Introduction

Hedwig (1801)'s publication Species muscorum frondosorum is the designated starting point for the nomenclature of mosses, excluding the Sphagnaceae (Turland et al., 2018: Art. 13.1(b)). The majority of the mosses that were newly described or validated in Hedwig's work represent well-known, mostly widespread species from the northern hemisphere, although some species also originated from the tropics or southern hemisphere. The latter were mainly based on collections made by the Swedish botanist Olof Peter Swartz (1760–1818), in the most part from Jamaica, or by the Swedish naturalist Carl Peter Thunberg (1743–1828) from South Africa.

The retrospective typification of moss names that were validated in Hedwig (1801) but were based on names that originated from works published before 1 January 1801 can be complicated (see Geissler, 2000; Price, 2005). For these names, the history of each of the entities cited in the protologue often needs to be disentangled in order to identify the original material related to the name, to establish the historical concepts related to the entities themselves, as well as to determine the origin(s) of the material on the Hedwig herbarium sheets (see Ellis & Price, 2013, 2015). The situation concerning the treatment of species and varieties that were described as new to science by Hedwig (see Price & Ellis, 2011) is usually more straightforward as the single specimens in the Hedwig collection, that agree with the protologue, represent holotypes (even though type designation was not widely practiced by authors at that time, see Turland et al., 2018: Art. 9.1) and further typification only needs to be carried out in cases where more than one sheet is present per name, where later specimens of different origins have been added to the sheet and/or where two, or more, different taxa are present on a sheet (e.g. Weissia calycina Hedw., Price, 2002), or when the specimens have not been located (see Appendix I). In addition, the over two-hundred year old specimen(s) must be carefully examined in situ to confirm the identity of the specimens, and thus to ensure the taxonomic identity of the material and the correct application of the name in question.

During a recent move of the cryptogamic collections in G for renovation work, seven folders from the Hedwig- Schwägrichen herbarium were found in one of the original Hedwig herbarium storage cases (see Price, 2005: Fig. 2). Four of these folders, labelled in Hedwig's handwriting “Grimmia”, “Orthotrichum”, “Phascum” and “Weissia”, each contained a single herbarium sheet. These were either unlabelled or labelled by C.F. Schwägrichen, and held packets of different species (between 3 and 19 sub-packets per sheet). They presumably constituted a reference collection for each of these genera. All the sub-packets on these sheets are labelled in the handwriting of Schwägrichen. A single folder, labelled “Neckera” by Hedwig, was empty, while the remaining two folders were labelled by Schwägrichen, one as “Racomitrium” and the other as “Notarisia Hamp”. The first contained a single herbarium sheet with three subpackets of Racomitrium specimens attached, and the second contained two loose subpackets and three herbarium sheets of “Encalypta crispata”. Two of the herbarium sheets lacked label information and, respectively, had one and two specimens that were glued directly to the sheet. The final sheet was identified as the missing type of Hedwig's Encalypta crispata Hedw. (≡ Ptychomitrium crispatum (Hedw.) A. Jaeger).

The herbarium sheet for Encalypta crispata [G00048628] (Fig. 1) could be easily identified as original to Hedwig based on the combination of the characteristic blue specimen cover, the distinctive paper and format of the herbarium sheet, the specimen label in Hedwig's handwriting, and the typical arrangement of the plants on the sheet (see images in Price, 2005). The locality information given on the herbarium sheet label corresponds to that in the protologue, and the plant on the left side of the sheet [G00048628] (Fig. 1) also resembles the original illustration in Hedwig (1801: tab. 10 and Fig. 2). Based on the observation of plant material from numerous Hedwig herbarium sheets by the present author it appears that a number of his specimens were wetted and then pressed in the wet state, before being glued to the herbarium sheets, either as single specimens or in one or several rows of single or multiple plants. The material of Encalypta crispatum contains one plant that was treated in this way and one that was attached when it was dry. After careful examination of the two stems in situ using a dissecting microscope, and via the careful removal of one leaf from each of the plants for microscopic determination both stems on the herbarium sheet “Encalypta crispata” were confirmed as being Encalypta crispata. After examination the material was placed into labelled sub-packets and returned to the specimen.

Hedwig's “Encalypta crispata” has an uncomplicated nomenclatural history. Between 1819 and 1849 this species was transferred (see typification section below) to the Grimmiaceae (under Grimmia Hedw.), Ptychomitriaceae (under Brachysteleum Rchb., Brachypodium Brid. [nom. illeg.], and Notarisia Hampe, all now synonyms of Ptychomitrium Fürnr.) or Orthotrichaceae (under Orthotrichum Hedw.) before being recognised as belonging to Ptychomitrium by Jaeger (1874: part 4) where it has remained ever since.

A type for Hedwig's Encalypta crispate

Encalypta crispata was newly described by Hedwig (1801) based on plants collected by the Swedish naturalist C.P. Thunberg from the Cape of Good Hope, South Africa. Hedwig (1801) gave the following diagnosis for his new species “Encalypta crispata divisa, foliis lineari-lanceolatus acuminatus madore patentibus siccitate tortilibus, sporangiis crebis cylindricis.”, evoking its linear-lanceolate, acuminate leaves that are spreading when moist and twisted when dry, and its numerous cylindrical capsules. He also provided an illustration (Hedwig, 1801: tab. 10, fig. 1–9) and succinct description of it: “Truncus aetate crebro divisus, erectus. Folia conferta, bene madida patentia reflexaque, siccitate crispata, ductulorum fasciculo lutescente. Pedunculi breves, pallidi. Sporangia cylindrica, viridantia matura, atque evacuata e luteo fuscidula. Operculum recta rostratratum, rubrum. Annulus tenuis.” [The trunk (stem) is often branched with age, erect. Leaves crowded, spreading and recurved when wet, crisped when dry, nerve deep yellow. Seta short, pale. Capsules cylindrical, green when mature, dark yellow when empty. Operculum straight, beaked, red. Annulus thin.]

Fig. 1.

- The rediscovered holotype of Hedwig's Encalypta crispata Hedw at G.

Fig. 2.

- Original illustration of Encalypta crispata Hedw. from Hedwig's Species muscorum frondosorum of 1801, tab. 10. [Original figure legend: “fig. 1. planta naturali magnitudine, fig 2. eadem acuta lente o., fig. 3. folium augm. III., fig. 4. sporangium operculatum augm. I. fig. 5. sporangii pars augm. III. fig. 6. peristomii dens augm. IV. fig. 7. Flos masculus augm. III. fig. 8. folliculi augm. IV. fig 9. filum succulentum floris augm. IV.”]

Fig. 3.-

Ptychomitrium crispatum (Hedw.) A. Jaeger. A. Plants in dry (left) and wet (right) state; B. Leaves; C. Leaf cross-sections from leaf base, middle, upper part and apex (left to right); D. Basal cells; E. Cells from widest part of the leaf; F. Upper leaf cells; G. Leaf apex; H. Operculum; I. Calyptra; J. Peristome teeth (outer side). [A–D, F: Hedderson 15676 (BOL); E, G–J: Wilms s.n. (G)]