Small Fronds Research Articles

A New Species of Ceradenia (Polypodiaceae) from Southern Brazil

Abstract A new species from the highlands of southern Brazil, Ceradenia maackii, is described and compared to its most similar species. The new species is characterized by having small fronds, ciliate rhizome scales, petiole, axes, and laminar tissue without setae, and laminar tissue bluish and densely covered by glandular hairs. Ceradenia maackii is epipetric and known only from “Pico do Parana” State Park. The new species is illustrated, and a key for Ceradenia from the Atlantic Rain Forest is also provided.

Differences in the structure and functioning of two communities: Frondose and turf-forming macroalgal dominated habitats

In many coastal regions, vegetated habitats (e.g. kelps forests, seagrass beds) play a key role in the structure and functioning of shallow subtidal reef ecosystems, by modifying local environmental conditions and by providing food and habitat for a wide range of organisms. In some regions of the world, however, such idiosyncratic ecosystems are largely absent and are often replaced by less notable ecosystem formers. In the present study, we empirically compared the structure and functioning of two distinct shallow-water habitats present in the Azores: one dominated by smaller frondose brown macroalgae (Dictyotaceae and Halopteris) and one dominated by low-lying turfs. Two replicated areas of each habitat were sampled at two different times of the year, to assess spatial and temporal consistency of results. Habitats dominated by small fronds were significantly (ca. 3 times) more productive (when standardized per algal mass) compared to the turf-dominated habitats, and supported a distinct assemblage (both in terms of composition and abundance) of associated macrofauna. Unlike other well-known and studied vegetated habitats (i.e. kelp forests), however, no effects of habitat were found on the structure of benthonic fish assemblages. Results were spatially and temporally consistent suggesting that, in warmer temperate oceans, habitats dominated by species of smaller frondose brown algae can also play an important role in the structure and functioning of subtidal communities and may, to a certain extent, be considered analogous to other well-known vegetated habitats around the world (i.e. kelp forests, seagrass beds).

Two new Ediacaran small fronds from Mistaken Point, Newfoundland

AbstractSmall, stemmed frond fossils are common in Ediacaran-aged strata (ca. 565Ma) at Mistaken Point, Newfoundland, and many of them have previously been informally referred to as ‘dusters,’ but due to their small size and consequent relatively poor preservation, they have not yet been described taxonomically. Two new genera are herein defined on the basis of their unique constructions: the mop-like rangeomorphPlumeropriscum hofmanninew genus new species, and a flabellate, lobate frondBroccoliforma altanew genus new species.Plumeropriscum hofmannin. gen., n. sp. has a three-dimensional petalodium structure with numerous primary branches attached at the base of the petalodium rather than at a central axis.Broccoliforma altan. gen., n. sp. lacks visible branching, and instead has a lobate morphology with a petalodium that is at least superficially similar to the ivesheadiomorphBlackbrookia. Several other previously described taxa had also been included under the umbrella of ‘dusters.’ Collectively, these taxa show that the low epibenthic tier that small fronds occupied was more diverse than previously realized, with multiple taxa converging on the stemmed, small-frond body plan.

The calcareous brown alga Padina pavonica in southern Britain: population change and tenacity over 300years.

Understanding long-term persistence and variability in species populations can help to predict future survival, growth and distribution; however, sustained observations are exceedingly rare. We examine and interpret a remarkable record of the calcareous brown alga Padina pavonica (Phaeophyceae) at its northern limit on the south coast of England (50°N, 1–3°W) from 1680 to 2014, which is probably the longest compilation and review of any marine algal species. Over this period, which extends from the middle of the Little Ice Age to the present, there has been considerable variability in temperature and storminess. We identified a significant number of site extinctions in the second half of the nineteenth century, which coincided with cooler conditions and stormier weather. To interpret these changes, we measured recruitment, growth and production of tetraspores at sheltered and exposed sites in 2012–2014, years which had low and high spring temperatures. Potential spore production was greater at the sheltered site due to a longer growing period and survival of larger fronds. Delayed growth in the cooler spring resulted in smaller fronds and lower potential production of tetraspores by early summer. Yet in the warmer year, rapid initial growth caused higher sensitivity to damage and dislodgement by summer storms, which also limited potential spore production. Antagonistic responses to multiple stressors and disturbances make future predictions of survival and distribution difficult. Fronds of Padinapavonica are sensitive to both temperature and physical disturbances, yet vegetative perennation appears to have enabled population persistence and explained the longevity of remaining populations.Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-015-2805-7) contains supplementary material, which is available to authorized users.

