The Piedra Chamana fossil woods (Eocene, Peru), II

this contribution presents descriptions of 14 fossil woods from the Piedra Chamana Fossil Forest in Peru, an assemblage of fossil woods and leaves dated at 39 Ma (late Middle Eocene). It is part two of the descriptions of the non-monocot angiosperm fossils from the site (see Woodcock et al. 2017). the woods are assigned to the subfamilies Bombacoideae, Bombacoideae / Malvoideae, Byttneroideae, Grewioideae, and Sterculioideae of Malvaceae and the families Melastomataceae, Muntingiaceae, rubiaceae, rutaceae, and Sapindaceae. Malvalean taxa make up around one-third of the wood types. Many of the woods are identifiable to modern-day genera or groups, including genera with species counted among the hyperdominant trees of the New World forests. represented vegetation types include mixed freshwater swamp with Avicennia , seasonally flooded forest, and lowland tropical forest with a dry aspect. The assemblage shows floristic similarities to extant South American lowland tropical forest, particularly the seasonally flooded forests growing along white water rivers (várzea); however, the dry forest association has a less clear analog in the present-day tropics. Vessel elements, axial parenchyma, and storied; 2–3 tiers millimeter. Crystals

growing in a coastal location (one of the taxa present is the mangrove genus Avicennia). Included here are descriptions of an additional 14 wood types, which are referred to the families Malvaceae, Melastomataceae, Muntingiaceae, rubiaceae, rutaceae, and Sapindaceae.
Information sources utilized include databases for woods and fossil woods, primarily InsideWood (2004-onwards, see also Wheeler 2011) andrichter &Dallwitz (2000-onwards); published anatomical descriptions; regional wood atlases including Détienne & Jaquet (1983), Acevedo & Kikata (1994), and Sonsin et al. (2014); the list of fossil wood names compiled in Gregory et al. (2009); and wood slides collections at Harvard (Bailey-Wetmore Wood and Slide Collection, Aw) and those of the first author. Analyses of affinity 1) provide a list of coded characters in the InsideWood database that are unique to the fossil and taxa under consideration as closest relatives, and 2) discuss proposed affinities with reference to a) wood-anatomical characteristics at the species, genus, and supra-generic levels, b) dissimilarities with respect to the coded IAWA characters, and c) similarities and dissimilarities with respect to other, non-coded characters. Modern woods are the most important point of comparison because of the amount of information available in databases, published descriptions, and systematic treatments, but fossil woods are also considered where affinity is suggested. In most cases, the fossil woods show greatest correspondence with modern woods and are named to extant genera. One wood is referred to a previously described fossil taxon (Grewinium canalisum (Bande & Srivastava) Srivastava & Guleria), and one to a newly established form genus (Miconioidea). Characterization of the occurrence and ecology of the represented taxa draws on sources including the Global Biodiversity Information Facility database (GBIF 2001-onwards), the Useful tropical Plants database (tropical. theferns.info), and regional floras including Gentry (1993) and Pennington et al. (2004). the Plant List (2010) was used to verify nomenclature and for information about species diversity of genera.

Malvaceae
Nine of the wood types show closest correspondence to Malvaceae, a large, diverse group currently under taxonomic revision (Stevens 2001-onwards). Woods in the order Malvales generally have non-septate fibers and apotracheal parenchyma that is diffuse or diffuse-in-aggregates to banded (InsideWood 2004-onwards). rays with tile cells are restricted almost entirely to Malvaceae, only being reported as variably present in one genus of Dipterocarpaceae (InsideWood 2004-onwards). However, tile cells are not universally present in Malvaceae and do not occur in some subfamilies. Designations as to tile cell type are as outlined in Manchester and Miller (1978): Durio typeapproximately the same height as procumbent cells, and usually very narrow in tangential section (Chattaway 1933); Intermediate type -somewhat to two times the height of the procumbent cells; and Pterospermum type -two or more times the height of the procumbent cells. Note that these definitions differ from those in the IAWA features list (IAWA Committee 1989) and also that determinations in the literature, particularly for the Intermediate and Pterospermum types, may be inconsistent; comparisons made here rely on photographs or the wood slides collections consulted. In Malvaceae, intervessel and vessel-axial parenchyma pits are often similar, but when they differ, vessel-parenchyma pitting generally consists of pits approximating the intervessel pits in size intermixed in the same cells with pits that are simple or with reduced borders and variably enlarged. table 1 presents information on anatomical characteristics of the subfamilies of Malvaceae based mainly on information in the InsideWood database (InsideWood 2004-onwards) and with family groups as constituted on the Angiosperm Phylogeny website (Stevens 2001-onwards) and in recent taxonomic treatments. the information presented should be considered provisional pending more systematic review of the wood anatomy of the family. Brownlowiodeae 9 [7 rare ± -± -min(-small) -? (Stevens 2001-onwards) Sterculioideae 13 [11] ± ± rare 2 --min-small -? (Wilkie et al. 2006) Dombeyoideae 21 [5] rare ± Helmiopsis ± ± min-small +? (Stevens 2001-onwards)   → Subfamilies/taxa represented in the assemblage in boldface. Abbreviations: DP = diffuse porous, Vdia = vessel diameter, Vden = vessel density, rP / SrP = ring porous to semi-ring porous, Vx's = vessels in radial multiples, IV pit = intervessel pit, VP pits = vessel-parenchyma pits. ray width categories: 1 = 1 to 3 cells, 2 = larger rays 4-to 10-seriate, 3 = larger rays >10-seriate.  