Hedwigidium

Description. Plants medium or robust (2- 3 cm), in loose or dense, tufts or mats, dark green or red-brown. Stems sympodially branched, plagiotropic, tips ascending; branches short, terete and blunt, some stoloniform. Pseudoparaphyllia foliose, base much wider than long, lobed-dentate, cells papillose.

Leaves imbricate, spreading, concave, weakly plicate, short ovate, ovate lanceolate to narrow lanceolate, apiculate, or gradually acuminate; ecostate; apex concolorous, entire, erose, crenulate or serrulate; margins revolute or narrowly recurved up to the base of the acumen; leaf cells thick-walled, sinuose, medial and upper cells with 3-4 low, rounded, unbranched papillae, marginal, bending over lumen; apical cells, short to long elliptical; upper cells long-rectangular to subquadrate or oblate; basal median cells long-rectangular, yellow; basal marginal cells shorty rectangular, quadrate, or oblate, smooth, dark reddish brown.

Autoicous. Perigonia terminal on short sympodia, alternating with sympodia terminated with perichaetia. Perichaetial leaves erect, elongate, overtopping the capsules, margins entire, undulate; paraphyses short, or as long as the perichaetial leaves.

Setae short; neck very short ampullaceus; capsules immersed, erect, symmetric, broadly urceolate, subglobose, to cyathiform; furrowed when wet or dry, red brown; macrostomus; exothecial cells subquadrate, isodiametric to oblong; stomata few, superficial, only at neck; operculum base conic, umbonate, rounded or small rostellate.

Calyptra cucullate, small, or conic mitrate, 1.5 mm long, 2–4-lobed, covering only the operculum.

Spores 20 (24–27) -33 μm, vermiculate-papillose.

Hedwigidium imberbe, on rock; near Villareal, Tlaxcala. México.

Species: 1.

Distribution

Europe: United Kingdom, Norway, France, Italy, and Spain. Africa: Cameroon, DR Congo, Malawi, Tanzania, Uganda, Zimbabwe, Reunion Island, Kenya. South Africa.

Asia: India, Sri Lanka, Indonesia. Australia, New Zealand. Central America: Mexico, Guatemala, El Salvador, Honduras, Costa Rica, Dominican Republic.

South America: Venezuela, Colombia, Ecuador, Perú, Bolivia, Chile, Argentina, Brazil.

Hedwigidium imberbe (Sm.) Bruch & Schimp. Bryol. Eur. 3
(fasc. 29-30): 157. 1846.

≡ Gymnostomum imberbe Sm., Engl. Bot. 32: 2237. 1811

≡ Anictangium imberbe (Sm.) Hook. & Taylor, Muscol. Brit. 14. 1818

≡ Schistidium imberbe (Sm.) Nees & Hornsch., Bryol. Germ. 1: 99. 1823

≡ Anictangium ciliatum var. rufescens Arnott, Mém. Soc. Linn. Paris 5: 226. 1827

≡ Schistidium ciliatum var. imberbe (Sm.) Huebener, Muscologia Germanica 30. 1833

≡ Hedwigia imberbis (Sm.) Spruce, Musci Pyren. 263. 1847

≡ Neckera imberbis (Sm.) Müll. Hal., Syn. Musc. Frond. 2: 105. 1851

≡ Braunia imberbis (Sm.) N. Dalton & D.G. Long, J. Bryol. 34(1): 60. 2012.

Type citation: “Discovered on dry rocks upon mountains in the west of Ireland by Miss Hutchins, who in 1809 sent specimens to Mr. Turner, which he has kindly communicated to us”.

TYPE: UNITED KINGDOM. Ireland, Glengariff, 1810, Miss (Ellen) Hutchins. Mr. Turner s.n. (holotype: LINN, isotype: BM).

Since Bruch and Schimper (1846) established Hedwigidium, a few more species have been classified in the genus.

