Australian Journal of
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Hibbertia erioclada K.R.Thiele, sp. nov.
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Type: Western Australia: Intersection of Kulin-Holt Rock Road and Lily McCarthy Road, 17 Sept. 2021, K.R. Thiele 5757 (holo: PERTH 9369279; iso: AD, CANB).

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Figure 2. Hibberia erioclada, K.R.Thiele 5757.

Spreading to straggling shrubs to 0.4 m high, multi-stemmed at base and probably resprouting after fire; young branchlets comprising densely packed, thickened, densely white-pubescent, persistent leaf bases (hypopetioles). Leaves mostly crowded at the apices of short-shoots, erect at first then spreading, oblong, 5–8 mm long, 1.5–2 mm wide, the margins strongly recurved to the thickened, prominent midrib, obscuring the abaxial lamina; hypopetiole thickened, dark brown, densely pubescent (tardily glabrescent), forming a thickened peg on the stem surface when the leaf is mature; epipetiole very short, densely woolly-pubescent; adaxial lamina not tuberculate, sparsely hairy (tardily glabrescent); abaxial lamina (visible only by dissection) densely pubescent; abaxial midrib broad, level with or bulging above the margins, glabrous, often with a narrow central, yellowish sclerenchymatous stripe bordered on either side by green mesophyll; apex obtuse and pungently apiculate. Flowers sessile, terminal on short-shoots, closely subtended by crowded leaves; flower-subtending bracts 6–11, reddish brown, scarious, narrowly triangular, the primary bract 2.5–3.5 mm long. Sepals ovate, 5.5–6.5 mm long, moderately to densely appressed-pubescent; midribs prominent; outer sepals shortly acuminate; inner sepals similar to the outer but less acuminate and broader. Petals 5, yellow, obovate, 7–10 mm long, deeply emarginate. Stamens 10, all on one side of the gynoecium and curving over it like a hand of bananas; filaments c. 0.5 mm long; anthers rectangular, 1.8–2.2 mm long, dehiscing by introrse, longitudinal slits. Staminodes absent. Carpels 2; ovaries compressed-globular, densely pubescent; styles curving excentrically from the carpel apex, 2–2.2 mm long. Ovules 4 per carpel. Fruiting carpels and seeds not seen.

Other specimens examined. WESTERN AUSTRALIA: (All PERTH): Kulin - Holt Rock (6232914, 6232922).

For full specimen details, see the following batch search of the ALA for the above set of specimens: https://biocache.ala.org.au/occurrences/search?q=qid:1687433977986&qualityProfile=ALA&disableQualityFilter=scientific-name#tab_mapView

Figure 2. Hibberia erioclada, K.R.Thiele 5757.

Diagnostic features. May be discriminated from all other species of Hibbertia in Western Australia that have pungent, non-tuberculate, ericoid leaves by the combination of sessile flowers with broad, shortly acuminate, silky sepals, ten stamens, and four ovules per carpel.

Phenology. Flowering specimens have been collected in September.

Distribution and habitat. Occurs in south-western Western Australia, where known from a few scattered localities between Kulin and Holt Rock. Occurs on plains on grey sandy-clay soils over laterite, in tall proteaceous-myrtaceous shrub-heath dominated by species of Allocasuarina, Hakea, Banksia, Melaleuca, Leptospermum, Isopogon, Petrophile and Callitris.

Conservation status. Hibbertia erioclada is known from only a few localities in a restricted area, none of which is in a conservation reserve. Its conservation status should be assessed.

Etymology. From the Greek erion (wool) and klados (a branch, twig or stem), in reference to the white-woolly young stems (with rather tightly packed, woolly, peg-like persistent hypopetioles).

Notes. Hibbertia erioclada and H. arenicola are superficially similar; see notes to H. arenicola for key differences. Hibbertia axillibarba is also superficially similar, but the leaf midribs in that species are rather weak and the leaf margins are recurved to each other (at least when dried) so that the midrib is hidden (while in H. erioclada the leaf margins are recurved to and closely abut the broad, prominent midrib).