J Insect Conserv DOI 10.1007/s10841-014-9660-6 ORIGINAL PAPER Prioritizing non-marine invertebrate taxa for Red Listing Justin Gerlach • Michael J. Samways • Axel Hochkirch • Mary Seddon • Pedro Cardoso • Viola Clausnitzer • Neil Cumberlidge • B. A. Daniel • Scott Hoffman Black • Ju¨rgen Ott • Paul H. Williams Received: 16 December 2013 / Accepted: 20 June 2014 Ó Springer International Publishing Switzerland 2014 Abstract The IUCN Red List of threatened species is and Onycophora. Of these, the high-level taxa that emerge biased towards vertebrate animals, a major limitation on its as highest priorities are Odonata (dragonflies and damsel- utility for overall biodiversity assessment. There is a need flies), Araneae (spiders), Mantophasmatodea (heelwalkers), to increase the representation of invertebrates (currently Plecoptera (stoneflies), non-marine Mollusca (Bivalvia and 21 % of species assessed on the List; \1 % of all inver- Gastropoda), Trichoptera (caddisflies), Coleoptera (bee- tebrates). A prioritisation system of terrestrial and fresh- tles), Lepidoptera (moths and butterflies), Oligochaetes water groups is presented here, categorising taxa by species (earthworms), Orthoptera (grasshoppers and crickets), richness, assessment practicality, value for human land use Decapoda (crayfish, crabs, shrimps) and Diptera (flies). Of and bioindication, and potential to act as conservation these Red Listing is well advanced for Decapoda, fresh- flagships. 25 major taxonomic groupings were identified as water Mollusca and Odonata. This leaves eight higher taxa priorities, including the Annelida, Arthropoda, Mollusca, with currently a minimum or patchy Red List assessment coverage. We recommend that Red List assessments in J. Gerlach (&) N. Cumberlidge Coordinator – Terrestrial and Freshwater Invertebrate Red List Chair – Freshwater Crab and Crayfish SG, Department of Authority, 133 Cherry Hinton Road, Cambridge CB1 7BX, UK Biology, Northern Michigan University, Marquette, e-mail: [email protected] MI 49855-5376, USA M. J. Samways B. A. Daniel Member Emeritus – Invertebrate Conservation Sub-Committee, Co-Chair – South Asian Invertebrate SG, Zoo Outreach Department of Conservation Ecology and Entomology, Centre Organisation, Villankurichi PO, for Agricultural Biodiversity, Stellenbosch University, P.O. Box 5912, Coimbatore 641035, Tamil Nadu, India Private Bag X1, Matieland 7602, South Africa S. H. Black A. Hochkirch Deputy Chair – Invertebrate Conservation Sub-Committee, Chair – Invertebrate Conservation Sub-Committee, Chair – Butterfly SG, The Xerces Society for Invertebrate Chair – Grasshopper SG, Department of Biogeography, Conservation, 628 NE Broadway, Suite 200, Portland, Trier University, Universita¨tsring 15, 54286 Trier, Germany OR 97232, USA M. Seddon J. Ott Chair – Mollusc SG, Glebe House Cottage, Exbourne, European Invertebrate Specialist Advisor – L.U.P.O. GmbH, Okehampton, Devon EX20 3RD, UK Friedhofstr. 28, 67705 Trippstadt, Germany P. Cardoso P. H. Williams Chair – Spider SG, Finnish Museum of Natural History, Chair – Bumblebee SG, Department of Life Sciences, Natural Pohjoinen Rautatiekatu 13, PO Box 17, 00014 Helsinki, Finland History Museum, Cromwell Road, London SW7 5BD, UK V. Clausnitzer Chair – Dragonfly SG, Senckenberg Museum of Natural History Goerlitz, PF 300154, 02806 Go¨rlitz, Germany 123 J Insect Conserv future focus on these groups, as well as completion of play major roles in ecosystems, notably fungi and many assessments for terrestrial Molluscs and Odonata. How- invertebrate groups (Koh et al. 2004; Thomas et al. 2004; ever, we also recommend realism, and as some of groups Dunn 2005). The importance of invertebrates is highlighted are very large, it will be necessary to focus on subsets such by the case of pollinators, where there have been declines as certain functionally important or charismatic taxa or on in populations of some of the most significant pollinators a sampled subset which is representative of a larger taxon. (Biesmeijer et al. 2006; Cameron et al. 2011; Williams and Osborne, 2009; Gill et al. 2012), with evidence of a cor- Keywords Conservation status Á Strategic planning Á responding decline in the abundance of insect pollinated Conservation planning Á Biodiversity Á Extinction plants (Biesmeijer et al. 2006). Conservation of other invertebrates with important ecological and economic functions (pollinators, water filterers, soil formers, bio- Introduction control species etc.) is potentially of great economic as well as ecological value. Yet determining these values is Current rates of species extinction are estimated to be currently hampered by a lack of available information on 48–476 times the background rate (Baillie et al. 2004), with the status of most species. some taxa