Botryocladia franciscana J. A. S. Santiago, P. B. M. Carneiro, A. P. Santiago, R. G. Feijó & R. Maggioni, 2016

Santiago, Janaína De Araújo Sousa, Carneiro, Pedro Bastos De Macedo, Santiago, André Prata, Feijó, Rubens Galdino & Maggioni, Rodrigo, 2016, A New Species of Rhodymeniaceae (Rhodophyta, Rhodymeniales) from the Northern Brazilian Coast: Botryocladia franciscana sp. nov., Phytotaxa 243 (2), pp. 137-146 : 140-141

Botryocladia franciscana J. A. S. Santiago, P. B. M. Carneiro, A. P. Santiago, R. G. Feijó & R. Maggioni , sp. nov. ( Figs. 1 , 2 )

Type:— BRAZIL, Piauí: Luis Correia, Praia do Coqueiro, Parnaíba River Delta ; 2 o 53’52.20”S, 41 o 34’20.82”W, 26 April 2013, J.A.S. Santiago and A.P. Santiago. (holotype: HMAR 2594 !, female gametophyte). Molecular vouchers: rbc L (GenBank no. KR866021 ), cox 1 (GenBank no. KR011965 ) and UPA (GenBank no. KR872421 ) .

Paratype:— BRAZIL, Piauí: Luis Correia, Praia do Coqueiro, Parnaíba River Delta ; 2 o 53’31.82”S, 41 o 33’28.63”W, 26 April 2013, J.A.S. Santiago and A.P. Santiago. ( HMAR 2452 !, HMAR 2453 ! infertile) .

Etymology:—This species is named in honour of Prof. Francisca Pinheiro Joventino, professor and researcher at the Institute of Marine Sciences (LABOMAR), for her contribution as one of the founders of the institute and for her pioneering research on taxonomy of marine macroalgae in the state of Ceará.

Description:—Plants erect, brownish red in colour, 60–74 mm tall; stipes solid, terete and subterete, branched, 1000–1400 μm in diameter ( Fig. 1A ); attached by small discoid holdfasts, giving rise to stipes bearing many vesicles; vesicles spherical, obovoid and often elongating ( Fig. 1B ), 2.5–5 mm wide and 8–12 mm long, with complete cortication of vesicle wall ( Fig. 1D ); in transverse section, the vesicle walls consist of three (to four) cell layers ( Fig. 2B ); innermost cells of the medulla in surface view with large and small polygonal cells intermingled ( Fig. 2C ); gland cells obovoid to pyriform, 10–19 μm wide and 14–30 μm long, produced from inner medullary cells, which project into the vesicle cavity ( Fig. 2B ); 1–7 gland cells per supporting cell ( Fig. 2A ); cystocarps forming in upper portions of the vesicles wall, 700–1000 μm wide ( Fig. 2D ). The morphological and anatomical features of the paratype match the descriptions above, except for the cystocarp. Morphological characteristics of B. franciscana and similar species are summarized in Table 2 .

DNA sequences:—Partial sequences of the target genes were obtained only from the holotype. A sequence of 775 bp was obtained for rbc L (GenBank no. KR866021), a sequence of 650 bp for cox 1 (GenBank no. KR011965) and a sequence of 369 for UPA (GenBank no. KR872421). All sequences showed high homology to the corresponding sequences of other Botryocladia species, as revealed by searches with BLAST ( Altschul et al. 1990). The mean sequence divergence observed between B. franciscana and B. occidentalis and B. pyriformis , was 9.19% and 9.93%, respectively, for rbc L. B. occidentalis and B. pyriformis are two of the three Botryocladia species reported for the Brazilian coast.

Phylogenetic results:—Phylogenetic analyses of rbc L sequences included the species found on the Brazilian coast and 14 Botryocladia species found worldwide. The B. franciscana rbc L sequence was consistently resolved in a separate clade with high support, both in BI and ML analyses ( Fig. 3 ). One highly supported clade grouped Brazilian and Caribbean species: B. bermudana Schneider & Lane (2008: 615) , B. caraibica Gavio & Fredericq (2003: 95) and B. franciscana . However, B. occidentalis , which is found in Brazil as well, was placed in a different clade. The NJ analysis of rbc L sequences showed considerable interspecific divergence between B. franciscana and other Botryocladia species ( Fig. 3 ). In some instances, the pairwise distance is far higher than those found between accepted species. As observed in BI and ML trees, the NJ rbc L tree clustered B. franciscana with morphologically similar B. caraibica and B. bermudana . The sequences presented here for cox 1 and UPA could be compared only to a small number of recorded Botryocladia species. For cox 1, the sequence divergence observed between B. franciscana and B. pseudodichotoma (Farlow) Kylin (1931: 18) and B. skottsbergii (Børgesen) Levring (1941: 645) was 10.7% and 11.6%, respectively. For UPA, divergence values of 4.4% and 4.1% were found between B. franciscana and sequences from two B. skottsbergii .

Figures

FIGURE 1. Morphology and anatomy of Botryocladia franciscana. A, habit of holotype, scale bar 1 cm; B, example of elongated vesicles located at the apex of the thallus, scale bar 10 mm; C, cross-section of stipe showing medullary cells decreasing in size outwards, scale bar 200 μm; D, external cortex of the vesicle wall, in surface view, showing the cortication pattern, scale bar 100 μm. All photos by Janaina A. S. Santiago.

FIGURE 2. Anatomical features of Botryocladia franciscana holotype. A, inner surface of vesicle wall showing a medullary cell with seven secretory cells (arrow), scale bar 50 μm; B, cross-section of vesicle wall showing the number of cell layers and secretory cells (arrow), scale bar 50 μm; C, inner medulla of vesicle wall, surface view showing the polygonal cells, scale bar 100 μm; D, cross-section through a cystocarp protruding both inwardly and outwardly from the vesicle wall, scale bar 50 μm. All photos by Janaina A. S. Santiago.

FIGURE 3. ML tree topology based on rbcL sequences, with branch support from NJ, ML and BI analyses, respectively. ML and BI trees calculated using the GTR + Γ evolution model. ML and NJ support values are relative to 2,000 and 10,000 replicates, respectively (<50 not shown). BI support values are posterior probabilities (<0.5 not shown). GenBank accession numbers for all sequences are shown.