Noris Salazar Allen

Altitudinal changes in temperature responses of net photosynthesis and dark respiration in tropical bryophytes

BACKGROUND AND AIMS There is a conspicuous increase of poikilohydric organisms (mosses, liverworts and macrolichens) with altitude in the tropics. This study addresses the hypothesis that the lack of bryophytes in the lowlands is due to high-temperature effects on the carbon balance. In particular, it is tested experimentally whether temperature responses of CO(2)-exchange rates would lead to higher respiratory carbon losses at night, relative to potential daily gains, in lowland compared with lower montane forests. METHODS Gas-exchange measurements were used to determine water-, light-, CO(2)- and temperature-response curves of net photosynthesis and dark respiration of 18 tropical bryophyte species from three altitudes (sea level, 500 m and 1200 m) in Panama. KEY RESULTS Optimum temperatures of net photosynthesis were closely related to mean temperatures in the habitats in which the species grew at the different altitudes. The ratio of dark respiration to net photosynthesis at mean ambient night and day temperatures did not, as expected, decrease with altitude. Water-, light- and CO(2)-responses varied between species but not systematically with altitude. CONCLUSIONS Drivers other than temperature-dependent metabolic rates must be more important in explaining the altitudinal gradient in bryophyte abundance. This does not discard near-zero carbon balances as a major problem for lowland species, but the main effect of temperature probably lies in increasing evaporation rates, thus restricting the time available for photosynthetic carbon gain, rather than in increasing nightly respiration rates. Since optimum temperatures for photosynthesis were so fine tuned to habitat temperatures we analysed published temperature responses of bryophyte species worldwide and found the same pattern on the large scale as we found along the tropical mountain slope we studied.

Molecular and morphological evidence for distinct species in Dumortiera (Dumortieraceae)

Abstract Contemporary taxonomists usually recognize a single species in Dumortiera, which is widely distributed through tropical and subtropical regions and extends into some temperate regions. Two subspecies, D. hirsuta subsp hirsuta and subsp. nepalensis, may be recognized, and both of these were thought to occur in Central America. We sequenced four loci, the nuclear internal transcribed spacer region ITS, and three chloroplast loci (rbcL, psbA-trnH and rpoC1) from 50 samples of Dumortiera across its geographic range to test for phylogenetic structure within the species and its congruence to morphological and geographic patterns. We also used light and scanning electron microscopy to examine morphological differences between accessions from Central America. Phylogenetic inferences reveal two highly distinct lineages: the first apparently restricted to Central America, and the second distributed across all the geographic regions sampled. This widespread lineage could itself be subdivided into several genetically and geographically distinct clades. The restricted Central American lineage contains plants that have a light green velvety appearance, due to an abundance of papillae on their upper thallus surface. These can therefore be distinguished morphologically from sympatric accessions of the widespread lineage, which are dark green, with a wide range of papillae densities (absent, few or abundant) on the thallus and usually with abundant marginal hairs. However, the wider application of these characters to lineages outside the Central American region has not yet been confirmed. We conclude that Dumortiera contains at least two, if not more, distinct species. The Asian epithet nepalensis does not seem applicable to plants in Central America, as the papillate morphotypes to which this name has been applied form an exclusively new world lineage. A thorough morphological revision of the genus, and reinvestigation of type material, is required.

Cyathodium foetidissimum (Marchantiales), An Asiatic Species New to Tropical America

Abstract Cyathodium foetidissimum Schiffn., an Asiatic species is reported for the first time for the Neotropics. The species is distinguished by the presence of a central multistratose area of cells; oil cells with a single oil body; strongly dimorphic rhizoids; large ventral scales; monoicous condition with an apical, male receptacle flanked by archegonia in undulate laminar involucres; an operculum of 12 cells; upper cells of the capsule with bar-like thickenings; elaters with three bands; and verrucose spores. The closest relative in habit is Cyathodium spruceanum Prosk., but plants of this species lack a “midrib” and have oil bodies and chloroplasts in the thallus cells; it is dioicous and the spores are lamellate-reticulate. Mature male plants of Cyathodium foetidissimum have been found along with bisexual thalli. This is the first report of both types of gametophytes occurring simultaneously in monoicous species of neotropical Cyathodium.