Jaeger (1876), besides H. imberbe, listed H. emersum (Müll. Hal. & Hampe) A. Jaeger from New Zealand, and H. drummondi (Taylor) A. Jaeger from western Australia; a few years later he added H. rhabdocarpum (Hampe) A. Jaeger from Colombia and H. glyphocarpum (Hampe) A. Jaeger from Brasil (Jaeger 1880).

Two more species were included in the genus when Paris (1896) first listed H. teres (Müll. Hal.) Paris from central Africa (Mount Kilimanjaro); from South Africa he added H. erosum (Müll. Hal.) Paris.

The last two species to be included in the genus were H. macrocalyx (Müll. Hal.) Paris and H. serrae (Müll. Hal.) Paris, both from southwestern Brasil (Paris, 1900). Ultimately all these species have been traditionally considered synonyms under H. imberbe.

Taxonomic work in progress evaluating type specimens and worldwide morphological variation might reveal several species. Meanwhile the genus is here considered monotypic (De Luna, 2021).

Hedwigidium imberbe, on rock; near Cofre de Perote, Veracruz. México.

Fig. 4. Morphological features of Hedwigidium Bruch & Schimp. A-B. leaves; C-D. perichaetial leaves; E. sporophyte (A-E, from Sharp 5449 (DUKE), Guatemala); F-G. leaves; H. perichaetial leaf (F-H, from Adams s.n. (BM), Cameroon). [from De Luna 2021]

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Pictures of habitat and morphological features of Hedwigidium imberbe from Great Britain and Ireland (as Braunia imberbis)

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As exposed by Allen (2010), the correct identity and nomenclature for the only species in the genus must be Hedwigidium imberbe (Sm.) Bruch & Schimp.

Allen (2010) aptly discovered that the well-known name Hedwigidium integrifolium (P. Beauv.) Dixon was widely misapplied in the literature and herbarium specimens.

Later, Dalton et al. (2012) also acknowledged that Hedwigia integrifolia differs from Hedwigidium imberbe in several important characters, supporting their taxonomic separation from Hedwigia P. Beauv. They examined the type for Hedwigia integrifolia and corroborated that it belongs in Hedwigia.

Dalton et al. (2012) moved Hedwigidium imberbe (Fig. 1) to Braunia Bruch & Schimp. Dalton et al. (2012) made the new combination Braunia imberbis (Sm.) N. Dalton & D.G. Long, consequently synonymizing Hedwigidium with Braunia.

As justification for this hypothesis, Dalton et al. (2012) asserted “… some Braunia species have a seta as short as that of Hedwigidium – in B. reflexifolia (Müll. Hal.) E.B. Bartram seta length is 2 mm or less.” They argued: “Seta length cannot therefore be used as a clear-cut generic character.”

However, the proposition that Dalton et al. (2012) presented for the generic classification and for the name of this species, as Braunia imberbis, was unsupported and flawed. Their taxonomic inferences were undermined, because they did not report data and formal analysis of seta length to test the generic status of this species in Hedwigidium or as a species in Braunia. When assessing Hedwigidium and Braunia, they disregarded differences in seta length.

The data and results of analyses of seta lenth variation presented by De Luna (2021) refute and overturn the proposed synonymy of Hedwigidium and Braunia in favor of conserving the original hypothesis of Hedwigidium as a separate genus.

References:

Fife, A.J. 2014. Hedwigiaceae. In: Heenan, P.B.; Breitwieser, I.; Wilton, A.D. Flora of New Zealand -Mosses. Fascicle 14. Manaaki Whenua Press, Lincoln.
http://dx.doi.org/10.7931/J2X63JTQ

Gilmore SR. 2012. Australian Mosses Online. 4. Hedwigiaceae.
http://www.anbg.gov.au/abrs/Mosses_online/Hedwigiaceae.pdf

Brotherus, V. F. 1909. Hedwigiaceae. In: A. Engler & K. Prantl, eds. Die natürlichen Pflanzenfamilien 1(3): 712–722. W. Engelman, Leipzig.

Bruch, P., Schimper, W. P. & Gümbel, W. v. T. 1846. Bryologia Europaea, seu Genera Muscorum Europaeorum monographice illustrata. Vol. III. E. Schweizerbart, Stuttgart.

