Proposed conservation

Silva, Nilanka, Dasanayaka, Shamila, Yakandawala, Deepthi & Yakandawala, Kapila, 2025, Taxonomic resolution of the Elaeocarpus hedyosmus Zmarzty (Elaeocarpaceae) species complex in Sri Lanka using an integrative approach, Phytotaxa 706 (2), pp. 101-128 : 117-119

Proposed conservation status

Elaeocarpus hedyosmus is typically found on degraded land near watercourses or streams. Although these areas are no longer directly connected to the watercourses, the sloping and degraded nature of the habitat hints at the historical presence of more direct water access.

Elaeocarpus hedyosmus subsp. hedyosmus , the type of E. hedyosmus exhibits a very restricted distribution with very few mature individuals (less than 10 mature individuals and no young plants/seedlings observed) scattered as isolated populations or individuals. We were unable to observe any members from the type locality. Most of this land is occupied with tea plantations and human occupation. The EOO equals to 412.208 km 2 while the AOO value was 89.37 km 2. Following the present IUCN (2024) guidelines, based on Criteria B; the geographic range, considering EOO and AOO, as both values are between 100 km 2 –5000 km 2 and 10 km 2 –500 km 2 respectively, the species qualifies for the Endangered category (EN) under the thresholds for B1 and B2. In addition, to qualify for EN, at least two of the three specified conditions should be met: since the populations are severely fragmented and with limited number of locations, degraded habitat health and with less than 10 mature individuals, the species fulfils the conditions (a) [Severally fragmented]; (b) [Continuing decline observed, estimated, inferred or projected in any of; (iii) area, extent and /or quality of habitat; (v) number of mature individuals]. Further based on Criteria D, as the number of mature individuals are less than 50 the subspecies qualifies for CR category. Although E. hedyosmus subsp. hedyosmus falls within the EN category based on its geographic range, its range is close to the threshold of the CR category. Further, all the populations are represented by few mature individuals (less than 10) with no regeneration observed in the wild, the decision was taken based on Criteria D. The conservation status of Elaeocarpus hedyosmus subsp. hedyosmus is decided as CR D.

Elaeocarpus hedyosmus subsp. grandidomatiatus (EOO = 540.06 km 2 and AOO = 93.67 km 2) based on Criteria B, as both EOO and AOO values are between 100 km 2 –5000 km 2 and 10 km 2 –500 km 2 respectively, the taxa qualify for Endangered category under the thresholds for both B1 and B2. Considering the other conditions to fulfil, the habitat health of most of the populations were recorded as degraded. Many occur along streams banks where the present flash floods with extreme weather conditions have affected their stability, fulfilling condition (b) (iii). Further based on Criteria D, as the number of mature individuals are less than 50 the subspecies qualifies for CR category with a less than 20 mature individuals encountered in the wild. Although E. hedyosmus subsp. grandidomatiatus falls within the EN category based on its geographic range, its range is close to the threshold of the CR category. However, as all the populations are represented by few mature individuals occur in degraded habitats with no regeneration observed in the wild, the decision was taken based on Criteria D. The conservation status of Elaeocarpus hedyosmus subsp. grandidomatiatus is decided as CR D.

Elaeocarpus hedyosmus subsp. subobscurus (EOO = 2347.76 km 2 and AOO = 250.82 km 2) based on Criteria B; the geographic range, considering EOO and AOO, as both EOO and AOO values are between 100 km 2 –5000 km 2 and 10 km 2 –500 km 2 respectively, the taxa qualify for Endangered category under the thresholds for both B1 and B2. Considering the other conditions to fulfil, the habitat health of most of the populations were recorded as degraded. Many occur along streams banks where the present flash floods with extreme weather conditions have affected their stability, fulfilling condition (b) (iii). The conservation status of Elaeocarpus hedyosmus subsp. subobscurus is decided as EN B1+B2, b (iii).

The present study underscores the critical need to conserve the genetic diversity of even within a species across various climatic zones and ecological gradients, where unique genetic variations emerge. Populations distributed across diverse environments can develop locally adapted traits, resulting in distinct population-level genetic compositions that enhance the species’ overall genetic diversity and evolutionary potential. Recognizing and preserving these adaptations strengthens conservation efforts by supporting a more resilient gene pool, making this approach a powerful biodiversity conservation strategy. However, without taxonomic distinctness for below-species-level taxa, these efforts may struggle to gain necessary support from policymakers and development initiatives. Thus, this study highlights the essential role of taxonomy in conserving biodiversity and genetic diversity, below species.

Key to the Elaeocarpus hedyosmus subspecies occurring in Sri Lanka (a complete key for the Elaeocarpus species is given in Silva et al. (2021)

1. Leaf apex slightly acute to obtuse, domatia prominent, stone surface deeply concave-sculptured with many irregular blunt projections ..........................................................................................................................................................................................2

- Leaf apex acute, domatia inconspicuous, stone surface deeply concave-sculptured with many irregular, sharp projections ............. ........................................................................................................................................................ E. hedyosmus subsp. subobscurus 2. Leaves slightly obovate, apex slightly acute, domatia less prominent............................................. E. hedyosmus subsp. hedyosmus

- Leaves elliptic, apexes obtuse, domatia very prominent....................................................... E. hedyosmus subsp. grandidomatiatus