Beilschmiedia osacola Aguilar, D. Santam., & van der Werff, 2021

Santamaría-Aguilar, Daniel, Fernández, Reinaldo Aguilar & Werff, Henk Van Der, 2021, Beilschmiedia osacola (Lauraceae) a new species from the Osa Peninsula, Costa Rica, Phytotaxa 498 (3), pp. 197-204 : 198-202

publication ID	https://doi.org/ 10.11646/phytotaxa.498.3.5
persistent identifier	https://treatment.plazi.org/id/03CA87B8-EB5F-747E-FF26-F8CB5631FAB4
treatment provided by	Marcus
scientific name	Beilschmiedia osacola Aguilar, D. Santam., & van der Werff
status	sp. nov.

Treatment

Beilschmiedia osacola Aguilar, D. Santam., & van der Werff View in CoL , sp. nov. ( Figures 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Type:— COSTA RICA. Puntarenas: Golfito, Jiménez , La Palma , La Tarde , camino a la trocha que lleva a Cerro de Oro , 08°34’25”N, 83°30’12”W, 154 m, 27 February 2016 (fl.), R GoogleMaps . Aguilar & D. Santamaría 15554 (holotype MO!; isotypes CR) .

Differs from its Neotropical congeners in its turbinate to campanulate flowers, its tepals fused into a tube, the free lobes much shorter than the fused part, six fertile stamens and the uniformly pubescent ovary.

Tree 30–45 m × 40–90 cm DBH, bole mostly straight, with buttresses up to 1.5 m tall; outer bark reddish, peeling in large plates. Terminal buds ovoid, densely pubescent with more or less erect and straight trichomes, golden to pale brown. Twigs 2 mm across (below the terminal bud), solid, terete, slightly compressed when young, blackish when dry, sparsely pubescent. Leaves alternate; blade 9.5–14 cm long × 2.5–5.5 cm wide, elliptic, glabrous on both surfaces, drying brownish above and olivaceous below, sometimes the lateral veins whitish, base cuneate, plane, apex acute, midrib flat to slightly raised above, raised below with very sparse trichomes, secondary veins (6–) 8–11 pairs, ascending, flat above, slightly raised below, tertiary veins prominent on both surfaces in dried material; domatia absent; petioles 1–1.3 cm long, sparsely pubescent, slightly canaliculate above, rounded below, drying brownish to blackish. Inflorescences 7–10.5 cm, paniculate, in axils of the terminal leaves, axes sparsely pubescent; pedicels 1.2–2 mm long, densely pubescent with white and erect trichomes. Flowers 2–3.5 mm long × 1.5–2 mm wide, whitish to cream, or rather greenish with yellow tepals, drying blackish, the perianth circumcissile in old flowers, leaving the pistil fully exposed on the pedicel; receptacle 0.9–1.2 mm long × 1–2 mm wide, tubular, longer than the tepals, outer surface with appressed and wavy trichomes, the trichomes pale yellow, inner surface with scattered trichomes or only pubescent distally; tepals 6, slightly unequal, the outer ones 0.6–0.7 mm long × 0.5–0.8 mm wide, the inner ones 0.9– 1.1 mm long × 0.8–1 wide mm, elliptic to ovate or triangular, pubescent outside, the trichomes yellowish to whitish, more or less erect and wavy, glabrous near the margin, glabrous inside; androecium of 6 stamens, whorls I and II with filaments 0.2–0.3 mm long, inserted at the base of the tepals, the ventral side with a conspicuous line of trichomes in the middle, the dorsal side pubescent (especially at the base), anthers 2-locular, 0.1–0.2 mm long, oblong, ovate, orbicular, or roundish-triangular, apex truncate to acute, glabrous; whorl III staminodial, 0.6–0.8 mm long, columnar, densely pubescent, with 2 large glands attached near the base; whorl IV staminodial, 0.4–0.6 mm long, more or less triangular, pubescent; pistil 1.2–1.8 mm long, pubescent; ovary 0.6–0.9 × 0.6–1 mm, ovoid; style gradually tapering to the stigma. Fruits ca. 6 cm long × 2.1 cm wide, ellipsoid, dark purple when mature; mature pedicels not seen, immature pedicels ca. 2 mm long, not constricted at the apex in fresh material.

Distribution and habitat:— Beilschmiedia osacola is endemic to Costa Rica. It is known only from the Osa Peninsula, south Pacific coast, where it was found growing in tropical primary rain forests, on well-drained soils with red clays; at 10–210 m elevation. This species is known from six individuals, five around the type locality (La Tarde), and one in the Piro region (R. Aguilar pers. obs.) ( Figure 5 View FIGURE 5 ), which were not formally preserved to be deposited in the herbarium.

