In the present study, by combining molecular and morphological studies, we confirm that T. brachydontium includes at least four clearly distinct taxa. Based on the present work, we consider species rank to be the most suitable option.
5.1. The List of Taxa
An account of the four species within T. brachydontium s.l. accepted in the present work is given below. Information is provided regarding types, nomenclature, taxonomy and etymology, morphological descriptions, diagnostic characters for infra-specific taxa, pertinent observations on morphology and distribution and habitat.
(1)
Trichostomum brachydontium Bruch in F.A. Müll., Flora 12: 393, pl. 3. 1829 (
Figure 3 and
Figure 4). Type citation: “An einer feuchten Erdwand bei Spezzia und auf Hügeln unter Gebüsch bei Cagliari. März und April”. Lectotype (designated here): (Italy, Sardinia)
Trichostomum brachydontium Bruch, In umbrosis ad terram prope Cagliari. Febr. U. I.
Müller, JE 04008873!; Isolectotype:
Trichostomum brachydontium Bruch, In umbrosis ad terram prope Cagliari. Febr. U. I.
Müller, PC 0703925. Syntypes: (Italy, Sardinia)
Trichostomum brachydontium Br, In umbrosis ad terram pr. Cagliari, Febr.
F. Müller, JE 04008874!; (Italy)
Trichostomum mutabile Br. Eur., Golfo di Spezzia, Muller 1828, BM000666185.
Other names for this basionym: Didymodon brachydontius (Bruch in F.A. Müll.) Wilson, Brit. Fl. (ed. 4) 2: 30. 1833 ≡ Tortula brachydontia (Bruch in F.A. Müll.) Mitt., J. Linn. Soc., Bot. 12: 148. 1869 ≡ Mollia brachydontia (Bruch in F.A. Müll.) Lindb., Musci Scand. 21. 1879 ≡ Tortella brachydontia (Bruch in F.A. Müll.) C.E.O. Jensen, Danmarks Mosser 2: 320. 1923.
Synonyms:
Trichostomum mutabile Bruch ex De Not., illegitimate, superfluous, Syllab. Musc. 192. 1838 ≡ Trichostomum brachydontium subsp. mutabile (Bruch ex De Not.) Giacom. illegitimate, type of species included, Ist. Bot. Reale Univ. Reale Lab. Crittog. Pavia, Atti 4: 204. 1947.
Trichostomum mutabile var.
cophocarpum Schimp., Syn. Musc. Eur. (ed. 2) 171. 1876. Type citation: “In Algarvia (H. Solms)”. Lectotype (designated by Herzog [
6]): (Portugal) Algarve, San Marcos da Serra inter cisteta c. frct!, leg. Solms, 66 (as
T. cophocarpum Solms), GOET. Isotype: 237
cophocarpum Original JE04008872! ≡
Mollia brachydontia var.
cophocarpa (Schimp.) Braithw., Brit. Moss Fl. 1: 246. 1887 ≡
Trichostomum brachydontium var.
cophocarpum (Schimp.) Cout., Musci Lusit. 36. 1917.
Hymenostomum unguiculatum H. Philib. in Schimp., Syn. Musc. Eur. (ed. 2) 37. 1876. Type citation: “in rupium calcarearum fissuris et in terra lapidosa prope Aix Gallo-Provinciae ubi clar. Prof. PHILIBERT anno 1871 detexit et ipse, eo duce, anno 1872 legi; provenit sociis Weisia viridula, Trichostomo crispulo, Bryo torquescente etc. Fruct. matur. Aprili“. Isotype: Trichostomum gymnostomum sp. nov., Aix en Provence, vere 1872, HA.H3400240!; topotype: Hymenostomum unguiculatum Philb., in rupibus calcareis umbrosis prope Aix, 29 mai 1869, HA.H3400239! ≡ Trichostomum mutabile var. unguiculatum (H. Philib. in Schimp.) Husn., Muscol. Gall. 87. 1885 ≡ Trichostomum brachydontium var. unguiculatum (H. Philib. in Schimp.) Corb. & Jahand., Ann. Soc. Hist. Nat. Toulon 4 (Suppl.): 1–63. 1920 ≡ Trichostomum viridulum (unranked) unguiculatum (H. Philib. in Schimp.) Gams & C. Cortés, invalid, rank not clearly indicated (mutsp.), Anales Inst. Bot. Cavanilles 13: 123. 1956.