Costly leaf shelters protect moth pupae from parasitoids

Many caterpillars construct shelters by folding leaves and feeding from within. Many shelter-constructing species suffer high rates of parasitism as larvae or pupae. In spite of the likely significance, the effects of these shelters on the survival of pupae and the trade-off between feeding and constructing shelters have attracted little experimental attention. In both field and laboratory experiments, fern-feeding caterpillars [Herpetogramma theseusalis (Walker) (Lepidoptera: Crambidae)] invested heavily in shelters, losing weight and significantly delaying pupation rather than feeding or pupating in exposed locations. Experimentally thinning the walls of shelters in the field doubled the parasitism rate. Parasitism of pupae exceeded predation by an order of magnitude or more in both seasons of this study. Caterpillars constructed similarly sized shelters regardless of availability of fern fronds, resulting in incomplete shelters on especially small fronds, putting pupae at increased risk of parasitism. We suggest that similar interactions are common and merit more attention.

Ecological Responses of Osmunda regalis to Forest Canopy Cover and Grazing

Abstract The density and frond traits of the dimorphic fern Osmunda regalis were examined in 45 populations situated in central Italy, along a gradient of forest canopy cover and deer grazing. The survey involved 1704 ramets containing 6416 fronds, of which 5643 were sterile and 773 fertile. Within the ramets, the number of fertile fronds increased with the number of sterile fronds and with the mean height of ramets. Light seemed to promote fertility, as the number of fertile fronds decreased with increasing canopy cover. Fewer and smaller fronds were found in plots with high forest canopy cover. Our results showed that O. regalis performed best in conditions of full sunlight but can persist and recruit young sporophytes under closed canopy. As many marsh and lake environments have disappeared or been altered by human activity, more populations were located under high canopy cover in the forest than in open habitats. Deer grazing caused a significant decrease in fertile fronds, in total frond area and in ...

SELF-THINNING AND SIZE INEQUALITY DYNAMICS IN A CLONAL SEAWEED (SARGASSUM LAPAZEANUM, PHAEOPHYCEAE)(1).

Fronds of clonal seaweeds with extensive holdfasts relative to frond size are known not to self-thin during growth, even in crowded stands. We tested whether frond self-thinning would occur for such a seaweed since these traits are more similar to those of unitary seaweeds, which do self-thin in crowded conditions. We used Sargassum lapazeanum Setch. et N. L. Gardner (Fucales, Phaeophyceae) from the Pacific coast of Mexico, for which we first confirmed its clonal nature by performing a regeneration experiment in culture tanks. During the growth season (winter to late spring), S.lapazeanum stand biomass increased, while frond density and size inequality (Gini coefficient for frond biomass) decreased. These results indicate that self-thinning occurred at the frond level. We propose a conceptual model for frond dynamics for clonal seaweeds in general. In stands of clonal species with small fronds and relatively extensive holdfasts (particularly when holdfasts are perennial), frond dynamics would be determined mostly by intraclonal regulation, which seems to prevent excessive crowding from occurring. Such species display a positive biomass-density relationship during the growth season. On the contrary, in stands of clonal species with large fronds relative to holdfast size, frond dynamics would be determined mostly by interactions among genets. For such species, self-thinning may be detected at the frond level in crowded stands, resulting in a negative biomass-density relationship during growth.

