'Endong', a rare variety of the farmed carrageenophyte Eucheuma denticulatum (Burman) Collins & Hervey from the Philippines

The variety described in this paper is rather a rare and interesting one. Locally called 'endong', this was discovered first in a farm in Tawi-Tawi, Sulu Archipelago, Philippines. During harvest, seaweed farmers used to mix this with 'tambalang' (Kappaphycus alvarezii (Doty) Doty ex Silva var. tambalang Doty, the 'cottonii' of commerce) because of the presumption of it producing the same carrageenan type as that of 'tambalang', viz., kappa-carrageenan. The two farmed varieties are similar in appearance. Complaints arose from seaweed processing plants when the resulting gelling properties (hard and brittle gel) expected of the kappa-carrageenan-producing 'tambalang' were not met. Because of its lax habit and long, smooth, and naked basal axes, 'endong' was initially thought to be related to 'tambalang' and differ from the farmed 'spinosum' (Eucheuma denticulatum (Burman) Collins & Hervey) whose typical or common form has shorter axes covered from base to apex with spinous determinate (ramuli) or indeterminate branchlets arranged irregularly and in whorls at predictable interval. However, a closer look at 'endong' shows that it also has spinous branchlets arranged in whorls, but confined to the apical portion of the branches. Moreover, its internal axial anatomy shows rhizoidal filaments forming a core. Both characters fit well the distinguishing taxonomic criteria established for E. denticulatum. Chemical characterization of its carrageenan and the determination of its phylogenetic affinities support our morphological findings. Hence, we report and describe 'endong' as a rare variety, and we name it E. denticulatum (Burman) Collins & Hervey var. endong Trono & Ganzon-Fortes var. nov. Tips to distinguish 'endong' from 'tambalang' are included in this paper to aid seaweed farmers in separating the two during harvest.