Lagenandra limbusleviterapertae Madola, D.Yakandawala & K.Yakandawala, 2023

Madola, Indrakheela, Yakandawala, Deepthi & Yakandawala, Kapila, 2023, Lagenandra limbusleviterapertae, a new addition to the genus Lagenandra (Araceae) from Sri Lanka, Phytotaxa 601 (1), pp. 61-70 : 63-69

Lagenandra limbusleviterapertae Madola, D.Yakandawala & K.Yakandawala , sp. nov. ( Figs. 2–6 )

Lagenandra limbusleviterapertae can be differentiated from all other described species on the basis of the linear limb (5.0–9.5 × 1.0– 1.5cm), where the limb opens only at the base of the tail extending only about 1/5 of the length and the width of the opening remains <5 mm.

Type:— SRI LANKA, Southern Province, Galle District, Hiyare Forest Reserve of Sri Lanka , 110 m asl. Collected 11 October 2018, Madola, Yakandawala & Yakandawala L48 (holotype PDA!, isotypes PDA!, K!) .

Evergreen large herb with creeping to erect rhizome ca. 1–3 cm in diam. Cataphylls ca. 7–15 cm, 1–2 keeled. Petiole ca. 16–33 cm long, ca. 0.3–0.9 cm wide, sheath ca. 3–9 cm long, unequal. Leaf blades upper surface green/ dark green, lower surface green/dark green, rarely dark purple in some plants, blades more or less oblong or linear, apex narrowly acute, base gradually tapering/acute or slightly rounded, margin entire, blade ca. 17–28 × 4–9 cm; midrib visible on both surfaces and prominent on the lower surface. Peduncle ca. 4–13 cm long, 0.3–0.5 cm width. Spathe light/dark maroon or light cream, with no distinct warts, ca. 9–16 cm long, kettle ca. 1.2–1.7 × 1.1–1.3 cm, dark maroon smooth longitudinal striations inside; limb ca. 5.0–9.5 × 0.9– 1.5 cm, un-twisted, opens only at the base of the tail extending only about 1/5 of the length and width of the opening remains <5 mm, cream and/or light maroon with regular white stripes and/or vertically irregularly pattern; tail ca. 1.2–6.0 × 0.1–0.3cm. Spadix ca. 1.2–2.0 cm long; pistillate flower zone ca. 0.4–0.6 × 0.5–0.8cm; sterile zone ca. 0.2–0.7 cm long; staminate flower zone ca. 0.3–0.5 × 0.3–0.4 cm; appendix ca. 0.1–0.3 × 0.1–0.2 cm. Pistils ca. 35–45, closely arranged. Style clearly visible. Staminate flowers ca. 60–70. Infructescence up to 19 cm long (including the peduncle), prolate, capsules fleshy up to 30–35, with warty out-growths. Seeds 1–2, size ca. 0.5–0.7 × 0.2–0.4 cm and longitudinally ridged.

Distribution, phenology and conservation status:— To date distribution of L. limbusleviterapertae appears to be restricted to one locality in Sri Lanka, which is close to the Reservoir in the Hiyare Forest Reserve. The population is spread along about 50 m on the side of a streamlet and consists of about 130 young and mature individuals.

Hiyare Forest Reserve is a Tropical wet lowland evergreen forest located in the Galle district (low country wet zone) extended over an area of 250 ha which consists of 22.22 ha of man-made reservoir ( De Silva, 1996). The Tributary of the river Gin Ganga, the stream Mahadola rises in the western part of the catchment and field studies conducted revealed high biodiversity among flora and fauna including many endemics ( Silva, 1996, Hapuarachchi & Kathriarachchi, 2012).

Peak flowering of L. limbusleviterapertae was observed from November-April and fruiting from January-July and November. Occasionally flowering in May to June.

The calculated AOO accounted to 4 km 2 while we were unable to calculate the EOO due to the presence of only one data point. Therefore, the EOO was also taken as equal to AOO. Considering the facts that L. limbusleviterapertae being restricted to only one locality in the country, and the number of healthy individuals in the population is restricted to around 130 young and mature individuals, scattered along the bank of a streamlet in the reservoir. Following the present IUCN guidelines (2022); based on Criterion B and C this species qualifies for Critically Endangered category (CR) under the thresholds for B1, B2 and C2. Further evaluation under the Criterion B, B1 and B2, based on geographic range, with only 4 km 2 of EOO and AOO, number of locations is considered as 1 (a) and the subpopulations exhibited a continuing decline in the quality of habitat (iii) and number of mature individuals (v). When considering all these facts, L. limbusleviterapertae qualifies for CR category under Criterion B1ab (iii, v) + B2ab (iii, v). According to the Criterion C; Small population size and decline, where the number of mature individuals been <250, and with an observed, estimated, projected, or inferred continuing decline in the number of mature individuals in each subpopulation C2a (i), qualifies for the CR category under Criterion C2. Considering all these facts, L. limbusleviterapertae qualifies for Critically Endangered category under Criterion B1ab(iii, v)+B2ab(iii, v)+C2a(i)

Habitat:— The plants inhabit the banks of a shady streamlet in the Tropical Low Country Evergreen Rain Forest.

