Protium aguilarii D.Santam, 2017

Santamaria-Aguilar, Daniel & Lagomarsino, Laura P., 2017, Two new species and a new combination in Protium (Burseraceae) from Costa Rica, PhytoKeys 76, pp. 89-113 : 89-92

Protium aguilarii D.Santam sp. nov. Figs 1 , 2 , 3

Diagnosis.

Protium aguilarii most closely resembles Protium costaricense (Rose) Engl. and Protium pilosissimum Engl., for their leaves with petiole, rachis, and leaflets that are hispidulous on the abaxial side and leaflets of comparable in size and coloration in herbarium material, but differs from both for its glabrous pistil and fruits (vs. pubescent).

Type.

COSTA RICA. Puntarenas: Reserva Forestal Golfo Dulce, Osa Peninsula, Rancho Quemado , ca. 15 km W of Rincón, on forested slopes at NW end of valley, near Fila Ganado , 08°33'N, 083°34'W, 300-400 m, 29 May 1988 (fr), B. Hammel, G. Herrera, M. M. Chavarría & Á. Solís 16885 (holotype: MO-6664125!; isotypes: CR-51404! [ex- INB], NY-01189275, digital image!) .

Tree, 8-15 m tall × 6-18 cm DBH, lacking stilt roots; external bark white (D. Santamaría et al. 9851). Resin transparent when fresh, a little sticky, aromatic. Twigs 2-4 mm diam, appressed-pubescent with simple or malpighiaceous, pale brown tri chomes 0.05-0.6 mm long, sparsely lenticellate, solid, never stained white. Leaves 2-4-jugate, (12.5-) 19.5-33.8 cm long; petiole (2.3-) 3.3-6.3 cm long, 0.2 cm diam, semi-terete, smooth or slightly striate; rachis (2.6-) 3.5-11.8 cm long, terete, smooth or slightly striate; petiole and rachis hispidulous with simple, pale brown trichomes 0.1-0.5 mm long; lateral petiolules 0.3-1.7 cm long, with pulvinuli evident on both ends, smooth or slightly striate on both sides, rounded, hispidulous with yellowish brown trichomes; terminal petiolule 1.9-4.1 cm long, pulvinulus conspicuous; basal pair of leaflets 5.2-10 × 2-4.3 cm, elliptic to ovate, obtuse at the base; other lateral leaflets 6.7-13.2 × 2.6-5 cm, elliptic to ovate, obtuse to subcuneate at the base (with one side sometimes asymmetric); the terminal leaflet 7.3-14.2 × 2.7-5.8 cm, ovate, elliptic, base obtuse to subcuneate and symmetrical; apex acuminate, the acumen 0.7-1 cm long; margin entire; leaflets drying dark brown or olivaceous above and pale brown or olivaceous below; secondary venation brochidodromous, secondaries in 7-10 pairs of secondary veins, ascending, weakly arcuate, the spacing irregular, perpendicular intersecondaries sometimes present, intercostal tertiaries alternate or mixed percurrent tertiary; on abaxial side the midrib prominent, dense hispidulous, with trichomes 0.06-0.55 mm long, yellowish brown, the secondary veins prominent, with trichomes similar to the midrib, the higher-order veins prominulous, with scattered trichomes, the rest of the surface with scattered trichomes, not papillae; on adaxial side the midrib lightly prominent to flat, hispidulous, secondary veins flat, scattered hispidulous to almost glabrous, the higher-order veins flat almost glabrous, the rest of surface nearly glabrous. Inflorescences fasciculate, axillary (sometimes at leafless nodes), staminate inflorescences unknown, pistillate inflorescences ca. 0.6 cm long (0.9-1.2 cm in fruits), much shorter than the petiole, branching at the base, not flexuous, all axes densely pubescent with simple, yellowish brown or whitish trichomes; bracts subtending the inflorescences ca. 1.3 mm long, lanceolate, acuminate to obtuse at the apex, densely pubescent abaxially; those on primary axes ca. 0.6 mm long, broadly ovate, obtuse at the apex, densely pubescent abaxially; bracteoles subtending flowers ca. 0.8 mm long, triangular, acuminate at the apex, pubescent abaxially. Flowers 4-merous, the pedicel ca. 2.2 mm long (ca. 3 mm in fruit), sparsely pubescent with trichomes ca. 0.2 mm long. Staminate flowers unknown. Pistillate flowers with calyx 1-1.16 × 2.3 mm, sparsely pubescent on abaxial side with trichomes ca. 0.1 mm long, the lobes ca. 0.4 mm long, rounded to depressed-deltate, much taller than the disk, often persistent in fruit; petals white, ca. 2.6 × 0.9 mm, distinct, suberect at anthesis, lanceolate, sparsely appressed-pubescent on abaxial side with yellowish brown to whitish trichomes ca. 0.1 mm long, glabrous but papillose on the adaxial side, papillose and involute marginally, inflexed-apiculate at the apex (the apiculum ca. 0.2 mm long); disk ca. 0.4 tall × 0.2 mm thick, glabrous; staminodes 8, 1.66-1.8 mm long, the antepetalous almost equaling than antesepalous, the filaments ca. 0.9 mm long, flat, the anthers ca. 0.6 mm long, lanceolate, subcordate at the base; pistil ca. 1.5 × 1 mm (at the base), ovoid, glabrous, the style ca. 0.8 mm long, stigma lobes 4, globose, densely papillose. Fruits 1.6-1.8 × 1.2-1.4 cm, subglobose to slightly obliquely ovoid, green (possibly immature), obtuse at the base, acuminate at the apex, sometimes weakly curved, smooth and glabrous, stipitate (the stipe ca. 0.2 cm long); pseudoaril present, color unknown; pyrenes, 1 or 2 usually developing, 1.1-1.4 × ca. 1.2 cm, smooth, broadly ovate, obtuse at the base, acuminate at the apex, bony, the wall ca. 0.75 mm thick, yellowish; funicular scar ca. 0.7 cm long, usually not very deep, without a rib in the middle.

