PALEOZOIC LYCOPSID FRUCTIFICATIONS. III. CONSPECIFICITY OF BRITISH AND NORTH AMERICAN LEPIDOSTROBUS PETRIFACTIONS

A study was made of 30 apparently similar microsporangiate cone specimens of the lycopsid fructification Lepidostrobus found in coal balls of Middle Pennsylvanian age from Illinois and Kansas. None of these specimens was a complete cone, but at least 19 were large enough and well enough preserved to provide information regarding variation both within one cone and among several specimens. The data obtained substantiated the original assumption that all 30 specimens represented one species. Attempts to equate this one species with any of the similar, previously described North American taxa, Lepidostrobus coulteri, L. pulvinatus and Lepidocarpon magnificum-microsporangiate form, and the British taxon Lepidostrobus oldhamius, including the forms (α), (β), (γ) and pilosus, revealed that no significant differences existed among any of these taxa. Furthermore, all characteristics described for these taxa were referable to, and well within the range of variation of, the one species here analyzed. Differences among the taxa were found to represent only differences in maturation or normal variation. All these taxa are, therefore, conspecific and are assigned to one species which by priority is named Lepidostrobus oldhamius. The common association of the megasporangiate Lepidocarpon lomaxi with all these miorosporangiate cones, now recognized as representing the single taxon Lepidostrobus oldhamius, is strong evidence for the probability that Lepidocarpon lomaxi and Lepidostrobus oldhamius were produced by the same parent plant species.     

PALEOZOIC LYCOPSID FRUCTIFICATIONS. I. LEPIDOCARPON PETRIFACTIONS

A reinvestigation of the 4 American species of Lepidocarpon described from petrifactions and of Illiniocarpon cadyi, also described from petrifactions, shows that they are all conspecific. When they, in turn, are compared with specimens of the British petrifaction L. lomaxi, no significant differences can be demonstrated. The criteria cited as diagnostic for the American petrifaction species of Lepidocarpon were found to fail as bases of discrimination when 400 specimens of Lepidocarpon found in coal balls of Pennsylvanian age were studied. Measurements and observations made of a sample size of 136 of these 400 specimens reveal a degree of variation compatible with that of a single species. All previously described American and British petrifaction taxa fall within (or not significantly beyond) this range of variability of a single species as determined from this sample. Additional evidence concerning the 3-dimensional sporophyll structure of this one species of Lepidocarpon and the configurations obtained by certain planes of section through it have served to demonstrate that Illiniocarpon cadyi is in reality a taxon based on sectioned structures of the sporophyll of this Lepidocarpon species. Under the rules of priority, this species of Lepidocarpon and the following are assigned to Lepidocarpon lomaxi: Illiniocarpon cadyi, Lepidocarpon ioense, L. magnificum (megasporangiate form), L. crenatum and L. palmerensis. On the basis of the morphological evidence, the British petrifaction described as Lepidocarpon wildianum is also equated with L. lomaxi.     

ACHLAMYDOCARPON VARIUS COMB. NOV.: MORPHOLOGY AND REPRODUCTIVE BIOLOGY

Structurally preserved arborescent lycopsid fructifications are described from Pennsylvanian age strata in eastern Kentucky and southern Illinois. Achlamydocarpon varius comb. nov. is the name proposed for these cones and previously reported isolated megasporophylls described as Lepidostrobophyllum varius. The specimens range up to 3.5 cm long and represent cone apices. Megasporophylls are spirally arranged and attached to the cone axis at an acute angle. Megasporangia are large with a wall two cell layers thick. Each sporangium contains one large, presumably functional megaspore, and three smaller, abortive megaspores. Functional and abortive spores possess a prominent apical tuft (massa) that covers up to one-third of the proximal surface of the spore. Sporoderm ultrastructure is detailed together with a comparison of morphologically similar sporae dispersae megaspores. The possible function of the megaspore massa is discussed as it relates to the reproductive biology of the cone.     

The Middle Devonian lycopsid Haskinsia Grierson et Banks from the Ruppert Coast, Marie Byrd Land, West Antarctica

New observations on leaves of herbaceous lycopsid specimens previously attributed to Drepanophycus schopfii Mildenhall from Marie Byrd Land, West Antarctica, indicate that they belong to Haskinsia colophylla Grierson et Banks. Haskinsia was a wide spread lycopsid during the Middle Devonian.     

