456 
Telopea 8(4): 200q 
Taxonomy 
Actinotus periculosus Henwood, sp. nov. 
Actinotus helianthi Labill. et A. schwarzii F. Muell affinis. A. helianthi foliis magis penitu s 
et subtiliter dissectis, collis longioribus differt. A. schwarzii foliis majoribus stipellis 
basalibus destitutus, collis brev'ioribus, petalis filamentosis differt. 
Type: Queensland: Leichhardt District: 15 km N of 'The Tombs' on Marlong Creek, 
Mt Moffat region of Carnarvon National Park, M.J. Henwood 511, 19 Oct 1998 (holo 
SYD; iso BRI, NSW). 
Plants andromonoecious, erect to ascending, perennial, to 20-50 cm high. Stems 
branching, covered in dense white felted indumentum. Leaves cauline, discolorous, 
alternate, temately dissected, petiolate. Sheaths 6-9 mm long, sericeous and felted. 
Petioles 15-54 mm long, adaxially grooved. Laminas 20-100 mm long, 15-70 mm 
wide, finely dissected. Primary segments elliptic to linear, (20-)30-65 long, 1—5(—6) mm 
wide, apices acute or obtuse. Umbels capitulum-like, pseudanthial, borne in 
monochasial cymes, subtended by trifid bracts. Peduncles 30-90 mm long. Umbels 
15-30 mm in diameter, 94-310 flowered. Involucral bracts 9-12, apparently arranged 
in a single whorl; 25-55 mm long, 5-16 mm wide; lamina hairy, white with green tips, 
venation distinct. Bisexual flowers borne centrally in 'capitula' and surrounded by a 
peripheral ring (or rings) of male flowers. Anthesis proceeds centrifugally in each 
umbel. Bisexual flowers protandrous. Pedicels 4-4.5 mm long, articulated at junction 
with the gynophore, sparsely villous. Gynophores 3.4-4 mm long, villous. Sepals 
conspicuous, petaloid, ovate, 1—1.5 mm long, 0.5-0.75 mm wide, white to cream, bases 
truncate, apices acute, villous. Petals inconspicuous, filamentous, 0.8-0.95 mm long, 
glabrous. Stamens 5; filaments 1.7-2.5 mm long; anthers dorsifixed, 0.4-0.5 mm long' 
Stylopodia 0.5-0.9 mm high, glabrous. Nectaries 2, each a horn-like projection inserted 
directly below each style, 0.3 mm long, dark purple, glabrous. Ovaries unilocular, 
villous, surmounted by a column; column 2.4-3 mm long, villous. Styles 2, arranged' 
parallel to the plane of ovary compression, 1.4-2 mm long. Male flowers characterised 
by a much reduced (non-functional) gynoecium, otherwise similar to bisexual flowers 
Mature fruit not seen. (Fig. 1). 
Distribution and habitat: endemic to the Leichhardt District of Queensland 
Restricted to sandstone cliff faces (Fig. 2). 
Notes: The characteristically deeply dissected leaves with narrow, linear segments of 
A. periculosus do not correspond to either the woodland or the heath leaf forms of 
A. helianthi. Individuals of A. periculosus are further separable from A. helianthi by the 
former's longer gynoecial columns (2.4-3.0 mm long). Based on observations from one 
flowering season, A. helianthi and A. periculosus appear to be reproductively isolated 
when in sympatry — for example at Spyglass Mountain, in the Salvator Rosa region 
ot Carnarvon National. In such localities A. helianthi is fruiting whilst A. periculosus is 
at early anthesis. 
Actinotus periculosus is likewise easily separable from A. schwarzii. Like A. helianthi 
leaves of A periculosus lack the pair of basal basiscopic, stipel-like lobes that 
2t ra lT S , e ! he l f aves J oM - schwarzii. In addition, the length of the gynoecial columns 
ot both A helianthi and A. periculosus are not as long as those of A. schwarzii (> 3 0 mm 
m Sot Pet f °! A schwarzii are a P icall y broader than those of the other species 
1 owell (1992) and others have erroneously described A. helianthi as apetalous). Given 
e apparent reproductive isolation of A. periculosus from A. helianthi when in 
sympatry, combined with obvious differences in reproductive and vegetative 
A°heUanth P *“ ^ A periculosus does ' in fact ' warrant formal segregation from 
