Amanoa condorensis J.L.Clark & D.A.Neill, 2023

Clark, John L. & Neill, David A., 2023, Amanoa condorensis (Phyllanthaceae), a new shrubby species from the Cordillera del Condor in southern Ecuador, PhytoKeys 227, pp. 89-97 : 89

Amanoa condorensis J.L.Clark & D.A.Neill sp. nov.

Figs 1 , 2

Diagnosis.

Amongst the Neotropical species of Amanoa , A. condorensis shares with A. almerindae Leal. and A. caribaea Krug & Urb. the presence of an androphore, formed from the fusion of the basal filaments. Differs from Amanoa almerindae by the densely pubescent and more widely-spaced flowers along an inflorescence axis 5.5-11 cm long in A. almerindae vs. nearly glabrous inflorescence axis to 4.5 cm long in A. condorensis. Differs from A. caribaea by the presence of inflorescences in an elongate erect raceme appearing congested throughout vs. inflorescences in elongate erect spikes with evenly-spaced fascicles (i.e. not congested throughout) in A. caribaea .

Type.

Ecuador. Zamora-Chinchipe: Nangaritza Cantón, Cordillera del Cóndor, trail west of Cabanas Yankuam in conservation area that is owned/operated by ATASMO ( Asociacion de Trabajadores Autonomos San Miguel de las Orquídeas). Forested tepui (sandstone plateau). Summit ridge and sandstone cliff face. Low scrub and elfin forest, canopy mostly 2-3 m tall, occasional emergent trees to 5 m, 4°15'47.5"S, 78°41'28.1"W, 1840 m elev., 10 Mar 2017, J.L. Clark, J.A. Mayr & D.A. Neill 15257 (holotype: ECUAMZ [08582]; isotypes: SEL [120063], US) .

Description.

Tree, 4 m tall. Leaves 1.2-2.5 × 3-4.5 cm, oblong to ovate, coriaceous, glabrous, secondary venation suppressed adaxially when live and becoming prominent when dry, abaxial secondary venation prominent when live and dry, sparsely pubescent on abaxial and adaxial surface, blade flat, base narrowly cuneate to acute, apex acute; petiole 4-8 mm long, slender, black, rugose, sparsely pilose, sometimes appearing sessile from the intrapetiolar stipule; stipules conspicuous, to 0.5 mm long, triangular and glabrous. Inflorescence terminal or lateral, to 4.5 cm long, in congested erect elongate raceme-like inflorescences derived from reduced cymules, the primary inflorescence branch dark black, nearly glabrous to sparsely pubescent with short curved trichomes of 3-5 cells, each flower or pair of flowers subtended by a prominent brown triangular bracteole, 2-3 mm long and glabrous. Staminate flowers actinomorphic, 5-merous, 6.5-7.5 mm in diam. during anthesis, on short pedicels and appearing sessile; sepals 3.0-3.5 × 1.5-2.0 mm, broadly ovate, glabrous, white; petals ca. 1 × 1.5 mm, reniform, margins entire, glabrous; androecium surrounded by a prominent hypogynous extra-staminal disc, stamens fused at base, forming a short androphore, filaments 1.5-2 mm long, anthers 1-2 mm long, dehiscing longitudinally; pistillode ca. 2.5 mm long with trilobed apex, mature gynoecium or pistillate flowers not observed. Fruits not observed.

Phenology.

Mature male flowers were observed in March.

Etymology.

The specific epithet is derived from the Cordillera del Cóndor mountain range in southern Ecuador where this species is presumably endemic.

Distribution and associated vegetation.

Amanoa condorensis is only known from the type collection. It is presumed endemic to the Cordillera del Condór from where it was collected during a collaborative field course in 2017 with the Lawrenceville School (Lawrenceville, NJ, USA) and the Universidad Estatal Amazónica (Puyo, Ecuador). The type locality is situated at the summit ridge of a sloping plateau (1840 m elevation) west of the upper Nangaritza River, with nutrient-poor soil derived from the Cretaceous Hollín sandstone formation. The vegetation at the site is a low, dense scrub, dominated by shrubs and low trees 3-5 m high. These environments in the Cordillera del Cóndor and other mountain ranges east of the main Andean chain in Ecuador and Peru have been referred to as "Andean tepuis" in recognition of the similarity in vegetation and some phytogeographic connections with the low-nutrient sandstone tepuis of the Guiana Shield Region ( Neill et al. 2014; Neill 2018). Associated plants at the collection site include the local endemic Blakea nangaritzana D. Fernández, C.Ulloa & Penneys ( Melastomataceae ) as well as other species that are common in Andean tepui elfin forest vegetation at 1500-2000 m elevation, including Godoya obovata Ruiz & Pav. ( Ochnaceae ), Ternstroemia circumscissilis Kobuski ( Pentaphylacaceae ), Macrocarpaea innarrabilis J.R.Grant ( Gentianaceae ), M. ericii J.R.Grant ( Gentianaceae ), Cybianthus magnus (Mez) Pipoly ( Primulaceae ), Podocarpus tepuiensis J.Buchholz & N.E. Gray ( Podocarpaceae ), Ladenbergia franciscana C.M.Taylor ( Rubiaceae ), Pterozonium brevifrons (A.C.Sm.) Lellinger ( Pteridaceae ) and Everardia montana Ridl. ( Cyperaceae ).

Preliminary assessment of conservation status.

