Meru phyllisae
| Meru phyllisae | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Meruidae | ||||||||||||
| Spangler & Steiner , 2005 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Meru | ||||||||||||
| Spangler & Steiner , 2005 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Meru phyllisae | ||||||||||||
| Spangler & Steiner , 2005 |
Meru phyllisae is a species of beetle that is the only member of the genus Meru , which in turn is the only genus of the Meruidae family, which was newly described in 2005. The species is only known from a single locality in South America.
features
They are tiny, brown-colored beetles with an oval body shape, they are about 0.9 millimeters long and 0.4 millimeters wide. The head is directed forward (prognath) and drawn slightly into the prothorax . It has complex eyes protruding from the contour of the head . The antennae are eleven-limbed, longer than the head and thread-shaped. The first antennae ( scapus ) is small, the second ( pedicellus ) is clearly enlarged. The antenna elements 5, 7, and 9 are significantly longer and thicker than the adjacent ones. The prothorax is somewhat narrower than the elytra , like the elytra, it is dense and roughly punctured. A short, flattened hair emerges from each of the points. Two sutures are visible on the side of the prothorax (diagnostic feature of Adephaga ). On the ventral side of the thorax , the sternites of the middle and posterior segments are fused with each other and with the hind hips. The rear hips have small flat extensions that do not cover the thigh ring (trochanter). The scutellum is not visible. In addition to the bristle-bearing points, the wing covers have two rows with bristle-less row points. The training of the hind wings is dimorphic: some individuals have complete hind wings and are able to fly, in most of them they are shortened. The relatively long legs are unmodified and do not have webbed hair, the tibial spurs are three-pointed, the claws are toothed in a conspicuously comb-shaped manner. Six sternites are visible on the abdomen; the first three are fused together, as is typical of the Adephaga. The first sternite is divided into two by the rear hips protruding backwards. The female carries a short, non- sclerotized ovipositor without attachments (gonocoxite).
The combination of features allows a classification into the aquatic Adephaga (Hydradephaga) without any problems, but not an assignment to one of the families previously described within this group.
Larvae
The larvae are elongated with relatively short legs and 1.6 to 1.8 millimeters long in the last stage, they are brown in color and hard sclerotized. The mandibles are asymmetrical, only the left one has a cavity (canal), the antennae are four-limbed and relatively long. The abdomen consists of nine segments, the eighth is elongated and hides the ninth when viewed from above. There is a pair of open spiracles on each of the abdominal segments two and eight , which suggests air breathing.
Way of life
The only place where Meru phyllisae was found is the locality "El Tobogan" in the Amazon province of Venezuela. Here a river flows like a rapids within the rainforest over a hard, granite edge of the terrain. As is typical for “black water” rivers in the Amazon region, the water is soft with few dissolved salts and acidic (pH 5). The river bed is morphologically complex with waterfall-like rapids, pool-like widenings and branches. The beetle species does not live in the water of the rapids themselves, but is limited to the edge zone of weakly flowing side channels, where it can be found between fallen leaves and roots. The beetles cannot swim. When kept in the laboratory, they occasionally let themselves be carried up to the surface of the water, swam upside down for a while under the surface membrane, and then submerged again. Breeding attempts have failed. The diet of adults and larvae is unknown, it is believed that they live on algae or plant detritus.
Systematics
The discovery of the Meruidae is, after the Aspidytidae in 2002, the second new Adephaga family, which was described within a short time on the basis of new discoveries. The phylogeny of the Adephaga was then revised. After some controversy, it now appears most likely that the Meruidae are sister family to the Noteridae family . According to morphological and molecular investigations, both together form a monophyletic taxon. Although it would therefore be possible to include the species in a redefined family Noteridae, most systematists are of the opinion that it deserves the rank of a family of its own because of its peculiar morphology and way of life.
Meru phyllisae is one of the smallest known Adephaga and one of the smallest free-living beetles at all. Apart from the miniaturization, the species corresponds in morphology and way of life to the image one makes of a species of the common parent group of the suborder Adephaga.
swell
- Paul J. Spangler & Warren E. Steiner Jr. (2005): A new aquatic beetle family, Meruidae, from Venezuela (Coleoptera: Adephaga). Systematic Entomology 30, 339-357. doi : 10.1111 / j.1365-3113.2005.00288.x .
- Yves Alare, Andrew EZ Short, Mauricio Garcia, Luis Joly Larval Morphology of Meruidae (Coleoptera: Adephaga) and Its Phylogenetic Implications Annals of the Entomological Society of America Vol. 104, no. 1: 25-36.
- Beutel, Rolf G., Balke, Michael, Steiner, Warren E. (2010): 3.2. Meruidae Spangler and Steiner 2005. In: Leschen, Richard AB, Beutel, Rolf G., Lawrence, John F. (editors): Handbook of Zoology. Volume 4: Arthropoda, 2nd half: Teilband / Part 39 Coleoptera, Beetles, Volume 2, Morphology and Systematics (Elateroidea, Bostrichiformia, Cucujiformia partim). (de Gruyter).
- Andrew Edward Z. Short, Yves Alarie, Mauricio Garcia, Luis J. Joly (2012): Are noterids specialized meruids (Coleoptera, Adephaga)? A reply to Dressler et al. Systematic Entomology Volume 37, Issue 3: 417-419. doi : 10.1111 / j.1365-3113.2012.00626.x .
- Warren Steiner, Alex Wild, Andrew Short (2010) Meruidae Spangler and Steiner 2005. Meru phyllisae Spangler and Steiner 2005. Version August 17, 2010. [1] in The Tree of Life Web Project.