Nomenclature
—Bruch mentioned two syntypes in the protologue of
Trichostomum brachydontium, one in continental Italy, “bei Spezzia”, and the other in the Italian island of Sardinia, “bei Cagliari”. Both syntypes were collected by F.A. Müller. More specifically, the Sardinian syntype was collected for “Unio Itineraria” (U.I.), also called “Botanischer Reiseverein” in Bruch’s travels to the southeastern Alps, Istria and Sardinia [
47], and to Algeria and Austro-Hungary between 1826 and 1828 [
48]. Therefore, the Sardinian syntype of
T. brachydontium is spread between many herbaria. In JE herbarium there is one exiccata of the Unio Itineraria of
T. brachydontium from Sardinia collected by F.A. Müller, in which the number of the exiccata (229a) has been added later in pencil to the label. It was studied by the authors of this work and has been selected as the lectotype. The PC sample considered an isolectotype has the same printed label as the JE specimen but was not examined by the authors of this work. In both specimens, only February is indicated as the date of collection, not the year. According to Wörz [
47], F.A. Müller traveled to Sardinia for the U.I. in 1827, and therefore that should be the year of collection. Although in the protologue Bruch indicates “März und April”, the date of the collection in the field is unknown, therefore, the non-coincidence of the months mentioned in the protologue with that indicated in the lectotype label should not be considered a reason to reject our lectotypification. In JE herbarium, there are another two specimens (JE 04008874 and JE 04005034) that could belong to the original material. In the first one, the same data as in the lectotype are handwritten and without mention of U.I., therefore it is here considered a syntype. In the JE 04005034 sample both original localities mentioned in the protologue are indicated on the label (“Sardinia in fruticetis prope Cagliari & in aggere limoso prope Golfo di Spezzia”), but as the true origin of the plants is unknown, we do not consider it a syntype.
In relation to the type of
T. b. var.
cophocarpum, Herzog [
6] (pp. 456 and 475) considered the GOET specimen to be the original material used by Schimper to describe the taxon; therefore, though not expressly mentioned, it should be considered the lectotype. Unfortunately, the specimen in GOET seems to be lost, or at least it was not found when the loan was requested. Fortunately, in the Herzog herbarium, preserved at JE, there is a small envelope without collection data, indicating only that it is the “
cophocarpum original” material. It contains two complete fructified plants. They were probably detached from the original ex GOET that Herzog took as a duplicate and kept in his herbarium, and therefore the material should be considered an isotype. In the protologue, Schimper [
46] only mentioned some characteristics in which this variety apparently differs from typical
T. brachydontium: the acute to acuminate lanceolate leaves and the ovate, more solid and brown, capsule on a short seta, and a mostly rudimentary peristome. In fact, the plants have similar leaves to those of
T. brachydontium s.s., being about 1 cm tall, greenish above and brown below, with narrowly lanceolate leaves, crispate when dry and erect-patent when moist, 2.00–2.65 × 0.33–0.55 mm (4.7 to 6.0 times as long as wide), with a short acuminate apex but not cuspidate, costa excurrent in a mucro up to 126 µm long and basal margin of leaves entire, and a sporophyte with an orange seta 7.8–8.5 mm long, ellipsoidal urn 1.10–1.20 × 0.60–0.72 mm, rudimentary peristome and spores very similar to those exemplified by
T. brachydontium s.s., and therefore it should be considered a synonym of this species. Braithwaite [
15] proposed the combination
Mollia brachydontia var.
cophocarpa (Schimp.) Braithw., but the description and comparison he made with the type species (“Plants more slender, tall, bright green above, rufescent below; leaves lanceolate below, longer, acutely acuminate; caps. on a shorter pedicel, oval, brown, peristome very rudimentary”) do not correspond to the characteristics of the original material of
T. brachydontium var.
cophocarpum, as was highlighted by Herzog [
6] (pp. 475), but to
T. brachydontium var.
cuspidatum.
Concerning the type of Hymenostomum unguiculatum H. Philib. in Schimp., the study of an isotype and a topotype kept at H herbarium revealed that these specimens correspond to T. brachydontium s.s. A third specimen at H (HA.H3400241) coming from the same locality and collected in 1874 was identified by the authors of this work as T. brachydontium var. cuspidatum, therefore it must be rejected as original material. Other original specimens of Philibert kept at AUT herbarium could not be studied but were analyzed by means of a high resolution photograph of the herbarium plate kindly sent by the AUT curator to the authors of this work. In this photograph, the size of plants, greater than 1 cm in length and the crispate median and upper leaves when dry, led us to conclude that these collections also correspond to T. brachydontium s.s. Consequently, we propose that T. brachydontium var. unguiculatum is a synonym of T. brachydontium s.s.
