Marsdenia kaalaensis 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 : 56-60

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

( Figs 1A ; 2 ; 3 )

Dwarf shrubs with suborbicular leaves that are florally most similar to the linear-leaved twiner M. neocaledonica , sp. nov. but possessing longer pedicels (7-14 mm long vs 3-6 mm long in M. neocaledonica , sp. nov.), triangular corona lobes c. 1 mm long (vs ovate, 0.5 mm long in M. neocaledonica , sp. nov.), anther appendages 500 µm long, erect and parallel to the elongated-conical, rostrate style-head (vs 375 µm long, appressed to the broadly conical style-head in M. neocaledonica , sp. nov.).

TYPUS. — New Caledonia. Grande-Terre, North Prov., Kaala- Gomen , Mount Kaala , 164°23’22”E, 20°37’6”S, 920 m alt., in maquis among peridotites, 7.XII. 2005, fl., Y. Pillon, R. Barrière & F. Rigault 213 (holo-, P [ P05208158 ]! ; iso-, NOU [ NOU009225 ]!) .

PARATYPI. — New Caledonia. Grande-Terre, North Prov.: Koumac/Kaala-Gomen limit, crest between Pic Pandop and Mount Kaala , 700 m alt., in degraded maquis vegetation on eroded laterites, 14.XI.2005, G. Dagostini, F. Rigault & R. Barrière 1088 ( NOU020355 ) ; Kaala-Gomen , top of Mount Kaala , 21.VI.1966, A. Nothis 200 ( NOU017720 ) .

ETYMOLOGY. — Marsdenia kaalaensis , sp. nov. is named after the massif of Kaala, where it grows and of which it is a micro-endemic or a narrow endemic species restricted to one location (NES 1) according to the definition of Wulff et al. (2013).

DISTRIBUTION AND HABITAT. — New Caledonia. Grande-Terre, North Prov., Kaala-Gomen and Koumac, Mont Kaala ( Fig. 3 ).The species is strictly confined to more or less degraded maquis vegetation on lateritic soils or between peridotites blocks and grows between 700 and 1000 m altitude.

CONSERVATION STATUS. — So far, the only known locality of this new species is on the top of the Kaala massif in the northwest of the main island of New Caledonia. The Kaala massif is especially rich in endemic plant species of different plant families with seven micro-endemic species reported to occur only there ( Wulff et al. 2013). Mount Kaala is not a protected area and is facing a major impact from nickel mining activity especially the top of the mountain where this new species occurs. The whole predicted area suitable for the ecology (Mount Kaala between 700 and 1000 m altitude) of M. kaalaensis , sp. nov. is under mining concession belonging to two different mining companies. At the moment, M. kaalaensis , sp. nov. is only reported from the middle part of the Kaala, and there from the crest south of Piton de Pandop for the northern population and around the Kaala peak for the southern population; the whole area belonging to Société des Mines de Tontouta concessions. Thus, it is considered as a single location (sensu IUCN) with an EOO and an AAO of 4 km 2. The species is uncommon in the locality (cf. Pillon et al. 213) and a whole day search in the three previously reported places by three people did not locate it again on 27 April 2016. Marsdenia kaalaensis , sp. nov. is assigned a preliminary IUCN conservation status of “Critically endangered” [CR B1ab(ii,iii,v)+2ab(ii,iii,v)] using Red List criteria ( IUCN 2012).

DESCRIPTION

Plants

Compact, erect shrubs to 30 cm high, non-twining, branched, often trailing.

Shoots

Perennial, woody, with scattered trichomes when young; internodes 5-15 mm long, 1.5 - 3 mm diam.

Latex

Colour unknown.

Leaves

With petiole 10-30 mm long, spreading to ascending, pedicels 2 - 5 mm long, canaliculate above, with scattered trichomes when young, leaf blades without basal colleters, plain, stiff and coriaceous, 8 - 25 mm long, 7 - 17 mm wide, (broadly elliptic-) suborbicular, basally rounded, apically rounded but usually mucronate, glabrous, discolorous, adaxially dark green, abaxially bright green, with protruding rachis.

Inflorescences

Always one per node, extra-axillary, subsessile to shortly pedunculate, 2 - many-flowered, sciadioidal, flowers open synchronously and in succession. Peduncles 0-1.5 mm long, persistent, glabrous or nearly so.

