Styleworts under the microscope: a taxonomic account of Levenhookia (Stylidiaceae)

Abstract

A taxonomic revision of the Australian endemic genus Levenhookia R.Br. (Stylidiaceae) recognises 12 species, of which L. aestiva Wege, sp. nov. from south-western Australia is newly described. Levenhookia preissii (Sond.) F.Muell. is lectotypified and recircumscribed as a Swan Coastal Plain endemic, resulting in its addition to the Threatened and Priority Flora List for Western Australia. Lectotypes are also selected for L. dubia Sond., L. leptantha Benth., L. sonderi (F.Muell.) F.Muell. and L. stipitata (Benth.) F.Muell. ex Benth. Verification of herbarium records has expanded the known distribution of L. murfetii Lowrie & Conran and L. pulcherrima Carlquist and has confirmed the widespread distribution of L. dubia across southern Australia including Tasmania, where it is currently listed as extinct-surveys based on information gleaned from historical collections may lead to its rediscovery in this State. Descriptions, distribution maps and photographs for all species are provided along with a key to species.

Keywords: Annual herbs; Flora of Australia; conservation; herbarium collections; taxonomy.

Figure 1.

Levenhookia is a genus of annual herbs endemic to Australia A distribution in temperate and semi-arid regions of Australia, scale bar 1000 km BL. leptantha (J.A. Wege 2063) CL. pusilla (J.A. Wege 1749 & W.S. Armbruster) DL. octomaculata (J.A. Wege 2074) EL. pulcherrima (J.A. Wege 1937). Photos by J.A. Wege.

Figure 2.

Labellum and column movement in Levenhookia. Black arrow = labellum hooded over column; white arrow = labellum ‘triggered’ to release column; yellow arrow = labellum repositioned following column release; blue arrow = column position immediately following release from labellum AL. stipitata (unvouchered, Augusta area, Western Australia) BL. aestiva (J.A. Wege 2090) C–EL. leptantha (J.A. Wege 2063), with labellum enclosing the column (C), triggered to release the column which moves to the opposite side of the flower (D) and subsequently repositioned (E) with the stigmatic lobes developed FL. aestiva (J.A. Wege 2090), labellum triggered with column momentum stopped by the sheath at the base of the corolla lobes G, HL. pauciflora (at J.A. Wege 1071 & C. Wilkins): note the unusual, distally-angled column and brush-tipped labellum IL. murfetii (J.A. Wege 2060): note the dorsal position of the labellum; J, KL. dubia, with the labellum opening (but not otherwise moving) to release the column (K). Photos by R.W. Davis (A, B) and J.A. Wege (C–K).

Figure 3.

Comparative distributions and floral morphologies A, BLevenhookia pusilla, with a disjunct distribution in Western Australia and South Australia and a dense inflorescence of pint-sized flowers (unvouchered, Mt Clarence, Albany, Western Australia) C, DL. murfetii, a Western Australian endemic with discrete markings at the base of the corolla lobes (J.A. Wege 1829) E, FL. sonderi, a rarity from South Australia and Victoria with red-purple markings on the labellum that are especially prominent in pressed material (unvouchered, from near St Andrews, Victoria). Photos by J.A. Wege (B), K.R. Thiele (D) and C. Lindorff (F). Scale bar on maps 1000 km.

Figure 4.

Comparative distributions and floral morphologies A, BLevenhookia dubia, with a widespread distribution across southern Australia and flowers with acute calyx lobes and a simple, sessile labellum (K.R. Thiele 3360) C, DL. leptantha, a widespread Western Australian endemic with an exserted corolla tube and fleshy bracts (J.A. Wege 1828) E, FL. pulcherrima, a poorly-known Western Australian endemic with an exserted corolla tube and distinctive corolla lobe shape and markings (J.A. Wege 1937). Photos by K.R. Thiele (B, D) and J.A. Wege (F). Scale bar on maps 1000 km.

Figure 5.

Comparative distributions and floral morphologies A, BLevenhookia pauciflora, a Western Australian endemic with a brush-tipped labellum and distinctive corolla shape (J.A. Wege 1071 & C. Wilkins) C, DL. preissii, a poorly-known Western Australian endemic with distinctive corolla makings, rounded basal labellum appendages and a white, lopsided column sheath (unvouchered, from NW of Cooljarloo) E, FL. aestiva, a Western Australian endemic with oblong-subulate basal labellum appendages and a pink column sheath (J.A. Wege 2090). Photos by J.A. Wege (B), M. Matsuki (D) and R.W. Davis (F). Scale bar on maps 1000 km.

Figure 6.

Levenhookia aestiva (J.A. Wege 2090) A annual habit showing the ascending lateral branches; B inflorescence as viewed from above, showing flowers with a long corolla tube and column and a pink, entire column sheath. Photos by J.A. Wege (A) and R.W. Davis (B).

Figure 7.

Comparative distributions and floral morphologies A, BL. stipitata, with a disjunct distribution in Western Australia and South Australia and flowers on long pedicels and with a prominent column sheath (J.A. Wege 1874). Inset showing coloured markings at the base of the corolla lobes that have been recorded for many populations (J.A. Wege 1873) C, DL. octomaculata, a Western Australian endemic with prominent corolla markings and a densely papillate labellum (J.A. Wege 2074) E, FL. chippendalei, widespread in arid areas of Western Australia and the Northern Territory, with the incised apical labellum appendage visible in the lower right flower (N. Gibson 6559, S. van Leeuwen, M.A. Langley & K. Brown). Photos by J.A. Wege (B, D) and K. Brown (F). Scale bar on maps 1000 km.