Hydrolithon reinboldii

Tâmega, Frederico T. S., Riosmena-Rodriguez, Rafael, Mariath, Paula Spotorno-Oliveira Rodrigo, Khader, Samir & Figueiredo, Marcia A. O., 2015, Taxonomy and distribution of non-geniculate coralline red algae (Corallinales, Rhodophyta) on rocky reefs from Ilha Grande Bay, Brazil, Phytotaxa 192 (4), pp. 267-278 : 272-274

Hydrolithon reinboldii (Weber-van Bosse & Foslie) Foslie, 1909: 55

( Figs. 10–13 )

Basionym:— Lithophyllum reinboldii Weber-van Bosse & Foslie in Foslie, 1901b: 5.

Lectotype:— TRH ( A14-775 ), Siboga Expedition, Station 91, collection 38 ( Adey & Lebednik, 1967: 32).

Type locality:—Muaras Reef, East Kalimantan, Indonesia ( Silva et al. 1996: 239). This type locality was first recorded by Adey & Lebednik (1967: 32).

Isolectotypes:—L (991-239-240, 991-239-241), TRH (Siboga Expedition, Station 91, collection 57 [TRH A14-776], 74 [TRH A14-777]) ( Verheij & Woelkerling, 1992: 284–285).

Homotypic synonyms:— Goniolithon reinboldii (Weber-van Bosse & Foslie) Weber-van Bosse & Foslie, 1904: 49–51; Porolithon reinboldii (Weber-van Bosse & Foslie) Lemoine, 1911: 166–169; Spongites reinboldii (Weber-van Bosse & Foslie) Penrose & Woelkerling, 1988: 173.

Material examined:— BRAZIL. Rio de Janeiro State, Rochedo de São Pedro (23º03’43.74” S, 44º31’46.26” W, 30.x.2003, F. T. de S. Tâmega & M. A.de O. Figueiredo, RB 493708 ; RB 493709 ; RB 493710 ) .

Description:—Thalli non-geniculate, encrusting ( Fig. 10 ); 61–349 μm thick; internal construction dimerous with a unistratose hypothallus composed of non-pallisade cells; single layer of rounded, dark-staining epithallial cells ( Fig. 11 ) that measure 2–9 μm in length and 5–8 μm in diameter; subepithallial initials rectangular and measure 4–16 μm in length and 5–10 μm in diameter ( Fig. 11 ); perithallial cells square to rectangular and measure 4–15 μm in length and 4–17 μm in diameter; hypothallial cells square to rectangular and measure 3–19 μm length and 4–21 μm diameter. Cells of adjacent perithallial and hypothallial filaments joined by cell fusions ( Fig. 11 ); secondary pit connections not observed.

Gametangial thalli diocieous. Carpogonial conceptacles with chambers 117–199 μm in diameter and 80–95 μm in height. Spermatangial conceptacle with chambers 73–93 μm in diameter and 62–70 μm in height. Simple spermatangial systems are restricted to the conceptacle chamber floor.

Mature tetrasporangial conceptacles are uniporate and raised above the surrounding thallus surface ( Fig. 12 ); conceptacle roofs 4–6 cells thick ( Fig. 13 ); conceptacle pore canal lined by enlarged cells that are vertically orientated with the pore canal opening sunken slightly below the thallus surface; conceptacle external diameter 320–360 μm; chambers 102–255 μm in diameter and 101–184 μm in height. A central columella was not observed; mature zonately divided tetrasporangia measure 22–42 μm in length and 14–36 μm in diameter; the conceptacle floor located 10–13 cells below thallus surface ( Fig. 13 ).

Remarks:—Specimens ascribed to H. reinboldii in this study show similarities in their tetrasporangial conceptacle characteristics with those previously reported for the species in Australia (Ringeltube & Harvey 2000), Borneo ( Penrose & Woelkerling 1988), Hawaii ( Adey et al. 1982), Indonesia ( Verheij 1994) and Mexico ( Mendoza-Gonzalez et al. 2009) ( Table 3). However, greater variation in the ranges of measured characteristics exists amongst these different populations and further investigations will be required to ascertain the species’ delimitations.

Ecological observations:—The species is found growing epilithically on rocks and epizoically on mollusk shells in the intertidal zone and subtidally down to 4 m depth.

Geographical distribution:—The species has been widely reported from the Atlantic, Indian and Pacific oceans. See Guiry & Guiry (2014) for a detailed distribution list.

Distribution within the study sites:—Rochedo de São Pedro (23º03’43.74” S, 44º31’46.26” W).

Figures

FIGURE 10–13. Hydrolithon reinboldii. FIGURE 10. External morphology (RB 493708). Scale bar = 1 cm. FIGURE 11. Longitudinal section showing a single layer of rounded epithallial cells (e), subepithallial initials (s) and cell fusions between adjacent filaments (white arrow) (RB 493709) Scale bar = 100 μm. FIGURE 12. Magnified view of a tetrasporangial conceptacle roof showing the enlarged cells (E, white arrow) lining the pore canal and the pore canal opening sunken slightly below the thallus surface (black arrow) (RB 493709). Scale bar = 10 μm. FIGURE 13. Longitudinal section through a tetrasporangial conceptacle showing zonately divided tetrasporangia (te) (RB 493709). Scale bar = 50 μm.