Eucalyptus cryptica T.C.Wilson, S.Rutherf. & S.M.Douglas, sp. NOV.

Wilson, Trevor C., Rutherford, Susan, Yap, Jia-Yee S., Douglas, Steven M., Lee, Enhua & Rossetto, Maurizio, 2023, Eucalyptus cryptica (Myrtaceae): a critically endangered new species, Australian Systematic Botany 36 (5), pp. 386-400 : 390-399

Eucalyptus cryptica T.C.Wilson, S.Rutherf. & S.M.Douglas, sp. NOV.

Type: Australia: New South Wales: Central Coast: Sydney: Annangrove , 14 Oct. 2019, T.C.Wilson 830, S.Rutherford & J.Yap (holo: NSW 1058373 ! iso: BRI!, CANB!, MEL!) .

Eucalyptus sp. Cattai (Gregson s.n., 28 August 1954) NSW Herbarium: Royal Botanic Gardens and Domain Trust, PlantNET database record (see https://plantnet.rbgsyd.nsw.gov.au).

Diagnosis

Morphologically most similar to E. notabilis . Both species have strongly discolourous and narrowly to broadly ovate adult leaves with a glossy abaxial surface, buds with obtusely conical or hemispherical opercula bearing a scar, and a hemispherical or obconical fruit with a level to slightly raised disc. It differs from E. notabilis by its fibrous and somewhat eximious (i.e. with thin flakes on ridges) bark ( v. fibrous but not eximious) and by having fruit with valves reaching only slightly past the rim of the disc ( v. valves strongly exserted).

Description

Erect, multi-stemmed mallee or tree with a single but crooked stem, 5(–10) m tall, lignotuber present. Bark fissured, somewhat fibrous and eximious, greyish-brown on exposed areas, reddish-brown underneath. Juvenile Stem bright green to red; Adult Branchlets quadrangular, glabrous, pale or bright green to red. Cotyledon petiole (0.1–)1–1. 8(–3.9) mm long, (0.1–)0.3–0.55(–0.7) mm wide; cotyledon lamina surface matte, (0.9–)1.8–3.8(–9.5) mm long, (0.5–) 1.6–3.8(–5.2) mm wide, reniform, apex shallowly and broadly emarginate, base truncate to shortly attenuate. Juvenile leaves opposite for 2 or 3(8) nodes prior to transition to alternate phyllotaxy, petiole (usually present) (0.12–) 0.9–4.3(–21.6) mm long, (0.2–)0.3–1(–2) mm wide; lamina narrow ovate to ovate or nearly oblong, discolourous, bright to dark yellowish-green, margin entire, glabrous, (1–) 5–36(–60) mm long, (0.6–)2–12(–61) mm wide, 0.1–1 mm thick, apex acute, base equal or unequal sided and cuneate to shortly tapering. Adult Leaves petiolate, alternate, flat to partially pendulous, glabrous; petiole green to reddish- or yellowish-green, 5–17(–22) mm long, 1–2 mm wide; lamina discolourous, margin entire with recurved ridge, adaxial surface dark green and glossy, abaxial surface glaucous and dull, (32–) 40–170 mm long, 10–27(–40) mm wide, narrowovate to broad-ovate, elliptic or sometimes weakly falcate, apex acute, rarely obtuse or uncinate, base cuneate to attenuate and sometimes oblique, veins sparsely to moderately reticulate, secondary veins 45–90°, intramarginal vein visible, 0.5–3.2 mm from margin; oil glands mainly occurring between veins (island-type), up to 0.15 mm wide, 1–7(–10) glands mm −2. Inflorescence axillary, unbranched, held erect, 7-flowered (occasionally fewer by abortion); peduncles rounded to angular, 4–13(–33) mm long, 2–5 mm wide; pedicels thickened, flattened and angular, 0.3–4 mm long, 0.5–2.1 mm wide. Flower Buds glabrous, smooth, shallowly ribbed when dry, 6–15 mm long, outline ampulliform, obpyriform or obconical, outer operculum scar present, hypanthium:operculum length ratio 1–1.9; hypanthium 3.5–9.5 mm long, 3–6 mm wide, occasionally ribbed; operculum 2–7 mm long, 4–8 mm wide, apex compressed and acute to obtuse or sometimes beaked. Stamens white or yellowish-white at anthesis, all fertile; filaments irregularly inflexed in bud, 2.5–6.5 mm long, 0.1–0.2 mm wide; anthers 0.4–0.8 mm long, 0.3–0.6 mm wide, oblong, dorsifixed, versatile, dehiscing by parallel slits. Gynoecium: style 2.5–5 mm long, 0.5–0.7 mm wide, ovules 0.3–0.7 mm long, 0.2–0.3 mm wide. Fruit 4.9–9 mm long, 5–8 mm wide, hemispherical, cupular or obconical (excluding disc and valves), pedicel 0.7–2.6 mm long; disc 0.4–1 mm wide, level to slightly ascending; valves 3 or 4(5), free, erect, enclosed, often with apices exserted up to 2 mm past disc. Seeds yellowish-orange to orange–brown, cuboid or crescent- or wedge-shaped in outline, 0.7–1.7 mm long, 0.2–0.5 mm wide, hilum terminal. ( Fig. 5, 6 , 7 .)

