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Metrioxenini | |
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Tribe: | Metrioxenini Voss, 1953 |
Genera | |
Afrocorynus | |
Synonyms | |
Metrioxeninae Zherikhin & Gratshev, 1995 [1] |
Metrioxenini (metrioxenines) are a tribe of belids, primitive weevils of the family Belidae, containing about 30 species. They are only found in two widely separated areas, Southeast Asia extending to Indonesia, and South Africa. In the Paleogene, they were found at least in North America and Europe also, occurring perhaps across the entire Northern Hemisphere. [1]
As in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae). They are far less characteristic than their presumed closest living relatives, the Aglycyderini. They can be recognized by the sharp-sided rostrum ("snout"). Also, their eyes are bordered by a wide and ridged groove. Metrioxena shows two sharp ribs on each elytron, which are absent in the other genera. These, by contrast, have their tarsal claws fused together at the base (they are unfused in Metrioxena) and grooves on the pygidium which are absent in Metrioxena. [1]
The type genus Metrioxena contains twelve described species apart from the fossil ones mentioned below. They are today restricted to parts Southeast Asia, extending into the Indonesian archipelago. Roughly, they occur between Thailand and the Philippines and from Malaysia to the Tanimbar Islands. They have been found on Sumatra, Java, Sulawesi and offshore Ternate but are hitherto unknown from Borneo and the Lesser Sunda Islands where they conceivably might also occur. Considering that in the Paleogene the genus (or very close relatives) were found in North America and Europe, it may well be that the present distribution is a relict of a formerly Holarctic range. The Paleogene was warmer than our time, and the climate in today's temperate latitudes was by then indeed more like that in today's Southeast Asia. [1]
Afrocorynus contains presently two described species, which are only known to occur in the mountains and hills that extend on the southern coast of South Africa, between Mosselbay in the west, Grahamstown in the east, and the Karoo inland. Hispodes occurs in similar habitat extending eastwards and inland, with the single described species (H. spicatus) found hitherto only in the Katberg region, and an undescribed species known from the Drakensberg escarpment south of Tzaneen. [1]
Metrioxena apparently feed only on Arenga sugar palms (Arecaceae). Larvae, though little is known about them, are probably eating the wood of dead or dying trees, while the adults eat pollen. The Paleogene fossil Metrioxena electrica was found in conifer amber from the Baltic region, where palms are known to have grown some 50 million years ago. [1]
The South African species seem to be dependent on the Knysna-Amatole montane forests biome. Very little is known about their host plants. The first specimen of Afrocorynus asparagi was found on "wild asparagus" but this seems a most unlikely host plant for Belidae; in any case it has never again been found on an Asparagus species but only on Putterlickia pyracantha (Celastraceae). Hispodes spicatus has not been recorded from any other plant than Rhoicissus tridentata (Vitaceae). And though the Knysna-Amatole montane forests hold the conifers Podocarpus and African cypress (Widdringtonia), which seem plausible host plants considering what other Belidae feed on, the Rosidae P. pyracantha and R. tridentata actually grown in shrubby habitat interspersed with the actual montane forest. It may be that H. spicatus larvae feed - atypically for the family - on flower buds, as they have not been found in immature fruits which, apart from wood, are the other known food-type of Belidae larvae. More probably, they feed on the decaying wood like most of their relatives. [1]
Presumably, the original host plants of belid larvae were conifers, namely Araucariaceae. From there the Metrioxenini shifted to palms. The African lineages might have host-shifted to the Rosidae shrubs directly (from conifers) or indirectly (via palms, which used to occur in their present range but eventually disappeared). This issue could be resolved by checking whether the Pondoland palm ( Jubaeopsis afra ), the only survivor from the original palmtree flora of Southern Africa, is host to a metrioxenine. [1]
The three currently recognized living genera of Metrioxenini are occasionally assigned to subtribes, that seem almost superfluous, as it seems that the presently monotypic Metrioxenina simply represent a more basal lineage and the Afrocorynina ( Afrocorynus and Hispodes ) a more advanced one. But the relationship among the genera is not resolved with complete certainty. Indeed, Metrioxena was sometimes placed in the Oxycoryninae and the Afrocorynina elevated to full tribe status, but this seems to be in error. It is possible that Metrioxena iwill eventually be split up into several genera (e.g. Prometrioxena).Hispodes on the other hand is occasionally separated in a subtribe of Hispodini, which Marvaldi and co-writers 2006 find to be an unwarranted arrangement, since it would render all subtribes monotypic and thus redundant. [1]
The fossil record shows that the Metrioxenini were well distinct by the mid-Paleogene, about 50 million years ago (mya). The belids as a whole are of Jurassic origin, [2] and the Metrioxenini must thus have evolved in the Late Cretaceous or perhaps Paleocene, roughly some 100-60 mya. [1]
There are three fossil species of Metrioxenini known to date: Paltorhynchus bisulcatus of the Early Eocene Green River Formation and "Paltorhynchus" narwhal from the latest Eocene or earliest Oligocene of the Florissant Fossil Beds are both from North America. If the latter species actually belongs in the modern genus Metrioxena , since it is the type species of Paltorhynchus , that name would become a junior synonym of Metrioxena and a new genus would have to be established for the more primitive "P." bisulcatus. That species might represent another genus of the Metrioxenina or a still more basal member of the tribe. Metrioxena electrica known from Baltic amber and of comparable age to the North American fossils, is sometimes separated in Archimetrioxena. [1]
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow slowly and have long lifespans. Because of their superficial resemblance to palms or ferns, they are sometimes mistaken for them, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones.
Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than 6 mm in length – and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, with most of them in the family Curculionidae. It also includes bark beetles, which while morphologically dissimilar to other weevils in lacking the distinctive snout, is a subfamily of Curculionidae. Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil, which belongs to the family Ptinidae.
Nothofagus, also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America and east and southeast Australia, New Zealand, New Guinea, and New Caledonia. The species are ecological dominants in many temperate forests in these regions. Some species are reportedly naturalised in Germany and Great Britain. The genus has a rich fossil record of leaves, cupules, and pollen, with fossils extending into the late Cretaceous period and occurring in Australia, New Zealand, Antarctica, and South America.
The bean weevils or seed beetles are a subfamily (Bruchinae) of beetles, now placed in the family Chrysomelidae, though they have historically been treated as a separate family. They are granivores, and typically infest various kinds of seeds or beans, living most of their lives inside a single seed. The subfamily includes about 1,650 species and are found worldwide.
Laurel forest, also called laurisilva or laurissilva, is a type of subtropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glossy and elongated leaves, known as "laurophyll" or "lauroid". Plants from the laurel family (Lauraceae) may or may not be present, depending on the location.
Belidae is a family of weevils, called belids or primitive weevils because they have straight antennae, unlike the "true weevils" or Curculionidae which have geniculate (elbowed) antennae. They are sometimes known as "cycad weevils", but this properly refers to a few species from the genera Parallocorynus and Rhopalotria.
The Afromontane regions are subregions of the Afrotropical realm, one of the Earth's eight biogeographic realms, covering the plant and animal species found in the mountains of Africa and the southern Arabian Peninsula. The Afromontane regions of Africa are discontinuous, separated from each other by lower-lying areas, and are sometimes referred to as the Afromontane archipelago, as their distribution is analogous to a series of sky islands.
Brentidae, sometimes known as the primitive weevils, is a cosmopolitan family of primarily xylophagous beetles also known as straight-snouted weevils. The concept of this family has been expanded with the inclusion of three groups formerly placed in the Curculionidae; the subfamilies Apioninae, Cyladinae, and Nanophyinae, as well as the Ithycerinae, previously considered a separate family. They are most diverse in the tropics, but occur throughout the temperate regions of the world. They are among the families of weevils that have non-elbowed antennae, and tend to be elongate and flattened, though there are numerous exceptions.
The palm weevil Rhynchophorus ferrugineus is one of two species of snout beetle known as the red palm weevil, Asian palm weevil or sago palm weevil. The adult beetles are relatively large, ranging between 2 and 4 centimetres long, and are usually a rusty red colour—but many colour variants exist and have often been classified as different species. Weevil larvae can excavate holes in the trunks of palm trees up to 1 metre (3.3 ft) long, thereby weakening and eventually killing the host plant. As a result, the weevil is considered a major pest in palm plantations, including the coconut palm, date palm and oil palm.
Nemonychidae is a small family of weevils, placed within the primitive weevil group because they have straight rather than geniculate (elbowed) antennae. They are often called pine flower weevils. As in the Anthribidae, the labrum appears as a separate segment to the clypeus, and the maxillary palps are long and projecting. Nemonychidae have all ventrites free, while Anthribidae have ventrites 1-4 connate or partially fused. Nemonychidae lack lateral carinae on the pronotum, while these are usually present, though may be short, in Anthribidae.
Jubaeopsis afra, the Pondoland palm, is a flowering plant species in the palm family (Arecaceae). It belongs to the monotypic genus Jubaeopsis.
Calyptrocalyx is a monoecious genus of flowering plant in the palm family found in Papua New Guinea and the nearby Maluku Islands. Ranging from small to large, the palms in this genus are increasingly found in cultivation owing largely to their purple, red, and orange colored, new foliage. At least 26 species have been described while others, known only by local names, have not yet received a taxonomic account. Palms formerly classified within Paralinospadix have been incorporated into this genus. It is named from 2 Greek words meaning 'covered' and 'calyx'.
Eobelinae are an extinct weevil subfamily that throve in the late Mesozoic. They belong to the family Nemonychidae. The Eobelidae were widespread, occurring at least in Central Asia, Spain and Brazil during the Late Jurassic and Early Cretaceous.
Oxycoryninae are subfamily of primitive weevils of the family Belidae, but sometimes treated as a distinct family Oxycorynidae. Like in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae), and their larvae feed on the wood of diseased or dying plants or on deadwood or fruits; they tend to avoid healthy plants.
Belinae are a Gondwanan subfamily of beetles which belong to the belids, primitive weevils of the family Belidae. Like in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae). The Belinae make up the bulk of the diversity of living belid genera. They are found in the Australia-New Guinea-New Zealand and South America.
Aglycyderini is a tribe of belids, primitive weevils of the family Belidae. Like in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae). They occur only on the Pacific Islands and in the Macaronesian region.
Oxycorynini are a tribe of American belids, primitive weevils of the family Belidae. Like in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae). In contrast to other Belidae, Oxycorynini larvae feed on flowers or several types of fruit.
Cryosophileae is a tribe of palms in the subfamily Coryphoideae. The tribe ranges from southern South America, through Central America, into Mexico and the Caribbean. It includes New World genera formerly included in the tribe Thrinacinae, which was split after molecular phylogenetic studies showed that Old World and New World members of the tribe were not closely related.
Calamoideae is a subfamily of flowering plant in the palm family found throughout Central America, South America, Africa, India, China, Southeast Asia and Australia. It is represented by 21 genera - containing nearly a quarter of all species in the palm family - including the largest genus, Calamus, the type genus of the group. Only four are found in the New World while the rest are Old World denizens, usually found in equatorial swampland or along tropical coastlines.