The type locality is located within a community-based protected forest managed by the Asociación de Trabajadores Autónomos San Miguel de las Orquídeas (ATASMO) on the remote summit ridge of a sloping Andean tepui at 1840 m elevation, accessible via a 6 km trail from the Cabañas Yankuam (= Yankuam Lodge) located at 890 m elevation on the banks of the Río Nangaritza. Yankuam is a family-owned lodge specializing in bird tours and ecotourism. The Río Nangaritza is at risk from ongoing illegal mining. Many of the areas visited in 2017 (especially along the Río Nangaritza) have been invaded by illegal mining operations. The forest that corresponds to the only known population of Amanoa condorensis is protected by the local community, which was granted this jurisdiction by the Ministry of Environment of Ecuador. Between 2017 and 2019 (three years), annual field courses were run with Cabañas Yankuam and the local community to different sandstone tepuis. Amanoa condorensis was only observed once throughout three consecutive years of field courses. Following the IUCN (2012) and guidelines of the IUCN Standards and Petitions Committee (2022), Amanoa condorensis is categorized as Critically Endangered (CR), based on the following criteria: B1, B2 ab (all criteria), area of occupancy (AOO) is calculated at 4 km2 (criterion B2 <10 km2). The species is known only from the type collection; it is hoped that this publication will stimulate more intensive search for additional material near the type locality and on other Andean tepuis in the region, including specimens with pistillate flowers.

Comments.

Most species of Amanoa are canopy to sub-canopy trees in the lowland tropics. The only other species that is known to occur above 1000 m is Amanoa steyermarkii Jabl. in the riparian and tepui forests of the Venezuelan Guayana Region at 1500-2100 m elevation ( Hayden 1999). Amanoa condorensis was collected above 1800 m. Amanoa condorensis differs from A. steyermarkii by its sessile staminate flowers (vs. pedicellate flowers in A. steyermarkii ) and its congested inflorescence (vs. the relatively lax inflorescence in A. steyermarkii ). It also differs in its shrubby habit (vs. trees in A. steyermarkii ).

Amanoa condorensis differs from most other congeners in its relatively small height of 4 m. Most other Amanoa species are understory to emergent canopy trees above 12 m tall (e.g. A. guianensis Aubl. reaches 35 m tall). It is also distinguished by the relatively small, thick and sclerophyllous leaves, characters that are shared by many plants in different genera that occur in the dense scrub vegetation of the Andean tepuis ( Neill et al. 2014) and that may be an adaptation to the nutrient-poor sandy soils of these habitats. The two other Amanoa species that are recorded as shrubs or small trees include A. cupatensis Huber and A. almerindae ; both species are endemic to the white-sand areas of the Rio Orinoco-Casiquiare lowlands and the adjacent Río Negro lowlands in Amazonas State of Venezuela and Amazonas State of Brazil. Amanoa cupatensis is a low shrub less than 2 m tall. Amanoa condorensis differs from A. cupatensis by the presence of an acute leaf apex (vs. rounded to emarginate leaf apex in A. cupatensis ).

Amanoa condorensis shares the following characters with other congeners: an extra-staminal disc (Fig. 1 ), intrapetiolar stipules, and a showy perianth represented by conspicuous sepals and inconspicuous petals (Fig. 1 ). The petals are only apparent with a 10 × hand lens or higher magnification (Fig. 1A ). The intrapetiolar stipules in A. condorensis are conspicuous on herbarium specimens and in the field.

Amanoa condorensis has an androphore, a structure formed by the basal fusion of the filaments (Fig. 1C ), a character that is only reported for two additional species: A. almerindae and A. caribaea Krug & Urb. The inflorescence of A. caribaea is an elongate spike-like inflorescence with broadly spaced fascicles of numerous flowers. In contrast, A. condorensis has congested inflorescences, but never more than two flowers per bracteole. Amanoa caribaea is endemic to the Caribbean (Dominica and Guadeloupe), where it is reported as a common co-dominant important timber tree in native forests of Dominica ( Nicolson 1991).

Amanoa pubescens was previously considered a synonym of A. almerindae , but was separated and resurrected by Secco et al. (2014), based on the presence of an androphore in A. pubescens and its absence in A. almerindae . However, Secco and Rosário (2016) re-examined the type material of both taxa and determined that A. almerindae does possess an androphore that is evident in open staminate flowers, but not in bud. As a result, Secco and Rosário (2016), once again, reduced A. pubescens to synonymy with A. almerindae . Amanoa almerindae differs from A. condorensis in its thinner, larger more widely-spaced leaves, and more elongate inflorescences with more broadly spaced fascicles (vs. thick, sclerophylous, smaller leaves and short, congested inflorescence in A. condorensis ).

Hayden (1990) reported that most flowers in Amanoa are protandrous and species can be either monoecious or dioecious. Only two Neotropical species are known to be dioecious: A. glaucophylla Müll.Arg of Amazonian and coastal Brazil, as well as Amazonian Colombia and Venezuela and A. anomala Little, endemic to the Pacific coast of Ecuador. The remaining species are presumed to be monoecious, but this has not been confirmed for most species. The flowers featured here (Fig. 1 ) have mature androecia with vestigial gynoecia. Therefore, if the species is monoecious, we expect the pistillate flowers would appear at a later stage. If dioecious, then separate staminate and pistillate individuals would be expected.

Figures

Figure 1. Amanoa condorensis J. L. Clark & D. A. Neill A-C mature staminate flower featuring prominent sepals, reduced petals, extra-staminal disc and androphore D shoot featuring two-ranked foliage and congested inflorescences. (A-D J. L. Clark, D. A. Neill & J. Mayr 15257). Photos by John L. Clark.

Figure 2. Holotype (ECUAMZ) of Amanoa condorensis J. L. Clark & D. A. Neill.