Ombrophytum guayanensis Delprete, 2014

Delprete, Piero G., 2014, Ombrophytum guayanensis, the first record of subfamily Lophophytoideae (Balanophoraceae) in the Guayana Shield, Phytotaxa 175 (5), pp. 263-269 : 264-267

Ombrophytum guayanensis Delprete , sp. nov. ( Figs. 1 and 2 ).

Type: — FRENCH GUIANA. Commune de Camopi , Upper Camopi River, Cacao Mountain, in undercanopy of forest 15–20 m tall, on lateritic soil, 02°21’18”N, 53°12’44”W, 200 m, 13 July 2012, G . leotard 1000 (holotype CAY!, isotypes K!, NY!, US!; material preserved in alcohol at CAY) .

Description and measurements made from specimens preserved in 60% ethanol and digital images. Total length of the plant 16−21 cm (including the tuber). Tuber subterranean, irregularly depressed-ellipsoid, 5−7 cm wide. Volva coriaceous, shape unknown (only the basal portion observed in an old individual), breaking off irregularly. Inflorescence bisexual, 13−16 cm long; lower sterile part short-cylindrical, 1−1.5 cm long, 2−2.5 cm in diam.; intermediate female part faintly ellipsoid, 6−9 cm long, 5−7 cm in diam. (including inflorescence branches); upper male part conical, 5−6 cm long, 3.5−4.5 cm in diam. at base (including inflorescence branches); surface of inflorescence axis among male branches conspicuously mammillate (somewhat ruminate in cross section), yellow when fresh. Bracts angular-clavate, vinaceous when fresh, regularly intermixed and emerging above male and female inflorescence branches, when these are not completely expanded (before anthesis); falling off before anthesis, leaving circular scars among inflorescence branches. Bracts intermixed among female branches 6−8 mm long (when female branches are 4−5 mm long); basal stalk truncate-obconical, 4−5(−6)-angular, 4.5−5 mm long, 1.3−1.5 mm wide at base and 2−2.5 mm wide just below the head; head irregularly hemi-ellipsoid to shallowly conical (without central protrusion), 3.5−4 mm wide, 2.5−3 mm thick. Bracts intermixed among male branches 6−8 mm long (when male branches are 3.5−4 mm long); basal stalk truncate-obconical, 4−5(−6)-angular, 3.5−4 mm long, 1.5−1.8 mm wide at base and 2.5−3.5 mm wide just below the head; head mammiform, 4.5−6 mm wide, 2.5−4 mm thick, the central protrusion with a tiny depression in the center. Female branches white to cream-white when fresh, 6.5−8 mm long during anthesis (9−12 mm long at fruiting stage), with 60−90 flowers densely arranged on the narrow, terete central branch; apical part peltately enlarged; pelta 7−8.5 mm in diam. during anthesis (9−12 mm in diam. during fruiting stage), irregularly crenate-dentate, fleshy when fresh. Female flowers without perianth; ovary obconical- to parallelepipedal-prismatic (due to mutual pressure), 1.8−2.2 mm long, 1.2−1.4 mm wide at truncate top; styles 2, appearing from a shallow pit at the truncate apical part of the ovary, 0.6−0.7 mm long, stigma capitellate, 0.2 mm in diam. at tip (microscopically mammillate). Male branches white to cream-white when fresh, 3.5−4 mm long when young (with anthers not fully developed, and when female branches are in anthesis), 5−6 mm long during anthesis (withering at fruiting stage), with 10−12 decussately arranged flowers, inserted on the terete central branch; apical part peltately enlarged; pelta 3.5−4 mm in diam. during anthesis, irregularly crenate-dentate, fleshy when fresh. Male flowers with 2 stamens; filaments 0.1−0.2 mm long, anthers basifixed, ellipsoid, 1.5−1.6 × 1−1.1 mm, thecae equal in length. Fruit 1-seeded, parallelepipedal-prismatic (due to mutual pressure), 2.4−2.7 mm long, 1.2−1.5 mm wide at truncate top.

Etymology: —The specific epithet refers to the Guyana Shield, because this the first species of this genus found in this region.

Distribution, Habitat and Ecology: —The only material known of this species is from a locality near Cacao Mountain, not far from the source of the Camopi River, French Guiana, growing in the undercanopy of a forest 15−20 m tall, on lateritic soil, at the base of an inselberg. The specimens were collected from a population of about 15 individuals in an area of about 3−4 m ². Most of the individuals were at the end of fructification, some of them already in advanced stage of decomposition, and only one young individual at the blooming stage. The plants were originally discovered by L. Proux and V. Pelletier on 8 July 2012, and were preserved in alcohol by G. Leotard on 13 July 2012.