Occurrence of (-)-Geosm in and Other Terpenoids in an Axenic Culture of the Liverwort Symphyogyna brongniartii

An axenic culture of Symphyogyna brongniartii has been initiated from spores on modified Benecke medium. Growth was best on Gam borg B5 medium with 0.3% sucrose, with a doubling time of 36 days. The culture produced the same terpenoids as plants growing in their natural habitat, perrottetianal A being the major constituent. Also found were bicyclogermacrene, β-barbatene, δ-selinene, β-cubebene, spathulenol, and (-)-geosm in . The latter compound was hitherto only known from microorganisms. Synthesis rate of terpenoids during the passage period and quantitative differences in terpenoid production on different mineral media were investigated.

Nothoceros superbus (Dendrocerotaceae), a new hornwort from Costa Rica

Abstract A new Neotropical species of hornwort, Nothoceros superbus, is described from Costa Rica. The species is distinguished by its large size, strongly costate thallus with crispate-imperforate wings, dioicous condition and green, unicellular spores that are minutely papillose with tubercules dispersed on the borders and the distal face, and sometimes clustered in the center of the distal face. Nothoceros superbus has a combination of Megaceros-like spores and a Dendroceros-like thallus growth-form. The combination of these features supports its placement in the genus Nothoceros in the Dendrocerotaceae. Nomenclatural clarifications on Nothoceros endiviaefolius (Mont.) J. Haseg. and Nothoceros giganteus (Lehm. & Lindenb.) J. Haseg. are made. Based on new molecular and morphological data a new combination, Nothoceros canaliculatus (Pagán) comb. nov., is proposed.

Cyathodium bischlerianum, sp. nov. (Marchantiales) a New Species from the Neotropics

Abstract Cyathodium bischlerianum is described as a new Neotropical species from Panama. The species is distinguished by its slender, delicate thallus; a prominent dorsal pore at base of involucre; monoicous condition with 1–2 archegonia per involucre, and male receptacles on sides of thallus; sporophytes without operculum; cells of upper third of capsule with bar-like thickenings; elaters attached to base of capsule wall with 3–4 bands; and spinose-bulbose spores. This species resembles the Asiatic C. aureonitens in spore ornamentation, but its monoicous condition, lack of operculum, naked involucre, and ornamentation of upper capsule cells separate it from its Asiatic relative. It is also related in morphology, sexual condition, and spore ornamentation to C. cavernarum.

The Life-Form and Presence of Epigametophytic Plants in the Genus Leucophanes

Leucophanes is a genus of mainly palaeotropical turf forming mosses. Populations consist of acrocarpous, branched or unbranched gametophores. In the latter, the turfs are formed by layers of individual plants each attached by rhizoids to the plant beneath it. These fully grown epigametophytic plants are of the same gender as the supporting plant. It is suggested that this particular growth habit is an adaptation to continue turf existence by the development of various strategies of vegetative reproduction, e.g., germination of leaf tip gemmae and readily detachable short branching systems. This is of importance in species for which sexual reproduction has not been demonstrated and which have few or no subterminal innovations. Growth habit and structural features displayed by the gametophytes of Leucophanes are also adaptations for water retention. It is most likely that the life-form characteristic of this genus developed in relation to environmental stresses imposed by the corticolous habit in seasonally dry tropical forests. The genus Leucophanes, with 41 valid names, is widely distributed in tropical and subtropical areas of the Old World (Wijk et al. 1964; Gangulee 1971). Three species have been reported for the Neotropics (Wijk et al. 1964). The genus is composed of acrocarpous, cortico- lous mosses, characterized by the structure of the leaf, analogous to that of Leucobryum, with a central layer of chlorophyllous cells surrounded on each surface, by one or more layers of porose hyalocysts (Fig. 1-3). A single costa runs the length of the leaf. About 90% of the species develop gemmae (Fig. 4, 5) and all produce rhizoids at the apex of the leaves. The plants grow in turfs of variable sizes on rotten logs, and the trunks, branches and bases of trees. Most species are dioicous with male and female plants structurally similar. One species, L. serra- tulum Fleisch., is synoicous. In some species, L. calymperatum C. Mill., L. brasiliense Broth., L. rodriguezii C. Mill. and L. unguiculatum Mitt. only female plants are known.

