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"Lageneschara gen. nov.
Colony developed from an encrusting sheet, forming erect, folded, unilaminar plates ; frequently enrolled or overlapped basally to give irregular bilaminar portions. Frontal wall of autozooid with proximal cryptocystidean portion, perforated by small stellate pores, and a more extensive distal umbonuloid shield, devoid of pores. Aperture produced as a prominent, thickened peristomial tube, with a broad, sharp cornered lyrula at its base, just above the frontal membrane. Ovicell prominent, spherical, imperforate ; not closed by autozooidal operculum. No spines or avicularia. Ancestrula tatiform.
Type species : Phylactella lyrulata Calvet, 1909.
Phylactella lyrulata Calvet (Fig. 2A, B) is a distinctive species which has been well described and illustrated by both Livingstone (1928) and Rogick (1957). However, its systematic placing has always been unsatisfactory. It differs from all other species within the Phylactellidae in the structure of the orifice and ovicell, and, more fundamentally, in the ontogeny of the frontal wall of the autozooid, which in P lyrulata is quite clearly umbonuloid. It bears a superficial resemblance to species of Escharella Gray, but in that genus frontal wall ontogeny is entirely cryptocystidean. Gordon (1984) instituted the new genus Elleschara, within the Umbonulidae, for Lepralia bensoni Brown, another problematic species in which some features of Escharella are combined with umbonuloid frontal wall ontogeny. P lyrulata differs from Elleschara bensoni in lacking spines and in the form of the aperture, which in the latter is developed as a peristomial tube with an inner ridge on its proximal side, modified basally as a lyrula-like structure. Finally, unlike P lyrulata, E. bensoni has well developed basal pore chambers.
Lageneschara lyrulata (Calvet) has been reported from numerous Antarctic localities, from Marguerite Bay, Graham Land (Rogick 1955), eastwards to Queen Mary Land (Livingstone 1928), and the Ross Sea (Rogick 1955). The extensive series of samples from the National Antarctic Expedition and the British Antarctic Expedition were all from the Ross Sea, and a single specimen from "Discovery" Investigations (stn. 164) originated from the South Orkneys. L. lyrulata has not been recorded from beyond Antarctic shelf waters, and may be considered to be an endemic species." (Hayward and Thorpe, 1988b: 282)
Marguerite Bay, Graham Land ; Queen Mary Land; Ross Sea; South Orkneys
- Lageneschara lyrulata Species