Brachaspis robustus
| Robust grasshopper | |
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| A female Brachaspis robustus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Clade: | Euarthropoda |
| Class: | Insecta |
| Order: | Orthoptera |
| Family: | Acrididae |
| Genus: |
Brachaspis Hutton, 1898 |
| Species: | B. robustus |
| Binomial name | |
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Brachaspis robustus Bigelow, 1967 |
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| The distribution of B. robustus in New Zealand | |
Brachaspis robustus is a nationally endangered species of grasshopper endemic to the Mackenzie Basin of the South Island of New Zealand. The genus Brachaspis is endemic to the South Island of New Zealand.
As early as the 1960s, this species was noted as rare and in need of conservation action. In 1993, it was estimated that there were only approximately 800 adults in the wild. By the end of 2009/2010 summer it was estimated that this had declined to approximately 600 adults. Whereby in 1993, most adults were found in three key very large populations and only a few sub-populations, by 2010, numerous new sub-populations have been discover, however, the three key populations from 1993 are now very sparse and made up of numerous sub-populations.
Two species of grasshoppers are listed for protection under the Wildlife Act 1953 of New Zealand this include B. robustus and Sigaus childi.Sigaus takahe is also protection under the Wildlife Act 1953 indirectly as it is only known from the Murchison Mountains Specially Protected (Takahē) Area.
B. robustus is a highly visually cryptic species, often relying on visual crypsis as passive defense against predation. It is also sexually dimorphic; adult males have a body length of 18–22 mm (0.71–0.87 in.) and adult females have a body length of 38–42 mm (1.5–1.7 in.). Males are estimated to have 5 instars and females are estimated to have 6 instars, the same as several other sub-alpine and alpine grasshopper species within New Zealand. The wings on B. robustus are micropterous (small wings) between 1–2 millimetres (0.039–0.079 in) making this species flightless like most of New Zealand grasshoppers. There are three known colour morphs for adult B. robustus, 'Grey', 'Orange' and 'Black'. The most common colour morph is 'Grey' at approximately 60% of adult B. robustus, next is the colour morph 'Orange' at 40% and the very rare colour morph 'Black' at less than 0.5%.
Colour morphs 'Grey'.
Colour morphs 'Orange'.
Colour morphs 'Black'.
B. robustus is only known from the Tekapo, Pukaki and Ohau river catchments in the Mackenzie Basin. It can be found as far south as Lake Benmore (44°20′29″S 170°12′42″E) and as far north as the upper Fork Stream (43°58′24″S 170°24′04″E). The altitudinal distribution of Brachaspis robustus is between 352 m (1,155 ft) on the lower Ohau River and 1,060 m (3,480 ft) the upper Fork Stream. Detailed searches since 1980 have been carried out throughout the Mackenzie Basin and a good understanding of its current distribution is now known.
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Wikipedia