MORPHOLOGY AND SYSTEMATICS OF RHODOCALLIS ELEGANS, RHODOCALLIDEAE, TRIB. NOV. (CERAMIACEAE, RHODOPHYTA), FROM SOUTHEASTERN AUSTRALIA

Recent collections of Rhodocallis elegans Kützing from southeastern Australia have permitted detailed observations of vegetative and reproductive structures that reveal features not exhibited by any existing tribe of Ceramiaceae. As a consequence, we establish the new tribe Rhodocallideae based on the unispecific genus Rhodocallis. Defining characters include: 1) four periaxial cells cut off in an alternating (rhodomelaceous) sequence; 2) determinate branchlets of two types: a) persistent lateral branchlets produced from the first-formed periaxial cells, and b) deciduous transverse branchlets produced from the second and third periaxial cells, with cortical filaments issuing from all four periaxial cells; 3) first- and second-order determinate branchlets terminated by thick-walled spines; 4) indeterminate branches formed at the tips of directly converted determinate branchlets; 5) axial cells of indeterminate branches heavily corticated by a cylinder of descending rhizoidal filaments; 6) spermatangial parent cells borne directly on unmodified outer cortical cells; 7) carpogonial branches borne in series on second and third periaxial cells of modified indeterminate axes; 8) procarps lacking sterile-cell groups; 9) a single derivative of the zygote nucleus transferred from the carpogonium to the auxiliary cell directly through a tube rather than by means of a connecting cell; 10) gonimoblasts surrounded by a network of rhizoidal filaments through which the gonimolobes protrude, the carposporophyte subtended by an investment of determinate branchlets; and 11) tetrasporangia tetrahedrally divided, borne on surface cortical cells of special determinate branchlets and protruding outside the cuticular layer.     

ACROSYMPHYTON FIRMUM SP. NOV. (RHODOPHYTA,CRYPTONEMIALES), A NEW SUBTIDAL RED ALGA FROM NEW ZEALAND; DEVELOPMENTAL MORPHOLOGY AND DISTRIBUTION OF THE GAMETOPHYTE1

Acrosymphyton firmum sp. nov., is described from the northeastern coast of North 1., New Zealand. Gametophytes are spring–summer annuals which grow subtidally on cobbles. Thalli are uniaxial; each axial cell bears a whorl of four indeterminate and one determinate branchlets. Indeterminate branchlets are alternately arranged giving the thallus a distichous and feather-like appearance. Numerous corticating rhizoidal filaments are produced from the periaxial and lower whorl branchlet cells. These rhizoids entwine and obscure the main axis as the thallus develops until in the mature plant the axes have a firm consistency and lubricous texture. The carpogonial branch bearing short lateral filaments and auxiliary cell branch with terminal auxiliary cell place this new species in the genus Acrosymphyton Sjöstedt. Of the three described species in the genus, A. firmum is most similar to A. taylori. This is the first report of the genus Acrosymphyton and the only confirmed report of the family Dumontiaceae in New Zealand waters.     

Studies of the Liagoraceae (rhodophyta) of Western Australia: Gloiotrichus fractalis gen. et sp. nov. and Ganonema helminthaxis sp. nov.