Habitat and distribution.

Protium aguilarii is endemic to Costa Rica, where it is restricted to the Osa Peninsula, on the southern Pacific coast in Puntarenas Province. It occurs in primary forest, at 150-400 m elevation. In Aguabuena, Rincón de Osa, this species occurs in well-drained forest on undulating terrain, with many palms and large lianas; here, it co-occurs with Brosimum utile (Kunth) Oken ( Moraceae ), Carapa Aubl. ( Meliaceae ), and Symphonia L. f. ( Clusiaceae ) (see, for example, K. Thomsen 226). In Rancho Quemado, Protium aguilarii is a small, infrequent tree on mountain ridges, where it is sympatric with tree species that are not very common in the area, or even the country as a whole, including Faramea permagnifolia Dwyer ex C. M. Taylor ( Rubiaceae ), Hirtella papillata Prance and Licania corniculata Prance ( Chrysobalanaceae ), Oecopetalum greenmanii Standl. & Steyerm. ( Metteniusaceae ), and Ruptiliocarpon caracolito Hammel & N. Zamora ( Lepidobotryaceae ).

Phenology.

Protium aguilarii is known from only six fertile collections (one of these with flowers in bud). Pistillate flowers have been collected in April, and fruits in February, May, June, and December.

Common name.

Copalillo (Spanish; Costa Rica, K. Thomsen 683).

Etymology.

The epithet of this new species honors Reinaldo Aguilar Fernández for his important contributions to botany and his dedicated study and devoted collection of the plants of the Osa Peninsula for more than 25 years. He has become the world’s expert in the flora of this remarkably species-rich and beautiful corner of the world. This species is further dedicated to him in appreciation of his support and intellectual stimulation.

Discussion.

