Boyania kenwurdackii Michelang., 2022

Boyania kenwurdackii Michelang. View in CoL sp. nov. FigS. 1 View Fig & 2 View Fig

Differs from Boyania ayangannae Wurdack by the 4-merous ( vs. 5-merous) flowers, hypanthia sparsely covered by minute sessile glands ( vs. densely to sparsely glandular pubescent), smaller petals (up to 3.24 mm long vs. 8–13 mm long), and anthers with a bilobed ventral appendage 0.15 mm long ( vs. a single dorsal appendage 0.6 mm long), and the larger dorsal appendage ( 1.4–2.2 mm vs. 0.8–1.2 mm long).

Type: GUYANA, Cuyuni-Marazuni, 2nd and 3rd escarpments (of four) of Kamakusa Mt. , upper west-facing slopes below summit, 1330 m, N 5°52’55.2”, W 60°06’34.6”, 08.06.2012 (fl), K. J. Wurdack, E. A. Tripp, A. Radosavljevic GoogleMaps &

J. Ralph 5869 (holo NY [ NY 04239396!]; iso K [K000370697], P [P00950851!], US [ n.v.]).

Creeping to climbing herbs to small shrub, terrestrial or growing on fallen trunks or rocks, adventitious roots occasionally present. Stems obscurely quadrangular to flattened when young, glabrescent to pubescent, the trichomes mostly eglandular, but mixed with some glandular, 0.7–1.1 mm long, appressed, the older stems glabrescent and terete, nodes with a membranous, irregular flap c. 1.3 mm wide. Leaves opposite, usually isophyllous, occasionally anisophyllous, then the smaller leaf 1/3-1/5 the size of the larger one; petioles in isophyllous nodes or large leaves 3–8 cm long and up to 3.5 mm across., in smaller anisophyllous leaves 5–12 mm long, in all cases densely pubescent, trichomes simple, up to 2.5 mm long, appressed; leaf blades ovate to elliptic, 6.5–13 × 3.8–8.5 cm, chartaceous, base obtuse to broadly acute, apex acute to acuminate, margins serrulate and sparsely ciliate, the trichomes simple, up to 1 mm long; abaxial surface with sparse minute sessile glands, the primary and secondary veins pubescent, trichomes up to 0.8 mm long, appressed, mostly eglandular, but with some glandular trichomes, higher order veins with mixed minute sessile glands and simple trichomes up to 0.2 mm long; adaxial surface with sparse minute sessile glands, otherwise glabrescent or dense to sparsely strigulose with smooth trichomes up to 0.8 mm long; venation acrodromous with 2–3 pairs of secondaries basal, the outer pair considerably thinner, tertiary veins straight, spaced every 3–5 mm, higher order veins forming areolae 2–4 mm wide. Inflorescence terminal, with a 4–9 cm long peduncle, with a pair of bracts near the middle, glabrous, with 3–4 verticillate branches, each of them a scorpiod cyme; bracteoles lanceolate, 2–3 mm long, margins ciliate at the apex, persistent in flower, but late caducous; pedicels 3–4.5 mm long at anthesis, up to 13 mm long in fruit. Flowers 4–merous; hypanthium campanulate, 2.5–3 mm long, 2.1–2.3 mm wide at the torus, sparsely covered by minute sessile glands. Calyx 1.6–1.8 mm long; tube c. 8 mm long, lobes broadly deltoid with a blunt slightly cucullate apex, 0.8–1 mm long, the outer tooth reduced to a stubby round bump, the outer surface with glands similar to the hypanthium. Petals 3–3.2 mm long, thin and translucid when dry. Stamens 8, isomorphic; filaments 2.5–2.8 mm long, glabrous; anthers subulate and slightly arcuate, 2.1–2.2 mm long, opening by a minute pore, upright to slightly dorsally oriented, connective not prolonged belong the thecae, but with a dorsal flattened appendage 1.4–2.2 mm long, and two ventral appendages c. 0.15 mm long. Ovary fully to ½ inferior, 4– locular, with a collar c. 0.9 mm tall around the style, glabrous; style straight, projecting 2.5–2.8 mm above the collar; stigma punctiform. Fruit capsular, terete but with 8 prominent ridges; seeds numerous (>50) per fruit, long pyramidal, 0.6–0.7 long, testa cells flat and with the anticlinal walls puzzle-shaped.

