Comparative analysis of shape variation in the cone scales of Larix dahurica and L. cajanderi (Pinaceae)

Geometric morphometric analysis of shape variation in the cone scales of two closely related larch species, Larix dahurica Laws. (=Larix gmelinii (Rupr.) Rupr) and L. cajanderi Mayr, was carried out. The data on the taxonomy and distribution of L. dahurica and L. cajanderi are contradictory. The taxonomic status of L. cajanderi has been confirmed by the genetic and morphological studies performed in Russia and based on considerable evidence, but the species has not been recognized internationally, being considered as a synonym of Larix gmelinii var. gmelinii. In the systematics of larch, morphological characters of the generative organs are mainly used as diagnostic markers, among the most important being the shape variation of the cone scales. The aim of this study was to test geometric morphometrics as a tool for analyzing differentiation of L. dahurica and L. cajanderi in the shape of their cone scales. Characterization of shape variations in cone scales using geometric morphometric methods consists in digitizing points along an outline of scales followed by analysis of partial warps, describing individual differences in coordinates of the outline points. We studied the populations of L. dahurica from Evenkia and the Trans-Baikal region and six L. cajanderi populations from Yakutia and Magadan Oblast. In each population, we analyzed samples of 100-150 cones collected from 20-30 trees. Scales taken from the middle part of the cones were scanned using an Epson Perfection V500 Photo. On the scanned images, outline points were placed with a TPSDig program (Rolf, 2010), using angular algorithm (Oreshkova et al., 2015). The data were processed and analyzed using Integrated Morphometrics Programs (IMP) software (http://www.canisius.edu/~sheets/ morphsoft.html, Sheets, 2001), following the guidelines on geometric morphometrics in biology (Pavlinov, Mikeshina, 2002; Zelditch et al., 2004). Initial coordinates of the scale landmarks were aligned with the mean structure for L. dahurica and L. cajanderi cone scales using Procrustes superimposition in the CoordGen6 program. PCA based on covariances of partial warp scores was applied to reveal directions of variation in the shape of the cone scales. The relative deformations of the cone scales (PCA scores) were used as shape variables for statistical comparisons of these two larch species with canonical discriminant analysis. Morphotypes of the cone scales were distinguished in L. dahurica populations by pairwise comparison of samples from trees in the TwoGroup6h program using Bootstrap resampling-based Goodall’s F-test (Sheets, 2001). Samples from the trees in which the cone scales differed significantly (p < 0.01) were considered to belong to different morphotypes. Morphotypes distinguished in L. dahurica populations were compared with the morphotypes that we had previously determined in L. cajanderi populations. The composition and the frequency of occurrence of morphotypes were used to determine phenotypic distances between populations (Zhivotovskii, 1991). Multidimensional scaling matrix of the phenotypic distances was applied for ordination of larch populations. In this research, we revealed differentiation of L. dahurica and L. cajanderi using geometric morphometric analysis of the shape variation of cone scales. The results of PCA of partial warp scores exposed four principal components, which account for 90% of total explained variance in the shape of the cone scales in the two larch species. Graphical representations of these shape transformations in the vector form characterized directions of shape variability in scales corresponding to the maximum and minimum values of four principal components (See Fig. 2). PCA-ordination of the larch populations revealed some difference in the shape variation of the cone scales in L. dahurica and L. cajanderi (See Fig. 3). The results of canonical discriminant analysis of relative deformations of scales showed differentiation of the populations of the two larch species (See Fig. 4). Eleven morphotypes were identified in L. dahurica cones from Evenkia and nine morphotypes in the Ingoda population, three of the morphotypes being common for both populations (See Fig. 5). The shape of L. dahurica cone scales varied from spatulate to oval and their apical margins from weakly sinuate to distinctly sinuate. The Trans-Baikal population was dominated by scales with obtuse (truncate) and rounded apexes. The obtained morphotypes were compared with 25 cone scale morphotypes previously distinguished in the Yakut and the Magadan L. cajanderi populations (See Fig. 3). Four similar morphotypes of cone scales were revealed in the North-Yeniseisk population of L. dahurica and the Yakut populations of L. cajanderi. The differences between them in the populations of the two larch species were nonsignificant (p > 0.01). All morphotypes of cone scales from the Ingoda population of L. dahurica differed significantly from L. cajanderi cone scale morphotypes. The results of multidimensional scaling phenotypic distance matrix calculated based on the similarity of morphotypes of L. dahurica and L. cajanderi populations were consistent with the results of their differentiation based on relative deformations of scales obtained using canonical discriminant analysis (See Fig. 4 and Fig. 7). In spite of the differences in the shape of the cone scales between the North-Yeniseisk and the Trans-Baikal populations of L. dahurica, they both differed from L. cajanderi populations. Thus, phenotypic analysis confirmed differentiation of these two larch species. Despite the similarities between a number of morphotypes, the Yakut L. cajanderi populations were differentiated from L. dahurica populations. Significant differences were noted between intraspecific groups: between L. cajanderi populations from Okhotsk-Kolyma Upland and Yakutia and between L. dahurica populations from Evenkia and the Trans-Baikal region (See Fig. 4). The similarities between species and intraspecific differences may be attributed to the ongoing processes of hybridization and species formation in the region where the ranges of the larches overlap with the ranges of L. czekanowskii Szafer and L. dahurica×L. cajanderi hybrids. Geometric morphometrics can be used as an effective tool for analyzing differentiation of L. dahurica and L. cajanderi in the shape of their cone scales.

