Genus

About: Genus is a research topic. Over the lifetime, 68921 publications have been published within this topic receiving 590966 citations. The topic is also known as: monospecies genus & genus (zoology).

An overview of systematics and evolution of ticks.

Abstract: All species of ticks (Acari: Ixodida) are grouped into three families: Argasidae (186 species), Ixodidae (692 species) and Nuttalliellidae (monotypic). Molecular markers have been developed and applied for tick studies along with conventional techniques. The origin of ticks is during the pre-mid Cretaceous period (with both the Argasidae and Ixodidae being established in the middle Cretaceous). Primeval hosts were probably reptiles or amphibians. The Argasidae contains two to five subfamilies according to authors but relationships among its members are far from resolved. The Ixodidae were formed by the basal Prostriata group (genus Ixodes subfamily Ixodinae) and the Metastriata group (all others genera). Conventional classifications considered Metastriata to be divided into Amblyomminae, Haemaphysalinae, Hyalomminae and Rhipicephalinae but evidences shows that part of Amblyomminae (species considered previously as "indigenous Australian Aponomma") are now members of the basal Metastriata subfamily Bothriocrotinae, and Hyalomminae are part of Rhipicephalinae. The former genus Boophilus is included as a subgenus within Rhipicephalus. The validity of tick names is discussed in relation to latest world list of ticks.

The kranz syndrome in the gramineae as indicated by carbon isotopic ratios

Abstract: Ttie Kranz syndrome, as indicated by relatively high "3C/12C ratios is characteristic of 161/2 tribes and about '/2 of the species of the Gramineae. Data are given for 198 species from 129 genera and 47 tribes, and from at least 6 subfamilies of grasses. This information is correlated with data from the literature on anatomical and physiological characters of both Kranz and non-Kranz grasses. All subfamilies, tribes, and genera seem to be uniformly all Kranz or non-Kranz except the subfamily Panicoideae and the genus Palicurn which have both Kranz and non-Kranz species represented.

A new taxonomy of the family Teloschistaceae

Abstract: The lichen family Teloschistaceae is one of the larger families of lichenized fungi. Currently it includes one very large heterogenous genus, Caloplaca, with some 1000 or more species with a vast variation in morphology, anatomy and chemistry. The rest of the family is split into 1015 smaller genera, each with 20 or fewer species. There is no modern classification of the family based on molecular data. Here we attempt a first phylogenetic evaluation of a large part of the family, including a total of 337 species. Of these, 162 were used in a combined phylogenetic analysis of the ribosomal RNA sequence markers nrITS, nrLSU and mrSSU, using Bayesian inference. We also analysed all species using nrITS data, split into four different analyses. As a result we propose a new classification of the family, where a total of 39 genera are recognized, of which 31 are newly described or resurrected. The new genera are: Athallia, Austroplaca, Bryoplaca, Calogaya, Cerothallia, Flavoplaca, Gondwania, Haloplaca, Orientophila, Pachypeltis, Parvoplaca, Rufoplaca, Shackletonia, Scutaria, Sirenophila, Solitaria, Squamulea, Stellarangia, Teloschistopsis, Usnochroma, Variospora, Villophora and Wetmoreana. Resurrected genera are Blastenia, Dufourea, Follmannia, Gyalolechia, Leproplaca, Polycauliona, Pyrenodesmia and Xanthocarpia. The species Orientophila subscopularis is described as new. A third subfamily, Teloschistoideae, is proposed to accommodate the genus Teloschistes and related genera, parallel to the two previously recognized subfamilies Xanthorioideae and Caloplacoideae. We also show the large plasticity in both morphological and anatomical characters between closely related species within genera, indicating the low value of these as evolutionary markers. The secondary chemistry is a better marker in some parts of the family. We recognize a large number of geographically delimited clades with clear centres of evolution, but often showing large variation in morphology and anatomy. (Less)