Flowers

Floral bracts broadly elliptic, less than 1 mm long, scattered hirsute (ciliate). Pedicels 7 - 14 mm long, glabrous or nearly so, bright green, occasionally spotted dark red. Flower buds c. 2 × 2 mm when mature, ovoid-globose.

Calyx

Free-lobed, glabrous, sepals c. 1.5 mm long, 1 mm wide, ovate, apically obtuse.

Corolla

Rotate-campanulate, 3 - 4 mm long, abaxially yellowish, adaxially bright yellow (occasionally with purple zones), glabrous; lobes fused for about a quarter of total corolla length, 1.5 - 2 mm long, 1.3 - 1.5 mm wide, horizontal to ascending, oblong, apically obtuse.

Gynostegial corona of staminal lobes (Cs)

Basally fused to each other to form a ring-like structure, yellowish, glabrous, c. 1 mm high, 1.5 mm diam., shorter than the gynostegium;staminal corona lobes spreading to erect, c. 0.7 mm long, 0.6mm wide at base,solid, deltoid, adaxially with a central depression, with thickened, recurved margins and recurved tips.

Gynostegium

c. 1.5 mm high, 1 mm diam., elevated by a very short column; anthers twice as high as broad, c. 1.5 mm long, rectangular; anther wings c. 300 µm long, extending along two thirds of anther length, consisting of distal ridge alone; adjacent anther wings parallel to each other in upper half, spreading in lower; connective appendages foliaceous, erect, c. 500 µm long, 400 µm wide, rectangular, shortly tipped.

Pollinarium

Corpusculum c. 200 µm long, 65 µm broad, elliptic; caudicles c. 60 µm long, cylindrical, with a s-shaped bent, basally inserted at the corpusculum; pollinia basally attached to the caudicles, erect, c. 300 µm long, 90 µm wide, ovate in crosssection, oblongoid.

Style-head

c. 0.7 mm long, 0.6 mm diam., elongated-conical, rostrate, rostrum 0.3 - 0.4 mm long.

Fruits and Seeds

Not seen.

REMARKS

The new species makes an unusual sight, not only for Marsdenia in New Caledonia, with its low but compact shrubby habit and the condensed foliage of suborbicular, stiff and spreading leaves. In contrast, the flowers of Marsdenia kaalaensis , sp. nov. are not very spectacular except for their long pedicels that can reach 14 mm and surpass in length all New Caledonian Marsdenia species. A corona that is basally fused to form a ring-like structure spanning the interstaminal positions is found in other species as well (e.g. M. neocaledonica , sp. nov., M. tylophoroides ) and elongate-conical and rostrate style-heads are also not unique ( M. lyonsioides , M. speciosa ). However, the conspicuously erect and foliaceous anther appendages are diagnostic for M. kaalaensis , sp. nov. alone. With regard to Asclepiadoideae , two other Marsdenia species are known from this locality, namely the frequent M. microstoma Schltr. , and M. oubatchensis Schltr.

Figures

FIG. 1. ─ A, Marsdenia kaalaensis Meve, Gâteblé & Liede, sp. nov., flowering at the type locality at Mt. Kaala, 20.X.2007 (Photo: J. Munzinger); B, C, Marsdenia neocaledonica Meve, Gâteblé & Liede, sp. nov., flowering in ultramafic maquis at Katepaik mountain, 4.V.2015 (Photo: Hervé Vandrot); D, Marsdenia paulforsteri Meve, Gâteblé & Liede, sp. nov. in habitat at Mt. Dzumac, 26.I.2010 (Photo: G. Gâteblé); E, Marsdenia paulforsteri, sp. nov. in cultivation (Photo: G. Gâteblé).

FIG. 2. ─ Marsdenia kaalaensis Meve, Gâteblé & Liede, sp. nov.: A, flowering stem; B, flower in top view; C, gynostegium with corona in lateral view; D, isolated style-head with still one pollinarium attached; E, pollinarium. Drawings: U. Meve from Pillon et al. 213, Fig. 2A drawn after a photograph taken by J. Munzinger. Scale bars: A, 5 mm; B, 2 mm; C-E, 0.2 mm.

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