Secondary Pit Connections Research Articles

Evidence for the proposal that Palisada corallopsis and P. furcata (Ceramiales, Rhodophyta) are conspecific

Abstract Palisada corallopsis has a widely reported distribution in the western and eastern Atlantic and some areas of the Indo-Pacific Ocean, whereas P. furcata has a more restricted distribution, reported only from Brazil and Cuba. Palisada corallopsis and P. furcata were collected from their type localities, Havana, Cuba and Ceará, Brazil, respectively, and compared by morphological and molecular analyses using rbcL and COI-5P genes. The molecular results placed the sequences from the type locality of both species in the same clade, showing low genetic divergence, 0.95 % for rbcL and 1.6 % for COI-5P. Morphologically, the species share similar habits, with branchlets bi-to trifurcated, cortical cells that may be arranged as a palisade and connected by secondary pit-connections. Our detailed morphological observations, including examination of the type specimens, and molecular analyses demonstrate that P. corallopsis and P. furcata are conspecific, P. furcata being a later taxonomic synonym of P. corallopsis.

Laurencia mediterranea sp. nov. (Ceramiales, Rhodophyta) from the central Mediterranean Sea

Abstract The identification of macroalgal species within the Laurencia complex is challenging, due to the presence of inconspicuous morphological characters, extensive variation in these traits and a diverse biogeography. Moreover, for a number of these species, no DNA sequence data are available in online databases. For this study, five algal specimens, tentatively assigned to Laurencia, were collected from Malta in the central Mediterranean Sea and studied using an integrative systematics approach. An analysis of the data resulted in the description of a new species, Laurencia mediterranea using combined morphological and molecular criteria, including COI-5P and rbcL. Morphologically L. mediterranea sp. nov. was distinct from other Laurencia spp. in the type of holdfast, the colour and shape of the thallus, the presence of secondary pit connections, lenticular thickenings and ‘corps en cerise’. Moreover, a new genetic species cluster indicated a separate taxon at the species level. Our study demonstrates that genetic sequences having clear links to sample metadata and digital herbaria are indispensable for macroalgal biodiversity research. This approach could offer a solution for algal taxonomy in cases where biogeography is important and limited sequence data exist in online DNA libraries.

A new red algal crust from New Zealand: Apophlaea darchinoae sp. nov. (Hildenbrandiales)

ABSTRACT New Zealand’s algal flora is still far from fully explored, and new taxa continue to be discovered. The taxonomy of the red algal order Hildenbrandiales, consisting mostly of crustose members, is controversial as descriptions are largely based on limited morphological features. The order Hildenbrandiales is also in a close, apparently obligate, relationship with an endophytic fungus. Apophlaea is a genus in this order currently comprising two described species, both endemic to New Zealand. The morphology of this genus is more complex than that of other members of the Hildenbrandiales as it consists of extensive upright thalli. Sampling of Apophlaea in New Zealand, especially in the southern part of the North Island, has led to the discovery of a genetically distinct entity, that is only crustose. We propose a new species for this entity, Apophlaea darchinoae sp. nov., which is found on rocks in the high intertidal zone. This species has the typical tetrasporangial conceptacles of Apophlaea and no other reproductive structures were observed, and it consists of filaments that are laterally joined by secondary pit connections. Apophlaea darchinoae can be found in sympatry with A. sinclairii in the north of the North Island. We provide molecular evidence for the distinct nature of A. darchinoae and provide observations of extensive fungal filaments within this new species.

Based on morphology and molecular data, Palisada rigida comb. nov. and Laurencia decussata comb. et stat. nov. (Rhodophyta, Rhodomelaceae) are proposed