cells absent, and axial parenchyma and/or vessel elements storied (IAWA characters 31,46,77,98,110, 120 with 111 absent) occurs only in Malvaceae -in Bombacoideae (Adansonia, Bombax, Cavanillesia, Ceiba, Chiranthodendron, Pachira) and Sterculioideae (Brachychiton, Sterculia). Bands of very narrow fibers  and intervessel pits (crowded alternate and) polygonal (Table 1) support affinity with Bombacoideae. Ceiba, particularly C. pentandra (L.) Gaertn., shares the most characters with the fossil. this is a genus of ~20 species with an exclusively New World distribution except for C. pentandra, which has a range extending to Africa. It includes small to very large, often emergent forest trees occurring in lowland dry to mesic and seasonally flooded forests (Gentry 1993;Wittmann et al. 2010). the genus, like most Bombacoideae, shows variability in abundance of axial parenchyma and presence/ absence of parenchyma bands and marginal parenchyma based on study of material in wood slide collections (Aw).  and  do not describe tile cells for Bombacaceae/Bombacoideae, and most descriptions of Ceiba do not include tile cells; however, some material (e.g., Chorisia -now Ceiba) in the wood slides collections consulted (Aw) appear to have tile cells. Similarities to C. pentandra include rays commonly fused vertically, parenchyma and fiber bands 1 cell wide, and frequent uniseriate rays; one difference is that C. pentandra has crystals in axial parenchyma and rays (richter & Dallwitz 2000-onward;InsideWood 2004-onwards). Cavanillesia is also similar but has a higher proportion of axial parenchyma relative to fibers/wide parenchyma bands (Richter & Dallwitz 2000-onwards;InsideWood 2004-onwards). the other Bombacoid taxa listed above differ mainly in that they lack parenchyma with two cells per strand; most species of Pachira also have silica bodies in rays and crystals (InsideWood 2004-onwards). Some species of Sterculia (Sterculioideae) are also similar but this subfamily generally has wider rays; also when vessel-ray parenchyma pits are enlarged, as in some Sterculia, they generally have reduced borders. the combination of vessel-ray parenchyma pits with much reduced borders to apparently simple, diffuse-in-aggregates parenchyma, and rays with sheath cells (IAWA characters 300, 77, and 110) does not occur in any fossil wood referred to Malvaceae in the InsideWood database. there are few records of fossil bombacoid woods in the Neotropics, where the subfamily is thought to have originated . the fossil is referred to a new species of Ceiba based on its correspondence to the genus, particularly C. pentandra. Woodcock,Meyer et Prado,sp. nov. (Fig. 2) Diagnosis: Wood with growth rings, diffuse porous. Vessels solitary and in short radial multiples, mean tangential diameter 100-150 µm, perforations simple; intervessel pits alternate; vessel-ray parenchyma pits variable within individual cells, simple, similar in size to intervessel pits to enlarged. Fibers non-septate. Axial parenchyma scanty paratracheal to vasicentric, diffuse-in-aggregates to banded, and in marginal bands. rays non-storied, 1-9-seriate with procumbent body ray cells, sheath cells, and 1-4 rows of marginal cells. Axial parenchyma, vessel elements, and fibers storied. Etymology: the species is named for the Huancabamba-Amotape Biogeographic Zone in southern Ecuador and northern Peru.
Affinity. In the InsideWood database, the combination of large intervessel pits, parenchyma diffuse-in-aggregates and marginal, larger rays 4-10-seriate, sheath cells, and axial parenchyma and/or vessel elements storied (IAWA characters 27,77,89,98,110,120) occurs only in Malvaceae -Bombacoideae [Adansonia, Ceiba, Chorisia (now Ceiba)]. Other features supporting affinity with Bombacoideae within Malvaceae are reduced border vessel-ray parenchyma pits, non-storied rays, and absence of tile cells (table 1;  . Intervessel pits that are crowded alternate and polygonal and medium to large and bands of fibers that are narrow relative to the associated apotracheal parenchyma    (photos in InsideWood 2004-onwards;Acevedo & Kikata 1994) like the fossil but with crystals in rays and/or axial parenchyma. Adansonia also shares many characters but has wider vessels and axial parenchyma strands 4-8 cells long. the fossil differs from the previous wood type (C. archeopentandra) in having narrower, more densely arranged vessels, larger pits, axial parenchyma primarily in strands of 4, lower rays, wide bands of marginal parenchyma, and dark contents in vessels. the fossil is referred to a new species of Ceiba based on characters shared with this genus.

Ochroma pozoensis
Etymology: The specific epithet refers to the Pozo embayment, a marine incursion in northern Peru during the later Eocene.
Type locality: Piedra Chamana Fossil Forest main site, Sexi, Peru, associated with the volcanic flow deposits.
Affinity. Presence of tile cells is a strong indication of Malvaceae. In the InsideWood database, the combination of vessels ≤ 5/mm 2 , axial parenchyma in strands of 2-4, wider rays 4-10-seriate, rays >1 mm high, tile cells, and wood non-storied (IAWA characters 46,91,92,98,102,(111)(112)(113)(114)(115)(116)(117)(118)(119)(120)(121)(122) occurs only in Ochroma. Other shared characters are tile cells >2x higher than procumbent cells (Pterospermum type) and vertically fused rays (richter & Dallwitz 2000-onwards). Ochroma is variable with respect to proportion of axial parenchyma and fiber length richter & Dallwitz 2000-onwards;InsideWood 2004-onwards), but the fossil has vessels that are narrow relative to the genus and the appearance of the tile cells (round rather than rectangular in tangential view) differs from most material seen. Pith made up of thin-walled spongy tissue has been noted for Bombacoideae (Metcalfe & Chalk 1950). Ochroma, with one accepted species (O. pyramidale (Cav. ex Lam.) Urb.), has affinities with Bombacaceae/Malvoideae (Duarte et al. 2011;Marinho et al. 2014). Some key wood-anatomical characters are shared with Bombacoideae, which have medium-large intervessel pits and include taxa with wide, sparsely distributed vessels and tile cells (rare in Malvoideae), but there are also differences (absence of storied parenchyma, Table 1). Long vessel tails and wide fibers, characters seen in the fossil, have also been noted as distinguishing Ochroma from Bombacaceae in New World taxa . Ochroma pyramidale occurs in early successional lowland to montane wet tropical forests on rich soil, from southern Mexico and Central America into South America, and within the Amazon basin is more common on the western margins (Pennington et al. 2004;GBIF 2001-onwards).