Two new taxa of Liagoraceae (Nemaliales) are described from Western Australia. Gloiotrichus fractalis gen. et sp. nov. has been collected from 3–20 m depths at the Houtman Abrolhos, Western Australia. Plants are calcified, extremely lubricous, and grow to 17 cm in length. Carpogonial branches are straight, 6 or 7 cells in length, arise from the basal or lower cells of cortical fascicles, and are occasionally compound. Branched sterile filaments of narrow elongate cells arise on the lower cells of the carpogonial branch prior to gonimoblast initiation, at first on the basal cells, then on progressively more distal cells. Following presumed fertilisation the carpogonium divides transversely, with both cells giving rise to gonimoblast filaments. The distal cells of the carpogonial branch then begin to fuse, with fusion progressing proximally until most of the cells of the carpogonial branch are included. As fusion extends, the filaments on the carpogonial branch are reduced to the basal 2 or 3 cells. The gonimoblast is compact and bears terminal carposporangia. Spermatangial clusters arise on subterminal cells of the cortex, eventually displacing the terminal cells. The sequence of pre- and post-fertilisation events occurring in the new genus separates it from all others included in the Liagoraceae, although it appears to have close affinities with the uncalcified genus Nemalion. Ganonema helminthaxis sp. nov. was collected from 12 m depths at Rottnest Island, Western Australia. Plants are uncalcified and mucilaginous, the axes consisting of a few (< 10) primary medullary filaments, each cell of which gives rise to a cortical fascicle at alternate forks of the pseudodichotomies borne on successive medullary cells. Subsidiary (adventitious) filaments and rhizoids comprise the bulk of the thallus. Carpogonial branches are straight, (3-)4(-6) cells in length, arise on the basal 1–4 cells of the cortical fascicles, and are frequently compound. Carposporophytes develop from the upper of two daughter cells formed by a transverse division of the fertilised carpogonium. Ascending and descending sterile filaments girdle the carpogonial branch cells and arise mostly on the supporting cell prior to fertilisation. Ganonema helminthaxis is the first completely non-calcified member of the genus, and its reproductive and vegetative morphology supports the recognition of Ganonema as a genus independent from Liagora. Liagora codii Womersley is a southern Australian species displaying features of Ganonema, to which it is transferred.     

Seasonal patterns of cell-to-cell communication in Chara corallina Klein ex Willd. II. Cell-to-cell communication during the development of antheridia

Cell-to-cell communication has been studied in lateral branches and developing antheridia of male Chara corallina plants. The moving cytoplasm is specialized to include essentially separate ascending and descending cytoplasmic streams within the inter-nodes. The neutral line which demarcates the ascending from the descending stream is established by the divisions of the nodal initial, which gives rise to both the node and internode. The ascending stream is located beneath the first-formed node-cells and the descending stream beneath the last-formed cells. The cells destined to develop into antheridia were always located on the same side as the descending internodal stream, and thus, were derived from the cells last formed during divisions of the nodal initial. Three stages of anther idial development have been defined: (1) young antheridia from the initial division of a node-cell to the formation of an octant structure; (2) maturing antheridia where differentiation into shield, manubria and capitular cells has occurred, including antheridia where an internal cavity has formed but contains filaments of less than 32 cells; and (3) mature antheridia where filaments contain more than 32 cells and spermatid production commences. Internodal cells of branches bearing young antheridia had similar characteristics to spring branches, including high plasmalemma potential differences (-217·7±31·5mV, [K⁺]_o 0·5 mol m^?3; pH 7·6) and extensive cell-to-cell communication (frequency of intercellular transport of 6 carboxyfluorescein 86%). The small probe 6 carboxy fluorescein moved into the entire young antheridium in 100% of injections. The molecular exclusion limit for internodes and the nodal complex lay between 874 and 1678Da whereas the exclusion limit for the young antheridium was smaller (between 750 and 874Da). Internodal cells of branches bearing maturing antheridia had similarly high PDs (–221·7±40mV; [K⁺]_o 0·5 mol m^?3; pH 7·6). Cell-to-cell communication between internodes bearing maturing antheridia was extensive (frequency of intercellular transport of 6 carboxyfluorescein 100%). The shield cells were isolated from the symplast of the thallus at this stage since they did not admit 6 carboxyfluorescein. Internodal cells of branches bearing only mature antheridia showed different characteristics. Intercellular communication between internodes was restricted to a level similar to that found in winter (frequency of intercellular transport of 6 carboxyfluorescein = 57%). The mature antheridium was entirely isolated from the symplast of the thallus. A period of extensive cell-to-cell communication and high PDs in internodal cells commences in vegetative lateral branches in spring, immediately before reproductive structures are initiated. These features persist throughout summer whilst reproductive structures develop, until the antheridial filaments contain 32 or more cells (mature stage), at which point spermatid production commences and the antheridium is isolated from the thallus. In autumn, following the stage of mature antheridia, no further antheridia are initiated. Internodes are subsequently vegetative throughout winter and their lateral branches are characterized by restricted cell-to-cell communication, low internodal PDs, and little obvious growth, all features consistent with winter dormancy.     

