Megadromus speciosus is a species of ground beetle (family Carabidae), endemic to New Zealand and of high conservation interest.[1]
| Megadromus speciosus | |
|---|---|
| |
| Megadromus speciosus found in Marlborough, New Zealand | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Family: | Carabidae |
| Genus: | Megadromus |
| Species: | M. speciosus
|
| Binomial name | |
| Megadromus speciosus Johns, 2007
| |
| |
| Observations of Megadromus speciosus from iNaturalist (as of August, 2024). | |
Distribution and habitat
editMegadromus speciosus (Picton ground beetle) is found in just a few forest remnants, in northern South Island New Zealand.[1][2] The species is typically found under stones and logs, and in areas with deep leaf litter.[2] The habitat is heavily influenced by the presence of wild pigs, which have caused extensive damage to the soil surface and understorey vegetation, particularly at Port Underwood.[2] The species also shows a preference for undisturbed native vegetation.[2] As of 2010 Megadromus speciosus has the conservation status of 'relic' in the category 'At Risk' in the NZTCS.[3]
The species is confined to isolated populations in the Marlborough Sounds, northern South Island, New Zealand.[2] Specifically, it is found at Port Underwood Saddle and Arapawa Island.[2] The Arapawa Island population appears to be more secure, while the Port Underwood population is under threat from habitat degradation.[2] A historical report suggested the presence of the species on Blumine Island, but this was not confirmed in recent surveys.[2] Niche modelling used to study the distribution of this genus found that 50% of the predicted range of Megadromus speciosus is within the New Zealand protected areas network.[4]
Morphology
editMegadromus speciosus is described as a large, stout-bodied beetle with a length of 23-26 mm.[2] The dorsal surface of the head and pronotum is greenish, while the elytra have a coppery-purple sheen.[2] Male genitalia are distinct, with an enlarged mesotibia and a forked left paramere.[2] The morphological conservatism within the genus makes species identification challenging without examining genitalia.[2]
Taxonomy
editMegadromus speciosus was described in 2007 by Peter Johns from specimens collected from Nothofagus forest near Picton (Port Underwood).[1] The genus Megadromus is part of the Carabidae family, which comprises large, flightless beetles.[2]
Genetic analysis of mitochondrial DNA sequences (COI and ND1 genes), show that M. speciosus is distinct from other related species, with significant sequence divergence.[2]
Conservation status
editMegadromus speciosus is classified as range-restricted and conservation-dependent under the New Zealand threat classification system.[1][2] The species is formally protected under the Wildlife Amendment Act (1980) and has been included in various conservation ranking systems due to its vulnerability to habitat modification and introduced predators.[2]
The primary threat to Megadromus speciosus is habitat degradation caused by wild pigs, especially at Port Underwood Saddle.[2] The pigs have extensively damaged the soil surface and understorey vegetation, which are critical for the species' survival.[2]
References
edit- ^ a b c d Johns, Peter Malcolm (2007). "New Genera and Species of Rare New Zealand Endemic Carabids. (Coleoptera: Carabidae)". Privately Published.
- ^ a b c d e f g h i j k l m n o p q r Pawson, Stephen M.; Armstrong, Karen F. (February 2007). "A morphological and molecular comparison of island and mainland populations of Megadromus speciosus (Coleoptera: Carabidae) from the Marlborough Sounds, New Zealand". New Zealand Entomologist. 30 (1): 13–23. Bibcode:2007NZEnt..30...13P. doi:10.1080/00779962.2007.9722147. ISSN 0077-9962.
- ^ "NZTCS". nztcs.org.nz. Retrieved 2024-08-31.
- ^ Fuller, Lauren; Johns, Peter M.; Ewers, Robert M. (2013). "Assessment of protected area coverage of threatened ground beetles (Coleoptera: Carabidae): a new analysis for New Zealand". New Zealand Journal of Ecology. 37 (2): 184–192. ISSN 0110-6465.