Geleznowia occulta K.A.Sheph. & A.D.Crawford, 2023

Anderson, Benjamin M., Binks, Rachel M., Byrne, Margaret, Crawford, Andrew D. & Shepherd, Kelly A., 2023, Using RADseq to resolve species boundaries in a morphologically complex group of yellow-flowered shrubs (Geleznowia, Rutaceae), Australian Systematic Botany 36 (4), pp. 277-311 : 302-304

Geleznowia occulta K.A.Sheph. & A.D.Crawford , sp. nov.

Type: Western Australia, south-west of Coorow [precise locality withheld for conservation reasons], 23 Aug. 2020, K. A. Shepherd & C. F. Wilkins KS 1743 (holo: PERTH 09507787 ; iso: AD, CANB, K, MEL, NSW) .

Erect, single-stemmed subshrub up to 0.2–0.4 m high; older branches light brown to light grey–brown and glabrous, younger branches yellowish-green with an indumentum of scattered to moderately dense, simple hairs up to 0.05–0.1 mm long. Leaves glaucous green or pale green, elliptic, 2.7– 5.3 mm long, 1.1–2.8 mm wide, adaxial surface slightly concave and glabrous or rarely with scattered hairs up to 0.05 mm long, abaxial surface glandular–verrucose, glabrous or with scattered hairs to 0.05 mm long. Flowers 1–3(5), yellow, terminal inflorescences 5.2–10 mm long. Pedicel of central flower 1.9–2.7 mm long, with dense hairs 0.1– 0.3 mm long. Bracts 0–3(4), yellow, sometimes tinged red post-pollination, elliptic, 3.7–6.3 mm long, 1.8–2.9 mm wide; adaxial surface glabrous or with scattered hairs up to 0.05 mm long; abaxial surface glandular–verrucose, glabrous or with scattered hairs 0.05 mm long. Bracteoles 0–2(4) usually paired below each flower except central flower, narrowly obovate, 5.2–7.2 mm long, 2–2.6 mm wide, both surfaces glabrous or with scattered hairs up to 0.05 mm long. Sepals yellow, oblong to elliptic, longer than petals, 6.3–6.9(7.3) mm long, 2.5–3.1 mm wide, glabrous or with scattered hairs up to 0.05 mm long. Petals yellow, cupped, coriaceous, narrowly elliptic, 4.2–5.9 mm long, 1.7–2.8 mm wide, glabrous. Stamens 10; filaments 1.2–3.2 mm long, broadening at base up to 0.3–0.5 mm wide, glabrous; anthers oblong, 1.1–1.6 mm long, 0.5–0.8 mm wide. Carpels 5, free, with two ovules per carpel, 1.5–1.6 mm long, 1.6–2.4 mm wide, verrucose, glabrous or with scattered hairs up to 0.05 mm long. Style glabrous, 1.7–3.5 mm long, 0.2–0.3 mm wide; stigma obovoid, 0.2–0.4 mm long, 0.5 mm wide. Fruit obovoid, 5.5–7 mm long, 5.2–8.5 mm wide. Seeds dark brown to black, 3.3–4.7 mm long, 2.2–3.1 mm wide; aril pale cream 2.0– 2.8 mm long ( Fig. 13 ).

Distribution and habitat

This species is currently known from only two populations west of Coorow and east of Goomalling ( Fig. 8 ) in the Geraldton Sandplains and Avon Wheatbelt bioregions (Department of Agriculture, Water and the Environment 2020). Found growing in deep yellow sand, sometimes in disturbed areas such as firebreaks, in low Banksia woodlands associated with Xylomelum , Grevillea and myrtaceous shrubs.

Phenology

Flowering in September and October with fruiting specimens observed in November and December.

Conservation status

This species is currently known from only two populations, one of which is on private property. The second population, although occurring in a nature reserve, has been observed only in low numbers. It is to be listed as Priority Two under Conservation Codes for Western Australian Flora ( T. Llorens, pers. comm.).

Etymology

From the Latin occultus (hidden, concealed) in reference to the cryptic nature of this species, because it was initially recognised as distinct through this molecular study, and that it is currently known from only two localities.

Notes

Geleznowia occulta can be distinguished from related Geleznowia by the following characters: a small subshrub 0.15–0.2 m high with glaucous green or pale green leaves; 1–3(5) flowers per inflorescence, surrounded by 0–3(4) yellow bracts, 3.7–6.3 mm long, 1.8–2.9 mm wide, abaxial surface glabrous or with scattered hairs 0.05 mm long; 0–2(4) bracteoles; sepals 6.3–6.9(7.3) mm long, 2.5–3.1 mm wide; and a broad stigma 0.5 mm wide. This species is very morphologically similar to the more widespread G. verrucosa , but can be recognised as distinct from it by its shorter inflorescences 5.2–10 mm long (cf. 12–15 mm long) usually with few flowers 1–3(5) per inflorescence (cf. 1–6 flowers per inflorescence), fewer bracts (0–3(4) cf. (4)5–7) that are narrower (1.8–2.9 mm wide cf. 2.4–5.5 mm wide) and fewer bracteoles (0–2(4) cf. 0–8).

Selected specimens examined

WESTERN AUSTRALIA. [localities withheld for conservation reasons] 8 Jan. 1999, L . Broadhurst 14 ( PERTH 05547822 ); 27 Nov. 1990, S. Patrick 505 ( PERTH 01165348 ); 4 Dec. 2000, J. Schmidberger JS 038 ( PERTH 05814855 ); 2 Sep. 2021, K. A. Shepherd & B. M . Anderson KS 1853 ( PERTH 9507760 ); 25 Sep. 2009, K. A. Shepherd & J. A . Wege KS 1314 ( PERTH 08152136 ); 23 Aug. 2020, K. A. Shepherd & C. F . Wilkins KS 1744 ( BM, BRI, CANB, HO, MEL, NSW, PERTH 09507779 ) .

Figures

Fig. 13. Geleznowia occulta: (a) habitat; (b) habit; (c) flowering stems with young buds showing solitary flowers with few bracts; (d) single flower showing petals as long as sepals and obovoid stigma; (e) old fruit. Vouchers: K.A. Shepherd & C.F. Wilkins KS 1744 (a, d); K.A. Shepherd & B.M. Anderson KS 1853 (b); K.A. Shepherd & C.F. Wilkins KS 1743(PERTH) (c, e). Photos: K. A. Shepherd.

Fig. 8. Distributions of all seven Geleznowia species in Western Australia. The base map is sourced from GADM (ver. 3.6, see https://gadm.org), with grey borders showing IBRA regions and subregions (Department of Agriculture, Water and the Environment 2020).