Morphological Description—Plants medium, (0.7-)1.0–2.0 cm tall, bright green above, brown below, in tufts; stems tomentose, several times branched by the growth of innovations, distinctly interrupted, each innovation with smaller scale-like lower leaves becoming progressively larger up stem and sometimes distinctly comose; flagelliform shoots not seen; stem cross-section rounded, 150–300 µm wide, hyalodermis irregularly present, central strand present, sometimes poorly developed; axillary hairs hyaline, up to 10 cells long, basal cell shorter; basal leaves short-triangular to ovate, apex obtuse, sharply narrowed to acute, margins entire or slightly toothed from base to apex, costa excurrent in a short mucro; median and upper leaves crispate when dry, patent to spreading when moist, the apical with the tips recurved, narrowly lingulate to narrowly lanceolate to ensiform, sometimes narrowed at base, (1.35-)1.80–3.00(-3.80) × 0.30–0.50(-0.60) mm (5.0 to 8.0 times as long as wide), lamina flat to slightly canaliculate, frequently twisted, with a more or less erect basal part, slightly sheathing the stem, but not or scarcely expanded, yellowish or hyaline, contrasting with upper part, usually markedly undulate above the basal part, sometimes slightly undulate, straight to curved, unistratose, fragile, breaking easily when dissecting; apex short-acuminate or more rarely acute; margins plane or incurved below, plane in the upper part, entire or slightly toothed in the third basal part, papillose-crenulate above; costa greenish, gradually narrowing from base to apex, 63–120 µm wide at base, excurrent in an arista, (50-)90–150 µm long, plane-convex in cross-section with two well developed stereid bands, up to 9 guide cells in the basal part of leaf and 3–4 in the upper part, one row of ventral cells and one row of dorsal cells, dorsal side of costa smooth or slightly papillose; laminal cells mid-basal and paracostals long rectangular and thin-walled, marginal basal cells longer and narrower, with 1–2 rows ascending the lamina and exceeding the transitional papillose cell area, upper cells quadrate to shortly rectangular, sometimes oblate, 5.0–6.5 × 5.0–8.0 µm, opaque, with several bifurcate, blunt papillae, frequently more developed in the ventral side, marginal cells in the median and upper part not differentiated, sometimes less papillose; dioicous?; perigonia not seen; perichaetia apical; perichaetial leaves usually similar to vegetative leaves, but internal ones narrower with longer acuminate apex. Seta (5) 10–20 mm long, yellowish; capsules ellipsoidal to cylindrical, orange, 1.20–2.20 × 0.40–0.65 mm; operculum longly rostrate, erect or inclined, 0.70–1.00 mm long; annulus persistent, formed by 3–4 rows of quadrate, thick-walled, reddish cells; peristome rudimentary to well developed, when rudimentary formed by a short smooth basal membrane, apparently absent, or by small papillose segments arising from a basal membrane, not exceeding the mouth of the urn, when well developed, formed by bifurcate, perforate, orange, papillose teeth, up to 250 µm long; spores 13–20 µm, densely and regularly warty.
Distribution and habitat—Herzog [
6] remarked on the wide and fragmented distribution of this species, centred on Macaronesia and the western Mediterranean, with occurrences from the British Isles east to the Caucasus. He listed Macaronesia (Azores, Canary Islands, Madeira), Balearic Islands, Channel Islands, Corsica, France, Great Britain (England, Scotland), Italy, Portugal, Sardinia, Spain, as well as Japan, New Zealand, and Réunion. From our study, we can confirm Macaronesia (Canary Islands), Balearic Islands, Greece, Italy, Portugal, Sardinia, Spain, and also Morocco. Its true distribution elsewhere, including North, Central, and South America, Africa, Indian Ocean Islands, and Australia [
2,
3] is uncertain because of taxonomic issues and indeed the present study has suggested further undescribed taxa (unpubl.) exist. Based on occurrences in European countries,
T. brachydontium s.l. appears to be preferential for warmer regions [
49], though surprisingly it is not reported for Gibraltar, Malta, or Netherlands. Further east, it is apparently rare or absent. It is Red Listed for Bulgaria, Estonia, Germany, Luxembourg, and Slovenia [
49]. From the present study,
T. brachydontium s.s. appears to be tolerant of a wide range of conditions, recorded from insolated situations where it is subject to periodic desiccation such as semi-fixed dunes and exposed rocks, to humid habitats including barrancos (ravines), autochthonous woodland, and on stream banks. It is apparently indifferent to substrate, from base-rich to acid, occurring on soils, protosoils, soil-filled rock crevices, on organic material (humus) and even epiphytic (on
Rhododendron in humid ravines), predominately at low to moderate elevations; material studied ranged from near sea-level to 670 m (Greece).
(1.1) Trichostomum brachydontium var. cylindricum (Schimp.) Cout., Musci Lusit. 36. 1917.
Basionym:
Trichostomum mutabile var.
cylindricum Schimp., Syn. Musc. Eur. (ed. 2) 171. 1876. Type citation: “In Algarvia (H. Solms)”. Lectotype (designated by Herzog [
6]): (Portugal) Flora Lusitanica Algarve, 110
Trichostomum mutabile Schimper … Monchique, Serra da Picota, Barranco do Banho, colleg. 1866, H. CR.Z. Solms, GOET!.
Nomenclature
—Herzog [
6] (pp. 456 and 474) considered the GOET specimen to be the original material used by Schimper to describe the taxon, and therefore we accept it as the lectotype.
