Virola bombuscaroensis D. Santam., 2022

Santamaria-Aguilar, Daniel & Lagomarsino, Laura P., 2022, New Species of Virola (Myristicaceae) from South America, PhytoKeys 197, pp. 81-148 : 81

3. Virola bombuscaroensis D. Santam. sp. nov.

Type.

Ecuador. Zamora-Chinchipe: PN [Parque Nacional] Podocarpus, Bombuscaro entrance, 04°07'S, 078°58'W, 1350 m, 25 Jan 2011 (fr), J. Homeier 4507 (holotype: MO! [accession 6863380, barcode MO-3053475]; isotypes: n.v.). Fig. 8

Diagnosis.

Virola bombuscaroensis differs morphologically from all other species by the combinations of abaxial leaf surface covered by stellate, sessile trichomes, perianth of staminate flowers densely pubescent on both faces, and the column of filaments that has scattered trichomes at the base.

Tree 6-15 m tall, diameter, inner bark and exudate not described. Twigs 0.43-0.62 cm thick, terete to laterally flattened, tomentose to tomentulose, trichomes dendritic, sessile, ferruginous to whitish, the bark sometimes with small lenticels. Leaves young terminal bud 2.5-2.9 × 0.4-0.48 cm, with conspicuous veins; petiole 1.5-2.2 × 0.33-0.5 cm, canaliculate, sometimes very short alate, tomentose, the trichomes dendriform; leaf blades 23.3-30 × 7.1-10.3 cm, ovate; adaxial surface of mature leaves dries brown to olivaceous, glabrous or with very few and scattered trichomes (densely pubescent on new leaves), the surface smooth, sometimes shiny; abaxial surface when drying brown or whitish-grayish, densely pubescent, but inconspicuous to the naked eye, trichomes stellate or sometimes dendriform trichomes along the main veins, the stellate trichomes 0.1-0.2 mm diameter, sessile, the central part of the trichome (usually) reddish and contrasting in color with the hyaline to reddish branches, or the branches the same color as the central part, the dendriform trichomes ca. 0.4 mm long, ferruginous, persistent; lateral veins (13-) 18-23 per side, (3-) 4-5 veins per 5 cm, spaced (0.9-) 1.4-1.8 cm apart, on adaxial surface flat or elevated, the same color as the adaxial leaf surface or a little darker, on abaxial surface raised or flat, rounded or laterally compressed, tomentose to glabrescent, arcuate-ascending, slightly anastomosing near the margin and without forming a very marked intramarginal vein; tertiary veins slightly visible on both sides, more prominent on adaxial side; midvein adaxially slightly elevated, abaxially raised, usually rounded, tomentose; base cordate, not revolute, flat; margin flat to slightly revolute; apex acuminate. Staminate inflorescences ca. 5.4 cm long, axes flattened, tomentose, the trichomes dendritic, ca. 0.3-0.4 mm long, ferruginous; peduncle ca. 2 × 0.27 cm; main axes with 5 ramifications, the first pair opposite, the others alternate; bracts not seen. Staminate flowers (in bud) in dense terminal fascicles of 13-15+ flowers, on a receptacle 2-2.7 mm wide; perianth 2.8-3.4 mm long, obovoid, fleshy, brown when fresh, connation not seen (young flowers), external surface densely pubescent with ferruginous and dendritic trichomes, internal surface densely pubescent; lobes 3, not measured (young flowers), ca. 0.2 mm thick, without resinous punctuations when rehydrated; stamens 3, the filament column ca. 1.4 mm long, ca. 0.4 mm wide, slightly pubescent at the base, straight to slightly thickened at the base, not constricted at the apex; anthers ca. 0.9 mm long, ca. 0.4 mm wide; apiculus ca. 0.1 mm long, apiculate, separate. Pistillate inflorescences and pistillate flowers not seen. Infructescence 3-3.5 cm long, with 2-6 fruits, peduncle 1.8-3 × 0.43-0.5 cm. Fruits 2.4 × 1.8-1.9 cm, brown when fresh (probably by the pubescence), globose, stipitate, densely tomentose, the trichomes dendritic, ca. 0.1-0.3 mm long, ferruginous, and falling easily to the touch as dust, the surface slightly rugose, the line of dehiscence slightly carinate, but not very conspicuous, the base obtuse, the apex acute to obtuse; pericarp 1.6-2.2 mm thick; pedicel 0.5-0.7 cm long. Seed 1.8-1.9 × 1.2-1.4 cm, the testa whitish grayish to brownish when dry, grooved; aril color when fresh not described, blackish to brownish red when dry, the texture dry and thin, laciniate almost to the base, in narrow bands distally.

