Presidential Address—Some Reflections On The Nature Of Species

Background: Variation in the distribution and abundance of woody plants as consequence of disturbances such as fire may be explained by lineage age.

Aims: We tested whether lowland tropical tree lineages that colonise secondary forests are more late-diverging than clades from old-growth forests, and whether tree phylogenetic beta diversity from old-growth to secondary forests is higher in burned than non-burned secondary forests.

Methods: We sampled tree communities in old-growth forests and in secondary forests with distinct disturbance histories (burned and unburned). We calculated mean family age in each plot, and tested for differences among forest types using ANOVA. A phylogenetic fuzzy-weighting procedure was employed to generate a matrix describing the abundance of tree clades per plot, which was then analysed using a principal coordinate analysis.

Results: Most clades found in old-growth forests were underrepresented in secondary forests, which have been heavily colonised by a single species from a young lineage that is not found in old-growth forests. Phylogenetic beta diversity was higher between unburned secondary forests and old-growth forests than between burned secondary forests and old-growth forests.

Conclusions: The capacity of Neotropical trees to colonise secondary forests and persist after fire disturbance may be related to the age of distinct lineages.     

A New Genus and Species—Cycadostrobilus paleozoicus Zhu of Cycadaceae from the Permian of China

This paper describes a new microstrobilus of palaeozoic Cycadaceae collected from the upper part of Lower Shihezi Formation, Dongshan Mine, Taiyuan, Shanxi, China and named it as Cycadostrobilus paleozoicus Zhu, gen. et sp. nov. This new cycad is the oldest microstrobilus to our knowlege of cycads. In the same locality and layer, there are Primocycas chinensis Zhu et Du, Sphenophyllum emarginatum Brongn. , S. costae Sterz. , S. verticallatum (Schloth.) Brongn. , S. oblongifolium (Germ. et Kaulf. ) Ung. , Tingia carbonica (Schenk.) Halle, T. hamaguchii Kon’no, Macrostachys huttoniformis Halle, Sphenopteris norinii Halle, S. firmata Sze, S. gothanii Halle, Sphenopteridium pseudogermanicum (Halle) Gu et Zhi, Pecopteris feminaeformis (Schloth.) Sterz. , P. wongii Halle, P. tuberculata Halle, P. unita Brongn. , P. taiyuanensis Halle, Emplectopteris triangularis Halle, Taeniopteris norinii Halle, T. spp. , Cordaites principalis (Germ.) Gein. , Cornucarpus patulus Halle, Radicites spp. and a few taxa unknown to palaeobotanical data. The authors consider that Cycadostrobilus paleozoicus is the same species as Primocycas chinensis, and its veg.etative leaves are similar to those of the genus Taeniopteris, e.g.T. norinii Halle.     

Friends or Relatives? Phylogenetics and Species Delimitation in the Controversial European Orchid Genus Ophrys

BACKGROUND AND AIMS: Highly variable, yet possibly convergent, morphology and lack of sequence variation have severely hindered production of a robust phylogenetic framework for the genus Ophrys. The aim of this study is to produce this framework as a basis for more rigorous species delimitation and conservation recommendations. METHODS: Nuclear and plastid DNA sequencing and amplified fragment length polymorphism (AFLP) were performed on 85 accessions of Ophrys, spanning the full range of species aggregates currently recognized. Data were analysed using a combination of parsimony and Bayesian tree-building techniques and by principal co-ordinates analysis. KEY RESULTS: Complementary phylogenetic analyses and ordinations using nuclear, plastid and AFLP datasets identify ten genetically distinct groups (six robust) within the genus that may in turn be grouped into three sections (treated as subgenera by some authors). Additionally, genetic evidence is provided for a close relationship between the O. tenthredinifera, O. bombyliflora and O. speculum groups. The combination of these analytical techniques provides new insights into Ophrys systematics, notably recognition of the novel O. umbilicata group. CONCLUSIONS: Heterogeneous copies of the nuclear ITS region show that some putative Ophrys species arose through hybridization rather than divergent speciation. The supposedly highly specific pseudocopulatory pollination syndrome of Ophrys is demonstrably 'leaky', suggesting that the genus has been substantially over-divided at the species level.     

Maesaipsyche mekongensis sp. n. – the Third Species of the Genus from South-East Asia (Trichoptera,Arctopsychidae)

Maesaipsyche mekongensis sp. n. is described from Laos. The type series was collected near the Mekong River, which is suggestive of a potamobiontic habitat of the larvae. The male genitalic apparatus is illustrated.     

On Circumscription of the Genus Prenanthes L. and Notoseris Shih — A New Genus of Compositae from China

