Spore assemblages from the Lower Devonian Xujiachong Formation from Qujing,Yunnan, China

Abstract: The Lower Devonian Xujiachong Formation from the vicinity of Qujing City, Yunnan, China is interpreted as a terrestrial‐fluviatile‐lacustrine sequence. It contains important nonmarine biotas including plants, fish and invertebrates. The plants are particularly interesting as they include many endemic taxa. Dispersed spore assemblages have been recovered from the upper part of this formation. The spores are well preserved and of moderate thermal maturity. They are systematically described and four new species erected: Aneurospora xujiachongensis sp. nov., Chelinospora ouyangii sp. nov., Camptozonotriletes? luii sp. nov. and Leiozonospora xichongensis sp. nov. One new combination is proposed: Aneurospora conica (Ouyang and Lu) comb. nov. This is a rare report of a Lower Devonian dispersed spore assemblage from the South China Plate. Indeed, few dispersed spore assemblages of this age are known outside of Euramerica and Northern Gondwana. It is suggested that the Xujiachong Formation spore assemblages can all be equated to the polygonalis‐emsiensis Spore Assemblages Biozone (PE SAB) of Richardson and McGregor (1986) indicating an early (but not earliest) Pragian to ?earliest Emsian age. However, caution is urged, because biostratigraphical interpretation is difficult owing to distinct differences between dispersed spore assemblages from South China and Euramerica/Northern Gondwana. This almost certainly reflects palaeophytogeographical variation and regional endemism among early land plant floras on widely separated land masses. Palynofacies analysis supports a nonmarine origin for the deposits of the Xujiachong Formation, with the very rare marine palynomorphs that were encountered interpreted as reworked.     

Tetrads in sporangia and spore masses from the Upper Silurian and Lower Devonian of the Welsh Borderland

Prior to the mid-Silurian, evidence for the earliest embryophytes comes from dispersed spores, particularly permanent tetrads, there being no fossils showing gross morphology or anatomy of the producers. The fragmentary coalified mesofossils described here from the uppermost Silurian (Pridoli) and basal Devonian (Lochkovian) of the Welsh Borderland contain tetrads assigned to Tetrahedraletes, Velatitetras and Cheilotetras. These spores together with examples from spore masses have been examined by scanning and transmission electron microscopy and display diversity in ultrastructure of the exospore and envelope. Tetrads have been found, together with a putative elater, in the forking apex of an axial Lochkovian fossil, named Grisellatheca salopensis gen. et sp. nov., that anatomically, apart from spore characters, reveals no unequivocal evidence for hepatic affinity. The remaining fossils are equally as uninformative as regards affinity. Tetrads with ornamented envelopes are recorded in an isolated discoidal sporangium and in the bases of incomplete sporangia borne terminally on a bifurcating axis. Both ornament and ultrastructure suggest that the spores belong to quite distinct species within Velatitetras. Tetrahedraletes is recorded in an incomplete sporangium subtended by a forking axis, in which no cellular detail is preserved. Naked unfused tetrads also assigned to Tetrahedraletes are recorded in spore masses from both localities and again exospore ultrastructure demonstrates diversity. A final Lochkovian sporangium contains naked tetrads with sporadic Papiculate ornament and shows a unique trilayered exospore. Comparisons of exospore ultrastructure in these tetrads, which it is argued are mature and dispersed as such, provide no unequivocal evidence for affinities, be they tracheophyte or bryophyte. The bifurcating sporophytes are evidence against similarities with extant bryophytes. It is concluded that these very fragmentary fossils derive from small plants comprising relict populations of the vegetation that flourished on land in turfs through the greater part of the Ordovician and early Silurian, but that was gradually replaced by the tracheophytes.     

