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Moss Type Specimens at the Natural History Museum

Project funded by GBIF

The moss collections

moss - close up of specimenThe Cryptogamic Herbarium at the Natural History Museum, London (BM) contains about 780,000 specimens of mosses, of which about 20,000 are types. These represent types of between 4,000 and 7,000 scientific names, with an average of 3 to 5 isotypes or syntypes for each name, where they can be studied. Historically, these have been kept in folders in herbarium cabinets, arranged according to our concepts of their relationships.

Modern systematic practice requires that a single specimen be acknowledged as the type of the species (holotype or lectotype). However, during the early period of scientific study of mosses, experts would often cite several specimens as examples of their new species, but rarely designated individual specimens as types. Because mosses are often clonal, collectors frequently made several duplicates from individual collections, and sent these to different experts for examination. Consequently, for any single species the description may cite several collections (syntypes), each of which may consist of several duplicates (isotypes), all of which have to be considered as candidates to be the type of the species. Furthermore, different experts often described new species from these collections without knowing what other specialists were doing, so that different species might be described from duplicates of the same specimen. In order to determine how many species really exist it is necessary to unravel this complex situation by examining the type specimens. However, part of this process can be streamlined by inspecting images of putative types, which allows a certain proportion of the specimens to be eliminated from consideration.

Type specimens in the Cryptogamic Herbarium of the Natural History Museum are kept in folders marked with a red border, and interleaved with the general collections kept in plain folders. However, although some groups of mosses have been studied and revised, many have barely been looked at since they were first collected. Consequently, type folders may also contain specimens that are not types, and type specimens may be located in general folders. Currently we do not really know how many type specimens we have, and cannot easily find them when they are needed for study. This represents an enormous amount of information that is not readily available to the world. Faced with the rapid loss of species through destruction of the natural environment, it is imperative that this information be retrieved so that we can use it to help us understand biodiversity and the processes of origin, maintenance and extinction of species.

In addition to data on the species, a lot of other information is associated with these specimens. A total of 283 different collectors and 95 authors of scientific names are represented in the moss herbarium. Many of the collections were described and named by some of the most prolific authors of moss names, including H. N. Dixon (1,524 published names), E. Besherelle (1,414 names), E. Hampe (1,171 names), W. P. Schimper (898 names), W. J. & J. D. Hooker (757 names) and W. Wilson (465 names). These authors published between them 6,229 of the 41,300 legitimate specific and infra-specific recorded on the MOST Tropicos database.