Category: Lepidoptera

Background

Until 2022, Catalogue of Life (COL) and GBIF still relied on the NHM LepIndex dataset for names for almost all Lepidoptera (butterflies and moths). This is now superseded by a revised version of LepIndex maintained in TaxonWorks as the Global Lepidoptera Index (GLI). See this earlier post for more detail.

Methods

The concept used in LepIndex for the gelechioid family Elachistidae corresponded to what we now treat as a subfamily Elachistinae. At the time of its last import into COL, LepIndex had 491 scientific names associated with this (sub-)family, organised as follows:

• Family – 1 accepted
• Genus – 35 accepted
• Species – 410 accepted, 1 provisionally accepted, 40 synonyms, 2 ambiguous synonyms
• Subspecies – 2 accepted

In 2019, Lauri Kaila published An annotated catalogue of Elachistinae of the World (Lepidoptera: Gelechioidea: Elachistidae) in Zootaxa. I had already brought GLI up to date for the Australian Elachistinae treated in his 2011 Monographs of Australian Lepidoptera volume, so I decided to take the time also to update the remainder of this subfamily and to include all post-2019 species I could find. This is now completed, and GLI now includes 1284 names for the group. This total comprises names in Kaila 2019, those from newer papers, fossil names from LepIndex and a few nomina dubia that were not in the catalogue but seem plausibly to refer to elachistine moths. I was not rigorous about adding every historical combination for epithets that have passed through multiple genera, but original combinations and current combinations should all be present, as should original combinations for all synonyms. I did not update the micro-references that were already in place for older names, but the newer names link to structured citations.

Totals are now as follows:

• Subfamily – 1 accepted
• Genus – 14 accepted, 50 synonyms
• Species – 819 accepted, 392 synonyms
• Infraspecific taxa – 1 accepted, 7 synonyms

About five genera and around a dozen other species that were under Elachistidae in LepIndex previously have been moved to other families in the Lepidoptera. Many of these cases are discussed by Kaila, although a few represent highly outdated placements in the NHM catalogue that were apparently not even considered worth discussing. Many small genera have been synonymised into Elachista, Perittia or Stephensia. Four fossil genera are not treated by Kaila but are retained from LepIndex.

I fixed multiple misspellings that occurred in LepIndex either because information on the index cards was incorrect or during transcription into digital format. Despite the scale of the publication, I found no obvious misspellings in Kaila 2019.

Results

Based on these raw numbers, it is clear that LepIndex lacked around 50% of the currently expected number of accepted species for the family and that many synonyms were also missing. The actual situation was even more serious than this appears, because many names were accepted by LepIndex are now considered synonyms, and vice versa.

Here is a summary of results from the largest genus, Elachista. LepIndex had 355 names associated with 327 accepted species in this genus, whereas GLI has 1,046 names for 716 accepted species.

Just 183 (56% of 327) accepted names in LepIndex exactly matched the spelling, authorship and status, and only 9 (32% of 28) synonyms exactly matched the spelling, authorship, status and accepted name offered by GLI. If variation in authorship (mostly missing years and/or parentheses) is ignored, these totals rise to 200 accepted names and 12 synonyms that match the expected species.

81 (25%) of the names accepted for Elachista species by LepIndex are now considered synonyms for other species in the genus. 36 accepted names (11%) now refer to species outside this genus.

6 (21%) of the LepIndex synonyms in this genus are now treated as synonyms for different species

In other words, of the 365 names that LepIndex associated with species in the genus Elachista, even ignoring issues with authorship strings, just 212 (58%) directed users to the currently accepted name for a species.

Reviewing this not from the perspective of what the taxonomic community knows and what names are actually in circulation for species in the genus Elachista (again ignoring issues with authorship):

• Nearly 70% (507 of 716) of the currently accepted species names in Elachista were unknown to LepIndex/COL/GBIF a year ago
• 78% (815 of 1,045) of the names now in TaxonWorks for Elachista species were unknown or incorrectly handled a year ago

Discussion

Elachistinae forms perhaps 0.3-0.4% of the total described Lepidoptera fauna, so these corrections are only a small step towards delivering a comprehensive and reliable catalogue for world Lepidoptera. This subfamily now joins Nepticuloidea, Gracillariidae, Gelechiidae, Lecithoceridae, Alucitidae, Pterophoridae, and Tortricidae as groups that are in good condition in the COL Checklist. Preparations are well under way to bring in some other major family-rank datasets that have been prepared over many years by dedicated groups of taxonomists. Both Geometridae and Bombycoidea are likely to be replaced in the next few months.

The rest of the Lepidoptera is covered by aging datasets. The Global Butterfly Information System dataset (GloBIS/GART) may soon be updated. This covers the Pieridae and Papilionidae. I am working on a refresh for Gaden S. Robinson’s Tineidae dataset which was last updated in 2011. Even the Nepticuloidea (last updated in 2016) is urgently awaiting a planned update. All the rest comes from LepIndex.