Diagnostic characters—Schimper described this taxon in the protologue as having leaves slightly different from type form in leaf shape, apex, costa, and mucro and capsule oblong-cylindrical on a long seta and peristome teeth fairly regular, scarcely articulated and slightly papillose. Study of the type specimen allowed the authors of this work to ascertain that the only reliable characters of var. cylindricum that separates it from other specimens examined is the long cylindrical urn of the capsule measuring 2.0 × 0.4 mm. The other characteristics have been observed in other specimens of T. brachydontium s.s., including a long seta up to 1.5 cm and the well-developed peristome teeth, formed by bifurcate, yellowish teeth, up to 160 µm long. For the moment, we can only hypothesize that the variation in capsule size and shape may be due to environmentally induced variation, and that it should be studied further by the sequencing of other specimens with this morphology. Therefore, pending further work, we retain the taxon at varietal level.
(2)
Trichostomum herzogii Ros, O.Werner and R.D.Porley
nom. nov. (
Figure 5).
Trichostomum cuspidatum Schimp.,
nom. illeg., Syn. Musc. Eur. (ed. 2) 181. 1876. Type citation: “Ad rupes calcareas Hohenstein pr. Warstein Westphaliae socia
Solorina saccata (Dr. H. Müller)”. Lectotype (designated by Herzog [
6]): (Germany)
Trichostomum cuspidatum =
T. mutabile var.
cuspidatum Schimper, Limpr. (Synopsis ed. II), Flora von Westfalen, auf Kalkfelsen des Hohensteins bei Warburg,
leg. et mihit 111, steril (Collector unknown s.n., s.d.) (Herb. T. Herzog ex Herb. A. Geheeb) JE 04008876!. Isotypes: Westfalens Laubmoose, 205.
Trichostomum mutabile Brch., unfruchtbar, Veräntlicher Haartmund. Am Massenkalkfels des Hohenstein bei Warstein, nur unfruchtbar und mit männlichen Blüthen.
Dr. H. Müller, JE 04008877!;
Trichostomum mutabile, Warstein,
HM. 267 (Herb. Hermann Winter, Gotha), JE 04008878!.
Other names for this basionym: Mollia cuspidata Braithw., Brit. Moss Fl. 1: 230. 1887 ≡ Trichostomum mutabile var. cuspidatum (Braithw.) Limpr., Laubm. Deutschl. 1: 50. 1888 ≡ Trichostomum brachydontium subsp. cuspidatum (Braithw.) Giacom., Ist. Bot. Reale Univ. Reale Lab. Crittog. Pavia, Atti 4: 204. 1947 ≡ Trichostomum mutabile subsp. cuspidatum (Braithw.) Podp., Consp. Musc. Eur. 196. 1954 ≡ Trichostomum brachydontium var. cuspidatum (Braithw.) L.I. Savicz, Bot. Mater. Otd. Sporov. Rast. Bot. Inst. Komarova Akad. Nauk S.S.S.R. 11: 208. 1956.
Nomenclature—Herzog [
6] (pp. 477) mentioned the label data of JE 04008876 exemplar as being Schimper’s original material of
T. cuspidatum, and therefore it should be considered as the lectotype. Herzog also studied another specimen in Geheeb Herbarium (
Trichostomum mutabile Bruch, Nur steril in Klüften der Massenkalkfelsen im Lürmekethal [Lörmecketal] u. am Hohen Stein bei Warstein im Sauerland u. bei Höxter, Dr. H. Müller ex Wenck (Herb. E. Wenck), JE 04008875!), but as three localities are given on the label (prompting Herzog to annotate in pencil on the label “Woher stammt nun dieses Expl?”), the specimen should not be considered an isotype, in spite of its morphology corresponding to
T. herzogii.
Etymology—Because T. cuspidatum Schimp. is an illegitimate name and later homonym, we propose here a new name for this species in honor of the German bryologist Theodor Karl Julius Herzog (1880–1961), for his pioneering study of the T. brachydontium complex at the beginning of the 20th century. He correctly interpreted the morphological traits of this difficult and variable complex. Regrettably, his results were not taken seriously or simply ignored by his contemporaries and later workers, resulting in only one accepted species in modern bryological floras. However, some 100 years later, his approach has been vindicated by employing molecular methods.