After having examined all specimens of the genus Prenanthes L. of Compositae in the Herbarium of Institute of Botany, Academia Sinica, I find that the classic concept on the genus Prenanthes established by G. Bentham in 1873 has not been held exactly by some of European, American, Japanese and Chinese botanists. For example, W. B. Hemsley, S. T. Dunn, A. Franchet, S. Kitamura and C. C. Chang placed plants from China which belong to other groups into the genus; I also find that the classic concept of the genus is not clear. The present paper makes a revision not only on the classic concept of the genus, but also on its concept assumed by the above-mentionded botanists. With the combination of numerous (25-35), white or yellow ligular florets, numerous ribs of achenes, Prenanthes alba L. (Nabalus albus (L.) Shih, comb. nov.) is distinctly different from Prenanthes purpurea L., which has the combination of purple, few (5-15) ligular florests and few ribs of achenes. Nabalus Cass., as a genus established early (1825) by H. Cassini, should be restored. It is not reasonable to treat Nabalus as a subgenus (E. B. Babcock et al. 1947) or a section (S. Kitamura, 1956) or as a synonym (G. Bentham, 1983) of the genus Preanathes L. The present author recognizes seven species in the new revised genus Prenanthes L. in China, 4 of which are described as new. In the genus Nabalus Cass. only one species, N. ochroleuca Maxim., is distributed in Northeast China. As Lactuca melanantha Franch. (1895), Prenanthes henryi Dunn (1903), P. glandulosa Dunn (1903), Lactuca triflora Hemsl. (1888) (it was transferred to Prenanthes L. by C. C. Chang in 1934), Prenanthes formosana Kitam. (1934) and P. wilsoni Chang (1934) all have campanulate involucres, purple phyllaries, purple dorsi-ventrally compressed achenes, longitudinal rids 6-9 on each side of achene truncate and beakless at its apex and pilose tubes of corollae, they should be placed neither into the genus Prenanthes with obtusely tri-or pentagonous, subterete achenes and glabrous tubes of corollae, nor into the genus Lactuca with beak achenes. Besides the above-mentioned species misnamed by some of foreign and Chinese botanists, 6 other species also have the same structure in achenes and corollae. Evidently, they fall into a new genus with the name Notoseris Shih. The new genus Notoseris Shih of the tribe Lactuceae of Compositae seems to be more reminiscent of Lactuca L. than of Prenanthes L. emend. All the 12 species of the genus Notoseris Shih are endemic to China and distributed in the area of south of Yantze River. Of them 6 are new combinations and 6 are described as new.     

The British Species of the Plagiothecium denticulatum–P. silvaticum Group

Abstract

Anomodon viticulosus was subjected to several different patterns of alternating wet and dry periods, and assimilation was measured at intervals over 49 days. Short periods of desiccation intercalated between 6-day moist periods had little effect on subsequent performance. Short moist periods breaking otherwise continuous desiccation had a very pronounced effect in mitigating desiccation damage. The results provide some evidence for a fairly slight, but probably cumulative, specific deleterious effect of drying and remoistening.     

Studies on the Genus Paeonia (1)—Report of Karyotypes of Some Wild Species in China

In the present paper 8 species with 15 populations of the genus Paeonia L. (if P. papaveracea and P. japonica are recognised as species) were collected from Sichuan, Shaanxi and Hebei provinces (see the Appendix for detail of the materials). The micrographs of their somatic metaphase (also Mii in the case of P.veitchii) are shown in Plates 1-4, the karyotype formulae, ranges of chromosome length and classification of karyotypes according to Stebbins (1971) are shown in Table 5: the idiograms in Figs. 1-2, and the parameters of chromosomes in Table 1-4. The essential points are mentioned as follows: (1) Chromosomes of the various species in the section Modan have so far been examined and they are all diploid, the two species in the section Onaepia are also diploid, and thus tetraploids exist only in the section Paeonia. (2) Chromosomes in the genus Paeonia are relatively stable except for the differentiation of ploidy. The karyotypes (Table 1-4) show no differences among different taxa in Sect. Modan and the same can also be said about the taxa in Sect. Paeonia (Table 1). Not only are the karyotypes very similar, but also among the members within either section have the same parameters of chromosomes, and, differences, if occur, are not statistically significant. Between the two sections, however, the situation is different. The arm ratios of the first pairs of chromosomes in Sect. Modan are 1.53, 1.52 and 1.48 (Table 1), but those in Sect. Paeonia are 1.12-1.28 (Table 2-4), 95% confidence limits are 1.46-1.60 for the section Modan and 1.07-1.28 (1.21-1.35 only for PB85078) for the section Paeonia, not overlapping, which indicates that the two sections have differentiated in respect of the first pairs of chromosomes. (3)The population PB85024, which belongs to the P. obovata complex, has a karyotype of 2B (stebbins, 1971), which is a new one in the genus Paeonia. This karyotype is a stable one, for several individuals in the population are uniform in this respect, which shows that Stebbins’ (1971) generalization that all the species in Paeonia have 2A does not hold true. (4) Three populations of P. obovata complex studied in this work from Sichuan and Shaanxi are all tetraploids, and one from Hebei is a diploid. From the present work and the previcus reports, the materials from Japan and Korea, no matter whether flowers are pink or white, are diploids, those from Heilongjiang Province (with both pink and white flowers) (Liu Ming-yuan, personal communication) and from Heibei Province (with pink flowers) in China are also diploids, the one from Sakhalin (pink flowers) is tetraploid, those from Priamur of the Soviet Union are a tetraploid (with white flowers) and a diploid (with pink flowers), and those from Shaanxi (the Qinling Range) and western Sichuan (with both pink and white flowers) are all tetraploids. As far as we have now known, ploidy in this particular complex is correlated with the geographical distribution: diploids are found in the central part, tetraploids occur in the northern limits, and in the south letraploids are the only cytotype. (5) The materials of P. mairei from western Sichuan and Shaanxi (the Qinling Range) are found all to be tetraploids, which shows that two cytotypes, diploid and tetraploid, exist in this species, but the geographical distribution pattern of these two cytotypes is to be revealed in the future investigation.