Virola amistadensis D.Santam., 2019

Santamaria-Aguilar, Daniel, Aguilar, Reinaldo & Lagomarsino, Laura P., 2019, A taxonomic synopsis of Virola (Myristicaceae) in Mesoamerica, including six new species, PhytoKeys 134, pp. 1-82 : 1

2. Virola amistadensis D.Santam. sp. nov. Figs 7B , 11

Diagnosis.

Similar to Virola calophylla in its abaxial leaf surface that is whitish and covered with stellate, sessile trichomes whose centre is reddish-clear to reddish and contrasting in colour with the hyaline branches and the lateral veins that are well-spaced. Virola amistadensis can be distinguished from V. calophylla by its shorter leaf blades [12.3-22.8 (-27) cm vs. (15-) 20-60 cm long] with a usually acute or sometimes attenuate base (vs. usually deeply cordate to truncate), shorter staminate inflorescence (3-7.5 cm vs. 12-30 cm long) and fruits with an obtuse base (vs. usually truncate).

Type.

Panama. Bocas del Toro: Vicinity of Fortuna Dam, below pass on Chiriquí Grande road, ca. 800 m elev., 27 Jun 1986 (♀ fl), G. McPherson 9717 (holotype: MO! [5565285, MO281258]; isotypes: INPA!* [144165], PMA!* [046113, PMA36179]).

Description.

Tree 4-13 m tall, no recorded DBH; bark and exudate not described in herbarium specimens. Twigs 0.18-0.42 cm thick, inconspicuous but densely strigulose, glabrescent, trichomes irregularly stellate to dendritic, ferruginous to whitish. Leaves: petiole 1.4-2.3 × 0.18-0.23 cm, slightly canaliculate, pubescent, trichomes stellate; leaf blades 12.3-22.8 (-27) × 4.4-9.5 (-12.5) cm, elliptic to widely elliptic; adaxial surface leaves pale to dark brown (sometimes shining) when dry, glabrous or occasionally with scattered stellate trichomes; abaxial surface usually whitish-greyish when dry, but can be very light to dark brown, densely but inconspicuously pubescent, trichomes stellate, sessile, ferruginous or sometimes with the central part of the trichome reddish, contrasting in colour with the hyaline branches to reddish-clear, with 4-8 branches, the branches ca. 0.02 mm, persistent (the surface with a dense layer of squamiform hyaline structures, especially obvious at high resolution); lateral veins 9-15 per side, 3-5 veins per 5 cm, (1.2-) 1.4-2.5 cm apart, the same colour as the adaxial surface, on adaxial surface flat to slightly elevated or slightly sunken, on abaxial surface raised, free or slightly anastomosing near the margin and without forming a very marked intramarginal vein; tertiary veins barely visible or indistinct on both surfaces; midvein adaxially raised, slightly sunken in a channel, abaxially raised, rounded, tomentose, adpressed pubescent to glabrate; base usually acute or sometimes attenuate, not revolute, flat; margin not revolute; apex acuminate. Staminate inflorescences 3-7.5 cm long, axillary, axes flattened, pubescent, with trichomes stellate, ferruginous; peduncle 1-2 × 0.09-0.16 cm; bracts not seen; terminal fascicles lax, with 2-11 flowers. Staminate flowers with the pedicel 0.7-1 mm long; receptacle sometimes ca. 1 mm wide; perianth 1.5-2.2 mm long, infundibuliform, brown when fresh (possibly due to indumentum), connate for ca. 0.8 mm of length, abaxial surface pubescent with brown trichomes, adaxial surface pubescent, especially on the lobes and margins; lobes 3, ca. 1.2 × 0.7 mm; stamens 3 (-6), the filament column 0.2-0.4 mm long, glabrous, straight, conspicuously thickened throughout its length, constricted at the apex; anthers 0.6-0.7 mm long; apiculus 0.1-0.15 mm long, apiculate, connate or slightly separated at the apex. Pistillate inflorescences 4.3-5 cm, similar to staminate inflorescences; peduncle 1.5-1.8 × 0.18-0.25 cm; bracts not seen; terminal fascicles of 4-10 flowers. Pistillate flowers in terminal fascicles of 4-10 flowers; with the pedicel 1.5-2 mm long; perianth 3.4-3.8 mm long, infundibuliform, brown-yellow when fresh, connate for 2.2-2.5 mm of length, abaxial surface pubescent, with brown trichomes, adaxial surface pubescent, especially on the lobes and sparsely pubescent basally; lobes 3, 1-1.4 × 1-1.2 mm; gynoecium 1.8-2 × 0.8-1.1 mm, densely pubescent, ovate, sessile; stigmatic lobes 0.4-0.5 mm, erect. Infructescence 2.7-6.3 cm long, with 1-5 fruits, peduncle 1-2.5 × 0.25-0.5 cm. Fruits 2.1-3.8 × 1.7-2 cm, ovoid to globose, shortly stipitate, densely tomentose, the trichomes irregularly stellate, ferruginous, persistent, the surface smooth to rugulate when dry, the line of dehiscence slightly carinate, the base obtuse, the apex acute to obtuse, brown to brown-yellow when fresh; pericarp 1-2 mm thick; pedicel 0.4-0.9 cm long; seed 1.6-2.2 × 1.4-1.6 cm, the testa when dry pale brown; aril described as red, pale brown or blackish when dry, membranaceous, dry in texture, thin, laciniate in narrow bands.

