A revision of the Early Carnian Trachyceratidae (Ammonoidea) of Northeastern Asia

Major morphological features of the shell are studied, and new trachyceratid genera, Boreotrachyceras gen. nov. with the type species B. omkutchanicum (Bytschkov) and Okhototrachyceras gen. nov. with the type species O. seimkanense (Bytschkov), are established based on material from the Lower Carnian of the Omolon Massif and Northern Okhotsk Region. The first record of the genus Trachyceras in the Boreal Realm allows the correlation of the omkutchanicum Zone of Northeastern Asia with the standard aon Zone.     

A revision of Malesian Austrobuxus (Picrodendraceae/Euphorbiaceae s.l. subfam. Oldfieldioideae)

The Malesian species of the predominantly New Caledonian genus Austrobuxus were revised. Three species are recognized. Austrobuxus nitidus is widespread from south Thailand to Borneo. Characteristic for this species are the very short papillae of the caruncle. The caruncle papillae are much longer in the other two, newly described species. Austrobuxus celebicus sp. nov. is endemic to Sulawesi, where it is found on ultramafic soils, and A. dentatus sp. nov. is an endemic species of western New Guinea. The former is notable for the very small fruits and the latter for the teeth‐like glands along the leaf blade margins, unique within the genus.     

A mitochondrial stratigraphy for island southeast Asia

Island Southeast Asia (ISEA) was first colonized by modern humans at least 45,000 years ago, but the extent to which the modern inhabitants trace their ancestry to the first settlers is a matter of debate. It is widely held, in both archaeology and linguistics, that they are largely descended from a second wave of dispersal, proto-Austronesian-speaking agriculturalists who originated in China and spread to Taiwan approximately 5,500 years ago. From there, they are thought to have dispersed into ISEA approximately 4,000 years ago, assimilating the indigenous populations. Here, we demonstrate that mitochondrial DNA diversity in the region is extremely high and includes a large number of indigenous clades. Only a fraction of these date back to the time of first settlement, and the majority appear to mark dispersals in the late-Pleistocene or early-Holocene epoch most likely triggered by postglacial flooding. There are much closer genetic links to Taiwan than to the mainland, but most of these probably predated the mid-Holocene "Out of Taiwan" event as traditionally envisioned. Only approximately 20% at most of modern mitochondrial DNAs in ISEA could be linked to such an event, suggesting that, if an agriculturalist migration did take place, it was demographically minor, at least with regard to the involvement of women.     

Thrips pollination of the dioecious ant plant Macaranga hullettii (Euphorbiaceae) in Southeast Asia

Discussion about thrips (Thysanoptera) as main pollinators has been controversial in the past because thrips do not fit the preconception of an effective pollinator. In this study, we present evidence for thrips pollination in the dioecious pioneer tree genus Macaranga (Euphorbiaceae). Macaranga hullettii is pollinated predominantly by one thrips species, Neoheegeria sp. (Phlaeothripidae, Thysanoptera). As a reward for pollinators, the protective floral bracteoles function as breeding sites for thrips and trichomal nectaries on the adaxial surface of the floral bracteoles provide alimentation. Flowering phenology of both staminate and pistillate trees was highly synchronized within 3-4 wk periods. In contrast to pistillate trees, staminate trees start to breed the thrips inside the developing inflorescences ～2 wk before anthesis. Breeding of Neoheegeria sp. in the laboratory indicates that the thrips development is completed within ～17 d. Thus, staminate trees offer breeding sites for one thrips generation until the onset of pollen presentation. Intraspecific pollen transfer by thrips was proved by pollen loads of thrips taken from receptive pistillate inflorescences of M. hullettii. Bagging experiments of different mesh sizes showed that seed set reached almost the level of open-pollinated flowers when exclusively tiny insects like thrips were able to enter the net bags, but no apomictic seed set occurred when no insect access was given to the flowers.     

A chloroplast genealogy of myrmecophytic Macaranga species (Euphorbiaceae) in Southeast Asia reveals hybridization, vicariance and long-distance dispersals

Macaranga (Euphorbiaceae) includes about 280 species with a palaeotropic distribution. The genus not only comprises some of the most prominent pioneer tree species in Southeast Asian lowland dipterocarp forests, it also exhibits a substantial radiation of ant-plants (myrmecophytes). Obligate ant-plant mutualisms are formed by about 30 Macaranga species and 13 ant species of the genera Crematogaster or Camponotus. To improve our understanding of the co-evolution of the ants and their host plants, we aim at reconstructing comparative organellar phylogeographies of both partners across their distributional range. Preliminary evidence indicated that chloroplast DNA introgression among closely related Macaranga species might occur. We therefore constructed a comprehensive chloroplast genealogy based on DNA sequence data from the noncoding ccmp2, ccmp6, and atpB-rbcL regions for 144 individuals from 41 Macaranga species, covering all major evolutionary lineages within the three sections that contain myrmecophytes. A total of 88 chloroplast haplotypes were identified, and grouped into a statistical parsimony network that clearly distinguished sections and well-defined subsectional groups. Within these groups, the arrangement of haplotypes followed geographical rather than taxonomical criteria. Thus, up to six chloroplast haplotypes were found within single species, and up to seven species shared a single haplotype. The spatial distribution of the chloroplast types revealed several dispersals between the Malay Peninsula and Borneo, and a deep split between Sabah and the remainder of Borneo. Our large-scale chloroplast genealogy highlights the complex history of migration, hybridization, and speciation in the myrmecophytes of the genus Macaranga. It will serve as a guideline for adequate sampling and data interpretation in phylogeographic studies of individual Macaranga species and species groups.     

