Rhizophora stylosa (Rhizophoraceae), previously known from India (Andaman and Nicobar Islands), China to Indo-China, and the Pacific Island, is reported here as a new record from coastal areas with muddy-sandy, sandy or sandy-rocky substrates at Ko Lidi and Ko Bulon Le, within Mu Ko Phetra National Park, La-ngu District, and at Ao Talo Wao, Ko Tarutao, Tarutao National Park, Mueang Satun District, Satun Province, Peninsular Thailand. A detailed morphological description, illustrations and a distribution map of the species are provided, along with notes on distribution, habitat and ecology, phenology, a preliminary conservation assessment, etymology and specimens examined. In addition, Rhizophora stylosa is lectotypified, the Thai vernacular name “Kongkang phetra” is herein proposed for this species, and an updated identification key to the species of Rhizophora in Thailand is presented. The species is currently assessed as Least Concern [LC] under the IUCN conservation status. Furthermore, detailed descriptions of leaf anatomical features and pollen morphology are provided. The thick cuticles, sunken stomata, large hypodermal cells, and cork warts are adaptive anatomical features of leaves in Rhizophora that live in the mangrove environments. The pollen grains of Rhizophora stylosa are tricolporate, prolate spheroidal or oblate spheroidal shapes, small-sized, and reticulate exine sculpturing.

Four species of Korthalsia are found in Thailand: K. flagellaris, K. laciniosa, K. rigida, and K. scortechinii. We present the comparative vegetative morphology, a key to the species, distribution, ecology, preliminary conservation assessments, utilization, and specimens examined. Korthalsia flagellaris is lectotypified here in a second-step. Three Thai Korthalsia species are confined to the peninsular region: K. flagellaris, K. scortechinii and K. rigida. The first, K. flagellaris, is known only from Narathiwat province and is restricted to peat swamp forests. The second, K. scortechinii, is myrmecophilous and found only in Narathiwat in lowland tropical evergreen rainforests. The third, K. rigida has a wider distribution and is known from Ranong, Trang and Narathiwat provinces in lowland tropical evergreen rainforests. Lastly, Korthalsia laciniosa is the most widespread species of the genus in both the south-eastern and peninsular regions of Thailand in lowland tropical evergreen rainforests. All Thai Korthalsia species are currently assessed as Least Concern (LC) under the IUCN conservation status. In Thailand, Korthalsia is used for traditional tools, furniture components, and fishery equipment. Its stems are valued in local crafts, while the young shoots are occasionally consumed as food.

Rattans of the genus Korthalsia are ecologically and economically important non-timber forest resources in Southeast Asia, yet their conservation is limited by knowledge of species-specific distribution patterns and environmental constraints. We modeled the potential distributions of four Korthalsia species (K. flagellaris, K. laciniosa, K. rigida, and K. scortechinii) using species distribution models (SDMs). Models were fitted in R using the sdm package, and ensemble maps were generated by combining predictions from Random Forest (RF), Generalized Linear Models (GLMs), Generalized Additive Models (GAM), and GLMnet. The top predictors influencing habitat distribution included soil physical structure, atmospheric moisture demand, and canopy light availability. The dominance of these factors reflects three distinct and non-interchangeable environmental axes that regulate belowground moisture dynamics, atmospheric constraints on gas exchange, and the energetic requirements for recruitment. All four species ensemble models significantly outperformed the null model, and spatial block cross-validation (k = 5, 200 km blocks) indicated a marginal drop in area under the curve (AUC) values, confirming a predictive signal under geographically independent evaluation. Ensemble suitability maps identified Peninsular Malaysia, Borneo, and Sumatra as centers of predicted habitat. Core habitat was estimated to be less than 0.6% of total suitable area for all species, ranging from 980 km² (K. scortechinii) to 19,256 km² (K. rigida), with anthropogenic modification exceeding 50% in the core habitat in K. flagellaris and K. rigida. These results provide the first species-specific baseline for these Korthalsia across Southeast Asia, supporting more targeted conservation and restoration planning under varying habitat constraints.