Intrinsic factors influence the attachment of fragments of the green alga Caulerpa filiformis

Asexual reproduction via fragmentation is an integral component of the life history of many marine organisms. In south-eastern Australia the green macroalga Caulerpa filiformis (Suhr) Hering is abundant on many rocky shorelines and fragments are very abundant in the water column. We examined some of the factors that may influence the growth and successful reattachment of fragments of C. filiformis that potentially contribute to its success. Field surveys revealed that C. filiformis fragments were of variable morphologies (from small fronds to entire thalli) and sizes (0.1–60 cm in length). All fragments of C. filiformis were viable propagules that survived and grew well in the laboratory. However, some fragments grew more than others, in particular larger sizes (7.5 cm class) of certain morphologies (fragments that consisted only of a single frond). Rhizoids were produced by all fragments, but again, larger fragments produced more rhizoids than smaller fragments. The force required to detach fragments was proportional to the number (but not size) of rhizoids, demonstrating the importance of rhizoids for attachment. The rate of attachment of fragments was also fast, usually within 12 h, but the longer these fragments were attached to a substratum the greater the force required to dislodge them. Interestingly, fragments only produced rhizoids if they were resting on a substratum which may explain the small proportion of fragments with rhizoids in the field (< 5%). Ultimately, the long term success of C. filiformis fragments was low as only 1.6% of fragments attached within 24 h and none of these persisted for longer than 2 days. Nonetheless, the abundance and viability of fragments of C. filiformis available to attach suggest that asexual fragmentation is a successful reproductive strategy in this seaweed.

Population dynamics of Sargassum lapazeanum (Fucales, Phaeophyta) from the Gulf of California, Mexico

M. Rivera and R. Scrosati. 2006. Population dynamics of Sargassum lapazeanum (Fucales, Phaeophyta) from the Gulf of California, Mexico. Phycologia 45: 178–189. DOI: 10.2216/05-47.1We studied the population dynamics of Sargassum lapazeanum from the southwestern Gulf of California, Mexico, between February 2000 and February 2001. We qua.gified the seasonal changes in frond density, stand biomass, frond size structure and inequality, presence of reproductive structures, and rates of recruitment, growth, and mortality. Fronds were present during the entire year, although with a marked seasonality: mean frond density, frond length, and stand biomass were highest in spring and lowest in winter. The strong increase in frond density between winter and spring resulted from the combination of high recruitment and low mortality rates. Growth rates were highest in spring; the highest absolute value (3.6 cm d−1) is among the highest found for brown seaweeds. The frond size structure became best developed in late spring. Reproductive structures peaked in abundance in late spring and became mostly lost by late summer. Senescence started in late spring and increased dramatically during the summer. The strong decrease in frond density between summer and autumn resulted from the combination of low recruitment and high mortality rates. In early autumn, primarily only small fronds remained in the population, including new recruits and remnants of previously large fronds. The seasonal pattern in the temporal abundance changes for S. lapazeanum agrees with a general model proposed for subtropical species of this genus.

Urothelial Papilloma of the Bladder

Urothelial papilloma of the bladder is an uncommon entity when using restrictive diagnostic criteria. We retrospectively studied 34 patients who were diagnosed with urothelial papilloma of the bladder using the criteria of the 1998 WHO/ISUP classification system. Six cases were in-house and the remaining 28 were referred from other institutions as consults to one of the authors. In all cases, the diagnosis of papilloma was the first manifestation of urothelial neoplasia. The mean age of the patients at diagnosis was 57.8 years (range, 23-87 years). The male-to-female ratio was 2.4:1 (24 males and 10 females). The tumor size averaged 3.3 mm (range, 1-20 mm; median, 2 mm). Simple papillary fronds were seen in all cases; in 5 cases the additional finding of secondary budding off of small fronds from larger ones was also seen. In all cases, the fronds had a round morphology; yet in 4 cases elongated fronds were also noted. In 5 cases, dilated lymphatics within the fibrovascular fronds were apparent. One case had foamy histiocytes within the fibrovascular stalks. In all cases, the lining consisted of normal-appearing urothelium without hyperplasia, dysplasia, and/or mitotic figures. Some of the distinctive histologic features seen were changes in the umbrella cells: vacuolization (n = 4), prominence with cytologic atypia (n = 2), eosinophilic syncytial morphology (n = 1), apocrine-like morphology (n = 1), and mucinous metaplasia (n = 1). Follow-up was available in 26 cases with a mean follow-up for those without evidence of progression of 28.9 months (range, 3-127 months). Three patients (8.8%) developed recurrent papilloma 4, 15, and 18 months after the initial diagnosis of papilloma; 1 of these patients also showed progression to noninvasive low-grade urothelial carcinoma at the time of recurrence (15 months). Three patients (8.8%) progressed to higher-grade disease: 2 to noninvasive low grade urothelial carcinoma (11 and 15 months after the original diagnosis) and 1 to a papillary urothelial neoplasm of low malignant potential at 104 months and a noninvasive low-grade urothelial carcinoma at 141 months from the initial diagnosis of papilloma. None of the patients demonstrated progression to either lamina propria (T1) or muscularis propria (T2) invasion. Two patients died of unrelated causes. None of the patients died of bladder cancer. Patients with urothelial papillomas have a low incidence of recurrence and rarely progress to develop urothelial carcinoma. It seems reasonable to avoid labeling these patients as having cancer. It remains to be studied whether and when patients with papillomas who have no evidence of recurrence or progression no longer need to be followed.

