Eucheilota duodecimalis (A. Agassiz, 1862) Phialium dodecasema (Haecke, 1879). Phialium duodecimalis (A. Agassiz, 1862). Materials Type status: Other material. Occurrence: individualCount: 2; occurrenceID: F2E14B0B-E093-5DAE-8314-DF7D10B71423; Taxon: kingdom: Animalia; phylum: Cnidaria; class: Hydrozoa; order: Leptothecata; family: Lovenellidae; genus: Eucheilota; Location: country: Colombia; stateProvince: Córdoba; municipality: San Antero; locality: E 3; verbatimDepth: 0.5-3 m; verbatimCoordinates: 9°24'11.47"N, 75°47'43.63"W; Event: eventDate: 02-04-2024; Record Level: collectionCode: LZUC-CD. C-0105 Type status: Other material. Occurrence: individualCount: 93; occurrenceID: A6F45DF1-82B6-5ECF-A360-8308142F2CAE; Location: country: Colombia; stateProvince: Córdoba; municipality: San Antero; locality: E 4; verbatimDepth: 0.5-3 m; verbatimCoordinates: 9°24'55.02"N, 75°46'25.32"W; Event: eventDate: 02-26-2024 / 05 -19-2024 Type status: Other material. Occurrence: individualCount: 178; occurrenceID: A17D4637-EC8E-518F-9456-2172D947F833; Location: country: Colombia; stateProvince: Córdoba; municipality: San antero; locality: E 5; verbatimDepth: 05-3 m; verbatimCoordinates: 9°26'33.73"N, 75°46'1.20"W; Event: eventDate: 02-26-2024 / 05-19-2024 Type status: Other material. Occurrence: individualCount: 120; occurrenceID: E9B9905F-DAAF-523B-BA67-4B22BE70207F; Location: country: Colombia; stateProvince: Córdoba; municipality: San Antero; locality: E 6; verbatimDepth: 0.5-3 m; verbatimCoordinates: 9°26'52.79"N, 75°43'51.47"W; Event: eventDate: 02-26-2024 / 05-19-2024 Type status: Other material. Occurrence: individualCount: 121; occurrenceID: 0CCF5262-5FD5-5EBE-AD64-C86AE6F6983E; Location: country: Colombia; stateProvince: Córdoba; municipality: San antero; locality: E 7; verbatimDepth: 0.5-3 m; verbatimCoordinates: 9°27'28.14"N, 75°48'4.10"W; Event: eventDate: 02-26-2024 / 05-19-2024 Description Umbrella hemispherical, 0.3-1.1 mm in height and 0.1-1.5 mm in width; mesoglea uniform; manubrium short and narrow; four simple radial canals; four interradial “ gonads ” located in the distal region of the radial canals, near the tentacular swellings. Mature small medusae were recorded with developed germ sacs; broad velum; four large, conical tentacular bulbs, each with a hollow tentacle and one to three pairs of lateral cirri; 12 closed statocysts, three per quadrant, two flanking the tentacular bulbs and one positioned inter-radially (Fig. 2). Diagnosis Four tentacles, with conical tentacular bulbs with a pair of lateral cirri; 12 statocysts, three per quadrant; marginal warts absent (Agassiz 1862, Bouillon 1999, Wang et al. 2018). Distribution Western Atlantic, from the United States to southern Mexico and South America, from Brazil to Uruguay (Tronolone 2001, Migotto et al. 2002, Tronolone 2007, Nagata et al. 2014, Oliveira et al. 2016 and Ríos 2018). Pacific Ocean, in Ecuador and Mexico (Segura-Puertas et al. 2003, Mujica and Andrade 2019) (See Fig. 3). Taxon discussion The observed specimens have a mean size of 0.6 mm in height and 1.0 mm in diameter, which are smaller than sizes reported by other authors (2.5 mm in diameter), such as Kramp (1961) and Bouillon (1999), but similar to that documented by Nagata et al. (2014) (1.3 mm in diameter). In general, E. duodecimalis shows very low morphological variability. The analysed specimens were consistent with the original descriptions provided by Agassiz (1862), Bouillon (1999) and Wang et al. 2018.

Published as part of Llorente-Vega, Jorge L, Cedeño-Posso, Cristina & Quirós-Rodríguez, Jorge A., 2025, First record of two Leptothecata medusae (Cnidaria, Hydrozoa) in Colombia with annotations on their distribution and ecology, pp. e 138523 in Biodiversity Data Journal 13 on page e138523, DOI: 10.3897/BDJ.13.e138523