No fossil wood shows a close correspondence to the fossil specimen and none to our knowledge has been described as having similarity to Ochroma.
Based on characters shared with Ochroma pyramidale, the fossil is named to a new species within the genus.

Guazuma santacruzensis
Etymology: the species epithet refers to the province of Santa Cruz, which includes the district of Sexi and the fossil forest.
Affinity. In the InsideWood database, the combination of diffuse porous wood, small intervessel pits; rays 4-10-seriate, >1 mm, with tile cells, and lacking sheath cells; and low rays storied (IAWA characters 5, 25, 98, 102, 111, 119 with 110 absent) occurs only in Malvaceae -in Byttnerioideae (Guazuma) and Grewioideae (Grewia, Luehea, Microcos). these subfamilies are considered sister groups (Alverson et al. 1999). Guazuma, particularly G. ulmifolia Lamb., is most similar to the fossil, sharing most coded characters and additionally having Intermediate type tile cells, uniseriate rays infrequent and anatomically similar to wider rays, and rays generally without distinct marginal cells; however, G. ulmifolia has crystals not seen in the fossil. Guazuma is a New World genus with three species occurring in early successional dry to mesic and seasonally flooded forests (Gentry 1993;Kubitzki 1989). Other similar taxa in Grewioideae (Luehea) differ in having rays frequently uniseriate and with marginal cells.
Of the fossil woods referred to Malvaceae, Guazumaoxylon rodríguez-reyes, Falcon-Lang, Gasson, Collinson & Jaramillo, with type species G. miocenica from the Miocene of Mexico, has Intermediate-type tile cells but differs from the fossil in having smaller pits, aliform paratracheal parenchyma, and rays that are narrower and non-storied.
Based on similarity to the Neotropical genus Guazuma, particularly G. ulmifolia, the fossil is named to a new species within this genus.
Type locality: Piedra Chamana Fossil Forest main site, associated with the volcanic flow deposits.
Description: Growth rings distinct, marked by an incomplete ring of solitary vessels, changes in fiber wall thickness, and discontinuous marginal parenchyma. Wood diffuse to semi-ring porous (Fig. 5 A). Vessels solitary and in radial multiples of 2-3, occasionally 4-7 (Fig. 5A), especially in the later part of the growth ring; tangential diameter 73 ± 14 µm, frequency ~52/mm 2 , round in outline, end walls horizontal to slightly oblique with long tails, perforations simple; intervessel pits alternate, round to oval ( occurring irregularly at the growth ring boundary; in strands of 4 cells. rays 2(-3)-seriate, composed of procumbent and square to upright tile cells that are mostly 1.5 to 2 (3) times higher than the procumbent cells (Intermediate type) and broadly rectangular in radial view (Fig. 5H), with 1 (2) row(s) of high to very high upright cells at the margins; low rays often with tile cells extending across the width of ray (Fig. 5 C); tangential diameter of procumbent ray cells 10-15 µm; rays of two distinct heights, low rays 321 ± 58 µm, high rays 653 ± 82 µm; ray frequency ~6/tangential mm. rays and vessel elements storied ( Affinity. the combination of vessel multiples >4 common (even if variable) and rays 1-3-seriate and with tile cells (IAWA characters 10, 97, 111 present with 98 and 99 absent) does not occur in any wood included in the IAWA database. tile cells are a strong indication of Malvaceae, but this wood has several features unusual for the family. Most Malvaceous woods have axial parenchyma that is diffuse to diffuse-in-aggregates or, less commonly, in wider bands. Apotracheal parenchyma absent to sparse (apart from marginal parenchyma) is less prevalent but common in Grewioideae (InsideWood 2004-onwards). ring/semi-ring porosity and vessels commonly in multiples of 4 or more and > 40/mm 2 are likewise infrequent in the family (table 1), recorded in 42, 16, and 24, respectively, of the 341 species of Malvaceae included in the InsideWood database. the fossil displays many similarities to Grewia. this large (>300 accepted species) genus of lianas, shrubs, and generally small trees occurs in dry areas and is distributed widely in the tropics except for the New World. Grewia is variable with respect to storying, axial parenchyma, and ray characteristics; shows a tendency toward ring-or semi-ring porosity; and is the only genus in the subfamily including species with vessel frequency >40/mm 2 . Other features seen in the fossil also present in species of Grewia include diffuse or diffuse-in-aggregates apotracheal parenchyma absent (InsideWood 2004-onwards), vessels commonly in radial multiples of four or more (G. barombiensis K. Schum., InsideWood; G. multiflora Juss. H-19679 -Aw), narrow rays with tile cells extending the width of the ray (G. androyensis Capuron -InsideWood; G. asiatica L., H-24275. and G. tiliaefolia Vahl, H-8347-Aw ), and rays 1-3-seriate and with tile cells (G. androyensis Capuron, G. polygama roxb., G. thouvenontii Danguy, G. villosa Willd. -InsideWood 2004-onwards) -the latter an unusual combination in Malvaceae. tile cells in Grewia range from Intermediate to Pterospermum type and are broadly to narrowly rectangular (InsideWood 2004-onwards, Aw). Most species in the InsideWood database also have low rays and lack rays >1 mm. the fossil wood Grewinium (Bande & Srivastava) Srivastava & Guleria, with type species Grewinium intertrappeum (Shallom) Srivastava & Guleria from the Deccan traps, was established for woods with similarity to Grewia. the fossil shows some correspondence to the genus but has narrow, storied rays. Woods, mainly from South Central Asia but also the Neogene of Europe, referred to Grewinium (Gregory et al. 2009), have tile cells and rays that are generally wide (4-10-seriate) and >1 mm high but vary in presence of growth rings and marginal parenchyma, porosity, pit size, presence/type of axial parenchyma, presence of crystals, storying, and presence of radial canals (G. canalisum, InsideWood 2004-onwards). the fossil appears atypical relative to these woods in having vessels commonly in radial multiples ≥ 4 and 40-100/mm 2 and narrow rays that are storied and not >1 mm.

