Mucroberotha copelandi (Neuroptera: Mantispoidea: Rhachiberothidae: Rhachiberothinae: Mucroberotha)
The insect of the week, Mucroberotha copelandi, belongs to the small family Rhachiberothidae, or thorny lacewings. The family is divided into two subfamilies, Rhachiberothinae and Paraberothinae. All of the living species belong to the subfamily Rhachiberothinae in which there are only 14 extant species in 4 genera, all of them found only in the Afrotropics. All 17 of the genera of Paraberothinae are extinct, with fossil evidence placing them in the Cretaceous. This suggests that at one time the Rhachiberothidae was a far more robust lineage than it is presently, perhaps soon (in evolutionary time) to leave the living world.
Mucroberotha is a small genus, in size and number of species. There are only 7 known species and until the collection of M. copelandi in southern Kenya and Northern Tanzania the genus was known only from southern Africa and northern Ethiopia. The present distribution implies that there are more species to be found between southern and eastern Africa. Mucroberotha is a member of the Neuroptera, a moderately sized holometabolus order, but small compared to the other very large holometabolus orders (e.g. Lepidoptera, Diptera, Hymenoptera, etc.). Holometabolus development (also called complete metamorphosis) is characterized by the breakdown of tissues in the pupal stage, the reorganization of which ultimately produces an adult that looks (and acts) completely differently than it did as a larva. This type of metamorphosis is also called complete metamorphosis, the astounding changes occurring in the pupal stage. In contrast, in hemimetabolous species such as the true bugs (Hemiptera) the larval stages resemble the adult, only smaller. There is no true pupal stage, and the adults and larvae tend to feed on the same plants. In contrast, holometabolus insects avoid intraspecific competition for food and space between larva and adult. For example, consider the life history of the butterfly. The larva is “wormlike”, matures and produces a pupa (chrysalis) in which the tissues are reassembled, the adult emerging soon thereafter. The larva of a butterfly feeds on leaves, the adult feeds on nectar and liquids of various origin. The two life stages are resource independent of each other.
The Neuroptera most familiar to us are the ant lions (see 2nd image) which, as larvae, build inverted, conical, traps of sand or loose soil. The larva waits out-of-sight at the bottom of the cone, gabbing prey that are unlucky enough to fall into the trap. Many are the unfortunate ants whose last glimpse of life is sliding down into the open jaws of the ant lion.
The biology of Mucroberotha is unknown except that the forelegs of adults are armed with teeth, like those of the other members of the superfamily Mantispoidea, suggesting that Mucroberotha too are predacious as adults. Individuals of the closely related family Berothidae, in which Mucroberotha was once included, are known to prey on termites. As for larval behaviour nothing is known except that it has been studied in larvae of the closely related Mantispidae (mantidflies). Mantispinae larvae are predaceous on spider eggs. To find their prey they may directly bore through the silken fibres of the spider egg sac after which they suck out the contents of several eggs. Alternatively, the mantispid larvae may attach themselves to the adult spider and be carried phoretically, remaining attached to it while the egg sac is being constructed. Mucroberotha may use those or similar behaviours to capture their prey.
The holotype of Mucroberotha copelandi was collected in a sweep net at the western base of the Ngong Hills in southern Kenya. It turned out to be a new species.
Credits: Dr Robert Copeland