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Melanothamnus sphaerocarpus (Børgesen) Díaz-Tapia & Maggs

Reference
Eur.J.Phycol. 52:9 (2017)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus mostly erect from a limited prostrate system, pale red. Prostrate axes 150–180 µm diam. [segment L:B c. 1], attached to the substratum by unicellular rhizoids cut off from pericentral cells. Erect axes to 10 mm tall, subdichotomously branched, to 250 µm diam. near the base and tapering to c. 50–60 µm diam. near apices. Segments near apices with L:B < 1, becoming more elongate in mid-regions, then L:B c. 0.5 near the base. Structure with 4 pericentral cells and 1 trichoblast or scar cell per segment, these borne in a spiral pattern. Trichoblasts dichotomously divided, prominent near the apices but soon dehiscent.

Reproduction. Spermatangia formed in heads on lower branches of trichoblasts, 150–220 µm long, 45–60 µm wide, with a sterile tip. Cystocarps lateral, spherical, 250–280 µm diam. Tetrasporangia spirally arranged in upper branches, in series of up to 10 sporangia, but only the proximal 3 or 4 mature, 50–60 µm diam., slightly distorting the segments.

Distribution. Widely distributed in tropical seas.

Habitat. Epiphytic or epilithic.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 549 (2018)]