Large Number Of Genera Research Articles

Cytology of the Tradescantieae

The value of cytology to the systematist in phylogenetic studies has been pointed out by many workers (Stebbins 1950) and the specific aid that the Commelinaceae might derive from such a study was suggested by Anderson and Sax (1936) in their cytological monograph of the family. Studies in the cytology and the taxonomy of the family have not been abundant in the past fifteen years but some have been made. The most recent taxonomic treatment was that of Woodson (1942) in which some generic changes were made and the tribe Tradescantieae was delimited as it is used in this study. The tropical members of this tribe are poorly understood, both cytologically and taxonomically, and monographs in both phases are badly needed. It is hoped that this study may be of some value toward that end and will bring the cytological literature up to date. Cytological studies were made using the smear technique and the chromosomes were stained in aceto-carmine or orcein. Herbarium specimens with photomicrographs have been made for most of the species studied and these are deposited in the Missouri Botanic Garden Herbarium. Acknowledgment is due R. E. Woodson, U. T. Waterfall, and H. J. Kidd for assistance in identifying these materials. Tripogandra. A large number of genera have been proposed in the past to exclude different elements from Tradescantia because of the dissimilarity of the stamens or the absence of foliaceous bracts. Woodson (1942) places them all in this genus. Two basic chromosome numbers, 6 and 8, are known. Eight appears to be widespread but at present only two cases of six are known. Among those with a basic number of eight, two have been previously recorded, T. disgrega by Darlington (1937), and T. grandiflora by Wu (1941). T. disgrega is a diploid with chromosomes of medium size, of which one is sub-median and seven are sub-terminal in their primary constrictions. T. grandiflora is a tetraploid also with medium sized chromosomes of which 14 have terminal or sub-terminal constrictions and two are median. T. elongata has been reported as 2n = ca. 50 (Simmonds 1954) and in all probability has eight as a basic number. In this study T. pflanziil and T. amplexicaulis are found to be diploids I The identity of this species aiid its inclusion in this genus is questionable. The material was received as Descantaria pflanzii but it has not been checked against the original description. It has many characteristics of Tripogandra cutmanensis and also some of T. elongata but is certainly not typical of either. To my knowledge the species has not been previously treated as Tripogandra, nevertheless it has been included here in this study beause of its cytological and morphological similarities. 30

Geographical distribution of fungi

During a sojourn of some years in Manitoba, I became impressed by the large number of genera and species of fungi there in an environment that I had supposed would be unfavorable for them. Diligent collecting, by a few others and myself, disclosed 2,625 kinds, including 98 myxomycetes. It seemed evident that more than 5,000 species must be present (6), though only some 1,200 phanerogams are known to grow there without cultivation, and a hundred of these are introduced weeds or escapes. Green plants, then these fungi, had arrived and established themselves during not more than 25,000 years since the last glacier retreated. After some thought and analysis I concluded (5) that at least twice as many phanerogams as fungi had been described for the world, but that in any state or country the number of species of fungi is likely to exceed the number of species of phanerogams because of the greater average range of a fungus; that the smaller the area surveyed, the greater is the excess of fungi; that saprophytic fungi generally have wider distribution than parasitic; and that distribution of hosts and substrata, principally flowering plants or their remains, has more influence than climate upon distribution of fungi. Those conclusions are fairly obvious, but it should be possible to extend them. I now realize that a number of Manitoban fungi were not good morphologic species; that I had given most of my attention to the fungi of temperate regions, and therefore underestimated the effect of climate. The study of distribution may be approached from various angles, from that of the whole world and all time to that of today's dispersal over one acre. I happened to be present during the arrival of a few fungi in Manitoba (5, 8); those recognised as new were all parasites of cultivated plants; I knew of no sure means of ascertaining when other fungi had reached the Province.

Cytology and Taxonomy of Hebe, Veronica and Pygmæa

CYTOLOGICAL evidence has materially assisted towards clarifying taxonomic relationships in a large number of genera. As a rule, systematic and cytological approaches have led to conclusions which were in general agreement. Recent cytological work on the related genera Hebe and Veronica, however, pointed to a discrepancy between cytological and taxonomic evidence. This has now been removed by the discovery that the latter was based on erroneous observations.

