Schinopsis boqueronensis V. Mogni & L. Oakley, 2014

Mogni, Virginia Y., Oakley, Luis J., Jiménez, María Vera & Prado, Darién E., 2014, A new tree species of Schinopsis (Anacardiaceae) from Paraguay and Bolivia, Phytotaxa 175 (3), pp. 141-147 : 142-145

Schinopsis boqueronensis V. Mogni & L. Oakley , sp. nov. ( Fig. 1 & Fig. 2 )

Species S. heterophylla similis sed foliis simplicibus oblongatis vel ovatis, rara oblongo-lanceolatis, nervis lateralibus foliorum numerosis atque densis, sub angulo 60–90º patentibus, parallelis, petala 5, interdum 6, samara breviter tricornuta, differt.

Type:— PARAGUAY. Presidente Hayes: Ruta trans-chaco, entre Pioneros y 25 Leguas , a la derecha del camino en dirección oeste-este, 22,73º S, 59,69º W, 16 December 2011, M . Vera , V . Mogni & L . Oakley 4240 (holotype FCQ!) .

Tree 12 to 15 m tall, dark bark fracturing into irregularly quadrangular plates. Reproductive short-shoots puberulent and spineless. Spines usually present in long-shoots, 0.37–7.35 × 0.14–0.63 cm. Leaves subcoriaceous, simple to imparipinnately compound; petioles sparsely puberulent on margins and sometimes narrowly winged, frequently longer in pinnate leaves (0.45–4.03 cm) than in simple ones (0.25–1.81 cm). Blades glabrate or sparsely puberulent on the margins and principal vein; margin entire to undulate; abundant secondary veins, considerably lighter coloured and almost parallel, with a divergence of 60° to 90° from the principal vein; upper surface shiny, with epicuticular wax-forming punctations, mainly concentrated on the main vein; lower surface grey to pale green, densely wax-dotted except for the veins. Simple leaves oblong, ovate, oblong-lanceolate, sometimes reniform, 1.20–6.26 × 0.63–2.20 cm; apex obtuse, to emarginate or obcordate, less commonly sub-acute, sometimes mucronate; base rounded, obtuse to gradually cuneate. Compound leaves imparipinnate, rarely paripinnate, 2.98–29.51 × 2.45–10.14 cm, 1–9 pairs of pinnae; rachis subquadrangular, pubescent; leaflets asymmetric, sessile to subsessile, generally oblong-lanceolate to lanceolate, ovate, at times obovate or reniform, 0.54–7.29 × 0.48–5.89 cm, the terminal leaflet frequently larger than the rest; apex subacute, obtuse, to emarginate, usually mucronulate; base cuneate to obtuse or rounded, very rarely lobate. Inflorescence a pubescent terminal panicle, very short-pedunculate; bracteoles lanceolate or ovate-lanceolate, concave, ciliate and caducous. Imperfect flowers, subsessile; sepals 5, imbricate, ovate to suborbiculate with obtuse to rounded apex, ciliate on the margins, 1.28–1.41 × 0.84–1.02 mm; petals 5, but occasionally 6, 1.89–2.29 × 0.77–1.20 mm, greenish-white to cream-coloured, concave, ovate-elliptic, apex rounded, principal vein prominent, exceptionally 2 principal veins and consequently a dentate apex. Pistilate flowers not seen. Staminate flowers with 5 stamens, approx. 3 mm long, anthers half the length of to equalling the filaments. Fruit a lustrous and cultriform samara, 2.5– 3.25 cm long, with persistent calyx; seminiferous portion sub-ovoid to rhomboid, 1–1.33 × 0.8–1 cm, with evident and prominent lignified styles, persistent on the pericarp, wing 1–1.6 × 0.83–1 cm, apex obtuse; dorsal margin straight or slightly concave, the opposite margin convex.

Distribution and habitat:—Endemic to the Bolivian-Paraguayan Chaco; up to now it has been found only in central-west Paraguay in Presidente Hayes, Boquerón and Alto Paraguay departments, and in the south-east of Bolivia in the Santa Cruz department ( Fig. 3 ). The species grows between 130–900 m a.s.l. in the drier Western Chaco phytogeographical region (sensu Prado, 1991; Prado 1993a), and it is also found in transitional areas with the more humid Eastern Chaco. It is often associated with sand dunes, and in savannas dominated by the grasses Elionurus muticus (Spreng., 1827: 32) Kuntze (1898: 350) and Aristida mendocina Phil. (1870: 205) , where it coexists with other species of the genus such as S. cornuta Loes. (in Loesener & Herzog, 1915: 86) and S. lorentzii . It is also associated with other arboreal elements ( Spichiger et al. 2005), such as Astronium fraxinifolium Schott (1827: 404) , Jacaranda cuspidifolia Mart. (1841: 51) , Aspidosperma pyrifolium Mart. (1824: 60) , Tabebuia aurea ( Silva Manso, 1836: 40) Benth. & Hook. f. ex S. Moore (1895: 423) and Pterogyne nitens Tul. (1843: 140) .

