Manilkaroxylon sp.

Koutecký, Vít & Sakala, Jakub, 2015, New Fossil Woods From The Paleogene Of Doupovské Hory And České Středohoří Mts. (Bohemian Massif, Czech Republic), Acta Musei Nationalis Pragae Series B 71 (3 - 4), pp. 377-398 : 386-387

Manilkaroxylon sp.

Pl. 1, Fig. 3, Pl. 5, Fig. 1–5, Text-fig. 14–15

M a t e r i a l: Divoká rokle: DR 2.

D e s c r i p t i o n. Wood is diffuse-porous ( Text-fig. 14 ); growth rings are distinct, and 0.5–0.6 mm wide. Vessels arranged in radial pattern ( Text-fig. 14 ).

Vessels: Mostly solitary (ca. 76%) or in radial multiples of 2–3, tangential multiples of 2 and occasionally in clusters; solitary pores circular to angular in outline. Tangential diameter 35–89–147 µm, radial diameter 29–167 µm; pore density 18–34–43 per square mm. Perforation plates simple, horizontal or slightly inclined; intervessel pits alternate, with angular outlines, 6–9 µm in diameter; vessel element lengths 225– 312–500 µm.

Rays: Heterocellular, 1–3 cells (14–42 µm) wide, 1–18 cells (56–539 µm) high, body composed only of procumbent ray cells and marginal rows of upright ray cells; ray density 5–10 rays per tangential mm. Rays with long uniseriate extremities almost as wide as multiseriate portions, rays with short extremities generally spindle-shaped ( Text-fig. 15 ).

Axial parenchyma: Diffuse to diffuse-in-aggregates, and scanty paratracheal.

Fibres: Thin-walled, septate fibres present.

On the longitudinal sections, there are crystals, sometimes crossing the anatomical elements.

D i s c u s s i o n. An overall poor preservation of anatomical elements at longitudinal sections, and problematic distinction of axial parenchyma in cross section make exact determination of this wood type quite difficult. The vessel arrangement together with alternate intervessel pitting, presence of thin heterocellular rays, and prismatic crystals point to the family Sapotaceae (Wheeler et al. 2007) . The problem consists of the presence of banded parenchyma typical of Sapotaceae , which was not observed in our wood. It might be that such thin bands are present, but not distinguishable from fibres. The presence of wide bands is rather improbable, as they should be observed in radial section as well. Similarly, a presence of prismatic crystals in our wood is problematic, because they can later be obscured by permineralization.

Prakash et al. (1982) showed a great similarity and consequent difficult classification of the taxa in the family Sapotaceae . Based on InsideWood database (2004 – onwards), we compared our wood with several fossil species from Sapotaceae described as Arganioxylon sardum BIONDI , Bumelioxylon holleisii SELMEIER , Chrysophylloxylon pondicherriense AWASTHI , Madhucoxylon cacharense PRAKASH et TRIPATHI , Manilkaroxylon crystallophora GRAMBAST-FESSARD , Manilkaroxylon bohemicum PRAKASH et al. , Sapotoxylon multiporosum PRAKASH et al. , Sapotoxylon sp. 1 and Sapotoxylon sp. 2 both described by Wheeler et al. (2007) and Siderinium deomaliense PRAKASH et AWASTHI.

A. sardum has up to 8-cell-wide tangential bands of axial parenchyma, and long radial groups of vessels ( Biondi 1981b). B. holleisii is the only one with polygonal vessel outlines ( Selmeier 1991), but the author described spiral thickenings in vessels, distinctly smaller vessel diameters and thinner rays than in our wood. B. holleisii is similar to modern Bumelia , which was classified by Kukachka (1978a) into “ Bumelia A”. Ch. pondicherriense has up to 50-cellhigh rays, and very long vessel elements ( Awasthi 1975). The nearest modern living relative, genus Chrysophyllum , also has very long vessel elements, with the shortest ones (in Ch. marginatum ) having a mean length 530 µm ( Kukachka 1978b). M. cacharense does not have vessels arranged in radial multiples ( Prakash and Tripathi 1975). S. multiporosum has higher (up to three times higher) pore density than our wood, and maximally biseriate rays ( Prakash et al. 1982). Sapotoxylon sp. 1 and sp. 2 are similar to our wood, but they have wider bands of axial parenchyma (Wheeler et al. 2007). S. deomaliense has very high rays, up to 77 cells ( Prakash and Awasthi 1969). Our wood shows the greatest similarity to Manilkaroxylon ( Grambast-Fessard 1968) . The problem consists only in the presence of banded parenchyma, which was discussed previously. Because of similarity with Sapotaceae , our wood was also compared with modern Manilkara , the wood of which has, according to Kukachka (1981), the following features: vessels arrange-