The following table compares accepted species counts for the same taxa in different datasets. This is a crude metric – if large numbers of names that should be treated as synonyms are included as accepted species names, this may inflate numbers. However, these numbers show clearly that effort to clean up LepIndex data always leads to significant increases in record counts.

The table shows two calculated estimates for the current total number of described Lepidoptera species. I consider it highly likely that most remaining groups will expand at least 41% as gaps in LepIndex are addressed. Given the large amount of ongoing revisionary work in the Noctuoidea (42,941 species in GLI today), it seems reasonable that this popular group may have gaps as significant as those shown here for Bombycoidea, which would inflate the numbers much further. At a minimum, Catalogue of Life today is likely to be missing 40,000 described Lepidoptera species.

I would note too that many I found for Elachistinae that LepIndex lacked many 19th century European and British names. Some of these are significant omissions, for example names from Haworth, Hübner and Herrich-Schäffer, including the currently accepted name for the widespread species Elachista freyerella (Hübner, 1825) (with hundreds of records in GBIF). Although the NHM card index was maintained into the 1990s, modern publications begin to disappear even from early in the 1980s.

I feel even more than before the need to make the scale of the challenge much more public and for COL to become more proactive in finding and promoting new ways for content to be edited. A traffic-light system for coverage and quality for each taxon would be a big step forward.

Overview

Comprehensive species lists are important tools for taxonomists, field biologists, conservationists, biosecurity officers, policymakers, biodiversity data platforms, amateur naturalists and many others (see the list of open-access papers Towards a global list of accepted species).

Lepidoptera (moths and butterflies) are a hyperdiverse group for which we still lack a high-quality synonymised checklist. Many users and websites rely on LepIndex, a database created from a card index at the Natural History Museum (NHM), London but this is very incomplete and needs significant curation.

The Catalogue of Life (COL) Checklist has treated LepIndex as its primary resource for Lepidoptera but replaces several families with more complete and current datasets from various sources. I have helped to prepare and continue to maintain such datasets for Gelechiidae, Pterophoridae and Alucitidae.

Over the last few years, a copy of LepIndex has been imported into the TaxonWorks online taxonomic workbench tool as the Global Lepidoptera Index, and significant improvements have been made to some sections (especially Bombycoidea and Geometridae). From June 2022, this TaxonWorks dataset replaces the NHM version of LepIndex in COL. TaxonWorks is a collaborative data management tool which opens the door for a much wider community of taxonomists and other experts to work together on delivering a truly comprehensive and current listing of the world’s butterflies and moths.

The challenge

Lepidoptera (moths and butterflies) form one of the largest insect orders. Close to 10% of all known species of living organisms are Lepidoptera. They are among the most easily surveyed and monitored insect groups, with more than 75 million occurrence records in the Global Biodiversity Information Facility (GBIF) today (compared with 22 million records for Coleoptera). As a highly diversified group feeding on most plant species and other substrates, sampling and monitoring Lepidoptera can give broad insights into ecosystem complexity, health and dynamics.

In 2008, John Heppner (p. 627 in: Capinera, J.L. Encyclopedia of Entomology) estimated that the Lepidoptera number 255,000 extant species with around 156,100 currently named. Michael Pogue (Biodiversity of Lepidoptera, pp. 325-355 in Foottit, R.G & Adler P.H. (2009) Insect Biodiversity – Science and Society) offered a calculation (based on multiple datasets) showing 155,181 described species. The Catalogue of Life (COL) Annual Checklist 2021 contained 148,897 accepted Lepidoptera species. Changes discussed here have raised this count to 154,344 accepted species.

During the last few years, I have updated and digitised species lists developed by Klaus Sattler at the Natural History Museum, London for the Gelechiidae and by Cees Gielis at Naturalis, Leiden for the Alucitidae (including Tineodidae), Pterophoridae and Macropiratidae. This affords an opportunity to assess the completeness of LepIndex and the accuracy of the estimates in Capinera 2008 and Pogue 2009. The following table compares the counts of accepted species in each of these groups in Pogue 2009 and the current datasets now in Catalogue of Life:

In each of these groups, at least 25% more species have been described and are currently accepted by taxonomists than are indicated in the published estimates. It therefore seems likely that the total count of currently described Lepidoptera species may be much closer to 200,000.

However, partly owing to the continued level of taxonomic research across the group and partly because of the sheer size of the order, there is still no truly comprehensive and current list of described species for this group. For many years, the Global Lepidoptera Names Index (LepIndex) has served as the reference checklist used by many biodiversity data platforms to organise data on Lepidoptera. LepIndex is a digitised and updated version of an index card archive to the scientific names of the living and fossil butterflies and moths of the world produced over many decades by lepidopterists at the Natural History Museum (London). The stated coverage for this dataset is 137,441 species.