Approach to benign duodenal polyps

Approach to benign duodenal polyps

Timing and frequency of perioperative carotid color-flow duplex scanning: A preliminary report

Purpose: The results of intraoperative and early postoperative carotid color-flow duplex scanning (CFS) after endarterectomy were reviewed to determine whether any perioperative studies could be eliminated. Methods: Patients undergoing carotid endarterectomy with intraoperative CFS between 1986 and 1997 were identified. Early postoperative CFS was performed between 1 day and 3 weeks postoperatively, then it was performed again at 6 months postoperatively. Results: During the study period, 560 patients, 325 men and 235 women, underwent 621 carotid endarterectomies. A satisfactory intraoperative carotid CFS was completed in 611 (98.4%) patients. There were 20 (3.2%) vessels with a major defect that required revision for fronds or flaps (n = 11), retained atheroma (n = 5), low flow (n = 2), high velocity or turbulence (n = 1), or dissection (n = 1). Another 146 vessels (23.5%) had minor defects, such as retained proximal atheromas or small (less than 3 mm) fronds, but were not revised. The remaining 445 vessels were normal. The first postoperative CFS was normal in all the revised carotids and in 138 (94.5%) vessels with minor intraoperative defects. At 6 months, recurrent stenosis (more than 75% area reduction) was identified in 1 of 18 revised carotids (5.5%), 4 of 138 vessels (2.9%) with minor defects, and 17 of 406 vessels (4.2%) that were normal intraoperatively. The incidence of recurrent stenosis was not significantly different in the three groups ( P = .7). Conclusion: Intraoperative CFS is useful because major unsuspected defects can be corrected immediately, thus avoiding potential neurologic morbidity. However, the postoperative day 1 CFS can be eliminated in most cases, because it does not provide any relevant clinical information. (J Vasc Surg 1999;29:833-7.)

Morphological Variation inFucus VesiculosusPopulations along Temperature and Salinity Gradients in Iceland.

Geographical morphological variations inFucus vesiculosuspopulations were studied along the coast of Iceland. Principal component analysis (PCA) based on 11 morphological characters clustered the 26 sampling sites into four different morphological types as follows: (1) a morphological type found along the S-SW-W coast; (2) an intermediate form comprising only two populations in the NW; (3) a type found along the N-NE-E-SE coast; and (4) a type found independent of geographical area, in estuaries and at sites influenced by large freshwater outflows. Populations influenced by low salinity had significantly (P≤ 0·001) shorter thalli, a shorter distance from the holdfast to the oldest dichotomy, smaller fronds, narrower stipes and midrib width compared to the morphology of all other more saline populations. No significant difference in frond width was found between the S-SW-W and the N-NE-E-SE populations. However, significant (P≤ 0·001) morphological differences between them were observed, the former having shorter thalli, a greater distance from the holdfast to the oldest dichotomy, narrower stipes and smaller midrib width compared to the latter.