Distribution

Approximately 700–800 individuals are restricted to 14 known sites in water catchments within or in close proximity of Cattai Creek of north-western Sydney, New South Wales, Australia, spanning the suburbs of Kellyville, Maraylya and Glenorie ( Threatened Species Scientific Committee 2018). Our searches for the species in seemingly identical habitat in adjoining water catchments and local government areas have not detected any individuals.

Habitat

Plateaux and gentle slopes with a western aspect, in shallow or poorly drained soils derived from upper Hawkesbury Group sandstone and overlying Mittagong Formation, sometimes also with laterite. Associated soil landscapes include Lucas Heights and Faulconbridge ( Bannerman et al. 2010; Bannerman and Hazelton 2011). The species occurs in heathland or low, open woodland mixed with a dense understorey of shrubs, sometimes associated with sandstone pavements or outcrops.

Phenology

Flowering has been recorded between October and January. Anecdotal observations suggest that insects are pollinators, although further study of reproductive biology is warranted.

Conservation status

The number of individuals is estimated between 700 and 800 individuals. No occurrences are known from formal conservation estate, some occur on unreserved Crown (State-owned) land, but most are present on freehold rural–residential and non-arable rural land and associated Council-managed roadsides. The species is listed as Critically Endangered in a conservation advice by the Threatened Species Scientific Committee (2018), which indicates that the area where E. cryptica occurs is highly fragmented as a result of urbanisation and is threatened further by an intensification of urban expansion. Genetic swamping from unidentified eucalypt species was also detected by Rutherford et al. (2022) and is a natural threat observed in rare and restricted eucalypts ( Larcombe et al. 2014; Rutherford et al. 2019).

Etymology

From the latinised Greek ‘ crypticus ’ (i.e. hidden), the epithet refers to the recent near obscurity of this species. Despite herbarium specimens being collected since 1967 and the populations being situated in the largest city in Australia, it has remained unclear to science whether it is a species or a collection of populations of hybrid origin.

Notes

In addition to Eucalyptus sp. Cattai (Gregson s.n. 28 Aug 1954), E. cryptica is also cited informally as ‘ Eucalyptus sp. Cattai (NSW218983)’ and ‘ E. notabilis – resinifera subsp. resinifera ’ in the Flora of NSW (PlantNET 2023).

Similarities and differences between E. cryptica and the species of E. subgenus Symphyomyrtus section Latoangulatae series Annulares ( Nicolle 2019) it closely resembles are summarised in Table 3. Eucalyptus cryptica is sympatric with the more widely distributed E. squamosa H.Deane & Maiden , a similar-looking mallee that is placed in E. subgenus Symphyomyrtus section Bisectae series Squamosae Chippend. It can be readily distinguished from E. squamosa by its longitudinally fissured bark ( v. scaly or tessellated), discolourous leaves ( v. concolourous ), single axillary inflorescence ( v. inflorescence paired), buds generally having a smooth surface ( v. often verrucose) and fruit with valves reaching only slightly past the rim of the disc ( v. valves distinctly exserted).