Grewinium
Affinity. Tile cells establish the affinity of the fossil with Malvaceae, although radial canals are rare in this family. the only genus with this combination of characters in the InsideWood database is Luehea (Malvaceae -Grewioideae), but this New World genus and related genera (Microcos subclade of Grewioideae) differ from the fossil in having prevalent uniseriate rays and rays that are narrower and with some degree of storying. Apeiba (also Grewioideae) has also been noted as having radial canals (Wheeler et al. 2017).
the fossil wood Grewinium (Grewioxylon) canalisum (Bande & Srivastava) Srivastava & Guleria (reviewed/rephotographed in Wheeler et al. 2017) from the Deccan traps of India has Pterospermum type tile cells and radial canals and is similar to the fossil specimen in most respects, although having wider vessels; it is the only species referred to the genus that has radial canals. the Deccan fossils date from the latest Cretaceous-early Paleogene, when the Indian subcontinent had not yet rafted out of the Southern Hemisphere. Wheeler et al. (2017) consider G. canalisum to have a clear affinity with Grewioideae. Supporting this placement are the generally sparse apotracheal parenchyma and aliform-winged paratracheal parenchyma and vessel frequency >40/mm 2 seen in the Peru fossil; these features are rare in Malvaceae but occur in some Grewioideae (Grewia, Mollia).
In consideration of the close similarity to the fossil wood Grewinium canalisum, we refer the fossil to this taxon. Establishment of a new genus for fossil woods with tile cells and radial canals, as mentioned by Wheeler et al. (2017), appears warranted, especially considering the absence of radial canals in modern Grewia species.
Luehea Willd. Woodcock,Meyer et Prado,sp. nov. (Fig. 7) Diagnosis: Growth rings distinct, wood diffuse to semi-ring porous. Vessels solitary and in short to long radial multiples, mean tangential diameter 100-150 µm, perforations simple, intervessel pits alternate, vessel-ray parenchyma pits similar to intervessel pits. Fibers non-septate. Axial parenchyma scanty paratracheal and sparsely diffuse to diffuse-in-aggregates. rays storied, 1-2-seriate, wider rays with procumbent body ray cells, tile cells of the Intermediate type and narrowly rectangular, and one row of marginal square to upright cells.

Affinity. Presence of tile cells is a strong indication of affinity with Malvaceae.
In the InsideWood database, intervessel pits small to medium only, and rays >1 mm high with tile cells and some degree of storying (IAWA characters 25,26,102,and 111 with 118 or 119 also present) occurs only in the subfamily Grewioideae (Colona, Grewia, Luehea, Lueheopsis). the occurrence of sparse to absent axial parenchyma in this subfamily has already been noted. Luehea appears to be most similar to the fossil specimen. this genus is diffuse to semi-ring porous and variably storied, generally has uniseriate rays prevalent, and includes taxa with vessels in occasional long radial multiples (L.  Sonsin et al. 2014, L. speciosa, InsideWood 2004 as in the fossil. One difference is that Luehea generally has wider rays and crystals. this genus (and others in the subfamily) generally has dark contents in rays and often also discrete dark globules/ oil bodies. Oil bodies, while not commonly seen in prepared plant material because of the solutions used, can often be found intact in fresh tissues (Lersten et al. 2006) -and possibly, as here, in permineralized material. Luehea (16 species) is a New World genus of deciduous to semi-deciduous/brevi-deciduous trees occurring in Central and South American seasonal to seasonally flooded forests (Gentry 1993;Wittmann et al. 2006). Grewia, although also showing a tendency toward ring or semi ring porosity and long vessel multiples, generally has rays < 1 mm and is less storied; tile cells appear to be Intermediate to Pterospermum type. the fossil wood Tilioxylon lueheaformis Crawley (Crawley 2001), from the Pliocene of Britain, was named for its similarity to Luehea (formerly in tiliaceae). Although sharing many characters with the fossil, including tile cells apparently of the Intermediate type and absence of elaborate paratracheal parenchyma, T. lueheaformis has vessels primarily in multiples and rays wider and non-storied. Crawley (2001) notes that this form genus (Tilioxylon Burgh) and Grewioxylon have been used for Malvaceous woods with vessels in long radial multiples, diffuse to diffuse-in-aggregates parenchyma, and rays with tile cells; however, the type species of Tilioxylon (T. palaeocordatum Burgh) has homocellular rays lacking tile cells (Crawley 2001).
the fossil is most similar to New World Luehea and related taxa within Grewioideae and is named to a species within this genus.
