Cartilaginous, cylindrical to compressed, brow-red to blackish purple fronds, to 75 mm high, from an expanded discoid base. Repeatedly dichotomous, fastigiate, with rounded, somewhat flattened apices.

Similar species: Polyides rotundus from which it many be distinguished by the presence of a rhizoidal base, narrower branching angles (i.e. less fan-shaped), and that the fronds are brownish when held up to the light.

Original publication: Martius, C.F.P. von (1833). Flora brasiliensis seu enumeratio plantarum in Brasilia tam sua sponte quam accedente cultura provenientium, quas in itinere auspiciis Maximiliani Josephi I. Bavariae regis annis 1817-1820 peracto collegit, partim descripsit; alias a Maximiliano seren. principe Widensi, Sellovio aliisque advectas addidit, communibus amicorurn propriisque studiis studii methodum naturalem dispositas et illustratas edidit C. F. Ph. de Martius.... Vol. 1(1) pp. [i]-iv, [1]-390. Stuttgartiae et Turbingae: sumptibus J.G. Cottae.

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Braune, W. (2008). Meeresalgen. Ein Farbbildführer zu den verbreiteten benthischen Grün- Braun- und Rotalgen der Weltmeere. pp. [1]-596, 266 pls. Ruggell: A.R.G. Gantner Verlag.

Dawes, C.J. & Mathieson, A.C. (2008). The seaweeds of Florida. pp. [i]- viii, [1]-591, [592], pls I-LI. Gainesville, Florida: University Press of Florida.

Dixon, P.S. & Irvine, L.M. (1977). Seaweeds of the British Isles. Volume 1. Rhodophyta. Part 1. Introduction, Nemaliales, Gigartinales. pp. xi + 252, 90 figs. London: British Museum (Natural History).

Lewis, J.A. & Womersley, H.B.S. (1994). Family Phyllophoraceae Nägeli 1847: 248. In: The marine benthic flora of Southern Australia. Part III A. (Womersley, H.B.S. Eds), pp. 259-270. Canberra: Australian Biological Resources Study.

Type species: This is the type species (holotype) of the genus Gymnogongrus. 

Basionym: Fucus griffithsiae Turner

Type locality: Chit Rocks, Sidmouth, Devon, England (Turner 1802: pl. 37).

Lectotype: BM-K (Turner 1802: pl. 37).

Notes: Devon (probably near Chit Rock, Sidmouth (Dixon & Irvine 1977: 219).