Dalton, N.J.; Kungu, E.M.; Long, D.G. 2012: The misapplication of Hedwigia integrifolia P.Beauv. and identity of Gymnostomum imberbe Sm. (Hedwigiaceae, Bryopsida). Journal of Bryology 34: 59–61.

Dalton, N.J., Kungu, E. M. & Long, D. G. 2013. A taxonomic revision of Hedwigiaceae Schimp. from the Sino-Himalaya. Journal of Bryology, 35: 96–111.

De Luna E. 1992. Developmental and systematic studies in the Hedwigiaceae (Musci). PhD thesis. Duke University, Durham, NC.

De Luna, E. 2021. Seta length variation and the refutation of Hedwigidium = Braunia (Hedwigiaceae, Bryopsida). Acta Botanica Mexicana 128: e1810.

Jaeger A. 1876. Genera et species muscorum systematice disposita seu Adumbratio florae muscorum totius orbis terrarum. VI, p 85-188.

Sharp, A. J., Gardner, R. & Giesy, R. M. 1978. SEM separation of sterile specimens of Hedwigidium integrifolium, Braunia secunda and B. squarrulosa. Phytomorphology, 28: 329-331.

Hedwigidium imberbe, on rock; Spain (listed as Braunia imberbis)

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Hedwigidium imberbe from France (as Braunia imberbis)

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Figure of Hedwigidium imberbe from Australia (Gilmore 2012)

FROM THE ONLINE VERSION OF CENTRAL AMERICAN MOSSES

Hedwigidium is a monospecific genus found throughout the Southern Hemisphere as well as Europe and Mexico. The sporophytes of Hedwigidium and Hedwigia are immersed, and the genera are sometimes (Nyholm 1960; Scott & Stone 1976; Smith 1978; Casas 1991; Hedenäs 1998; Cortini Pedrotii 2001) considered synonymous.

The gametophytes of Hedwigidium differ from those of Hedwigia in having stoloniferous stems and branches and leaves with concolorous or narrowly hairpointed apices. In contrast the stems and branches of Hedwigia rarely produce stolons, and its leaves have very broad, hair-pointed apices.

Braunia differs from Hedwigidium in having long-exserted capsules, but their gametophytic characters matched so closely that the two genera are sometimes difficult to distinguish from one another. Pseudobraunia is found nearby in California and, like Braunia, it too has long-exserted capsules. Pseudobraunia further differs from Hedwigidium in having leaves with consistently long, hyaline hair-points and single, long, stout leaf cell papillae.

Hedwigidium imberbe is fairly common in Central America on rocks at high elevations. It has
erect-imbricate leaves with usually concolorous apices, but the branch leaves can sometimes be hyalinetipped and the stolon leaves are often long hair-pointed. Other critical gametophytic features of the species include its strongly recurved leaf margins, long, sinuose upper leaf cells, low leaf cell papillae
scattered over the cell lumina, and exceptionally well-differentiated, commonly dark red cells in
the alar regions. The species is autoicous, with gemmate perigonia occurring close to the perichaetia,
and collections often have sporophytes. The sporophytes are not always evident because they are
deeply immersed, but they can be found because the perichaetial leaves are greatly enlarged.