Distinctive characters.

Virola bombuscaroensis can be recognized by many pubescence characters. Dendritic trichomes cover its branches, petioles, inflorescence axes, and sometimes along the main veins on the abaxial sides of leaves; the abaxial leaf surface always is marked by stellate, sessile trichomes (Fig. 4C ); its fruits are covered by ferruginous trichomes that fall very easily to the touch (Fig. 6C ); the perianth of staminate flowers is densely pubescent on both sides; and the column of filaments has scattered trichomes at the base. Finally, the filament column is straight, not constricted at the apex, and is longer (ca. 1.4 mm) than the anthers (ca. 0.9 mm).

Etymology.

The specific epithet makes reference to the Bombuscaro River in the Podocarpus National Park of southern Ecuador, where most of the collections of this new species were made.

Distribution.

Virola bombuscaroensis is known only from Ecuador (Zamora-Chinchipe Province) (Fig. 18A ). It is found in premontane forest at elevations between 1200 to 1350 m, with a single collection from 1930 m in elevation.

Phenology.

Staminate flowers of Virola bombuscaroensis have been recorded in April and fruits in January. Pistillate flowers were not seen in the studied material.

Common name and uses.

None recorded.

Preliminary conservation status.

Virola bombuscaroensis is Critically Endangered following IUCN criterion B2a. While its very small range from only a single locality justifies this status, V. bombuscaroensis benefits from its occurrence in Podocarpus National Park and surrounding areas, which are highly protected within Ecuador ( Kleemann et al. 2022).

Discussion.

Virola bombuscaroensis is difficult to confuse with other species of Virola described to date. However, it shares the combination of a cordate leaf base, well-separated lateral veins, sessile trichomes on abaxial leaf surface, and fruits with a conspicuous layer of trichomes with V. excisa (described here). Other species with similar leaf morphology, but with fruits with less conspicuous trichomes include: V. calophylla (Fig. 6E ), V. peruviana (Fig. 6K ), and V. schultesii A. C. Sm.; they can be distinguished by the characters in Table 3 .

Other species with similar leaf morphology (i.e., a usually deeply cordate base and well-separated lateral veins) are: V. divergens Ducke, V. mollissima (Poepp. ex A. DC.) Warb., and V. sebifera . However, these species differ in having pediculate trichomes on the abaxial leaf surface (vs. sessile in V. bombuscaroensis ), internally puberulent staminate perianth (vs. densely pubescent), a glabrous filament column (vs. with scattered trichomes at the base; Fig. 10D ) that is shorter (vs. longer) than the anthers. In fruiting material, V. divergens , and V. mollissima are covered with a thick layer of long hairs (at least 1.4 mm long) that differ from V. bombuscaroensis . While the layer of trichomes on the fruit are somewhat similar to the new species in V. sebifera , the fruits are notably smaller (1-1.9 [-2.1] × 0.7-1.4 [-1.7] vs. 2.4 × 1.8-1.9 cm), and V. sebifera usually occurs at lower elevations.

Additionally, compared to the species with with it can be confused, V. bombuscaroensis tends to have longer staminate inflorescences and more obviously pubescent twigs, petioles, and abaxial leaf surface, very often with dendritic trichomes.

Notes.

The specimen J. Homeier 1090 was cited as Virola sp. 1, in Spermatophyta / Checklist Reserva Biológica San Francisco (Prov. Zamora-Chinchipe, S-Ecuador) ( Homeier and Werner 2007), while W. Palacios & M. Tirado 13379 was discussed under V. peruviana in Flora of Ecuador ( Jaramillo et al. 2004).

Two collections from Cajamarca Department, Peru collected at 1500-1700 m elevation, J. Campos & S. Nuñez 4589 (MO!, NY-2 sheets!, UPCB [n.v.]) bearing staminate flowers and J. Campos & S. Nuñez 4188 (MO, NY, UPCB [n.v.]) bearing an infructescence with very immature fruits, have similar leaf morphology to V. bombuscaroensis (i.e., cordate base and abaxial surface with stellate, sessile trichomes). However, these specimens differ in their longer staminate inflorescences (ca. 8 cm vs. ca. 5.4 cm long) and the shorter (ca. 0.4 mm vs. ca. 1.4 mm long), glabrous (vs. pubescent) filament column. Additional, more complete material is needed to assess whether these are conspecific. These specimens have been identified as V. calophylla and duplicates may have been distributed under this name.

