Diospyros hequetiae G.E. Schatz, Lowry & Fleurot, 2018

Schatz, George E. & Lowry Ii, Porter P., 2018, Novitates neocaledonicae. IX. Taxonomic notes on New Caledonian Diospyros (Ebenaceae) with new synonymy and the description of two new species, Candollea 73 (1), pp. 91-100 : 94-97

Diospyros hequetiae G.E. Schatz, Lowry & Fleurot , spec. nova ( Fig. 1 , 2 ).

Distinguished from other New Caledonian species of Diospyros by its small, coriaceous, flat, elliptic to orbicular leaves with the upper surface glabrous and shiny, and with obscure or barely visible venation, and the lower surface very sparsely covered with appressed black or white trichomes.

Holotypus: NEW CALEDONIA. Prov. Nord: Entrance to Presqu’île de Muéo , on road from Col de Muéo to Népoui , partially disturbed maquis above road, serpentinite, 21°17’52’’S 165°00’30’’E, 55 m, 6.XII.2016, y. fr., Lowry, Schatz & Fleurot 7460 ( P [ P 00580362]!; iso-: G [ G00341727 ]!, MO [ 3034508 ]!, NOU!, W!).

Shrub to small tree 2-3 m, stems densely covered with appressed, short (0.2-0.3 mm), whitish golden trichomes. Leaves elliptic to broadly elliptic, occasionally slightly obovate or orbicular, (0.8-)2-3.9 × (0.7-) 1.2-2.6 cm, coriaceous, base rounded to acute, margin micro-thickened to slightly microrevolute, drying darker than the blade, apex acute to rounded to rarely emarginate, midvein flat above, flat at the apex and progressively more raised towards the base below, venation weakly brochidodromous, secondary veins 4 or 5 per side, barely visible and flat to very slightly raised above, evident to barely evident to completely obscure below, tertiary veins reticulate, upper surface glabrous and shiny, lower surface very sparsely covered with appressed, black or white trichomes 0.1-0.2 mm long; petiole 2-3 mm, 1 mm in diam., densely covered with appressed, short (0.2-0.3 mm), golden trichomes, drying black. Male flowers in subsessile fascicles of 2 or 3 borne in the axils of leaves, 3-merous; peduncle and pedicel together 1-1.5 mm; flowers subtended by a narrowly ovate bract, to 2.5 × 1.5 mm, adaxially concave, moderately densely covered with semi-appressed light brown trichomes 0.5 mm long; calyx in bud narrowly ovoid to narrowly ellipsoid, the distal half cylindrical at anthesis, c. 4 mm tall, 2.5 mm in diam., lobes triangular, 1 × 1 mm, moderately densely covered with semi-appressed light brown trichomes 0.5 mm long; corolla exserted beyond calyx, cylindrical, 7 mm tall, 1 mm in diam., lobes triangular, 1 × 1 mm, densely covered with semi-appressed light brown trichomes 1.5 mm long, shorter and less dense towards the lobes, the margins of the lobes glabrous. Female flowers solitary and subsessile, borne in the axils of leaves, 3-merous; flower subtended by 2 or 3 elliptic bracts, 4 × 2.5 mm, adaxially concave, moderately covered with semi-appressed light brown trichomes 1 mm long; calyx urceolate, to 5.5 m tall, 4 mm in diam, the lobes triangular, 2 × 2 mm, densely covered with semiappressed light brown trichomes 1 mm long; corolla exserted beyond calyx, cylindrical, to 5.5 mm tall, the lobes narrowly triangular, 2.5 × 2 mm, densely covered with appressed light brown trichomes 1 mm long. Fruits ellipsoid to spherical, to 14 mm in diam., crowned by the style/stigma remnant to 1 mm long, moderately densely covered with appressed light brown trichomes 0.5 mm long; calyx in fruit accrescent, cupuliform, appressed to the fruit, 11 mm tall, to 20 mm in diam. overall, lobes broadly triangular, 6-7 × 8-15 mm, c. 1.5 mm thick at the base to <1 mm thick at the margins, apex of lobes rounded, not to slightly reflexed, margins becoming weakly revolute toward the apex, moderately densely covered with appressed light brown trichomes 0.5 mm long outside, more densely covered inside. Seeds spherical wedge-shaped, 8 × 3.5 mm, glabrous, surface wrinkled when dry, brown.