having considerably higher rates (e.g. amphibi- In 2010, the ‘Barometer of Life’ (BoL) was proposed ans—McCallum 2007). These estimates are imprecise (Stuart et al. 2010) to provide an overview of the status of owing to major problems with the data (Stork 2009). biodiversity, free from data biases. This aims to monitor Firstly, there are no clear consensus estimates of the the status of 160,000 species, selected across various taxa, number of extant species, with estimates varying from 1.8 including a provisional target of 45,344 invertebrates. The to 111.7 million (Wilson 1987; Mora et al. 2011; Costello biases to be avoided by the BoL are primarily taxonomic et al. 2012). Identifying extinctions with certainty is diffi- (principally the dominance of vertebrate assessments), but cult (Roberts 2006; McKelvey et al. 2008), and the esti- also include biases towards certain geographical areas and mates are questionable even for some well studied, low ecosystems. Ideally the listing would be representative of diversity taxa such as birds (Pimm et al. 2006). Methods of all taxa, regions and systems. Some attempts have been extrapolating extinction rates from existing data such as made to reduce biases through comprehensive listing of rates of habitat loss are also contentious (Stork 2009;He some major groups (mammals, birds, amphibians, corals, and Hubbel 2011; Evans et al. 2011). With little idea of the sharks, cycads), major groups in selected ecosystems rate of extinction, it is not surprising that the levels of (dragonflies, freshwater fish, freshwater molluscs, fresh- threat to the surviving species are even more uncertain. water crabs, freshwater shrimps, and crayfish), sampled Currently, the International Union for the Conservation of listings (reptiles, butterflies, dung beetles) and geographi- Nature (IUCN) Red List of threatened species (IUCN 2013) cal listings (e.g. European saproxylic beetles). However, contains assessments of the status of 71,576 species. This even these are restricted taxonomically, ecologically and/or represents only 4 % of described species and 0.9 % of all geographically. In addition to these assessment projects species [using Mora et al.’s (2011) estimate], and is strongly coordinated by IUCN and its Red List partners, assess- biased towards vertebrates (52 % of assessed species). ments are added to the Red List by submission of small The Sampled Red List Index (SRLI) is an established numbers of assessments by individual experts. methodology which aims to quantify the state of global Current trends in assessment rate mean that the BoL biodiversity using a sampled subset of species from dif- target would not be reached for at least 200 years, therefore ferent taxa (Baillie et al. 2008). It provides a means of additional larger-scale (taxonomic and geographical) evaluating threat in less well studied groups, and is com- assessments are needed. This requires determining which pleted for dragonflies (Clausnitzer et al. 2009) freshwater invertebrate groups should be the focus for comprehensive crabs and crayfish (Cumberlidge et al. 2009), freshwater or sampled assessments. This is particularly important molluscs. Butterflies are currently being assessed for the where significant funding needs to be sought for assess- SRLI (Lewis and Senior 2011). European saproxylic bee- ment. As noted by Stuart et al. (2010), some taxa such as tles have also been assessed, although not sampled ran- nematodes and sponges are generally too poorly known domly (Nieto and Alexander 2010), and assessment is taxonomically to allow meaningful assessment, except in almost completed for freshwater molluscs. This is one way specific geographical areas on a particular taxonomic of attempting to assess speciose groups, especially given subset. This means that selection of the 45,344 invertebrate the relative paucity of invertebrate assessments contribut- species cannot be merely an ad hoc process, as this might ing to the Red List (Cardoso et al. 2011b). lead to the creation of yet more biased data sets. Instead, a Some of the groups which are currently under-repre- system of prioritisation is needed. Prioritisation of non- sented on the Red List are of particular concern as they marine invertebrate groups was undertaken by the 123 J Insect Conserv Table 1 Diversity of non-marine invertebrates and their Red List Table 1 continued status (version 2013.2) Described RL Out of Described RL Out of speciesa speciesb date speciesa speciesb date Diptera 156,774 7 7 Porifera 150 0 0 Mecoptera 400 0 0 Cnidaria 100 0 0 Siphonaptera 2,082 0 0 Myxozoa 3 0 0 Trichoptera 14,548 4 4 Platyhelminthes 7,500 1 1 Lepidoptera 158,396 722 265 Micrognathozoa 1 0 0 Hymenoptera 153,088 302 151 Entoprocta 2 0 0 a Derived from Chapman (2009), Mayer and