DESCRIPTION AND COMPARISONS

The Holyoke Araucaria bract-scale complex is about 1.67 cm long, with only the most distal portion missing (Figure 2.1). It is 0.8 cm wide at the base and expands distally to 1.37 cm wide near the apex. A single obovate seed, which is represented by a distinct thickening in the middle of the complex surface, is enclosed by the complex tissues. On each side of the central seed-bearing zone is a 0.2 cm wide wing with longitudinal striations. The seed-bearing zone is well defined due to the presence of two deep, longitudinal grooves that delineate it from the wings. The distal part of the complex shows a distinct thickening that is concave toward the base. No ligule (free portion of the ovuliferous scale) is visible, but this is probably due to preservational factors. The basal part of the complex shows three lobes; the central lobe is produced by the base of the seed-bearing region, and the smaller lateral lobes are formed from the bases of the wings.

The new Araucaria bract-scale complex is most similar in shape, wing morphology, and ovule disposition to those of section Eutacta of Araucaria. Among extant species, it is particularly similar to those of Araucaria heterophylla (Figure 2.2). In comparison, bract-scale complexes of section Araucaria (= Columbea) have a nut-like shape and entirely lack wings, and those of section Bunya have thicker woody wings, and the seed is shed from the complex. Finally, the bract-scale wings of section Intermedia are broader and thinner than those of Eutacta.

Araucaria section Eutacta has a rich fossil history, and during the Mesozoic it was present in both hemispheres (Stockey 1982; Hill and Brodribb 1999); however, most records are based on vegetative remains (Hill and Brodribb 1999). One exception is Araucarites stockeyi from the Lower Jurassic of Utah, which is suggested as a representative of section Eutacta by Tidwell and Ash (2006) based on the wedge-shaped bract-scale complex with a short apical point, and the centrally placed ovule that was apparently retained at maturity. Although this may indeed be the earliest record of section Eutacta, the wings of the Holyoke bract-scale complex described here make it an even more convincing representative. Araucarites phillipsii from the Jurassic of Yorkshire (Kendall 1949; Harris 1979; Van Konijnenburg-van Cittert and Morgans 1999) has been referred to section Eutacta based on characters of the ovuliferous cones and seedlings (Stockey 1982). Bract-scale complexes of Araucarites phillipsii are similar in shape and size to the Holyoke Araucaria; however, they do not show the clear delimitation of the seed-bearing zone, and no distal thickening has been observed. Araucarites baqueroensis and Araucarites minimus from the Cretaceous of Argentina have also been included in section Eutacta (Del Fueyo and Archangelsky 2002). The bract-scale complexes of these species are similar in general morphology to the Holyoke specimen, but Araucarites minimus is much smaller (nearly half of the size) while Araucarite baqueroensis is considerably larger. Another well-known species is Araucarites brodiei, from middle Jurassic of Oxfordshire (Cleal and Rees 2003). However, these fossils are notably larger than the Holyoke Araucaria bract-scale complex, the seed occupies the lower part of the complex rather than the middle, and no wings are present. In addition, the seed in Araucarites brodiei is born in a depression on the bract-scale but is not embedded in its tissues (Cleal and Rees 2003). In fact, this character suggests that this species may not be close to Araucaria at all, as the seeds of this genus are embedded in the tissues of the bract-scale complex at least during some ontogenetic stage. Based on these comparisons, it is proposed that the Holyoke Araucaria bract-scale complex provides enough features to be confidently assigned to Araucaria section Eutacta and represents the earliest record of this section.