Myrcianthes roncesvallensis
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https://doi.org/ 10.11646/phytotaxa.284.3.5 |
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persistent identifier |
https://treatment.plazi.org/id/AB27882E-FF9A-FFD7-FF29-F8ADFDAFBC3D |
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Felipe |
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scientific name |
Myrcianthes roncesvallensis |
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Myrcianthes roncesvallensis View in CoL C. Parra-O. & Bohórquez-Osorio, sp. nov. ( Figures 1 View FIGURE 1 , 2 View FIGURE 2 )
Type: — COLOMBIA. Tolima: Roncesvalles, “vereda Yerbahuena, páramo Yerbahuena, Reserva Natural de las aves Loros Andinos (Proaves)”, 3221 m, 04°05’04.4’’N, 75°42’19.8’’W, 12 September 2015 (buds, fl., fr.), Carlos Parra-O. & A. F. Bohórquez 853 (holotype COL!, isotypes COL!, CUVC!, FAUC!, FMB!, HUA!, JAUM!, TOLI!).
This species is most similar to Myrcianthes rhopaloides ( Kunth 1823: 137) McVaugh (1958: 771) , from which it is distinguished by having a closed calyx (versus open calyx in M. rhopaloides ), moderately pubescent inflorescence and flower buds (versus glabrous inflorescence and flower buds in M. rhopaloides ), 75–100 stamens (versus 150–175 in M. rhopaloides ), and anthers 0.4 mm long (versus anthers 1 mm long in M. rhopaloides ).
Tree, 2–15 m tall; bark light brown or grey peeling in irregular plates; hairs when present 0.4–4 mm, simple, light reddish drying brownish yellow; young branches quadrangular in cross-section, vinaceous, glabrous; old branches subcompressed to terete, grey, glabrous; branches with young buds densely puberulous, light reddish. Leaf blades wide elliptic, elliptic or suborbicular, occasionally almost orbicular, (1.5) 2.2–6 (7.5) × (1.2) 1.8–4.5 (6.7) cm, coriaceous, discolorous, the upper surface glabrescent with hairs becoming hyaline in older leaves, with impressed blackish to dark yellow glandular dots, the lower surface glabrescent or sparsely to moderately puberulous, with raised dark vinaceous glands; apex rounded, sometimes obtuse or retuse, frequently mucronate; base obtuse, sometimes almost rounded; margin entire to slightly revolute; midvein sulcate and glabrous to slightly puberulous above, convex and glabrous to glabrescent below; lateral veins 7–10 pairs, slightly sulcate to sulcate and slightly to moderately puberulous above, convex and glabrous to slightly puberulous below; petiole 2.3–4.4 mm long, vinaceous or blackish, slightly rugose, glabrous to moderately puberulous, canaliculate. Inflorescence axillary, simple or sometimes compound dichasium, (1.6) 2–4.6 (5.6) cm long, usually solitary or sometimes paired and opposite, with 3–7 flowers, the axes compressed, glabrous to densely puberulous, light reddish when young, vinaceous to dark brown when mature; peduncles (10) 13– 37 (41) × 1.7–2.1 mm; bracts lanceolate, 1.3–3.2 × 0.5–0.6 mm, glabrescent to moderately pubescent, truncate in the base, persistent; bracteoles 2, opposite at base of hypanthium, lanceolate or ovate, 1.4–1.8 × 0.3–0.7 mm, glabrescent to moderately pubescent, persistent after anthesis; flower buds globose, green to dark brown, sometimes with violet spots at the apex, 4–7.5 mm long, 2.7–4.4 mm in diameter, moderately pubescent, sessile or a subcompressed pedicel 1.1–1.5 (2) × 0.5–0.8 mm, moderately puberulous; calyx closed, in anthesis detaching as a regular or irregular calyptra, or tearing in 2–4 more or less regular lobes, calyptra (when present) discoid, 4.9–6.5 mm in diameter, pubescent, prominently apiculate, the apiculum 0.8–1.5 mm; petals 4, white, sometimes with pink or red strips or spots, broadly to very broadly ovate, 5.5–6.7 × 7–7.6 mm, glabrous or sometimes with tiny sparse hairs at margin and apex, apex obtuse to rounded, base truncate; hypanthium 2.4–4.2 mm in diameter, not prolonged above the ovary, moderately to densely pubescent outside, glabrous inside, sometimes with irregular tissue remnants of the dehiscence of the calyx; disk semiquadrangular or almost quadrangular, white to whitish, 4.2–5.6 mm, slightly pubescent; style white, becoming pink to dark red with age, generally straight, sometimes geniculate, 8.6–11 mm long, glabrous; stamens 75–100; filaments white, 5.2–9.5 mm, anthers ellipsoid, cream, 0.4 mm long, without glands; ovary 1–1.7 mm in diameter, 2(–3)-locular, 20–25 ovules per locule. Fruits globose, dark violet when mature, 1.3–1.7 cm in diameter, glabrous; seeds 2–4, slightly reniform, 13 × 7.6 mm, seed coat papyraceous, brownish to light brownish, smooth; embryo with two separate plano-convex cotyledons, with minute light brownish glands.