Inspecting herbaria collections of Laurencia rigida highlighted frequent misidentifications between L. rigida and L.heteroclada f. decussata, two poorly studied taxa from Australia. Recent collections of DNA material, including from topotypematerial, allowed for re-examination of these two taxa using molecular techniques. Detailed morphological andmolecular analyses based on two markers (rbcL and COI-5P) strongly supported these two taxa as being distinct fromeach other and requiring nomenclatural changes. Comprehensive morphological analyses highlighted features useful foraccurate identifications. Interestingly, L. rigida was found to belong to the genus Palisada with evidence from both themorphology and molecular data. Therefore, this study proposed recognizing L. rigida as Palisada rigida comb. nov. Moleculardata for L. heteroclada f. decussata on the other hand supported its separation from L. heteroclada, with too greata molecular distance to be considered a variety. Morphological characters that best separated P. rigida from L. decussataincluded seven characters; number of pericentral cells per vegetative axial segment, the presence of secondary pit connections,the presence of lenticular thickenings, tetrasporangia alignment, the presence of corps en cerise, holdfast morphology,and overall plant shape. Morphologically, L. heteroclada f. decussata was also separated from L. heteroclada,particularly by the following characteristics; ultimate branchlets morphologies, lower order branch lengths, primary axisand holdfast morphologies. Therefore, it was proposed that L. heteroclada f. decussata is recognized at a species level asL. decussata comb. et stat. nov.

The habitat-modifying red alga Ramicrusta on Pacific reefs: A new generic record for the Tropical Northwestern Pacific and the description of four new species from Guam.

The genus Ramicrusta (order Peyssonneliales) is a new record for Micronesia, with range expansions of Ramicrusta fujiiana and R. lateralis to Guam. In addition, four species (Ramicrusta adjoulanensis, R. asanitensis, R. labtasiensis, and R. taogamensis) are newly described from Guam using molecular and anatomical characters. Ramicrusta lateralis specimens from Guam share most anatomical features with the holotype description from Vanuatu, but the plants from Guam are more tightly adherent, rigid, and robust than those of Vanuatu. Ramicrusta adjoulanensis possesses a well-developed epithallus with frequent cell fusions, secondary pit connections, and lacking hair bases or trichocytes, similar to Ramicrusta bonairensis. Ramicrusta adjoulanensis differs from other Ramicrusta species in having occasionally free margins and being attached by frequently produced, relatively long rhizoids (75–100 μm long). Ramicrusta asanitensis shares features with many other species, but the thickness of the crust (upwards of 2 mm thick), heavy calcification in the epithallus, and the extent of secondary, tertiary, and quaternary growth, differentiate it from other Ramicrusta species. Ramicrusta labtasiensis shares features with its close relative Ramicrusta lateralis but possesses frequent, robust, and relatively long rhizoids (75–95 μm long) throughout its entire undersurface. Ramicrusta taogamensis resembles its close relative Ramicrusta appressa but is primarily distinguished by its generally well-developed epithallus with occasional secondary pit connections and cell fusions. The six species reported here make Guam equal to Vanuatu in currently having the highest known species richness of Ramicrusta in the world.

Formation of secondary pit connections by conjunctor cells in a coralline red alga

ABSTRACT For more than eighty years, the accepted view of the origin of secondary pit connections in coralline red algae has been that a narrow channel of direct fusion forms between adjacent intercalary meristematic cells and a pit plug is subsequently deposited within the fusion channel; no cell or nuclear division is involved. Such a mechanism contrasts with the prevailing pattern of secondary pit connection formation among red algae in which a highly unequal, intercalary cell division produces a short-lived diminutive cell, the conjunctor cell, that fuses with an adjacent cell; the pit connection produced in the formation of the conjunctor cell is then shared by the two surviving cells. Study of Lithophyllum impressum by light and transmission electron microscopy revealed that asymmetrical lateral divisions of meristematic cells, as well as cells throughout the perithallus, produce tiny nucleated conjunctor cells. Thus, these findings indicate that secondary pit connection formation in this coralline alga does not occur by a direct mechanism nor are these connections generated only in the layer of intercalary meristematic cells as long believed.

