Three-celled Carpogonial Branches Research Articles

Fredericqia (Phyllophoraceae, Rhodophyta) in the northwestern Pacific, with the description of Fredericqia chiharae sp. nov.

ABSTRACT We describe a new species of Fredericqia (Phyllophoraceae, Rhodophyta) from the Choshi Peninsula, Japan (previously listed as ‘Gymnogongrus incurvatus nom. nud.’) based on morphological and molecular analyses. We assign the binomial Fredericqia chiharae sp. nov. to this new entity. Our combined rbcL, cox1, and 28S rDNA analyses suggested that F. chiharae belongs to genus Fredericqia, and is distinct from other Fredericqia species. Fredericqia chiharae is characterized by a flattened incurved thallus, marginal proliferations, dioecious gametophytes and a procarp consisting of a three-celled carpogonial branch situated on a supporting cell and bearing a sterile lateral on the basal cell. The cystocarpic characteristics of F. chiharae, i.e. a cystocarp loosely immersed in the medulla, the absence of secondary medullary cells around the cystocarp and the presence of multiple carpostomes, are congruent with those of Fredericqia. Fredericqia chiharae is the first representative of the genus to be reported from the northwestern Pacific.

Amphithallia, a genus with four-celled carpogonial branches and connecting filaments in the Corallinales (Rhodophyta)

ABSTRACTThe South African marine alga Amphithallia crassiuscula, previously subsumed in the widely reported Synarthrophyton patena, is here re-described as a distinct species and genus. Thalli grow as obligate epiphytes on Gelidium capense in the upper sublittoral zone (while S. patena grows on Ballia callitricha). Gametophytes are monoecious with four-celled carpogonial branches and sterile cells are borne on supporting cells (dioecious or hermaphroditic with two or three-celled carpogonial branches and sterile cells borne on hypogynous cells in Synarthrophyton). Postfertilization stages involve a connecting filament linking the carpogonium to several putative auxiliary cells, demonstrating a non-procarpic condition with apparent absence of a fusion cell. Gonimoblast filaments develop at the level of basal cells of carpogonial branches. Spermatangial mother cells remain either unbranched (cutting off spermatangia only) or develop dendroid (branched) filaments with terminal spermatangia (as in Synarthrophyton). Multiporate conceptacles develop straight pore canals lined by non-differentiated cells (conical canals with differentiated pore cells along the base in Synarthrophyton). The here described pre- and post-fertilization characters are new for the order Corallinales motivating the establishment of the new genus Amphithallia.

Neosiphonia ramirezii sp. nov. (Rhodomelaceae, Rhodophyta) from Peru

The genus Neosiphonia Kim and Lee 1999 contains approximately 30 species worldwide. Unidentified samples from Peru are here described as a new species, Neosiphonia ramirezii sp. nov., on the basis of morphological and molecular data. N. ramirezii sp. nov. is characterized by the presence of a limited prostrate system, well-developed erect filaments, rhizoids cut off from pericentral cells by cross walls, four pericentral cells that are completely ecorticate, scarce trichoblasts, inconspicuous scar cells, procarps with three-celled carpogonial branches, spermatangial branches developed from basal cells of forked trichoblasts, and spirally arranged tetrasporangia. Our new species is distinct from N. flaccidissima (Hollenberg) Kim et Lee, N. sphaerocarpa (Borgesen) Kim et Lee, and N. savatieri (Hariot) Kim et Lee from the Pacific temperate coast of South America and from 14 Neosiphonia species reported worldwide by having limited prostrate filaments attached by numerous rhizoids, dichotomous (“Y” shaped) branches in the main axes, and scarce trichoblasts. Phylogenetic rbcL analyses confirm the placement of the new taxon as a distinct species in the genus Neosiphonia.

A NEW METHOD OF CYSTOCARP DEVELOPMENT IN THE RED ALGAL GENUS CALLOPHYLLIS (KALLYMENIACEAE) FROM CHILE(1).