Etymology: —The specific epithet of the new species refers to the municipality of Roncesvalles, which is located in the west of the department of Tolima in Colombia.
Phenology: —Collected with buds and flowers in January and September; collected with fruits in September.
Distribution, habitat and ecology: — Myrcianthes roncesvallensis seems to be endemic to Colombia and is only known from Andean forest in Roncesvalles between 3127–3286 m elev. This species is growing together with species of Baccharis Linnaeus ( Asteraceae ; Linnaeus 1753b: 860), Ilex Linnaeus ( Aquifoliaceae ; Linnaeus 1753a: 125), Vaccinium Linnaeus ( Ericaceae ; Linnaeus 1753a: 349), Viburnum Linnaeus ( Adoxaceae ; Linnaeus 1753a: 267), Hesperomeles Lindley ( Rosaceae ; Lindley 1837: tabula 1956) and Rubus Linnaeus ( Rosaceae ; Linnaeus 1753a: 492), in secondary forests or in open areas associated with human disturbance.
Fruits of M. roncesvallensis are eaten by certain species of birds, such as the ‘loro coroniazul’ ( Hapalopsittaca fuertesi ) and the ‘mirla ojiamarilla’ ( Turdus fuscater ) (G. Cardona & A. López, personal communication). In fact, M. roncesvallensis is being planted in some areas of the Natural birds Reserve ‘Loros Andinos’, in order to provide food for Hapalopsittaca fuertesi ; this parrot is endemic to the area and is classified as a Critically Endangered species (BirdLife International 2016).
Common name: — “guayabo ” (Parra-O. & Bohórquez 853).
Conservation status: —Because this species is only known from one location, and no additional collections have been found, the conservation status of M. roncesvallensis can only be assessed as Data Deficient, or DD, following IUCN Red List criteria ( IUCN 2012).
Molecular affinities:—Sequences of all three selected barcode markers were obtained. For ITS, a 647 base pairs length fragment was recovered; a BLAST search of it found the top match (KJ187656.1) to be a specimen of Myrcianthes pungens ( Berg 1857 -1859: 224) Legrand (1968: 52), and the following two matches were a specimen (AM234100.1) of Myrcianthes pseudomato ( Legrand 1944: 477) McVaugh (1963: 493) and an additional accession (AM234099.1) of M. pungens . The three top matches had an identity value of 98% compared to the sequence of M. roncesvallensis . For mat K, a 783 bp length fragment was recovered and a BLAST search of it found the top match (KR867678.1) to be a specimen of Eugenia uniflora Linnaeus (1753a: 470) with an identity value of 99%; for E. uniflora the complete plastid genome has been sequenced. The next top matches were four mat K sequences (DQ088554.1, AY521545.1, KM065289.1, KM065298.1) of specimens of Pimenta Lindley (1821: 19) , also with identity values of 99%. In GenBank there are only two mat K sequences of Myrcianthes [i.e., M. fragrans ( Swartz 1788: 79) McVaugh (1963: 485) ; KJ772955.1) and M. cisplatensis ( Cambessèdes 1832: 342) Berg (1856: 315) ; JN661013.1)], but neither of them were found as matches in the BLAST search. Differences between mat K sequences of M. cisplantensis , M. fragrans , and M. roncesvallensis are explained by the use of different primer pairs to obtain the sequences, where each primer combination recovers different portions of the mat K region and not the entire region. Between M. fragrans and M. roncensvallensis mat K sequences there is a difference of 129 bp, where the M. fragrans sequence is shorter (654 bp) than that of M. roncesvallensis . Although M. roncesvallensis and M. cisplatensis (757 bp) are quite similar in length, they only match by 276 bp; the primers used for obtaining the sequence of M. cisplatensis recover a portion of the mat K gene and the flanking trn K intron (Murillo-A. et al. 2012), whereas the 3F_KIM and 1R_KIM primers falls into the mat K gene.
For rbc L, a 551 bp length fragment was recovered; a BLAST search of it found the top match (KF981267.1) to be a specimen of Pimenta pseudocaryophyllus ( Gomes 1812: 92) Landrum (1984a: 242) , and the second match was a specimen of Myrcianthes fragrans (U26328.2), both with an identity value of 99%.