Detail description of Lithophyllum okamurae (Lithophylloideae, Corallinales), a widely distributed crustose coralline alga in marine ecosystems

Lithophyllum okamurae is one of the important encrusting coralline algae, which plays important roles as primary producer, carbonate sediment builder, and habitat provider in the marine ecosystems. In this study, L. okamurae was collected from tropical coast of Sanya, and firstly described based on both detailed morph-anatomical characteristics and molecular studies of typic DNA sequences. The structure of the thalli of L. okamurae was pseudoparenchymatous construction with radially organized dimerous organizations in the crustose portion. The pseudoparenchymatous construction were composed of three parts, including 1 to 3 layers of epithelia cells which had flatten to round outermost walls, one layer of square or rectangular cells of the hypothallia and multiple layers of square or elongated rectangular peripheral cells. Palisade cells were observed, and the cells of the contiguous vegetative filaments were connected by secondary pit-connections with cell fusions absent. The carposporangial conceptacles, the spermatangial conceptacles, the bisporangial conceptacles and the tetrasporangial conceptacles were observed, and all these four kinds of conceptacles were uniporate. The spermatangial conceptacles were slightly convex and buried at shallow depths in the thalli tissues, and the carposporangial conceptacles and asexual conceptacles were protruding and conical. Phylogenetic studies based on DNA barcoding markers of 18S rDNA, COI, rbcL and psbA revealed that L. okamurae clustered with the closest relation of L. atlanticum, and formed a distinct branch. Based on the comparative anatomical features and the molecular data, the detailed description of the valid species of L. okamurae was firstly given in this study to provide theoretical basis for algae resources utilization and conservation in marine ecosystems.

Molecular and morphological reappraisal of Spyridiocolax capixabus (Spyridiaceae, Rhodophyta), a rare endemic parasite from Brazil

Abstract The monotypic red algal parasite genus Spyridiocolax was proposed from material from the coast of Espírito Santo to accommodate Spyridiocolax capixabus, endemic from Brazil. The species is rare, and we performed a morphological reappraisal and the first molecular characterization of S. capixabus. Parasite specimens growing on Spyridia clavata were collected in the type locality, Itaoca Beach, Espírito Santo. Spyridiocolax capixabus forms colorless warts on the branches of S. clavata, and the secondary pit connections were described for the first time. Male, female and tetrasporophytic structures were observed growing in the same host plant. The plastid rbcL sequences of parasite and host were identical. A divergence of one nucleotide was found to the nuclear SSU rRNA gene, suggesting that the parasite retains the chloroplast of its host. Both plastidial and nuclear phylogenies supported the close relationship of S. capixabus and S. clavata. The data obtained corroborate other studies with rhodophycean parasites, which show morphological and molecular similarities between parasites and hosts. To maintain the monophyly of the host genus, the transfer of S. capixabus to Spyridia is proposed here on the basis of morphological and molecular evidence. Our study constitutes a starting point for reinvestigating the red algal parasites in Brazil.

Development of the red algal parasite Vertebrata aterrimophila sp. nov. (Rhodomelaceae, Ceramiales) from New Zealand

ABSTRACTParasitic red algae grow only on other red algae and have over 120 described species. Developmental studies in red algal parasites are few, although they have shown that secondary pit connections formed between parasite and host and proposed that this was an important process in successful parasitism. Furthermore, it was recorded that the transfer of parasite nuclei by these secondary pit connections led to different host cell effects. We used developmental studies to reconstruct early stages and any host cell effects of a parasite on Vertebrata aterrima. A mitochondrial marker (cox1) and morphological observations (light and fluorescence microscopy) were used to describe this new red algal parasite as Vertebrata aterrimophila sp. nov. Early developmental stages show that a parasite spore connects via secondary pit connections with a pericentral host cell after cuticle penetration. Developmental observations revealed a unique connection cell that grows into a ‘trunk-like’ structure. Host cell transformation after infection by the parasite included apparent increases in both carbohydrate concentrations and nuclear size, as well as structural changes. Analyses of molecular phylogenies and reproductive structures indicated that the closest relative of V. aterrimophila is its host, V. aterrima. Our study shows a novel developmental parasite stage (‘trunk-like’ cell) and highlights the need for further developmental studies to investigate the range of developmental patterns and host effects in parasitic red algae.

