Virola aguarunana D. Santam., 2022

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

1. Virola aguarunana D. Santam. sp. nov.

Type.

Peru. Amazonas: Bagua, distrito Imaza, Comunidad Aguaruna Putuim (anexo Yamayakat), zona de colinas altas 24 SW de Putuim, [05°00'47"S, 078°23'20"W], 700 m, 22 Sep 1994 (fr), C. Díaz, A. Peña, & P. Ataim 7195 (holotype: MO! [accession 04808693, barcode MO-1405111]; isotypes: UPCB [n.v.]). Fig. 5

Diagnosis.

Virola aguarunana was mainly confused with V. calophylla . Both species share stellate and sessile trichomes and well-separated lateral veins. Morphologically, it differs because the new species has sparsely pubescent abaxial leaf surface (vs. densely pubescent), long staminate perianth ([2-] 2.5-2.7 mm vs. 1-2.1 mm long), and fruits that are covered by a dense layer of trichomes (vs. covered with an inconspicuous layer of trichomes).

Tree 16-20 m tall, diameter and inner bark not described. Exudate transparent, oxidizing to red, location of exudate on plant not stated. Twigs 0.18-0.27 cm thick, terete to slightly angled, tomentose to puberulent, trichomes dendritic, sessile, brown to ferruginous, sometimes slightly lenticellate. Leaves young terminal bud 0.8-1 × 0.16-0.18 cm; petiole 0.9-1.5 (-1.7) × 0.18-0.28 cm, slightly canaliculate, sometimes with very short alate, tomentose, the trichomes dendritic or sometimes stellate; leaf blades (10.7-) 14-22.7 × 4-8.5 cm, oblong-elliptic to ovate; adaxial surface of mature leaves that dry pale to dark brown or blackish, the surface smooth, sometimes shiny, glabrous; abaxial surface dries grayish pale to dark brown, sparsely pubescent, the trichomes stellate or sometimes stellate with dendriform trichomes along the main veins, the stellate trichomes 0.1-0.15 mm diameter, sessile, the central part of the trichome reddish, the branches pale brown-reddish or colorless; lateral veins 13-16 per side, 4-6 per 5 cm, spaced 0.8-1.1 (-1.5) cm, on adaxial side, the same color as the adaxial surface, flat, on abaxial surface raised, laterally compressed, tomentose, arcuate-ascending, slightly anastomosing near the margin and without forming a marked intramarginal vein; tertiary veins slightly visible on both leaf surfaces; midvein adaxially flat to slightly elevated, abaxially raised, rounded, laterally compressed or something triangular, tomentose; base acute to rounded, not revolute, flat; margin flat; apex acuminate. Staminate inflorescences 2.2-2.5 cm long, axes flattened, tomentose, the trichomes dendritic, ferruginous; peduncle 0.8-1.1 × 0.1-0.2 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 8-16+ flowers, borne on a receptacle (2-) 3.5-4.5 mm wide; perianth (2-) 2.5-2.7 mm long, obovate, fleshy, brown to brown greenish, connateconnate by 1.3-1.6 mm long, 1.3-1.6 mm long, external surface densely pubescent with ferruginous dendritic trichomes, internal surface moderately pubescent on the lobes; lobes 3, 0.9-1.2 (-1.4) × 0.3-0.8 mm and 0.1-0.2 mm thick, without resinous punctuations when rehydrated; stamens 3, the filament column 0.4-0.5 mm long and ca. 0.2-0.3 mm wide, glabrous, straight or rarely as a bottle shape, not constricted at the apex; anthers 0.6-0.9 mm long and 0.2-0.4 mm wide; apiculus 0.1-0.2 mm long or appearing absent (R. Rojas et al. 486), obtuse, connate. Pistillate inflorescences and pistillate flowers not seen. Infructescence 3.4-5 cm long, with 1-2 fruits, peduncle 1.5-2 cm × 0.35-0.46 cm. Fruits 2.9-3.5 × 1.8-2.2 cm, green or brown (probably due to pubescence) when fresh, pyriform to subglobose (with narrow base), stipitate, densely tomentose, the trichomes dendritic (ca. 0.2 mm long), ferruginous, and falling easily to the touch as dust, the surface slightly rugose, the line of dehiscence smooth to slightly carinate, the base obtuse, the apex acute to obtuse; pericarp 2-2.5 mm thick; pedicel 0.5-0.6 cm long. Seed ca. 2 × 1.6 the testa drying brownish reddish, grooved; aril color when fresh not described, blackish to brownish reddish when dry, the texture dry and thin, laciniate almost to the base, in narrow bands distally.

Distinctive characters..

Virola aguarunana is recognized by its very short staminate inflorescences (2.2-2.5 cm long) with dense fascicles of flowers, relatively thin perianth that is externally densely pubescent and internally moderately pubescent, and a filament column that is shorter (0.4-0.5 mm long) than the anthers (0.6-0.9 mm long). It is further distinguished by its pyriform to subglobose fruits covered with ferruginous trichomes (Fig. 6A ) that fall easy to the touch and leaf blades usually that are narrow with well-separated later veins and scattered pubescence of stellate and sessile trichomes, on the abaxial surface (Fig. 4A ).