Evolution and speciation in Pellia,with special reference to the Pellia megaspora-endiviifolia complex (Metzgeriales), I. Taxonomy and distribution

Abstract

The genus Pellia, with three currently recognised species, includes a relatively primitive taxon, P. endiviifolia, in which the perichaetium is high and incised, with an enclosed calyptra. It is dioecious, produces anthocyanin wall pigments in exposed sites, reproduces asexually by repeatedly furcate, narrow fragmenting ‘autumnal innovations’, is freely branched and has relatively small spores. A species previously confused with this taxon, and here described as P. megaspora, is an endemic boreal American species, found from New York, Connecticut and Massachusetts north to Newfoundland and west to Minnesota. The plant has a tall perichaetium that is strikingly incised-ciliate to lacerate. It is dioecious but does not produce wall pigments and autumnal innovations, is simple or oncefurcate and has extremely large spores. Cytological and biochemical data support the specific recognition of P. megaspora. Biochemical data also suggest that Japanese populations currently assigned to P. endiviifolia are distinct and field observation suggests that these plants may represent an autonomous subspecies.     

A Revised Systematic Ichnotaxonomy and Review of the Vertebrate Footprint Ichnofamily Chirotheriidae from the British Triassic

Since 1838, many discoveries of the tetrapod footprint taxon Chirotherium and closely similar forms have been reported from the British Middle Triassic. These have been assigned to dozens of ichnotaxa, so that the identification and interpretation of members of the ichnofamily Chirotheriidae have become confused.

Part 1 of this article deals with ichnotaxonomy. Revision of all the available material shows that there are at least three valid ichnospecies of Chirotherium, one of Synaptichnium, and one of Isochirotherium. The presence of a fourth related ichnogenus, Brachychirotherium, cannot yet be confirmed in Britain. Emended diagnoses are proposed for all four ichnogenera; they may be readily distinguished by the shape of the hand (manus) and foot (pes) impression and especially by the phalangeal counts. The natural cast of a probable tail impression, associated with Chirotheriidae footprints from the British Triassic is figured for the first time, as is a rare detailed impression of skin and the tarsal region of an Isochirotherium lomasi pes cast.

Part 2 provides a critical history of the earliest discoveries of each of these ichnogenera in the British Triassic. It is subdivided into divisions, depending on the quality of data and existence of specimens, the localities in Britain which have yielded these ichnogenera; a detailed history and discussion is provided of the earliest discoveries made at each locality. The stratigraphic distribution and paleological significance of the ichnogenera/species are assessed.     

STRUCTURE AND AFFINITIES OF PROTOSTIGMARIA EGGERTIANA

Investigation of new, more or less complete specimens of Protostigmaria eggertiana reveals that it is a large, multilobed rooting structure produced at the base of a small arborescent lycopod. The trunk bears scars marking the point of attachment of leaves, and can be compared to the stem of Lepidodendropsis. In the largest specimens the root-bearing base is divided into about 13 lobes. In smaller, presumably younger specimens, fewer lobes are present. The roots are arranged on the lobes in series and orthostichies comparable to those of Isoetes. New observations on five- and six-lobed Isoetes plants reveal a closer correspondence between Protostigmaria and Isoetes than previously recognized; and support suspected homologies among many fossil and extant lycopsid rooting structures.     

EMBRYOGENY AND REPRODUCTIVE BIOLOGY OF BOTHRODENDROSTROBUS MUNDUS (LYCOPSIDA)

Permineralized lycopsid megagametophytes and embryos from Upper Carboniferous strata (Westphalian A) at Burnley, England have been found within isolated megaspores assignable to Setosisporites. The specimens illustrate for the first time the reproductive biology and embryogeny of a free-sporing, bisporangiate, Paleozoic lycopod, and permit reinterpretation of the megagametophyte of Bothrodendrostrobus. Megagametophyte development is entirely endosporal. Embryogeny is comparable to that of the extant genus Isoetes, and is fundamentally different from that of the fossil lycopsid, Lepidocarpon—Lepidophloios. This further illustrates the diversity among Paleozoic lycopods and helps to clarify relationships among both fossil and extant lycopsid taxa.     

Recent genus Notonecta (Insecta: Heteroptera: Notonectidae) in the Lower Cretaceous of San Luis,Argentina: Palaeoecological implications

We describe a new species of the genus Notonecta, i.e. Notonecta mazzoniae n. sp. from the Lower Cretaceous of Argentina. It is the first fossil representative of the family described from South America, demonstrating the great antiquity of the genus, bearing identical ventral chaetal system correlated with respiratory for such a long period. The new species is recorded only by immature stages from the second to the fifth instars. Specimens are considered to be exuviae and not body fossils. Absence of body fossils may be due to taphonomic bias instead of palaeoecological constrains. In addition we found some specimens of Anisopinae, also considered as nymph exuviae, which represent the oldest record of the taxon.     