Traditional studies suggest that the Kallymeniaceae can be divided into two major groups, a nonprocarpic Kallymenia group, in which carposporophyte formation involves an auxiliary cell branch system separate from the carpogonial branch system, and a procarpic Callophyllis group, in which the carpogonial branch system gives rise to the carposporophyte directly after fertilization. Based on our phylogenetic studies and unpublished observations, the two groups each contain both procarpic and nonprocarpic genera. Here, we describe a new method of reproductive development in Callophyllis concepcionensis Arakaki, Alveal et Ramírez from Chile. The carpogonial branch system consists of a supporting cell bearing both a three-celled carpogonial branch with trichogyne and two-lobed "subsidiary" cells. After fertilization, large numbers of secondary subcortical and medullary cells are produced. Lobes of the carpogonial branch system cut off connecting cells containing enlarged, presumably diploid nuclei that fuse with these secondary vegetative cells and deposit their nuclei. Derivative enlarged nuclei are transferred from one vegetative cell to another, which ultimately cut off gonimoblast initials that form filaments that surround the central primary medullary cells and produce carposporangia. The repeated involvement of vegetative cells in gonimoblast formation is a new observation, not only in Callophyllis, but in red algae generally. These results call for a revised classification of the Kallymeniaceae based on new morphological and molecular studies.

Psilophycus alveatus gen. et comb. nov., a basal taxon in the Gigartinaceae (Rhodophyta) from New Zealand

Nelson W.A., Leister G.L. and Hommersand M.H. 2011. Psilophycus alveatus gen. et comb. nov., a basal taxon in the Gigartinaceae (Rhodophyta) from New Zealand. Phycologia 50: 219–231. DOI: 10.2216/10.38.1The red alga Gigartina alveata (Turner) J. Agardh was collected by Joseph Banks in New Zealand in 1769 during Captain Cook's voyage on the Endeavour (1768–1771) and was originally described as Fucus alveatus. This species forms a conspicuous band on rocky outcrops on open sandy beaches of the northern North Island in the mid-intertidal zone. The thallus is narrow, linear, channeled and repeatedly dichotomously branched, with the apices often curled and crowded, giving the plant a bushy appearance. Growth is multiaxial with the formation of parallel files of medullary filaments cross-linked by secondary pit connections in a reticulate manner. Cystocarpic plants greatly outnumber male or tetrasporangial individuals. Tetrasporangia are transformed from inner cortical cells, as in some basal lineages of Gigartinaceae, and secondary tetrasporangial filaments are absent. Spermatangial parent cells form spermatangia in clusters of four to five in pits surrounded by exerted cortical filaments. Procarps are typical for Gigartinaceae and consist of a supporting cell that bears a sterile cortical filament and a recurved three-celled carpogonial branch with the supporting cell functioning as the auxiliary cell. After presumed fertilization, cortical cells above the auxiliary cell form rosettes of small-celled filaments, and medullary cells undergo intercalary transverse divisions to produce modified cells that also bear rosettes of small-celled filaments. Gonimoblast filaments ramify through the medulla and may fuse with modified medullary cells, and carposporangial chains arise from these cells or directly from gonimoblasts. Surface cortical cells form a multiaxial meristem that surrounds the developing gonimoblasts to produce an envelope with an ostiole. A typical pericarp formed from secondary vegetative filaments is absent. In virtually every respect, the postfertilization development of the cystocarp is unique among members of the family Gigartinaceae and justifies the recognition of the new genus, Psilophycus, to contain the plant presently known as G. alveata.

Vegetative, reproductive and molecular characterization of Gloiocladia microspora (Faucheaceae, Rhodophyta)

Morphological and molecular studies of Gloiocladia microspora were carried out to confirm its position in the genus Gloiocladia. The thallus is compressed and complanately irregularly branched, and develops narrow, cylindrical segments from the apices, which give rise to new compressed branches in adult specimens. The cortex is composed of an outer section of loose anticlinal filaments, slightly arched at the base, and a single-layered subcortex of cells that form a network parallel to the thallus surface. The medulla is composed of large, longitudinally elongated, hyaline cells. Female gametophytes are procarpic with a three-celled carpogonial branch and a two-celled auxiliary cell branch, both borne on the same subcortical cell. After fertilization, a fusion cell is formed from the auxiliary mother cell, the auxiliary cell, and probably adjacent vegetative cells. Simultaneously the auxiliary cell divides to cut off the primary gonimoblast cell. Components of the mature fusion cell are indiscernible. Nutritive cells and a tela arachnoidea are conspicuous and present at the early procarp stage. Cystocarps are sessile or substipitate, ostiolate, and usually situated around the narrow segments of fronds or, sometimes, on the margins of the compressed branches that arise from narrow segments. Spermatangia are unknown. Tetrasporangia develop in raised nemathecia located on small compressed proliferations or on the narrow segments, and usually surround them. Phylogenetic analyses of partial rbcL sequences resolved G. microspora as a distinct species within the clade of other Gloiocladia species. Vegetative and reproductive morphology, together with molecular analyses support the position of G. microspora within Gloiocladia.

