Rhipsalis micrantha subsp rauhriorum

R. roseana HBG*

R. micrantha ssp rauhriorum

R. roseana HBG

*Huntington Bot. Gdn

See Calvente thesis 2010
7.3. Rhipsalis micrantha subsp. rauhiorum (Barthlott) Calvente, stat. nov.
Rhipsalis rauhiorum Barthlott, Trop. Subtrop. Pflanzenwelt 10: 15. 1974.
Rhipsalis micrantha f. rauhiorum (Barthlott) Supplie, Rhipsalidinae: 101 . 1994. Rhipsalis micrantha f. rauhiorum (Barthlott) Barthlott & N.P.Taylor, Bradleya 13:62. 1995.-TYPE: ECUADOR. "tal des Rio Catamayo", 1300 m, Sept. 1973, Rauh 35278 (holotype: HEID702584!; isotype: HEID702585!, HNT!).

Terrestrial or rare epiphyte in sunny habitat, 0.8 m long, branching apical or sub-apical. Stem segments flattened to triangular, rarely quadrangular in longitudinal section, 1.5-3 mm diam, olive green, succulent, monomorphic, 5-14 cm long, base attenuate, apex truncate; wings 2-3(-4), sometimes discontinuous, 0.4-1 cm wide, margin crenate, plane, with 1-4 mm projections, midrib 3-4 mm diam, cylindric. Areoles between margin projections, 1-3.5 cm apart, first of segment 1-5 distant from segment base; when sterile 2 mm diam, with vestigial scales; when fertile 1.5 mm diam, with 1-2 acicular scales and scarce hairs at margin, 1(-2) flowers/fruits. Flowers ca. 9.5 mm diam; pericarpel 3-3.5 X 2.5-3 mm, cylindric, greenish, glabrous or with sepaloid bract; with 1-3 sepaloid tepals, 0.3-1.2 mm long and 7 petaloid tepals, 4-5 X 2.3-2.7 mm, oblong to ellptic, patent or sub-erect, greenish yellow, apex rounded, slightly cucullate to straight, margin straight. Style 4 mm long; stigma with 4-5 lobes, 1.5 mm long, ligulate, curved, sub-reflexed. Ovules in 4 rows, funicle short (< 0.5 mm long). Stamens ca. 40, 1.5-3.5 mm long, internal shorter, internal facing outwards and external facing inwards, whitish. Nectary ca. 0.5 mm. Fruit 7 X 5-6 mm, globoid, whitish, sometimes with reddish apex, glabrous. Figure 7: F, K.

Notes. Rhipsalis micrantha subsp. rauhiorum is distinct from the other four subspecies of Rhipsalis micrantha by the wider wings with margins with deeper projections.

Habitat and distribution: This species is restricted to the Catamayo River Valley, in Loja (Ecuador), occurring in mostly arid formations, ranging from 1600-1700 m. Figures 8, 9.

Rhipsalis rauhiorum BARTHLOTT, Trop. Subtrop. Pflanzenw. 10: 15. 1974
Now treated as a form of R. micrantha in Bradleya 13/1995
Note to the title : This species is named after WERNER and HILDE RAUH, who discovered it during a joint excursion in the valley of the Rio Catamayo (South Ecuador) in September 1973

Plant epilithic, hanging over, bushy, up to 1 m long, branching richly acrotonically (occasionally also mesotonically); sometimes building whorls.
Shoots 2-sided (primary branches 3- to 4-sided), leaf-like flattened, succulent. Shoots strongly crenate, 1,9-2,2 cm wide and 5 – 10 cm long with yearly determinate growth (pic 10-12).
Areoles very small, without bristles and with barely visible tomentum; only new growth with insignificant delicate deciduous leaf .
Branch epidermis dull green with ca. 70 x 100 µ big cells and smooth surface; stomata not sunken.
Flowers lateral on younger shoots, single or sometimes with two, whitish (because of the sometimes intensive colored disc often with a red centre), radial, 7-11 mm in diameter and 8-9 mm long.
Petals 5 to 9, whitish transparent, elongated acuminate, the innermost up to 5 mm long and 2,5 mm wide.
Style erect, 4 mm long, with mostly 4 back curved lobes. At the base of the flower a well formed, whitish to mostly carmine disc. Stamens 25 to 35, 2-3,5 mm long, anthers small, whitish.
Pollen 6- to 8-colpat, round, ca. 50µ diameter (pic. 22); Colpi ca. 20 µ long. Exine (pic. 25) closer as with Rh. micrantha (HBK)DC with ca. 0,3µ long spinules, near (or next to) the regular superficial punctures with irregular tectal perforations.
Pericarp lightgreen, naked, only seldom with vestigial areoles, not sunken in the stem.
Fruit a spherical, naked, ca. 7 mm long and 5,5 mm thick, dirty white berry, often with a red overlay.
Seeds ca. 25-35 per berry, blackbrown, elongated oval, ca. 1,4 mm long and 0,6 mm broad with a basal oval hilum. Testa completely smooth with ca. 90 – 150 µ long and 40 µ wide cells without secondary structure (pic. 17b).
Chromosomes 2n=22 (extracted from root ends).
Habitat : epiphytic on old trees in raingreen Ceiba pentandra forest of the Rio Catamayo valley (South Ecuador) at 1300 m altitude;
Holotype : RAUH & BARTHLOTT No. 35278 in the herbarium of the Institutes für Systematische Botanik der Universität Heidelberg. Clonotypes are to be founded in culture in the Botanical Garden of the University of Heidelberg, the succulent collection of the city of Zurich and in some other collections.

Rhipsalis rauhiorum is a very remarkable species, which in its habitat reminds of Zygocactus truncatus. The specimens that have been collected in Ecuador in September, have flowered abundantly in culture in December. In its habitat the species is accompanied by xeromorph Bromeliaceae like Vriesea espinosa, V. barclayana, Pitcairnia spec. (aff. P. pungens), Tillandsia capillaris, T. disticha, T. latifolia var divaricata, and others. Rh. rauhiorum appears to be a very variable species. From East Ecuador we obtained a remarkable, very elegant form with rose-coloured berries (RAUH & BARTHLOTT 34737); it was found at an altitude of 1000 m near Puyo (Oriente) by JOEL BRENNER. A very divergent form with longer, leaf-like flattened stems grows in North Peru on the west slopes of the Andes, between 1200 and 1700 m altitude, near the road to Ayabaca, epiphytic on old trees (pic. 9) and on Gymnocereus (Browningia) microspermus (RAUH & BARTHLOTT No. 35307 and 35308).

Rhipsalis roseana BERGER from Columbia and Costa Rica is to be considered as a closely related species,. According to its original diagnosis and the cultivated Columbian plants (BG HEID No 35981 from the MARNIER-LAPOSTOLLE collection) this species distinguishes itself by its smaller and thinner stems and the form of the flowers as well as by the colour of the ripe fruit. Rh. rauhiorum is – compared to Rh. roseana – a xenomorph habitant of the (for the genus Rhipsalis) extreme dry biotopes. On the other side it appears to go from Rh. rauhiorum via the larger, flattened intermediate forms to Rhipsalis goebeliana (HORT.?) BACKBG., which up to now was only known in culture. Here we can find probably the origin of the subgenus Phyllorhipsalis.