*2.2. Morphological Analyses and Specimen Collection*

Morphological data for zoantharian colonies (*n* = 30) were recorded at three field sites, SB, PB, and GA in June 2019 from the northeastern coast of Toco, Trinidad. A hand-held caliper was used to measure oral disk diameter of 3 opened polyps per colony. Physical characteristics of each polyp, such as tentacle count and color, oral disc color, and polyp form (immersae, intermediate, liberae, see 4, 21 were recorded, together with in situ photographs, which were used to assist in identification (see Table 1). Additional samples were also collected at three other sites between December 2019–February 2020, and were primarily collected for genetic analyses. Samples were collected in areas with high wave action (open habitat exposed to waves), and low wave action (rocky habitat protected from waves). A total of 13 specimens (3–5 polyps per specimen) were collected from SB, PB, and GA. Additionally, specimens were collected at inaccessible areas along the northeastern coast, such as Galera Point (GP) (*n* = 1 specimen) located just left of the Keshorn Walcott Toco Lighthouse, which is 1 km east of PB, and has a mixture of rocks and tide pools where zoantharians were observed to have extensive coverage. Additionally, samples were collected from Straight Bay (StB) (*n* = 2 specimens), 1 km west of SB, and from western SB (WSB) (*n* = 5 specimens), which is an accessible area, but less frequented by local visitors.




**Table 1.** *Cont.*

Abbreviations: PB = Pequelle Bay, SB = Salybia Bay, TLH = Toco Lighthouse, GA = Grande L'Anse, StB = Straight Bay, WSB = Western Salybia Bay. All samples (# represents number) were collected during extreme low tide (~0.31 m depth).

> Altogether specimens were collected at six sites by snorkeling along the northeast coast of Toco, Trinidad between June 2019 to February 2020. A total of 3–5 closed individual polyps were excised from colonies (specimen) using scalpel and tweezers, and placed in 1.5 mL collection vials with 95% ethanol (Carolina Biological. Burlington, NC, USA), then stored at −20 ◦C. Specimens are housed at the Andrews Science Building, University of Tennessee-Southern (formerly Martin Methodist College), Pulaski, Tennessee, United States. Specimen catalog nos. are TRIN-2019-001 and TRIN-2020-001.