Distinctive characters.

Virola amistadensis is recognised by its elliptical to widely elliptical leaf blades with lateral veins that are well separated ( Fig. 8B ) and abaxially covered with stellate, sessile trichomes ( Fig. 3B ) and a dense layer of squamiform structures that are hyaline in colour; the small staminate flowers with a thickened filament column that is markedly constricted at the apex and shorter (0.2-0.4 mm long) than the anthers (0.6-0.7 mm), which are apiculate at the apex; and the ovoid to globose fruits ( Fig. 4B ) with relatively thin pericarp (1-2 mm thick) ( Figs 7B inset, 11D) that are covered by a dense, but inconspicuous layer of ferruginous trichomes. It is also distinctive for being a small tree (4-13 m tall) and its preference for premontane forests.

Etymology.

The specific epithet, amistadensis, refers to Parque Internacional La Amistad, a UNESCO World Heritage Site, shared between Costa Rica and Panama where the holotype and some of the paratypes of this species were collected.

Distribution.

Virola amistadensis is known from Costa Rica ( Limón) and Panama (Bocas del Toro and Veraguas; Fig. 9B ). It is found on the Caribbean slope at 650-1200 m elevation.

Preliminary conservation status.

Virola amistadensis is Endangered following IUCN criteria B1a and B2a. This species is known from 4 localities and has an EOO of 2,573 km2 and an AOO of only 28 km2. Only nine specimens were verified in this study. While it occurs in protected areas, its montane habitat is particularly prone to habitat disturbance.

Common names.

None recorded.

Phenology.

Flowering of V. amistadensis has been recorded in April, June and July and fruiting in January to March, May, June and December.

Field characters.

Plants are trees that are 4-13 m tall. Flowers have a yellow-brown perianth and brown fruits.

Discussion.

Herbarium specimens of this new species usually have been identified as Virola calophylla ( Figs 10A, B ) or V. macrocarpa ( Fig. 7C ), probably because its leaves are abaxially whitish and covered with stellate, sessile trichomes with a reddish-clear to reddish centre that contrasts in colour with the hyaline branches and lateral veins that are well-spaced. Differences between V. amistadensis and V. calophylla are enumerated in the diagnosis, while those separating it from V. macrocarpa are listed in Table 4 .

