Electronic Flora of South Australia Species Fact Sheet

Lesueuria minderiana Woelkerling & Ducker 1987: 193, figs 1–24.

Phylum Rhodophyta – Class Florideophyceae – Order Corallinales – Family Corallinaceae – Subfamily Mastophoroideae

Selected citations: Woelkerling 1988: 123, figs 106–110.

Thallus largely unconsolidated, mostly 0.1–0.4 mm in greatest extent, vegetative portions endophytic but conceptacles produced externally to the host. Structure filamentous to partly pseudoparenchymatous; construction diffuse, consisting of simple or branched, laterally cohering, filaments with cells mostly 7–16 µm in diameter and 8–30 µm long; cell elongation characteristics uncertain; cells of adjacent filaments joined by cell-fusions, secondary pit-connections absent; epithallial cells mostly 8–11 µm in diameter and 5–11 µm long, absent from vegetative portions of thallus but terminating most conceptacle roof filaments, with distal walls rounded or flattened but not flared; haustoria occasional, penetrating cells of host; trichocytes unknown.

Reproduction: Vegetative reproduction unknown. Gametangia, carposporangia and tetrasporangia formed in uniporate conceptacles produced externally to the host. Bisporangia unknown.

Gametangial thalli probably dioecious. Carpogonia terminating 2- or 3-celled filaments arising from the female conceptacle chamber floor. Mature female-carposporangial conceptacle roofs protruding above the host surface, 40–70 µm thick, composed of 3–7 layers of cells above the chamber, conceptacle chambers 60–150 µm in diameter and 50–70 µm high. Carposporophytes developing within female conceptacles after karyogamy, mature carposporophytes composed of a conspicuous central fusion cell and several-celled gonimoblast filaments bearing terminal carposporangia 19–27 µm in diameter. Spermatangial filaments unbranched, arising from the floor of male conceptacle chambers, mature male conceptacle roofs protruding above the host surface, 30–65 µm thick, composed of 3–7 layers of cells above the chamber, conceptacle chambers 90–110 µm in diameter and 35–60 µm high.

Tetrasporangial conceptacle roofs protruding above the host surface, 40–80 µm thick above the chamber and composed of 3–7 layers of cells, conceptacle chambers 100–190 µm in diameter and 65–115 µm high; tetrasporangia peripheral to a central columella, each mature sporangium 15–25 µm in diameter and 35–50 µm long, containing four zonately arranged tetraspores.

Type from Mabel Cove, Rottnest I., W.Aust., 0–1 m deep (Woelkerling, 9.ii.1978); holotype in LTB (10851); depicted, in part, in Woelkerling & Ducker (1987, figs 1–24).

Selected specimens: Kalbarri, W. Aust., 1–2 m deep (Woelkerling, 22.ii.1978; LTB, 10819). Flat Rocks, W. Aust., drift (Woelkerling, 25.ii.1978; LTB, 10769). North Point Reef, Rottnest I., W. Aust., 1–2 m deep (Woelkerling, 10.ii.1978; LTB, 10760). Sarge Bay, Cape Leeuwin, W. Aust. (Parsons, 16.xi.1968; AD, A56880). Point Malcolm, SW of Israelite Bay, W. Aust., 0–2 m deep (Woelkerling, Platt & Jones, 7.ii.1984; LTB, 14203). Eucla, W. Aust. (Womersley, 2.ii.1954; AD, A56884). Wilson Bluff, S. Aust., drift (Woelkerling, 26.i.1978; LTB, 10814). Tiparra Reef, Spencer Gulf, S. Aust. (Shepherd, 20.viii.1971; AD, A56881). Vivonne Bay, Kangaroo I., S. Aust., upper sublittoral (Woelkerling, 23.ii.1979; LTB, 11650). Urquhart Bluff, Vic., drift (Woelkerling & Woelkerling, 22.i.1986; LTB, 15318).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Kalbarri, W. Aust., to Urquhart Bluff, Vic.

Taxonomic notes: Lesueuria minderiana has been found only on genicula of Metagoniolithon chara growing in tide pools and to depths of 8 m. Specimens are most easily detected by examining host genicula with a stereomicroscope; the conceptacles of Lesueuria minderiana commonly occur in small clusters and are readily recognised. Gametangial and tetrasporangial thalli usually occur within single populations.

References:

WOELKERLING, W.J. & DUCKER, S.C. (1987). Lesueuria minderiana gen. et sp. nov. (Corallinaceae, Rhodophyta) from southern and Western Australia. Phycologia 26, 192–204.

WOELKERLING, Wm.J. (1988). The Coralline Red Algae. [British Museum (N.H.): London.]

The Marine Benthic Flora of Southern Australia Part IIIB complete list of references.

Author: W.J. Woelkerling (with some genera by D.L. Penrose)

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustrations in Womersley Part IIIA, 1996: FIGS 62G, 106, 107.

Figure 62   enlarge

Fig. 62. Thallus construction in non-geniculate Corallinales (A, LTB, 12831; B, LTB, 11719; C, LTB, 13268; D, LTB, 13188; E, LTB, 13703; F, LTB, 12937; G, LTB, 10851). A. Monomerous construction in a longitudinal section of an encrusting plant of Mesophyllum macroblastum. B. Monomerous construction in both longitudinal (L) and transverse (T) views in a fracture of an encrusting plant of Mesophyllum incisum. Note difference in appearance in thallus construction in the two planes of view. C. Dimerous construction in a longitudinal section of Melobesia rosanoffii.

Figure 106   enlarge

Fig. 106. Lesueuria minderiana (A, B, D, LTB, 10851; C, LTB, 10760). A. Surface view of thallus showing conceptacles (arrows) protruding from surface of host geniculum of Metagoniolithon. Vegetative portion of thallus is endophytic. B. Section of host geniculum showing endophytic, diffuse thallus of Lesueuria minderiana. C. Haustorium (H) of L. minderiana penetrating host cell. D. Portion of roof of a tetrasporangial conceptacle showing terminal epithallial cells. Epithallial cells have not been found on vegetative filaments.

Figure 107   enlarge

Fig. 107. Lesueuria minderiana (A, C, D, LTB, 10851; B, LTB, 10760). A. Section of most of a mature tetrasporangial conceptacle. B. Section of part of a female-carposporangial conceptacle with mature carpogonial filaments. C. Section of part of a female-carposporangial conceptacle with mature carposporophyte; g = gonimoblast filament; C = carposporangium. D. Section of most of a male conceptacle with unbranched spermatangial filaments arising from chamber floor.

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