Marsdenia mackeeorum Meve, Gâteblé & Liede, 2017

Meve, Ulrich, Gâteblé, Gildas & Liede-Schumann, Sigrid, 2017, Taxonomic novelties in Apocynaceae subfam. Asclepiadoideae from New Caledonia, Adansonia 39 (1), pp. 55-70 : 60-62

Marsdenia mackeeorum Meve, Gâteblé & Liede , sp. nov.

( Fig. 4 )

A slender vine with linear to slenderly elliptic, discolorous leaves as in M. microstoma but with cymose (bostrychoid) inflorescences with persistent rachis elongating with age (vs sciadioidal inflorescences in M. microstoma ), ascending-erect connective appendages (vs inwardly bent in M. microstoma ), and a significantly conical style-head (vs depressed-conical style head in M. microstoma ).

TYPUS. — New Caledonia. Grande-Terre, South Prov., Yaté, Gouemba , 500 m, in maquis on serpentine soil, 22.III.1981, H.S.MacKee 38863 (holo-, P [ P00607333 ]! ; iso-, P [ P00607334 ]) .

PARATYPI. — New Caledonia. Grande-Terre: Road to Mt. Dzumac , N of Dumbéa , 8.I.2004, P.P.Lowry et al. 6332 ( NOU050203 ) ; La Coulée , 10 m, 13.VI.1971, H.S.MacKee 23841 (P04222323) ; Kouaoua/Canala, Dahi , 500 m, 30.III.1977, H.S.MacKee 32981 (P) ; Yaté, Haute rivière blanche, 450 m, 4.V.1981, H.S.MacKee 39024 ( NOU017827 ; P04222319) ; Yaté, 100 m, 22.XI.1985, H.S.Mackee 42925 ( NOU057812 ,P04593769) ; Plaine des lacs region, E of Grand Lac , along road to Haute Kuébini , 3 km along Kuébini rd, c. 300 m, 4.XI.1982, G.McPherson 5050 (MO, NOU017828 , P04222320) ; s.loc., 1861-1867, E.Vieillard (leg. Pancher) 3004 (P04222321) ; Mont Dore-Dumbéa, Montagne des Sources , 22.VIII.1968, G.L.Webster & R.Hildreth 14950 (P04222322) .

Possibly also: Yaté , 100 m, 17.V.1992, H.S.Mackee 45818 ( P04593759 ), sterile .

ETYMOLOGY. — Named after Hugh S. MacKee (1912-1995) and his wife Margaret E. MacKee (?1913-1990). Hugh S. MacKee was supposedly the biggest and best collector in New Caledonia ever. His wife was always helping him in collecting and preparing the samples ( Morat 1995, 2010).

DISTRIBUTION AND HABITAT. — New Caledonia. Grande-Terre, North and South Provinces ( Fig. 3 ). On serpentine, in moist forests or maquis, 10 - 700 m. Marsdenia mackeeorum , sp. nov. is typically found on ultramafic derived soils (serpentinite) in the southernmost part of Grande-Terre.

CONSERVATION STATUS. — Most of the locations are in the southernmost part of Grande-Terre south of Mt. Dzumac with one locality outside this range, between Canala and Kouaoua. All localities are on ultramafic substrate with some of them under mining concessions and some others not. Bush fires could also be a threat to the populations occurring in maquis vegetation. With more than five localities, an EOO of 1950 km ² and an AAO of 32 km ², we are assigning a preliminary IUCN conservation status of “Vulnerable” [VU B1ab(ii,iii,v)+2ab(ii,iii,v)] using Red List criteria ( IUCN, 2012).

DESCRIPTION

Plants

Ascending, twining to 3 m high.

Shoots

Perennial, herbaceous, glabrous.

Latex

White (fide MacKee 38863, 39024).

Leaves

With petiole 5-10 mm long, leaf blades coriaceous, with 3-5 colleters at the base, discolorous, 5-13 × 0.7-0.9 cm wide, linear to narrowly elliptic, basally rounded, apically acute, marginally revolute, glabrous on both sides.