Fecundity, spore recruitment and size in Gelidium sesquipedale (Gelidiales, Rhodophyta)

Gelidium sesquipedale fecundity was quantified by counting tetrasporangial sori and cystocarps per meter squared and by estimating the number of spores contained inside them. These were obtained by regression on a size metric of reproductive structures. Tetrasporangial sori length and cystocarp thickness were the best estimators of spore number. To assess spore recruitment, 12 pottery tiles were fixed to the bottom, and the appearance of small fronds was monitored.No clear seasonal pattern of reproduction was found. Tetraspore production peaked in March 1990 with 10.4 × 106 spores m−2, whereas the carpospore peak was lower, 4.9 × 105 spores m−2 in July 1989. Recruitment followed tetraspore peaks. The probability of a G. sesquipedale tetraspore making the transition to a recruit was 4.7 × 10−5. Frond length was significantly related to tetrasporangial sori number, while cystocarp number was only related to frond branching order. Minimum size for reproduction was 6.9 cm for gametophytes and 5.4 cm for tetrasporophytes; very rarely were cystocarpic fronds smaller than 9 cm, while tetrasporic fronds were often longer than 15 cm. Cystocarpic fronds were significantly shorter and had more branches than tetrasporic fronds.

Jania (Corallinales, Rhodophyta) in southern Australia

The coralline algal genus Jania Lamouroux (tribe Janieae, subfamily Corallinoideae, family Corallinaceae) contains six species on southern Australian coasts: J. micrarthrodia Lamouroux, J. pulchella (Harvey) comb. nov., J. pusilla (Sonder) Yendo, J. verrucosa Lamouroux, and two new species, J. minuta and J. parva. These species are segregated primarily on vegetative characters pertaining to fronds, intergenicula, branching, medullary organisation, and substrate preference, with reproductive features used in some cases. Four of the species are, as far as known, endemic to southern Australia: J. minuta, J. pawa, J. pulchella, and J. pusilla. Jania minuta and J. rnicrarthrodia have evolved a unique short-segmented morphology, with intergenicula containing only one or two tiers of medullary cells each. Jania micrarthrodia is a common and conspicuous epiphyte and variable in morphology depending on degree of water movement. In J. minuta, tetrasporangia are replaced by unusual sporangia, each comprised of a large two-nucleate cell, bracketed by small, uninucleate apical and basal cells. This species also forms distinctive multicellular propagules. Jania parva has delicate fronds with dichotomies that tend to diverge widely; only bisporangial and gametangial plants have been found. Jania pulchella has two types of intergenicula, 'janioid' intergenicula which in fertile plants contain conceptacles, and basal compressed and lobed 'cheilosporoid' intergenicula; it is transferred from Cheilosporum pulchellum Harvey. Jania pusilla is usually epiphytic on Cystophora spp., and has small fronds with broad intergenicula. Jania verrucosa, the most robust species, forms dense tufts on low intertidal rocks in southern Australia and in other subtropical or temperate regions.

Thick vs. thin: thallus morphology and tissue mechanics influence differential drag and dislodgement of two co-dominant seaweeds

The lower rocky intertidal zone of many moderately exposed and exposed shores in the Gulf of Maine, USA, is co-dominated by two species of red macroalgae, Chondrus crispus Stackhouse and Mastocarpus stellatus (Stack. in With.) Guiry. These species are anatomically, morphologically, ecologically and phylogenetically similar. We quantified: 1. (1) mechanical properties of the stipe; and 2. (2) flow forces on the stipe relative to thallus area and biomass of these species, to determine mechanical and morphological characteristics that could explain the greater winter dislodgement of C. crispus thalli in mixed stands. Although stipes of both species broke at the same mean force, C. crispus stipes were relatively thick, weak and extensible compared to the relatively thin, strong and stiff stipes of M. stellatus. Risk of breakage increased with size in both species because: 1. (1) their stipes weakened with increasing cross-sectional area; and 2. (2) cross-sectional area of the stipe failed to increase in linear proportion to frond area. Drag on C. crispus thalli of > 3 g fresh weight was greater than on M. stellatus of the same biomass, whereas drag on smaller fronds ( < 3 g fresh weight) of the two species was similar. Drag on large C. crispus thalli was greater mainly because they exhibit greater surface area for a given biomass than do large M. stellatus. Dislodgement by hydrodynamic forces has more severe ecological consequences for M. stellatus because regeneration from holdfasts is slower than in C. crispus. A reduced surface area:biomass ratio coupled with greater strength may lessen wave-induced disturbance and be important to maintaining a high abundance of M. stellatus in the low intertidal zone of wave-swept shores.

