Passovia bracteata Caires & Dettke, 2021

Caires, Claudenir Simões & Dettke, Greta Aline, 2021, Passovia bracteata, a new species of Loranthaceae endemic to the Brazilian Amazon, Phytotaxa 490 (1), pp. 114-117 : 116

Passovia bracteata Caires & Dettke , sp. nov. ( Fig. 1A‒E ).

Type: — BRAZIL. Amazonas: Manaus, Residência do Dr. Costa Leite , terra firme, 26 December 1955, R. Valle s.n. ♀ (holotype MG- 21651!; isotypes INPA-1899! and UB-153241!) .

Diagnosis: — Passovia bracteata differs from all its congeners by the foliaceous bracts subtending the triads and/or flowers, 2‒4 × 0.2‒0.7 cm, ensiform, base attenuated, and apex acute.

Description: —Aerial branch hemiparasitic plants, dioecious. Epicortical roots not seen. Stems terete, percurrent; branches pendulous; internodes 4.4‒6(‒8) × 0.3‒0.4 cm, terete proximally, somewhat flattened distally, with two rigid wings (ancipitate). Leaves decussate to subalternate, petiolate; petiole 10‒12 mm long; blades 7.5‒8.5 × 4‒4.9 cm, chartaceous in sicco, ovate to lanceolate, base obtuse, apex acute to cuspidate; venation pinnate, midrib reaching the apex, conspicuous on both sides. Racemes simple, pedunculate, 1 per leaf axil, (2.5‒) 5.5‒6 cm long, sometimes the basal portion of the inflorescence (the first node) branched; axis angular (ancipitate), basal internode 1.8‒3 × ca. 0.1 cm, distal internodes 0.7‒0.9 cm long. Triads pedundulates, decussate to subalternate, 3‒4(‒10) pairs, rarely reduced to monads at the apex; peduncle 3‒5 mm long. Bracts subtending triads, 2‒4 × 0.2‒0.7 cm, foliaceous, ensiform, base attenuate, apex acute; bracteoles 2‒4 mm long, scale-like. Staminate flowers not seen. Pistillate flowers hexamerous, sessile, 4‒5 × 1.5 mm; calyculus smooth, petals more or less isomorphic, yellow, ca. 2 mm long; staminodes not seen; ovary ca. 2 mm long; style ca. 2 mm long, massive, stigma capitate, papillate. Fruit ca. 8 × 4 mm, ellipsoid, red when mature, embryo linear 5 × 1 mm.

Etymology: —The epithet bracteata refers to the long foliaceous bracts subtending the triads and/or flowers.

Distribution, habitat, phenology, and conservation assessment: — Passovia bracteata is known only from the type specimen, collected in 1955 in an urban area parasitizing a mango tree. The region of the municipality of Manaus is located in a patch of “terra firme” of Central Amazon, and we were unable to locate any other herbarium specimens during our studies for the Flora do Brasil 2020 project. Flowers and mature fruits were collected in December. This new taxon is assessed as Data Deficient (DD), according to the IUCN criteria ( IUCN, 2012), due to being currently represented by a single collection.

Taxonomic notes: — Passovia bracteata is easily distinguished by the presence of long bracts (2‒4 cm long) subtending the triads and/or flowers. The morphology of its branches, the leaves, and triad arrangement resemble P. pedunculata ( Jacquin 1760: 18) Kuijt (2014: 177) . However, bracts and bracteoles in the latter are scale-like. Yet among Passovia species , Passovia beckii Kuijt (2011: 182) has scale-like non-foliaceous bracts, with maximum 2‒2.5 mm long. This species is also distinct from P. bracteata due to the following characteristics: epicortical roots present along the branches (absent in P. bracteata ); quadrangular young stems (vs. young stems teretes) and terminal compound inflorescences (vs. axillary racemes). Thus, P. bracteata represents the first and only species in the genus with foliaceous bracts. In other small-flowered genera of Neotropical Loranthaceae , the presence of long bracts has been observed exclusively in Struthanthus longibracteatus Kuijt (2003: 78) , where they can be caducous, 2‒3 mm long, and subtending the triads ( Kuijt 2003). In P. bracteata , bracts are not only associated with the triads and/or flowers, but they can also appear at the base of the peduncle or in the proximal node of the raceme, subtending the triad’s peduncle. Passovia bracteata can also be easily distinguished from S. longibracteatus by their contrasting leaf morphologies (i.e., elliptical leaves with obtuse apex in S. longibracteatus vs. ovate leaves with acute or cuspidate apex in P. bracteata ).

In the impossibility of analyzing the staminate flowers, we prefer to position this new species in Passovia , as we consider its morphological aspect more similar. In addition, subtle details present in the styles of the pistilate flowers, show scars of the staminodes, demonstrating that they had different heights causing lateral protuberances, which, in our opinion, would cause the same depressions observed in Passovia . The depressions present in the Passovia filaments are caused by the anthers of the smaller stamens. However, examination of staminate flowers is necessary to fully confirm our proposed of placement on Passovia .

Figures

FIGURE 1. Passovia bracteata Caires & Dettke. A. Flowering branch, B. Inflorescence with flower buds and bracts, C. Close-up of the inflorescences, D. Detail of a foliaceous bract subtending a flowers triad, E. Infructescence with the first node branched and fruits. A‒D. From the holotype (MG-21651), E. From the isotype (UB-153241). Drawn by C.S. Caires.