Pistacia terrazasae, Wheeler & Manchester, 2021

Wheeler, Elisabeth A. & Manchester, Steven R., 2021, A Diverse Assemblage Of Late Eocene Woods From Oregon, Western Usa, Fossil Imprint 77 (2), pp. 299-329 : 300-303

Pistacia terrazasae sp. nov.

Text-fig. 1a–i

H o l o t y p e. Designated here. UF 279-24545 (Textfig. 1b–i).

P a r a t y p e. D e s i g n a t e d h e r e. UF 279-85025

( Text-fig. 1a ).

P l a n t F o s s i l N a m e s R e g i s t r y N u m b e r.

PFN002712 (for new species).

1. Dupéron (1973), 2. Selmeier (2000a), 3. Cheng et al. (2012), 4. Gottwald (2004), 5. Akkemik et al. (2018) * Ray width described as to 5 cells wide, however, it seems probable that is the width of rays with canals.

R e p o s i t o r y. Paleobotany Collections , Florida Museum of Natural History , Gainesville, Florida, USA .

E t y m o l o g y. Named for Teresa Terrazas to acknowledge her comprehensive treatment of the wood anatomy of the Anacardiaceae

T y p e l o c a l i t y. UF 279. About 3 km east of Post,

Crook County, Oregon, USA.

T y p e s t r a t u m a n d a g e. John Day Formation,

Eocene.

D i a g n o s i s. Growth rings distinct. Wood ringporous with a narrow earlywood zone, mostly 1 pore deep, earlywood vessels not contiguous; latewood vessels predominantly in radial multiples, some in clusters. Helical thickenings present. Perforation plates exclusively simple. Intervessel pitting alternate. Vessel-ray parenchyma pits with reduced borders, rounded to oval in outline. Fibers non-septate. Axial parenchyma not common, scanty paratracheal. Radial canals present. Rays heterocellular with a few marginal rows of square to upright cells. Crystals in marginal ray parenchyma cells.

D e s c r i p t i o n. Growth rings present, marked by radially flattened latewood fibers, and differences in vessel diameter and density between latewood and earlywood of subsequent rings. Ring-porous.

Earlywood vessels solitary and rounded to slightly oval in outline, earlywood pore zone 1(–2) pores deep, not contiguous; latewood vessels mostly in radial multiples and clusters, solitary latewood vessels angular in outline (Textfig. 1a, b); average tangential diameter of earlywood vessels 89 (22) µm, range 57–139 µm; perforations exclusively simple ( Text-fig. 1c ); intervessel pits alternate (not angular in outline) ( Text-fig. 1c, d ), 7–9 µm in horizontal width; vesselray parenchyma pits with reduced borders and rounded to oval in outline ( Text-fig. 1e ), occasionally irregular in shape, most commonly in upright/square ray cells; prominent helical thickenings along the full length of narrow vessel elements ( Text-fig. 1c, d ); mean vessel element length 354 (38), range 275–435 µm; tyloses abundant, bubble-like in earlywood vessels, more widely spaced in latewood vessels.

Fibers non-septate, walls medium-thick, pitting not observed.

Axial parenchyma rare, scanty paratracheal.

Rays 1–3(–4)-seriate, uniseriates low, usually less than 10 cells high ( Text-fig. 1d, g, h ). Multiseriate rays heterocellular, body of procumbent cells, with 1–2(– 4) marginal rows of upright cells ( Text-fig. 1e ); total multiseriate ray height average 308 (100), range 135–555 µm; 4–5/mm. Solitary crystals occasional in upright/square marginal ray cells ( Text-fig. 1f, h ), some crystalliferous cells enlarged, rarely chambered. Radial canals present (Textfig. 1i), oval in outline, canal size – width by height ranging from 40 × 70 µm to 60 × 110 µm, with thin-walled walled epithelial cells.

C o m p a r i s o n s w i t h e x t a n t w o o d s.A search of InsideWood for ring-porous wood (3p), vessels in radial multiples of four or more common (10p), simple perforation plates (13p), alternate intervessel pits (22p), vessel-ray parenchyma pits with reduced borders (31p), helical thickenings along the length of the vessel elements (36p 37p), and radial canals (130p) returned five species of Pistacia and Rhus microphylla ENGELM. in the Anacardiaceae . Rhus microphylla has a broad earlywood zone, while Pistacia species have narrow earlywood zones, usually with one discontinuous row (more rarely two rows) of enlarged solitary earlywood pores ( Fahn et al. 1986, Terrazas 1994, Abundiz-Bonilla et al. 2004). Consequently, we assign these Post Hammer woods to Pistacia .