VasiVaea Baill. Woodcock, Meyer et Prado, sp. nov. (Fig. 8) Diagnosis: Growth rings present, wood diffuse to semi-ring porous. Vessels solitary and in short radial multiples, mean tangential diameter 50-100 µm, perforations simple, intervessel pits alternate, vessel-ray parenchyma pits similar to intervessel pits. Fibers non-septate. Axial parenchyma scanty paratracheal and diffuse to diffuse-in-aggregates. rays non-storied, 1-4-seriate, composed of procumbent body ray cells, Intermediate type tile cells, and one row of marginal upright cells or with long uniseriate extensions. Vessel elements, fibers, and axial parenchyma irregularly storied. Etymology: the fossil is named for Maximilian Weigend, for his contributions to the floristics and ecology of northern Peru.
Affinity. In the InsideWood database, vessels 50-100 µm, diffuse-in-aggregates parenchyma, axial parenchyma in strands of 4, and rays not >1 mm and with tile cells (IAWA characters 41, 77, 92, 111 with 90 and 102 absent) occurs only in Dombeyoideae (Dombeya) and Grewioideae (Grewia, Luehea, Vasivaea). Vasivaea appears to be most similar to the fossil. this genus has frequent low to high uniseriate rays, multiseriate rays with uniseriate extensions, abundant apotracheal parenchyma, and rays with tile and sheath cells (Uw30522, InsideWood 2004-onwards). tile cells appear to be of the Intermediate type (although no radial section was available for reference). Other similar genera (Luehea, Grewia) lack the abundant apotracheal parenchyma seen in the fossil; Luehea also has rays >1 mm. Vasivaea is a New World genus with two species occurring in Amazonian and Colombian Inter-Andean riparian/seasonally flooded lowland forests (Pennington et al. 2004).
It appears that no fossil wood has been described showing a close correspondence to the fossil.
the fossil is most similar to extant Vasivaea (Grewioideae) and is named to a new species within this genus. Woodcock, Meyer et Prado, sp. nov. (Fig. 9) Diagnosis: Growth rings indistinct or absent, wood diffuse porous. Vessels solitary and in short radial multiples, mean tangential diameter 150-200 µm, intervessel pits alternate, vessel-ray parenchyma pits similar to intervessel pits but somewhat larger or enlarged with reduced borders. Fibers non-septate. Axial parenchyma vasicentric and diffuse-in-aggregates. rays non-storied, 1-12-seriate, composed of low procumbent body ray cells, sheath cells, and 2-4 marginal rows of square to upright or tall procumbent cells. Axial parenchyma and vasicentric tracheids storied.

Sterculia matrum
Etymology: The specific epithet refers to the women of the Club de Madres, a civic organization in Sexi that has supported our scientific work.
Among fossil woods, Sterculinium Guleria shares key features with the fossil (storied axial parenchyma, wide rays with sheath cells and lacking tile cells) but has widely banded parenchyma. the large number of woods referred to this genus, mostly from the tertiary of Central South Asia, include S. shapurensis (Bande & Prakash) Guleria and S. deccanensis (Lakhanpal, Prakash & Bande) Guleria, which have diffuse-inaggregates/narrowly banded parenchyma like the fossil but differ in having vessel-ray parenchyma pits similar to intervessel pits. the Sterculinium woods appear to show a general correspondence to Chattaway's Old World grouping within Sterculia, characterized by (mostly) widely banded parenchyma and ray-axial parenchyma pits similar to intervessel pits. the fossil is most similar to New World Sterculia species with diffuse-in-aggregates parenchyma and ray-parenchyma pits variably enlarged/with reduced borders, and is named to a new species within the genus. Miconioidea Woodcock, Meyer et Prado, gen. nov. Woodcock,Meyer et Prado,sp. nov. (Fig. 10) Diagnosis: Growth rings distinct to indistinct, wood diffuse porous. Vessels solitary and in short radial multiples, mean tangential diameter 50-100 µm, intervessel and vessel-ray parenchyma pits bordered, alternate. Fibers mostly non-septate and with occasional septae, dimorphic with parenchyma-like fibers in irregular bands. Axial parenchyma scanty paratracheal. rays uniseriate, rarely biseriate or with short biseriate portions, of all upright cells or including some procumbent and weakly procumbent cells.

Miconioidea eocenica
Etymology: the genus name refers to similarity of the fossil to woods in the subfamily Miconieae of Melastomataceae. the species name refers to the age of the fossil assemblage.
Holotype: USM-S61 (diameter 6 cm). Type locality: Piedra Chamana Fossil Forest main site, Sexi, Peru, associated with the volcanic flow deposits. Description: Growth rings distinct to indistinct, marked by radially flattened fibers and changes in vessel frequency (Fig. 10 A). Wood diffuse porous. Vessels crowded, solitary and in radial multiples of 2-4, also often in contact tangentially, with horizontal to oblique end walls, tangential diameter 81 ± 19 µm, frequency 59/ mm 2 , perforations simple; intervessel pits alternate, round to oval (Fig. 10 E), ~5 µm; vessel-ray parenchyma pits bordered, similar to intervessel pits (Fig. 10D); vessel element length 361 ± 62 µm. Vessels with thin-walled tyloses (Fig. 10 B). Fibers mostly non-septate, but some with thin septae, very thin-to thick-walled, dimorphic, consisting of narrow fibers and wider and shorter fibers that are parenchyma-like and occur diffusely and in irregular tangential bands (Fig. 10B, H); pitting not observed. Axial parenchyma scanty paratracheal, in strands of 4 or more cells long with tapered ends. rays uniseriate (Fig. 10 G), rarely biseriate or with short biseriate portions, 1-2 to 20 cells high, of all upright cells or with occasional rows of procumbent to weakly procumbent cells occurring away from the margins (Fig. 10 C, F), height 261 ± 95 µm, frequency ~8/ tangential mm. Vessels occasionally with light-colored contents; ray parenchyma with dark contents at the cell periphery.
the only fossil wood referred to the Melastomataceae, Memecyloxylon germanicum Gottwald, differs from this specimen in having included phloem, much sparser vessels, and multiseriate rays (InsideWood 2004-onwards).
