Carapichea tillettii (Steyerm.) C.M.Taylor (Taylor and Gereau 2013: 123)

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

8. Carapichea tillettii (Steyerm.) C.M.Taylor (Taylor and Gereau 2013: 123)

Psychotria tillettii Steyerm. ( Steyermark 1972: 496, figure 70)

Type.

GUYANA • Upper Mazaruni River basin, Partang River, ridge of Merumé Mountains; 1140 m; 1 Jul. 1960; fr.; S.S. Tillett et al. 43946; holotype: NY [0013844], isotypes: COL [COL000004671], F [No. 1704833, 1704834], K [K000432817, K000432818], NY [0013845], P [P02428007] , US [00131318, 00146632], VEN [No. 82283].

Description.

Shrub or treelet 1-3 m tall; terminal branchlets terete to slightly quadrangular, 4.0-5.5 mm in diam., glabrous, soon covered with a buff corky bark. Stipules shallowly sheathing at base, 3.5-8.0 × 5 mm, broadly ovate, glabrous, bilobed or irregularly fimbriate at apex, with lobes 1-5 mm long, soon corky and marcescent. Leaves opposite or ternate; petioles 1.5-3.0 cm long, glabrous; blades narrowly elliptic or oblong-elliptic, 14-25 × 5-10 cm, acute to decurrent at base, acute and long-acuminate at apex, acumen narrowly triangular to linear, 1.0-2.5 cm long, coriaceous, drying olive green above and yellowish green below, glabrous throughout; primary and secondary veins prominent on both sides; secondary veins 8-12 on each side of midrib, curving towards the margin and almost reaching it; tertiary venation densely and prominently reticulate in the dry state; domatia absent. Inflorescence thyrsoid, rather narrowly pyramidal, long-pedunculate (expanded at fruiting stage); peduncles 7.5-12.5 cm long, glabrous, drying brown; secondary branches whorled, 3-5 per node, spreading, 0.4-2.0 cm long (0.8-4.0 cm at fruiting stage), glabrous except fringes of hairs at nodes, terminating into cymules; cymules with 15-22 flowers; bracts 4-5 around each cymule, ovate to triangular, 1-4 × 0.7-2.0 mm, obtuse to rounded at apex, slightly concave, persistent, drying brown, glabrous except a row of hairs at the base inside. Flowers 5-merous, heterostylous, sessile. Hypanthium narrowly obovoid, 0.5-1.0 mm long, glabrous. Disk bilobed to the base, ca 1 mm long. Calyx cupular, 0.7-1.0 mm long, truncate or minutely denticulate, glabrous. Corolla hypocrateriform, 8-10 mm long, white, greenish-white or brownish-white; tube narrowly obconical to almost cylindrical, 6.0-6.5 mm long, 1.0-1.5 mm wide at base, 1.5-4.0 mm wide at mouth, glabrous outside, pubescent in distal portion inside; lobes lanceolate to triangular, 1.5-3.5 × 1.0-1.3 mm, acute at apex, glabrous. Short-styled flowers: stamens exserted, filaments 2.5 mm long, anthers narrowly oblong, 1.8 mm long; style included, 2.5 mm long, glabrous. Long-styled flowers: stamens included; style exserted, 8 mm long, shortly bifid, glabrous. Fruits ellipsoid to ovoid or subglobose, 7-10 × 5-8 mm, costate when dry, dark red or maroon (probably when immature) to purplish-black. Pyrenes plano-convex, elliptic to oblong in outline, 6-9 × 4.5-6.0 mm, dorsal side 3-4-costate, ventral side longitudinally sulcate. Seeds entire, C-shaped in cross-section.

Distribution.

Endemic to western Guyana, Potaro-Siparuni and Cuyuni-Mazaruni Regions, on Merume Mountains, Mount Ayanganna, and Mount Wokomung, which are the easternmost extensions of the Pakaraima Mountains.

Ecology.

Growing in dense scrub forest on tepui sandstone, at 1070-1570 m elevation.

Phenology.

Flowering specimens were collected in June and July, and fruiting specimens in February, March, June, and July.

Selected specimens examined.