In Mesoamerica, Virola amistadensis is similar to V. allenii ( Figs 6 , 7A ) and V. otobifolia ( Figs 7D , 23 A–E ), two species from the lowland wet forest of Costa Rica and Panama. Their similarities include the characteristics of the leaf blades mentioned above. Their differences are summarised in Table 3 .

Notes.

Specimens from Veraguas Province (Panama), have smaller leaf blades and lateral veins that are more deeply sunken on the adaxial surface than the specimens from Limón and Bocas del Toro provinces.

Specimens examined.

Costa Rica. Limón: Parque Internacional La Amistad, subiendo por la fila entre la margen derecha del Río Uren y la Quebrada Crori, Croriña, 650 m elev., 17 Jul 1989 (♂ fl), A. Chacón 194 (CR, MO!). Panama. Bocas del Toro: Along pipeline road in area of Fortuna Dam, 900-950 m elev., 08 Mar 1986 (fr), G. McPherson 8703 (INPA!*, MO!, PMA!*); vicinity of Fortuna Dam, below pass on Chiriquí Grande road, 800 m elev., 27 Jun 1986 (fr), G. McPherson 9715 (INPA!*, MO!); along old pipeline road from continental divide, 900 m elev., 27 Dec 1986 (imm fr), G. McPherson & J. Aranda 10169 (INPA!*, MO!, PMA!*). Veraguas: Vicinity of Escuela de Agricultura Alto Piedra, near Santa Fé, 2800-3200 ft [850-975 m] elev., 03 Apr 1980 (♂ fl), T. Antonio 4011 (INPA!*, MO!); vicinity of Cerro Tute, 850-1000 m elev., 19 Mar 1987 (fr), G. McPherson 10687 (MO!); near Cerro Tute-Arizona, above Santa Fe and Alto de Piedra, 850-1100 m elev., 05 Feb 1988 (fr), G. McPherson 12047 (MO!); vicinity of Santa Fe on slopes of Cerro Tute-Arizona above school at Alto Piedra, 900-1100 m elev., 29 Jan 1989 (fr), G. McPherson 13669 (INPA!*, MO!); Cerro Tute, 1 km beyond Escuela Agrícola Alto Piedra above Santa Fe, 900-1200 m elev., 14 May 1981 (fr), K. Sytsma & L. Andersson 4653 (MO!).

Figures

Figure 3. Trichomes in Mesoamerican Virola A Virola allenii (R. Aguilar 2224, MO) B V. amistadensis (G. McPherson 8703, MO) C V. chrysocarpa (O. Valverde 970, MO) D V. elongata (G. McPherson 13674, MO) E V. fosteri (G. McPherson 20913, MO) F V. guatemalensis (R. Cedillo 3349, MO) G V. koschnyi (R. E. Gereau et al. 3455, MO) H V. laevigata (R. Aguilar 2004, MO) I V. megacarpa (J. A. Duke 15261, MO) J V. montana (E. Bello 855, MO) K V. multiflora (R. Rueda et al. 8196, MO; inset, J. C. Sandino 3302, MO) L V. nobilis from Barro Colorado (R. J. Schmalzel 320, MO) M V. otobifolia (G. de Nevers & H. Herrera 7056, MO) N V. sebifera (F. Almeda et al. 5553, MO) O V. nobilis from Osa Peninsula (R. Aguilar 11186, MO).

Figure 4. Fruits of Mesoameican Virola, organised in groups of morphologically similar species A V. allenii (P. H. Allen 6727, GH) B V. amistadensis (G. McPherson 9715, MO) C V. otobifolia (A. Gentry & S. Mori 14199, MO) D V. macrocarpa (A. E. Lawrance 675, MO) E V. chrysocarpa (B. Hammel et al. 16864, MO) F V. koschnyi (R. Robles 1587, MO) G V. guatemalensis (S. Sinaca 1542, MO) H V. montana (J. Utley & K. Utley 5054, MO) I V. fosteri (S. Mori & J. Kallunki 4891, MO) J V. multiflora (R. Rueda et a. l 9960, MO) K V. sebifera (T. B. Croat 5959, MO) L V. elongata (J. D. Dwyer & M. Correa 8420, MO) M V. laevigata (R. Aguilar 1585, MO) N V. nobilis from Barro Colorado (T. B. Croat 8090, MO) O V. nobilis from the Osa Peninsula (G. Herrera 4222, MO) P V. megacarpa (G. de Nevers 5184, MO). Scale bars: 1 cm.