In the case of this specimen, comparisons to modern woods are constrained by the most similar modern taxa being highly diverse, in some cases questionably monophyletic, and including many shrubs and small trees typically not well represented in databases. Consequently, although correspondence to an extant taxon cannot be ruled out, the fossil is named to a new genus and species showing affinity to Melastomataceae -Miconieae.

Muntingia solipora
Etymology: the fossil is named after the predominantly solitary vessels seen in the wood.
Affinity. In the InsideWood database, vessels solitary and 100-200 µm in diameter, axial parenchyma in strands of 2-4, and vessels and axial parenchyma storied (IAWA features 9, 42, 91, 92, 120) occurs only in Muntingia (Muntingiaceae). the specimen shares with this genus the characters of densely pitted vasicentric tracheids, uniseriate rays frequent, multiseriate rays with occasional sheath cells, rhomboidal crystals in ray cells, and vertically fused rays (Carlquist 2005); however, rays are high for the genus (Carlquist 2005;InsideWood 2004-onwards). the monotypic genus Muntingia (M. calabura L.) is a small evergreen tree distributed from Central America into the northern Andes and western Amazon basin as an element of secondary vegetation (Gentry 1993). the related genus Discraspidia differs from the fossil in several respects (narrower denser vessels, all multiseriate rays, non-storied wood; Carlquist 2005). Balanites (Zygophyllaceae) also shares many characters with the fossil but differs in having patterned vessel arrangement, axial parenchyma fusiform and in strands of 2, and wider rays (InsideWood 2004-onwards).
No fossil wood displays the characters seen in the fossil specimen.
The closest affinity appears to be with Muntingia calabura and the fossil is named to a new species within this genus.  Woodcock,Meyer et Prado,sp. nov. (Fig. 12) Diagnosis: Wood with distinct growth rings, diffuse porous. Vessels solitary and in short to long radial multiples, mean tangential diameter ≤ 50 µm, perforations simple, intervesssel pits alternate, vessel-ray parenchyma pits similar to intervessel pits. rays 1-4-seriate; multiseriate rays composed of procumbent cells, 1-7 rows of upright to square marginal cells, and occasional sheath cells.

Calycophyllum plengei
Etymology: the fossil is named for Heinz Plenge, photographer and conservationist.
Affinity. the combination of vessels commonly in radial multiples ≥ 4, ≤ 50 µm in diameter, and ≥ 100 /mm 2 ; very thick-walled fibers; and rays 1-4-seriate with > 4 rows of upright to square marginal cells (IAWA characters 10,40,50,70,98,108) occurs only in Phyllanthaceae (Cleistanthus), rubiaceae (Calycophyllum, Rondeletia) and Salicaceae (Casearia). the specimen shares the most characters with Calycophyllum, particularly C. candidissimum Vahl. Narrow, crowded vessels (although not to the extent seen in the fossil? ), minute to small intervessel pits, vessel-ray parenchyma pits similar to intervessel pits, narrow rays with long uniseriate margins, sheath cells in wider ways, and absence of storying are typical of rubiaceae; perforated ray cells are noted as widespread in the family (Jansen et al. 2002). Frequent uniseriate rays of all upright/square cells are also typical (InsideWood 2004-onwards). the fossil lacks rays >1 mm, a feature common in the family but not present in Calycophyllum (Inside-Wood 2004-onwards). Most features of the fossil are within the range of variability of Calycophyllum; perforated ray cells have been noted for C. candidissimum and other species in the genus (Chalk & Chattaway 1933;León 2011;Baldin et al. 2016). Similar taxa in Salicaceae (Casearia) and Phyllanthaceae (Cleistanthus) generally have rays >1 mm (InsideWood 2004-onwards). Calycophyllum is a New World genus of 11 species of trees occurring in successional forests on alluvial soil, including flooded forests (C. spruceanum, Kubitzki 1989). the genus has vessels that are narrow and densely arranged relative to most tropical forest canopy trees. Calycophyllum species that are deciduous and occur in drier forests (C. candidissimum, C. multiflorum Griseb.) have vessels < 50 µm in diameter and >150/mm 2 , whereas evergreen C. spruceanum (Benth.) Hook. f. ex K. Sch., a taller tree occurring in Amazon lowland forests, has vessels 50-100 µm and 50-150/mm 2 . the fossil is within the range of the deciduous taxa.
No fossil wood referred to rubiaceae has the combination of narrow vessels in radial multiples >4 like the fossil and we are unaware of any wood described as having affinity with Calycophyllum.
the wood is named to a species of Calycophyllum based on its similarity to this genus, particularly C. candidissimum. Woodcock,Meyer et Prado,sp. nov. (Fig. 13) Diagnosis: Wood with distinct growth rings, diffuse porous. Vessels solitary and in short radial multiples, mean tangential diameter 50-100 µm; perforations simple; intervessel pits alternate, vessel-ray parenchyma pits similar to intervessel pits. Fibers non-septate. Parenchyma scanty paratracheal to vasicentric. rays non-storied, 1-4-seriate, composed of procumbent cells and 1-6 rows of square to upright marginal cells. rhomboidal crystals in rays.

Zanthoxylum reynelii
Etymology: the fossil is named for Carlos reynel, for his contributions to Neotropical botany.