Stomatal morphology and ontogeny in Spirodela intermedia W. Koch

Stomatal morphology and ontogeny were studied in the epistomatic fronds of Spirodela intermedia W. Koch. Stomata in mature fronds do not form rows, but the orientation of their axis closely follows the veins; stomatal frequency increases gradually from a zone without stomata, near the proximal end, up to the margins all around the frond. Mature stomata are surrounded by between four and nine (generally six to seven) subsidiary cells, forming an irregular ring. They are classified as actinocytic or cyclocytic. Stomatal ontogeny was studied in small fronds, where three zones were delimited from the proximal to the distal end: meristematic, of stomatal initiation and differentiation, and of maturation. The ontogeny of the zone without stomata and of the stomata in the proximal part of the future mature fronds was studied in medium-sized fronds. The positional relationship of developing stomata with respect to the adaxial lobe of a two-lobed membrane covering the proximal part of the frond is established. It was not possible to see unequal divisions in the protodermal cells. Neighbouring cells of the guard-cell mother-cells divide in planes perpendicular and mostly parallel to the outline of the meristemoid. These divisions give rise to perigene subsidiary cells, although one or more of them may possibly be agene cells. The stomatal complex could thus be either euperigenous or hemiperigenous.

Microgonium (Hymenophyllaceae) in Malesia, with Special Reference to Peninsular Malaysia

Summary. The six species of Microgonium occurring in south-east Asia and Malesia are described, illustrated and distinguished and their distributions reviewed. M. tahitense is reported for the first time from Malaya and Thailand and M. mindorense from Java and Borneo. In west Malaysia the latter is much commoner than M. bimarginatum, with which it has been confused hitherto and which is now known from Borneo only by one recent collection. Specimens of M. henzaianum (previously known by a single Burmese collection) from south Vietnam and southern Thailand suggest that it might occur in northern Malaya. Microgonium is one of the more easily recognised and circumscribed of the filmy-fern genera segregated from Trichomanes when the latter is subdivided by taxonomists wishing to recognise more than two (sometimes four) genera in the diverse and complex family Hymenophyllaceae. The genus Microgonium, established by Presl (1843) and maintained by van den Bosch (1861) and Copeland (1938), is characterised by small fronds, with entire, glabrous margins, often simple, sometimes lobed (rarely pinnatifid) apically in an irregular fashion. The veins are dichotomously, not pinnately, branched and in some species are radial in arrangement. All species have false veins (veinlets) between and parallel to the true veins and the two may connect proximally as well as distally at a submarginal false vein, which is possessed by some species. The sorus has a conical or tubular indusium, widening to a flared circular mouth, usually completely immersed in the lamina. Microgonium is closely related to Didymoglossum (whose frond margins have short, stout black-brown hairs) and especially to Crepidomanes, whose species are distinguished by having the lamina pinnatifid or more dissected, true veins pinnately divided and no connection between true and false veins (including the submarginal vein) and in many species the sori are free with bilabiate lips. Crepidomanes species also have chromosome numbers based on n = 36, rather than n = 34 as in Microgonium. There is a very small species of this alliance, T. parvifolium Baker, occurring in peninsular Thailand (and north to southern Burma), which has simple to quadrifurcate fronds and is thus intermediate in dissection between the two genera. It has usually been placed in Microgonium (Copeland 1938, Tagawa & Iwatsuki 1967, 1975) but on the basis of its venation (Iwatsuki 1978) and its possession of a clearly bilabiate and pointed lip to the indusium, it is better placed in Crepidomanes. Microgonium consists of about 19 species, four in the neotropics (Wessels Boer 1962), four in mainland Africa (Pichi Sermolli 1982) and about five in Mad- agascar and the Mascarene and Seychelle Islands (Christensen 1932, Tardieu-