A Note on Remarkable Exines in Acalyphoideae (Euphorbiaceae)

As part of an extensive study of pollen of Euphorbiaceae that combines transmission electron microscopy with scanning electron microscopy, distinctive exines are reported and documented for certain Acalyphoideae. Cheilosa and Neoscortechinia, which comprise the tribe Cheiloseae, are the only Acalyphoideae with an echinate tectum, but their apertures and exine structure do not support a relationship to Oldfieldioideae. In Ditaxis, one of the three mesocolpia is much smaller than the other two and the pollen can be easily distinguished from all other Euphorbiaceae. In SEM, the tectum of Pycnocoma appears almost complete, but in TEM the exine consists of irregular, mostly discrete tectal elements that narrow to points (=columellae) at the interface with the threadlike footlayer. The operculate grains of Alchornea and Boquillonia have exines with a poorly differentiated double layer of columellae in the mesocolpium, but nearer the endoaperture the lower tier becomes greatly elongated and appears to rest directly on the endexine. Plukenetia polyadenia has a complete tectum and a thick exine with a predominant infratectum of large, occasionally branched columellae that nearer the tectum are combined with densely spaced granules. Plukenetia penninervia has a reticulate tectum of crenate muri and short, sparse columellae. The pollen diversity in Acalyphoideae suggests that the subfamily, many tribes and even genera may not be monophyletic.     

A new species of Croton (Euphorbiaceae) widespread in Mexico

Croton rzedowskii is described, the type being from San Luis Potosí. The species ranges from San Luis Potosi westward to Zacatecas, thence southeastward to Oaxaca.     

The origin and antiquity of syphilis (treponematosis), in southeast Asia

The pausible reasons for the paucity of skeletal evidence regarding the contraversal issue on the origin and antiquity of treponematosis (syphilis) in southeast Asia, suggest a lack of thorough investigation into the skeletal biology of the several remains that were excavated. According to an estimate the skeletal remains of about 69.5 per cent (107) of the prehistoric sites were not reported and even the remaining 30.5 per cent were not thoroughly investigated for paleopathological aspects. The two recent studies of possible evidence of treponematosis during megalithic (Iron Age) period supports the Old World hypothesis that the disease was prevalent during pre-Columbian period in India.     

Functional andromonoecy in Euphorbia (Euphorbiaceae)

The occurrence of cyathia containing staminate flowers but lacking a pistillate flower was studied in 17 species of Euphorbia. Male cyathia were found in the majority of species studied (88.2%) giving functional andromonoecy. In the male cyathia, the pistillate flower is generally totally absent, but sometimes a vestigial pistillate flower with a non-functional ovary is present. The proportion of male cyathia varied at both the population and species level. The position of male cyathia within the inflorescence showed a constant pattern among species: the proportion of male cyathia decreased from the first to the last levels of the pleiochasia. In general, perennial species had significantly higher proportions of male cyathia than annual species (mean 20 and 2.3%, respectively). In annual species there was a trend for production of male cyathia only in the first level of the inflorescence, whereas in perennials production up to the fourth level of the inflorescence was usual. Functional andromonoecy is common in Euphorbia and represents a new sex segregation in the genus. The selective forces causing this secondary sex segregation in Euphorbia, such as improved pollination or increased outcrossing, are discussed.     

A new species of Phyllanthus (Euphorbiaceae) from Somalia

Phyllanthus lunifolius sp. nov., a completely prostrate dwarf shrub from limestone rocks in the coastal part of central Somalia, is described and illustrated.     

A revision of Sullivantia (Saxifragaceae)

Sullivantia (Saxifragaceae) is restricted to the United States; its species occur in very specialized habitats such as wet cliffs and moist canyon walls in scattered localities from Washington and Oregon, eastward to Wyoming, Montana, Colorado, Missouri, Iowa, Illinois, Minnesota, Wisconsin, Indiana, Ohio, and Virginia. Relationships in the genus were reevaluated using data from morphology (including the use of greenhouse-grown plants), crossability, and flavonoid chemistry. The conclusion of this study is thatSullivantia comprises four morphologically similar allopatric taxa:S. oregana, S. hapemanii var.hapemanii, S. hapemannii var.purpusii, andS. sullivantii.     

A revision of Rhynchanthera (Melastomataceae)

The neotropical genus Rhynchanthera (Melastomataceae, Microlicieae) is revised, and 15 of the 84 proposed taxa are recognized; two species are excluded from the genus. The group consists of subshrubs and shrubs with usually purple flowers in thyrsoid inflorescences of uniparous or biparous cymes. It is characterized by androecia with five antepetalous staminodia in addition to the five fertile stamens, and - in most species - dimorphism of the stamens, with one strikingly longer than the other four. The plants always are covered by at least some simple glandular hairs. The majority of the species of Rhynchanthera occur in south-central Brazil, however, the range of the genus extends from southern Mexico to Bolivia and Paraguay. All species grow in wet places in open scrub or savanna vegetation. Micromorphological features of the seeds have been investigated and support the traditional placement of Rhynchanthera in the Microlicieae where it is closest to Microlicia, Lavoisiera , and Trembleya. Two taxa are illustrated with drawings, and the distribution of all is mapped.     

A revision of Schimperella (Brachytheciaceae)

Schimperella is a small African genus related toRhynchostegium. It is characterized by noncomplanate plants with erect capsules and reduced endostomes. Two species are recognized:S. katalensis andS. rhynchostegioides. A proposed synonym ofS. rhynchostegioides, Rhynchostegium nervosum, is best placed inIsothecium, asIsothecium nervosum.