are presently two locations only where this species has been collected, including the type location. These are in the Rukwa and Mbeya regions, respectively, both in SW of Tanzania ( Fig. 1). The site of YS 0930 was on rocky slopes and in ravines under a largely closed canopy of trees and shrubs, which would completely shade the plants during the rainy season, but at the time of the visit at the height of the dry season let in plenty of light ( Fig. 24). YS 0317 was collected in a strongly conversed area on a termite mound beside a recently built house ( Yinger & Sikawa 2023c: fig. 19). Both sites are at rather high elevations, 1850 resp. 1612 m.

Taxonomic remarks

We are not aware of any species in the subgenus Capitulatus , to which this species clearly belongs, that appears to be closely related to S. sumbawangana sp. nov. A comparison with S. kirkii , S. bhitalae R.H.Webb & L.E.Newton and S. sinus-simiorum Chahin. , the only other species of the subgenus Capitulatus that are similar in overall size, is given in Table 3.

The bracts of partial inflorescences of capitate Sansevierias often have several nerves (e.g., S. kirkii , S. fischeri , S. bhitalae ), as is the case in S. sumbawangana sp. nov. Species from the other subgenera mostly have single-nerved bracts (but see, e.g., S. rosulata T.G.Forrest ; Forrest 2017).

Tentative threat assessment

Endangered: EN D.

The type location of this species is in an area that has been almost completely converted to agriculture and housing estates. There is almost no natural vegetation remaining in the area, although quite a few termite mounds remained. The plants there were persisting beside a termite mound close to several houses. Although we searched the surrounding area, we did not see any other plants of this species. There are three plants remaining at the type location.

We saw more plants in an area that is mostly undisturbed, on rocky slopes and in ravines within the drainage of Lake Rukwa (collected under YS 0930). Although it is risky to do a field identification without flowers, we believe that we have seen at least two more colonies in the vicinity of Lake Rukwa, comprising at least 200 plants. Although this area is not formally protected, it does not seem to be immediately threatened. The location and topography make it an unlikely site for farming or housing.

Regarding these circumstances, the appropriate category of threat for S. sumbawangana sp. nov. is EN (IUCN criterion D, <250 mature individuals) according to our data.

Parts of the side of the lake opposite where we found our collection are already within a reserve that might become part of an expanded national park. Its vegetation is quite different from the west side; there was only S. bhitalae s. lat. found.

In the TSF living collection there are several plants from other locations which, based on their foliage, might belong to this species, but they have not flowered yet. This option can lead to a reduction in the threat status of S. sumbawangana sp. nov.

Sansevieria rukwana M.Burkart, Piniely, Sikawa & Yinger sp. nov. urn:lsid:ipni.org:names:77370782-1 Figs 1, 25–27, Table 3

Diagnosis

Sansevieria rukwana sp. nov. seems to be similar to S. kirkii , but the leaves in S. rukwana are shorter and wider, lacking a pseudo-petiole as well as a strong ridge on the abaxial side but showing a silky gloss on both sides, characters different from that in S. kirkii . Also, the rhizome inner cortex is orange instead of brown as in S. kirkii , the peduncle, the bracts of the partial inflorescences and the styles all are shorter, and the flower odour is different in S. rukwana . The capitate but slightly elongate inflorescence (or its remnants, Fig. 25B) is typical for S. rukwana and indicates that it belongs to the subgenus Capitulatus .

Etymology

Sansevieria rukwana sp. nov. is named for Rukwa Region where this species is found.

Type material

TANZANIA • Rukwa Region; 1039 m a.s.l.; 19 Oct. 2021; B. Yinger & R.A. Sikawa YS 0925; holotype: NHT [000001157] .

Living specimens ex typo cultivated at TSF and POTSD.