Etymology. – The species epithet honors our colleague Vanessa Hequet (Institut de Recherche pour le Développement, Nouméa), with whom we have had particularly informative discussions about New Caledonian Diospyros . She first encountered the new species at its type locality during her extensive field work in the context of the project on the conservation of the dry forests of western New Caledonia.

Distribution and ecology. – Diospyros hequetiae occurs in dry maquis on ultramafic (serpentinite) soils at three locations in northwestern Grande Terre, from 55 to 350 m elevation ( Fig. 3 ).

Conservation status. – Diospyros hequetiae has a geographic range in the form of an Extent of Occurrence (EOO) of 48 km 2 and a minimum Area of Occupancy (AOO) of 12 km 2, and exists at 3 locations with respect to the principal threats of fire and deer, both of which result in continuing decline in habitat quality. It therefore qualifies as «Endangered» [EN B1ab(iii)+2ab(iii)] using the IUCN Red List Categories and Criteria ( IUCN, 2012).

1 cm 5 mm 1 cm

Notes. – Diospyros hequetiae is distinctive among other dry forest species on ultramafic substrate by its small, flat, elliptic to orbicular leaves with white or black appressed trichomes on the lower surface, vs strongly revolute margins and glabrous lower surface of the leaves of D. revolutissima . Leaves in some material of D. minimifolia can resemble somewhat those of D. hequetiae in their size, shape and flatness, but the fruits of D. minimifolia are considerably smaller and, moreover, D. minimifolia occurs only on black clay soils.

Paratypi. – NEW CALEDONIA. Prov. Nord: Pic aux hirondelles , fr., 21°15’56’’S 164°57’48’’E, 64 m, 1.X.2017, y. fr., Fleurot 398 ( G, MO, NOU, P); 21°15’56’’S 164°57’49’’E, 68 m; ibid. loco, fr., Fleurot 399 ( NOU); ibid. loco, y. fr., Fleurot 400 ( MO, NOU, P); ibid. loco, 21°15’55’’S 164°57’50’’E, 76 m, y. fr., Fleurot 401 ( NOU, P); ibid. loco, 21°15’55’’S 164°57’50’’E, 77 m, fr., Fleurot 402 ( NOU, P); Pic aux hirondelles , 10 km au S de Pouembout, 6.III.2007, fr., Hequet 3659 ( NOU); entrée de Népoui , 20.XI.2007, fr., Hequet 3791 ( NOU); ibid. loco, ♂ fl., Hequet 3792 ( MO, NOU); entrance to Presqu’île de Muéo , on road from Col de Muéo to Népoui , 21°17’52’’S 165°00’30’’E, 55 m, 6.XII.2016, fr., Lowry, Schatz & Fleurot 7459 ( MO, NOU, P); pente SE du Mt. Koniambo , [21°00’32’’S 164°51’06’’E], 350 m, 23.VIII.1966, fr., MacKee 15499 ( K, NOU, P).

Figures

Fig. 1. - Diospyros hequetiae G.E. Schatz, Lowry & Fleurot. A. Fruiting branch; B. Lower leaf surface; C. Upper leaf surface; D. Fruit. [Lowry, Schatz & Fleurot 7460, P] [Drawings: R.L. Andriamiarisoa]

Fig. 2. - Diospyros hequetiae G.E. Schatz, Lowry & Fleurot. A. Upper leaf surfaces; B. Lower leaf surfaces, females flowers, and fruit; C. Fruit. [Lowry, Schatz & Fleurot 7460] [Photos: P.P. Lowry II]

Fig. 3. - Distribution of Diospyros hequetiae G.E. Schatz, Lowry & Fleurot (solid circles) and D. rufotomentosa G.E. Schatz & Lowry (open circles with dot).