Pultenaea praecipua subsp. temperata M.A.M.Renner & R.L.Barrett, 2022

Renner, Matthew A. M., Barrett, Russell L., Clarke, Steve, Clugston, James A. R. & Wilson, Peter H. Weston Trevor C., 2022, Morphological and molecular evidence refute a broad circumscription for Pultenaea glabra (Fabaceae: Mirbelieae), with implications for taxonomy, biogeography, and conservation, Australian Systematic Botany 35 (3), pp. 225-277 : 268-271

6b. Pultenaea praecipua subsp. temperata M.A.M.Renner & R.L.Barrett , subsp. nov.

Pultenaea sp. Nullo Mountain ( M. A. M.Renner et al. 9034) NSW Herbarium, PlantNet [https://plantnet.rbgsyd.nsw.gov.au/ accessed 22 Feb. 2022] .

Type: New South Wales, Central Tablelands, Wollemi National Park, Nullo Mountain , west of 2515 Nullo Mountain Road , narrow ridges above Lees Creek , 24 Sep. 2018, M. A. M. Renner 9031, R. L . Barrett , J. M . Allen & H. G . Washington (holo: NSW 1052799 ) .

Diagnosis

Pultenaea praecipua subsp. temperata is distinguished from P. praecipua subsp. praecipua by having narrower linear leaves 0.6–1.2 (average 1.8) mm wide the adaxial surface of which is enclosed by the inrolled leaf, such that the glaucous colour imparted by the dense covering of columnar papillae is not visible on plants in the field.

Irregular, upright, woody shrub up to 0.8 m tall, stems yellow–green with short antrorse–erect hairs when young, brown when mature. Branching irregular. Stipules black– red, aging black; furcate, narrowest at sinus apex, lamina flared below and lobes curve laterally above; lobes eccentrically keeled, apex acuminate but not attenuate, disc margins irregularly dentate, teeth close set. Leaves dark green on under surface and glaucous above; linear, 6–21.2 (average 14.1) mm long by 0.6–1.2 (average 0.8) mm wide; strongly inrolled, the adaxial surface is enclosed and obscured, and bears tall pill-box papillae, these are not as tall as in P. praecipua ; subsp. praecipua ; leaf apex pungent, short, orange to orange–brown; leaves bearing a few scattered hairs, these are dense at the leaf base and on the petiole, abaxial surface bears triangular mamillae formed by bulging epidermal cells; ventral epidermis hyaline there are two enlarged cells beneath the medial vascular trace, separating it from the ventral epidermis; there are three vascular traces, the medial is largest, orange-pigmented cells occur in the outer extremity of the abaxial leaf. Inflorescence with no internode compression, flowers in axils of normal vegetative leaves, which occur throughout flower-bearing portion of stem, which continues vegetative growth after flower production; stipules associated with flowers are shorter than the vegetative stipules. Flowers shortly pedicellate, pedicel glabrous, with five or six orange–brown trichomes present in the leaf axil below each flower, long or short, not glandular at apex. Calyx lobes broad, short triangular (shorter for their width than subsp. praecipua ), apices apiculate, base of ventral calyx lobes auriculate; lobes and tube sparsely hairy, concentrated at top of the tube but also extending onto the ventral lobes, which are hairier than the dorsal lobes; margins of ventral calyx lobes hyaline. Bracteoles short, triangular, apex not reaching the vertex of the adjacent calyx lobe sinus; with a medial band of short antrorse hairs. Corolla not seen. Pods not seen ( Fig. 28 , 29 ).

Distribution and ecology

The only known population of P. praecipua subsp. temperata grows on a sandstone shelf with shallow pale grey sandy loam soil, surrounded by dry sclerophyll forest including Eucalyptus oreades , Acacia obtusifolia , A. terminalis , Allocasuarina sp. , Banksia cunninghamii , Callitris rhomboidea , C. endlicheri , Leptospermum sphaerocarpum and Persoonia linearis .