Etymology:— The specific epithet refers to the place where the species occurs, the Osa Peninsula, at the southern end of Costa Rica’s Pacific coast, Puntarenas province.

Phenology:— Beilschmiedia osacola has been collected with flowers in February; while the mature fruits were seen, photographed but not yet collected in June.

Discussion:— The most distinctive character of the new species are the small, turbinate to campanulate flowers. Nishida (1999) described flowers of Neotropical Beilschmiedia species as having invariably a shallow receptacle, a character that separates Beilschmiedia from Cryptocarya , which has a deep receptacle that encloses the ovary. The new species has a relatively deep receptacle which largely encloses the ovary, though not quite as deep as in Cryptocarya . The fruits support a placement in Beilschmiedia ; they are seated unprotected on the pedicel, while in Cryptocarya the fruit is enclosed by the accrescent floral tube with remnants or scars of the fallen tepals at the apex of the fruits. In other Neotropical species of Beilschmiedia the tepals are fused only at the very base and the tepal lobes are much longer than the fused bases. In the new species, however, the tepals are fused for more than half their length and the tepal lobes are much shorter than the fused part of the perianth. Beilschmiedia species with a deep perianth tube and short tepals are known from tropical West Africa; an example is B. neoletestui Fouilloy & Hallé (1963: 246) , illustrated in Fouilloy (1965; Plate XV). Whether relationships of the new species lay with African species as suggested by the flower shape or with Neotropical species remains to be investigated.

Beilschmiedia osacola is vegetatively recognized because it is a large tree, the bark is reddish, and peeling in large plates ( Figure 3A–D View FIGURE 3 ), by its alternate leaves, not densely grouped at the apex of the twigs, the lower leaf surface glabrous and not glaucous ( Figure 3G View FIGURE 3 ), with tertiary veins reticulate ( Figure 3H View FIGURE 3 ), and relatively long and thin petioles. The flowers stand out by their tiny size ( Figures 2D–G View FIGURE 2 , 4B View FIGURE 4 ), by the perianth with receptacle on outer surface pubescent, and tepals slightly unequal; the androecium is composed of six fertile stamens (whorls I and II), while the whorls III and IV are staminodial. The stamens of whorl III are columnar, pubescent, with two large glands attached near the base; the ovary is pubescent ( Figure 2E, F View FIGURE 2 ). The new species shares with B. costaricensis (Mez & Pittier in Mez 1903: 228) C.K. Allen (1945: 415) the areolate tertiary venation with free-ending veinlets, but it differs from that species in its uniformly pubescent ovary, the tepals clearly shorter than the hypanthium and the multiflowered and laxly branched inflorescences.

The other Neotropical species of Beilschmiedia with six fertile stamens is B. hexanthera van der Werff (1995: 374) , from French Guiana. This species also has alternate leaves which are not glaucous below, and the staminodes of III whorl are columnar. However, B. osacola has a pubescent ovary (vs. glabrous), and the inflorescence is more spreading with slender axes.

According to Nishida (1999), five of the other species of Beilschmiedia may have a (slightly) pubescent pistil: B. angustielliptica Lorea-Hernández (1995: 47) , from Mexico, and B. riparia Miranda (1953: 75) from Mexico, Honduras, and Nicaragua, as well as three more widespread species, B. costaricensis , from Costa Rica to Peru, B. pendula ( Swartz 1788: 65) Hemsley (1882: 70) from the Antilles and Honduras to Ecuador, and B. tovarensis ( Meissner 1864: 65) Nishida (1999: 696) , from Costa Rica to Bolivia. However, all these species have equal (vs. slightly unequal), and larger tepals (1.3–1.7 × 0.9–1.5 mm vs. 0.6–0.7 × 0.5–0.8 mm), and nine fertile stamens (vs. six fertile stamens). Among these species, B. osacola is most similar to B. costaricensis in its vegetative characteristics, but it can be distinguished by the floral and fruit characteristics presented in the Table 1. Moreover, B. costaricensis usually occurs at high elevations ([100–] 600–3000 m), whereas B. osacola is only known from low elevations so far.

*Measurements from Nishida (1999)

González & Hammel (2007) accepted 10 species of Beilschmiedia , two of them treated as Beilschmiedia sp. 1 (from Pacific slope), and Beilschmiedia sp. 2 (from Caribbean slope). These probably represent undescribed species. The species described here differs from the undescribed species by the number of fertile stamens (6 vs. 9 stamens) and the pubescent ovary (vs. glabrous ovary). Four species with green, not glaucous lower leaf surfaces were mentioned by González & Hammel (2007): B. brenesii Allen (1945: 415) , with opposite or subopposite leaves (vs. alternate); B. costaricensis , see discussion above; and B. sp. 1, B. sp. 2, with larger leaves (21–33 [–39] vs. 9.5–14 cm long).