Inflorescences

Always one per node, extra-axillary, bostrychoid, partial inflorescences geminiflorous, 12-25-flowered, 3-9 flowers open synchronously. Peduncles 5-7mm long, glabrous; rachis 8-12 mm long, persistent, straight.

Flowers

With floral bracts c. 0.7 mm long, c. 0.5 mm wide at the base, triangular, glabrous or apically ciliate. Pedicels 4-7 mm long, with a single line of appressed, c. 150 µm long trichomes. Flower buds 2.5-3 × 1.5-2 mm when mature, conical.

Calyx

Entirely free, glabrous; lobes 0.6-0.8 × 1-1.2 mm, ovate, apically obtuse.

Corolla

Urceolate, 3-4 mm long, c. 2.5 mm diam., whitish, yellow or rose, adaxially with 350-450 µm long trichomes, concentrated on the throat of the tube; lobes fused for about half of total corolla length, c. 1 mm wide, incurved, triangular, apically acute.

Gynostegial corona of free staminal lobes

Glabrous, 0.6-0.8 mm long, shorter than the gynostegium; lobes laminar, triangular.

Gynostegium

1.2-1.4 mm long, 1.4-1.5 mm diam., elevated by a column of 0.5-0.7 mm length; anthers about as long as broad, rectangular, abaxially planar; anther wings 400-500 µm long, divergent, extending along the whole length of the anther, consisting of distal ridge alone; anther wings of adjacent anthers parallel to each other, basally widened, in the same plane as the anther; connective appendages 450- 500 × 300-350 µm, triangular, narrower than the stamen, slightly inflexed.

Pollinarium

Corpusculum 380-400 × c. 100 µm, ovoid to elliptic, margins of the corpuscular cleft centrally widened; caudicles 80-100 µm long, (sub-)basally inserted at the corpusculum, cylindrical, straight, horizontal; pollinia apically attached to the caudicles, erect, c. 250 × 140-150 µm, round in cross-section, ovoid.

Style-head

0.7-0.8 mm long, c. 0.8 mm diam.; upper part c. 0.6 mm long, longer than the lower part, conical.

Follicles

Always one per flower, c. 60 × 12 mm, obclavate, round in cross-section, apically shortly beaked, wingless, dark brown, longitudinally grooved, glabrous.

Seeds

6-7 × 3.5-4 mm, ovate, dark brown; smooth on both sides, marginally with c. 0.3 mm wide wing with entire margin; coma c. 15 mm long.

REMARKS

Herbarium material of this species has been previously identified as Marsdenia oubatchensis (syn. M. pseudoparsonsia Guillaumin ) or M. microstoma . the linear-leaved M. mackeeorum , sp. nov. cannot be mistaken for the elliptical-ovate-leaved M. oubatchensis despite sharing very similar ovate-urceolate flowers. Vegetatively, the new species hardly differs from M. microstoma , from which it is distinguished by the bostrychoid inflorescences with a rachis that continues growth and flowering for long, whereas M. microstoma has sciadioidal inflorescences with all the flowers opening synchronously. In addition, long-ascending connective appendages, a conical style-head (broadly conical and depressed in M. microstoma ) and smaller caudicles make it possible to recognize this species.

Figures

FIG. 4. ─ Marsdenia mackeeorum Meve, Gâteblé & Liede, sp. nov.: A, branch with inflorescences and follicle; B, leaf in cross-section; C, inflorescence; D, flower in lateral view; E, flower in lateral view, the two proximal corolla lobes removed to show the gynostegium; F, pollinarium; G, style-head; H, seed. Drawings: U. Frensch from H.S. MacKee 38863 (P). Scale bars: A, 2 cm; B, C, 5 mm; D, 1 mm; E, 0.5 mm; F, G, 0.2 mm; H, 2.5 mm.

FIG. 3. ─ Distribution of the five new Neo-Caledonian Marsdenia R.Br. species.