Morphology and distribution of Laurencia sp.1 (Ceramiales, Rhodophyta) from Myanmar

The plants of Laurencia sp. 1 were collected from Nyaw Byin (Lat. 13˚40′N, Long. 98˚00′E) to Sittwe (Lat. 20˚08′ N, Long. 92˚54′E) of Myanmar from 1987 to 2019. Laurencia sp.1 was characterized by the absence of corps en cerise within each superficial cortical cell, and lenticular thickenings in the walls of medullary cells, and the presence of secondary pit-connections between cortical cells, four pericentral cells per axial segment and tetrasporangia formed in the apical portion of the lateral axis with a parallel arrangement and cystocarps with one or more ostioles, based on the external and internal morphologies of both the vegetative and reproductive structures. The distribution and some ecological notes along with potential uses of this species were briefly described.

Comparative studies of photosynthetic capacity in three pigmented red algal parasites: Chlorophyll a concentrations and PAM fluorometry measurements

SUMMARYOver 100 species of red algae have been described as parasites on other red algae, but the majority show some degree of pigmentation. This raises the question of their parasitic status, especially their abilities to photosynthesize and their dependence on their host for fixed carbon. Are they considered parasites only based on morphological characters, for example, reduced size and secondary pit connection to the host? Translocation of nutrients from host to parasite have been shown for very few red algal parasites, and these were mostly unpigmented. This study investigated three pigmented red algal parasites (Rhodophyllis parasitica, Vertebrata aterrimophila and Pterocladiophila hemisphaerica) from New Zealand. We quantified their chlorophyll a content and also measured their PSII capacity using PAM fluorometry. All three parasites contained chlorophyll a. The parasites Rhodophyllis parasitica and Vertebrata aterrimophila were not able to photosynthesize and must therefore be fully nutritional dependent on their host. The parasite Pterocladiophila hemisphaerica was able to photosynthesize independently, but based on molecular characteristics we suggest that it relies on the host plastid to do photosynthesis. Our results support the parasitic status of all three species and highlights the necessity of more studies investigating the differences in host dependency in red algal parasites.

JOHNSON & KASKA 1965 FOSSIL CORALLINE ALGAE FROM GUATEMALA (REVISION OF THE JESSE HARLAN JOHNSON COLLECTION, PART 4)

The original collections of eight species described by Johnson & Kaska (1965) from several Guatemalan localities and ages, have been examined, re-documented and critically revised. The generic placement of Aethesolithon guatemalaensum , Lithothamnium? primitiva, Lithothamnium diagramaticum , Lithothamnium guatemalense , Lithothamnium toltecensum, and Jania occidentalis resulted incorrect under modern taxonomic criteria, and changed accordingly, while a lectotype specimen was selected for Amphiroa guatemalense and Amphiroa kaskaella. We place tentatively L. diagramaticum in the new combination Sporolithon? diagramaticum on the base of the occurrence of secondary pit-connections and vegetative and reproductive anatomy corresponding to some extant species of the genus Sporolithon . L. toltecensum was based on few Miocene sterile thalli occurring with some fertile specimens of the same age - the latter incorrectly identified under the name L. florea brassica (Millet) Lemoine - both corresponding to the extant, long-lasting species Lithothamnion crispatum Hauck. The occurrence of large cell fusions and trichocytes, the shape and structure of the uniporate conceptacles and the dimerous construction collectively indicate that Aethesolithon guatemalaensum belongs to the genus Hydrolithon, with the new combination H. guatemalaensum (Johnson & Kaska) Basso & Granier. The vegetative anatomy of Jania occidentalis corresponds to that of a co-occurring Corallina, already identified as C. matansa Johnson . Lithothamnium? primitiva is not a coralline alga, since it is conspecific with Marinella lugeoni Pfender. The vegetative features of the sterile “ Lithothamnium guatemalense ” exclude it from the genus Lithothamnion , but the absence of important diagnostic characters suggests leaving it incertae sedis under the original binomial.

