Australian Journal of
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Hydrocotyle inops A.R.Bean sp. nov.
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Type: Queensland. Moreton district: 100 metres SW of Apple Tree Park, Springbrook, 30 January 2023, A.R. Bean 35184 (holo: BRI; iso: CANB, MEL, NSW).

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Figure 4. Hydrocotyle inops. a. leaf, upper surface b. leaf, lower surface c. fruits (all from Forster PIF46090 & Leiper).

Prostrate stoloniferous herb; stems filiform, sparsely to densely hairy. Stipules orbicular to ovate, 0.9–1.0 x 0.8–1.0 mm, white; margin dentate. Petioles of fully developed leaves terete, 3–42 mm long, inserted at base of lamina; petiole hairs very dense at distal end, becoming less dense proximally, 0.6–1.1 mm long, retrorse to spreading, white or brown. Lamina orbicular-cordate, radius 5–10 mm, with 5–8 major palmate veins; margin with 5–7 shallow lobes, each lobe crenate to crenulate, or without distinct lobes; radius at major sinuses 80–90% of lamina radius; upper surface moderately hairy, hairs ± appressed, 0.3–0.8 mm long, reddish punctate glands absent; lower surface moderately to densely hairy; hairs white, spreading, 0.3–0.8 mm long. Inflorescence umbellate, 4–8-flowered; all flowers bisexual; peduncles 5–17 mm long, longer than the adjacent petiole, with dense hairs 0.2–0.4 mm long. Involucral bracts 3–6, narrowly elliptic, 0.5–0.8 mm long; pedicels 0–0.2 mm long; petals white, c. 0.25 mm long, anthers c. 0.15 mm long. Schizocarps symmetrical, strongly compressed; mericarps 2, 1.0–1.3 mm long, 0.7–0.75 mm wide, brown, with abundant slender spreading hairs 0.1–0.2 mm long; dorsal ribs not winged; lateral ribs not prominent. Fruiting styles 0.2–0.4 mm long; style base swollen. Fig. 4.

Specimens examined: Queensland. Moreton district: c. 2 km SW of Hinze Dam eastern boat ramp, 2 Jul 2019, J.L. White 6 & D. Jinks (BRI); Gold Coast Hinterland great walk, adjacent to Apple Tree Park, 19 Dec 2018, P.I. Forster PIF45910 & G. Leiper (BRI); Gold Coast Hinterland great walk, adjacent to Apple Tree Park, 13 Mar 2019, P.I. Forster PIF46090 & G. Leiper (BRI).

Figure 4. Hydrocotyle inops. a. leaf, upper surface b. leaf, lower surface c. fruits (all from Forster PIF46090 & Leiper).

Distribution & habitat. Known only from near Springbrook and Hinze Dam in Queensland (Fig. 1). It grows in tall eucalyptus forest (E. microcorys F.Muell., E. campanulata R.T.Baker & H.G.Sm., E. saligna Sm.) with some rainforest species in the understorey, and a ground layer dominated by ferns.

Etymology. From the Latin inops, meaning ‘poor, weak, helpless’. This is in reference to the small size and prostrate habit of the species.

Notes. H. inops is distinctive by virtue of its small orbicular leaves with very shallow lobes, dense brown to white hairs on both surfaces of the lamina and on the petioles and stems, and by the abundant hairs 0.1–0.2 mm long on the fruit surface. Its closest relative is unknown; H. inops is somewhat similar in appearance to H. algida N.A.Wakef., but differs by the 3–8-flowered umbels (10–15-flowered for H. algida), the peduncles 5–17 mm long (10–70 mm for H.algida) and the hairy mericarps (glabrous for H. algida). H. algida measurements from Duretto (1999).