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Taxonomy
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Type: western edge of Mt Zero-Taravale Wildlife Sanctuary, c. 16.8 km W of Taravale Homestead, accesses via Laroona Ewan Rd, Queensland, 23 Mar. 2014, R. Jensen 3116 (holo: BRI-AQ856790; iso: CANB, PERTH).
Hibbertia sp. Taravale (J.E. Kemp+ 20074), Queensland Herbarium.
Fig. 2. Hibbertia advena. A flower; B young fruit. Photos: R. Jensen.
Erect much-branched shrubs 0.8–1.5 m high, the branches becoming rigid-woody; young stems glabrous; intrapetiolar tufts of hairs to c. 1 mm long. Leaves widely spreading, scattered, linear, (7–) 10–20 (–25) mm long, 0.7–1.2 mm wide; base flattened, gradually constricted to a glabrous petiole 0.4–1.6 mm long; margins strongly revolute, butting tightly against the prominent abaxial midrib (thus completely obscuring the true abaxial surface); adaxial surface ± smooth or slightly tuberculate especially on the leaf edges, convex, glabrescent with very sparse antrorse simple hairs on very slight tubercles, sometimes also with finer hairs without tubercles especially near the base; abaxial surface with the midrib usually flush with the margins or occasionally slightly receded or bulging, accounting for c. 50% of the leaf width, with a distinct groove either side formed from the revolute margins, the surfaces of the groove distinctly tuberculate, the true abaxial surface (only visible by dissection) densely tomentose; apex with a straight, pungent point to 1.2 mm long formed from the excurrent midrib. Flowers single, terminal on lateral branches, on glabrous pedicels 0.8–1.7 mm long that elongate and somewhat recurve in fruit; primary bract at the base of the pedicel, narrowly linear-triangular, 2.2–3.8 mm long, 0.2–0.5 mm wide, pungent, entire, glabrous; secondary bracts few, triangular with sheathing bases, usually slightly larger than the primary bract. Sepals unequal, glabrous; midribs not prominent; outer sepals broadly lanceolate, 6.8–7.1 mm long, 3–3.2 mm wide, somewhat verrucose, with membranous margins and acute apex; inner sepals oblong-elliptic to oblong-obovate, 7.2–7.5 mm long, 4.2–4.5 mm wide, obtuse to rounded and ± mucronate. Petals yellow, obovate, c. 8 mm long, emarginate. Stamens (14)15, in 5 distinct groups of usually 3 stamens alternating with the carpels; filaments scarcely connate basally, 0.6–1.5 mm long; anthers obloid, 1.4–2.2 mm long, dehiscing by introrse, longitudinal slits, connivent; staminodes absent. Carpels 5; ovaries obovoid to compressed-globular, glabrous; styles 4–5 mm long, spreading widely from their insertions on the upper, outer ovary surface then curving upwards, with the stigmas placed above the anthers. Ovules 2 per carpel (rarely 1 by abortion). Seeds glossy, dark brown to black, to c. 2.5 mm long; aril membranous, covering basal half of seed. Fig. 2.
Additional specimens examined. Queensland: 18 km N of Old Greenvale Railway, 2 Jan. 1999, R.J. Cumming 18259 (BRI); Mt Zero property, tributary of Running River Creek, 31 May 2003, R.J. Cumming 21515 (BRI); Mount Zero property, tributary of Running River Creek, 24 Mar. 2004, R.J. Cumming 22098 (JCT); western edge of Mt Zero/Taravale Wildlife Sanctuary, c. 16.8 km W of Taravale Homestead, accesses via Laroona Ewan Rd, 23 Mar. 2014, R. Jensen 3110 (BRI); approximately 1.1 km E of the Laroona Ewan Road and 680 m N of minor track, on Mount-Zero Taravale Wildlife Sanctuary, approximately 94 km WNW of Townsville, 11 Apr. 2018, J.E. Kemp & R. Jensen JEK20074 (BRI).
Fig. 2. Hibbertia advena. A flower; B young fruit. Photos: R. Jensen.
iagnostic features. Hibbertia advena can be distinguished from all other members of the genus by the combination of ± glabrous, linear, straight, pungent leaves with strongly revolute margins that obscure the abaxial lamina and are typically level with (but may be slightly lower or higher) than the midrib, pedicellate flowers with few to several bracts at the base of the pedicel that are linear-triangular to triangular and pungent, glabrous sepals, and usually 15 connivent stamens in 5 distinct groups of 3 stamens each, inserted between the 5 glabrous, usually 2-ovulate carpels.
Phenology. Flowers December to March and in fruit from January to May.
Distribution and habitat. Hibbertia advena is known from several locations in the Mount Zero-Taravale Sanctuary (owned and managed by the Australian Wildlife Conservancy), and from one location in the Ben Lomond Mining lease, west of Townsville, Queensland. These locations are in the Kennedy North botanical district and Broken River subregion of the Einasleigh Uplands IBRA (Interim Biogeographic Regionalisation for Australia) region (Department of Agriculture, Water and the Environment, 2022). It has been recorded growing on sand over granitic rocks in woodlands along creeklines with Melaleuca fluviatilis, Eucalyptus camaldulensis and Lophostemon grandiflorus.
Conservation status. Hibbertia advena is not currently conservation-listed. The size and extent of the known populations have not been recorded. One location is on a mining lease. We recommend that its conservation status be assessed.
Etymology. The epithet is from the Latin advena (outsider, foreigner, stranger), in reference to the species being morphologically unlike any other species of Hibbertia in eastern Australia, and being clearly related to but widely disjunct from species in southwest Western Australia. It is used here as a noun in apposition.
Proposed vernacular name. Taravale guinea-flower.
Notes. Hibbertia advena is morphologically very different from any other eastern or northern Australian Hibbertia species, and is most similar to species from Western Australia in the informally named H. exasperata species group, which also includes H. pungens Benth. and H. rostellata Turcz. All members of this group have ericoid, pungent leaves, pedicellate flowers with bracts at the base of the pedicels, and typically 15 stamens arranged around five, 2-ovulate glabrous carpels.
Given its wide disjunction, H. advena is unlikely to be closely allied to any of the Western Australian species in the H. exasperata species group. It shares straight leaf apices and few small, narrow, pungent bracts with H. pungens, but that species has prominently bulging abaxial leaf midribs and margins that are recurved (that is, the true leaf margins tightly abut the midribs with no grooves on either side, as occurs with species with revolute margins). Other species in Western Australia either have very short leaves, large, scarious, obtuse bracts, or uncinate leaf apices.
In eastern Australia, members of the H. pedunculata R.Br. ex DC. subgroup of the H. vestita Benth. species group (Toelken, 2013) also have ericoid leaves with an excurrent midrib, pedicellate flowers, and stamens arranged around the carpels. However, species in that group have leaves that are not pungent, stamens arranged in a ring around the carpels (rarely in two groups on opposite sides), and typically two or three densely pubescent carpels.
The strongly pungent leaves of H. advena are similar to H. ferox Jackes, which can be distinguished from the new species by having 9 (10) stamens around 2 glabrous carpels (cf. 15 stamens in 5 groups alternating with 5 glabrous carpels), sessile (cf. pedicellate) flowers, and scarious broadly lanceolate bracts that are 1.8–2 mm wide (cf. pungent narrowly linear-triangular bracts that are 0.2–0.5 mm wide). Hibbertia ferox also occurs much further inland (e.g. around White Mountains National Park) than does H. advena. Hibbertia advena can be distinguished from all other pungent-leaved species of Hibbertia in eastern Australia by having stamens arranged around the glabrous carpels (cf. stamens to one side of the usually hairy carpels).