Discussion and affinities: — Myrcianthes roncesvallensis is the first species of the genus found to have a closed calyx; all the other species of Myrcianthes described to date have flowers with an open calyx that has four or five well defined calyx lobes. In this species, when anthesis occurs, the closed calyx detaches as a unit (i.e., regular calyptra; equivalent to the ‘closed calyptra’ or ‘well defined calyptra’ of Lucas et al. 2011) in some of the flowers ( Figure 2A View FIGURE 2 ), whereas in other flowers the calyx tears in two, three or four more or less regular lobes ( Figure 2B View FIGURE 2 ); sometimes both types of anthesis occur in flowers of the same inflorescence ( Figures 1B View FIGURE 1 , 2C View FIGURE 2 ). Interestingly in the flowers where the calyx starts to open as a unit, the calyptra does not always remain as a unit; sometimes it breaks up into irregular portions, leaving an irregular calyptra and some tissue remnants that persist attached to the hypanthium, resembling calyx lobes ( Figure 2D View FIGURE 2 ); in this case it seems to be that the calyptra is not detached from the rim of the hypanthium at anthesis, but somewhere above it. The calyptra and/or the tissue remnants sometimes remain attached to the fruits during their development, growing bigger in size. In Neotropical Myrtaceae the remnants of the calyx in the fruit are useful for generic identification, along with other characters, because most of the times it allows the observer to infer the type of flowering calyx of the specimen (Parra-O. 2014). The remnants of the calyx in the fruit of M. roncesvallensis are not always useful for identifying the type of calyx, because they could be derived from regular or irregular calyptras (that easily fall), calyx lobes, or tissue remnants that were attached to the hypanthium when the breaking up of the irregular calyptra occurred ( Figures 2E, 2F View FIGURE 2 ).
There have been reports of species having a closed calyx appearing in at least one other genus (i.e., Myrceugenia O. Berg, 1855 –1856: 5) that was traditionally accepted as having an exclusively open calyx ( Landrum 1984b). The presence of a closed calyx in the flower has evolved independently in different genera of Myrtaceae , and genera such as Campomanesia Ruiz & Pavón (1794: 72) and Psidium Linnaeus (1753a: 470) have a variable degree of calyx fusion (from closed calyx to open calyx) among their species ( Landrum 1984b). McVaugh (1968) was reluctant to use calyx characters as the main feature for delimiting genera in American Myrtaceae .
Myrcianthes roncesvallensis is apparently related to M. rhopaloides , and both species are vegetatively similar; they can be differentiated by the floral characters mentioned in the diagnosis. Although both species show wide variation of shape of the leaf blade, in M. roncesvallensis it is common to find suborbicular to occasionally almost orbicular leaf blades in adult as well as young branches; in M. rhopaloides such leaf blade shapes are more common to be found in sprouts or, sometimes, in some of the old leaves.
Because the three DNA barcode markers used here were useful to confirm the proper genus where this new species had to be described, we recommend that this approach could be used in situations where generic placement of a Myrtaceae species is unclear.
Paratypes: — COLOMBIA. Tolima: Roncesvalles , “vereda Yerbahuena, Reserva Natural de la aves Loros Andinos (Proaves), ‘borde del río Cucuana’”, 3127 m, 21 January 2014 (buds, fl.), A. F. Bohórquez-O. 862 (COL!) ; Roncesvalles , “vereda Yerbahuena, páramo Yerbahuena, Reserva Natural de las aves Loros Andinos (Proaves)”, 3286 m, 04°05’14.8’’N, 75°42’24.1’’W, 11 September 2015 (buds, fl.), C. Parra-O. & A. F. Bohórquez 849 (COL!, CUVC!, FAUC!, FMB!, HUA!, TOLI!) GoogleMaps ; ibidem, 11 September 2015, C. Parra-O. & A. F. Bohórquez 850 (COL!); ibidem, 11 September 2015, C. Parra-O. & A. F. Bohórquez 851 (COL!, FAUC!); Roncesvalles , “vereda Yerbahuena, páramo Yerbahuena, Reserva Natural de las aves Loros Andinos (Proaves)”, 3221 m, 04°05’04.4’’N, 75°42’19.8’’W, 12 September 2015 (buds, fl., fr.), C. Parra-O. & A. F. Bohórquez 852 (COL!, FAUC!, FMB!, HUA!) GoogleMaps ; ibidem, 3272 m, 04°04’57’’N, 75°42’18.2’’W, 12 September 2015 (buds, fl.), C. Parra-O. & A. F. Bohórquez 854 (COL!, FAUC!); Roncesvalles , “vereda Yerbahuena, finca La Riviera”, 3280 m, 04°05’04.2’’N, 75°42’09.6’’W, 12 September 2015 (fr.), C. Parra-O. & A. F. Bohórquez 856 (COL!, HUA!) GoogleMaps ; ibidem, 12 September 2015 (buds, fl.), C. Parra-O. & A. F. Bohórquez 857 (COL!, FAUC!, TOLI!).
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