Taxonomy and Phylogeny of Neosiphonia japonica (Rhodomelaceae,Rhodophyta) Based on rbcL and cpeA/B Gene Sequences

Neosiphonia M.S. Kim et I.K. Lee is a rhodomelacean red algal genus that is commonly encountered in the intertidal zone of temperate waters in the world. The genus Neosiphonia, which was established based on species previously named under the genus Polysiphonia, is well distinguished by procarps bearing a three-celled carpogonial branches, spermatangial branches arising from a branch of the trichoblasts, and tetrasporangia arranged in spiral series (Kim and Lee 1999). The phylogenetic difference of Neosiphonia from Polysiphonia is clearly shown by both cladistic analyses of morphological features and phylogenetic analyses of nuclear ribosomal small subunit (SSU) region sequences (Choi et al. 2001). Recently, Neosiphonia is found in Malaysia (Masuda et al. 2001; Tani et al. 2003), Vietnam (Abbott et al. 2002), Brazil (Guimaraes et al. 2004), Hawaii (Kim and Abbott 2006), and Japan as well as Korea (Kim 2005). To date, 22 species previously placed in Polysiphonia have been transferred into Neosiphonia and 1 new species reported. Neosiphonia japonica (Harvey) M.S. Kim et I.K. Lee was originally described from Hakodate, Hokkaido, Japan, as Polysiphonia japonica by Harvey (1856). The species has a bush-like habit, four pericental cells, cortication on axes, numerous branches, and three-celled carpogonial branches on females. The thalli occur commonly as epiphytes on other seaweeds from Korea (Kim 1995), Japan (Yoshida 1998), China (Tseng 1984), and Pacific Russia (Perestenko 1994). Despite studies on the morphology (Yoon 1986; Kudo and Masuda 1986; Kim 1995), life history (Kudo and Masuda 1986), lectotypification (Masuda et al. 1995), and distribution (Kim 1995), the taxonomy of N. japonica is still problematic. Kudo and Masuda (1986) reported that N. japonica (as Polysiphonia japonica) is very similar to N. harlandii (Harvey) M.S. Kim et I.K. Lee, N. decumbens (Segi) M.S. Kim et I.K. Lee, and P. akkeshiensis Segi. Yoon (1986) also concluded N. savatieri (Hariot) M.S. Kim et I.K. Lee, P. forfex Harvey and N. teradomariensis (Noda) M.S. Kim et I.K. Lee as varieties of N. japonica, based on the number of pericentral cells and the presence or absence of cortication at the base. Recently, McIvor et al. (2001) proposed that N. japonica, together with P. akkeshiensis Segi, P. acuminata N.L. Gardner and P. strictissima J.D. Hooker & Harvey were conspecific with N. harveyi (J. Bailey) M.S. Kim, H.G. Choi, Guiry & Algae Volume 21(3): 287-294, 2006

Taxonomic notes on Hawaiian Polysiphonia, with transfer to Neosiphonia (Rhodomelaceae, Rhodophyta)

After detailed observations of type material and other collections, five Hawaiian species of Polysiphonia Greville, nom. cons. are recognized to be species of Neosiphonia M. S. Kim et I. K. Lee; namely, Neosiphonia apiculata (Hollenberg) Masuda et Kogame, Neosiphonia beaudettei (Hollenberg) M. S. Kim et Abbott, comb. nov., Neosiphonia hawaiiensis (Hollenberg) M. S. Kim et Abbott, comb. nov., Neosiphonia profunda (Hollenberg) M. S. Kim et Abbott, comb. nov., and Neosiphonia rubrorhiza (Hollenberg) M. S. Kim et Abbott, comb. nov. These five species are ecorticate, having lateral branch initials and trichoblasts produced on successive segments, rhizoids separated from pericentral cells by a cross wall, three-celled carpogonial branches (not seen in N. beaudettei and N. rubrorhiza), spermatangial branches arising on a primary branch of the trichoblasts, and tetrasporangia in a spiral series. Although certain characters were not available for some species, all other characters occur in a combination that is unique for members of Neosiphonia.

