Early Cretaceous macrofloras 
23 
1986 Megasporangia of Isoetes; White; p. 169; figure 
260. 
1993 Isoetites elegans; McLoughlin and Guppy; p. 
14; figure 12. 
Holotype 
UWA16687; Leederville Formation (Neocomian- 
Barremian), Perth Basin, Western Australia 
(Walkom 1944). 
Material 
UWA16682, UWA16683 (principal sporangia- 
bearing specimen), UWA16684, UVVA16685, 
UWA16687 (principal foliage-bearing specimen), 
UWA16690, UWA16703, UWA16711. Counterparts 
of some specimens are held in the Australian 
Museum (AMF39815: see White 1986, figure 260). 
Distribution 
Leederville Formation (Neocomian-Barremian), 
Perth Basin, Western Australia. Previous 
assignation of these specimens to the Jurassic 
(Walkom 1944; Ash and Pigg 1991) is now deemed 
erroneous. 
Description 
Numerous (>30) radiating linear leaves, reaching 
at least 10 cm long, 5 mm wide, bases not 
preserved, apices pointed, margins entire (Figure 
3A). Longitudinal striae evident on some leaves but 
venation otherwise indistinct. Associated 
megasporophylls on type locality slabs bear 
clusters of numerous (>30) trilete megaspores. 
Megasporophylls identical to sterile leaves, 
showing no expansion around sporangia. 
Megasporangia reach 10 mm long, 2.5 mm wide 
(Figure 3C). Megaspores 0.5 mm in diameter, 
circular in polar compression, laesurae prominent; 
contact surfaces extending almost to the equator, 
laevigate; distal surface reticulate (moulds coarsely 
granulate: Figure 3D). Associated 
microsporophylls bear elliptical microsporangia, 10 
mm long, 3 mm wide, consisting of densely matted 
casts of ill-defined microspores (Figures 3E,F). 
Comments 
Although the earliest records of Isoetites are from 
the Upper Triassic (Bock 1962), they underwent a 
phase of global diversification during the Early 
Cretaceous (Pigg 1992). Ash and Pigg (1991) listed 
the fossil species previously assigned to Isoetites 
Munster 1842 and Isoetes Linnaeus 1753. All 
examples essentially consist of linear leaves or 
sporophylls either in isolation or attached in 
rosettes to short cylindrical or spherical corms. 
Other species can be distinguished from /. elegans 
by possession of serrate leaf margins (Isoetites 
serratus Brown, 1939, Isoetites serratifolius Bose and 
Roy, 1964), air channels within the leaves ( Isoetites 
horridus (Dawson) Brown, 1939), the details of 
megaspores and cuticle ( Isoetites choffati Saporta, 
1894, Isoetes reticulata Hill, 1987), leaf proportions 
(Isoetites gramineoides Bock, 1962, Isoetites rolandii 
Ash and Pigg, 1991), and corm dimensions ( Isoetites 
crociformis Munster, 1842, Isoetites circularis 
(Emmons) Brown, 1958). 
Isoetes janaianus Banerji, 1989 from the Middle to 
Upper Jurassic of India has similar leaves and 
sporangia to I. elegans but is characterized by a 5- 
lobed rhizomorph whereas corms are not yet 
available for the latter species. Isoetites bulbiformis 
Drinnan and Chambers, 1986 from the Victorian 
Lower Cretaceous, distinguished by its smaller size 
and expanded leaf tips, may represent 
gymnospermous remains. The Indian Lower 
Cretaceous Isoetites indicus Bose and Roy, 1964, 
although represented only by sporophyll bases, is 
characterized by its smaller but more numerous 
megaspores in each sporangia (Bose and Banerji 
1984). 
Genus Nathorstianella Glaessner and Rao, 1955 
Type species 
Nathorstianella babbagensis (Woodward) Glaessner 
and Rao, 1955; Lower Cretaceous; Mt Babbage, 
South Australia. 
Nathorstianella babbagensis (Woodward) 
Glaessner and Rao, 1955 
Figure 3B 
cf. 1961 "fragment of stem" White; p. 304; plate 6, 
figure 3. [1961a]. 
Holotype 
F15070 (Adelaide University Geology 
Department); Algebuckina Sandstone 
(Neocomian); Mt Babbage, South Australia 
(Glaessner and Rao 1955). 
Material 
WAM P.88.2, WAM P.96.12. 
Distribution 
Algebuckina Sandstone (Berriasian-early 
Valanginian), Eromanga Basin, South Australia 
(Dettmann et al. 1992); Broome Sandstone 
(Neocomian-Barremian), Canning Basin, Western 
Australia (this study). 
Description 
Fragmentary casts of cylindrical axes (14-17 mm 
wide, 24-35 mm long) bearing numerous spirally 
arranged leaf or root scars (Figure 3B). Scars 
diminutive (0.5 mm wide, 0.25 mm high), c. 0.5-1 
