Friday 8 August 2014

A new species of Scarab Beetle from the Elandsberg Mountains of the Western Cape, South Africa.

Scarab Beetles of the genus Trichostetha occur across southern Africa, reaching their greatest diversity in the Cape Floral Region. One species, Trichostetha fascicularis is found across South Africa and southern Botswana, and is divided into a number of subspecies, but most species have a much more restricted, localized range. The adults typically feed on pollen from a single or small number of flowers, though many species do not appear to feed as adults at all; the adults being very short lived. No larvae of any species of Trichostetha has been described to date. 

In a paper published in the journal ZooKeys on 23 July 2014, Renzo Perissinotto of the Department of Zoology at Nelson Mandela Metropolitan University, Petr Šípek of the Department of Zoology at Charles University in Prague and Jonathan Ball of the Department of Zoology & Entomology at the University of Pretoria describe a new species of Scarab Beetle in the genus Trichostetha from the Elandsberg Mountains of the Western Cape; descriptions of both the adults and the third instar larvae are provided (Insects undergo a set number of moults during their life, with the stages between these moults known as ‘instars’, and the final instar being the adult, often very different to the previous instars as many insects undergo a dramatic metamorphosis with the last moult).

The new species is named Trichostetha curlei, in honour of Alfred Curle, the South African lepidopterist (scientist that studies Butterflies and Moths), who first noted the new species. The adult is a 12.8-18 mm black or dark green Scarab Beetle with white speckles on its elytron (the modified forewings of a Beetle, which form a wing-case protecting the still useable hindwings). The Beetles are covered with white hairs, with the males being notably more hairy than the females.

(Top) Male Trichostetha curlei in (left) dorsal and (right) ventral views. (Bottom) Female in (left) dorsal and (right) ventral views. Lynette Clennell in Perissinotto et al. (2014).

The larvae is a typical Scarab Beetle larvae, reaching 38-41 mm in length (considerably larger than the adult), with a creamy-white body with orange hairs and a dark-brown head. They were found living in underground rock crevices.

The third instar larvae of Trichostetha curlei. Petr Šípek in Perissinotto et al. (2014).

The adults were appeared in November and December (early summer in South Africa), and were found to visit the flowers of a wide variety of plants. However they appear to be incapable of feeding, instead apparently using the flowers as mating platforms.

Male Trichostetha curlei in its natural habitat on the Elandsberg summit, November 2013. Jonathan Ball in Perissinotto et al. (2014).

The species was found living on arid quartzite fynbos in the Elandsberg Range at altitudes of about 1500 m above sea level. This comprises mostly medium density tall shrubs, comprising Asters, Proteas, Ericas and Restioids. Most of the plants are derived from the Fynbos Biome, though some elements are associated with the  Succulent Karoo Biome.

Typical habitat of Trichostetha curlei on the southern slope of the Elandsberg range. Renzo Perissinotto in Perissinotto et al. (2014).

See also…

Scavenger Scarab Beetles (Hybosoridae) are small (5-7 mm), oval Scarab Beetles, with enlarged mandibles and mouthparts. They are typically carrion feeders, with some species favouring vertebrate dung. They are not a large group of Beetles, with only about 600...

Bumble Bee Scarab Beetles (Glaphyridae) are small, brightly coloured Scarab Beetles; they are active animals, and frequently resemble Bumble Bees when in flight. There are eight extant genera in the family, two of which have fossil records. Another two genera are known from the fossil record only. The fossil record of the family dates...

Scarabs of the Tribe Corythoderini are small Beetles found living in the nests of Termites, found across much of Africa and south Asia. They are tolerated by the Termites, and apparently produce secretions which the Termites use in some way, though the relationship is not well understood.

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