17.3.2. Unofficial taxonomies
As explained elsewhere in this book, the sheer diversity of the insects means that even some fairly commonly encountered species are not described formally yet. Only in Britain can it really be said that the total fauna is described and recognizable using identification keys. Elsewhere, the undescribed and unidentifiable proportion of the fauna can be substantial. This is an impediment to understanding how to separate species and communicate information about them. In response to the lack of formal names and keys, some “informal” taxonomies have arisen, which bypass the time- consuming formal distinguishing and naming of species. Although these taxonomies are not intended to be permanent, they do fulfill a need and can be effective. One practical system is the use of voucher numbers or codes as unique identifiers of species or morphospecies, following comparative morphological analysis across the complete geographical range of the taxa but prior to the formal act of publishing names as Latin binomens (section 1.4). If the informal name is in the form of a species name, these are referred to as manuscript names — and sometimes they never do become published. However, in this system, taxa can be compared across their distributional and ecological range in identical manner to taxa provided with formal names.
In narrower treatments, informal codes refer only to the biota of a limited region, typically in association with an inventory (survey) of a restricted area. The codes allocated in these studies typically represent morphospecies (estimates of species based on morphological criteria), which may not have been compared with specimens from other areas. Furthermore, the informal coded units may include taxa that may have been described formally from elsewhere. This system suffers lack of comparability of units with those from other areas — it is impossible to assess beta diversity (species turnover with distance). Furthermore, vouchers (morphospecies) may or may not correspond to real biological units — although strictly this criticism applies to a greater or lesser extent to all forms of taxonomic arrangements. For simple number-counting exercises at sites, with no further questions being asked of the data, a morphospecies voucher system can approximate reality, unless confused by, for example, polymorphism, cryptic species, or unassociated life-history stages.
Essential to all informal taxonomies is the need to retain voucher specimens for each segregate. This allows contemporary and future researchers to integrate informal taxa into the standardized system, and retain the association of biological information with the names, be they formal or informal. In many cases where informality is advocated, ignorance of the taxonomic process is at the heart — but in others, the sheer numbers of readily segregated morphospecies that lack formal identification requires such an approach.