Syrrhopodon simmondsii New to Panama and Central America

Syrrhopodon simmondsii Steere is reported new to Panama and Central America on a specimen collected on Barro Colorado Island, Panama. During a recent trip related to the survey of the hepatics of Barro Colorado Island, I (with S. R. Gradstein) collected a sample of a limbate Syrrho- podon on protruding roots of a tree on Balboa Trail, 500-600 m (stakes 5-6) from the beginning of the trail (SalazarA. & Gradstein 15126, PMA). Two lim- bate species of Syrrhopodon have been previously reported for the Island (Salazar Allen et al. 1991): S. gaudichaudii Mont. and S. parasiticus (Brid.) Besch. Nevertheless, the specimen found was very different from these species in that the leaves bore prominent short marginal cilia at the shoulders, the plants were very small (perhaps one reason why it has been overlooked in previous surveys) growing in dispersed turfs, and rhizoids were purple-red. A close examination of the plants under the micro- scope and comparisons with herbarium duplicates of limbate species of Syrrhopodon from Central and South America indicated that the specimen was S. simmondsii Steere, described by Reese (1993) as an endemic species of northern South America. The plants were growing intermixed with the moss Oc- toblepharum albidum Hedw. and the leafy liverwort Pictolejeunea picta (Gott. ex Steph.) Grolle. With this new report, the geographical range of the species is amplified to include Panama. It is most probable that it also occurs in other areas of Central America. In relation to habitat, Reese (1987) has indicated that the majority of Syrrhopodon species appear to be plants of warm, humid lowlands. The localities from which S. simmondsii have been previously reported and the one at Barro Colorado Island fit well with this habitat definition. Other bryophytes that grow in similar habitats are, e.g., the leafy liv- erworts Radula macrostachya Lindenb. & Gott., Pictolejeunea picta, and the mosses Calymperes ero- sum C. Miill., C. palisotii Schwaegr., Octoblephar- um albidum, Pilosium chlorophyllum (Hornsch.) C. Miill., and Taxithelium planum (Brid.) Mitt.

Bryum incrassatolimbatum New to Panama, with First Description of Its Sporophyte

Bryum incrassatolimbatum Card. is reported new to Panama and its sporophytes are described and illustrated for the first time. This moss appears to be most closely allied to B. cellulare Hook., based on the morphology of the capsule. Since the original description by Cardot (1909), based on sterile material from Mexico, the taxo- nomic status of Bryum incrassatolimbatum has been uncertain (Ochi 1980; Shaw 1981). Its distributional range has been extended to Oklahoma and Arizona in the United States (Shaw 1981). Plants of this species with sporophytes are here reported for the first time from Panama and a description of the sporophyte is provided (Fig. 1-6).

A Preliminary Report of Rhizoidal Heads in Leucobryum martianum

Development of rhizoidal heads in Leucobryum martianumfrom Cerro Jefe, Panama, is reported for the first time. Leucobryum martianum (Hornsch.) Hampe is a moss species distributed throughout tropical Amer- ica. It grows in forests of low to high altitudes. In Panama, it occurs from sea level to elevations of over 1,000 m. The plants, 2-3 cm in height, grow in dense to loose turfs; the leaves are erect-crowded and falcate to falcate-secund. Like many other species of Leucobryum (Crum & Anderson 1981; Crum & Steere 1957), the leaves can serve as asexual dia- spores. Crum (1976) and Crum and Anderson (1981) have reported growth of rhizoids at the tips of leaves of Leucobryum glaucum (Hedw.) Angstr., suggesting that this character may be indicative of high poten- tialities for establishment of new plants from leaf fragments after dispersal. Production of rhizoids from leaves is of common occurrence in various