Protium aguilarii can be recognized by the combination of leaves with 5-9 leaflets with hispidulous pubescence on the petiole, rachis, petiolules, abaxial side of the leaflets, and inflorescence axes; leaflets with a distinct marginal vein that is visible on the abaxial side; short inflorescences and infructescences; flowers that are 4-merous, with the petals appressed-pubescent on the abaxial side and glabrous on the adaxial side; and glabrous pistils. The new species resembles, and has been confused with, Protium costaricense , which, as treated here, is known only from the Caribbean slope of Nicaragua, Costa Rica, and Panama. Both species share hispidulous pubescence on the leaflets and inflorescences, but Protium aguilarii has a glabrous pistil (vs. densely pubescent in Protium costaricense ), short inflorescence (ca. 0.6 vs. 1.6-6.5 cm long), petals that are glabrous on the abaxial side (vs. sparsely pubescent), and secondary venation brochidodromous (vs. eucamptodromous). Protium aguilarii also has usually shorter (non-basal) leaflets than Protium costaricense (6.7-13.2 vs. 10.5-17.5 cm), and glabrous fruits (vs. minutely pubescent with scattered trichomes), with a stipitate base, the stipe ca. 0.2 cm long (vs. sessile or with stipitate ca. 0.1 cm long). Additionally, Protium aguilarii differs from Protium costaricense by its smooth (vs. rugose) pyrene. In Costa Rica, others species with glabrous pistils or pistillodes are Protium aracouchini Marchand, Protium hammelii (described here), Protium panamense (Rose) I. M. Johnst., and Protium ravenii D. M. Porter. Unlike Protium aguilarii , these species have nearly glabrous leaves and other vegetative parts. Protium aguilarii also shares some similarities with the South American Protium pilosissimum including short inflorescences and pubescent leaflets but it differs by its pubescent pistil or pistillode and fruit (vs. glabrous in Protium aguilarii ).

Additional material examined.

Costa Rica. Puntarenas: Osa, Bahía Chal, La Parcela , 08°43'50"N, 083°27'17"W, 150 m, 25 Jul 1996 (fl bud), R. Aguilar 4593 (CR-2 sheets, F); Bahia Chal , La Parcela, 08°43'50"N, 083°27'17"W, 150 m, 12 Dec 1996 (fr), R. Aguilar 4746 (CR); Rancho Quemado , camino a Drake , parte mas elevada del camino, 200 m al Este de la torre del ICE, en una trocha que lleva al Tierra de Conservacion de Rancho Quemado , 08°41'33"N, 083°35'35"W, 350 m, 04 Apr 2008 (♀ fl), R. Aguilar & X. Cornejo 11115 (MO, NY-digital image, USJ); Rancho Quemado , siguiendo a fila Ganado, 08°43'30"N, 083°35'30"W, 200-450 m, 26 Nov 1991 (st), J. Marín & G. Herrera 306 (CR-2 sheets); Sierpe, Peninsula de Osa , subiendo hacia el Cerro Chocuaco, desde el Bajo de San Juan , 400 m, 12 Jan 1991 (st), C.O. Morales 262 (USJ); Distrito de Sierpe , Peninsula de Osa , entre Rancho Quemado y Drake, trocha al sur, sobre la fila, antes de llegar a la torre, 08°41'30"N, 083°35'28"W, 375 m, 21 Mar 2016 (st), D. Santamaría et al. 9851 (CR); Peninsula de Osa , Aguabuena, 3.5 km W of Rincón, 1 km N of BOSCOSA station, 08°43'N, 083°31'W, 350 m, 09 Jan 1993 (fr), K. Thomsen 226 (CR, NY-digital image, USJ); Peninsula de Osa , Aguabuena, 3.5 km W of Rincón, 1 km N of BOSCOSA station, 08°43'N, 083°31'W, 350 m, 13 Nov 1992 (st), K. Thomsen 683 (CR); Peninsula de Osa , Aguabuena, 3.5 km W of Rincón, 1 km N of BOSCOSA station, 08°43'N, 083°31'W, 350 m, 30 May 1993 (st), K. Thomsen 707 (CR); Peninsula de Osa , Aguabuena, 3.5 km W of Rincón, 1 km N of BOSCOSA station, 08°43'N, 083°31'W, 350 m, 18 Jun 1993 (fr), K. Thomsen 807 (CR, NY-digital image) .

Figures

Figure 1. Protium aguilarii. A Branch with inflorescences B Venation C Pubescence on the leaf rachis and petiolules D Inflorescences E Female flower, with perianth partially removed F Fruits. A-D from R. Aguilar 4593, CR E from R. Aguilar & X. Cornejo 11115, CR F from K. Thomsen 226, CR. Drawing by Jessica Jimenez.

Figure 2. Protium aguilarii. A Trunk and bark B Twigs C Branch with leaves D Leaves showing abaxial side of leaflets E Leaf showing adaxial side F Leaflet bases G Venation H Flower. Photo credits: Reinaldo Aguilar (A-G) from D. Santamaria et al. 9851; and Xavier Cornejo (H) from R. Aguilar & X. Cornejo 11115.

Figure 3. Distribution of Protium aguilarii and Protium hammelii.