Although Hedwigidium imberbe and Hedwigia nivalis are similar in having immersed capsules,
their gametophytes are distinctly different. The leaves of Hedwigidium imberbe have concolorous or
narrowly hair-pointed apices with multiple, low papillae scattered over the leaf cells, and its perichaetial
leaves are entire. In Hedwigia nivalis the leaves have very broad hair-pointed apices, and
high, stout leaf cell papillae, and the perichaetial leaves are ciliate.
Braunia differs from Hedwigidium imberbe in having long-exserted capsules, but collections that
lack sporophytes can be difficult to place to genus. In Central America B. andrieuxii differs from
H. imberbe in having leaf margins recurved only in the lower half or less and shorter, straight-walled
upper leaf cells, while B. squarrulosa differs in having leaves with long hyaline hair-points that are
strongly reflexed when dry. The leaves of Braunia secunda are quite similar to those of H. imberbe
in stance, shape, apex form, and in having strongly recurved leaf margins. The basal leaf cells of
H. imberbe, however, are strongly red colored in the alar regions and relatively short in the median
regions. In contrast, the basal cells of B. secunda are yellowish in the alar regions and relatively long
in the median regions, but these basal leaf cell distinctions can be difficult to make without previous
experience with the species.
Hedwigidium imberbe has generally been associated with the older Hedwigia integrifolia
P. Beauv. since Hooker and Taylor (1818) first synonymized the two species (as Anictangium imberbe).
Jones (1933), however, considered Hedwigia integrifolia a synonym of Hedwigia ciliata.
Hedwigia integrifolia clearly is not a synonym of Hedwigidium imberbe for two reasons: its type
came from North America and it is described as having ciliate perichaetial leaves. Hedwigidium imberbe
does not occur in North America and its perichaetial leaves are entire. It seems likely Jones
(1933) was correct in treating Hedwigia integrifolia as a synonym of Hedwigia ciliata. Not only do
both taxa have ciliate perichaetial leaves, but Palisot de Beauvois (1805) considered H. integrifolia
very close to or a variety of Hedwigia filiformis (Mich.) P. Beauv. Michaux (1803) considered H. filiformis
to differ from H. ciliata only in being a smaller, more slender plant with non-scarious leaf
apices.

Image of Hedwigidium imberbe; from Pictures from the CD Neotropis 1 - plate 1. M. Lüth

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Image of Hedwigidium glyphocarpum at (P)

From

Fife, A.J. 2014: Hedwigiaceae. In: Heenan, P.B.; Breitwieser, I.; Wilton, A.D. Flora of New Zealand - Mosses. Fascicle 14. Manaaki Whenua Press, Lincoln.

The genus is considered here to be monotypic.
The separation of Hedwigidium from Hedwigia is supported by the morphological studies of de Luna (1995); his concepts are followed here. Brotherus (1925, p. 70) considered Hedwigidium to contain two species, but Magill & van Rooy (1998) placed the South African H. erosum (Müll.Hal.) Paris into synonymy.

The status and typification of the genus Hedwigidium was discussed by Dalton et al. (2012). They considered Hedwigidium to be typified by the Irish H. imberbe (Sm.) Bruch & Schimp. and suggested that Hedwigidium be placed in synonymy with Braunia. If their synonymy is accepted, the nomenclatural implications for N.Z. material (which clearly does not belong to Hedwigia, as they
suggest) are complicated and unclear. These problems are beyond the scope of this Flora, and are best resolved in a monographic context.

See description and excellent illustrations in Fife (2014).

Figure of Hedwigidium imberbe, from Fife 2014


Contents of this website Introduction Phylogenetic classification Hedwigiaceae Taxonomic treatment Keys to genera Braunia Hedwigia Hedwigidium Pseudobraunia (link to Flora of North America) Bibliography

HEDWIGIDIUM Bruch & Schimper, Bryol. Eur. 3: 155 (1846). Type: Hedwigidium imberbe (Sm.) Bruch & Schimp. Hedwigia sect. Hedwigidium (Bruch & Schimp.) Mitt. J. Proc. Linn. Soc., Bot. 7: 160. 1863. Harrisonia subg. Hedwigidium (Bruch & Schimp.) Hampe. Verh. Zool.-Bot. Ges. Wien 21: 386. 1871. Hedwigia subg. Hedwigidium (Bruch & Schimp.) Lindb. Musci Scand. 40. 1879. Braunia sect. Hedwigidium (Bruch & Schimp.) Müll. Hal. Linnaea 42: 378. 1879. Not: Hedwigidium integrifolium (P.Beauv.) C.E.O.Jensen, Skand. Bladmossfl., 369. 1939. (= Hedwigia integrifolia P.Beauv., Prodr. Aethéogam, 60. 1805).