Chondria collinsiana Howe 1920

Chondria collinsiana (Figs 1 C–J)

Thallus erect, cylindrical, delicate, of soft consistency, 2.5–4.0 cm high, brownish, fixed to the substrate by a discoid holdfast and rhizoids along the basal region of the thallus, presence of anastomoses in the basal region of the thallus. Ramification radial, dense, with 3–4 orders of branches. Branches of the last order with constricted bases, apices truncated and with a slight apical depression. The basal region of the principal axis is (580–)610(–640) µm in diameter; the median region (500–)540(–600) µm in diameter; and the apical region (300–)360(–430) µm in diameter. First order branches 500–530 µm in diameter; second order branches 300– 460 µm in diameter; and third order branches 120–330 µm in diameter. Trichoblasts present on the apices of truncated branches. Trichoblast scars frequent at the distal region of the thallus. Thallus with polysiphonic organization; transversal cuts show 5 periaxial cells (75.0–)78.0(–112.5) µm long and 62.5–80.0 µm in diameter, with lenticular thickening and wrapped by 3 layers of medullar cells, colorless, (30–)48(–62) µm in diameter; cortical region with 1 layer of pigmented cells, (10–)13(–20) µm in diameter. In surface view, cortical cells elongated, (70.0–)100.0(–112.5) µm long and 17–22 µm in diameter, with pit connections between the cells. Cistocarps spherical to ovoid, not adnate, 0.5–1.0 mm long and 0.5 mm in diameter, growing on the last branchlets, with protuberance at base. Spermatangial bodies laminar, discoid, (210–)250(– 330) µm in diameter, with rounded spermacia, wrapped in 1 layer of sterile and rectangular cells, 3–5 on the apices branches and branchlets. Tetrasporangia formed from the pericentral cells on the branchlets; in transversal section, 3–5 tetrahedral tetrasporangia, 60–80 µm in diameter.

Representative specimens examined:— BRAZIL. Bahia: Ilha de Itaparica, Vera Cruz, Praia da Penha, 18/ III/2007, Moura (HUEFS 130885); 14/VII/2007, Alves & Peixoto (HUEFS 130887). Praia da Barra Grande, 19/III/2007, Santos (HUEFS 147560); 18/V/2007, Santos (HUEFS 147561); 14/VII/2007, Santos (HUEFS 147562); 27/IX/2007, Oliveira & Oliveira (HUEFS 130890).

Geographic distribution along the west coast of Atlantic Ocean:—Florida, Bahamas, Belize, Cuba, Venezuela, Brazil (Taylor 1960, Ganesan 1989, Littler et al. 1995, Littler & Littler 2000, Bacci 2005, Suárez 2005, Ribeiro 2008).

Comments:— Chondria collinsiana is restricted to the Caribbean Sea, the South Atlantic, and the Indian Ocean (Jaasund 1976, Littler et al. 1995, Bacci 2005, Ribeiro 2008). Along the Brazilian coast this species was previously known only from the states of Espírito Santo (Bacci 2005) and Rio de Janeiro (Ribeiro 2008). The present study expanded the distribution of this species to the northeastern coast of Brazil.

The specimens analyzed are in agreement with the characteristics described and illustrated by Littler et al. (1995) and Bacci (2005). According to Bacci (2005), this species differs from the others along the coast of the states of Espírito Santo and São Paulo by having an erect thallus, delicate, densely radially branched, slight depressions at the apices of the branches and branchlets, and by the presence of lenticular thickenings on the medullar cell walls.

In addition to these morphological characteristics, the shapes of the sterile cells of the spermatangial bodies and the characteristics of the cistocarp are useful in identifying species of C hondria C.Agardh (Bacci 2005). This is the first report of masculine gametophytes of this species from the Brazilian coast. They were described earlier by Littler et al. (1995) for the flora of Belize. The spermatangial bodies of Chondria collinsiana are laminar, discoidal, with rounded spermacia, surrounded by a layer of rectangular sterile cells, as can be seen in Fig. 1I. Thalli were observed growing isolated on the thallus of A. crenulata, sometimes forming dense tufts when attachments are present in the basal region of the thallus.