Specimens examined.

Ecuador. Zamora-Chinchipe: Area of the Estación Científica San Francisco, road Loja-Zamora , ca 35 km from Loja, 03°58'S, 079°04'W, 1930 m, 6 Apr 2002 (fl ♂), J. Homeier 1090 (MO!); Zamora cantón, Parque Nacional Podocarpus, guardería Rio Bombuscaro , 04°05'S, 078°57'W, 1200 m, [s.d.] Jan 1995 (fr), W. Palacios & M. Tirado 13379 (MO!, UPCB [n.v.]) .

Figures

Figure 4. Comparation of pattern of the lateral veins and trichomes on abaxial leaf surface (below) of the newly described species of Virola and species that are morphologically similar A Virola aguarunana (C. Diaz et al. 7700 A, MO) B V. alvaroperezii (G. Tipaz et al. 1789, MO) C V. bombuscaroensis (J. Homeier 4507, MO) D V. calimensis (M. Monsalve 1769, MO) E V. calophylla (J. E. L. da S. Ribeiro et al. 1138, MO) F V. calophylloidea (C. C. Berg et al. P 18793, MO) G V. cogolloi (A. Cogollo et al. 4198, MO) H V. excisa (C. E. Ceron & F. Hurtado 4147, MO) I V. obovata (R. Vasquez & N. Jaramillo 3822, MO; below from A. [H.] Gentry & J. Revilla 20448, MO) J V. macrocarpa (A. E. Lawrence 675, K below A. E. Lawrence 675, MO) K V. parkeri (A. Monteagudo et al. 10761, MO; below from M. Huaman et al. 334, MO) L V. peruviana (W. H. Lewis et al. 10074, MO) M V. sebifera (R. Aguilar 2171, MO) N V. tuckerae (A. Cogollo et al. 4147, MO) O V. yasuniana (H. Vargas & J. Cerda 678, MO). Scale bars: 1 cm.

Figure 6. Comparison of fruits of newly described Virola species, with those species that are morphologically similar to them, noting the shape, indument, a pericarp thickness A V. aguarunana (C. Diaz et al. 7195, MO) B V. alvaroperezii (D. Rubio et al. 2205, MO) C V. bombuscaroensis (J. Homeier 4507, MO) D V. calimensis (M. Monsalve 158, MO) E V. calophylla (J. J. Pipoly 15614, MO) F V. calophylloidea (S. R. Lowrie et al. 54, MO) G V. cogolloi (D. Cardenas & E. Alvarez 3239, MO) H V. macrocarpa (A. E. Lawrance 675, MO) I V. excisa (W. Palacios 3186, MO) J V. obovata (R. Vasquez & N. Jaramillo 3822, MO) K V. peruviana (D. N. Smith & V. Garcia 13841, MO). L V. parkeri (A. Monteagudo et al. 10761, MO) M V. yasuniana (A. Perez & W. Santillan 4361, MO; right and below from V. Zak & S. Espinoza 5149, MO) N V. tuckerae (A. Cogollo et al. 3924, COL). Scale bars: 1 cm.

Figure 8. Virola bombuscaroensis A branch with staminate inflorescence and detail of trichomes on abaxial surface B partial staminate inflorescence in bud C external surface of staminate perianth (in bud), with detail of trichomes (top right) D medial section of staminate perianth showing the internal surface and androecium, with a close-up of the filament column with trichomes at bas and anthers (right) E branch with infructescence F different views of the fruits, detail of trichomes (left), and open fruit showing the seed with laciniate aril (above). Drawn by Bobbi Angell based on J. Homeier 1090 (A-E MO), and J. Homeier 4507 (F-G MO).

Figure 10. Virola cogolloi A branch with staminate inflorescence, with detail of trichomes on abaxial surface B closeup of partial staminate inflorescence C staminate perianth, with detail of trichomes (left) D medial sections of staminate flower showing the internal surface and androecium, with a closeup of filament column and anthers (right) E partial infructescence and open fruit showing the seed with laciniate aril. Drawn by Bobbi Angell based on A. Cogollo 4198 (A-D MO), and D. Cardenas & E. Alvarez 3239 (E MO).

Figure 18. Geographic distribution of the new species of Virola.