Embryological features of taxonomic significance in the genus Nyssa

1971 ◽  
Vol 49 (4) ◽  
pp. 505-514 ◽  
Author(s):  
Shiv R. Tandon ◽  
J. M. Herr Jr.
Keyword(s):  
Growth Pattern ◽  
Distinct Species ◽  
Archesporial Cell ◽  
Taxonomic Significance ◽  
Nyssa Aquatica ◽  
Cellular Endosperm ◽  
Occasional Occurrence

The embryological investigation of Nyssa aquatica L., N. biflora Walt., and N. sylvatica Marsh. reported here clearly delimits similarities and variations among the three species. Such evidence supports the retention of Nyssaceae as a family apart from Cornaceae. The major distinctions between the two families occur in the differentiation of the megasporocyte, development of the nucellus, degeneration of defunct megaspores, and growth pattern of the megagametophyte. Major points of similarity between the two families are the occurrence of unitegmic, pendulous, anatropous ovules, a single hypodermal archesporial cell, unequal dyad cells, hooked synergids, polar nuclei fusing before syngamy, and cellular endosperm. These same features serve also to show that Nyssaceae belongs in the order Cornales rather than Myrtales as suggested by several workers.Strong evidence is provided for the recognition of N. biflora as a distinct species rather than a variety of N. sylvatica as previously proposed by several workers. Points of distinction between the two taxa are found in the shape of the ovule, growth pattern of the nucellar apex and integument, position of the nuclei in the four-nucleate megagametophyte, and the growth pattern of the megagametophyte.Embryological features further indicate a closer relationship between N. aquatica and N. biflora than between either one and N. sylvatica. The features of greatest similarity between N. aquatica and N. biflora are the shape of the ovule and megasporocyte, growth pattern of the megagametophyte, presence of hooked synergids, and the occasional occurrence of bisporic megagametogenesis.

A scanning electron microscopic study of the eggs of Culicoides variipennis (Diptera: Ceratopogonidae)

1987 ◽  
Vol 45 ◽  
pp. 884-885 ◽  
Author(s):  
R. A. Nunamaker ◽  
C. E. Nunamaker ◽  
B. C. Wick
Keyword(s):  
Distinct Species ◽  
Hemorrhagic Disease ◽  
Insect Vector ◽  
Electron Microscopic ◽  
Important Species ◽  
Scanning Electron Microscopic Study ◽  
Laboratory Colony ◽  
Culicoides Variipennis ◽  
Morphological Differences ◽  
Scanning Electron

Culicoides variipennis (Coquillett) is probably the most economically important species of biting midge in the U.S. due to its involvement in the transmission of bluetongue (BT) disease of sheep, cattle and ruminant wildlife, and epizootic hemorrhagic disease (EHD) of deer. Proposals have been made to recognize the eastern and western populations of this insect vector as distinct species. Others recommend use of the term “variipennis complex” until such time that the necessary biosystematic studies have been made to determine the genetic nature and/or minute morphological differences within the population structure over the entire geographic range of the species. Increasingly, students of ootaxonomy are relying on scanning electron microscopy (SEM) to assess chorionic features. This study was undertaken to provide comparative chorionic data for the C. variipennis complex.Culicoides variipennis eggs were collected from a laboratory colony maintained in Laramie, Wyoming.

Structure, ontogeny, classification, taxonomic significance of trichomes and extra-floral nectaries in cultivars of cotton

1981 ◽  
Vol 92 (7-8) ◽  
pp. 551-556
Author(s):  
J. A. Inamdar ◽  
Venigella S. Rao
Keyword(s):  
Taxonomic Significance ◽  
Floral Nectaries

Structure, development, organographic distribution and taxonomic significance of trichomes in nine species ofVerbena

1983 ◽  
Vol 94 (5) ◽  
pp. 323-333
Author(s):  
L. Mathew ◽  
G. L. Shah
Keyword(s):  
Taxonomic Significance ◽  
Structure Development

Taxonomic significance of stomatal complex in the Portulacaceae

1986 ◽  
Vol 97 (11-12) ◽  
pp. 763-766
Author(s):  
Bio Louis Nyananyo
Keyword(s):  
Taxonomic Significance ◽  
Stomatal Complex

Identification of a CVD Synthetic Diamond with a 'Tree Ring' Growth Pattern

2015 ◽  
Vol 34 (8) ◽  
pp. 702-710
Author(s):  
Yan Lan ◽  
Rong Liang ◽  
Taijin Lu ◽  
Yong Zhu ◽  
Tianyang Zhang ◽  
...  
Keyword(s):  
Tree Ring ◽  
Growth Pattern ◽  
Synthetic Diamond

Spider diversity in the Bukit Timah Nature Reserve, Singapore

2019 ◽  
Vol 71 ((suppl.1)) ◽  
pp. 209-243
Author(s):  
J.K.H. Koh ◽  
D.J. Court
Keyword(s):  
Nature Reserve ◽  
New Records ◽  
Secondary Forest ◽  
Distinct Species ◽  
Primary Forest ◽  
Preliminary Results ◽  
Vegetation Zones ◽  
Comprehensive Survey ◽  
Quantitative Analyses ◽  
First Time

This paper discusses the preliminary results of the first comprehensive survey of the spiders of the Bukit Timah Nature Reserve (BTNR) in Singapore. Two plots were established in each of the three zones of vegetation, viz., primary forest, old secondary forest, and maturing secondary forest. They were repeatedly sampled over an 18-month period. Sorting of the collection so far suggests that the three vegetation zones harbour rather different spider assemblages. Only ~9% of the total spider fauna recovered was shared by all three zones. The results have also yielded a preliminary picture of dominance, abundance and rarity. Although first intended to obtain a baseline for future quantitative analyses, the survey became a testing ground to modify and refine methodology so as to conduct future quantitative surveys with greater scientific rigour. Taxonomic work on the samples so far shows that the spiders in the BTNR span over 43 families, of which six families are listed for the first time in Singapore. The tally is summarised in an interim checklist of BTNR spiders. The checklist, with a total of 317 entries, shows that there are 158 described species of spiders in BTNR, of which 25 species are new records for Singapore. Another 159 morphospecies are provisionally recognised as distinct species, some of which may be new to science. Our observations during the survey have allowed us to provide a narrative of BTNR spider diversity against a backdrop of their microhabitat specialisation.

Paraswammerdamia ruthiella Steuer, 1993 a junior synonym of P. albicapitella (Scharfenberg, 1805) (Lepidoptera: Yponomeutidae)

2020 ◽  
Vol 71 (2) ◽  
pp. 149-150
Author(s):  
David Agassiz
Keyword(s):  
Distinct Species ◽  
Junior Synonym

The case for retaining Paraswammerdamia ruthiella Steuer, 1993 as a good species is reviewed. It should be regarded as a junior synonym of P. albicapitella (Scharfenberg, 1805), since there is no further evidence that it is a distinct species.

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