New Parasites of the Genus Orientophorus, n.gen. (Family Fellodistomidae) from an Indian Fresh-Water Fish, Clupea ilisha

The family Fellodistomidae Nicoll 1913 comprises two subfamilies, Fellodistominae Nicoll 1909 and Haplocladinae Odhner 1911, which are composed of a large number of genera of small flukes, all parasitic in fishes. The type genus of the family was described by Stafford in 1904 from the gall bladder of a Canadian wolf-fish, Anarrhichas lupus. Subsequently several new genera have been added from European and American fishes, but until now no representative of the family has been reported from India.

Studies in African Tachinidae (Diptera).—II

In several previously published papers dealing with African Diptera I have described a number of species belonging to the genus Sturmia, Desvoidy, but up to the present time have not had sufficient material available to warrant the preparation of a key to the species, nor have I had an opportunity of studying the species in sufficient detail to decide upon characters of value in their classification. However, since many species were reared and it was desirable to have names for them in order that they might be used in reports by various Entomologists in Africa, a number of the species were described, and it has since been possible to make considerable progress in the study of the whole. As a result a key to the species belonging to this genus is now presented, and it is hoped that it will be of assistance in identifying the representatives of this difficult group.It is further hoped that arrangements may be made in the near future for the publication of a key to the genera of the Tachinidae, since it is obvious that with the very large number of genera described, the description of an additional genus, or even of new species in old genera, conveys little of the true relationships of the forms described and merely adds to the difficulty of making determinations.

The Coccidae of South Africa—V.

This subfamily comprises a large number of genera, which are, as a rule, easily distinguished by the presence or absence of secretionary matter in one form or another. All agree, however, in having the anal ring with a number of hairs and, further, in having the hind margin cleft. The anal ring is covered above by a pair of more or less triangular plates which are usually densely chitinised. The eighteen genera known to be represented in South Africa are tabulated.

Protostigmata in ascidians

It has been showed that at a certain stage in the ontogeny of Ascidians there is usually a definite number of stigmata or gill slits, which are elongated dorsorventrally and arranged in a longitudinal series on each side of the pharynx. To these the name protostigmata was given by Garstang in 1892. The stigmata of the adult differ from these in being usually very numerous, indefinite in number and elongated antero-posteriorly. In 1904 Julin and Damas made two separate proposals to base the classification of the Tunicates on the condition of the protostigmata. As these proposals differed rather widely from each other and from the current classifications based upon the adult condition, I have taken up the question as far as it conerns the Ascidians and have investigated the origin of the stigmata in a large number of genera. I have been able to confirm for myself very many of the observations that have been published regarding the origin of the stigmata in the genera Holozoa [Distaplia], Clavelina, Ciona, Corella, Cæsira [Molgula], Botryllus and Dendrodoa (Styelopsis) . In addition I have investigated the genera Amaroucium, Polycitor [Distoma], Sycozoa [Colella], Ascidiopsis (very near Ascidiella and Phallusia , which have been studied by others). The last three genera belong to the family Tethyidæ [Cynthiidæ], no members of which have been previously investigated as to the origin of the stigmata.

REMARKS ON THE FAMILY BOMBYCIDÆ

In the American classification of the Lepidoptera, the Bombycidæ occupy a place between the Zygænidæ and the Noctuidæ. They include a large number of genera and species, and are well represented on this continent. The principal characteristic of the family is that from which it derives its name of Bombycidæ,—or spinners,—the power the caterpillars have of producing a silken fibre, which they use in spinning a cocoon in which to pass the pupa stage of their existence. The Silk-worm moth, Bombyx mori, is the typical species of the family. Some genera, however, do not produce silk in any quantity. They are also remarkable as a family for the imperfectly developed mouth parts in the perfect insect. In nearly all of them the tongue is short, and in some species wanting, and the other parts of the mouth so imperfect that it is not probable the insects feed at all in the perfect state.