Etymology.

The specific epithet honors the Aguaruna people, who live in the area where this species was collected.

Distribution.

Virola aguarunana is known only from the Amazonas Department of Peru (Fig. 18A ). This tree has been collected along creek margins on rocky soils with abundant organic material at 700-800 m elevation. The region is also home to other notable species, including many magnoliids- Compsoneura diazii Janovec ( Myristicaceae), Cremastosperma bullatum Pirie, Cremastosperma yamayakatense Pirie ( Annonaceae), Ocotea imazensis van der Werff, Ocotea leptophylla van der Werff ( Lauraceae)- as well Dacryodes uruts-kunchae Daly, M. C. Martínez & D. A. Neill ( Burseraceae) and Quipuanthus epipetricus Michelang. & C. Ulloa ( Melastomataceae), among many others.

Phenology.

Staminate buds and flowers of Virola aguarunana have been recorded in January, October, and November; pistillate flowers were not seen in the studied material. Fruits have been collected in August and September.

Common name and uses.

No common names or uses are mentioned among the herbarium specimens observed.

Preliminary conservation status.

Virola aguarunana is Endangered following IUCN criteria B1a and B2a. It is known from two localities, has an EOO of 98 km2, and an AOO of 12 km2. Further justifying this status, this very small distribution is combined with occurrence in areas known to be impacted by forest declines driven by shifting agriculture demands ( Antonelli 2022). Of the few species we were able to verify, the most recent was collected in 1997.

Discussion.

Most of the specimens of Virola aguarunana were previously determined as V. calophylla or V. sebifera , both widely distributed in South America. The new species shares some characteristics with V. calophylla , including a mixture of stellate and sessile trichomes and well-separated lateral veins (a feature shared with V. sebifera ). However, V. aguarunana can be distinguished by its sparsely pubescent abaxial leaf surface (vs. densely pubescent; Fig. 4A, E ), longer staminate perianth ([2-] 2.5-2.7 mm vs. 1-2.1 mm long), a filament column that is shorter than the anthers (vs. longer than anthers), and fruits that are covered by a dense layer of trichomes (vs. covered with an inconspicuous layer of trichomes; Fig. 6A, E ). Virola aguarunana shares the following traits with V. sebifera : a filament column that is shorter than the anthers, fruits covered by a dense layer of trichomes, and the same leaf traits as shared with V. calophylla . The new species differs from V. sebifera , by the sessile trichomes on the abaxial leaf surface (vs. usually pediculate; compare with Fig. 4M ) and larger fruits (2.9-3.5 × 1.8-2.2 cm vs. 1-1.9 [-2.1] × 0.7-1.4 [-1.7] cm). Additionally, V. aguarunana can be differentiated in both species for its short and narrow staminate inflorescences with flowers borne in dense terminal fascicles. Further, V. calophylla and V. sebifera tend to have larger leaf blades.

Notes.

The only seed that could be measured is from one of the two fruits of the specimen C. Díaz et al. 7195 (MO), which is not well preserved. The typical seed size for V. aguarunana is likely larger than presented here.

The specimen D. Neill & Dendrology course students 15280 (MO; fr), from Cordillera del Cóndor, Zamora-Chinchipe, Ecuador may correspond to this species, though it is difficult to tell without flowers.

Specimens examined.

Peru. Amazonas: comunidad Aguaruna Putuim, anexo de Yamayakat, 700-750 m, 19 Jan 1996 (♂ fl), C. Díaz et al. 7700A (MO!); Comunidad Aguaruna de Wanás (Km 92 Carretera Bagua-Imacita), Cerros Chinim , 700-800 m, 29 Aug 1996 (fr), C. Díaz et al. 8054 (F [image!], MO!); Comunidad Aguaruna de Kusu-Listra , Cerro Apag , margen derecha Quebrada Kusu , [05°02'24"S, 078°19'12"W], 550 m, 19 Nov 1996 (fl bud), C. Díaz et al. 8086 (MO!); Tayu Mujaji, Comunidad de Wawas , 05°15'25"S, 078°21'41"W, 800 m 25 Oct 1997 (♂ fl bud), R. Rojas et al. 486 (MO!) .

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 5. Virola aguarunana A branch with staminate inflorescence, including detail of abaxial leaf surface B partial staminate inflorescence C staminate perianth, with detail of trichomes (left) D medial sections of staminate perianth, showing the internal surface and androecium, with a closeup of the filament column and anthers (right) E fruit with detail of trichomes (left), with open fruit showing laciniate aril. Drawn by Bobbi Angell based on C. Diaz et al. 7700 A (A-E; MO) and C. Diaz et al. 7195 (F; MO).

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 18. Geographic distribution of the new species of Virola.