A RECONSIDERATION OF LIVING AND FOSSIL PYROPHACUS STEIN, 1883 (DINOPHYCEAE)1,2

Three previously described dinoflagellates (2 “varieties” and a “form”) that comprise the marine genus Pyrophacus Stein, 1883, are allocated, to 3 separate species for the first time after demonstration of appropriate discontinuities in their respective theca and cyst morphologies. Formerly they were called P. horologium Stein var. horologium, P. horologium var. steinii Schiller and, Pyrophacus Form B₁ of Steidinger and Davis; they become P. horologium Stein, P. steinii (Schiller) nov. comb., and P. vancampoae (Rossignol) nov. comb. The newly discovered cyst stage of the latter is identical with the fossil dinoflagellate Tuberculodinium vancampoae (Rossignol) Wall, whose unusual morphology is reinterpreted to include an oblate body, 4 rows of intratabular tubercules, and a uniquely located hypotractal (posterior antapical) archeopyle. The outer wall of the newly discovered benthic encysted stage of P. horologium Stein is gelatinous and agglutinating in behavior and comparable with the amorphous “Kalyptra” that constitutes the outer wall layer of several extinct Mesozoic and Danian fossil dinoflagellates.     

Isolated Megaspore Tetrads of Stauropteris burntislandica

A new type of fossil spore tetrad, Didymosporites scotti gen.et sp. nov. is described from the Dinantian and Namurian (Carboniferous)of Ireland, Scotland, and England. The spores always occur inthe form of a tetrad composed of two large (presumably fertile)and two minute (presumably abortive) spores, all with cutinizedwalls. Reasons are given for regarding these as the megasporesof the coenopterid fern Stauropteris burntislandica; their distributionindicates a far wider range in time and space than that previouslyknown for this species. Their occurrence as adhering tetradssuggests that Stauropteris burntislandica 'shed' its megasporesstill enclosed in the sporangiumIan interesting analogy withboth Lepidocarpon and the seeds of Pteridosperms.     

Vallodiscus gen. nov., a new fossil resting spore morpho-genus related to the marine diatom genus Chaetoceros (Bacillariophyceae)

A new fossil marine diatom resting spore morphogenus, Vallodiscus Suto gen. nov., is described using samples from Deep Sea Drilling Project Site 338 in the Norwegian Sea, Sites 436 and 438 in the north‐west Pacific Ocean and the onland Newport Beach Section, California. Vallodiscus is characterized by a single ring of veins along the epivalve margin and a hypovalve covered with circular depressions of several sizes with gentle elevation. The morpho‐genus bears three new species and one new combination: Vallodiscus simplexus Suto sp. nov., Vallodiscus complexus Suto sp. nov., Vallodiscus lanceolatus Suto sp. nov. and Vallodiscus chinchae (Mereschkowsky) Suto comb. nov.     

Meiotic cytokinetic apparatus in the formation of the linear spore tetrads of Conocephalum japonicum (Bryophyta)

Most bryophytes produce tetrahedral spore tetrads. However, linear spore tetrads have been reported to occur in Conocephalum japonicum (Thunb.) Grolle. In this study, the distribution of microtubules (MTs) during meiosis in C. japonicum was examined to determine the division pattern resulting in a linear tetrad. Spore mother cells in the pre-meiotic stage were cylindrical with randomly distributed cytoplasmic MTs. In the prophase-metaphase transition, spindle MTs replaced cytoplasmic MTs and a barrel-shaped spindle with two flattened poles developed. Cortical MT arrays were not detectable throughout meiosis. Although a phragmoplast appeared between sister nuclei in telophase-I, it disappeared without expanding to the parental cell wall. Metaphase-II spindles oriented parallel to the long axis of the cell and in tandem to each other resulted in a linear arrangement of telophase nuclei. Radial arrays of MTs developed from the nuclear surfaces and three phragmoplasts appeared among the four nuclei to produce four spores. Two phragmoplasts separating the paired sister nuclei appeared prior to the appearance of a phragmoplast between non-sister nuclei. The MT cycle is basically the same as that reported in meiosis of C. conicum, which produces non-linear tetrads. A morphometric study indicated that the difference in the division pattern between C. conicum and C. japonicum is due to a difference in the shape of spore mother cells. The cylindrical shape of sporocytes of C. japonicum restricts the orientation of spindles and phragmoplasts so that the four resultant spores are arranged linearly. Received: 22 April 1998 / Accepted: 15 May 1998     

Aeroallergens in northern and southern provinces of Thailand

An aeroallergen survey in two provinces, Chiangmai in the northern and Songkhla in the southern part of Thailand which are 1 500 km apart, was done in 1986 and 1987 using a rotorod sampler. The five most common pollen types and mold spores were: Chiangmai: Mold spores: Cladosporium, rust, Fusarium, Nigrospora, 1-celled spore. Pollen grains: Mimosa, wild grasses, Urticaceae, Cyperaceae, tetrad pollen. Songkhla: Mold spores: Cladosporium, rust, Nigrospora, Papularia, 1-celled spore. Pollen grains: Casuarina, Mimosa, Urticaceae, Cyperaceae, wild grass. There were definite differences in the amount and frequency of occurrences of aeroallergens between these two provinces. Furthermore, some specific pollen and mold spores, such as tetrads and Mimosa pollen, were found only in Chiangmai, and Casuarina pollen and Papularia spores only in Songkhla. These findings might be caused by the differences in geography, plantation and meteorological data.     