New records of Gelidiella pannosa, Pterocladiella caerulescens and Pterocladiella caloglossoides (Rhodophyta, Gelidiales) from Japan

Three gelidialean species, Gelidiella pannosa (Feld‐mann) Feldmann et Hamel, Pterocladiella caerulescens (Kutzing) Santelices et Hommersand and Pterocladiella caloglossoides (Howe) Santelices, are newly reported from Japan, and their characteristic features are described. Monoecious plants of P. caerulescens produce spermatangial sori on: (i) fertile cystocarpic branchlets; (ii) special spermatangial branchlets on a cystocarpic axis; and (iii) branchlets of a special spermatangial axis. The latter two are newly reported in this species. Gelidiella pannosa has numerous unicellular independent points of attachment, whereas P. caerulescens and P. caloglossoides have the peg type of secondary rhizoidal anchorage. In the molecular phylogenetic study using small subunit ribosomal DNA sequences, G. pannosa is included in the Gelidiella clade with 100% bootstrap support in neighbor‐joining (NJ) analysis and 99% in maximum parsimony (MP) analysis. Pterocladiella caerulescens and P. caloglossoides are included in the Pterocladiella clade with 99.7% bootstrap support in NJ analysis and 100% in MP analysis. Each type of secondary rhizoidal attachment is completely consistent with the respective genus clade, which suggests that this morphological characteristic reflects phylogeny within the order Gelidiales.     

Morphogenesis in the red alga,Griffithsia pacifica: Regeneration from single cells

Summary The regeneration of plants of the red alga Griffithsia pacifica from single, isolated cells is described. Regeneration can start from any cell and is triggered by the removal of an abutting cell. An isolated, single shoot cell forms a shoot and a rhizoidal cell within one day. The shoot then adds new cells by apical division at the rate of 1–2 cells/day; branches are formed at predictable but not fixed locations by budding of subapical cells. Each shoot cell enlarges for 6–8 days. The resulting plant consists of uniseriate, pseudodichotomously-branched shoot filaments with multicellular rhizoidal filaments at their base. The predictability and rapidity of this development combined with the large size of these cells (1.0×0.2 mm) facilitate developmental studies on this organism.     

Atypical development of Chaetomorpha antennina in culture (Cladophorales,Chlorophyta)

The green seaweed genus Chaetomorpha is characterized by unbranched filaments. Molecular phylogenetic data indicate that Chaetomorpha forms a clade that is nested in a paraphyletic assemblage of branched species (Cladophora). It follows that the unbranched condition is evolutionarily conserved and likely evolved early in the evolution of this clade. In this study we show that under laboratory culture conditions, the filaments of C. antennina frequently produce lateral branches, similar to Cladophora. Our results thus indicate that the unbranched thallus architecture is not entirely genetically constrained, but at least in part subject to morphological plasticity. Additionally, culture observations of C. antennina allowed a detailed study of rhizoidal development, which seems unique among Cladophorales.     