Phylogenomic analysis of pseudocryptic diversity reveals the new genus Deltalsia (Rhodomelaceae,Rhodophyta)

Molecular analyses, in combination with morphological studies, provide invaluable tools for delineating red algal taxa. However, molecular datasets are incomplete and taxonomic revisions are often required once additional species or populations are sequenced. The small red alga Conferva parasitica was described from the British Isles in 1762 and then reported from other parts of Europe. Conferva parasitica was traditionally included in the genus Pterosiphonia (type species P. cloiophylla in Schmitz and Falkenberg 1897), based on its morphological characters, and later transferred to Symphyocladia and finally to Symphyocladiella using molecular data from an Iberian specimen. However, although morphological differences have been observed between specimens of Symphyocladiella parasitica from northern and southern Europe they have yet to be investigated in a phylogenetic context. In this study, we collected specimens from both regions, studied their morphology and analyzed rbcL and cox1 DNA sequences. We determined the phylogenetic position of a British specimen using a phylogenomic approach based on mitochondrial and plastid genomes. Northern and southern European populations attributed to S. parasitica represent different species. Symphyocladiella arecina sp. nov. is proposed for specimens from southern Europe, but British specimens were resolved as a distant sister lineage to the morphologically distinctive Amplisiphonia, so we propose the new genus Deltalsia for this species. Our study highlights the relevance of using materials collected close to the type localities for taxonomic reassessments, and showcases the utility of genome-based phylogenies for resolving classification issues in the red algae.     

Taxonomic rearrangement of the genus Ulkenia sensu lato based on morphology, chemotaxonomical characteristics, and 18S rRNA gene phylogeny (Thraustochytriaceae, Labyrinthulomycetes): emendation for Ulkenia and erection of Botryochytrium, Parietichytrium, and Sicyoidochytrium gen. nov.

The genus Ulkenia is characterized by the naked protoplast stage within its life cycle. However, the 18S rRNA gene tree clearly shows that this genus is not a natural taxon, because our own isolates and reported strains separately form four well-supported monophyletic groups. These four groups are clearly distinguishable by their profiles of polyunsaturated fatty acids and carotenoid pigments and cell and colony morphology, e.g., persistence of sporangial wall, manner of the cell cleavage at the zoospore formation, and development of the ectoplasmic nets. Therefore, the four groups are assigned to four genera including three new genera, i.e., Ulkenia sensu stricto, Botryochytrium, Parietichytrium, and Sicyoidochytrium gen. nov.     

OBSERVATIONS ON NITELLA ACUMINATA FROM SOUTHWESTERN UNITED STATES AND NORTHERN MEXICO1

Morphological and cytological analyses of several specimens of the genus Nitella suggest that species described as N. stellaris, N. lindheimeri, N. gollmeriana, and N. mexicana and some forms reported as N. acuminata var. subglomerata represent a single taxon in the N. acuminata species group. Cytological examination revealed a chromosome number of n = 9 in the specimens from the study area but N. acuminata is known to display n = 18 chromosomes in other regions of North America and on oilier continents. Hypotheses regarding the origin and significance of this polyploidy are discussed. The habitats supporting N. acuminata (n = 9) in the study area show some features which are in contrast to those of habitats supporting the species (n = 18) in other areas of North America.     

Katian (Upper Ordovician) conodonts from Wales

Middle and upper Katian conodonts were previously known in the British Isles from relatively small collections obtained from a few localities. The present study is mainly based on 17 samples containing more than 17 000 conodont elements from an approximately 14‐m‐thick succession of the Sholeshook Limestone Formation in a road cut near Whitland, South Wales, that yielded a diverse fauna of more than 40 taxa. It is dominated by representatives of Amorphognathus, Aphelognathus/Plectodina and Eocarniodus along with several coniform taxa. Representatives of Decoriconus, Istorinus and Sagittodontina are reported from the Ordovician of UK for the first time. The fauna is a typical representative of the British Province of the Atlantic Realm and includes a mixture of taxa of North American, Baltoscandic and Mediterranean affinities along with pandemic species. Based on the presence of many elements of Amorphognathus ordovicicus and some morphologically advanced specimens of Amorphognathus superbus, the Sholeshook Limestone Formation is referred to the lower A. ordovicicus Zone. Most of the unit is also coeval with Zone 2 of the Cautleyan Stage in the British regional stage classification, and stage slice Ka3 of the middle Katian Stage in the global stratigraphical classification, an age assignment consistent with data from trilobites, graptolites and chitinozoans. The unusually large collection of M elements of Amorphognathus provides insight into the complex morphological variation in this element of some Katian species of this genus. The Sholeshook conodont fauna is similar to those of the Crûg and Birdshill limestones, but differs in several respects from the slightly older ones from the Caradocian type area in the Welsh Borderland. Although having some species in common, the Sholeshook conodont fauna clearly differs from coeval Baltoscandic faunas and is even more different in composition compared with equivalent North American Midcontinent faunas.     