Recognition

Pultenaea praecipua subsp. temperata can be recognised by the combination of linear leaves 0.6–1.2 mm wide with a distinct apiculus, crowded, pillbox papillae on the adaxial surface, and triangular mamillae on the abaxial surface. The leaves of P. praecipua subsp. temperata are narrower than those of P. praecipua , up to 1.2 mm wide, whereas in P. praecipua subsp. praecipua the leaves are up to 2.1 mm wide. Pultenaea praecipua subsp. praecipua is also unusual in having five vascular traces in the leaf transverse section, P. praecipua subsp. temperata has three.

Notes

The recognition of two subspecies within a species known by two populations that differ by but few characters is justified by their allopatry, their genetic distinctiveness, and the consistent manifestation of those morphological differences in all individuals. We have examined all known extant individuals of both subspecies, and there are no morphologically intermediate individuals. Leaf width is of consistent expression within individuals, and within populations, and is therefore a consistent difference between the two subspecies., each having a different mean and modal leaf width. The degree of molecular difference between these two populations could be argued as being insufficient to support subspecific status, but then what are subspecies if they are not morphologically and genetically distinct allopatric populations of a species? The situation here with P. praecipua is straight forward in part because of the fact that each taxon is known by a single population, such that we have more or less complete knowledge of patterns of morphological and molecular variation. This contrasts with the situation in P. mutabilis , wherein we have a relatively limited population-level sampling, one that is sufficient, perhaps, to suggest that patterns of morphological and genetic variation are complex, and more sampling to fully understand these is required; hence, our different approaches to the treatment of intra-specific variation in these two species.

Conservation status

Pultenaea praecipua subsp. temperata warrants listing as Critically Endangered under the IUCN criteria. Pultenaea praecipua subsp. temperata is known from a single population that has experienced a decline in the number of mature individuals in recent years, as evidenced by the number of dead standing individuals observed during our site visit in 2018. The species is threatened by exotic herbivores including goats and deer, and by stochastic processes to which small populations are susceptible, particularly those that increase mortality rates and reduce recruitment, including severe drought, and intensified fire-regimes. The species may be susceptible to Phytophthora ; ~200 dead individuals were observed in 2018 beneath a more or less closed Eucalyptus canopy; however, whether mortality was caused by shading, senescence, or disease was not established.

Etymology

From the Latin temperata, tempered or modest, in reference to the narrower leaves that enclose the adaxial leaf surface, reducing the conspicuousness of the striking contrast between adaxial and abaxial leaf surfaces.

Specimens examined

NEW SOUTH WALES. Central Tablelands: Nullo Mountain , ridge E of NW escarpment, Lee Creek catchment, Oct. 2003, H. G. Washington, ( NSW 612468 ); H. G. Washington, 31 Aug. 2003, ( NSW 608966 ); 14 Nov. 2003, H. G. Washington, ( NSW 704525 ); Nullo Mountain , W of 2515 Nullo Mountain Road, narrow ridges above Lees Creek catchment, 24 Sep. 2018, M. A. M. Renner 9029, et al. ( NSW 1052790 ); 24 Sep. 2018, M. A. M. Renner 9030 et al. ( NSW 1052798 ); 24 Sep. 2018, M. A. M. Renner 9032, et al., ( NSW 1052800 ); 24 Sep. 2018, M. A. M. Renner 9033, et al., ( NSW 1052801 ); 24 Sep. 2018, M. A. M. Renner 9034 et al., ( NSW 1052802 ) .

Figures

Fig. 28. Pultenaea praecipua subsp. temperata (= P. sp. Nullo Mountain (M. A. M. Renner et al. 903) line drawing. (a) Flowering branch detail; (b) habit; (c) stipule; (d) bud; (e) leaf abaxial surface; (f) leaf, adaxial surface; (g) leaf cross-section and adaxial surface; (h) leaf cross-section and abaxial surface. Scale bar: 10 mm (a); 26.7 mm (b); 2.7 mm (c); 4 mm (d); 5 mm (e, f); 1.6 mm (g, h). All from NSW 1022438, all from dried material.

Fig. 29. Pultenaea praecipua subsp. temperata (=P. sp. Nullo Mountain (M. A. M. Renner et al. 903)) photos. (a) Habit, showing the glaucous adaxial leaf surfaces and irregular branching. (b–f) Flowering shoots, showing buds produced in association with normal vegetative leaves. All from plants growing in the vicinity of NSW 1052799.