The current situation

For many years, LepIndex has provided most of the Lepidoptera names and classification used in the Catalogue of Life (COL) Checklist, although several families have been sourced from other datasets that have been more fully curated by taxonomists familiar with the groups, specifically:

• Alucitidae (including the former Tineodidae) from Catalogue of the Alucitoidea of the World
• Gracillariidae from Global Gracillariidae: Global Taxonomic Database of Gracillariidae
• Lycaenidae, Pieridae and Papilionidae from the Global Butterfly Information System (GloBIS)
• Nepticulidae and Opostegidae from Nepticulidae and Opostegidae of the World
• Pterophoridae and Macropiratidae from Catalogue of the Pterophoroidea of the World
• Tineidae from Global taxonomic database of Tineidae (Lepidoptera)

The remainder of the Lepidoptera coverage (120 families) in COL comes from LepIndex.

The NHM card index was a nomenclatural catalogue rather than a synonymic species list and was never completely curated to reflect all revisions of the order. Coverage of literature from the 1980s onwards is very incomplete and the last edits to the dataset were made in 2018. As a result, LepIndex has the following weaknesses as a resource for organising biodiversity data:

• Large numbers of new names, combinations and revisions are missing, especially from the last 30 years.
• The original generic placement (original combination) for many names is not reliably recorded – this at least makes LepIndex unreliable for determining whether parentheses are required around authorship.
• The only combinations that may be provided are the original combination and one current when each card was last edited – in many cases, only one combination is available.
• Many names currently considered synonyms are shown as (provisionally) accepted.
• For the most part, higher classification is limited to family and these do not map consistently to current family concepts, especially in superfamilies such as Gelechioidea and Noctuoidea.
• A significant number of names were mistranscribed from the original card images resulting in inaccurate spellings.

Despite these flaws, LepIndex has remained in use as a reference classification because no other digital resource is as comprehensive. Even Markku Savela’s excellent Lepidoptera and some other life forms site (which accurately handles much of the more recent literature) contains slightly under 117,000 species and Wikispecies contains under 112,500 pages that include the word “Lepidoptera” (including many that relate to other ranks than species, literature references including the word, etc.). As platforms such as GBIF have expanded their importance, the weaknesses of LepIndex have become clearer and more pressing.

The response

LepIndex has been migrated into the TaxonWorks online taxonomic workbench platform developed and maintained by the Species File Group in Illinois. This is a rich editing environment for nomenclatural and taxonomic datasets and provides many useful tools for editors to contribute updates and corrections.

Many corrections and updates have been applied to the TaxonWorks version of LepIndex, including major revisions to the Bombycoidea and some other families.

The dataset will regularly be published to ChecklistBank as the Global Lepidoptera Index. ChecklistBank is an online platform developed by GBIF and COL to hosts checklist datasets and including the tools used each month to construct the COL Checklist. ChecklistBank also allows any dataset to be downloaded in multiple formats or accessed through a public API.

Additionally, a new family dataset for the Gelechiidae (Catalogue of World Gelechiidae) is now available in ChecklistBank. This is based on the list maintained over many years by Klaus Sattler at NHM but has been updated to include changes made in the literature in the last five years and to serve as a placeholder for a few names that were included as Gelechiidae in LepIndex but that have no current accepted family placement. Associated changes have also been made to the Global Lepidoptera Index to move other species that were previously considered to be Gelechiidae into the currently accepted family.

Now that these datasets are accessible through ChecklistBank, the June 2022 edition of Catalogue of Life includes them in its construction. The following table summarises the current components of the COL Checklist for Lepidoptera.

I plan to integrate the Gelechiidae, Pterophoridae/Macropiratidae and Alucitidae datasets into the Global Lepidoptera Index dataset. The Nepticulidae/Opostegidae, Gracillariidae and Papilionidae/Pieridae datasets are actively maintained outside TaxonWorks but more regular imports are needed. The Tineidae need more work but are also likely to be merged into the Global Lepidoptera Index.

How to contribute

More work is required on almost all other families. Discussions are underway to bring in copies of well-managed datasets for several other families, but contributors or editors are sought for other components. Contributions may take any of the following forms:

1. Regular copies of existing global superfamily/family/subfamily/tribe datasets that are already maintained externally using other tools. Merging efforts around TaxonWorks as a common platform for all lepidopteran groups would bring significant benefits, but the priority is to maintain high-quality checklists for each group.
2. A single copy of an existing global superfamily/family/subfamily/tribe that can be shared with COL under a Creative Commons Attribution (CC BY) or Creative Commons Zero (CC0) licence.
3. Editors (or teams of editors) ready to assume responsibility for updating and maintaining a group within the Global Lepidoptera Index. We can arrange training in the use of the tools.

In all cases, COL advocates for the approach outlined in Garnett et al. 2020 Principles for creating a single authoritative list of the world’s species. Lists should be developed collaboratively by taxonomists and other experts working on the group. Decision processes should be transparent and aim to secure an appropriate consensus view. As far as possible, there should be no barriers to contribution and participation by relevant taxonomists from any region.

Since an increasing proportion of new and even historical taxonomic literature is being made accessible in structured formats (e.g. Pensoft journals, Plazi TreatmentBank), and since most of these datasets will be accessible through ChecklistBank, there is a great opportunity to automate (or semi-automate) inclusion of new taxa, combinations and synonymy.