Phenology: —Individuals in flowering and fruiting stage were collected from the same population, in July 2012. As for blooming strategy, it was observed that the female flowers bloom before the male flowers of the same individual (protogynous). In the young individual studied, the female flowers were in anthesis, with receptive stigmas, while the male flowers were with the anthers still closed. In the older individuals, instead, while the male branches were with opened anthers and releasing pollen, the female branches were already bearing mature fruits, with the styles fallen off.

Suggested conservation status: —This species is known only from a single population of about 15 individuals in an area of about 3−4 m ². As explained above, members of the Balanophoraceae are rarely collected; therefore, it is difficult to establish their true geographic distribution. However, taking into consideration the small population observed (Criterion B2) and the small area of occupancy (Criterion D), this species should be treated as “Critically Endangered” (CR) following IUCN criteria ( IUCN 2001).

Taxonomic relationships: —The classical reference for identification of Neotropical Balanophoraceae is the monograph published by Hansen (1980). According to this treatment, Ombrophytum guayanensis is unique in the genus because of the shape of the bracts that are regularly intermixed among the male and female branches, and by the subsessile anthers (filaments 0.1−0.2 mm long).

As in all other species of the genus, the inflorescence bracts of Ombrophytum guayanensis are difficult to observe because they are readily caducous, as they fall off just after anthesis (leaving a circular scar among inflorescence branches; i.e., they are absent at fruiting stage); therefore, they are present only in young individuals. Only one young individual of this species was available, and it was possible to observe that in both male and female portions of the inflorescence, the bracts are angular-clavate, while in all other species of the genus they are peltate. In O. guayanensis , the bracts have a 4−5(−6)-angular, tronco-obconical basal stalk, and a fleshy, expanded head; additionally, their shape varies depending on their position in the male or female portion of the inflorescence. The bracts intermixed among female branches are 6−8 mm long (when female branches are 4−5 mm long), with a basal stock 4.5−5 mm long, 1.3−1.5 mm wide at base and 2−2.5 mm wide just below the head, with and fleshy, irregularly hemi-ellipsoid to shallowly obconical head, 3.5−4 mm wide and 2.5–3 mm thick ( Figs. 1B, 1 F−G, 2C); meanwhile, the bracts intermixed among male branches are 6−8 mm long (when male branches are 3.5−4 mm long), with a basal stock 3.5−4 mm long, 1.5−1.8 mm wide at base and 2.5−3.5 mm wide just below the head, and a fleshy, irregularly mammiform head, 4.5−6 mm wide and 2.5−4 mm thick, with a central protrusion ( Figs. 1B, 1 D−E, 2B, 2D).

According to the species descriptions available in Hansen’s (1980) monograph, Ombrophytum guayanensis is most similar to O. violaceum Hansen (1980: 58) , as they both have monoecious inflorescences up to 16 cm long, and male flowers decussately arranged on male branches; the previous differing from the latter principally by the angularclavate bracts (vs. peltate in all other species of the genus), male inflorescence branches with 10−12 flowers (vs. 4−8 flowers per branch in O. violaceum ), anthers 1.5−1.6 mm long (vs. 1−1.25 mm long), female inflorescence branches 6.5−8 mm long (vs. 4−6 mm long), ovary and fruit 2−2.5 mm long (vs. 1.2−1.5 mm long), and styles 0.6−0.7 mm long (vs. 0.5 mm long). A comparison of the main morphological differences of the five species of Ombrophytum , and their geographic distribution, is available in Table 1.

Figures

FIGURE 1. Ombrophytum guayanensis. A, habit of a young individual, with stalk and basal tuber; B, longitudinal section of the young individual, showing the basal stalk, the intermediate female part with female branches intermixed among bracts, and the upper male part with male branches intermixed among bracts; C, individual in advanced stage, with female branches with mature fruits (not visible, present below the pelta); D, portion of the male part of the young individual, with two bracts and two immature male branches; E, male branches in anthesis, with dehisced anthers; F, portion of the female part of the young individual, with two bracts and two female branches in anthesis (stigmas receptive); G, Female branch with mature fruits; H, female flower in anthesis, with detail of the receptive stigma; J, mature fruit. (D−E at same scale, F−G drawn at same scale, H−J drawn at same scale). Drawn by P.G. Delprete from type specimens preserved in alcohol.

FIGURE 2. Ombrophytum guayanensis. A, habit of a young individual, with cross sections of female and male portions; B, Side view of a cross section of a male portion, with two female branches at base (see too bigger pelta al base); C, detail of the cross section of the female portion of the young individual, with female flowers in anthesis; D, detail of the cross section of the male portion of the young individual, with undevelopped male branches and very young anthers; E, individual in advanced stage, with female branches with mature fruits (present below the pelta). Photos by G. Leotard.