Udotea cyathiformis Decaisne 1842: 106

Acosta-Calderón, Julio Adulfo, Hernández-Rodríguez, César, Mendoza-González, Ángela Catalina & Mateo-Cid, Luz Elena, 2018, Diversity and distribution of Udotea genus J. V. Lamouroux (Chlorophyta, Udoteaceae) in the Yucatan peninsula littoral, Mexico, Phytotaxa 345 (3), pp. 179-218 : 194

Udotea cyathiformis Decaisne 1842: 106

Type Locality:— FRANCE, Iles des Saintes, Guadeloupe, Lesser Antilles.

Morphology: — Thalli to 4.5 cm tall, anchored on substrata by a small fibrous rizoidal mass. Stipe cylindrical, tinny 13 mm length, 2 mm diameter. Evident transition between stipe and blade. Blade spatulate, light green, delicate, longer (2.9 cm) than wider (1.5 cm), acute lower margin, multistratose, ecorticate, lightly zonate and calcified (Fig. 22).

Anatomy: — Blade siphons without lateral appendages, dichotomously branched, 45–55 μm in diameter (Fig. 23), distance between each dichotomy varies from 500 to 900 μm, supradichotomic constriction 20–30 μm length, 20 μm in diameter. Stipe siphons adjacent to lateral appendages 70–100 μm in diameter, appendages peduncle 200–250 μm length, 40 μm in diameter, appendages irregularly branched, terminating in asymmetrical dichotomies, with swollen or flattened apices (Figs. 24, 25).

Reproduction: — Vegetative

Material examined: — MEXICO. Yucatan, Santa Clara, 26 June2011, L. E. Mateo Cid, A. C. Mendoza González, ENCB 23099. MEXICO. Quintana Roo, Arrecife Colombia, Isla Cozumel, 14 September 1993, R. B. Searles, R. Robles, ENCB 12759. MEXICO. Quintana Roo, Arrecife Santa Rosa, Isla Cozumel, 02 June1996. R. Robles, E. Caister, M. Volovsek, ENCB 12745.

Geographic distribution: — Bermuda, Florida, North Carolina, Texas, Belize, Panama, Bahamas, Barbados, Cuba, Haiti, Guadeloupe, Jamaica, Lesser Antilles, Puerto Rico, Virgin Islands, Brazil, Venezuela, South China Sea, Mexico.

Habitat: — Rocky platforms subtidal to 2 m depth.

Comments: — Decaisne (1842) described for the first time this species, assigned the epithet of cyathiformis for its cup shaped frond (cyathis) and a cylindrical stipe. The description was made with specimens from the Antilles, but the author did not show any illustrations. Howe (1909) presented a more detailed description of the morphology of the blade, blade siphons, and the lateral appendages of the stipe siphons, also add information about the diameter of the blade siphons. In the work of Littler & Littler (1990) more precise description and illustrations are presented about the shape of the apices of the blade siphons and the lateral appendages of the stipe siphons. Udotea cyathiformis has been characterized by a cup shaped blade ( Decaisne 1842, Howe 1909, Littler & Littler 1990, Collado-Vides et al. 2009), however in this study the revised specimen shows a spatulate blade with an acute lower margin. The shape of stipe appendages agrees with those described by Littler & Littler (1990), and the dimensions of blade and stipe siphons are also consistent with description of Littler & Littler (1990) and Collado-Vides et al. (2009). The presence of this taxon could not be confirmed by the collection in Quintana Roo littoral, as mentioned by Huerta-Múzquiz et al. (1987), Mendoza-González & Mateo-Cid (1992), Dreckmann et al. (1996), Aguilar-Rosas et al. (1998), Mendoza-González et al. (2000), Aguilar-Rosas et al. (2001) and Collado-Vides et al. (2009), neither in the Campeche shoreline ( Mateo-Cid et al. 2013), possibly because this species is distributed at depths greater than those sampled in this study and only one specimen was obtained from the Yucatan coast. Udotea cyathiformis is recorded for the first time for the Yucatan littoral.