Endangered Species 2010 Series main post.
Arthropods (animals of the Phylum Arthropoda) are an extremely diverse group readily identified by their chitinous exoskeleton, multiple joined appendages, and segmented bodies. Early estimates of arthropod diversity (known and unknown) ranged as high as 30-100 million. That figure has since been dramatically revised and conservative estimates put the number of extant species at between 2 and 10 million, only just over one million of which have been described. These one million species account for over 80% of all extant animal species. Arthropods inhabit almost every habitat, from the deep ocean to extreme altitudes; from Arctic ice packs to the Australian deserts. Unfortunately, global habitat degradation and destruction continues apace and it is inevitable that a great many species will be, and indeed have been lost before they could be discovered.
It should be noted that a great many arthropod species are data deficient and thus are unclassified (that is to say, except as ‘data deficient’ (DD)). It is highly probable that a great many of these species are critically endangered.
Follow the link for ‘Arthropods Part 1 – Arachnids, Crustaceans and Millipedes‘.
[1] Understanding Evolution. (2010). The Arthropod Story. University of California Museum of Paleontology. [online]
[2] Odegaard, F. (2000). How many species of arthropods? Erwin’s estimate revised. Biol J Linn Soc. 71:583 – 597. [available online]
[3] Hamilton, A. et al. (2010). Quantifying uncertainty in estimation of tropical arthropod species richness. Am Nat. 176: 90 – 95
[4] Insects.org [online]
Delta green ground beetle (Elaphrus viridis)
This Californian beetle exhibits a life history which is in synchrony with vernal pool habitats, specifically those of California. These pools occur in areas of poor drainage and fill with water during the winter rains. Emergence and dormancy in the beetle are cued by the filling and subsequent drying of these pools. Agricultural development and urban encroachment has eliminated or degraded much of this habitat and mat-forming invasive plants restrict foraging. There are several fragmented sub-populations restricted to Solano County, though most occur on private land and require negotiated protection.
[1]World Conservation Monitoring Centre (1996). Elaphrus viridis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2
[2] Essig Museum of Entomology (2010). Delta Green Ground Beetle (Coleoptera: Carabidae). Essig Museum of Entomology, U.C. Bereley. [online]
Image © Doug Wirtz
Pygmy Hog-Sucking Louse (Haematopinus oliveri)
Lice are ectoparasites, variously feeding on the skin, debris, blood and sebaceous secretions of the host organism. The majority of louse species are host-specific, that is, they are only capable of surviving on a single species. H. oliveri is such a species, residing on and migrating between the bodies of the pygmy hogs (Porcula salvania) of India. Thus the fates of the lice are inexorably linked to those of their porcine hosts. Unfortunately, due to habitat destruction and degradation, agricultural activities and human encroachment, there are fewer than 250 mature pygmy hogs surviving in the wild.
Note: The species in the image is not H. oliveri, but H. suis, the hog louse.
[1] World Conservation Monitoring Centre (1996). Haematopinus oliveri. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
[2] Narayan, G., Deka, P. & Oliver, W. 2008. Porcula salvania. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2
Image © Stanley Dean Rider Jr.
Franklin’s bumblebee (Bombus franklini)
Franklin’s bumblebee is described as having possibly the most limited distribution of any bumblebee species in the world; certainly of those inhabiting North America. Its range encompasses a rough oval of 305km (North to South) x 70km (East to West) between Oregon and California. Fairly common in 1998, numbers declined so dramatically that just 6 years later, in 2004, none were observed. One individual was found in 2006. Threats include habitat loss, pesticides and pollution and exotic diseases from introduced commercial hives.
[1] Kevan, P.G. (2008). Bombus franklini. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2
[2] Thorp, R. W. (2005). Species profile: Bombus franklini. In: Red List of Pollinator Insects of North America. Shepher, M. D., Vaughan, D. M., Black, S. H. (eds). Portland, OR: The Xerces Society for Invertebrate Conservation. [available online]
Image © Robbin Thorp
Cromwell chafer (Prodontria lewisi)
The Cromwell chafer is a scarab beetle endemic to New Zealand. As the common name attests, it is found in Cromwell, Otago; or, to be more specific, in an 81 hectare reserve (the Cromwell Chafer Beetle Nature Reserve) between Bannockburn and Cromwell. Four sub-populations are known to exist within the reserve, associated with wind-blown sand dunes, cushion plant (Raoulia australis) and silver tussock (Poa cita). The species is threatened by habitat degradation and predation by introduced species and the little owl. (Athene noctua) Curiously, large areas of apparently favourable habitat remain uninhabited, suggesting that the limiting factors are poorly understood.
[1] World Conservation Monitoring Centre (1996). Prodontria lewisi. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
[2] Ferreira, S. M., McKinlay, B. (1999) Conservation monitoring of the Cromwell chafer beetle (Prodontria lewisii) between 1986 and 1997. Science for Conservation 123. Department of Conservation, Wellington, N.Z. [available online]
[3] Watt, J. C. (1979). Conservation of the Cromwell chafer Prodontria lewisi (Coleoptera: Scarabaeidae). New Zealand Journal of Ecology. 2: 22 – 29 [available online]
Image © Bruce McKinlay
Frigate Island giant tenebrionid beetle (Polposipus herculeanus)
Tenebrionids, otherwise known as darkling beetles, are a globally distributed family of over 20,000 species. They are all herbivorous/detrivorous, consuming fresh and decaying vegetation. P. herculeanus is the largest of the tenebrionids, attaining a length of up to 30mm. When alarmed, the beetle secretes a musky chemical which also stains the skin purple. Being restricted to Frégate Island in the Seychelles, the species has a range of just 2.19 km^2. The species proved resilient to the arrival of humans and brown rats on the island. However, the beetle is particularly associated with the sanddragon tree (Pterocarpus indicus) which is currently being affected by a fungal disease. As with all similarly restricted species, the beetle is also vulnerable to the effects of invasive species and natural disasters.
