Udotea fibrosa D.S. Littler & M.M. Littler 1990: 226

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 : 199-201

Udotea fibrosa D.S. Littler & M.M. Littler 1990: 226

Type locality:— BELIZE. Carrie Bow Cay.

Morphology:—Thalli to 6.5 cm tall, anchored on substrata by a bulbous mass of entangled rhizoidal siphons. Stipe cylindrical 6–12 mm long, 2–4 mm in diameter. Evident transition between the stipe and blade. Blade spatulate, green, longer (4–5 cm) than wider (1–1.5 cm), lower margin oval, multistratose, ecorticate (no lateral appendages), calcified, and not zonate (Figs. 45, 46).

Anatomy: — Blade siphons without lateral appendages, dichotomously branched, 50–70 μm in diameter, supradichotomic constrictions 15–17 μm length, 18–23 μm in diameter (Fig. 47), some blade siphons torulose (Fig. 48). Stipe siphons adjacent to lateral appendages 27–47 μm in diameter, appendages peduncle 90–150 μm length, 20–30 μm in diameter. Appendages dichotomously branched 2–3 times, with swollen dichotomously tips (Fig. 49).

Reproduction: — Vegetative

Material examined: — MEXICO. Quintana Roo, Isla Mujeres, 16 June 2014, J. A.Acosta Calderón, L. E. Mateo Cid, A. C. Mendoza González, ENCB 23136. MEXICO. Quintana Roo, Punta Placer, 13 June 2014, J. A. Acosta Calderón, L. E. Mateo Cid, A. C. Mendoza González, ENCB 23135. MEXICO. Quintana Roo, Santa Rosa, 12 April 2015, J. A. Acosta Calderón, L. E. Mateo Cid, A. C. Mendoza González, ENCB 23134.

Geographic distribution: — Belize, Cuba, Haiti, Jamaica, Martinique, Mexico.

Habitat: — Rocky platforms with moderate surge and fresh water influence from mangroves. Subtidal to 1 m depth.

Comments:— Udotea fibrosa differs from the other species by the absence of lateral appendices in the siphons of the spatulate blade, lack of zonation, fibrous texture and shape of the stipe appendages. The diameters of stipe and blade siphons are smaller than those reported in specimens from Belize ( Littler & Littler 1990), Punta Brava, Quintana Roo, Mexico ( Collado-Vides et al. 2009) and Cuba ( Moreira et al. 2013). Littler & Littler (1990) mention that U. fibrosa has wider blade siphons than U. conglutinata and U. abbottiorum . In this study, the diameter of blade siphons between U. fibrosa and U. abbottiorum were relatively similar. Udotea fibrosa can be confused with U. cyathiformis f. sublittoralis since both have a coarse fibrous texture and spatulate blade, however, the blade of U. fibrosa lacks the zonation bands characteristically shown by U. cyathiformis f. sublittoralis . This species was uncommon in the study area and has been registered only for Puerto Morelos ( Collado-Vides et al. 2009), and Punta Xoquen in the Biosphere Reserve of Sian Ka’an, Mexico ( Acosta-Calderón et al. 2016).