Morphological description—Plants medium to large, (1.0-)2.0–3.0(-5.0) cm tall, yellowish green above, reddish below, in tufts; stems tomentose, several times branched, innovations not clearly differentiated, distinctly interrupted or not, each branch with lower leaves shorter than those above, becoming progressively larger up stem but not distinctly comose; flagelliform shoots sometimes present; stem cross-section rounded, 150–180 µm wide, hyalodermis irregularly present, central strand present, sometimes poorly developed; axillary hairs hyaline, up to 10 cells long, basal cell shorter; basal leaves scarcely differentiated; median and upper leaves incurved or crispate when dry (depending on the length, the longer the leaves the more crispate), erect to erect-patent when moist, the apical sometimes spreading, linear-lanceolate, (1.22-)2.00–3.45(-3.61) × (0.21-)0.35–0.50(-0.57) mm (5.0 to 7.6(-8.9) times as long as wide), lamina strongly canaliculate, not twisted, with a more or less erect basal part, sheathing the stem and expanded, concolorous with upper part, not or undulate above the basal part, straight to sigmoid, unistratose, rarely bistratose patches in the lower lamina, not fragile; apex long-acuminate to subulate; margins incurved from below to the upper part, entire or obscurely toothed in the third basal part, papillose-crenulate above; costa reddish, gradually narrowing from base to apex, 50–150 µm wide at base, excurrent in an arista, 70–150 µm long, biconvex in basal lamina cross-section, plano-convex in the rest of lamina, with two well-developed stereid bands, up to eight guide cells in the leaf base and two in the upper part, one row of ventral cells and one row of dorsal cells, dorsal side of costa smooth or slightly papillose; laminal cells mid-basal and paracostals rectangular, sometimes very narrow-rectangular, usually thick-walled, obscurely nodulose, marginal basal cells longer, narrower and thin-walled, with 2–3 rows ascending the lamina and exceeding the transitional papillose cell area, upper cells quadrate to shortly rectangular, sometimes oblate, 5.0–6.5(-8.0) × 5.0–6.5(-8.0) µm, opaque, with several bifurcate, blunt papillae, frequently more developed on the ventral side, marginal cells in the median and upper part not differentiated, sometimes less papillose and oblate; dioicous; perigonia in branch axils; perigonial leaves similar to vegetative leaves but smaller; perichaetia in branch axils; perichaetial leaves similar to vegetative leaves, sometimes with longer acuminate apex; sporophytes not seen.
Observations
—The specimens sequenced in the present work are generally larger than the types studied. In particular, the British plants from Water-Cum-Jolly Dale (DNA code 3291) attain 5 cm in length and the French plants (DNA code 3300) 3 cm, the latter specimen also having longer leaves with a higher L/W ratio, up to 8.9, whereas the German type specimens studied are 2–3 cm in length and the leaves are shorter, with a maximal length/width ratio of 7.6. The three German type specimens and a British specimen (Alberbury,
R.D. Porley 1391) include male plants, while the British specimen (DNA code 3291) includes female plants. Fully developed sporophytes have not been observed in material studied for this work, though in a French specimen from Aix en Provence (HA.H3400241), the vestige of a seta is present. Other authors (e.g., [
15]) described the sporophyte as having an oval brown capsule on a shorter pedicel, and a very rudimentary peristome, but if it corresponds to this species or
T. brachydontium s.s. is doubtful as this author confused var.
cuspidatum with var.
cophocarpum.
Distribution and habitat—In contrast to the other species, Herzog [
6] noted that this taxon is absent from the Mediterranean basin, occurring in the southern foothills of the Alps and in the mountains of Central Europe, extending east to the British Isles and to southern Sweden. He reports it is widespread within this area and gave Austria, France, Germany, Great Britain (England, Wales), Italy, Sweden, and Switzerland. The present study has confirmed it for France, Germany, Great Britain (England, Wales), and Italy. As this species has been confused with
T. brachydontium var.
cophocarpum, the distribution of
T. herzogii is incompletely known, at least in Britain.
Trichostomum brachydontium var.
cuspidatum is reported for Madeira [
11] with the caveat that all material needs revising, but its occurrence here is most unlikely. Our data regarding habitat agree with Herzog [
6] that it is characteristic of limestone cliffs, but it also occurs on damp base-rich montane rock ledges, in gorges and on calcareous rock outcrops in upland grassland, in open or partially shaded situations. Data from the few specimens we have seen indicate
T. herzogii occurs at moderate to high elevations, from c. 100 m to 950 m in Britain, but throughout its central European range it is likely to occur at higher altitudes.
(3)
Trichostomum littorale Mitt., J. Bot. 6: 99. pl. 77: f. 7–9. 1868 (
Figure 6).
Type citation: “Ireland (Drummond); Whitsand Bay, Cornwall (Mr. Brent, communicated by Mr. Holmes), below the cliffs, east of Hastings, in sandy ground”. Lectotype (designated here): Trichostomum mutabile Botsch (Wilson), Ireland, Div. 28, Gymnostomum tortile Schwaegr, NY 01449062!. Syntypes: (Great Britain) Trichostomum l., Whitstand Bay Cornwall, Mr. F. Brent, 3.2.68, NY 01449063!; (Great Britain) Trichostomum litorale Mitt., in large yellow patches a little East of Fairlight Down near Hastings, Sussex, W.M., July 1847, NY 01449064!.
Other names for this basionym: Mollia littoralis (Mitt.) Braithw., Brit. Moss Fl. 1: 244. 35 E. 1887 ≡ Trichostomum mutabile var. littorale (Mitt.) Dixon & Jameson, Stud. Handb. Brit. Mosses 216. 1896 ≡ Didymodon littoralis (Mitt.) Kindb., Eur. N. Amer. Bryin. 2: 275. 1897 ≡ Tortella brachydontia var. littoralis (Mitt.) C.E.O. Jensen, Danmarks Mosser 2: 321. 1923 ≡ Trichostomum brachydontium var. littorale (Mitt.) C.E.O. Jensen, Förteckn. Skand. Växt., Moss. (ed. 2). Mossor (Andra Upplagan) 25. 1937 ≡ Trichostomum mutabile subsp. littorale (Mitt.) Podp., Consp. Musc. Eur. 195. 1954.
