Rediscovery of Lagenandra erosa from Sri Lanka: update of description and conservation status Madola, Indrakheela Karunarathna, Peshala Pasan Yakandawala, Deepthi Yakandawala, Kapila Phytotaxa 2023 2023-10-27 622 3 227 235 6NSZM de Wit (1978: 36 - 38) de Wit 36 - 38 1978 [136,601,1556,1583] Liliopsida Araceae Lagenandra Plantae Alismatales 2 229 Tracheophyta species erosa   Type:—  CEYLON.  Bogner450( holotype M!;  isotypes C, M!). Stem creeping to erect, up to ca. 1 cmthick. Cataphylls ca. 4–10 cm. Petioles to ca. 18 cmlong, ca. 0.2–0.5 cmwide, sheath for ca. 4 cm, lower surface terete, upper surface flat and the margin slightly extending; Leaf blades upper surface dark green or green mixed with slight silver colour on surface /towards the margin, blade linear, ca. 8–26 × 0.5–4.0 cm, margins either crisped-toothed (erose) or not, acute to long-tapered at base and apex. Peduncle ca. 15 cmlong, 0.2–0.5 cmwide. Spathe light green to whitish/light yellow 10–16 ( 23 cmin cultivation) cm, slender, slightly to widely opened and somewhat twisted with no distinct warts, smooth outside or with protuberances; kettle ca. 1–3 × 1–2 cm, yellowish green to whitish (purple in cultivation?) outside, purple or whitish pink inside, with smooth longitudinal striations; limb to ca. 10 ( 20 cmin cultivation) x 0.6–1.2 cm, inside rugose-spongy, irregularly ribbed, marron or purple in colour and open slightly or widely; tail ca. 1–5 ( 10 cmin cultivation) x 0.1–0.2 cm. Spadix ca. 3.5 cm; pistillate flower zone ca. 1.3 × 0.4–1.0 cm; sterile zone ca. 1.4 cm; staminate flower zone ca. 0.3–0.5 × 0.3–0.4 cm; appendix ca. 0.3 × 0.1–0.2 cm, to pink. Pistils ca. 30–40; style broad and warty; stigma dome-shaped; ovule solitary. Stamens ca. 35–48. Infructescence up to 8.5 cmlong, prolate with 30–36 fruitlets, peduncle 4–6.5 cmlong, fleshy capsules with warty out-growths. Seeds 1–3, size ca. 0.4–0.6 × 0.2–0.3 cmand longitudinally ridged.   FIGURE 2.Habitat of  Lagenandra erosa; A. In the small rock pockets where the stream forms mini waterfalls. B. On the banks of the stream.   FIGURE 3.Habit of Lagenandra erosa.   FIGURE 4.  Lagenandra erosa; 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. Pistillate flower zone. G. Appendix and staminate flower zone. H. Infructescence and I. Seeds.   FIGURE 5.  Lagenandra erosa; A. Habit. B. Spathe. C. Infructescence and D. Seeds.  Note:— Nicolson (1987), during the revision of the Sri Lankan  Lagenandra, under the description of  L. erosastate as a note that ‘all veins on the lower leaf-surfaces are covered with branched protuberances’. During the present study we have noted that this is a character that is not consistent and could vary with growth conditions.  Habitat and ecology:—The population was rediscovered from a bank of a small stream.   Distribution, phenology and conservation status:—At the time of the first description of  L. erosain 1978, the locality of the plant was unknown as it was based on cultivated material imported from Sri Lankato Europe with no possible locality. During the present study,  L. erosawas rediscovered from a small stream in Molkawa, Kaluthara District, Sri Lanka, elevation 90 m, declaring a locality for a living population in the island. The population harboured around 60 mature and young individuals occurring along the stream bank/in small rock pockets. The population was spread over around 400 moccurring in small sub-populations. The stream is not within a protected area but inhabited by agricultural and home gardens and therefore subjected to anthropogenic activities. The cascading system is popular as a recreation site attracting local visitors. Further, flash floods caused by adverse climate changes also could affect the populations. Peak flowering of  L. erosawas observed from January–April. Fruiting from March to April. The calculated AOO accounted to 4 km 2while 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. erosabeing presently restricted to only one locality in the country, and the number of healthy individuals in the population is restricted to less than 60 mature individuals, scattered along the bank of a stream bordering human inhabited area subjected to anthropogenic activities, the population could be considered as under threat. Following the present IUCN guidelines (2022); based on geographic range, with only 4 km 2of EOO and AOO, this species qualifies for Critically Endangered category (CR) under the thresholds for both B1 and B2. Considering the fact that the plant population is restricted to a single stream and the associated anthropogenic activities number of locations is considered as 1 (a). Further, considering the interference of humans (illegal collections, sand mining and agricultural practices) and natural courses (bank erosion) and located outside a protected area, it is expected that the population of  L. erosais under severe threat with a projected decline in the population in future (b.ii). Considering these facts, the conservation status of  L. erosais re-evaluated and downgraded from Critically Endangered (Possibly Extinct) CR (PE) (The National Redlist 2020) to Critically Endangered category under Criterion B1ab (ii) + B2ab (ii).  Specimens examined:—  Ceylon, 1972,  Bogner450( holotype M! [M-0198896]).  Isotypes: Ceylon, 1972,  Bogner450( M! [M-0198897].  Paratypes: Ceylon, Cult. Botanischer Garten Munich, 1972,  Bogner450( WAG! [0058034, 0058035]);  Ceylon, no date,  Bogner450 US! [2946993]; Ceylon, no date,  Bogner450( K! [ K000499240, K000499241]);  Ceylon, Cult. Botanischer Garten Munich, 1973,  Bogner576( WAG! [1666000]).  Other specimens: Ceylon, no date, Bogner 450 ( US! [2946984]);  SRI LANKA, Western Province, Molkawa, Kaluthara District,  88 masl. Collected  09 January 2023,  Madola,  Karunarathna,  Yakandawala&  Yakandawala L272( C!, K!, PDA!). 4440306306 [219,581,1632,1654] M, C Sri Lanka Bogner 2 229 2 holotype 4440306301 [586,738,1632,1654] M, C Sri Lanka Bogner 2 229 2 holotype 4440306309 [483,1160,806,833] M Sri Lanka Bogner 7 234 2 holotype 4440306304 M Sri Lanka Bogner 7 234 2 holotype 4440306310 M Bogner Sri Lanka Bogner 7 234 2 holotype 4440306305 [390,901,878,905] K Bogner Sri Lanka Ceylon 7 234 K000499240, K000499241 1 paratype 4440306303 K Bogner Sri Lanka Ceylon 7 234 K000499240, K000499241 1 paratype 4440306307 [317,1246,914,940] WAG Bogner Sri Lanka Cult. Botanischer Garten Munich 7 234 1 4440306302 WAG Bogner Sri Lanka Cult. Botanischer Garten Munich 7 234 1 4440306308 2023-01-09 C, K, PDA Madola & Karunarathna & Yakandawala Sri Lanka 88 Kaluthara District Molkawa 7 234 L272 1 Western