Figure 6. Virola allenii A treetop B branching C lower trunk and buttress D branch with leaves, showing the adaxial surface E leaf blades on abaxial surface F exudate of the trunk G leaf blade surfaces, adaxial (above) and abaxial (below) H petiole and leaf base I mature fruit, inset left and arrow showing the galls on leaves and branches, respectively J fruits K fruit close-up. Photos by Reinaldo Aguilar.

Figure 7. Comparisons of Virola macrocarpa with similar species in Mesoamerica A V. allenii (P. H. Allen 5763, F; inset fruits, from P. H. Allen 6727, GH) B V. amistadensis (G. McPherson 9717, MO; inset fruits, from G. McPherson 9715, MO) C V. macrocarpa (A. E. Lawrance 675, MO) D V. otobifolia (J. P. Folsom 1440, MO). Image courtesy of Field Museum (A).

Figure 8. Pattern of the lateral veins in Mesoamerican Virola A Virola allenii (K. Thomsen 1284, NO) B V. amistadensis (G. McPherson 8703, MO) C V. chrysocarpa (B. Hammel et al. 16864, MO) D V. elongata (M. Correa & R. L. Dressler 1078, MO) E V. fosteri (G. de Nevers 7226, MO) F V. guatemalensis (G. Ibarra 957, MO) G V. koschnyi (J. Miller & J. C. Sandino 1110, MO) H V. laevigata (N. Zamora & T. D. Pennington 1583, MO) I V. megacarpa (G. de Nevers 5184, MO) J V. montana (E. Lepiz & J. F. Morales 284, MO) K V. multiflora (J. Manzanares 3561, MO) L V. nobilis from Barro Colorado (R. J. Schmalzel 320, MO) M V. otobifolia (G. de Nevers et al. 7530, MO) N V. sebifera (T. B. Croat 5959, MO) O V. nobilis from Osa Peninsula (R. Aguilar 11186, MO).

Figure 9. Geographic distribution of Virola allenii (A), V. amistadensis (B), V. chrysocarpa (C), V. elongata (D), V. fosteri (E) and V. guatemalensis (F).

Figure 10. Virola calophylla A branch with leaves, showing both sides B branch with inflorescences. Virola elongata C leafy branch with inflorescences, inset fruit D inflorescences. Virola guatemalensis E, F leaf blades showing adaxial (E) and abaxial (F) surface. G young twigs and petioles. Photos by Robin Foster (A, B), from https: // plantidtools. fieldmuseum. org / en / nlp; Steven Paton (C, D), Rolando Perez (C inset), from https: // stricollections. org / portal / index. php and Angela Rojas (E-G).

Figure 11. Virola amistadensis A leaf with staminate inflorescences B leaf C fruits D pericarp E seed. Drawn by Pedro Juarez, based on G. McPherson 9717 (A) and G. McPherson 9715 (B-E).

Figure 23. Virola otobifolia A branch with leaf blades showing both surfaces and inflorescences B leaf blade, venation and base on abaxial surface C infructescence D fruits E detail of fruit, showing an aril of an immature fruit. Virola surinamensis. F Branch with inflorescences G, H leaf blade on adaxial (G) and abaxial surface (H). I Infructescence J detail of fruits, including a longitudinal section of an immature fruit. Photos by Rolando Perez (A, B from https: // stricollections. org / portal / index. php); Jerry Harrison (C), Alwyn H. Gentry (D, E from http: // www. tropicos. org) and John P. Janovec (F-J from http: // atrium. andesamazon. org /).