Molecular phylogenies support taxonomic revision of three species of Laurencia (Rhodomelaceae, Rhodophyta), with the description of a new genus

The systematics of the Laurencia complex was investigated using a taxon-rich data set including the chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene only and a character-rich data set combining mitochondrial cytochrome oxidase 1 (COI-5P), the rbcL marker, and the nuclear large subunit of the ribosomal operon (LSU). Bayesian and ML analyses of these data sets showed that three species hitherto placed in the genus Laurencia J.V.Lamour. were not closely related to Laurencia s. str. Laurencia caspica Zinova & Zaberzhinskaya was the sister group of the remaining Osmundea Stackh. species, L. crustiformans McDermid joined Palisada and L. flexilis Setch. consisted of an independent lineage. In light of these results a new genus, Ohelopapa F.Rousseau, Martin-Lescanne, Payri & L.Le Gall gen. nov., is proposed to accommodate L. flexilis. This new genus is morphologically characterized by four pericentral cells in each vegetative axial segment; however, it lacks ‘corps en cerise’ in cortical cells and secondary pit connections between cortical cells, which are characteristic of Laurencia. Three novel combinations are proposed to render the classification closer to a natural system: Ohelopapa flexilis (Setch.) F.Rousseau, Martin-Lescanne, Payri & L.Le Gall comb. nov., Osmundea caspica (Zinova & Zaberzhinskaya) Maggs & L.M.McIvor comb. nov. and Palisada crustiformans (McDermid) A.R.Sherwood, A.Kurihara & K.W.Nam comb. nov.

Crusticorallina gen. nov., a nongeniculate genus in the subfamily Corallinoideae (Corallinales, Rhodophyta).

Molecular phylogenetic analyses of 18S rDNA (SSU) gene sequences confirm the placement of Crusticorallina gen. nov. in Corallinoideae, the first nongeniculate genus in an otherwise geniculate subfamily. Crusticorallina is distinguished from all other coralline genera by the following suite of morpho-anatomical characters: (i) sunken, uniporate gametangial and bi/tetrasporangial conceptacles, (ii) cells linked by cell fusions, not secondary pit connections, (iii) an epithallus of 1 or 2 cell layers, (iv) a hypothallus that occupies 50% or more of the total thallus thickness, (v) elongate meristematic cells, and (vi) trichocytes absent. Four species are recognized based on rbcL, psbA and COI-5P sequences, C.painei sp. nov., the generitype, C.adhaerens sp. nov., C.nootkana sp. nov. and C.muricata comb. nov., previously known as Pseudolithophyllum muricatum. Type material of Lithophyllum muricatum, basionym of C.muricata, in TRH comprises at least two taxa, and therefore we accept the previously designated lectotype specimen in UC that we sequenced to confirm its identity. Crusticorallina species are very difficult to distinguish using morpho-anatomical and/or habitat characters, although at specific sites, some species may be distinguished by a combination of morpho-anatomy, habitat and biogeography. The Northeast Pacific now boasts six coralline endemic genera, far more than any other region of the world.

Morphological and molecular characterization of Hydrolithon rupestre (Corallinaceae, Corallinales, Rhodophyta): first report from the Mediterranean Sea

The genera Hydrolithon and Porolithon are the most discussed taxa of non-geniculate Corallinaceae, as well as the most poorly known. Anatomical observations based usually on thallus construction, number of epithallial cell layers, trichocyte arrangement, occurrence of vegetative filaments between the trichocytes, and presence/absence of cell fusions and secondary pit connections led to different interpretations mainly due to the lack of available reproductive material from type specimens. Recently molecular surveys on the phylogeny of the Corallinales supported the hypothesis of considering Hydrolithon and Porolithon as two distinct genera but, up to now, several taxonomic questions remain in part unanswered. For these reasons identification of species belonging to these genera is still very difficult and can often lead to misidentification of taxa. In this study we report the discovery of a species of the Hydrolithon group found along the coast of Vis Island, Croatia, Adriatic Sea. Samples were identified through morpho-anatomical examinations and the phylogenetic position of this species was investigated through molecular analyses based on the nuclear nSSU and the plastidial psbA markers. This finding represents the first report for the Mediterranean Sea of Hydrolithon rupestre, one of the few encrusting coralline algae reported to overgrow live corals. The species can represent a possible threat to populations of Adriatic scleractinian corals.