New World species of Zanthoxylum are tropical to temperate in occurrence and are most diverse on the eastern slopes of the Andes and in areas peripheral to the Amazon basin in successional to mature forests (reynel 1995, 2017). they are medium sized to occasionally tall forest trees, small trees, and shrubs and are mostly deciduous.
Among fossil woods, Fagaroxylon Burgh, named for its similarity to temperate-latitude Fagaria (now subsumed in Zanthoxylum), shares with the fossil the characters of vessels solitary and in short radial multiples, simple perforations, alternate pitting, scanty paratracheal parenchyma, and heterocellular rays. Included taxa Fagaroxylon atkinsoniae Crawley, F. bavaricum Selmeier, and F. limburgense Burgh (all from the Miocene of Europe) have marginal parenchyma like the fossil but differ in having crystals in axial parenchyma and not rays; F. bavaricum also differs in its homocellular rays.
Although showing similarities to woods in the fossil genus Fagaroxylon, closer correspondence to extant New World Zanthoxylum based on a range of characters leads us to name the fossil to a species within this genus. Woodcock,Meyer et Prado,sp. nov. (Fig. 14) Diagnosis: Wood with distinct growth rings, diffuse to semi-ring porous. Vessels solitary and in radial multiples of 2-3, mean tangential diameter 50-100 µm, perforations simple, intervessel pits alternate, vessel-ray parenchyma pits similar to intervessel pits. Fibers non-septate. Axial parenchyma paratracheal scanty, irregularly aliform, and marginal. rays (1-)2(-3)-seriate; composed of weakly procumbent cells or with 1-3+ rows of marginal square or upright cells or procumbent and square cells mixed throughout.

Dodonaea piedra-chamana
Etymology: the fossil is named for the fossil forest Piedra Chamana ("Stones of Chamana"). Chamana is the local name for Dodonaea viscosa, which is abundant at the site.
Affinity. the combination of small intervessel pits; vessels 50-100 µm and 40-100/ mm 2 ; fibers with simple to minutely bordered pits and very thick-walled; rays 1-3-seriate of all procumbent cells, and wood non-storied (IAWA characters 25 104 with 98 and 118-122 absent) occurs only in Combretaceae (Terminalia), rutaceae (Helietta, Limonia, Murraya), and Sapindaceae (Dodonaea, Pappea). the fossil shares most characters with taxa in the Dodonaeoideae subfamily of Sapindaceae. Diffuse porous wood, vessels solitary and in short radial multiples with simple perforations, deposits in vessels, small intervessel pits, vessel ray pits similar to intervessel pits, scanty paratracheal parenchyma, predominantly uniseriate or predominantly biseriate rays, and wood non-storied are typical of Sapindaceae (Klaassen 1999). rays are described as typically homocellular or weakly heterocellular, i. e., having squarish cells in a discontinuous row(s) at the margins or mixed throughout (Klaassen 1999). Fibers can be septate, non-septate, or mixed (Klaassen 1999). Crystals generally occur in axial parenchyma but were not seen in the fossil. the combination of vessel frequency 40-100/mm 2 , non-septate fibers, and rays 1-3-seriate is unusual in Sapindaceae, occurring only in temperate-latitude Acer and Dodonaeoideae (Dodonaea, Exotheca, Hippobromus, Hypelate). Of the latter, Exotheca and Hypelate are New World taxa and Dodonaea is a large genus (~70 species) occurring mainly in Australia but including D. viscosa, which is distributed worldwide in the tropics and subtropics. these taxa are shrubs to small trees occurring in drier areas and as elements of strand or littoral vegetation. Dodonaea is most similar to the fossil. this genus has higher rays than most taxa in the subfamily (Klaassen 1999). Crystals in axial chains are conspicuously present in almost all Dodonaeoideae but can be absent or rare in D. viscosa (H-8833, H-25517, H-16408 -Aw; and material from Hawaii in collection of first author). Vessel elements are short for Dodonaea (Lui & Noshiro 2003), although quite short in D. viscosa from Florida (rock 1972) and in general often shorter in juvenile wood (Carlquist 1988). the features of the fossil are encompassed within the variability seen in D. viscosa, which has axial parenchyma scanty paratracheal and variably winged-aliform to confluent and marginal, rays mainly uniseriate to 2-4-seriate, growth rings and crystals present to absent, and fibers occasionally septate (Meylan & Butterfield 1978;Li et al. 1995;Klaassen 1999;Lui & Noshiro 2003). Dark contents in ray cell periphery and extending into cell walls are evident in Dodonaea (InsideWood 2004-onwards) but also occur in other Sapindaceae.
the fossil shares some features with Sapindoxylon Kräusel from the the Miocene of Asia, but Sapindoxylon has predominantly uniseriate rays. We are unaware of any fossil woods described as having similarity to Dodonaea.
Based on correspondence to Dodonaea and taxa in Sapindaceae -Dodonaeoideae, the fossil is named to a new species within the genus. DISCUSSION AND CONCLUSIONS these descriptions add to those published previously (Woodcock et al. 2017) and allow for discussion of the floristics and paleoecology of the assemblage, which includes 31 taxa of non-monocot angiosperms (table 2).
