A reassessment of some Asian species of Heterophyllium (Schimp.) Kindb. (Pylaisiadelphaceae,Bryophyta)

Introduction. Heterophyllium albicans Thér., H. henryi Tixier, H. micro-alare (Broth. & Paris) Broth. and H. tonkinense (Broth. & Paris) Broth. were all either poorly known species or known only from the type collections since their inception.

Methods. Examination of the type material confirmed that the alar cell structure in these species do not conform to the generic concept of Heterophyllium (Schimp.) Kindb. The study also revealed some new features previously unreported in these species, i.e., the filamentous pseudoparaphyllia, one of the characteristic features of the genus Isopterygium Mitt.

Key Results & Conclusions. Three new combinations, Isopterygium albicans (Thér.) Y.Jia & S.He, I. micro-alare (Broth. & Paris) Y.Jia & S.He, and I. tonkinense (Broth. & Paris) Y.Jia & S.He are proposed. Heterophyllium henryi Tixier is treated as a new synonym of Brotherella henonii (Duby) M.Fleisch.     

Limnological Studies in a Tropical Man-Made Lake (Lagartijo Reservoir) Venezuela

The purpose of this study was to evaluate the present limnological conditions of Lagartijo reservoir (North central Venezuela) and to compare them with conditions reported in early studies. Lagartijo reservoir supplies an important part of the water demand for Caracas city and wide fluctuations on water volume occur annually. Relevant physical, chemical and biological data were obtained from three sampling stations between July 1990 and April 1992. The reservoir was permanently stratified with a well defined thermocline. The main tributary (Lagartijo river), with a temperature about 6° C colder than the surface temperature of the reservoir, flows through the hypolimnion producing distinct chemical and biological properties. The average of the daily integral phytoplankton photosynthesis was 1550 mg C m⁻² d⁻¹. The present annual average of the net photosynthetic activity is about 40% lower than the reported for 1970 and corresponds to an apparent decrease in phytoplankton biomass and to the reduction of the euphotic zone. Photosynthetic activity was higher for the wet season than for the dry season. Actual chlorophyll a concentration in the euphotic zone averages 4.9 μg l⁻¹. Abundance of zooplankton was significantly decreased in comparison to 1976. Mean zooplankton biomass (dry weight) for the upper 10 m layer was 596 μg l⁻¹. Copepods accounted for most of this biomass, followed by cladocerans and rotifers. For the first time, a freshwater medusa (probably Craspedacusta sowerbyi) was collected from Venezuelan waters.     

Intraspecific variation in the status of ant symbiosis on a myrmecophyte,<Emphasis Type="Italic"> Macaranga bancana,</Emphasis> between primary and secondary forests in Borneo

A tree species, Macaranga bancana , distributed in South East Asian tropics has a mutualistic relationship with specific symbiotic ant species, which defend the plant from herbivores. To examine the intraspecific variation in the status of the ant-plant symbiosis among microhabitats of different light conditions, we investigated the species composition of nesting ants and the herbivory damage on M. bancana saplings by field observations and sampling in primary and secondary forests in Sarawak. In addition, the effectiveness of non-ant (physical and chemical) defenses were estimated by feeding the larvae of a polyphagous lepidopteran with M. bancana leaves from saplings in the two types of forests. All saplings in the primary forest were colonized by two Crematogaster ant species that had been known to be the obligate symbionts of M. bancana, while in the secondary forest, about half of the saplings were occupied by several ant species that were not obligate symbionts. There was little herbivory damage on saplings colonized by the two Crematogaster symbiont ants in both forest types, while the saplings colonized by the other ant species suffered a 10–60% loss of leaf area. Larval mortality of the polyphagous lepidopteran Spodoptera litura was significantly higher when larvae fed on leaves of M. bancana saplings in the secondary forest than when fed on leaves of M. bancana saplings in the primary forest. These results suggest that the symbiosis between ants and M. bancana is looser and the non-ant-defenses are stronger in secondary forests, where light is more intense, than in primary forests.     

Leaf domatia and foliar mite abundance in broadleaf deciduous forest of north Asia

Plant morphology may be shaped, in part, by the third trophic level. Leaf domatia, minute enclosures usually in vein axils on the leaf underside, may provide the basis for protective mutualism between plants and mites. Domatia are particularly frequent among species of trees, shrubs, and vines in the temperate broadleaf deciduous forests in north Asia where they may be important in determining the distribution and abundance of mites in the forest canopy. In lowland and montane broadleaf deciduous forests at Kwangn;akung and Chumbongsan in Korea, we found that approximately half of all woody species in all forest strata, including many dominant trees, have leaf domatia. Pooling across 24 plant species at the two sites, mites occupied a mode of 60% (range 20-100%) of domatia and used them for shelter, egg-laying, and development. On average, 70% of all active mites and 85% of mite eggs on leaves were found in domatia; over three-quarters of these were potentially beneficial to their hosts. Further, mite abundance and reproduction (expressed as the proportion of mites at the egg stage) were significantly greater on leaves of species with domatia than those without domatia in both forests. Effects of domatia on mite abundance were significant only for predaceous and fungivorous mite taxa; herbivore numbers did not differ significantly between leaves of species with and without domatia. Comparable patterns in broadleaf deciduous forest in North America and other biogeographic regions suggest that the effect of leaf domatia on foliar mite abundance is general. These results are consistent with several predictions of mutualism between plants and mites, and indicate that protective mutualisms may be frequent in the temperate zone.     