Verosphacela silvae sp. nov. (Onslowiaceae, Phaeophyceae) from the Mediterranean Sea

We describe Verosphacela silvae sp. nov., from the Mediterranean Sea. It consists of horizontal filaments living on the lower face of the red alga Peyssonnelia rubra (Greville) J. Agardh, from which erect filaments up to 1.5 mm high rise and grow upright after passing through the thallus of the supporting species. There are both horizontal and erect filaments growing by apical cells. In the subapical cells, 1–2 longitudinal divisions occur (more frequently in the erect filaments) but no secondary transverse divisions occur. Erect filaments bear lateral propagules on a stalk of one to three (rarely more) cells. Propagules, with neither apical cells nor arms, consist of seven cells. Zoidangia are borne at the apex of erect laterals. The new species differs from V. ebrachia Henry mainly in habit, propagules and zoidangia. In addition, distinct from V. ebrachia, filaments of V. silvae never penetrate between the cuticle and the cell wall of the supporting alga. Moreover, propagules of V. silvae consist of seven cells, whereas those of V. ebrachia consist of 9–13 cells, and zoidangia are terminal on laterals in V. silvae, whereas in V. ebrachia they are sessile on both axes and laterals.     

Leaf Ontogeny in Digitaria eriantha

The shoot apex consists of two layers, the dermatogen and thehypodermis. The leaf primordia arise through periclinal divisionswithin these two layers on the side of the apex. Further divisionsof the dermatogen push the little protuberance upward and togetherwith divisions the hypodermis add internal tissues of the youngleaf. When the median and lateral bundles of the primordia arisein Digitaria eriantha they are isolated from the vascular supplyof the rest of the plant. The median strand, the first to form,and the first order laterals form at the disc of insertion ofthe primordium. The other laterals form higher up in the primordium.These strands extend both acropetally and basipetally to linkwith the vascular supply of the rest of the plant. Digitaria eriantha, apical meristem, leaf primordium, vascular bundle, orange G, tannic acid, iron alum     

DIOECY IN BAUHINIA RESULTING FROM ORGAN SUPPRESSION

Bauhinia malabarica and B. divaricata have both been reported to have dimorphic flowers; floral development of these species has been investigated and compared using SEM. B. malabarica is subdioecious, with three types of flowers: perfect, staminate, and carpellate. Individual trees usually have only one type of flower. Perfect and carpellate flowers have similar initiation of floral organs; each has five sepals, five petals, two whorls of five stamen primordia and a carpel primordium. The carpels of carpellate flowers do not differ from those of perfect flowers throughout development. Both have a gynophore or stipe and a cuplike hypanthium. Stamen development diverges markedly after mid-development: the perfect flowers have ten stamens in two whorls, the outer with longer filaments than the inner. All stamens have anthers, which are covered abaxially with abundant inflated trichomes. Carpellate flowers have a circle of short cylindrical staminodia, each bearing a few hairs, about the base of the carpel on the rim of the hypanthium. Heteromorphy in B. malabarica is effected by suppression of stamen development, even though the usual number of stamen primordia is initiated. Suppression of stamens occurs at midstage in development in carpellate flowers of B. malabarica, and is complete. In B. divaricata nine stamen primordia are released from suppression in late stage, undergo intercalary growth and form a staminodial tube around the carpel stipe. The dimorphy in B. divaricata is expressed late in bud enlargement as divergent rates of growth in the carpel in the two morphs.     

‘Endong’, a rare variety of the farmed carrageenophyte Eucheuma denticulatum (Burman) Collins & Hervey from the Philippines