Sporolithon molle(Heydrich) Heydrich (Sporolithales, Corallinophycidae, Rhodophyta): An Addition to the Atlantic Flora Found on a Remote Oceanic Island

Sporolithon molle (Heydrich) Heydrich has previously only been reported from the Red Sea, Arabian Gulf, Indonesia, and eastern Australia. The species is reported for the first time from the Atlantic Ocean where it was found in the remote oceanic island of Trindade, Brazil. This study provides a comparative account of tetrasporic plants from the Atlantic Ocean against those from the other known locations and from other well-described species of the genus Sporolithon. The specimens reported here, presented all the features of the genus, namely: flared epithallial cells, cells of adjacent filaments joined by both cell fusions and secondary pit connections, cruciately divided tetrasporangia formed within sori; and tetrasporangia bearing apical pore plugs and formed on a single stalk cell. Sporolithon molle differs from other species of Sporolithon mainly by the absence of a layer of elongate cells at the base of tetrasporangial sori. Samples from Trindade differ slightly from the type collection and from specimens from other known locations by the tetrasporangial sori which can be flush to slightly raised (to 3 cells) above the surrounding vegetative thallus surface as opposed to being flush only in all material reported previously.

DNA barcoding and phylogenetics of Ramicrusta and Incendia gen. nov., two early diverging lineages of the Peyssonneliaceae (Rhodophyta)

Dixon K.R. and Saunders G.W. 2013. DNA barcoding and phylogenetics of Ramicrusta and Incendia gen. nov., two early diverging lineages of the Peyssonneliaceae (Rhodophyta). Phycologia 52: 82–108. DOI: 10.2216/12–62.1Secondary pit-connections were previously known from only two species in a single genus of the Peyssonneliaceae, Ramicrusta nanhaiensis and Ramicrusta textilis. However, during ongoing surveys for representative Peyssonneliaceae in Australia and Vanuatu, we uncovered a diversity of peyssonnelioid collections that displayed this anatomical feature. We combined DNA barcoding, using the COI-5P mitochondrial marker to recognize genetic species groups and assign replicate samples to those same groups, with traditional anatomical observations to characterize 11 distinct species with secondary pit-connections. A diverse sampling of the genetic groups was included in molecular phylogenetic analyses using rbcL, EF2 and COI-5P individually and in various combinations to resolve the evolutionary affinities of these species among other Peyssonneliaceae. Our results indicated that peyssonnelioid species with secondary pit-connections resolved in two distinct lineages, necessitating description of Incendia gen. nov. for six new species from Vanuatu – Incendia crenata sp. nov., Incendia regularis sp. nov., Incendia cryptotricha sp. nov., Incendia glabra sp. nov., Incendia basilii sp. nov. and Incendia undulata sp. nov. We additionally expand Ramicrusta, recognizing five species from Vanuatu, Ramicrusta textilis, Ramicrusta lateralis sp. nov., Ramicrusta appressa sp. nov., Ramicrusta trichaurea sp. nov. and Ramicrusta aranea sp. nov., one from southern Australia, Ramicrusta australica sp. nov. and one from New Guinea, Ramicrusta calcea comb. nov.

Developmental morphology and systematics of Trematocarpus dichotomus (Sarcodiaceae, Rhodophyta) from Chile