Two cryptospore-bearing land plants from the Lower Devonian (Lochkovian) of the Welsh Borderland

Two examples of fragmentary, coalified plant fossils with cellular preservation and in situ spores are described using scanning and transmission electron microscopy (SEM and TEM), from a Lower Devonian (Lochkovian) locality in the Welsh Borderland. A sporophyte which produced dyads of ?Cymbohilates of. horridus is unique in that stomata are numerous on the supporting axis, and are comparable with those described from contemporary vascular plant remains. The in situ dyads possess a bilayered exospore wall, with an outer exosporal envelope present over the distal faces. A fusiform sporangium, with externally smooth epidermis, contains specimens of the tetrad Velatitetras sp. Each tetrad is encompassed by a laevigate, folded, exosporal envelope of uniform thickness, which contains a layer of regular voids. Spores within the tetrads are ultrastructurally bilayered, with a complex, digitate outer margin presumably representing spore wall ornamentation. Neither the tetrads nor dyads reported in this paper are lamellate in ultrastructure. The combination of stomata, branching and dyads in the same sporophyte holds significance for the understanding of cryptospore affinities.     

INDIAN OCEAN NANNOPLANKTON. II. HOLOCOCCOLITHOPHORIDS (CALYPTROSPHAERACEAE,PRYMNESIOPHYCEAE) WITH A REVIEW OF EXTANT GENERA1

Holococcolithophorids, pyrmnesiophytes having only one type of calcareous element in their coccoliths, are delicate and not commonly recorded in recent and fossil marine floras. There are few records of these organisms from the Indian Ocean and 26 species from there are included in this report. Although the group, generally assigned to a single family, the Calyptrosphaeraceae, may contain species that are part of the life history of heterococcolith-bearing cells in other stages, so little is known of this aspect of their biology that one must continue, at the present time, to treat them as independent taxonomic entities. A key is provided for the known holococcolithophorid genera. A new genus, Gliscolithus, and three new species, Gliscolithus amitakarenae, Calyptrosphaera heimdalae, and Helladosphaera pienaarii are described. The following new combinations are proposed: Calyptrolithina fragaria (Kamptner) comb. nov., Calyptrolithina gaarderae (Borsetti et Cati) comb. nov., Calyptrolithina isselii (Borsetti et Cati) comb. nov., Calyptrolithina lafourcadii (Lecal) comb. nov., Calyptrolithina magnaghii (Borsetti et Cati) comb. nov., Calyptrolithina multipora (Gaarder) comb. nov., Calyptrolithina porritectum (Heimdal) comb. nov., Calyptrolithina wettsteinii (Kamptner) comb. nov., Calyptrolithophora catillifera (Kamptner) comb. nov., Calyptrolithophora galea (Lecal-Schlauder) comb. nov., Dactylethra pirus (Kamptner) comb. nov., Helladosphaera arethusae (Kamptner) comb. nov., Helladosphaera gracilis (Kamptner) comb. nov., Homozygosphaera strigilis (Gaarder) comb. nov. and Syracolithus schilleri (Kamptner) comb. nov. The new combination in the genus Dactylethra Gartner for the first time brings an extant species into this genus that formerly contained only fossil species. It is pointed out that the enlarged zygoliths in stomatal areas of Corisphaera and the helladoliths in stomatal regions of Helladosphaera have intergrading types and are not distinctive enough characteristics to separate these genera.     