Vegetative and reproductive morphology of Kallymenia patens (Kallymeniaceae, Rhodophyta) in the Mediterranean Sea

Reproductive morphology of the Mediterranean red alga Kallymenia patens is described for the first time, confirming its position in the genus. K. patens is characterized by a non-procarpic female reproductive apparatus, carpogonial branch systems consisting of supporting cells bearing both three-celled carpogonial branches and subsidiary cells that lack a hypogynous cell and carpogonium; fusion cells develop numerous connecting filaments, and tetrasporangia are scattered over the thallus and are probably cruciately divided. Old fertile spathulate specimens of K. patens are morphologically similar to K. spathulata, but they can be distinguished by the length of spathulated proliferations (up to 0.6 cm and 6 cm, respectively), the length of inner cortical cells (up to 70 and 30 mm, respectively), and the gonimoblast location (in proliferations from the perennial part of the blade and over all the thallus surface, respectively).

Dasya atropurpurea sp. nov. (Ceramiales, Rhodophyta), a deep-water species from the Hawaiian Archipelago

P.S. Vroom. 2005. Dasya atropurpurea sp. nov. (Ceramiales, Rhodophyta), a deep-water species from the Hawaiian Archipelago. Phycologia 44: 572–580.Dasya atropurpurea sp. nov. is the 11th and largest known species of Dasya to occur on tropical central Pacific islands. The species is reported only from deep-water habitats between 20 and 170 m depths around the Hawaiian island chain and exhibits anatomical and reproductive features substantially different from the five other described species of Dasya in Hawaii. Critical comparison of features present in D. atropurpurea to original species diagnoses, herbarium specimens, and published descriptions of the other 75 recognized species of Dasya revealed the new species' overall stature, the development of three-celled carpogonial branches, the occasional but regular occurrence of adventitious branches, and the thin, lax, terminally tufted pseudolateral branches to be unique to D. atropurpurea.Based on anatomical features, the closest relatives of D. atropurpureaare most likely D. extensa and D. villosa.

Morphology and reproduction of Predaea feldmannii Børgesen (Nemastomataceae, Rhodophyta), an uncommon species from Brazil

The coast of Espirito Santo State is located in a biogeographic transition zone presenting high diversity. A renewed interest in this region occurred in the 1990s, resulting in various new records and new species descriptions added to the Brazilian marine flora. The study of the infralitoral of this region is just beginning, and a detailed exploration with use of Scuba diving is revealing a flora containing many little-known taxa, particularly of red algae. As a first result, Predaea feldmannii Borgesen is being described for the Brazilian coast. The occurrence of the genus Predaea in Brazil has been considered with restriction since representatives of this genus had been referred only once by Howe & Taylor in 1931, being first considered as Platoma. The occurrence of Predaea in Brazil is now confirmed, and its vegetative and reproductive structures are described in detail. Predaea feldmannii can be recognized by having gonimoblast initial formed on a bulge of the connecting filament, cortical filaments of nearly equal lengths, lack of gland cells, dense clusters of nutritive cells borne only on cells immediatelly contiguous to the auxiliary cell, and a three-celled carpogonial branch.

Observations on reproductive morphology and new records of Rhodomelaceae (Rhodophyta) from the Canary Islands, including Veleroa complanata sp. nov.

Polysiphonia funebris and P. tenerrima are examined mainly in relation to their vegetative and reproductive features. In P. funebris the procarps and cystocarps are described for the first time, and it is confirmed that the species exhibits all the vegetative and reproductive features presently used in the delineation of the genus Polysiphonia. The mainly Mediterranean P. tenerrima is reported for the first time in the Atlantic Ocean. This epi-endophyte on Nemalion helminthoides has ecorticate axes with four pericentral cells, abundant trichoblasts spirally ananged, rhizoids cut off from pericentral cells, tetrasporangia produced in spiral series and apparently three-celled carpogonial branches, all diagnostic characters of the genus Neosiphonia. Tetrasporangial plants in the western Atlantic species Dipterosiphonia reversa are described for the first time from a collection that represents the first record of this species in the eastern Atlantic Ocean. Tetrasporangia are produced (one per segment) in short linear series in pinnate laterals, with fertile segments consisting of five pericentral cells; the fertile pericentral cell cuts off two sporangial cover cells. Veleroa complanata Afonso-Carrillo & Rojas-González sp. nov., known only from Tenerife in the Canary Islands, is unique among species of the genus Veleroa because of its progressively corticated polysiphonous axes and its two different types of spirally arranged, determinate, pigmented, persistent trichoblasts. These are unbranched in prostrate and fertile portions of erect axes, but branched, with up to eight alternate-distichous complanate laterals, in vegetative erect axes. A comparative table of the morphological attributes of the species currently accepted in Veleroa is given.

