Levenhookia aestiva Wege, 2020

Wege, Juliet A., 2020, Styleworts under the microscope: a taxonomic account of Levenhookia (Stylidiaceae), PhytoKeys 151, pp. 1-47 : 1

9. Levenhookia aestiva Wege sp. nov. Figs 2B , 5F , 6.

Levenhookia sp. Whicher Range (J.A. Wege 2090), Western Australian Herbarium, in FloraBase, https://florabase.dpaw.wa.gov.au/ [accessed 6 March 2020].

Diagnosis.

Levenhookia aestiva can be identified by its long (5.5-8 mm) corolla tube, long (7.5-11 mm) column, entire column sheath with 3 pendulous appendages, and long labellum (4.5-6.5 mm) with a prominent apical appendage and oblong-subulate basal appendages.

Type.

Australia. Western Australia: 1.1 km E on Sabina East Road from Sues Road, Whicher National Park, 18 Dec 2018, J.A. Wege 2090 (holo: PERTH 09082654; iso: AD, CANB, K, MEL, NSW).

Description.

Annual herb 4-15 cm high. Glandular hairs somewhat viscid, 0.2-0.6 mm long. Stem dark red or brownish red, simple or branched to varying degrees with porrect or ascending lateral branches, glandular-hairy. Leaves cauline, scattered, green or red, glandular-hairy on the margins and abaxially, with a few hairs adaxially (mostly towards the base); lamina narrowly oblanceolate to oblanceolate, elliptic or ovate, 3-25 mm long including the petiole, 1-5.5 mm wide, acute to subacute with a blunt tip. Flowers in racemes (inflorescence corymbose in few-flowered individuals), 1-ca. 300-flowered; bracts narrowly oblanceolate to oblanceolate, narrowly lanceolate or ± linear, 2-22 mm long, glandular-hairy like the leaves; pedicels 1-6 mm long, glandular-hairy. Hypanthium globose, obovoid or depressed-obovoid, 0.7-1 mm long, 0.8-1.5 mm wide, glandular-hairy. Calyx lobes subequal (with the anterior pair scarcely longer than the rest and rarely connate basally), 2.5-4.2 mm long, acute, glandular-hairy. Corolla pink, often with a dark pink midvein and with white or pale pink margins near the base of the lobes; lobes evenly arranged tending vertically-paired, elliptic or obovate with a slender claw, usually slightly recurved, sparsely glandular-hairy abaxially towards the base and along the midvein; anterior (lower) lobes slightly narrower than the posterior pair, 4.5-6.5 mm long, 2.2-3.2 mm wide, bluntly pointed or rounded; posterior (upper) lobes 4.5-6 mm long, 2.8-3.5 mm wide, bluntly pointed; tube whitish with pink longitudinal stripes distally, 5.5-8 mm long, exserted 1.5-4.5 mm beyond the calyx, sparsely glandular-hairy distally. Labellum ventral, 4.5-6.5 mm long including a 1.5-2.5 mm long claw; hood pink with dark red-purple markings adaxially, minutely papillate, sometimes with a few glandular hairs abaxially; basal appendages creamy white, pale yellow near the base, oblong-subulate, 1-2.5 mm long, acute or obtuse, sometimes papillate; appendage at the cleft apex pink, elliptic to obovate, 1.5-2 mm long, 0.8-1.4 mm wide, usually with an irregularly incised apex (rarely obtuse), glabrous. Column sheath deep pink, glabrous, 0.5-1 mm high, with an entire, thickened rim bearing 3 pendulous appendages on the inside. Column white basally, pinkish distally, free, forward-arched when enclosed by the labellum, slender but slightly thickened distally, 7.5-11 mm long, glabrous; stigmatic lobes to 1.3 mm long, incurved, apparently maturing subsequent to pollen release. Capsule depressed obovoid, 1.5-3 mm long excluding calyx lobes. Seeds 0.4-0.5 mm long, 0.2-0.3 mm wide.

Phenology.

Mostly flowering from mid-November to early February, with flowering extending into March and April in swampy habitats on the south coast; mostly fruiting from mid-December to February.

Distribution.

Most records of L. aestiva are from the south-west corner of Western Australia (Fig. 5E ) between Bunbury, Pemberton, Augusta and Yallingup in the Warren, Jarrah Forest and Swan Coastal Plain bioregions. There is an outlying, but morphologically comparable record near Denmark.

Habitat.