Description

Acaulescent herb, rhizomatous, vegetative height to 1600 mm ††, to 620 mm #, 2–3 leaves per shoot. Rhizome belowground, ca 30 mm in diameter, forming short runners, colour of inner cortex dark reddish orange 172B. Leaves ( Figs 25A, 26) pointing to all directions, upright to spreading to almost horizontal, stiff but twistable, to 1600 mm long, to 110 mm wide, oblanceolate, slightly twisted, petiole missing, leaf base ca 21 mm wide, central lamina thickness 6 mm, basal thickness 16 mm, flat but u-shaped in cross-section, without a pronounced ridge on the abaxial side, surface very smooth on the adaxial side, smooth on the abaxial side, both sides with silk gloss†† and a heavy, conspicuous glaucous bloom; colour pattern distinct on the adaxial side, cloudy, without dark longitudinal lines, pattern less prominent on the abaxial side, forming transverse bands, lighter and darker parts 50: 50, with up to 9 dark longitudinal lines, colour pattern in older leaves weaker than in young ones; margin sinuate, red-brown and whitish; leaf tip leathery, to 29 mm long. Inflorescence ( Figs 26–27) terminal on fully leaved shoots, capitate, 223 mm long; peduncle 163 mm long, 20 mm thick, patterned with small dots and lines, dark greyish reddish brown 200A, with 4 bracts; peduncle bracts 46–114 mm long, dry at anthesis, light olive 152B; flower-bearing part of axis 60 mm long, flowering head 135 mm in diameter excluding anthers and styles, dense, 2–3 flowers per partial inflorescence, less in the uppermost part, 201 flowers counted on one head; bracts of partial inflorescences 17–23 mm long, 7–12 mm wide, herbaceous (not dry), lanceolate-elliptic, with up to 5 nerves, without extrafloral nectaries; pedicels inarticulate, 10 mm long, light olive 152A, wilted flowers not dropping. Flowers with flowery but astringent odour, greenish white 155C outside, wilted greyish yellow green 148C, with some pinkish striation most prominent on young buds ( Fig. 27A), 133 mm long overall; tube 100 mm long; lobes 33 mm long, inner lobes 4 mm wide, outer lobes 3 mm wide, strongly to intermediately curled back at anthesis; filaments greenish white 155C, 31 mm long, thread-like; anthers 4 mm long, strong yellow green 144C; style white, straight, 123 mm long above ovary, 45 mm exsert from tube mouth; stigma 1.5 mm wide, white; ovary ovoid with truncate apex, strong yellow green 144C; infructescence capitate but slightly elongate#. Fruits and seeds unknown.

Ecology and distribution

This species was collected only once in an area of steep wooded ravines and rocky slopes above streams within the Lake Rukwa drainage area. Although much of this area is still intact forest, the location of this collection was in a partially disturbed area where tree cover was mostly removed.

Taxonomic remarks

Sansevieria rukwana sp. nov. is superficially similar to S. kirkii . An overview of the differences is given in the diagnosis above and also in Table 3. Sansevieria kirkii is relatively widespread in Indian Ocean coastal lowlands, far away from the small and restricted W Tanzanian realm of S. rukwana . Although many records exist from a wide geographical scene that claim to be S. kirkii , they lack true confirmation of their taxonomic identity. Moreover, the proper taxonomy of S. kirkii var. kirkii and var. pulchra N.E.Br. is still unresolved ( Newton 2020; MB and U. Scharf, pers. obs.).

Tentative threat assessment

Endangered: EN D.

We found what we are certain is this species only once in a mostly undisturbed area. The colony that we saw is about 150 plants. This area is very difficult to navigate and there are vast areas of similar topography there. We saw a number of other plants of Sansevieria there, but nothing with the distinctive infructescence remnant of S. rukwana sp. nov. ( Fig. 25B). This area was under no obvious immediate threat because of its steep rocky topography, but recently, a mine for iron ore has been proposed very close to the type location; in two days of surveying this area, no other colonies were seen. Based strictly on what we have observed, its threat status is EN (criterion D, <250 mature individuals), although the situation might change drastically if mining begins.