[1] World Conservation Monitoring Centre (1996). Polposipus herculeanus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2
[2] ARKive.org. (2010). Frigate Island giant tenebrionid beetle (Polposipus herculeanus). ARKive.org. [online]
Saint Helena earwig (Labidura herculeana)
The St. Helena earwig is the only one of more than 1,800 described earwig (Dermaptera) species to be listed on the IUCN Red List. It is also the largest of the earwigs, measuring up to 83mm in length. The species is endemic to the island of St. Helena in the South Atlantic (an area of roughly 122 km^2) where it typically inhabits gumwood forests and seabird colonies. Originally described in 1798, it was not collected again until 1913. Recent surveys failed to find nymphs or fossil cerci (the paired rear appendages) and it is feared that the clearing of the gumwood forest coupled with the impact of an introduced centipede (Scolopendra morsitans) may have driven the species to extinction.
[1] World Conservation Monitoring Centre (1996). Labidura herculeana. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
[2] Haas. F. (2009). The giant earwig of St. Helena – the dodo of the dermaptera. Earwig Research Centre. [online]
Image © Takeshi Yamada
Trithemis nigra
A species of dragonfly endemic to Sáo Tomé and Príncipe where it probably inhabits rainforest streams. It has a range of occurrence no larger than 50km^2 and is threatened by habitat loss. At least half of the island (139km^2 area) has been deforested.
Note: The species in the image is T. annulata, not T. nigra.
[1] Dijkstra, K.-D.B. (2006). Trithemis nigra. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
Image © Cor Zonneveld
Dracula ant (Adetomyrma venatrix)
The dramatically named dracula ants of Madagascar are a relatively recent discovery; the first individuals were described in 1994 and a colony was not discovered until 2001. They are considered to be a primitive ant species, representing the link between modern ants and a hymenopteran wasp ancestor. This link is borne out by the number of joints between thorax and abdomen (one as opposed to two or three in other ants). Their curious method of feeding whereby they consume the hemolymph (‘blood’) of their own larvae via incision in a non-lethal manner may be a precursor to trophallaxis (passing food from mouth/anus to mouth) in modern ants. Habitat loss is a significant threat to the majority of Madagascan wildlife. It has been posited that this particular species may be extinct within ten years.
[1] Social Insects Specialist Group (1996). Adetomyrma venatrix. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
[2] Ward, P. S. (1994). Adetomyrma, an enigmatic new ant genus from Madagascar (Hymenoptera: Formicidae), and its implications for ant phylogeny. Systematic Entomology 19: 159–175. [available online]
[3] ARKive.org (2010). Dracula ants (Adetomyrma venatrix). ARKive.org. [online]
Image © Alex Wild
Piedmont Anomalous Blue (Polyommatus humedasae)
Endemic to the Valle d’Aosta in the Italian Alps, this butterfly exists in three fragmented sub-populations within an area of less than 10km^2. The population continues to decline; reductions of between 6 and 30% have been reported. The isolated nature of the preferred habitat means that there are few opportunities for dispersal, meaning that the species is highly unlikely to colonise other favourable areas. It is possible that there are a few thousand individuals remaining. Invasive plants and habitat alteration (here in the form of natural succession) are the primary threats. Collection for international trade could also be an issue despite restrictions on such activities at the main site.
[1] van Swaay, C., Wynhoff, I., Verovnik, R., Wiemers, M., López Munguira, M., Maes, D., Sasic, M., Verstrael, T., Warren, M. & Settele, J. (2009). Polyommatus humedasae. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2
[2] Balletto, E. (1993). Polyommatus humedasae (Toso & Balletto). In: Conservation Biology of Lycaenidae (Butterflies). New, T. R. (ed). p. 88 – 89. [available online via Google books]
Image © Matt Rowlings
Land lobster (Dryococelus australis)
D. australis exists on the Lord Howe Island group, 600km off the eastern coast of Australia in the Tasman Sea. They are large, heavy-bodied stick insects. The species was believed to have become extinct in the 1920′s after rats were introduced to the largest landmass in the group, Lord Howe Island. In 2001, a population was discovered on Ball’s Pyramid, a 1844 feet tall volcanic stack some 23km from Lord Howe Island. The insects were found under a single shrub; their current population is unknown though it is unlikely that there are more than 30 individuals. The captive population – borne of two pairs removed from Ball’s Pyramid – numbers in excess of 450 individuals, 20 of which have been returned to a protected zone on Lord Howe Island.
[1] ANZECC Endangered Fauna Network (2002). Dryococelus australis. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2.
[2] Priddel, D. (N/K). The Lord Howe Island phasmid: an extinct species reborn. Foundation for National Parks and Wildlife. [online]
[3] Department of the Environment, Water, Heritage and the Arts (2010). Dryococelus australis. In: Species Profile and Threats Database, Department of the Environment, Water, Heritage and the Arts, Canberra. [online]
Rhinocypha ogasawarensis
The Ogasawara Islands, also known as the Bonin Islands, are a 30-strong archipelago 1,000km South of Tokyo, Japan. A relatively large proportion of the species which inhabit these islands are endemic. Many are included on the IUCN Red List as a result of habitat destruction and the impacts of invasive species. R. ogasawarensis is one of five odonates (dragonflies and damselflies) endemic to the islands. It has seen its range reduce as suitable aquatic habitat has been destroyed or polluted. Predation by birds and the invasive lizard Anolis carolinensis (the Carolina anole) may also be problematic.
Note: The species in the image, while of the genus Rhinocypha, is not R. ogasawarensis.