Avicennia sexiensis Woodcock, Meyer et Prado occurs widely at the site and dominates the leaf impression flora. The mangrove genus Avicennia occurs in coastal mangrove, mixed freshwater, and riverine mangrove forests throughout the tropics; it often dominates where conditions are hypersaline. Avicennia germinans (L.) L., which this wood type most resembles, is the most widely occurring mangrove in the New World and also the most eurytopic (Saintilan et al. 2014). No other mangrove species has been recovered. the mangrove genera Rhizophora and Laguncularia frequently occur with Avicennia in New World mangrove associations, generally sorting out along gradients relating to salinity, nutrients, or innundation time. Early Paleogene mangroves were dominated by Pelliciera and the mangrove palm Nypa, but sometime after the middle Eocene these genera became more restricted in occurrence (Pelliciera) or disappeared from the New World (Nypa) and Avicennia, Rhizophora, and Laguncularia became dominant (rull 1998;Gee 2001 the co-occurrence of Avicennia leaves and trunks of non-monocot angiosperms and palms in situ in one location at the fossil site indicates that mixed freshwater mangrove forest is one of the vegetation types represented. Many of the fossil taxa are likely elements of this forest or associated seasonally flooded floodplain forests. These include: 1) Prioria (one species in Central America, adjacent areas of Colombia, and the upper Orinoco) and Vasivaea (two species in the Amazon and northern South America), both of which appear limited to flooded environments (Richards 1996;GBIF 2001-onwards); and 2) Ceiba, Cynometra, Hura, Ochroma, cf. Pseudomonotes, and Thiloa, all of which include species that are locally dominant (hyperdominant) or have their main occurrence in seasonally flooded New World tropical forests (ter Steege et al. 2006).
Floristically, the assemblage has similarities with the várzea forests of the western, Andean slopes of the Amazon basin and the northern Andes in Colombia and Venezuela. these forests are developed on rich alluvial soils associated with white water river systems and are distinct floristically from the forests of the Central Amazon and Guiana shield. Calycophyllum, Ceiba, Cordia, Guazuma, Hura, Luehea, Ochroma, and Sterculia include species considered characteristic of várzea (Kubitzki 1989). the abundance of Malvales (11 out of 31 wood types) -particularly Malvaceae but also including Muntingia (Muntingiaceae) and cf. Pseudomonotes (Dipterocarpaceae)may relate to the adaptations of Malvalean taxa to seasonally flooded, alluvial, and disturbed environments. Malvaceae are especially well represented in (high-water) low várzea in present-day South American forests (Wittmann et al. 2010), and the Malvalean genera Guazuma, Ochroma, and Muntingia are closely associated with ruderal environments and early successional forests. trees of the várzea are generally evergreen and can be quite large-statured, especially on upper terraces experiencing shorter flooded periods (high várzea, Wittmann et al. 2010). Of the represented taxa, Cariniana, Ceiba, and Cynometra species are generally large emergent trees. A 0.75 m diameter specimen of Cynometra is the largest fossil tree at the site. these three fossil taxa all have vessel diameters in the range 150-180 µm, consistent with their being tall trees.
Although the fossils predate the main period of Andean uplift at ~13 Ma, early phases of the Andean orogeny in Peru's western cordillera date to the Middle to Late Eocene  and could have produced fluvial-dominated environments of the type indicated here. Instability of the volcanic sediments upon which the vegetation was developed may also be a factor influencing the early-successional aspect of the assemblage. Marine incursions in western Amazonia during the Paleogene include the Pozo embayment, which extended from Colombia to northern Peru during the Eocene (roddaz et al. 2010). the paleovegetation may have been similar to that in northern Venezuela where broadleaf evergreen and deciduous forests including Anacardium, Cariniana, Ceiba, and Hura intergrade with mangroves (Conde & Alarcón 1993).
The majority of tree species in the flooded forests of the South American tropics extend into adjacent interfluvial/terra firme forests or are generalists occurring in a range of forest types (Wittmann et al. 2010). Several of the likely floodplain forest elements -Calycophyllum, Cariniana, Ceiba, Cynometra, Guazuma, Luehea -are also well represented or occur typically in dry or seasonal forests. And those taxa with modern representatives restricted to terra firme vegetation -Anacardium, Dalbergia, Cordia (3 wood types), Grewia, Zanthoxylum, Dodonaea -are also most prevalent in drier areas (Useful tropical Plants Database, Gentry 1993). Occurrence of ringor semi-ring-porous woods (Dalbergia, Cordia -3 wood types, and Lagerstroemia -2 wood types), a functional type not well represented in present-day tropical forests (Boura & De Franceschi 2007), also points toward an interfluvial vegetation that was dry deciduous to semi-deciduous forest and in addition suggests a strongly seasonal precipitation regime that may have had no close analog in present-day South America.
The majority of the woods have affinities to New World taxa or groups, but discordant elements include 1) an anacardiaceous wood showing closest affinity to Mangifera, an Old World taxon; 2) three species of Lythraceae referred to Lagerstroemia, likewise an Old World genus; and 3) woods in Malvaceae -Grewioideae including one wood very similar to the Old World genus Grewia and an apparently extinct species (Grewinium canalisum) very similar to a Deccan traps wood from the Cretaceous-Paleocene boundary. Mention might also be made of the wood type allied to the only dipterocarp in the South American flora (Pseudomonotes) and a basal clade (Monotoideae) occurring in Africa; this record may be part of the ultimate vicariance story if the dipterocarps, with an apparent Gondwana origin, rafted north with the Indian subcontinent to become the dominant trees of the Southeast Asia tropical forests (Ashton 2014).
In summary, the fossils of the Piedra Chamana Fossil Forest document the vegetation growing in coastal to near-coastal location in South America at 39 Ma and the existence of vegetation types including coastal mangrove, mixed mangrove forest with Avicennia, diverse seasonally flooded freshwater forest with floristic similarities to modern várzea, and deciduous to semideciduous interfluvial non-flooded (terra firme) forest. Although the presence of taxa that are common and characteristic elements of the Neotropical flora indicates persistence over time of environments and associations, particularly seasonally flooded forest, the dry forest component of the vegetation shows a less clear correspondence to modern associations and may be especially significant as regards South American forest and climate history.