Mecodema howittii is a species of ground beetle that occurs in New Zealand. It is only found in Banks Peninsula in the Canterbury region, and is the largest of the endemic carabids found on the peninsula. Because of a significant reduction in its distribution, it is considered to be a declining species. M. howittii is most commonly found underneath logs during the spring and summer, primarily in forest and grassland habitats including pasture. The species is nocturnal and known to prey on other invertebrates.
| Mecodema howittii | |
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Scientific classification 
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| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Adephaga |
| Family: | Carabidae |
| Genus: | Mecodema |
| Species: | M. howittii
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| Binomial name | |
| Mecodema howittii Laporte de Castelnau, 1867
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| Synonyms | |
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Taxonomy
editThis species was originally described in 1867 by Francis de Castelnau from a specimen collected near Christchurch. The specific name refers to the collector, Australian entomologist Godfrey Howitt, and de Castelnau noted it was the largest Mecodema species he had encountered.[1] Although the specific epithet chosen by de Castelnau was Howittii, later entomologists have often referred to it as M. howitti,[2][3][4] though in Larochelle and Larivière's catalogue of the New Zealand Caribidae it is correctly named as howittii.[5] The type specimen is stored in the Genoa Museum in Italy.[2] This species was described again just a year later by Jules Putzeys as Mecodema rectolineatum, and then again as Mecodema walkeri in 1904 by Thomas Broun.[6][7] These species names were later synonymised in 1874 and 1949 respectively.[8][2] The species was most recently given an updated description by Britton in 1949, who assigned it to the costellum species group.[2]
Description
edit
M. howittii is the largest of the 10 endemic ground beetle species that can be found in Banks Peninsula, measuring 26–31 mm (1.02–1.22 in) in length.[3] Similar in appearance to other Mecodema, this species can be distinguished by the structure of the elytra (hardened forewings that make the upper surface of the abdomen) and the presence or absence of setiferous punctures (depressions in the body with a hair in them).[2]
The overall body colour is black. The vertex of the head (upper surface of the head) has a smooth texture with a depression and faint (or in some cases absent) punctures. The base of the labium (mouthpart appendage) has three punctures on either side. The margins of the pronotum (first upper segment of the thorax) have ten to twelve punctures on the lateral margin. The third and fifth elytral intervals (raised stripes of the elytra) are flattened, the second, fourth, sixth and eighth intervals are smooth with two rows of punctures each, and the first, third and seventh intervals are smooth with fine wrinkles.[2]
Distribution and habitat
editM. howittii is endemic to Banks Peninsula in the Canterbury region of the South Island. The species is only known to occur in the central and eastern parts of the peninsula at both lowland and higher altitudes.[3] Historical records indicate it used to occur as far west as the Port Hills, but by the 1980s had disappeared from there. It is possible this range contraction is due to extensive nineteenth-century deforestation of the peninsula and predation by introduced mammals such as rats and mice.[9]
This species occurs in podocarp and hardwood forest remnants as well as grasslands, even in heavily modified habitats such as pastures.[3][5] Although it has been proposed that populations in pastures are relicts that persist in microhabitats supported by logs. The presence of this species is also strongly associated with high levels of ground level vegetation, which form favourable microhabitats.[3] This burrowing species is associated with fallen logs it hides under, presumably once in podocarp forest, and it is more common in areas with more logs and less disturbance.[3][4] Although it was once very common in high ridges where forest had been cleared and logs left to lie in pasture, it disappears when the logs rot away or are burned.[9]
Life history
editM. howittii is most active during spring and summer months (when it apparently breeds), being most frequently seen in November. Gravid females have been observed from December to January.[4] This is a common activity pattern for other Banks Peninsula carabids.[4]
Behaviour
editThese beetles are nocturnal, but can be seen during the day in some conditions.[4][5] Like most carabids, they are active predators, observed preying on the larvae of the carabid Holcaspis suteri, crane flies, and (in captivity) the mealworm Tenebrio molitor.[10] They are slow runners and thought to be less active when soil temperatures are below 6.5°C.[4][5] Like other Mecodema, they are flightless and live in burrows or hollows under logs and rocks.[3]
Predators and parasites
editThe native predators of M. howittii are presumed to include large species of spider and birds such as morepork and weka (although the latter is no longer present on the peninsula).[10] They are probably preyed upon by introduced mammals.[3] An undescribed species of mite from the genus Micromegistus has been associated with M. howittii; these mites primarily latch onto the pronotal and metasternum areas (parts of the thorax), but are most common around the coxae (the base of the legs).[10]
Conservation status
editUnder the New Zealand Threat Classification System, this species is listed as "Declining" with the qualifiers of "Range Restricted" and "Sparse".[11] It has a fragmented range in eastern and central Banks Peninsula, which may still be contracting. It has been suggested that the decline of M. howittii is due to factors such as poor dispersal abilities, introduced mammalian predators and loss of habitat for livestock grazing.[3]
External links
editReferences
edit- ^ Laporte de Castelnau, F L (1867). "Notes on Australian Coleoptera Part II". Transactions and Proceedings of the Royal Society of Victoria. 8: 159–160.
- ^ a b c d e f Britton, E.B. (1949). "The Carabidae (Coleoptera) of New Zealand Part III - A revision of the Broscini". Transactions of the Royal Society of New Zealand. 77 (4): 533–581.
- ^ a b c d e f g h i Anderson, S J; Emberson, R M; Brown, B (2003). "Distribution and conservation requirements of Mecodema howitti Castelnau (Coleoptera: Carabidae: Broscini)". New Zealand Entomologist. 26 (1): 45–52. doi:10.1080/00779962.2003.9722107. ISSN 0077-9962.
- ^ a b c d e f Anderson, S. J.; Brown, B.; Emberson, R. M. (2004). "Seasonal activity and habitat associations of Mecodema howitti and Megadromus guerinii, two endemic New Zealand ground beetles (Coleoptera: Carabidae)". New Zealand Journal of Zoology. 31 (4): 305–312. doi:10.1080/03014223.2004.9518383. S2CID 84551722.
- ^ a b c d Larochelle, A; Larivière, M-C (2001). "Carabidae (Insecta: Coleoptera): catalogue". Fauna of New Zealand. 43. doi:10.7931/J2/FNZ.43. ISSN 1179-7193.
- ^ Putzeys, J (1868). "Les broscides". Stettiner Entomologische Zeitung. 29: 317–318.
- ^ Broun, T (1904). "Descriptions of new genera and species of New Zealand Coleoptera". Annals and Magazine of Natural History. 12: 43–44.
- ^ Bates, H W (1874). "On the geodephagous Coleoptera of New Zealand". Annals and Magazine of Natural History. 4: 236.
- ^ a b Peter M. Johns (August 1986), Arthropods of Banks Peninsula Reserves, Christchurch: University of Canterbury School of Biological Sciences, Wikidata Q135855974
- ^ a b c Anderson, S. J. (2000). Distribution, Habitat Associations, and Activity Patterns of Two Endemic Banks Peninsula Carabid Beetles, Mecodema howitti and Megadromus guerinii (Phd). Lincoln University.
- ^ Leschen, R A B; Marris, J W M; Emberson, R M; Nunn, J.; Hitchmough, R A; Stringer, I (1 July 2012). "The conservation status of New Zealand Coleoptera". New Zealand Entomologist. 35 (2): 91–98. doi:10.1080/00779962.2012.686311. ISSN 0077-9962.