Flowering & fruiting: Flowering and fruiting plants have been collected in both in March and June, but there are no collections outside of these months.

Habitat: Boyania kenwurdackii grow in the understory of moist forests in the foothills and mid elevations of the Pakaraima mountains of the Guayana Shield in central Guyana at elevations between 225 m and 1330 m ( Fig. 3 View Fig ).

Distribution: Endemic to Guyana.

Etymology: The specific epithet honors Ken Wurdack, Curator at the National Museum of Natural History of the Smithsonian Institution, who has collected in some of the most remotes corners of Guyana, including the type of this new species.

Specimens examined: Boyania kenwurdackii

Michelang: GUYANA, Potaro-Siparuni. Kaieteur National Park, upper Mure Mure basin, 480–490 m, N 5°16’19.56”, W 59°30’53.28”, 25.03.2014 (fl.), F.A. Michelangeli & N. Zarine 2486 ( BRG, NY, US) GoogleMaps ; Marina Falls , 449 m, N 5°22’43.2”, W 59°29’33.3”, 28.03.2011 (fl.), C.E. Zartman, M.M. Pombo, Y.H. Glen & C. Perry 9356 ( INPA) GoogleMaps ; Amalia Falls to V 4, 225 m, N 5°20’40”, W 59°32’06”, 30.03.2011 (veg.), C. E. Zartman, M.M. Pombo, Y.H. Glen & C. Perry 9368 ( INPA, US) GoogleMaps ; Ibid . , 30.03.2011 (fl.), C.E. Zartman, M.M. Pombo, Y.H. Glen & C. Perry 9387 ( INPA, US) ; V4, N 5°22’40”, W 59°32’00”, 31.03.2011 (fl.), C.E. Zartman, M.M. Pombo, Y.H. Glen & C. Perry 9404 ( INPA, US) GoogleMaps . Boyania ayangannae Wurdack : GUYANA, Cuyuni-Mazaruni, Pakaraima Mts, ascent and transect 4 km along NE plateau of Mt. Ayanganna , 1100–1500 m, N 5°24’, W 59°57’, 06.11.1992 (fl buds), T.W. Henkel 147 ( BRG, NY, US) GoogleMaps ; Pakaraima Mountains, Kumarau Falls on Kurupung River , 0.5–1.5 km SW on forest trails, 350 m, N 6°05’, W 60°21’, 31.07.1992 (veg), B. Hoffman 2237 ( NY, US) GoogleMaps ; Pakaraima Mountains; ascent and transect 4 km along NE plateau of Mt. Ayanganna , 1100– 1500 m, N 5°24’25”, W 59°57’13”, 06.11.1992 (fr), B. Hoffman 3236 ( NY, US) GoogleMaps ; Pakaraima Mountains ; 1–4 km NW of Mt. Ayanganna on outer toe slopes of mountain, 800–1100 m, N 5°25’, W 60°0’, 09.11.1992 (fr), B. Hoffman 3308 ( BRG, NY, U, US) GoogleMaps ; Membaru-Kurupung Trail, Pakaraima Mts. , 1000 m, 29.10- 04.11.1951 (veg), B. Maguire 32405 (B, NY, US, VEN [ paratypes]) ; Mt. Ayanganna, NE side of, upper Mazaruni River basin, 800–915 m, N 5°23’, W 59°57 ”, 14.08.1960 (fl.), S.S. Tillet 45000 (K, NY, US [ paratypes]) GoogleMaps ; Ibid 16.08.1960 (fl.), S.S. Tillet 45151 ( NY [ paratype]) ; 16.08.1960 (fl.), S.S. Tillet 45152 (G[ isotype], K[ isotype], NY [ isotype], US [ holotype]) . Potaro-Siparuni, Wokomung, base camp & vic., upper Potaro River region, 1070–1160 m, N 5°5’, W 59°50’, 30.06.1989 (fl.), B.M. Boom 8993 ( NY, US) GoogleMaps ; Mt. Wokomung , easternmost pinnacle of massif, 1524 m, N 5°05’34.4”, W 59°50’13.3”, 30.06.2003 (fl.), H.D. Clarke 10344 ( BRG, NY [2], US) GoogleMaps ; Mt. Wokomung , NE facing slopes above second of four escarpments, 1400 m, N 5°5’56”, W 59°50’16”, 01.07.2003 (fl.), H.D. Clarke 10389 ( NY [2], US) GoogleMaps ; Pakaraima Mts, Mt. Wokomung, Wusupubaru Creek , 2 km from juncture with Suruwabaru Creek , 975–1125 m, N 5°03’, W 59°53’, 13.02.1993 (fr), T.W. Henkel 1340 ( BRG, NY, US) GoogleMaps ; Pakaraima Mts, Mt. Wokomung. W slope on sub-plateau near head of Mo-toymabaru Creek , 1150–1200 m, N 5°04’, W 59°53’, 11.11.1993 (fr), T.W. Henkel 4286 ( BRG, CAS, FLAS, NY, U, US) GoogleMaps ; Ibid , 11.11.1993 (fl bud, fr), T.W. Henkel 4291 ( BRG, CAS, FLAS, INPA, NY, U, US) ; Pakaraima Mts-Mt. Wokomung , summit ridge of Ka-mie-wah pinnacle NE to S pinnacle, “Little Ayanganna”, 1550–1650, N 5°04’, W 59°52’, 17.11.1993 (fl.), T.W. Henkel 4436 ( BRG, CAS, FLAS, NY, US) GoogleMaps ; Pakaraima Mtns; upper Ireng watershed, Sukabi River , Kurdah Falls , lower E branch, 685 m, N 5°06’, W 59°97’, 20.10.1994 (fl.), P.A. Mutchnick 129 ( US) .