Levenhookia aestiva grows in sandy soils near swamps and on low lying flats, or in sandy loam with lateritic gravel in more upland habitats. It is commonly recorded from post-fire habitats and disturbed roadsides or firebreaks. Associated vegetation includes open Eucalyptus marginata , Corymbia calophylla or C. haematoxylon woodland with Kingia australis and Xanthorrhoea preissii , and low Myrtaceous shrubland. In lateritic habitats, it may grow in sympatry with Stylidium lateriticola Kenneally, a species with similarly bright pink, summer-blooming flowers.

Conservation status.

Despite its reasonably narrow geographic range, L. aestiva is locally common at numerous sites within the conservation estate (especially following a disturbance) and is not currently considered to be at risk ( IUCN (2012): Least Concern).

Etymology.

From the Latin aestivus (of summer), in reference to its flowering time.

Vernacular name.

Summer Stylewort.

Notes.

Specimens of L. aestiva have previously been placed under a broadly defined L. preissii ( Sonder 1845, Mildbraed 1908, Erickson 1958, Wheeler 2002, Lowrie and Conran 2011); however, there are several features that support its recognition as a distinct species. Corolla tube length (5.5-8 mm cf. 2-4.5 mm in L. preissii ) and column length (7.5-11 mm cf. 4.5-7.2 mm in L. preissii ) are taxonomically informative and readily observed on pressed material. Levenhookia aestiva also has a longer labellum (4.5-6.5 mm cf. 3-4 mm) with a larger apical appendage (1.5-2 mm × 0.8-1.4 mm cf. 0.7-1.5 × 0.4-0.6 mm) and longer basal appendages (1-2.5 mm cf. 0.4-0.7 mm long). Its corolla lobes lack the speckled markings that appear characteristic of L. preissii (compare Fig. 5D, F ) and its nectar sheath is morphologically distinct. Capsule shape may also be taxonomically informative (depressed obovoid in L. aestiva cf. ovoid in L. preissii ), although few mature capsules of the latter species have been viewed. The two species are not known to overlap in distribution (refer to the notes under L. preissii ).

Selected specimens examined.

Australia. Western Australia: 6.7 km N on Black Point Rd from Wapet Track, 30 Jan 1997, E. Bennett & B. Evans P 13.1 (PERTH); Creek View Rd, Reserve 12492, Quindalup, 10 Dec 2003, D. Carter 661 (PERTH); 32 km from Pemberton along road to Nannup, 21 Jan 1979, M.D. Crisp 5350 (CANB, PERTH); 15 km E of Karridale, 15 Jan 1996, R. Davis RD 443 (PERTH); Margaret River crossing on Rapid Rd, Whicher Range, 16 Jan 1986, A.H. Burbidge 3966 (PERTH); Denmark Shire, Nutcracker Rd, 1 km E from junction with Stan Rd, 2 Jan 1999, B.G. Hammersley 2150 (PERTH); 1 km along Rapids Rd from Canebreak Rd, Whicher Range, ca. 20 km S of Busselton, 13 Jan 1986, G.J. Keighery 8046 (CANB, PERTH); Forest Grove Block, 10 km S of Margaret River, 10 Dec 1990, G.J. Keighery 13750 (PERTH); Capel Nature Reserve, 13 Dec 1994, G.J. Keighery 13260 (PERTH); Ambergate Regional Park, 13 km SSW of Busselton, 14 Nov 1994, G.J. Keighery 15146 (PERTH); Joshua Brook Rd, Boyanup Forest Block, 15 Jan 1997, G.J. Keighery 15067 (PERTH); 7.25 km SW along Sabina Rd from Vasse Hwy, S of Busselton, 29 Nov 1995, J.A. Wege 154 & P. French (PERTH); Sues Bridge camping area on the Blackwood River, 50-100 m W of Sues Rd, SE of Busselton, 29 Jan 2009, J.A. Wege 1590 (PERTH); 6.1 km S of Governor Broome Rd on Milyeannup Coast Rd, N of Scott River, E of Augusta, 30 Jan 2009, J.A. Wege 1592 (PERTH).

Figures

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 A L. stipitata (unvouchered, Augusta area, Western Australia) B L. aestiva (J. A. Wege 2090) C-E L. 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 F L. aestiva (J. A. Wege 2090), labellum triggered with column momentum stopped by the sheath at the base of the corolla lobes G, H L. pauciflora (at J. A. Wege 1071 & C. Wilkins): note the unusual, distally-angled column and brush-tipped labellum I L. murfetii (J. A. Wege 2060): note the dorsal position of the labellum; J, K L. 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 5. Comparative distributions and floral morphologies A, B Levenhookia pauciflora, a Western Australian endemic with a brush-tipped labellum and distinctive corolla shape (J. A. Wege 1071 & C. Wilkins) C, D L. 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, F L. 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).