Pleocoma
| Pleocoma | ||||||||||||
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Pleocoma |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Pleocomidae | ||||||||||||
| LeConte , 1861 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Pleocoma | ||||||||||||
| LeConte , 1856 |
Pleocoma is the only genus of the family Pleocomidae within the beetle suborder Polyphaga .
features
Beetle
The beetles are 16.5 to 29.0 millimeters in length (males) and 19.5 to 44.5 millimeters (females). Its strong body has a broad oval shape and is strongly convex. Her back is hairless, the building side is densely covered with fine, long hair. The beetles are reddish brown to black, with differently colored hair. The head is neither bent sharply down, nor can it be drawn in. The antennae are eleven-segmented and have a four- to eight-segment club, similar to the Melolonthinae . The mandibles and maxillae are regressed. The maxillary and labial palps are four-limbed. The beetles are the only ones within the Scarabaeoidea in which the indentations for the hips ( coxes ) of the front legs are open. The tracheas on the first through eighth abdominal segments are functional and are located in the pleural membranes . The genitals of the males consist of a symmetrical, triple lobe. The genital capsule is well developed. The females have 14 to 25 egg tubes ( ovarioles ) per ovary , which is not found in any other family of the Scarabaeoidea. Only the males are winged.
The Pleocoma have several unique, mainly primitive, features such as the indentations for the fore hip, the large number of female ovaries, and the extremely long-lived larvae. A few others might represent synapomorphies . The autapomorphies of the pleocoma in the imagines include: an epipharynx of the IMP type, the missing prostheca and ligula , the open front hips, on the wings the dorso-proximal lobe of 2Ax is exceptionally small and at the base extremely narrow, the subalar point to which the tendon has grown is extremely long and narrow, 2BP BMP is strongly convex and extremely narrow and more than 12 ovarioles in females, which are also wingless. The autapomorphies of the larvae are: a round, small, flat "sensory window" on the apical half of the last antennae, the partially receding claws, their hair, which is longer than the claws themselves, the clearly forward curved claws on the middle and rear Legs and the more than three larval stages.
Larvae
The body of the larvae is broad “C” -shaped. The third to seventh body segments are divided into three or four folds on the back. Point eyes ( Ocelli ) are missing. The antennae are tripartite and do not have a large sensory mark. The mandibles are asymmetrical, have an extension on the ventral side and there is no stridulation area. Galea and Lacinia are clearly separated from each other. Noise-generating organs are formed on the middle and rear legs. The hind legs are normal and not shortened. The tracheal openings are sieve-shaped (cribriform).
Distribution and way of life
The distribution of the beetles is restricted to western North America from Washington to Baja California in Mexico.
The beetles are active early in the morning during the cold season. The males actively fly during rains. The females attract them with pheromones . Mating takes place either on the ground or in the females' burrows for the larvae. Mated females return to their burrow and allow their eggs to mature for up to several months before laying them in a spiral in the burrow. The adults have neither functioning mouthparts nor a digestive tract and accordingly do not consume any food. The larvae live for eight to twelve years and are the only ones within the superfamily to go through more than three, namely nine larval stages. They develop in the ground and feed on roots. They are well adapted to digging in the ground.
Taxonomy and systematics
The genus Pleocoma was originally counted among the dung beetles (Geotrupidae). The taxon is closely related to the Bolboceratidae . There are 26 species known.
supporting documents
Individual evidence
- ↑ a b c d e Rolf G. Beutel, Richard AB Leschen: Handbuch der Zoologie - Coleoptera, Beetles, Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) . 1st edition. de Gruyter , 2005, ISBN 3-11-017130-9 , p. 373 f . (English).
literature
- Rolf G. Beutel, Richard AB Leschen: Handbuch der Zoologie - Coleoptera, Beetles, Volume 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim) . 1st edition. de Gruyter , 2005, ISBN 3-11-017130-9 (English).
