Topic
Microcephala
About: Microcephala is a research topic. Over the lifetime, 68 publications have been published within this topic receiving 697 citations.
Papers published on a yearly basis
Papers
TL;DR: The characteristic evolutionary trends, origin, and taxonomic status of the barred group in the genus Vanmanenia are discussed and it is suggested that V. striata should be restored as a valid species.
Abstract: After comparing specimens of Vanmanenia collected from the Lancang-jiang (the upper Mekong River), Yuan-jiang (the upper Red River), Lixian-jiang (first branch of the Red River), and Jinsha-jiang (the upper Yangtze River) drainages in Yunnan, China, we considered the specimens of Vanmanenia from Shunbi Township, Yangbi County, Yunnan (a branch of the Lancang-jiang drainage basin, the upper Mekong River) a new species, herein named V. microcephala sp. nov. Our investigation also suggested that V. striata should be restored as a valid species. On the basis of the systematic comparison of morphological characteristics of the genus Vanmanenia and based on the combination of the characteristics of the rostral fold, rostral barbels, the bars/marks on the flank, the rows of spots on the paired fins, and the markings on the caudal-fin base, the loaches of Vanmanenia should be divided into three groups: 1) the barred group, characterized by bars on the flank, 2), the cusped rostral fold group, characterized by the rostral fold lobes forming a cusp process, and 3) the barbeled rostral fold group, characterized by the rostral fold lobes specialized as secondary barbels. The barred group differs from congeners in Vanmanenia by the following combination of characters: three rostral lobes with a smooth and arcuate outer edge, a pattern of bars on the flank, and spotless paired fins. This group includes six species: V. crassicauda, V. microcephala sp. nov., V. serrilineata, V. striata, V. tetraloba, and Vanmanenia pseudostriata. The new species, V. microcephala, differs from the other species in the barred group by the following combination of characters: the lateral side of the body with 14–22 vermiculations with widths smaller than the diameter of the eye; the dorsal side of the head covered with a large black blotch; the gill opening smaller and its upper angle aligned with the lower edge of the eye; and the head smaller, head depth 45.2–47.1% head length. The characteristic evolutionary trends, origin, and taxonomic status of the barred group in the genus Vanmanenia are also discussed.
113 citations
TL;DR: The distribution of Odontostilbe microcephala is restricted to the Andean slope of the rio Paraguay basin this paper and the species is distinguished from congeners with subterminal mouth by the elongate body, usually 10-12 gill rakers on upper branch and smaller horizontal orbital diameter.
Abstract: Specimens historically identified as Odontostilbe microcephala from the upper rio Parana and Andean piedmont tributaries of the rio Paraguay are reviewed and split in three species. We found that the distribution of O. microcephala is restricted to the Andean slope of the rio Paraguay basin. The species is distinguished from congeners with subterminal mouth by the elongate body, usually 10-12 gill rakers on upper branch and smaller horizontal orbital diameter (24.6-32.8 % HL, mean 28.7%). Specimens from upper rio Parana constitute two new species, diagnosed from other Cheirodontinae by the presence of mesopterygoid teeth, grouped on median portion and forming a continuous row. The new species are distinguished from each other by having premaxillary teeth with five cusps vs. nine cusps and by the number of lamellae in left and right sides of central median raphe of olfactory rosette with 20-21 vs. 11-12.
98 citations
TL;DR: In this paper, changes in species composition of the periphyton on introduced substrates were determined in an oligotrophic mountain stream subject to long-term heavy metal contamination.
Abstract: SUMMARY. 1. Changes in species composition of the periphyton on introduced substrates were determined in an oligotrophic mountain stream subject to long-term heavy metal contamination.
2. At the upstream control site, the numerically most abundant taxa were Bacillarioph yta i(Achnanlhes minutissima, Achnanthes microcephala and Achnanthes linearis) as well as, in summer, the Chlorophyta (Mougeotia spp. and Ulothrix subtilissima).
3. At the downstream contaminated site the periphyton community was totally dominated by Bacillariophyta throughout the sampling period. A, minutissima and A, microcephala were co-dominants during spring. Seasonal succession patterns did not parallel those at the upstream site. Chlorophyta were virtually absent and A. minutissima comprised 94% of the community during summer.
4. Species diversity, species evenness and dissimilarity index were utilized to detect differences in species composition, abundance and number. Slight differences were found in spring samples while summer samples indicated major differences between sampling sites.
68 citations
TL;DR: In this paper, the authors investigate how intraspecific (density-dependent) competition for nutrients by the diatom Nitzschia microcephala affects the level of oxidative stress in the algal cells as well as their production of pigments and thiamine.
53 citations
TL;DR: The results provide a counter example to theories predicting that the impact of specialist herbivores on seedling recruitment is greatest in the vicinity of parent plants, both in the presence and absence of perennial grasses.
Abstract: Survivorship of Gutierrezia microcephala (Compositae) seedlings was studied in an undisturbed arid grassland and in experimental plots where various components of the natural vegetation were removed following seed germination The major causes of seedling mortality were herbivore damage from the specialist grasshopper, Hesperotettix viridis, and drought stress associated with competition from established plants The relative intensity of these mortality factors varied strongly with seedling size Large seedlings had higher overall survivorship but were most likely to be killed by defoliation; most small seedlings died of drought stress In plots where all perennial grasses were removed (leaving established G microcephala plants), seedling survivorship was 5 times greater than in undisturbed vegetation Surviorship in plots where both grasses and mature G microcephala were removed was slightly poorer than in undisturbed vegetation due to a large increase in mortality from defoliation From May–August, when the herbivore H viridis was abundant, seedling survivorship was better in the immediate vicinity of mature conspecific plants than in plots lacking mature G microcephala, both in the presence and absence of perennial grasses These results provide a counter example to theories predicting that the impact of specialist herbivores on seedling recruitment is greatest in the vicinity of parent plants
51 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 3 |
| 2019 | 2 |
| 2018 | 1 |
| 2017 | 4 |
| 2016 | 1 |
| 2015 | 3 |