Udotea cyathiformis Decaisne (1842: 106)

Rocha, Mayara C. B. S., Pereira, Sonia M. B., Oliveira-Carvalho, Maria F., Benko- Iseppon, Ana M., Ximenes, Caroline F., Fujii, Mutue T. & Cassano, Valéria, 2023, Morphological and molecular characterization of Udotea species (Bryopsidales, Chlorophyta) from northeastern Brazil with a new record of U. dotyi from the western south Atlantic, Phytotaxa 578 (1), pp. 57-74 : 64-65

Udotea cyathiformis Decaisne (1842: 106)

( Fig. 3–6 )

Type locality: Iles des Saintes , Guadeloupe, Lesser Antilles .

Description: Thallus erect, light to dark green, lightly calcified, growing isolated or in groups, up to 10.5 cm tall, attached to the substratum by a bulbous basal portion composed of a fibrous rhizoidal mass ( Fig. 3 ). Stipe short, flattened or cylindrical, up to 5.5 cm long and up to 4 mm wide. Transition between stipe and blade evident. Blade fibrous, cup-like, closed or partially fused to the stipe, multistratose to the margins, ecorticate, not thick, with visible concentric zonation, up to 5 cm long. Blade siphons without lateral appendages, cylindrical, dichotomously branched with symmetric constrictions above the dichotomies, 40–90 µm in diameter ( Fig. 4 ). Stipe siphons interwoven, longitudinally arranged, 40–110 µm in diameter, with lateral appendages often distributed irregularly to oppositely, sometimes unilateral on the siphons with constrictions at the base. Lateral appendages irregularly branched or dichotomous, appendages stalk 150–300 μm long, 40 μm in diameter; apices irregularly branched and terminating in asymmetrical dichotomies with swollen or flattened tips ( Figs 5, 6 ). Fertile specimens not found.

Habitat: Specimens have been found growing on sandy substrate in the intertidal zone or, more rarely, on rocks in calm areas.

Material examined: BRAZIL. Bahia: Porto Seguro , 16º26’59”S, 39º03’53”W, 16 January 2012, F Scherner ( SP400046 ). GenBank accession: rbc L OK623524 .

Additional material examined: BRAZIL. Pernambuco: Recife, 149 Station , 07°56’7’’S, 34°32’6’’W, Y . Ugadim ( SPF027703 ); Carne de Vaca , 34°49’50.78”S, 07°34’40.89”W, 16 September 1997, M. F . Oliveira-Carvalho ( PEUFR52745 ) Carne de Vaca , 34°49’50.78”S, 07°34’40.89”W, 11 November 1997, M. F . Oliveira-Carvalho ( PEUFR52746 ) .

Remarks: This taxon can be readily recognized by the cup-like blade, closed or partially fused to the stipe, blade ecorticate, and stipe siphons often with irregular to opposite appendages disposed on the siphons, appendages irregularly branched, dichotomous at the apices with swollen or flattened tips. Overall, our specimens are in accordance with the descriptions of U. cyathiformis by Littler & Littler (1990) and Acosta-Calderón et al. (2018). However, the cup-like blade of our specimens differs from those described as spatulate by Acosta-Calderón et al. (2018). Our specimens showed larger dimensions of the thallus (10.5 cm high vs. 4.5 cm high, Acosta-Calderón et al. 2018), length blade (5 cm vs. 2.9 cm, Acosta-Calderón et al. 2018), and stipe (5.5 cm x 4 mm vs. 13 mm x 2 mm, Acosta-Calderón et al. 2018). Also, anatomically our specimens showed greater measurements in the diameter of the blade siphons (40–90 µm in diam. vs. 45–55 μm in diam, Acosta-Calderón et al. 2018). Nevertheless, these morphological differences have no diagnostic value to separate species. Our specimen was found only in the intertidal zone, whereas specimens of ‘ U. ’ cyathiformis described by Santos & Nunes (2014) also from Bahia, Brazil occur from the intertidal to subtidal zones up to 45 m depth. Specimens from the Caribbean Sea ( Littler & Littler 1990) and Mexico ( Acosta-Calderón et al. 2018) occur only in subtidal zone, growing to 30 m depth, and to 2 m depth, respectively. Although our specimens fit into U. cyathiformis ( Table 3 ), our results with rbc L showed that the Brazilian material is a genetically distinct species from the authentic ‘ U ’. cyathiformis from the Caribbean Sea.

Figures

FIGURES 3–14. ‘Udotea cyathiformis’. 3. External morphology. 4. Detail of the blade siphon showing dichotomies with constrictions. 5–6. Detail of the stipe lateral appendages. Udotea dotyi. 7–9. Variation of external morphology.10. Blade siphon showing arrangement of lateral appendages. 11. Detail of the blade siphon showing unilateral appendages. 12. Detail of blade lateral appendages. 13–14. Details of the stipe lateral appendages.