Morphological studies on two marine colepid ciliates from Qingdao, China, Nolandia orientalis spec. nov. and Pinacocoleps similis (Kahl, 1933) comb. nov. (Ciliophora, Colepidae)

Recent studies have revealed that the “lower” marine ciliates are far more diverse than previously suspected. During a survey on the ciliate fauna in coastal waters of Qingdao, northern China, we have isolated about 30 new or poorly known taxa. In the present study two colepid species are investigated, Nolandia orientalis spec. nov. and Pinacocoleps similis (Kahl, 1933) comb. nov. (basionym: Coleps similis Kahl, 1933). Their morphology and infraciliature are documented based on living observations and silver impregnations. The new species Nolandia orientalis differs from the type species N. nolandi mainly in the structure of tier plates. The structure of the tier plates was also the basis for transferring Coleps similis Kahl, 1933 to the genus Pinacocoleps and for three further new combinations: Pinacocoleps heteracanthus (Noland, 1937) comb. nov. (basionym: Coleps heteracanthus Noland, 1937), P. spiralis (Noland, 1937) comb. nov. (basionym Coleps spiralis Noland, 1937) and Pinacocoleps arenarius (Bock, 1952) comb. nov. (basionym: Coleps arenarius Bock, 1952).     

AULACOSEIRA SKVORTZOWII SP. NOV. (BACILLARIOPHYTA), A POORLY UNDERSTOOD DIATOM FROM LAKE BAIKAL,RUSSIA1

Aulacoseira skvortzowii sp. nov. is a diatom taxon present in modern plankton assemblages and sedimentary deposits from Lake Baikal, Russia. It has been previously reported as A. islandica (O. Müll.) Simonsen, A. islandica ssp. helvetica (O. Müll.) Simonsen, a sporangial frustule of A. baicalensis (K. Meyer) Simonsen, and Aulacoseira “spore”. However, its microstructure, ecology, and ability to form true resting spores provide ample criteria to describe this diatom as Aulacoseira skvortzowii sp. nov.     

Four new species of Orbiliaceae from Yunnan, China

During the fungal survey in YongPing County, Dali area in southwest China, a total of 50 specimens of Orbiliaceae were collected. Among them, were four apparently uncommon taxa growing on bark and wood of decayed branches of undetermined broad-leaved trees lying on the moist ground. They are described here as new species: Orbilia acicularis sp. nov., O. arcospora sp. nov., O. limoniformis sp. nov., and Hyalorbilia nodulosa sp. nov. Orbilia acicularis is characterized by needle-shaped straight ascospores, O. arcospora by spores being curved like an arch, O. limoniformis according to its lemon-shaped spores, and Hyalorbilia nodulosa by the knob-like glassy processes on the marginal excipular cells, the three Orbilia species also by filiform to subulate spore bodies (SBs) in the living spores.     

Phylogenomic reconstruction illuminates the evolutionary history of freshwater to marine transition in the subfamily Haloveliinae (Hemiptera: Heteroptera: Veliidae)

Water crickets of the subfamily Haloveliinae are semi-aquatic bugs occurring in freshwater and marine habitats throughout the Indo-Australian region, presently including six genera with more than 80 extant species. Whether lineage diversification in Haloveliinae is associated with the utilization of new ecological niches caused by transition events between freshwater and marine habitats remains poorly understood. We investigate the evolutionary history of Haloveliinae using large-scale phylogenomic datasets and a set of novel redefined morphological characters based on 24 ingroup taxa representing all recognized genera. Our phylogenetic results based on the novel datasets definitively indicate that the freshwater genus Strongylovelia Esaki as currently defined is paraphyletic and supports the establishment of a new genus: Metavelia gen. nov., including three congeneric species: Metavelia patiooni comb. nov. (type species), Metavelia priori comb. nov. and Metavelia albicolli comb. nov. Reconstruction of ancestral habitats suggests a freshwater origin for the Haloveliinae. Divergence time estimations reveal that the origin of the monophyletic marine clade occurred at around 83 Ma (95% highest posterior density: 71–98 Ma) in the Late Cretaceous, involving a single transition event from freshwater to marine habitats. This time coincides with the period of high global sea levels in the Late Cretaceous. During this period, the marine incursions caused by the massive sea level rise flooded the continental margins, especially in Southeast Asia, where ancestral Haloveliinae were probably distributed. The appearance of new marine habitats after the marine incursions (e.g., intertidal, mangroves and estuarine) probably led to a subsequent establishment and diversification of the marine lineages.     