GUYANA • Potaro-Siparuni Region, Ayanganna Slope; 2 Mar. 1960; fr.; R. Browne 118 (Forest Department of British Guiana No. 7942); NY • Potaro-Siparuni Region, Mount Ayanganna , E face, camp above first of four escarpments; 5°20 ’19” N, 59°56 ’46” W; 1070 m; 12 Jun. 2001; fl., fr.; Clarke et al. 9062; MO n.v ., US; ibid., Clarke et al. 9063; MO n.v ., US • Potaro-Siparuni Region, Mount Ayanganna , E face, plateau above third of four escarpments; 5°23 ’12” N, 59°58 ’36” W; 1570 m; 19 Jun. 2001; fr.; Clarke et al. 9350; MO n.v ., US • Potaro-Siparuni Region, Mount Ayanganna , E face; 5°23 ’05” N, 59°58 ’33” W; 1545 m; 26 Jun. 2001; fl., fr.; Clarke et al. 9565; MO n.v., NY , US • Potaro-Siparuni Region, Mount Wokomung , easternmost pinnacle of massif; 5°05 ’34” N, 59°50 ’13” W; 1524 m; 30 Jun. 2003; fl. buds; Clarke et al. 10341; MO n.v., NY , US • Potaro-Siparuni Region, Mount Wokomung , base of fourth escarpment; 5°05 ’39” N, 59°50 ’36” W; 1375 m; 4 Jul. 2003; fr.; Clarke et al. 10508; MO n.v., NY , US • Potaro-Siparuni Region, Mount Wokomung, Little Ayanganna, summit of highest point of Mount Wokomung massif; 5°04 ’53” N, 59°50 ’26” W; 1660 m; 6 Jul. 2003; fl.; Clarke et al. 10588; MO n.v., NY , US • Potaro-Siparuni Region, Mount Wokomung , summit; 5°04 ’3” N, 59°51 ’42” W; 1560 m; 10 Jul. 2003; fl. buds; Clarke et al. 10713; MO n.v ., US • Potaro-Siparuni Region, Mount Wokomung , summit; 5°04 ’03” N, 59°51 ’42” W; 1560 m; 10 Jul. 2003; fl. buds; Clarke et al. 10757; MO n.v ., US • Potaro-Siparuni Region, Pakaraima Mountains, Mount Wokomung , summit plateau, from central plateau 1-2 km to escarpment; 5°04'N, 59°52'W; 1500-1530 m; 19 Feb. 1993; fr.; Henkel & Chin 1483; MO n.v., NY , US, Mount Ayanganna , east slope; 13 Mar. 2014; fr.; Radosavljevic et al. 146; P .

Notes. This species was placed by Taylor and Gereau (2013) in their Panurensis group, together with C. panurensis from Brazilian and Colombian Amazon, but the two differ in so many characters that a close relationship between them seems unlikely. In fact, C. panurensis has several aberrant characters within the genus: almost spiciform inflorescences (the lateral branches being extremely reduced), an entire disk, large mitriform stipules usually with a prominent midrib, and secondary leaf veins forming conspicuous loops far from the margin. On the other hand, C. tillettii has thyrsoid inflorescences, a bipartite disk, stipules smaller than those of C. panurensis and without prominent midrib, and secondary leaf veins looping near the margin. All these characters fit very well with Taylor and Gereau’s (2013) Carapichea group, where C. tillettii most closely resembles C. franquevilleana and C. klugii . It differs from these species (which are probably not distinct from each other) by its pyramidal inflorescence with ramifications shorter than rachis (vs not or hardly so), smaller and coriaceous bracts, corolla tube 6.0- 6.5 mm long (vs 3 mm long), and sessile fruits (vs shortly pedicellate). As noted by Taylor and Gereau (2013), the leaves of C. tillettii may be opposite or verticillate, sometimes with both conditions on the same branch, and the stipules can be bilobed or irregularly 3-5-fid at apex. The locality, altitude, collection date, and field notes of the type collection have been wrongly cited both in the protologue ( Steyermark 1972: 498) and in Taylor and Gereau (2013: 123). The type label actually reads "Tree to 3 m; flowers white; fruit dark red; occasional in wet forest along trail, ridge of Merume Mountain, elev. 1140 m.". This species is not to be confused with Rudgea tillettii Steyerm. (Steyermark 1976: 416), which is a synonym of R. coussareoides (Standl.) C.M.Taylor, Bruniera & Zappi ( Taylor et al. 2015). The latter somewhat resembles C. tillettii in general appearance, but its stipules are basally connate into a truncate sheath and bearing dorsal appendages (these soon caducous), its flowers are sparsely arranged (not densely crowded at the apex of inflorescence ramifications) and its disk is entire.