Nomenclature—Mitten [
50] mentioned three syntypes in the protologue of
T. littorale, one from Ireland and two from the United Kingdom. The three syntypes are kept in the Mitten herbarium at NY. The syntype from Ireland (NY 01449062) is the more substantial collection and contains the largest plants, up to 3 cm high. The British syntype from Cornwall (NY 01449063) is sparse and contains smaller plants, about 1 cm high. The other British syntype, from East Sussex (NY 01449064), is also ample and of a similar size to the former. Mitten [
50] (plate 77) illustrated both plant sizes in the original publication of the species. The syntype from Ireland, although containing no information regarding collector or date, has been selected as the lectotype due to the better development of the plants. Mitten did not mention in the protologue the denticulate margins a short distance above the leaf base, possibly because the British syntypes are rather poorly developed. Nevertheless, it was later correctly highlighted in later works such as Husnot [
45], Dixon & Jameson [
16] and Herzog [
6].
Morphological description—Plants medium to large, (0.5-)1.5–3.0 cm tall, bright green above, brown below, in cushions or tufts; stems not tomentose, several times branched by the growth of innovations, distinctly interrupted and comose, each innovation with smaller scale-like lower leaves becoming progressively larger up stem, apical leaves crowded, forming a comal tuft; flagelliform shoots sometimes present, up to fascicles of 5, 2–3 mm long; stem cross-section rounded, 160–180 µm wide, hyalodermis irregularly present, central strand present, sometimes poorly developed; axillary hairs hyaline, up to 10 cells long, basal cell shorter; basal leaves short-triangular to ovate, apex obtuse, margins dentate from base to apex, costa usually not excurrent; median and upper leaves incurved or slightly crispate when dry, erect to erect-patent when moist, comal leaves spreading or with the tips recurved, lingulate or oblong-lingulate, sometimes slightly lanceolate or spatulate, slightly narrowed at base, sometimes constricted at transitional zone, (0.60-)1.00–1.90(-2.30) × 0.20–0.40(-0.50) mm (3.0 to 4.6(-6.6) times as long as wide), lamina canaliculate, not twisted, with a more or less erect basal part, slightly sheathing the stem, but not or scarcely expanded, yellowish or hyaline in an oval zone of basal part, sharply differentiated from other basal cells and contrasting with the upper part, slightly undulate above the basal part, curved to sigmoid, unistratose, rarely bistratose patches in the lower lamina, not fragile, does not break easily when dissecting; apex obtuse, mucronate, sometimes weakly cucullate; margins plane or incurved below, incurved in the upper part, usually strongly irregularly toothed in the third basal part, teeth sometimes recurved, rarely bifurcate, sometimes scarcely developed, papillose-crenulate above; costa mostly greenish, rarely red, gradually narrowing from base to apex, (40-)50–90(-125) µm wide at the base, excurrent in a mucro, 20–85 µm long, occasionally unguiculate, plane-convex in cross-section with two well developed stereid bands, up to 8 guide cells in the basal part of leaf and 3–4 in the upper part, one row of ventral cells and one row of dorsal cells, dorsal side of costa slightly to coarsely papillose, smooth at apex; laminal paracostal basal cells long rectangular, sometimes thick-walled, mid-basal cells shorter and marginal basal cells longer, narrower and thin-walled, with 1–2 rows ascending the lamina and exceeding the transitional papillose cell area, upper cells quadrate to shortly-rectangular, 5.0–8.0(-9.5) × 5.0–8.0 µm, opaque, with several bifurcate, blunt or rarely sharp papillae, more developed on the ventral side, marginal cells in the median and upper part not differentiated, sometimes less papillose; dioicous; perigonia not seen; perichaetia in leaf axils and at stem apex; perichaetial leaves acute, inner most lanceolate with acuminate apex; sporophytes not seen.
Distribution and habitat—This species is characteristic of oceanic climates, with an Atlantic distribution, on the western seaboard of Europe [
51], an observation supported by our own studies. Herzog [
6] listed Belgium, Channel Islands, France, Great Britain (England, Scotland, Wales), Ireland, Italy, and Sardinia. Mönkemeyer [
43] reported to be present also in southern and central Europe, Norway, and on Bornholm Island (Denmark). It is also reported for Madeira [
11] and Faroes [
52]. During the present study, we have seen specimens from Great Britain (England, Scotland, Wales), Ireland, Portugal, and Spain (Cádiz). Data from the present study reveal that it has a preference for sheltered niches, mostly on rock (schists, granite, syenite) in block-fields, or on soil-filled fissures on rocks and occasionally on soil, usually in shade but sometimes insolated. Typical habitats include rocky ravines, north-facing rocky mountain slopes, terrace walls, by cascades, spring-heads, and cliffs above streams, in woodlands (
Quercus spp.,
Castanea sativa) and, in Ireland, on lake-side boulders. It is also reported from coastal rocks in Faroes, Great Britain, and Norway [
52]. The material studied exhibited an elevational range from near sea-level to 815 m (Serra de Monchique, Portugal).
