Ozothamnus vespertinus R.W.Davis, Wege & Schmidt-Leb., 2018

Schmidt-Lebuhn, Alexander N., Puttock, Christopher F., Davis, Robert W. & Wege, Juliet, 2018, Two new species of Ozothamnus (Asteraceae: Gnaphalieae) from Australia, Phytotaxa 336 (2), pp. 190-196 : 193-194

Ozothamnus vespertinus R.W.Davis, Wege & Schmidt-Leb. , sp. nov. ( Figure 3 )

Ozothamnus sp. Northampton (J.Brooker & M.Weir 913) WA Herbarium, in FloraBase, https://florabase.dpaw.wa.gov.au/browse/ profile/29520 (accessed 7 July 2017)

Type:— AUSTRALIA. Western Australia: Northampton [precise locality withheld for conservation reasons], 14 December 2005, J. Brooker & M. Weir 913 (Holotype PERTH 07219075!).

Diagnosis:— Ozothamnus vespertinus is similar to O. retusus Sonder (1853) & F.Muell. and O. scaber Mueller (1853) in possessing ridges of green, decurrent leaf tissue on young stems, linear leaves ca. 5–20 mm long, and papery, white involucral bracts, but it differs in its non-emarginate leaf apex and lower number of flowers per capitulum at ca. 8–9 versus 8–26.

Description:— Shrub to 0.5 m tall. Stems with pronounced green ridges from decurrent leaf tissue, ridges bearing very short conical hairs, indumentum between ridges white-woolly and glandular. Leaves spreading to slightly reflexed, sessile or with an indistinct petiole to 2 mm long, linear, 5–20 mm long, 0.8–1.5 mm wide, apex with a reflexed mucro, base decurrent, margin entire and tightly revolute to near the mid-rib; adaxial surface slightly channelled, with very short conical hairs and glands, abaxial surface white-woolly and glandular. Capitulescence a corymbose panicle, 10–50 mm in diameter. Capitula simple, cylindrical, 4.5–6.0 mm long, 1.9–2.5 mm wide, sessile or on a peduncle to 2 mm long. Involucral bracts largely tough and papery, spirally arranged, not radiating. Inner involucral bracts opaque white with yellowish to light brown stereome, oblanceolate, 2.8–4.5 mm long, 0.9–1.5 mm wide, apex obtuse or rounded and generally split, the base acute, abaxial surface with glands and few woolly hairs. Receptacle bracts (paleae) absent. Flowers 8–9 per capitulum, white to cream. Pappus of barbellate bristles or hairs 2.1–3.3 mm long, white to translucent, the tips somewhat inflated. Immature cypsela 0.9–1.1 mm long, surface with minuscule ‘twin’ hairs.

Etymology:— The epithet, which is Latin for evening or western, refers to the distribution of this species on the west coast of Australia.

Habitat:— Low Melaleuca shrubland or heath on a breakaway of exposed Kockatea Shale, on brown to red or grey loam.

Phenology:— The species has been collected in flower in late November and December.

Conservation status:— The single known population of this species is described as consisting of only six to twenty individuals. It is currently listed as Priority One (equivalent to IUCN (2012): Data Deficient) under Conservation Codes for Western Australian Flora ( Smith 2017), as O. sp. Northampton. If no additional populations are found it would fulfil at least criteria B2a and D of the IUCN category Critically Endangered ( IUCN 2012).

Known distribution:— Endemic to Australia. Known only from a single locality near Northampton, in the Geraldton Sandplains bioregion of Western Australia ( Figure 2 ). It is geographically isolated from all potentially related species.

Notes:— Ozothamnus vespertinus is part of a group of species occurring in semi-arid environments and characterised by green ridges on the stems produced by decurrent leaf tissue. It includes O. blackallii ( Burbidge (1958)) Anderberg (1991), O. lepidophyllus Steetz in Lehmann (1845), and O. occidentalis ( Burbidge (1958)) Anderberg (1991) from Western Australia, O. scaber from South Australia, O. decurrens Mueller (1859) and O. retusus from South Australia and Victoria, and O. adnatus de Candolle (1838) and O. tesselatus ( Maiden & Baker (1896)) Anderberg (1991) from south-eastern Australia. Of these, only geographically distant O. retusus , O. scaber and O. tesselatus have leaves of the same size and linear shape as O. vespertinus , but the first two differ in their generally bilobate-emarginate leaf apices and larger number of flowers per capitulum (8–26 versus 8–9 in O. vespertinus ), while the latter also differs in its membraneous and straw-coloured as opposed to papery and white involucral bracts.

Ozothamnus vespertinus was first collected by Jenna Brooker and Margi Weir during voluntary flora conservation work for Greening Australia in the Hutt River Catchment area. This region is geologically unique on account of exposed areas of organic-rich Kockatea Shale, which occurs as a subsurface layer elsewhere in the northern Perth Basin ( Playford et al. 1976). It is also botanically noteworthy, with several additional geographically restricted species known including Melaleuca huttensis Craven (1999) , Leucopogon sp. Port Gregory (C. Page 33) and Teucrium sp. Hutt River (W.H. Butler 54).

Additional specimens examined:— AUSTRALIA. Western Australia: Northampton [precise locality withheld for conservation reasons], 29 November 2011, A. Crawford 1620 ( PERTH 08576173 !) ; 31 July 2006, C. Page 42 ( PERTH 07400047 !) ; 1 December 2006, G. Phelan 1 ( PERTH 07449216 !) ; 23 November 2006, M. Weir 104 ( PERTH 07449224 !) .

Figures

FIGURE 2. Known occurrences of Ozothamnus filifolius (black triangles) and O. vespertinus (black circle). For comparison, the map also shows occurrences of the other species of Ozothamnus covered by the identification key in this paper as sourced from the Atlas of Living Australia (ala.org.au, accessed 4 December 2016): O. blackallii (white triangles), O. cassiope (grey squares), O. kempei (crosses), O. lepidophyllus (grey circles), and O. occidentalis (white squares).

FIGURE 3. Ozothamnus vespertinus,A. flowering heads, B. involucral bract, C. young stem surface with green ridges from decurrent leaf tissue, D. bark, E. adaxial leaf side, F. abaxial leaf side (A. Crawford 1620, PERTH).