Vernacular Name:— ‘Hiyare kethala’ (Sinhala).

Eponymy:— The species name is formed by a conjunction of the Latin wording for limb, limbus; slightly, leviter and open, aperta (apertae). Adopted here to the highlight the distinctive feature of the spathe, the slightly opened limb.

Additional specimens examined (paratypes):— Hiyare Forest Reserve , 111 m asl. Collected 16 January 2021, Madola, Yakandawala & Yakandawala L188 ( PDA!); Hiyare Reservoir, 20 Nov. 1971, Balakrishnan 993 ( US!) .

A taxonomic key modified from Nicolson (1987) Madola et al. (2021a) Madola et al. (2021b) and Madola et al. (2022) including the new species, L. limbusleviterapertae is given below.

1. The whole spathe, standing well above the leaves. Leaves aligned more or less parallel to the substrate .......................................... ........................................................................................................................................... L. peradeniyae Madola et al. (2022: 115) .

– Spathe placed below the leaves, in some cases only the tail and limb are placed above the leaves ( L. bogneri and L. erosa ). Leaves not placed horizontally on the soil......................................................................................................................................................2

2. Spathe distinctly warty outside...........................................................................................................................................................3

– Spathe smooth or merely roughened outside by papillae...................................................................................................................6

3. Warts large (1.5–3.0 mm long); spathe limb abruptly globular-inflated above the kettle.................................................................... .......................................................................................................................... L. ovata (Linnaeus 1753: 967) Thwaites (1864: 334)

– Warts small (to 1.0 mm); spathe limb subcylindric............................................................................................................................4

4. Spathe large (more than 10 cm long); pistillate flowers more than 60........................................ L. praetermissa de Wit (1983: 299)

– Spathe small (up to 10 cm); pistillate flowers less than 40 ................................................................................................................5

5. Spathe outside with few distinct irregular warts. Leaves linear lanceolate to linear ovate.................................................................. .............................................................................................................................................. L. wayambae Madola et al. (2021: 217)

– Spathe outside, rugose, not with distinct warts. Leaves broadly elliptic or broadly lance-ovate......................................................... ......................................................................................................................... L. lancifolia ( Schott 1857: 221) Thwaites (1864: 334)

6. Leaf-blade sublinear, ca. 10 × longer than broad...............................................................................................................................7

– Leaf-blade ovate-lanceolate, to 5 × longer than broad.......................................................................................................................8

7. Leaf-blade to 50 cm long, margins smooth. Inside of spathe limb strongly laterally ribbed, outside dark purple ............. L. koenigii

– Leaf-blade to 20 cm long, margins erose. Inside of spathe limb rugose spongy, outside green ............................................. L. erosa

8. Spathe limb, inflated and opening subhorizontally .......................................................................... L. jacobsenii de Wit (1983: 291)

– Spathe limb not inflated sub-erect, cylindrical, and opening subvertically\ ......................................................................................9

9. Spathe yellow-green, limb inside surface yellowish white .............................................................. L. bogneri de Wit (1978: 33–34)

– Spathe maroon, limb inside surface maroon ....................................................................................................................................10

10. Limb un-twisted................................................................................................................................................................................11

– Limb twisted.....................................................................................................................................................................................12

11. Spathe light maroon/violet; limb opens up widely and is placed 45° to the kettle ........... L. kalugalensis Madola et al. (2021: 190)

– Spathe light/dark maroon or light cream; limb opens up slightly (<5mm) at the base of the tail.................. L. limbusleviterapertae

12. Leaf blade small (upto 20 × 4 cm); narrowly ovate to lanceolate; dark green, silver margin conspicuous, abaxial surface smooth .. .......................................................................................................................................................... L. thwaitesii Engler (1879: 621)

– Leaf blade large (upto 28 × 5–10.5 cm); ovate to narrowly ovate; light green; with a faint silver margin, abaxial surface rugrose .. ............................................................................................................................................ L. srilankensis Madola et al. (2021: 193)

Figures

FIGURE 2. Habitat of Lagenandra limbusleviterapertae, on the banks of the streamlet.

FIGURE 3. Habit of Lagenandra limbusleviterapertae; A. Leaves with lighter green upper surface and light cream mixed with marron spathes. B. Leaves with dark green upper surface and purple lower surface and dark marron spathe. C. Leaves with dark green upper surface maroon spathe., all occurring together along the stretch of the streamlet.

FIGURE 4. Variation in leaf and spathe colour of Lagenandra limbusleviterapertae; A1. and A2. Leaves with lighter green upper surface and light cream mixed with marron spathes. B1. and B2. Leaves with dark green upper surface and maroon spathe.C1. and C2. Leaves with dark green upper surface and purple lower surface and dark marron spathe. Note that A1. And B1. are upper leaf surfaces while C1. is lower surface.

FIGURE 5. Lagenandra limbusleviterapertae;A. Leaf. B. and C. Spathe from different angles showing the opening in the limb. D. Spathe dissected and opened. E. Kettle with the spadix. F. Appendix and staminate flower zone. G. Pistillate flower zone. H. Infructescence and I. Seeds.

FIGURE 6. Lagenandra limbusleviterapertae; A. Habit. B. Spathe. C. Infructescence and D. Seeds.