(4)
Trichostomum meridionale Ros, O.Werner, R.D.Porley
sp. nov. (
Figure 7 and
Figure 8).
Holotype—SPAIN. Murcia Region, Murcia, El Valle Perdido, proximidades a Santuario de la Fuensanta, 37°56′7.0″ N, 1°7′11.9″ W, 143 m a.s.l., R.M. Ros & O. Werner s.n., 14.03.2020, DNA code 3268 (MUB 60295). Isotypes: (MA, Herb. Porley).
Diagnosis—Trichostomum meridionale can be distinguished by plants 0.3–0.5(-1.0) cm tall, in dense and short turfs; stems comose; leaves incurved when dry and erect to erect-patent, or comal leaves spreading when moist, lingulate to spatulate, occasionally panduriform or lanceolate, 0.90–1.90(-2.30) × (0.20-)0.30–0.50(-0.60) mm (3.4 to 4.0 times as long as wide); lamina flat to canaliculate, slightly undulate above the basal part, straight to curved, unistratose, not fragile; apex obtuse and mucronate; margins plane or incurved below, more incurved in the upper part, entire or slightly denticulate in the third basal part; costa gradually narrowing from mid-leaf to apex, excurrent in a mucro 25–60 µm long; mid-basal and paracostal cells long rectangular and thin-walled, marginal basal cells longer and narrower; upper cells quadrate to shortly rectangular, 5.0–8.0 × 5.0–8.0 µm, opaque, with several bifurcate blunt papillae, more developed in the ventral side; dioicous; sporophyte usually present, with seta 5–10 mm long, urn ellipsoidal to cylindrical, yellow-red, 1.00–1.50 × 0.35–0.60 mm; peristome absent or rudimentary, formed by a short membrane or by small papillose segments arising from basal membrane, not exceeding the mouth of the urn, with bifurcate, perforate, hyaline to pale orange, papillose teeth, up to 55 µm long; spores 14–20 µm, densely and irregularly warty.
Paratypes—GREECE. Eastern Aegean Islands, Rhodes, ca 1.2 km SE of Moni Artamiti, ca. 240 m, T.L. Blockeel 47/027, 08.03.2018, DNA code 3227 (Herb. Blockeel, duplicate MUB 60472).
SPAIN. Murcia Region: Cartagena, Sierra Minera de Cartagena-La Unión, Rambla del Gorguel, 37°35′40.1″ N, 0°53′3.8″ W, 04.03.2020, 131 m. a.s.l., R.M. Ros, O. Werner & P. Egea Benavente s.n., DNA code 3259 (MUB 60287, Herb. Porley). Cartagena, Atamaría, camino que sube al monte de las Cenizas, en la carretera RM-514, 37°35′37.58″ N, 0°49′21.94″ W, 04.03.2020, 151 m. a.s.l., R.M. Ros, O. Werner & P. Egea Benavente s.n., DNA code 3261 (MUB 60289, Herb. Porley). Ibidem, DNA code 3260 (MUB 60288, Herb. Porley). Cartagena, Calarreona, 37°37′7.6″ N, 0°42′50′ W, 04.03.2020, 0 m. a.s.l., R.M. Ros, O. Werner & P. Egea Benavente s.n., DNA code 3262 (MUB 60290, Herb. Porley); Ibidem, DNA code 3263 (MUB 60291, Herb. Porley); Murcia, Rambla del Puerto de La Cadena, 37°54′31.46″ N, 1°9′43.75″ W, 260 m a.s.l., R.M. Ros & M. Farag s.n., 26.03.2019, DNA code 3266 (MUB 60292, Herb. Porley); Murcia, El Valle Perdido, proximidades a Santuario de la Fuensanta, 37°56′7.0″ N, 1°7′11.9″ W, 143 m a.s.l., R.M. Ros & O. Wener s.n., 14.03.2020, DNA code 3269 (MUB 60294, Herb. Porley); Las Torres de Cotillas, urbanización Los Romeros, calle I, parcela en la zona más alta, 38°00′35.76″ N, 1°14′36.77″ W, 144 m a.s.l., R.M. Ros s.n., 07.03.2020, DNA code 3264 (MUB 60293, Herb. Porley); Ibidem, 02.05.2020, DNA code 3265 (MUB 60296, Herb. Porley).
