Monographs Details: Fissidens ornatus Herzog
Authority: Pursell, Ronald A. 2007. Fissidentaceae. Fl. Neotrop. Monogr. 101 (Published by NYBG Press)
Scientific Name:Fissidens ornatus Herzog
Description:Species Description - Plants dark green, usually somewhat reddish, persistent protonemata infrequent. Stems monomorphic, unbranched, 2.5-6 mm long x 1.5-2.5 mm wide; rhizoids basal, smooth, sometimes papillose, tan to reddish; axillary hyaline nodules absent; epidermis and outer 1-2 tiers of cortical cells small, incrassate, pigmented; inner cortical cells larger, thin-walled, hyaline; central strand present. Leaves ± crispate, usually ± rolled inward longitudinally toward costa when dry, usually distant, as many as 14 pairs, lancolate, sometimes oblong, proximal ones scale-like, acute, infrequently rounded-obtuse, apex asymmetric, dorsal side extended further upward than ventral side or symmetric with both sides extended equally, 12 mm long x 0.2-0.4 mm wide, perichaetial leaves usually largest; margin serrate, limbate and entire on proximal 1/2 or less of vaginant laminae of most leaves, limbidium usually broad, developed best on perichaetial and subtending leaves, limbidial cells unistratose; costa subpercurrent to percurrent to short- to long-excurrent, bryoides type; dorsal lamina usually rounded, ending at insertion; vaginant laminae of cauline leaves 1/3-3/4 leaf length, acute, unequal, minor lamina distally rounded and free, or narrowed and ending on costa, or ending intermediate between costa and margin, broad, retuse in perichaetial and perigonial leaves; laminal cells distinct, guttulate, unistratose, smooth, ± bulging, dimorphic, inner cells ± oblong to hexagonal, 18-40 µm long x 13-18 µm wide, marginal 1-3 rows conspicuously smaller, 6-14 µm long. Monoicous (rhizautoicous); perigonia and perichaetia terminal on stems of similar size. Sporophytes 1 per perichaetium, yellow, darkening with age; seta smooth, 1.5-3 mm long; theca exserted, erect, ± bilaterally symmetric, 0.65 mm long, stomatose, exothecial cells quadrate, collenchymatous; peristome scariosus type; operculum conic, long-rostrate, to 0.4 mm long. Spores smooth, 9-13 µm diam. Calyptra smooth, cucullate, 0.5 mm long.

Discussion:Fissidens ornatus is distinctive by its laminai cells of two distinct sizes, the outer 1-3 rows conspicuously much smaller than the interior cells. In addition, the vaginant laminae of perichaetial and perigonial leaves are broad, retuse, and limbate. The minor lamina of the unequal vaginant laminae in the cauline leaves is acute or either narrowed and ending on the costa or rounded and free. The limbidium is best developed on the perigonial and perichaetial leaves although it is present on other leaves, even those of infertile stems. Although the costa is typically excurrent, often long-excurrent, infrequently it can be percurrent or shorter in length. The species is close to F. inaequalis which has similar laminal cells and vaginant laminae but is elimbate, and the costa typically ends below the obtuse to obtuse-apiculate leaf apex. Fissidens omatus shares a number of characteristics with F. saülensis and F. subulatus, such as an asymmetric leaf apex, a limbidium, and a long-excurrent costa. However, the laminal cells of F. saülensis, similar to those found in F. pellucidus, are more or less regularly hexagonal and less distinctly dimorphic. In F. subulatus the dorsal lamina of most or all leaves is either greatly reduced or absent, particularly in the scale-like proximal leaves. In some expressions of F. omatus the lower leaves can also be scale-like but the dorsal lamina is well developed in most leaves. Whereas sporophytes are usually profusely produced in F. saülensis and F. subulatus, they are rare in F. ornatus. In over 50 specimens examined, only four had sporophytes, and no gemmae were observed, which makes the wide distribution of the species difficult to explain. Guttulae are not always seen in the laminal cells of F. omatus, and protonemata are infrequently seen, perhaps because of the condition of the substrata in most collections.
Distribution:Saint-Laurent-du-Maroni French Guiana South America| Guadeloupe South America| Colón Panama Central America| Darién Panamá Central America| Panamá Panama Central America| Jamaica South America| Puerto Rico South America| Antioquia Colombia South America| Zulia Venezuela South America| Brokopondo Suriname South America| Sipaliwini Suriname South America| Cayenne French Guiana South America| Acre Brazil South America| Alagoas Brazil South America| Amazonas Brazil South America| Pará Brazil South America| Pernambuco Brazil South America| Rondônia Brazil South America| Roraima Brazil South America| Beni Bolivia South America| Trinidad and Tobago South America|