Pistacia is a genus of shrubs to small trees with a disjunct distribution ( Mabberley 2017). Seven species occur from the Mediterranean basin to Central Asia ( P. atlantica DESf., P. integerrima J.L.STEWART , P. khinjuk STOCKS , P. lentiscus L., P. palaestina BOISS. , P. terebinthus L., P. vera ) L., two species occur in eastern Asia ( P. chinensis BUNGE , P. weinmannifolia J.POISS. ex fRANCH.), two species are distributed from the southwestern United States to Central America ( P. mexicana KUNTH , P. texana SWINGLE ) ( Yi et al. 2008). InsideWood has reference images of Pistacia chinensis (FRI 547, CAFw 8636). P. khinjuk (Lw s.n.), P. lentiscus (SJRw 14465), P. mexicana (FPAw 27837, MADw 12256), and P. palaestina (MADw 26695). The latewood of Pistacia terrazasae does not have a pronounced diagonal or tangential arrangement and thus resembles the latewood of P. lentiscus (SJRw 14465) and P. mexicana (MADw 12256) more than the other species which usually have a pronounced tangential to diagonal-dendritic arrangement. Ray widths in this new species also are similar to P. lentiscus and P. mexicana . According to Terrazas (1994), who examined wood of 10 extant Pistacia species, multiseriate rays in P. mexicana and P. lentiscus were “most commonly 2–3” cells wide, implying that in other species multiseriate rays usually are 3–5. Appendix I of her dissertation (p. 308) shows the quantitative ray and vessel element features of these two species are similar.

Pistacia lentiscus is found from the Canary Islands across southern Europe from Portugal to Greece and Turkey, across North Africa from Morocco to Egypt and the Middle East; P. mexicana is found in southern Texas, Mexico, Guatemala, and Honduras (AL-Saghir 2010). Both species are evergreen, which is unusual for ring-porous species because ring-porous species almost always are deciduous ( Boura and De Franceschi 2007). Yi et al. (2008), using molecular data, placed these two species in section Lentiscus , while AL-Saghir (2010, 2012), using morphological data (almost exclusively leaf characters), placed them in section Lentiscella. Earlier phylogenetic analyses also placed these two widely separated geographically species in the same section ( Parfitt and Baldenes 1997).

C o m p a r i s o n s w i t h f o s s i l w o o d s. Dupéron (1973) created the genus Pistacioxylon DUPÉRON to accommodate a late Eocene/Oligocene wood with features found in ring-porous species of Pistacia . Selected features of the Pistacioxylon species described to date are compared with Pistacia terrazasae ( Tab. 1). This Post Hammer wood type and the other species assigned to Pistacioxylon have a combination of wood anatomical features unique to Pistacia . We suggest all could be assigned to Pistacia to indicate that their anatomy is indistinguishable from that of the extant genus.

C o - o c c u r r i n g f r u i t s / s e e d s. Manchester and McIntosh (2007) illustrated a silica fruit cast with characters similar to those of extant Anacardium L., Cyrtocarpa KUNTH , and Pistacia from the same locality (UF 279). It is possible that this wood and that fruit came from the same source plant, given they are the only Anacardiaceae known at locality UF 279. However, without direct attachment between them or repeated co-occurrences this cannot be established. The Nut Beds flora included a fossil fruit, Pistachioides striata MANCHESTER (Manchester 1994), which shares many features with pistachio nuts, but it was not assigned to the modern genus because of insufficient preservation of anatomical details. Although numerous silicified woods are preserved at the Nut Beds, including some Anacardiaceae , none of them resemble Pistacia .

R e m a r k s. Xie et al. (2014) hypothesized that Pistacia originated near the Eocene-Oligocene boundary at 37.60 Ma. The minimum age for the Post sites is 36.21 ± 0.26 Ma ( Manchester and McIntosh 2007), which places Pistacia terrazasae near this hypothesized time of origin. It is the oldest known occurrence of a wood with features of Pistacia and the only one known from the USA. Ramírez and CevallosFerriz (2002) described Pistacia marquezii J.L.RAM. et CEV. - fERRIZ, based on Oligocene leaves (Pie de Vaca Formation, Mexico) and that they thought most similar to present-day P. chinensis . They used this similarity to support the concept of exchange between low-latitude North America and Asia. The question remains whether this Oregon fossil wood is evidence for a migration of Pistacia from Asia to Mexico and the American Southwest via the Pacific Northwest.

Figures

Text-fig. 1. Pistacia terrazasae sp. nov., a: UF 279-85025; b–i: UF 279-24545. a: Ring-porous wood with widely spaced solitary earlywood vessels; latewood vessels in radial multiples of 4 or more and in clusters, TS. b: Growth ring boundary, fiber walls thin to thick, TS. c: Simple perforation plates, alternate intervessel pits, helical thickenings in vessels, TLS. d: Multiseriate rays to 4-seriate, tyloses in vessels, helical thickenings throughout body of vessel element, and alternate intervessel pitting, TLS. e: Vessel-ray parenchyma pitting with reduced borders, oval in outline, RLS. f: Marginal row of upright cells, one inflated and crystalliferous, procumbent body cells, RLS. g: Multiseriate rays mostly 3-seriate, occasionally 4-seriate, uniseriate rays usually <10 cells tall, TLS. h: Ray with enlarged crystalliferous marginal cell, to left of C, TLS. i: Ray with canal, TLS. Scale bars: 200 µm in a, g; 100 µm in b, d, h; 50 µm in c, i; 20 µm in e, f.