Synonyms—Trichostomum mutabile var. densum Bruch & Schimp., Bryol. Eur. 2: 122. pl. 174: B (fasc. 18–20. Mon. 16. pl. 5: B). 1843 ≡ Trichostomum mutabile subsp. densum (Bruch & Schimp.) J.J. Amann, Fl. Mouss. Suisse 2: 96. 1918 ≡ Trichostomum brachydontium subsp. densum (Bruch & Schimp.) Giacom., Ist. Bot. Reale Univ. Reale Lab. Crittog. Pavia, Atti 4: 204. 1947 ≡ Trichostomum brachydontium var. densum (Bruch & Schimp.) Düll, Bryol. Beitr. 4: 90. 1984. Type not seen.
Nomenclature—Cortes Latorre [
53] and Esteve Chueca and Cortes Latorre [
54] reported
Trichostomum brachydontium var.
unguiculatum (H. Philib. in Schimp.) Corb. & Jahand. from the Murcian littoral mountains in the neighborhood of Cartagena (SE Spain), a taxon described in Schimper [
46] from Aix en Provence (France) as
Hymenostomum unguiculatum H. Philib. in Schimp. The latter, as explained in the nomenclature section of
T. brachydontium s.s., is here considered a synonym of the former species.
Morphological description—Plants small, 0.3–0.5(-1.0) cm tall, bright green above, yellow to brown below, in dense and short turfs; stems not tomentose, not or scarcely branched by the growth of innovations, distinctly interrupted or not (depending on the size of plants, when very short than not distinctly interrupted) and comose, each innovation with smaller lower leaves becoming progressively larger up stem, the apical leaves crowded forming a comal tuft; flagelliform shoots not seen; stem cross-section rounded, up to 140 µm wide, hyalodermis irregularly present, central strand well developed; axillary hairs hyaline, up to 10 cells long, basal cells shorter; basal leaves short-triangular, apex acute, margins entire or slightly toothed from base to apex, costa ending below apex or excurrent in a short mucro; median and upper leaves incurved when dry, erect-patent to patent, comal leaves more rarely spreading when moist, lingulate to spatulate, occasionally panduriform or lanceolate, 0.90–1.90(-2.30) × (0.20-0.30–0.50(-0.60) mm (3.4 to 4.0 times as long as wide), lamina flat to canaliculate, not twisted, with basal part not or slightly sheathing the stem, not or scarcely expanded, yellowish or hyaline, contrasting with upper part, slightly undulate above the basal part, straight to curved, unistratose, not fragile, does not break easily when dissecting; apex obtuse, mucronate; margins plane or incurved below, more incurved in the upper part, entire or slightly toothed in the third basal part, papillose-crenulate above; costa mostly greenish, rarely red, gradually narrowing from mid-leaf to apex, (65-)80–100(-140) µm wide at base, excurrent in a mucro, 25–60 µm long, plane-convex in cross-section with two well developed stereid bands, up to 6 guide cells in the basal part and 3–4 in the upper part, one row of ventral cells and one row of dorsal cells, dorsal side of costa slightly to coarsely papillose to the apex; laminal cells mid-basal and paracostals long-rectangular and thin-walled, marginal basal cells longer and narrower, with 1–2 rows ascending the lamina and exceeding the transitional papillose cell area, upper cells quadrate to shortly rectangular, 5.0–8.0 × 5.0–8.0 µm, opaque, with several bifurcate blunt papillae, more developed on the ventral side, marginal cells in the median and upper part not differentiated; dioicous; perigonia subapical; perigonial leaves similar to vegetative leaves but smaller; perichaetia apical; perichaetial leaves usually similar to vegetative leaves, occasionally heteromorphic, with one leaf narrower and longer than the other, or sometimes smaller; seta 5–10 mm long, yellowish; capsule ellipsoidal to cylindrical, yellow-reddish to brownish, 1.00–1.50 × 0.35–0.60 mm; operculum long-conical to rostrate, erect or inclined, 0.60–0.70 mm long; annulus persistent, formed by 3–5 rows of quadrate, thick-walled, reddish cells; peristome absent to rudimentary formed by a short papillose basal membrane or by small segments arising from basal membrane, not exceeding the mouth of the urn, bifurcate, perforate, hyaline to pale orange, papillose, up to 55 µm long; spores 14–20 µm, densely and irregularly warty.
Distribution and habitat—Of the four species,
T. meridionale clearly occupies the narrowest distribution and ecological niche. Its known range includes Macaronesia (Canary Islands) and on the shores of the Mediterranean including Corsica, Italy (Tuscany), and Sardinia [
6].
Trichostomum brachydontium var.
densum is reported in southern Europe [
43], and more precisely Balearic Islands and Spain [
7,
8]. The present study has confirmed its presence in southern Spain (Alicante, Almería, and Murcia provinces), Greece (Eastern Aegean Islands), and Sardinia. It is more or less confined to open coastal scrubland, including phrygana and garigue, on relatively alkaline and calcareous soils in the Mediterranean bioclimatic zone. The material studied shows an elevational range from sea-level to 650 m (Spain).