Fissidens celticus

Fissidens celticus, also known by its common name Welsh pocket-moss, is a species of moss in the family Fissidentaceae. It was discovered in 1958 in Pembrokeshire by A.H. Norkett and was first described as a new species by Jean Paton in 1965.^[3]

Fissidens celticus
Conservation status
Least Concern  (IUCN 3.1)[1][2]
Scientific classification
Kingdom:	Plantae
Division:	Bryophyta
Class:	Bryopsida
Subclass:	Dicranidae
Order:	Dicranales
Family:	Fissidentaceae
Genus:	Fissidens
Species:	F. celticus
Binomial name
Fissidens celticus Paton, 1965

Description

Fissidens celticus has shoots up to 4.5 millimetres (0.18 in) tall and 1–1.5 millimetres (0.039–0.059 in) wide.^[4] Each shoot has many leaves, often 10 pairs or more, of equal size.^[4] The nerve in each leaf runs all the way to the leaf tip and has a distinct bend about halfway along the leaf.^[4] Male plants and capsules are not known,^[5] and it is uncertain how the species disperses.^[6]

Fissidens celticus can be distinguished from F. exilis by its longer shoots, its greater number of leaves and its lack of capsules.^[4]

Habitat

Fissidens celticus grows on shaded soil banks near woodland streams, especially on bare, compact patches eroded by floodwater.^[4] It has an altitude range of between 5 and 300 metres (16.4 and 984 feet).^[3]

Distribution

Fissidens celticus is generally believed to be widespread and common within suitable localities. It is apparently endemic to western Europe and there is no evidence of population decline.^[1]

Within the United Kingdom

The species holotype was from Hustyn Wood, St Breock, Cornwall,^[6] and it is common throughout the western parts of the United Kingdom.^[3] In the United Kingdom, F. celticus often associates with Calypogeia arguta,^[3] Diplophyllum albicans,^[3] Dicranella heteromalla,^[6] Dicranella rufescens,^[3][7] Epipterygium tozeri,^[3] F. bryoides,^[3] Pellia epiphylla,^[3] Pohlia lutescens,^[3] and Pseudotaxiphyllum elegans.^[3]

England

Fissidens celticus is most commonly found in South West England, but is also present in the south east and north west.^[3]

There are records of F. celticus from Cornwall,^[6] Devon,^[8] Gloucestershire,^[9] Kent,^[10] and Sussex.^[11] On the Isle of Wight, it is present in Parkhurst Forest,^[12] and at Briddlesford Nature Reserve.^[13] As of 2001, the only known record in Lancashire was on the River Lune Biological Heritage Site.^[14]

Wales

The species can be found all across western Wales,^[3][15] including on Anglesey.^[16]

Scotland

Fissidens celticus is present in much of western Scotland.^[3] The Tayvallich Juniper and Fen SSSI (near Tayvallich, Argyll and Bute) is noted for its oceanic bryophytes, including F. celticus.^[17]

Northern Ireland

In Northern Ireland, the only known location for F. celticus is in Ness Wood ASSI in County Londonderry.^[18]

Elsewhere

Fissidens celticus has been recorded in many other countries in Europe:

• Germany: in the Leuscheid associating with F. bryoides, Dicranella heteromalla, and Diplophyllum albicans.^[19]
• Ireland: one specimen the Slieveardagh Hills, County Tipperary and two in County Cork near Kilworth; associating with F. bryoides and F. taxifolius.^[20]
• Spain: in the Aiako Harriak Natural Park associating with F. viridulus.^[21]
• Switzerland: in the cantons of Bern, St. Gallen, and Ticino.^[5]

In 2019, it was first reported in Turkey (and therefore in Asia).^[22] It was found in Bozyazı, Mersin Province, associating with Bartramia stricta, Bryum dichotomum, Didymodon tophaceus, Targionia hypophylla and Timmiella barbuloides.^[22]