Schinopsis boqueronensis also grows in open forests together with the species of Schinopsis mentioned above and Aspidosperma quebracho-blanco Schltdl. (1861: 137) , Ziziphus mistol Griseb. (1874: 99) , Celtis ehrenbergiana ( Klotzch, 1847: 538) Liebm. (1851: 339) var. discolor (Hunz. & Dottori, 1976: 130) L. Oakley & D. Prado (2013: 127) , Chloroleucon chacoense ( Burkart, 1947: 513) Barneby & Grimes (1996: 140) , Salta triflora (Griseb., 1879: 89) Adr. Sánchez (2011: 708) , Mimosa castanoclada Barneby & Fortunato (1987: 167) , Senegalia emilioana (Fortunato & Ciald., 1996: 217) Seigler & Ebinger (2006: 51) and Vachellia aroma (Gillies ex Hook. & Arn., 1833: 206) Seigler & Ebinger (2005: 143) .

Etymology:—The species epithet derives from ‘Boquerón’, a department of Paraguay where the species is particularly frequent.

Additional specimens examined (paratypes):— BOLIVIA. Santa Cruz: Prov . Cordillera, 27 de Noviembre y Parapetí, Chaco Boreal , March 1935, T . Rojas 7252 ( LIL!)—cited in Muñoz (1990) as S. heterophylla ; Parque Nacional Kaa Iya del Gran Chaco , Laguna Azul (puesto ganadero), 24 May 1998, A . Fuentes 2397 ( CTES!, LPB, MO, USZ) .— PARAGUAY. Alto Paraguay: Capitán Mayor Pablo Lagerenza , 20º S, 60º 45’W, 16 April 1978, A . Schinini & E . Bordas 15076 ( CTES!) ; Boquerón: Filadelfia, 18 February 1987, I . Basualdo 840 ( FCQ!, MO); 17 km al norte de Filadelfia en dirección a Montanía , 10 March 2005, R. H . Fortunato 8640 ( CTES!, SI!); Ruta Transchaco a la derecha del camino dirección este-oeste, Parque Nacional Tte. Enciso , 20,92º S 61,83º W, 14 December 2011, M . Vera, V . Mogni & L . Oakley 4227 ( FCQ!); Ruta Transchaco a la izquierda del camino dirección este-oeste, Parque Nacional Tte. Enciso , 20,90º S 61,84º W, 14 December 2011, M . Vera, V . Mogni & L . Oakley 4238 ( FCQ!); a la derecha de camino en dirección norte-sur, a 25 km de Neuland, 22,78º S 59,94º W, 15 December 2011, M . Vera, V . Mogni & L . Oakley 4239 ( FCQ!); Parque Enciso, Ruta Transchaco km 656, 600 km al noroeste de Asunción 21º 13’S 61º 30’W, 26 January 1984, E. L . Little Jr. 40070 ( G, MO, PY!); km 412, ruta IX Carlos A . López, 2 km del cruce Loma Plata, 12 January 1990, T . Florentín Peña, L . de Molas, A . Aguayo & M . Quintana 650 ( CTES!); Ruta Transchaco , 21º 26’ S 61º 25’ W, 7 March 1979, A . Schinini 16444 ( BACP, CTES!, SI!) –cited in Muñoz (1990) as S. heterophylla .

There exists a chance that further specimens of this new species are stored in other herbaria, probably misidentified under S. heterophylla ( Navarro 2004, Mereles 2005, Navarro et al. 2006). For example, additional specimens from Bolivia deposited in the LPB and HSB herbaria could potentially be attributed to S. boqueronensis .

Discussion:—The newly described species, S. boqueronensis , closely resembles S. heterophylla which occurs in the Argentinean central Chaco. The two species may be readily distinguished, however, on leaf venation and morphology, staminate flowers and samara pericarp, as summarized below:

Figures

FIGURE 1. Schinopsis boqueronensis. A. Brachyblast with compound leaves and inflorescence. B. Macroblast fragment usually found in lower positions in the tree crown, showing leaf polymorphism and spines. C. Staminate flower. D. Samara.

FIGURE 2. A. Individual of S. boqueronensis. B. Bark in detail. C, D, E. Leaf polymorphism. D. Inflorescence. F. Staminate flower. G. Samara.

FIGURE 3. Distribution map of S. boqueronensis in South America.