A new specimen of Araucaria fricii from the early Coniacian of the Bohemian Massif, Central Europe

A specimen of Araucaria fricii is described from the upper part of the Teplice Formation in the Bohemian Cretaceous Basin. It extends the first occurrence of A. fricii from the mid-Coniacian back to the early Coniacian. Found in the Radovesice locality near Kučlín in the northern part of the Czech Republic, it is characterised by a deltoid cone scale complex with a centrally placed seed. It is compared to the type material of A. fricii from the mid-Coniacian Březno Formation and other European Cretaceous species of Araucaria. The taphonomy and palaeoecology of A. fricii is briefly discussed.

Stutzeliastrobus Bohemicus Comb. Nov. – Basal Cupressaceae Conife from the Cenomanian of the Bohemian Cretaceous Basin, Central Europe

The Cupressaceae conifer Stutzeliastrobus bohemicus (Bayer) J.Kvaček comb. nov. is described from the Cenomanian Peruc-Korycany Formation of the Bohemian Cretaceous Basin. It is characterised by elongate ovuliferous cones with helically arranged thin, bilaterally symmetrical ovuliferous bract-scale complexes, bearing two to four winged elongate ovoid seeds per bract-scale complex. Ovuliferous cones are found attached to twigs of Cyparissidium-type shoots, showing amphistomatic scale-like leaves with an adaxial cuticle, bearing two stomatal bands with transversely or obliquely orientated monocyclic to amphicyclic stomata. The abaxial cuticle shows monocyclic to amphicyclic stomata scattered irregularly in the basal part of the leaf. The lectotype is compressed, but the 3D preserved lignified specimen, studied using X-ray microtomography, revealed its internal structure. It is compared to Stutzeliastrobus foliatus F.Herrera et al. from the Early Cretaceous of Mongolia, differing in morphology of its bract-scale complexes. The thin ovuliferous cone scales complexes of S. bohemicus bearing two to four winged seeds per cone scale argue for its relationship with Taiwanioideae, the basal subfamily of Cupressaceae.