Specimens examined

AUSTRALIA: NEW SOUTH WALES (specific localities removed according to endangered listing): 20 Sep. 2018, K.E.Willis 31, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051607); 14 Oct. 2019, T.C.Wilson 829, S.Rutherford & J.Yap (NSW 1058372, NSW 1059242, NSW 1059243, NSW 1059244, NSW 1059246); 31 Oct. 1964, A.Rodd s.n. (NSW 318985); 20 Sep. 2018, K.E.Willis 25, G.Errington, J.Wait & E.Lee (NSW 1057506); 20 Sep. 2018, K.E.Willis 37, G.Errington, J.Wait & E.Lee (NSW 1051639); 20 Sep. 2018, K.E.Willis 38a, G.Errington, J.Wait & E.Lee (NSW 1051640); 20 Sep. 2018, K.E.Willis 38b, G.Errington, J.Wait & E.Lee (NSW 1051641); 20 Nov. 2018, T.C.Wilson & E.Lee s.n. (NSW 1050034); 14 Oct. 2019, T.C.Wilson 831, S.Rutherford & J.Yap (NSW 1058374, NSW 1059222); 21 Feb. 2019, E.Lee & N.Izquiedo s.n. (NSW 1029038); 13 May 2001, M.I.H.Brooker 13208 (NSW 923591); 13 May 2001, M.I.H.Brooker 13209 (NSW 923587); 13 May 2001, M.I.H.Brooker 13211 (NSW 923377); 20 Sep. 2018, K.E.Willis 32a, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051609); 20 Sep. 2018, K.E.Willis 32b, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051611); 20 Sep. 2018, K.E.Willis 33, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051613); 20 Sep. 2018, K.E.Willis 34, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051614); 20 Sep. 2018, K.E.Willis 35, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051615); 20 Sep. 2018, K.E.Willis 36, G.Errington, J.Wait, E.Lee & E.Roper (NSW 1051616); 5 July 2019, T.C.Wilson, S.Rutherford, G.Errington, E.Roper, Z.Aliberti & S.Hunt s.n. (NSW 1028368, NSW 1048012, NSW 1048007); 14 Feb. 2011, M.I.H.Brooker 13207 (NSW 923482); 20 Nov. 2018, T.C.Wilson, E.Lee & P.Barry s.n. (NSW 1050035); 23 Sep. 2010, Klaphake 1b & R.Haq (NSW 874083); 2 Nov. 2018, T.C.Wilson, S.Rutherford, G.Errington & E.Lee (NSW 1048003); 23 Sep. 2010, Klaphake 6b & R.Haq (NSW 874088, NSW 2299635); 5 Mar. 2019, T.C.Wilson & S.Rutherford s.n. (NSW 1042424); 28 Aug. 1954, E.J.Gregson s.n. (NSW 318983, NSW 2299633); 15 Sep. 2015, M.Stables s.n. (NSW 986406).

Figures

Fig. 6. Eucalyptus cryptica. (a) Habit of seedling grown from K.E.Willis 37 (NSW 1043128); (b) habit of seedling, grown from K.E.Willis 34 (NSW 1047892); (c) seedling with cotyledons, grown from K.E.Willis 34 (tissue sample unknown); (d) seedling with cotyledons, grown from K.E.Willis 34 (tissue sample unknown); (e) mallee habit of adult; (f) detail of bark. Scale bar: (a) 20 mm; (b) 20 mm; (c, d) 2 mm; (e) 1 m; (f) 100 mm. Illustrations: (L. Elkan).

Fig. 7. Images of Eucalyptus cryptica. (a, d) Type locality, without associated voucher; (b, e) T.C.Wilson 830; (c) T.C.Wilson 829. (a) Mallee tree habit in heath; (b) sample of bark, branchlet with unopened inflorescences and senesced branchlet with fruit; (c) inflorescence; (d) flowers at anthesis; (e) oblique view of infructescence showing undehisced fruit. Scale bar: (b) 30 mm; (c) 10 mm; (d, e) 5 mm. Photographs: E. Lee (a, d) and T. C. Wilson (b, c, e).