Micrarchus hystriculeus
Species of insect
From Wikipedia, the free encyclopedia
Micrarchus hystriculeus is a species of flightless stick insect (order Phasmatodea) in the family Phasmatidae,[1] and is endemic to New Zealand.[2] It was first described by John Obadiah Westwood in 1859.[3] It is a widespread species of the genus Micrarchus and the only species recorded on North Island.[4] This species is known for its sexual size dimorphism,[5] prolonged mating behaviour,[2] and male-biased sex ratio.[6] It is currently classified as Not Threatened under the New Zealand Threat Classification System.[3]
| Micrarchus hystriculeus | |
|---|---|
| |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Class: | Insecta |
| Order: | Phasmatodea |
| Family: | Phasmatidae |
| Genus: | Micrarchus |
| Species: | M. hystriculeus |
| Binomial name | |
| Micrarchus hystriculeus (Westwood, 1859) | |
Description
Micrarchus hystriculeus is apterous (wingless) and exhibit sexual size dimorphism.[5] Adult females are larger than males, exceeding 56 mm in length,[7] with proportionally longer mid and hind legs, which support their larger abdomens.[5] Males are less than 50 mm in length,[7] and are equipped with elongate tong-like claspers armed with a series of black teeth, used to grasp females during copulation.[7] This species is generally small, brown in colour with two rows of spines on their backs and spiky flangers on legs. Their eggs are distinctive and used for species identification.[1][8] Eggs have spine-like setae absent and the capsules are 1.7–2.4 times longer than broad.[7] They have a prominent keel arising steeply and a capitulum (knob-like structure) that is very short, flatly conical, and sharply pointed.[1][7]
Identification features:
Female[7]
- Cerci distinctly shorter than the anal segment, not reaching the tip of the anal segment
- Metatarsals of the mid and hind limbs lacking a dorsal lobe
- Operculum extending up to halfway along the anal segment
Males[7]
Distribution and habitat
This species is widely distributed throughout New Zealand,[2] and is the only member of its genus found on the North Island.[4] It inhabits lowland arboreal habitats and is considered an ecological generalist.[4] Although this species is present in alpine areas, it is less cold-hardy compared to other Micrarchus species.[9]
Biology and ecology
Micrarchus hystriculeus is a plant-feeding stick insect,[5] known to feed on mānuka, ribbonwood and Hoheria.[10] Mating occurs when the male mounts the back of the female and curves his abdomen down and around the female's body, tightly grasping the operculum.[5] This species exhibits prolonged pairing which is thought to function as mate guarding.[11][5] Males compete in grappling contests where males attempt to dislodge males that are mounted on females.[5] Populations have male-biased sex ratio, with unpaired females rarely observed.[6]
Physiological research indicates that this species can survive low temperatures by supercooling but is not entirely freeze tolerant.[9] Compared to the alpine species, this lowland species has a significantly low (<50%) survival rate when ice is present.[9] This species uses a cold tolerance strategy called freeze avoidance, avoiding the internal formation of ice.[9]
Taxonomy and phylogeny
This species name is derived from the Latin word "hystriculeus," meaning “bristly” or "spiny," referring to the insect's spiny body.[7] First described by Westwood in 1859, this species belongs to the order Phasmatodea and is in the family Phasmatidae.[3] The genus Micrarchus contains several species, including an undescribed taxon from the northern area of the South Island of New Zealand, some of which are restricted to alpine habitats.[4]
Molecular phylogenetic analyses show that New Zealand stick insects, including Micrarchus, form a monophyletic radiation derived from a single colonisation event from New Caledonia.[12] Further studies confirmed that all New Zealand Phasmatidae are closely related to each other and to the New Caledonia species.[12]