Alatina alata (Reynaud, 1830)

Figs. 2A–D, 3A–I

Collected samples: XC_38, Xcalak, Quintana Roo, Mexico, 18°16’14.7”N, 87°50’04.5”W; 1 m; December 2006; 2 adult specimens, BH=5.4/ 5.4 cm, IPD=4.0/ 3.4 cm . MCS_1, Mexican Caribbean Sea, Mexico; 1 juvenile specimen, BH= 1.2 cm, IPD= 0.9 cm . SQR_96_1, Southern Quintana Roo, Mexico; January 2007; 1 adult specimen, BH= 8.2 cm, IPD= 5.6 cm . BEL_65_1, Front of Hopkins, Belize; 16°41’34.1”N, 87°29’25.1”W; 25–50 m; January 2007; 1 juvenile specimen, BH= 1.3 cm, IPD= 1.1 cm .

Zooplankton collection: ECO-CH-Z _00203, northwest Cozumel, Quintana Roo, Mexico; 20°41’00”N, 86°16’00”W; 0–5 m; November 1991; 28°C; 36 PSU; 1 juvenil specimen, BH= 0.6 cm, IPD= 0.7 cm; as Carybdea alata . ECO-CH-Z _00211, northwest Chinchorro Bank, Quintana Roo, Mexico; 18°29’05”N, 87°36’00”W; 0–5 m; February 1991; 35 PSU; 1 juvenil specimen, BH= 0.5 cm, IPD= 0.4 cm; as Carybdea marsupialis . ECO-CHZ_00226, northwest Cozumel, Quintana Roo, Mexico; 20°41’00”N, 86°16’00”W; 0–5 m; November 1991; 28°C; 36 PSU; 1 adult specimen, BH= 3.1 cm, IPD= 2.5 cm; as Carybdea alata . ECO-CH-Z _00227, Sian Ka’an Biosphere Reserve, Quintana Roo, Mexico; 19°34’03”N, 87°20’04”W; 0–5 m; May 1991; 27.5°C; 36 PSU; 1 juvenil adult BH= 1.4 cm, IPD= 0.9 cm; as Carybdea marsupialis .

Citizen science (Blackwater Cozumel): Cozumel, Quintana Roo, Mexico; 2023; Obs. Frida Yolotzin Jonguitud. Cozumel, Quintana Roo, Mexico; November & December 2021, May & December 2023, June 2024; Obs. Robert Stansfield. Cozumel, Quintana Roo, Mexico, 20°27’59.5”N, 86°59’24.2”W; 0–3 m; August 2024; 31°C; Obs. Frida Yolotzin Jonguitud .

Nematocysts: bands along the length of the tentacles, undischarged, oval, heterotrichus microbasic p-euriteles 21–23 μm ± 1.8 x 13–14 μm ± 0.4 and undischarged holotrichus isorhizas 14–15 μm ± 0.5 x 13–14 μm ± 0.4.