Kinetic studies of growth and flowering of Lemna gibba G3 under continuous light: Effects of night interruptions with red and far-red light

Growth and flowering of individual fronds of Lemna gibba G3 was analysed. Fronds that formed flowers under a standard continuous light condition were divided into three groups: large, middle and small fronds. Diameter of the fronds of each group at the 6.5th day of the continuous light was 1100-340 μm 330-250 μm and <200 μm, respectively. Short-day treatments decreased flower formation in both large and small fronds. Red or far-red light interruption of the dark period of the short-day preceding the continuous light period increased or decreased flowering only in the large fronds. This was taken to indicate that the night interruptions altered starting time of flower induction but not subsequent growth of flower buds. The kinetics of flower and frond production was analysed. It was suggested that the first flower bud was induced during the second day.

Variation in Costa Rican Ophioglossum palmatum and Nomenclature of the Species

In establishing the monotypic genus Cheiroglossa, Presl (1845, p. 57) segregated Ophioglossum palmatum on the following basis: Differt ab Ophioglosso habitu, reticulo venarum simplici, ortu spicarum plurium e margine frondis, ab Ophiodermate fronde revera stipitata, venulis secundariis intra maculas et ad maculas marginales liberis, spicis pluribus ad basim frondis marginalibus. Presl (1845, p. 56) also accepted the epiphytic and monotypic genus Ophioderma (Blume) Endl., which differs from Ophioglossum sensu stricto and from Cheiroglossa in having fronds that are narrow, strap-shaped, and entire or rarely forked at the apex, and in the median, basal position of a single or a pair of fertile segments: Sed Ophioderma ab Ophioglosso revera differt non solum habitu frondis fasciaeformi, sed praesertim venarum maculis simplicibus, venulis liberis nullis, exortu laterali spicae e vena media frondis. In the Index Filicum Christensen recognized neither segregate; Nakai (1925) rejected Cheiroglossa as a genus but upheld Ophioderma; Clausen (1938, p. 111) considered Cheiroglossa and Ophioderma to be subgenera of Ophioglossum; and Copeland (1947, p. 11) also submerged both into that genus, stating that a number of species are intermediate and link the three genera. Although there may be no cytological differences (Ninan, 1958), there are a number of morphological and anatomical reasons for separation at the subgeneric level (Chrysler, 1941; Nishida, 1952; Clausen, 1954, pp. 496-498; Maroti, 1965; van Cotthem, 1973). Several species and varieties have been proposed in subg. Cheiroglossa. Cheiroglossa malgassica (C. Chr.) Pic. Ser., from Madagascar, Reunion, and the Seychelles Islands, differs from typical 0. palmatum in having smaller fronds and areoles, in the fertile segments mostly inserted near the base of the sterile blade, and in a less deeply incised and thicker lamina and uniformly thick veins. Cheiroglossa louisii (Taton) Pic. Ser., from the Congo, has dichotomously segmented fronds with very long, narrow segments, hexagonal, elongate areoles with few included veinlets, and the fertile segments sometimes furcate. Only two collections are known of this species. Cheiroglossa austrobrasiliensis Brade, from Brazil, differs in lamina dimensions and color of the sterile segment and common petiole. It has narrow areoles, and the fertile segments are inserted both on the petiole and on the margins of the sterile segment. The present study is based on six large clumps of 0. palmatum collected at San Rafael de Vara Blanca, Province of Heredia, at 2000 m altitude. The plants grew as epiphytes on various trees, mostly Quercus sp. and Magnolia poasana Standl., together with other epiphytes, including Orchidaceae, Bromeliaceae, Araceae, and bryophytes. The area is a montane cloud forest, with rainfall averaging 3000 mm/year and temperatures 18?C. Voucher specimens are: Wagner & Gomez 1181 (CR), Lent 1615 (F), and Gomez 5070 (CR), and totalled 57 fertile fronds.