Paramollugo digyna (Montrouz.) Sukhor, 2016

Sukhorukov, Alexander P. & Kushunina, Maria, 2016, Taxonomic revision and distribution of herbaceous Paramollugo (Molluginaceae) in the Eastern Hemisphere, PhytoKeys 73, pp. 93-116 : 102

Paramollugo digyna (Montrouz.) Sukhor comb. nov.

Mollugo digyna Basionym; Montrouz., Ann. Acad. Roy. Sci. Lyon, Sect. Sci. 10: 179 (1860).

Neotype

(Sukhorukov, selected here). NEW CALEDONIA. West face of Massif de Koniambo, 300 m, iron-serpentine scrub on track through “maquis”, 11 October 1963, P.S. Green 1287 (K001045648!).

Discussion.

This taxon described by X. Montrouzier was completely forgotten and cited as Mollugo nudicaulis in the treatments of the New Caledonian flora (e.g., Guillaumin 1948, Rageau 1973). However, Paramollugo digyna is easily recognized by unique reniform or even triangular leaf blades (Fig. 7 ), and by a tendency to become a short-lived perennial (in contrast to annual Paramollugo nudicaulis ). Unfortunately, many specimens were collected without the basal portion or in their first growing season, and it is still unclear which life form is predominant in Paramollugo digyna . Neither perennial habit nor unusual leaf shape were mentioned in the protologue ( Montrouzier 1860), but the author indicated the presence of two-valved capsules. We also found that the specimens collected in New Caledonia have two- or rarely three-valved capsules with 8 or fewer seeds, in contrast to other herbaceous Paramollugo , which are characterized by capsules with three locules and up to 30 seeds. The outer walls of the testa cells are elongated, almost rectangular, with secondary warty outgrowths. A similar seed surface was observed in the Caribbean Paramollugo navassensis and is clearly distinct from Paramollugo nudicaulis ( Sukhorukov and Kushunina in press, sub Mollugo ).

No original material of Paramollugo digyna was traced. The herbarium of X. Montrouzier, who described Mollugo digyna , is located in University of Montpellier herbarium (MPU), with some duplicates in the National Museum of Natural History, Paris (P). Only one specimen of Paramollugo digyna was found, without a precise location (MPU-310526). No specimens are cited in the protologue ( Montrouzier 1860). The sheet found in MPU (no. 169) and dated 1866 might have been collected later, and hence cannot be considered as original material. However, the plant clearly originates from New Caledonia due to the writing on the sheet "Stylos binos semper, capsulamque bivalvam vidi!" ("stylodia always two, capsule two-valved"). Since the original material is not found (Art. 9.16 of ICN) here we select a neotype that bears a plant with perennial life form, reniform leaves and two-valved capsules as the most indicative characters of Paramollugo digyna .

Paramollugo digyna is known only from New Caledonia where it usually grows on rocky or stony substrates; locally common ( Guillaumin 1964 sub Mollugo nudicaulis ). Paramollugo nudicaulis s.str. is not present in New Caledonia.

Examined specimens

(selected specimens). NEW CALEDONIA: Kanala [Canala], 1859-1860, Viellard (BR); [no precise location] 1861-1867, Viellard 120 (K); [no precise location] 1870, Pancher 236 (BM, K, P04583449); Canala, 2000 ft, 17 February 1914, Compton 1251 (BM); Lower slopes of Mt. Kafeate, 30 March 1956, stony ground, H.S. McKee 4228 (E, K).

Figures

Figure 7. Paramollugo digyna. A general habit B leaf rosette C flower D inflorescence. Photographs by Julien Barrault.