The variety described in this paper is rather a rare and interesting one. Locally called ‘endong’, this was discovered first in a farm in Tawi-Tawi, Sulu Archipelago, Philippines. During harvest, seaweed farmers used to mix this with ‘tambalang’ (Kappaphycus alvarezii (Doty) Doty ex Silva var. tambalang Doty, the ‘cottonii’ of commerce) because of the presumption of it producing the same carrageenan type as that of ‘tambalang’, viz., kappa-carrageenan. The two farmed varieties are similar in appearance. Complaints arose from seaweed processing plants when the resulting gelling properties (hard and brittle gel) expected of the kappa-carrageenan-producing ‘tambalang’ were not met. Because of its lax habit and long, smooth, and naked basal axes, ‘endong’ was initially thought to be related to ‘tambalang’ and differ from the farmed ‘spinosum’ (Eucheuma denticulatum (Burman) Collins & Hervey) whose typical or common form has shorter axes covered from base to apex with spinous determinate (ramuli) or indeterminate branchlets arranged irregularly and in whorls at predictable interval. However, a closer look at ‘endong’ shows that it also has spinous branchlets arranged in whorls, but confined to the apical portion of the branches. Moreover, its internal axial anatomy shows rhizoidal filaments forming a core. Both characters fit well the distinguishing taxonomic criteria established for E. denticulatum. Chemical characterization of its carrageenan and the determination of its phylogenetic affinities support our morphological findings. Hence, we report and describe ‘endong’ as a rare variety, and we name it E. denticulatum (Burman) Collins & Hervey var. endong Trono & Ganzon-Fortes var. nov. Tips to distinguish ‘endong’ from ‘tambalang’ are included in this paper to aid seaweed farmers in separating the two during harvest.     

Life History,Reproductive Morphology and Development of the Antarctic Brown Alga Desmarestia menziesii J. Agardh*

The life history, reproduction and development of Desmarestia menziesii J. Agardh from Antarctica is described. Unilocular sporangia occur singly or in small groups in the outermost cortical layer of the sporophyte. They are formed by periclinal division of cortex cells into a stalk cell and the sporangium initial. Meiospores germinate into dioecious microscopic filamentous gametophytes. As in other perennial Antarctic species of the Desmarestiales, gametangia are formed in culture under short-day conditions or in darkness. In nature, juvenile sporophytes should therefore be formed in winter. They develop only attached to the oogonium. At first they are uniseriate and elongate by means of an intercalary meristem located in their middle part. Laterals are formed predominantly in this region, and they subsequently give rise to secondary laterals. The branching pattern is opposite to alternate in both young and adult plants. Cortication of the main axis is initiated by filaments growing out from the lowermost cells of the primary laterals. In sporophytes of this developmental stage the meristem of the main axis is confined to a small region where cortication starts and above. Lateral branches elongate and become corticated in the same way as the main axis. In mature plants, cells of the inner cortex can become meristematic again and form a meristoderm which contributes to axis thickness by periclinal and anticlinal divisions. The observations are discussed in relation to possible evolutionary relationships in the genus Desmarestia and in the order Desmarestiales.     

金针菇信息素信号通路基因在子实体发育过程中的差异表达

【背景】子实体是食用菌的主要商品部位,也是真菌生殖生长的重要结构,其发育受到多种信号途径的调控。【目的】以金针菇(Flammulina filiformis)为材料,对转录组和基因组数据的信息素信号通路基因进行分析获得差异表达的基因,并对其在菌丝生长和子实体发育过程中的表达情况进行分析,以期为研究食用菌子实体发育提供参考。【方法】基于已有的金针菇基因组数据,注释了金针菇信息素信号通路。进一步通过转录组测序鉴定了该通路中参与金针菇子实体发育的关键基因,并对关键基因进行荧光定量PCR验证。【结果】cdc24和ste12基因在子实体发育不同时期的5个样品(原基、伸长期菌柄、伸长期菌盖、成熟期菌柄和成熟期菌盖)中的表达具有显著差异,使用荧光定量PCR技术进行验证与上述结果一致。【结论】cdc24和ste12这2个关键基因可能参与了金针菇子实体发育过程中的组织分化调控机制。     

Sur la culture des spores et le développement du thalle de Botryocladia chiajeana (Menegh.) Kylin (Rhodyméniales,Rhodyméniacées)

Abstract

On the culture of spores and the development of the thallus of Botryocladia chiajeana (Menegh.) Kylin (Rhodymeniales, Rhodymeniaceae). - The complete development of Botryocladia chiajeana has been studied in culture. Spore germination and sporeling development is of the discalis mediatus type described by Inoh (1947). The hollow vesiculous branches filled with a mucilage derive from the spacing of the erect filaments which form the stipe. The authors compare this development of the thallus with that described for other Rhodymeniales.     

