Skip to main content

Service Notice

The Western Australian Herbarium’s collections management system and census were set to read-only mode on 1 October 2025. Taxonomic updates published since this time are not being reflected in Florabase, herbarium collections, or Western Australia’s taxonomic names census (Nomos). Conservation listings displayed on Florabase may also be out of date. Please refer to DBCA’s Threatened species and communities webpage for the most recent Threatened and Priority Flora List, noting that recent taxonomic updates are similarly not included. Our database migration is moving to a staging phase. We thank you for your patience as we ensure the integrity of our biodiversity data, develop new workflows, and train staff to use the new systems. Please reach out to us if you have any questions or concerns.

The notice period started at 12:00 pm on Wednesday, 1 October 2025 +08:00 and will end at 12:00 pm on Friday, 1 January 2027 +08:00.

Advanced Search

Antithamnion gracilentum (Harv.) J.Agardh

Reference
Acta Univ.Lund. Index p. 1 (1896)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus medium to dark red-brown, with branched prostrate axes bearing erect, opposite, distichous pinnae to 5 mm high, not entirely complanately branched, pinnae with 3–8 lower pairs of opposite lax, often diverging pinnules, alternate above. Attachment by branched multicellular processes with terminal haptera, arising from cells of prostrate axes; epiphytic (on Cystophora spp). Structure. Apical cells 7–9 µm in diameter and L/D 1–2, increasing to 130–180 µm in diameter and L/D 1–2(–3) in mature axial cells. Pinnae with a small isodiametric basal cell, cells of rachis 35–80 µm in diameter and L/D 1.5–2.5, decreasing in pinnules to 20–40 µm in diameter and L/D 1–2 several cells below their ends; gland cells on special 2–4-celled branches on the lower sides of pinnule cells, 2–4 cells from pinnule base. Lateral branches arising regularly and alternately usually at intervals of 3(–4) axial cells, directly from the axial cells. Cells uninucleate; rhodoplasts discoid, elongate in larger cells.

Reproduction. Gametophytes dioecious. Procarps with a 4–celled carpogonial branch borne on the basal cell (supporting cell) of successive pinnae. Post-fertilization fusions occur between the axial cell, supporting cell, and foot cell and upper cell from the auxiliary cell, and the upper cell forms the first gonimolobe 400–1000 µm across of carposporangia 40–70 µm in diameter; pinnae on axial cells below the carposporophyte enlarge and curve over the carposporophyte. Spermatangial heads occur on special branches on the adaxial side of lower cells of the pinnules, each head 35–55 µm in diameter and L/D 1–2, with an axis of 5–8 cells each bearing a whorl of 4 cells with terminal spermatangia. Tetrasporangia occur adaxially on basal (to third) cells of pinnules, sessile, ovoid, 45–90 µm in diameter, decussately or cruciately divided.

Distribution. Rottnest I., W. Aust., to Mowarry Point, N.S.W. and W Tas.

Habitat. Epiphytic on Cystophora species.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 100–104 (1998)]