Rodríguez-Prieto C. and Hommersand M.H. 2012. Developmental morphology and systematics of Trematocarpus dichotomus (Sarcodiaceae, Rhodophyta) from Chile. Phycologia 51: 586–595. DOI: 10.2216/11-122.1Trematocarpus dichotomus, the generitype of Trematocarpus Kützing, was restricted to the Pacific coast of South America from southern Peru to Chiloé in south-central Chile. Our investigation established that the vegetative thallus consists of an outer and inner cortex that encircles a medulla of uniformly separated, cylindrical to compressed filaments cross-linked by secondary pit connections. Spermatia were initially cleaved singly and released from the tip of an elongated spermatangium and later sequentially from a series of developing spermatia that matured basipetally within the spermatangium. Carpogonial branches were three-celled, initially directed outwardly but then curving sharply inwardly, the carpogonium producing an abruptly reflexed trichogyne. A single transverse division of the carpogonium after fertilization resulted in a proximal cell that fused with the first cell of the carpogonial branch, which became the generative auxiliary cell. The auxiliary cell cut off a single gonimoblast initial towards the thallus surface that branched beginning at the three-celled stage, with the cells in adjacent branches linking laterally by secondary pit connections. Surface cortical cells grew and branched to form a pericarp that split into inner and outer pericarp layers separated by a central cavity. Gonimoblast filaments were initially surrounded by inner pericarp from which they grew into the cavity and bore carposporangia terminally in branched chains. The gonimoblast filaments fused lengthwise progressively as they grew, and adjacent filaments linked laterally by secondary pit connections to form a fusion network referred to as the ‘gonimoblast reticulum’. Inner cells of the gonimoblast reticulum fused with cells of the inner pericarp, uniting the carposporophyte with the gametophyte through a basal placenta. Carposporangia may germinate in situ inside the cystocarp. Tetrasporangia were formed successively in nemathecia from elongated tetrasporangial initials on the concave sides of branches and were zonately divided. Several developmental stages documented here are newly reported for Trematocarpus and the family Sarcodiaceae.

First Record ofSporolithon ptychoidesHeydrich (Sporolithales, Corallinophycidae, Rhodophyta) from Thailand

Sporolithon ptychoides Heydrich (Sporolithaceae, Sporolithales), the type species of the genus Sporolithon, is newly reported for Thai waters based on specimens collected from the Gulf of Thailand and the Andaman Sea. A detailed morphological and anatomical account is provided, including comparisons with published data of S. ptychoides and its related species. Epithallial cells are flared. Cells of adjacent filaments connect laterally mostly by secondary pit connections. Tetrasporangia are grouped in sori that occur in patches over the thallus surface. Sori are buried in distinct rows in the thallus. Details of male, female and carposporangial conceptacles of S. ptychoides are described for the first time. Gametangial thalli are monoecious with spermatangia and carposporangia born in uniporate conceptacles. Dendroid spermatangial branches occur on the floor, walls and roof of the male conceptacle chamber. Carpogonial branch consists of a hypogenous cell and a carpogonium. Central fusion cell is absent on the floor of the carposporangial conceptacle chamber.

Hymenenopsis heterophylla gen. et sp. nov. (Delesseriaceae, Rhodophyta) from New Zealand, based on a red alga previously known as Hymenena palmata f. marginata sensu Kylin, with emphasis on its cystocarp development

Lin S.-M., Nelson W.A. and Hommersand M.H. 2012. Hymenenopsis heterophylla gen. et sp. nov. (Delesseriaceae, Rhodophyta) from New Zealand, based on a red alga previously known as Hymenena palmata f. marginata sensu Kylin, with emphasis on its cystocarp development. Phycologia 51: 62–73. DOI: 10.2216/11-38.1The alga known as Hymenena palmata f. marginata (Harvey) Kylin has been thought to be confined to the northern part of the South Island and the southern part of the North Island of New Zealand and is represented by a variety of thallus forms. The pattern of its apical growth is similar to that of Hymenena palmata (Harvey) Kylin, a poorly known species that is said to be widespread throughout New Zealand. As a consequence, H. palmata f. marginata has been misplaced under Hymenena for a long time. Unlike many species of Hymenena, the thallus branches entirely from the margins and lacks both macroscopic nerves and microscopic veins. Phylogenetic analysis of rbcL sequence data shows that, while H. palmata f. marginata is a member of the subfamily Phycodryoideae, it belongs in the Phycodryeae rather than the Cryptopleureae, a tribe that includes Hymenena, where it might otherwise be placed based on its gross morphology and growth by means of a marginal meristem with many obliquely dividing marginal cells. Procarp and cystocarp development are similar to that of the Phycodryeae, and the carposporangia are formed in chains rather than terminally as in Hymenena. The cystocarp of H. palmata f. marginata is unusual in that cells derived from the cystocarp floor form secondary pit connections with a large central fusion cell. We propose the name Hymenenopsis heterophylla S.-M. Lin, W.A. Nelson & Hommersand gen. et sp. nov. for this New Zealand red alga.