Conservation status: It is known from only six collections made in the last 12 years, only one of which is inside a national park. Moreover, four of the paratypes have been collected in areas that have been identified as future dam sites for hydroelectric power. The Extent of Occurrence ( EOO) is 474.3 km 2 and the Area of Occupancy ( AOO) is 20 km 2 with a total of 4 locations. Based on the low number of locations, the EOO and AOO and the fact that some of the areas are likely to be developed in the near future, it is recommended that Boyania kenwurdackii be considered Endangered under criteria B1ab(iii)+ B2ab(iii) ( IUCN, 2022).

Notes: Superficially, Boyania kenwurdackii closely resembles B. ayangannae , and indeed all the specimens assigned here to the new species had been initially determined as the latter. However, the two species differ by the number of petals, hypanthium indumentum, the size of the petals, and the size and morphology of the anther appendages (see diagnosis). Additionally, the ovary in B. kenwurdackii seems to range from ½ to fully inferior and it is 4-locular, while it is superior and 3-locular in B. ayangannae ; however, these characters are based on limited dissections for both species. Furthermore, B. kenwurdackii is easily distinguished from B. colombiana , the third species in the genus, by the leaf bases (obtuse to broadly acute vs. cordate), and the anthers dorsal connective appendages (present vs. absent). Although B. kenwurdackii and B. ayangannae both grow in central Guyana, and relatively close to each other, they have not been collected in the same locality. Boyania ayagannae has been mostly collected around Mount Ayanganna and Mount Wokomung at 800–1400 m, and once farther west along the Kurupung River at 350 m (Fig. 4). Boyania kenwurdackii has been mostly collected at 225–480 m on tributaries of the Potaro River farther north of Mount Ayanganna, and once (the type), at 1300 m in Kamakusa Mountain.

When Wurdack (1964) described Boyania he placed it in the expanded Sonerileae and noted that among neotropical members of the tribe it most closely resembled Diplarpea Triana or Monolena Triana ex Benth. & Hook.f. However , it is notable that he also remarked that it actually shared more characters with Old World Sonerileae . Diplarpea has now been synonymized under Triolena Naudin , and both Triolena and Monolena form the tribe Trioleneae , an exclusively neotropical group not part or sister to the Sonerileae as currently defined ( Bacci et al., 2020).

It should be noted that the collection cited as B. ayangannae in recent phylogenetic analyses ( Bacci et al., 2019; Wurdack & Michelangeli, 2019; Maurin et al., 2021; Penneys et al., 2022) is actually one of the paratypes of B. kenwurdackii . Moreover, when more than one species of Boyania have been included in phylogenetic studies the genus is not recovered as monophyletic, with both terminals close to the base of the tribe, although most of the branches in between these taxa have low or moderate support.