A NEW AGAROPHYTE SPECIES,GELIDIUM EUCORNEUM SP. NOV. (GELIDIALES,RHODOPHYTA), BASED ON MOLECULAR AND MORPHOLOGICAL DATA1

Gelidium is an economically and ecologically important agar‐producing genus. Although the taxonomy of Gelidium has been the focus of many published studies, there is still a need to reevaluate species‐level diversity. Herein, we describe Gelidium eucorneum sp. nov. based on specimens collected off Geojedo on the southern coast of Korea. G. eucorneum is distinguished by cartilaginous thalli with brush‐like haptera, rhizoidal filaments concentrated in the medulla, and globose cytocarps that are horned with multiple determinate branchlets. The species occurs in wave‐exposed intertidal sites, sometimes in association with other mat‐forming algae. Phylogenetic analyses (rbcL, psaA, and cox1) reveal that G. eucorneum is unique and clearly distinct from other species of the genus. The clade containing Gelidium vagum and Acanthopeltis longiramulosa was resolved as a sister group to G. eucorneum. We suggest that the diverse morphologies of G. eucorneum, G. vagum, and Acanthopeltis developed from a common ancestor in East Asian waters. This study shows that even in well‐studied areas, more agarophyte species are to be added to the world inventory of red algae.     

Metabolite changes during the life history of Porphyra haitanensis

Plant metabolomics is essentially the comprehensive analysis of complex metabolites of plant extracts. Metabolic fingerprinting is an important part of plant metabolomics research. In this study, metabolic fingerprinting of different stages of the life history of the red alga Porphyra haitanensis was performed. The stages included conchocelis filaments, sporangial branchlets, conchosporangia, discharged conchospores and conchosporangial branchlets after conchospore discharge. Metabolite extracts were analysed with ultra‐performance liquid chromatography coupled with electrospray ionisation quadrupole‐time of flight mass spectrometry. Analyses profiles were subjected to principal components analysis and orthogonal projection to latent structures discriminant analysis using the SIMCA‐P software for biomarker selection and identification. Based on the MS/MS spectra and data from the literature, potential biomarkers, mainly of phosphatidylcholine and lysophosphatidylcholine, were identified. Identification of these biomarkers suggested that plasma membrane phospholipids underwent major changes during the life history of P. haitanensis. The levels of phosphatidylcholine and lysophosphatidylcholine increased in sporangial branchlets and decreased in discharged conchospores. Moreover, levels of sphingaine (d18:0) decreased in sporangial branchlets and increased in discharged conchospores, which indicates that membrane lipids were increasingly synthesised as energy storage in sporangial branchlets, while energy was consumed in sporangial branchlets to discharged conchospores. A metabolomic study of different growth phases of P. haitanensis will enhance our understanding of its physiology and ecology.     

Origin of Epidermis and Development of Root Primordia in Pistia, Hydrocharis and Eichhornia

All three floating plants have roots bearing laterals derivedfrom both pericycle and endodermis. In Pistia and Eichhornialaterals arise within the meristem of the mother root; in Hydrocharisthey arise from mature tissue. In Pistia and Hydrocharis theepidermis becomes anatomically discrete between cortex and cap:in Pistia it is derived from the endodermis of the mother root,in Hydrocharis from the pericycle. The epidermis is not discretein Eichhornia and is derived from the pericycle of the motherroot with the cortex. Stathmokinetic data were used to construct timetables of developmentwhich show how the differences arise. In Pistia the first periclinaldivision of the endodermis-derived tissue individualizes theepidermis and occurs early, before a quiescent centre forms.In Hydrocharis the epidermis also becomes discrete before thepole of the meristem becomes quiescent, but it does so by apericlinal division of the pericycle-derived tissue. In Eichhorniapericlinal divisions occur in the outermost layer of the pericycle-derivedtissue long after quiescence has set in at the pole and afterthe fourth periclinal division in the endodermis derived cap.Its epidermis therefore never becomes anatomically discretethough it becomes functionally discrete because its polar cellsstop dividing as in the other plants. The involvement of the endodermis of mother roots in the formationof laterals is discussed in relation to the state of differentiationat sites of primordium formation, discreteness of the epidermisand subsequent fate of primordia. Pistia stratiotes L., Hydrocharis morsus-ranae L., Eichhornia crassipes Solms., primordia, lateral root, discrete epidermis, development, chimera, stathmokinetics     

