Notopleura nivea (Sandwith) O.Lachenaud & Delprete, 2022

Lachenaud, Olivier & Delprete, Piero, 2022, Revision of Carapichea (Rubiaceae - Psychotrieae) in the Guianas, with two new combinations and transfer of three species to Notopleura, Plant Ecology and Evolution 155 (2), pp. 275-300 : 275

Notopleura nivea (Sandwith) O.Lachenaud & Delprete comb. nov.

Cephaelis nivea Sandwith, Bulletin of Miscellaneous Information, Royal Gardens, Kew 1939: 551 ( Sandwith 1939)

Psychotria nivea (Sandwith) Steyerm. ( Steyermark 1972: 556)

Carapichea nivea (Sandwith) C.M.Taylor ( Taylor and Gereau 2013: 121)

Type.

GUYANA - Potaro-Siparuni Region • Potaro River, Amatuk portage; 31 Aug. 1937; fl., fr.; Sandwith 1249; lectotype: K [2 sheets, K000174488, K000174489], designated here; isolectotypes: K [K000662774], K spirit collection n.v., NY [00131025] .

Description.

Perennial herb or subshrub, 18-30 cm tall (maybe more?), single-stemmed; distal internodes terete, 4-7 mm in diam., somewhat succulent, glabrous. Stipules consisting of a truncate sheath (absent at flower-bearing nodes) 3-9 × 7-10 mm, glabrous, persistent, and numerous basal linear appendages ca 2 mm long, aggregated into a dense mass, very early caducous, leaving a scar. Leaves with petioles 1.0-2.5 cm long, glabrous, drying black; blades elliptic to oblanceolate, 18-29 × 5.7-11.6 cm, acute-decurrent at base, obtuse to acute and acuminate at apex, acumen deltoid to narrowly triangular, 0.5-1.0 cm long, coriaceous to somewhat succulent when fresh, papyraceous when dry, drying greyish olive-green to brown above and pinkish to greyish pale brown or pale olive green below, glabrous throughout; secondary veins 12-19 on each side of midrib, embedded within the lamina, barely visible above and below in dried specimens; intersecondary veins (1-)2-3 between each couple of secondary veins, terminating far from the margin; tertiary veins invisible, embedded within the lamina; domatia absent. Inflorescence terminal, pedunculate, capitate; peduncles 2.5-5.3 cm long, glabrous, drying dark brown; head multiflorous, subtended by a cupular structure 1.0-2.5 cm long, made of 4 bracts connate at base; free portion of bracts decussate, unequal to subequal, broadly ovate, 1.5-2.6 × 1.5-2.5 cm, acute to obtuse at apex, fleshy, pure white, persistent, drying brown, with 3-5 ascending veins; bracteoles triangular-ovate, 0.7-2.0 × 0.2-0.5 mm. Flowers 5-merous, pedicellate; pedicels 1.8-2.5 mm long, fleshy. Hypanthium truncate-obconical, 0.6-0.7 mm long, glabrous. Disk bilobed to the base, 0.5-1.0 mm long, bipartite. Calyx 0.7-1.3 mm long, shallowly denticulate, glabrous; teeth broadly to shallowly triangular, 0.4-0.5 mm long. Corolla hypocrateriform, 17.7-21.5 mm long, glabrous, white with lobes yellow inside; tube narrowly cylindrical, 16-19 mm long, 1.3-1.5 mm wide, glabrous outside and inside; lobes ovate to triangular, 1-2.6 × 1-2.3 mm, acute at apex, glabrous outside, papillose inside. Stamens inserted at 9.5-12 mm from the base; filaments extremely short; anthers included, narrowly oblong, 3 × 0.3-0.4 mm. Style glabrous, included, 8 mm long; branches oblong, ca 0.6 mm long. Fruits oblong-ovoid, 5-6 × 3-3.75 mm, smooth (slightly costate when dry), colour unknown (pale olive-green when dry). Pyrenes semi-ellipsoid, 5-6 × 2 mm, strongly compressed dorso-ventrally, dorsal side with 4 prominent ridges, ventral side with 2 longitudinal grooves separated by an irregular median crest prolonged at apex into a short spine. Seeds unknown.

Distribution.

Endemic to Guyana and reported from the Potaro River Basin (Kaieteur Savanna, Amatuk Portage, and Hoit Mountain), the Upper Mazaruni River Basin (Ayanganna Plateau), and the Cuyuni-Mazaruni Region (W branch of Eping River).

Ecology.

Growing in understory of primary and secondary forests, sometimes on sandstone or white sands, on lowland and mountain slopes, at 274-610 m elevation.

Phenology.

Flowering specimens were collected in February, April-May, and July-August; and specimens with fruits only once in August.

Specimens examined.

GUYANA • Kaieteur Savanna; 1936; fl.; Hollister s.n.; NY • Upper Mazaruni River Basin , Ayanganna Plateau , between Pong River (686 m) and G.S. Camp 13, in Dicymbe forest , on trail to Ayanganna; 25 Jul. 1960; fl.; Tillett et al. 44925; NY • Potaro River Gorge , Amatuk Portage; 27 Apr. 1944; fl.; Maguire & Fanshawe 23018; K, NY • Cuyuni-Mazaruni Region, W branch of Eping River ; 7 Feb. 1991; fl.; McDowell & Stobey 3924; MO n.v ., US • Potaro-Siparuni Region, black water creek near Camp NW along ravine, rocky ravine, mixed premontane wet forest; 5°12'N, 59°10'W; 274-610 m; 23 May 1991; fl.; McDowell et al. 4901; MO n.v ., US • “Amutu” [Amatuk] Portage path; 20 Feb. 1879; fl.; im Thurn s.n.; K • Amatuk Falls, Potaro River ; 26 Aug. 1933; fl.; Tutin 600; BM • Potaro district , Hoit Mountain ; 2 Aug. 1959; fl.; Whitton 63; K .

Notes.

Sandwith (1939: 551-552), in the original description of Cephaelis nivea , cited the gathering Sandwith 1249 as the type, with no indication of the herbarium of deposit. Four sheets of this gathering have been found, three in K and one in NY, as well as one spirit collection (not seen by us) in K. According to the Code ( Turland et al. 2018), all these samples represent original material. One of the K sheets, barcode K000174488, which has complete label data and bears the annotation “Typus” in Sandwith’s handwriting, was cited as holotype by Taylor and Gereau (2013: 121-122). Being posterior to 2001, and not accompanied by the statement "here designated" or a similar expression, their citation cannot be treated as an inadvertent lectotypification (ICBN, Art. 7.11 & 9.10). Two sheets of Sandwith 1249 at K are labeled "Sheet I/II" (K000174488) and "Sheet II/II" (K000174489), and are physically kept together. Therefore, according Art. 8.3 of the Code ( Turland et al., 2018), they should be treated as a single specimen with multiple preparations. This specimen, composed of two sheets, is here designated as the lectotype of Cephaelis nivea.

Notopleura nivea differs from N. altsonii and N. sandwithiana by the characters summarized in Table 3 , the most obvious of which - not mentioned by Taylor and Gereau (2013) - is that the involucral bracts form a much longer basal cup than in the other two species. Taylor and Gereau (2013: 122) also reported differences in the colour of the bracts, which are apparently not constant, and in the colour of the corolla (supposedly purple in N. altsonii and yellow in N. nivea ) but in both species the corolla is actually white outside and yellow inside.