The spatial pattern of soil-dwelling termites in primary and logged forest in Sabah, Malaysia

Abstract.  1. Primary and logged lowland dipterocarp forest sites were sampled for subterranean termites using soil pits located on a grid system in order to detect any patchiness in their distribution.
2. A spatial pattern in termite distributions was observed in the primary and logged sites, but the response differed between soil-feeding and non-soil-feeding termites.
3. Spatial analysis showed that soil-feeding termites were homogeneously distributed in the primary forest but significantly aggregated in the logged forest. This pattern was reversed for non-soil-feeding termites and may result from differences in resource provisioning between the two sites.
4. Gaps in termite distribution comprised a greater area than patches for both feeding groups and sites, but gaps dominated the logged site.
5. A significant association between soil-feeding and non-soil-feeding termite distributions occurred at both sites. This arose from an association between patches in the primary forest and between gaps in the logged forest.
6. Termite spatial pattern was optimally observed at a minimum extent of 64 m and lag of 2 m.
7. The spatially explicit SADIE (Spatial Analysis by Distances IndicEs) analyses were more successful than (non-spatially explicit) multivariate analysis (Canonical Correspondence Analysis) at detecting associations between termite spatial distributions and that of other biotic and abiotic variables.     

The effect of island area on body size in a primate species from the Sunda Shelf Islands

Aim  We examine the effect of island area on body dimensions in a single species of primate endemic to Southeast Asia, the long-tailed macaque ( Macaca fascicularis ). In addition, we test Allen's rule and a within-species or intraspecific equivalent of Bergmann's rule (i.e. Rensch's rule) to evaluate body size and shape evolution in this sample of insular macaques.
Location  The Sunda Shelf islands of Southeast Asia.
Methods  Body size measurements of insular macaques gathered from the literature were analysed relative to island area, latitude, maximum altitude, isolation from the mainland and other islands, and various climatic variables using linear regression.
Results  We found no statistically significant relationship between island area and body length or head length in our sample of insular long-tailed macaques. Tail length correlated negatively with island area. Head length and body length exhibited increases corresponding to increasing latitude, a finding seemingly consistent with the expression of Bergmann's rule within a single species. These variables, however, were not correlated with temperature, indicating that Bergmann's rule is not in effect. Tail length was not correlated with either temperature or increasing latitude, contrary to that predicted by Allen's rule.
Main conclusions  The island rule dictating that body size will covary with island area does not apply to this particular species of primate. Our study is consistent with results presented in the literature by demonstrating that skull and body length in insular long-tailed macaques do not, strictly speaking, conform to Rensch's rule. Unlike previous studies, however, our findings suggest that tail-length variation in insular macaques does not support Allen's rule.     

Evolution of the eastern Asian-North American biogeographic disjunctions in ferns and lycophytes

This paper reviews 31 groups in ferns and lycophytes hypothesized to show eastern Asian–North American disjunctions. Fourteen lineages have been supported by recent phylogenetic evidence: Lycopodium nikoense and Lycopodium sitchense; Isoëtes asiatica and the clade of the North American species complex closely allied to I. maritima; Osmundastrum cinnamomeum; Osmunda claytoniana; the Adiantum pedatum complex; the Cryptogramma acrostichoides complex; Diplaziopsidaceae; Cystopteris chinensis and the Cystopteris bulbifera clade; Asplenium rhizophyllum and Asplenium ruprechtii; diploid Phegopteris; Onoclea sensibilis; the Polypodium appalachianum clade; and the Polypodium glycyrrhiza clade. Phylogenetic and/or cytological evidence did not support the biogeographic disjunctions in six cases: (1) Isoëtes asiatica and I. truncata; (2) Botrychium ternatum; (3) Thelypteris beddomei and T. nipponica—Thelypteris noveboracensis and T. nevadensis; (4) Thelypteris glanduligera and Thelypteris. japonica—T. simulata; (5) Woodwardia japonica and W. virginica; and (6) Woodwardia orientalis and Woodwardia fimbriata. Both vicariance and dispersal have been suggested to be the mechanisms for the formation of the disjunct pattern; and the Beringian region has been an active pathway for the migration of ferns and lycophytes between Asia and North America. Disjunctions of ferns and lycophytes reviewed here have been dated in the Tertiary, and are similar to the ages of eastern Asian–North American disjunctions in seed plants, supporting the close biogeographic co‐diversification of ferns and seed plants. Future studies are needed to estimate divergence times and reconstruct biogeographic events in a broad phylogenetic framework, and to test the morphological stasis hypothesis in disjunct ferns and lycophytes.