Neosiphonia flavimarina gen. et sp. nov. with a taxonomic reassessment of the genus Polysiphonia (Rhodomelaceae, Rhodophyta)

SUMMARY Vegetative and reproductive development of Neosiphonia flavimarina gen. et sp. nov. (Rhodomelaceae, Ceramiales) from Bangpo on the western coast of Korea was investigated. This species is superficially similar to Polysiphonia, but differs distinctly from the latter in vegetative and reproductive structures. The plants attach by a solid disk composed of a dense cluster of rhizoids cut off from the pericentral cell wall, and bear erect indeterminate branches producing the lateral-branch initials from successive segments in a spiral arrangement. The procarps have a three-celled carpo-gonial branch. Spermatangial branches are formed on a primary branch of the trichoblasts, terminating in a single or occasionally two large, sterile cells. Tetra-sporangia are produced from the second pericentral cell adjacent to the trichoblast basal cell on indeterminate branches, and arranged spirally. Comparing several taxonomic characters among related genera, Neosiphonia occupies an independent phylogenetic position from Polysiphonia and leads to the conclusion that the genus may have a strong link with Fernandosiphonia which has a unilateral branching system. Relevant nomenclatural changes for several Polysiphonia species are also proposed.

Life history of Gymnogongrus griffithsiae (Phyllophoraceae, Gigartinales) from Ireland: implications for life history interpretation in the Rhodophyta

Abstract Tetraspores of the marine red alga Gymnogongrus griffithsiae (Turner) Martius (Phyllophoraceae, Gigartinales), the type species of the genus Gymnogongrus, gave rise in culture to erect, multiaxial, dichotomously divided thalli that developed into monoecious gametophytes. Procarps consisted of a large supporting cell and a three-celled carpogonial branch provided with a one- or two-celled sterile branchlet. Fertilized carpogonia fused with auxiliary cells, and initials of inwardly growing filaments were cut off from the auxiliary cells. Outwardly growing filaments subsequently developed from some parts of the inwardly growing filaments and directly from the auxiliary cells. They penetrated into the cortex of the erect axes and gave rise to pustule-like tetrasporoblasts, which in due course produced intercalary, seriate tetrasporangia in distinct sori. Released tetraspores developed into plants similar to those of the first generation. The relative fluorescent intensity of nuclear DNA stained with ...

Carposporangial development in the red alga Scinaia pseudocrispa ( S. forcellata) from India

The three-celled carpogonial branch of Scinaia pseudocrispa (Clemente) Wynne ( S. forcellata Bivona-Bernardi) consists of a basal cell, a hypogynous cell and a carpogonium. After fertilisation, the trichogyne severs and shrivels. The zygote nucleus is transferred from the carpogonium to the hypogynous cell. The gonimoblast initials arise from the hypogynous cell. A polysaccharidic envelope provides an isolated and protective environment for the carposporophyte and thus enables it to develop within the confines of the gametophyte. The carpospores are released through a well developed ostiole.

The Red Algae Genus Callophyllis Kützing (Kallymeniaceae, Gigartinales) from Eastern Mainland Australia, with Notes on the Genus Ectophora J. Agardh

Two species attributable to Callophyllis, a genus only recently recorded from eastern mainland Australia, are described from subtidal habitats in New South Wales. One of the species closely conforms to the New Zealand endemic Callophyllis ilepressa (J. Agardh) Laing, formerly the type species of the genus Ectophora J. Agardh. Although full reproductive details of this species are lacking, evidence in this survey strongly suggests that the genus was and is correctly placed in synonymy with Callophyllis. Thalli of C. depressa consist of prostrale, spreading, imbricate blades firmly anchored to rocky substrata by numerous haptera arising from the under surfaces. Upper frond surfaces are iridescent in localised patches corresponding to nests of refractive subcortical cells. The outer cortex in cross section comprises three to six layers and is composed of anticlinal filaments lacking secondary pit connections. The medulla consists of large, subisodiametric cells interspersed with narrow filaments. Plants appear to be procarpic, the supporting cells bearing a single three-celled carpogonial branch and several elaborately lobed, elongated, sterile cells. The second species is named Callophyllis nana sp. nov. for its diminutive (1.5 to 3 cm in length) fronds. Blades overlap, anastornose, and attach to rocky or bryozoan substrata by a single basal holdfast. The cortex is single-layered, the medulla being one to several layers of large subisodiametric cells interspersed with narrow filaments. Plants appear to be procarpic, the supporting cells bearing a single three-celled carpogonial branch and several relatively unlobed, short, bulbous sterile cells. Because of the inclusion of Ectophora into Callophyllis, the new name Callophyllis laingiaiia is proposed to replace Callophyllis dichotoma (J. Agardh) Laing [non C. dichotoma (Hooker et Harvey in Hooker) Kützing].