Detection of Concealed “Illegitimate” Nuclei in Tetrad Analysis of the Diploid Progeny of Heterokaryons in Saccharomyces cerevisiae

In this work, the studies on the previously detected phenomenon of concealed heterokaryosis in Saccharomyces cerevisiaewere continued. In genetic and Southern blotting experiments, one of the nuclei in the heterokaryon was shown to be active (capable of division and ensuring the corresponding cell phenotype), whereas the other was not expressed until the heterokaryotic clone was transferred to the medium selective for this concealed nucleus. Moreover, the concealed nucleus was able to assume the active state after fusion with the second parental nucleus. It was analyzed whether the nuclei with new marker combinations occurring in meiosis can behave as exceptional nuclei. Tetrad analysis of hybrids carrying the kar1mutation in their nuclei revealed the relatively high percentage of exceptional tetrads (more than 10%). One spore in these tetrads usually formed diploid cells capable of sporulation. The presented data of genetic and molecular biological studies testify in favor of the assumption that abnormal spores contain two nuclei, which form an illegitimate hybrid after fusion. An extraneous nucleus (termed x) has usually a genotype close to that of one of the spores in this tetrad. Thus, it was assumed that the additional DNA replication round occurs in the absence of cell division during one of meiotic divisions. Results of cytological analysis conducted by the method of specific DNA staining confirmed the existence of exceptional tetrads, one spore of which contains two nuclei.     

Deux fougères fertiles du Stéphanien du Massif Central (France)

Two fertile ferns from the Stephanian of the Massif Central (France) are described in detail. One has been found in the Blanzy basin and is assigned to Oligocarpia (Sphenopteris) leptophylla (Bunbury) nov. comb., according to the morphology of the sterile pinnae and of the fructifications. Its spores agree with the «sporae dispersae Granulatisporites parvus (Ibr.) Potonié and Kremp. The other fern has been collected in the St Etienne basin and is assigned to Senftenbergia plumosa (Artis) Radforth var. ligerensis nov. var. Its spores agree with the morphographic genus Raistrickia (S., W. and B.) Potonié and Kremp but do not look like any described species; therefore the new species name R. polymorpha nov. sp. has been given to that spore.     

Trioza hopeae sp. nov. (Hemiptera: Triozidae): A pest on Hopea odorata (Malvales: Dipterocarpaceae) in Vietnam

Trioza hopeae sp. nov. is described and illustrated from Vietnam. Trioza hopeae develops on Hopea odorata, a valuable timber tree on which it causes serious damage by inducing leaf galls. The new species is closely related to Trioza minuta (Mathur) comb. nov. (from Ceropsylla Riley), an Indian species associated with Shorea robusta. Differences between the two species are discussed. Another five Indian species are transferred here from Ceropsylla to Trioza Foerster as T. ferruginea ( Mathur, 1975 ) comb. nov., T. fulvida ( Mathur, 1975 ) comb. nov., T. indica ( Kandasamy, 1986 ) comb. nov., T. longivenata ( Kandasamy, 1986 ) comb. nov., and T. parvus ( Kandasamy, 1986 ) comb. nov.     

TETRAXYLOPTERIS SCHMIDTII: ITS FERTILE PARTS AND ITS RELATIONSHIPS WITHIN THE ANEUROPHYTALES

The fertile branching system of Tetraxylopteris is composed of successive “nodes” bearing opposite and decussately arranged, upcurved sporangial complexes. By means of the transfer technique the morphology of the sporangial complex was revealed. It consists of a main stalk which dichotomizes twice producing four major branches. Each of the four branches is further subdivided three times, the subdivisions being arranged alternately and pinnately. The ultimate divisions bear the sporangia singly and terminally. The sporangial complexes decrease in size distally and are more tightly curved at the apex. The sporangia are oblong-oval with an acute apex. The spores are identical to the dispersed spore taxon Rhabdosporites langii, Richardson. They are spherical, trilete and pseudosaccate with a fine granular ornament on the pseudosaccus. They are 75–176 μ in diameter and show developmental stages from young tetrads to separated, fully mature spores depending on the age of the sporangium from which they were obtained. This is the first account of spores in sporangia of Tetraxylopteris. The diagnosis of the genus and species are emended to include the new information and the order Aneurophytales is redefined.