Understanding the cone scale in Cupressaceae: insights from seed-cone teratology in Glyptostrobus pensilis

Both wild-type and teratological seed cones are described in the monoecious conifer Glyptostrobus pensilis and compared with those of other Cupressaceae sensu lato and other conifers. Some Cupressaceae apparently possess a proliferation of axillary structures in their cone scales. In our interpretation, in Glyptostrobus each bract of both typical and atypical seed cones bears two descending accessory shoots, interpreted here as seed scales (ovuliferous scales). The primary seed scale is fertile and forms the ovules, the second is sterile and forms characteristic tooth-like structures. The bract and the two axillary seed scales are each supplied with a single distinct vascular bundle that enters the cone axis as a separate strand; this vasculature also characterises the descending accessory short shoots in the vegetative parts of the crown. In wild-type seed cones, the fertile seed scale is reduced to its ovules, and the ovules are always axillary. In contrast, the ovules of some of the teratological seed cones examined were located at the centre of the cone scale. An additional tissue found on the upper surface of the sterile lower seed scale is here interpreted as the axis of the fertile seed scale. Thus, the central position of the ovules can be explained by recaulescent fusion of the upper fertile and lower sterile seed scales. In several teratological cone scales, the ovules were enveloped by an additional sterile tissue that is uniseriate and represents an epidermal outgrowth of the fertile seed scale. Close to the ovules, the epidermis was detached from lower tissue and surrounded the ovule completely, except at the micropyle. These teratological features are potentially significant in understanding seed-cone homologies among extant conifers.

Phylogenetics of extant and fossil Pinaceae: methods for increasing topological stability

Relationships of living and fossil Pinaceae were inferred using parsimony and Bayesian inference of morphological characters and plastid and nuclear DNA sequences. When considering extant taxa only, adding molecular to morphological characters resulted in markedly increased resolution and branch support compared with analysis of morphology alone. Including 45 fossil taxa resulted in drastically decreased resolution in morphology-based consensus trees. We evaluated the effect on branch support and resolution of including DNA sequences, deleting fossils lacking information for cone scale apices and seeds, using reduced consensus methods, and using implied weighting, and found that the greatest improvements were found by including DNA sequences and using implied weighting. The tree topologies from parsimony and Bayesian inference confirm previous findings that the fossil genus Pseudoaraucaria and a few species of Pityostrobus from the Lower Cretaceous are related to abietoid genera, and that other species of Pityostrobus are pinoid and closely related to Pinus. Focusing phylogenetic analyses on the most complete fossil cones, specifically those that are anatomically preserved and include both cone scale apices and seeds, and taking into account homoplasy, resulted in the clearest hypotheses for the timing and sequence of diversification in the family.

Biogeography of Pleistocene conifer species from the Ziegler Reservoir fossil site, Snowmass Village, Colorado

Pleistocene biogeography of conifer species is poorly known in much of western North America. We conducted morphological studies on 201 conifer cones and cone fragments recovered from Pleistocene sediments at the Ziegler Reservoir fossil site (2705 m) near Snowmass Village, Colorado. The basin, formed ~155–130 ka, contains fossil-bearing lacustrine, palustrine, and colluvial sediments spanning approximately 85 ka. Using a suite of morphological characters, particularly cone-scale bracts, we differentiated species of Abies, Picea, and Pseudotsuga. All fossil Abies specimens were assignable based on bract morphology to Abies concolor, which is currently absent from central Colorado (nearest populations are 160 km southwest of the site). A. concolor occurs only in sediments of MIS 5d and 5c. Pseudotsuga menziesii and Picea engelmannii cones occurred in sediments corresponding to MIS 5e, 5d, 5c, and 5a. A fourth conifer species, occurring in sediments of MIS 5e, 5d, 5c, and 5a, is difficult to assign to any extant species. Bract morphology is similar to Picea pungens, which grows near the site today, but scale morphology is unlike P. pungens. These fossils may represent ancestral P. pungens, an extinct variant, or an extinct sister species.

Composition of Essential Oil from Seeds and Cones of Abies Alba

The volatile composition of Abies alba Mill. seeds and cone scales has been studied, leading to the determination of 90 volatile constituents. The major component of the seed essential oil was (-)-limonene (about 70%), while that of the cone scale oil was α-pinene (57%). Monoterpene hydrocarbons were predominant in both oils, but the quantitative and qualitative composition of the volatile compounds was specific for each part of the tree.