Contribution à l'étude du genre Predaea (Rhodophyta) en Méditerranée

Abstract A study of different populations of Predaea (Gymnophloeaceae, Rhodophyta) in the Mediterranean Sea confirms the existence of two species: P. ollivieri J. Feldmann and P. pusilla (Berthold) J. Feldmann. Not collected since its original description from Naples, P. pusilla has been rediscovered in several areas of the Western Mediterranean Sea and in the Adriatic Sea. The characters of these species are described. Predaea ollivieri, which has the gonimoblast inserted on the connecting filament, differs from P. bisporifera Kajimura, P. masonii (Setchell et Gardner) G. De Toni and P. subpeltata Dawson, both in morphology (thallus subdichotomous to irregularly branched) and in the number of nutritive cells (3–15 per bearing cell). Predaea pusilla, which has a gonimoblast inserted laterally on the auxiliary cell, differs from P. kraftiana Millar et Guiry in its three-celled carpogonial branches without a lateral sterile cell, in the fact that its carpogonium does not divide transversely after fertilizat...

Two new species of Predaea (Nemastomataceae, Rhodophyta) from the Sea of Japan

Abstract Two new species of Predaea (Nemastomataceae, Rhodophyta) are described from the Sea of Japan. Predaea tokidae is a lobed blade with spherical to ovoid outer cortical cells, conspicuous gland cells, three-celled carpogonial branches, and gonimoblasts originating on the connecting filament adjacent to auxiliary cells. Predaea bisporijera is also a lobed blade but has linear-oblong outer cortical cells, lacks gland cells, and has two-celled carpogonial branches. Gonimoblasts also originate from connecting filaments adjacent to auxiliary cells. A unique feature of P. bisporijera is the ‘bisporangia’ formed terminally on cortical filaments of female gametophytes. The two new species are compared and contrasted with the 10 previously described species of Predaea, including the only other species from Japan, P. japonica Yoshida.

Life history and reproduction of Schmitzia hiscockiana sp. nov. (Rhodophyta, Gigartinales) from the British Isles

Abstract A complanate Schmitzia species (Calosiphoniaceae) has been found growing on subtidal cobbles in the British Isles. The ephemeral erect plants are uniaxial, filamentous and gelatinous and bear spermatangia and three-celled carpogonial branches in June/July and carposporophytes from late July to September. Carpospores formed sterile crustose plants and loosely-organized filaments bearing tetrasporangia in culture at 15°C, 16: 8 h (long day, LD). Obliquely cruciate to irregularly zonate tetrasporangia were formed on the crustose plants after transfer to 10 or 15°C, 8: 16 h (short day, SD). At 15°C LD some crusts, which may have been the result of inoculation of filaments from the parent gametophytes rather than germinated carpospores, formed erect filaments which grew poorly. On transfer to SD, however, normal erect axes were formed and these have not reproduced. Tetraspores released in culture formed discs which gave rise to erect axes at 10 or 15°C, SD, but not at LD. Erect axes were similar in co...

Vegetative and reproductive morphology of Hummbrella hydra Earle (Rhodophyta, Gigartinales)

Pseudoanemonia tentacula Chapman from New Zealand is synonymized with Hummbrella hydra Earle from Chile. Morphologically Hummbrella resembles the ‘Batrachospermum-type’ construction in several respects. The thallus consists of a cylindrical stipe with an array of branches (arms) at its apex. Only gametophytes have been encountered in the field. Thalli are monoecious. Spermatangia form on the epidermal cell layer of the thallus arms. Hummbrella is monocarpogonial and procarpic. The three-celled carpogonial branch becomes four-celled following a presumed fertilization and division of the carpogonium. The supporting cell is intercalary in a normal vegetative filament and functions as the generative auxiliary cell. Indirect evidence suggests that the fourth post-carpogonial branch cell cuts off a small initial containing the diploid nucleus and this fuses directly with the auxiliary cell. A single gonimoblast initial is produced from the auxiliary cell and grows thallus outwards developing a lobed carposporophyte most cells of which form carpospores. The carposporophyte is surrounded by involucral branches. In its combination of vegetative and reproductive morphology Hummbrella hydra is unique among Rhodophyta. It is placed in the Gigartinales in the monotypic family Pseudoanemoniaceae.