Lomatogonium cherukurianum sp. nov. (Gentianaceae) from Sikkim Himalaya

Populations of an unknown taxon of Lomatogonium A. Braun have been found during floristic surveys in the alpine pasture of north Sikkim, India. Comparison with morphologically similar taxa (Lomatogonium stapfii (Burkill) Harry Smith and L. longifolium Harry Smith) revealed that the new populations represent a species new to science, which is described as L. cherukurianum. Data on phenology, ecology and distribution of the new species is provided together with illustrations.     

INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: RHAMNUS MARGINATUS (RHAMNACEAE) REEXAMINED

Leaf compressions, previously assigned to Rhamnus marginatus Lesquereux, were collected from the Middle Eocene Claiborne Formation of western Kentucky and Tennessee. The leaf architecture and cuticular features of over 40 compressions were carefully examined and compared to those of many extant species of Rhamnaceae and related families as well as fossil specimens previously assigned to this taxon. This leaf type appears to belong to the Rhamnaceae, however, it conforms more closely to species of several genera in the tribe Zizypheae than to those of Rhamnus or other genera in the tribe Rhamneae. Confident assignment to any specific genus within this complex of genera cannot be made on the basis of leaf characteristics alone and would require discovery and analysis of additional vegetative and reproductive organs. Because this fossil leaf form cannot be confidently assigned to any modern genus and earlier classifications appear to be improper, this leaf type has been reassigned to the taxon Berhamniphyllum claibornense gen. et sp. nov. The transfer of this leaf form at the tribe level reaffirms the need for close examination of taxonomic determinations made by early workers.     

Spore wall ultrastructure in the early lycopsid Leclercqia (Protolepidodendrales) from the Lower Devonian of North America: Evidence for a fundamental division in the lycopsids

Documenting the morphology and ultrastructure of spores from known Silurian-Devonian plants clarifies organization and probable affinities of dispersed spores and contributes to analyses of evolutionary changes and phylogenetic relationships in early plants. In this study of fossil in situ spores from the early protolepidodendralean lycopsid Leclercqia, we identified new characters including an additional synapomorphy of the ligulate lycopsid clade. A detailed light (LM), scanning electron (SEM), and transmission electron microscope (TEM) analysis of spores from two species of Leclercqia from the Lower Devonian (Emsian) of New Brunswick, eastern Canada, L. andrewsii and L. complexa, shows both are homosporous, yielding spores belonging to the dispersed spore form taxon Acinosporites lindlarensis. Important features of wall ultrastructure include the presence of a paraexospore, peculiar exospore-derived, peg-like structures located in the gap between the outer exospore/inner paraexospore, and multilamellate regions in the interradial areas of the proximal surface. Similar interradial multilamellate regions occur in other ligulate lycopsids (fossil and extant). This character is probably a further synapomorphy for the ligulate lycopsid clade, within which heterosporous lycopods form a monophyletic group. These data suggest the ligule and interradial multilamellate region appeared prior to heterospory.     

850. MYRCEUGENIA LEPTOSPERMOIDES

Though extremely rare in British and Irish gardens, the South American genus Myrceugenia shows great horticultural potential and a number of species have entered cultivation in the last four decades, primarily through the efforts of the Royal Botanic Garden, Edinburgh. Two of the showiest of these, Myrceugenia lanceolata and Myrceugenia leptospermoides, both Chilean endemics, are discussed.     

Two new species of Kladnostrobus nov. gen. and their spores from the Pennsylvanian of the Kladno-Rakovník Basin (Bolsovian, Czech Republic)

A new lycopsid family Kladnostrobaceae is proposed, based on the type of sporangia, their attachment by a pedicel and the type of reticulate spores enclosed. All these characteristics distinguish the Kladnostrobaceae from all other lycopsid families. A new lycopsid genus Kladnostrobus nov. gen., consisting of two new species Kladnostrobus clealii nov. sp. and Kladnostrobus psendae nov. sp., is described from the Kladno-Rakovník Basin (Lower Bolsovian) of the central and western Carboniferous continental basins of the Czech Republic. Helically arranged distal laminae and pedicels are relatively primitive, suggesting that Kladnostrobus may represent a new, primitive type of lycopsid cone produced by some unknown, probably arborescent lycopsid parent plant. Spores of Kladnostrobus are about 90-100 μm in diameter, and possess reticulate sculpture. The proximal contact area of spores is laevigate. In situ spores can resemble some dispersed species of the genera Convolutispora Hoffmeister, Staplin and Malloy, Camptotriletes (Naumova) Potonié and Kremp, Reticulatisporites (Ibrahim) Neves and mainly Dictyotriletes (Naumova) Smith and Buttterworth.