Grewioxylon Grewioxylon Grewioxylon Grewioxylon Craigia ? – 72/03 Chattawaya Triplochitioxylon auctumnalis ortenburgense ortenburgense ortenburgense ( Sakala et al. 2010 paliformis oregonensis

( Gottwald 1997) ( Selmeier 1985) ( Selmeier 2000) (our wood) + new observation) ( Manchester 1980) ( Manchester 1979)

diffuse to semi-ring diffuse to semi-ring diffuse to semi-ring

Porosity semi-ring porous semi-ring porous semi-ring porous semi-ring porous

porous porous porous solitary; mostly solitary; mostly in

solitary; mostly in solitary; in radial

in radial multiples solitary and radial uncommonly solitary and in

s olitary and in radial radial uncommonly multiples of 2–4;

Vessel arrangement of 2–6 (inclinations in radial multiples in tangential multiples radial multiples

multiples of 2–4 in tangential occasionally

to tangential of 2–7 of 2–3 (6); rarely of 2–3 multiples of 2–3(4) in clusters

multiples) in clusters

190–235 µm 156–299 µm 140–363 µm 149–372 µm

Vessels tangential earlywood; 58–240 (280) µm earlywood; earlywood; earlywood; 20–250 µm 40–290 µm

diameter 80–115 µm latewood (early and late wood) 52–143 µm latewood 47–167 µm 56–177 µm (early and late wood) (early and late wood)

vessels vessels latewood vessels latewood vessels

6–11 per square mm 4–13 per square mm 5–11 per square mm 6–9 per square mm

in early wood; in early wood; 5–12 in early wood; in early wood; 9–10 average 14 per

Vessels density 4–9 per square mm 7–16 per square mm per square mm 8–18 per square mm per square mm square mm 1–9 per square mm in late wood in late wood in latewood in late wood

Perforation plates simple simple simple simple simple simple simple alternate, polygonal

Intervessel pits alternate alternate alternate, hexagonal unknown alternate alternate

(5–6 mm)

vasicentric (1–3 cells diffuse, vasicentric

vasicentric (locally paratracheal, diffuse, diffuse to diffuse wide sheaths) diffuse and diffuse and scanty and reticulate in

Axial parenchyma aliform); marginal occasionally in in aggregates, and reticulate in vasicentric vasicentric uniseriate tangential

(discontinuous bands) discontinuous bands vasicentric uni- and biseriate aggregates

tangential aggregates uniseriate and uniseriate and 4–8 uniseriate and 4–11

uniseriate and 3–4(6) 4–8(12) cells wide (widening at growth (widening at growth 1–3 seriate and

uniseriate and 3–12 1–10 cells wide,

cells wide, hetero- (wider on growth ring boundaries) ring boundaries) 4–14 cells wide,

cells wide with tile heterocellular with

Rays cellular with tile ring boundaries), cells wide, cell wide, presence of tile

cells of Ptero- tile cells Pterosper-

cells of Pterosper- heterocellular with heterocellular with heterocellulas with cells of Ptero-

spermum type mum type

mum type tile cells of Ptero- tile cells of Ptero- tile cells of Ptero- spermum type spermum type spermum type spermum type

Rays per tg mm unknown 7–11(13) 5–9 3–4 3–6 2–6 3–7

in tile cells and

Prismatic crystals present absent absent absent absent axial parenchyma in tile cells ment into parallel radial rows, eventually in combination with clusters; vessels in short radial multiples; uni- to biseriate rays sporadically 3- to 4-seriate and one- to three-cell wide tangential bands of axial parenchyma. The presence of prismatic crystals is typical only of some of species: M. albescens and M. jaimiqui have prismatic crystals even in tyloses ( Kukachka 1981). On the basis of these features (wood diffuse porous, vessels arrangement in radial pattern, thin rays with low bodies and long extremities), our wood can be placed close to Manilkara , and designated Manilkaroxylon . Only two species were defined so far within this fossil genus: M. crystallophora and M. bohemicum . M. crystallophora ( Grambast-Fessard 1968) has smaller vessels than our wood, and its rays contain abundant prismatic crystals. M. bohemicum (Prakash et al. 1974) has markedly bigger vessels, and abundant prismatic crystals in axial parenchyma. The problem with the presence of prismatic crystals in our wood was discussed earlier. Due to poor preservation of the single specimen, we leave our wood in open nomenclature as Manilkaroxylon sp.

In the Tertiary of north-western Bohemia, no fossil remain of Manilkara or Manilkaroxylon is known.

Figures

Text-fig. 14. Schema of transversal section of Manilkaroxylon sp. (sample DR2). ap – axial parenchyma, grb – growth ring boundaries, r – rays, v – vessels.

Text-fig. 15. Schema of observed rays of Manilkaroxylon sp. (sample DR2).