Porotrichum lancifrons (Hampe) Mitt.

Authority

Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.

Family

Neckeraceae

Scientific Name

Porotrichum lancifrons (Hampe) Mitt.

Description

Species Description - Plants robust, to 8(-13) cm tall, stipitate-frondose, the stipe at times longer than the frond, in pale- to dark-green, wiry, sparse colonies. Primary stems creeping, secondary stems mostly arising from upturning primary stem, the creeping stem continuing by innovations near the base of the stipe, the secondary stems prominently stipitate, to ca. 6 cm tall, mostly erect, frondose, irregularly but strongly 2-pinnate to weakly 3-pinnate, usually complanate-foliate; in cross-section with 2-3 rows of small thick-walled cells, with 4-5 rows in stipe, surrounding large firm-walled cells, central strand present, of small very thin-walled cells; paraphyllia absent; pseudoparaphyllia broadly foliose; axillary hairs with 1-2 short brown basal cells and 2-3 elongate hyaline distal cells. Primary creeping stem leaves not seen, reportedly (Sastre-De Jesús, 1987) erect, broadly ovate, 1 X 0.9 mm, acute; margins entire; cells linear. Stipe leaves widely spaced, strongly appressed, hyaline (at least at maturity if not earlier), not complanate, oblong, 1-2 mm long, obtuse-cuspidate; margins subentire throughout, plane; costa single, ending ca. 2/3 the leaf length, not projecting at apex; cells linear-fusiform, 8-15:1, smooth, firm-walled, ± porose; alar cells not differentiated from rectangular cells all across the insertion. Secondary stem (continuation of stipe above branching) leaves complanate, spreading, oblong-ovate, 2.8-3.6 mm long, acute-apiculate; margins serrate with mostly unicellular teeth in upper 1/3-1/2, subserrulate to subentire below, plane; costa single, ending 2/3-5/8 the leaf length, not or scarcely projecting at apex; cells fusiform, 5-8(-10): 1, smooth, thin- to firm-walled, not or scarcely porose, apically becoming shorter and rhombic, 2-3:1, becoming longer and broader toward the insertion, at the insertion very thick-walled and porose; alar cells not or scarcely differentiated. Branch leaves spreading, complanate, oblong-ovate, 1-1.5 mm long, acute-apiculate, concave at base; margins serrate above with the teeth 1-3-celled, serrate to serrulate almost to base, plane to erect; costa single, ending 2/3-3/4 the leaf length, not or scarcely projecting at apex; cells fusiform, 6-10:1, smooth, thin- to firm-walled, not porose. Asexual propagula not seen, but branch leaves sometimes caducous. Dioicous. Perichaetia pale, on secondary stems and bases of branches; leaves appressed with spreading apices, oblong, 1.2-1.9 mm long, abruptly long-acuminate, the acumen ca. 1/3, the leaf length; margins subentire, plane; costa none or single and very short; cells broadly fusiform, 7-10:1, smooth, firm-walled, ± porose, becoming longer and narrower in the acumen, becoming thicker-walled and strongly porose toward the insertion. Setae short to elongate, stout, smooth, reddish, 3.5-8 mm long (or apparently to 3 cm extralimitally); capsules erect, broadly short-cylindric, symmetric, 1.8-2(-3) mm long; exothecial cells short-rectangular, firm- to thick-walled, becoming subquadrate and thinner-walled at the mouth; annulus of 2-3 rows of oblong thick-walled cells; operculum obliquely rostrate from a conic base, ca. 1.5 mm long; exostome teeth on the front surface cross-striolate below, usually with some overlying papillae, coarsely papillose above, somewhat trabeculate at back; endostome with a high, ± smooth papillose basal membrane, segments papillose, keeled, broadly perforate, almost as long as the teeth, cilia in groups of 2(-3), papillose, almost as long as the segments. Spores spherical, densely high-papillose, 11-17 diam. Calyptrae not seen (but vaginula ± naked).

Discussion

5. Porotrichum lancifrons (Hampe) Mitt., J. Linn. Soc., Bot. 12: 462. 1869; Hypnum lancifrons Hampe, Linnaea 32: 158. 1863; Thamnium lancifrons (Hampe) Kindb., Hedwigia 41: 235. 1902; Porothamnium lancifrons (Hampe) M. Fleisch. ex Broth, in Engl., Nat. Pflanzen-fam., ed. 2, 11: 199. 1925. Plate 50, figures 1-10 Hypnum neckeraeforme Hampe, Ann. Sci. Nat. Bot. V, 5: 309. 1866; Porotrichum neckeraeforme (Hampe) Mitt., J. Linn. Soc., Bot. 12: 464. 1869; Thamnium neckeraeforme (Hampe) Kindb., Hedwigia 41: 226. 1902; Porothamnium neckeraeforme (Hampe) M. Fleisch. ex Broth, in Engl., Nat. Pflanzenfam., ed. 2, 11: 199. 1925. Porotrichum crassipes Renauld & Cardot, Bull. Soc. Roy. Bot. Belgique 32(1): 185. 1894; Porothamnium crassipes (Renauld & Cardot) M. Fleisch. ex Broth. in Engl., Nat. Pflanzenfam., ed. 2, 11: 199. 1925. Porotrichum ramosissimum Hampe, Vidensk. Meddel. Dansk Naturhist. Foren. Kjøbenhavn III, 6: 155. 1874 [1875]; Thamnium ramosissimum (Hampe) Kindb., Hedwigia 41: 241. 1902; Porothamnium ramosissimum (Hampe) M. Fleisch. ex Broth, in Engl., Nat. Pflanzenfam., ed. 2, 11: 199. 1925. Discussion. This uncommon species is the most handsome member of Porotrichum in our flora. It is characterized by a well-developed stipe, at times over half the total plant height, and strongly appressed, hyaline stipe leaves. The branch leaves are coarsely toothed above and less strongly so nearly to the leaf base. Because of cross-striolate exostome teeth, Porotrichum lancifrons has been assigned to Porothamnium. However, because of the lack of any correlative gametophytic characters, and the number of species only known sterile, I am reluctant to accord generic status to what I think is minor, perhaps habitat-driven, peristome variation. Until I have additional evidence, I suspect that species in Porotrichum, such as P. lancifrons, that are primarily terrestrial should have better developed exostomes than obligately epiphytic species. Without gametophytic characters to correlate with sporophytic differences, there is no reason to assume that peristome-defined assemblages are monophyletic.

Distribution

Range. Mexico, Costa Rica, Venezuela, Colombia, Bolivia, southeastern Brazil; Cuba, Jamaica, Hispaniola (Dominican Republic); growing on tree trunks or more typically humus, in humid hardwood forests, at 1800-2200 m.

Mexico North America| Costa Rica South America| Venezuela South America| Colombia South America| Bolivia South America| Brazil South America| Cuba South America| Jamaica South America| Dominican Republic South America|