Comparative morphology and systematics of Chondrymenia lobata from the Mediterranean Sea and a phylogeny of the Chondrymeniaceae fam. nov. (Rhodophyta) based on rbcL sequence analyses

The Chondrymeniaceae Rodríguez-Prieto, G. Sartoni, S.-M. Lin & Hommersand, fam. nov., is proposed for Chondrymenia lobata. Analyses of rbcL sequences place the new family in a large gigartinalean assemblage that comprises the Cystocloniaceae–Solieriaceae complex. Plants are decumbent and growth takes place by division of multiple apical cells at the margin of the blade. Thalli consist of an outer cortex of subspherical to elongate cortical cells arranged in anticlinal rows, a subcortex of cells cross-linked by lateral arms, and a large central medulla composed of primary medullary filaments intermixed with numerous rhizoidal filaments. Male stages are reported in monoecious individuals. Inactive carpogonial branches consist of a two-celled filament that is directed inwards from the supporting cell. Functional carpogonial branches are oriented outwardly, with the carpogonia and trichogynes pointed towards the thallus surface. After presumed fertilization, the carpogonium fuses with the hypogynous cell and transfers the zygote nucleus. The hypogynous cell, in turn, fuses with the supporting cell which contains many haploid nuclei. The resulting fusion cell functions as an auxiliary cell that cuts off a single gonimoblast initial, which produces the gonimoblast filaments. Gametophytic cells close to the auxiliary cell unite with it to form a placental fusion network of variable size and outline, and a placental fusion cell. Proximal gonimoblast cells fuse with the placental fusion cell, while the distal cells differentiate into branched chains of subspherical carposporangia. The superficial similarity of the outwardly developed osteolate cystocarp is responsible for Kylin's (1956) placement of Chondrymenia in his family Sarcodiaceae; however, the manner in which the placenta is formed is more like that seen in the Cystocloniaceae–Solieriaceae complex.     

THE BIOLOGY OF HARVEYELLA MIRABILIS (CRYPTONEMIALES; RHODOPHYCEAE). V. HOST RESPONSES FO PARASITE INFECTION1,2

The thallus of Harveyella mirabilis (Reinsch) Schmitz & Reinke is composed of vegetative rhizoidal cells growing intrusively between adjacent cells of the red algal hosts (Odonthalia and Rhodomela) and a protruding reproductive pustule. Although primarily composed of Harveyella cells, host medullary and cortical cells also occur in the emergent pustule. In both tissue regions, Harveyella cells are connected to host cells by secondary pit connections initiated by the host. Direct penetration of host cells by rhizoidal cells of Harveyella occasionally occurs, resulting in host cell death. Degeneration of host medullary cells beneath the pustule may result in a hollow branch and the cortical cells undergo cell division forming a thick palisade layer of randomly associated, photo-synthetically active cells. It is within these branches that the parasite overwinters vegetatively. Host medullary and cortical cells dispersed in the emergent pustule show few of the degenerative responses noted in host cells adjacent to parasite rhizoidal cells. Rather, host cell division, chloroplast division and photosynthetic assimilation of H¹⁴CO^?₃ all increase. Spherical virus-like solitary bodies (S-bodies) occur in all Harveyella cells and in all host cells attached to Harveyella by secondary pit connections. The possibility that these structures may induce the infective response in the host is discussed.