A study on Gracilaria dendroides sp. nov. (Gigartinales, Rhodophyta) from the Bay of Naples

A study on Gracilaria dendroides sp. nov. (Gigartinales, Rhodophyta) from the Bay of Naples
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  This article was downloaded by: []On: 21 March 2014, At: 05:42Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK British Phycological Journal Publication details, including instructions for authors andsubscription information: A study on Gracilaria dendroides sp. nov.(Gigartinales, Rhodophyta) from the Bayof Naples Gaetano M. Gargiulo a  , Flora De Masi a  & Giacomo Tripodi aa  Istituto di Botanica , Università di Messina , 2 via P. Castelli,I-98100, Messina, ItalyPublished online: 17 Feb 2007. To cite this article:  Gaetano M. Gargiulo , Flora De Masi & Giacomo Tripodi (1985) A study onGracilaria dendroides sp. nov. (Gigartinales, Rhodophyta) from the Bay of Naples, British PhycologicalJournal, 20:4, 357-364 To link to this article: PLEASE SCROLL DOWN FOR ARTICLETaylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &Conditions of access and use can be found at  Br. phycol. J. 20:357-364 1 December 1985 A Study on racilaria dendroides sp. nov. Gigartinales, Rhodophyta) from the Bay of Naples By GAETANO M. GARGIULO, FLORA DE MASI and GIACOMO TRIPODI Istituto di Botanica, Universitgt di Messina, 2 via P. Castelli, 1-98100 Messina, Italy Gracilaria dendroides sp. nov. is described from the Bay of Naples, Italy, where it thrives on the rocks in the upper littoral. The species has a typical branching pattern resulting in the dendroid habit of the plant. G. dendroides is also characterized by lanceolate branchlets which become longer and taper in the distal part of the branches. Tetrasporangia, spermatangial conceptacles and cystocarps are localized in the lanceolate branchlets. The cortex in which tetrasporangia are deeply immersed is modified, the cells being less vacuolized and with a thick cell wall. The spermatangial conceptacles are as in G. verrucosa. The gonimoblastic tissue is lobate with connective filaments to the pericarp. The morphological and structural features are considered stable thus supporting the description of a new species. According to Bird, van der Meer & McLachlan (1982), the records of Gracilaria verrucosa (Hudson) Papenfuss throughout the world are to be accepted with some reservation because of the incomplete characterization of this species (Dixon & Irvine, 1977). Some of the characters attributed to individuals collected at widely separated localities are in fact the result of a simplistic concept of this species. An example is the attribution of the epithet verrucosa to a Gracilaria from Chile showing spermatangial conceptacles which, according to the studies of Yamamoto (1975), are of the 'textorii type (Kim, 1970). Other misapplications of this epithet are reported by McLachlan (1979) and Bird, van der Meer & McLachlan (1982). The marine flora of the Bay of Naples has been investigated by Funk (1927, 1955) who reported the presence of G. verrucosa, under the synonym G. confervoides (L.) Greville. Feldmann (1967) has also included in this latter species an entity collected in the Bay of Naples which was studied by Kylin (1930) as Cordylecladia erecta (Grev.) J. Ag. and by Dawson (1949) who considered it to be a new species of Cordylecladia. The exhaustive history of this organism is reported by Feldmann (1967) and Guiry (1976). The present paper is a study of this controversial entity, which has been compared with G. verrucosa from the south coast of Britain where the holotype of this species has been collected and has led to the conclusion that they are different species. A broader comparison with other Gracilaria species lead us to conclude that this organism represents a new species, described here as Gracilaria dendroides. MATERIALS AND METHODS Observations have been carried out over a 4-year period (1981-1984) in the same locality (Posillipo) of the Bay of Naples, Italy, where the species was previously collected and where it is common in the upper littoral, just below the low tide mark. The description given in the following section is proposed after an examination of material collected by the authors and specimens from Funk's herbarium at the Zoological Station, Naples, and J. Feldmann's herbarium at the Mus6e d'Histoire Naturelle, Lab. de Crypto- gamie, Paris (PC). For a comparative study we also examined the collections of the genus Gracilaria in the British Museum (Natural 0007-1617/85/040357 + 08 $03.00/0 © 1985 British Phycological Society    D  o  w  n   l  o  a   d  e   d   b  y   [   5   8 .   2   1   5 .   5   2 .   1   5   6   ]  a   t   0   5  :   4   2   2   1   M  a  r  c   h   2   0   1   4  358 G.M. Gargiulo, F. De Masi and G. Tripodi History) in London (BM) and Erbario Centrale Italiano, Firenze (FI). Material studied was preserved in 3% formalin-seawater stored at 4°C. For microscopic examination sections of about 4~tm were obtained from Epon Araldite embedded pieces with an Ultrotome V LKB microtome equipped with glass knives. Sections were stained with Brilliant Cresyl Blue (BDH Chemicals Ltd, Poole) according to Tripodi & De Masi (1977). DIAGNOSIS Gracilaria dendroides sp. nov. Frons erecta, teres, inferne nuda, obscure di-trichotoma, quasi arborescens, atropurpurea, 300 mm longa, 1-2 mm lata. Ramulis lanceolatis atque furcatis, saepe secundatis, terminalibus elongatis. Tetra- sporangia, conceptacula spermatangifera atque cistocarpia in ramulis terminalibus locata. Tetrasporangia in mutato strato corticali, cruciatim divisa; spermatangia in conceptaculis profunde submersis, utriculo similibus; cisto- carpia hemisphaerica, sexilis. Gonimoblastus lobatus; filamenta gonimoblasti ramosa e multis et irregularibus cellulis composita. Holotypus MS 33085a in herbario messanensi (MS), in sino neapolitano ad oras Pausillipi lectus, 1 m profunditate. Thallus terete, basally unbranched, obscurely di- or trichotomously branched, dendroid, blackish-red, 300mm long, 1 2ram wide. Terminal branchlets lanceolate or dichotomously branched, elongate when terminally located. Tetrasporangia, spermatangial conceptacles and cystocarps in terminal branchlets. 2 mm i i FI6. 1. Gracilaria dendroides sp. nov., holotype MS 33085a; tetrasporic plant.    D  o  w  n   l  o  a   d  e   d   b  y   [   5   8 .   2   1   5 .   5   2 .   1   5   6   ]  a   t   0   5  :   4   2   2   1   M  a  r  c   h   2   0   1   4  Gracilaria dendroides sp. nov. 359 Tetrasporangia cruciately divided, immersed in a modified cortex. Spermatangial conceptacles of verrucosa type. Hemispheric and sessile cystocarps; gonimoblastic tissue in lobes, built up by many, branched filaments of irregularly shaped cells. Holotype: MS 33085a (Herb. G. Tripodi, Messina); tetrasporic. Isotypes: MS 33085b (Herb. G. Tripodi); cystocarpic. BM; tetrasporic. PC; tetrasporic. Type locality: Mediterranean, Bay of Naples, loc. Posillipo. Distribution: to date, the type locality. OBSERVATIONS Habit Thalli are erect, red or blackish-purple, up to 300 mm long, arising singly or in tufts from a discoid holdfast. The main axis is usually poorly branched in the proximal part, while the thallus is more densely branched in the central and distal regions (Fig. 1). The main axis is 1.0-2.5 mm in diameter and is di- or trichotomously branched, without showing any reduction in diameter. Further branching gives rise to lanceolate branchlets, sometimes secundate, usually simple, otherwise di- or trichotomizing, about 1.5 mm in width, up to 7 mm long; however, toward the distal part of the plant the branches taper and may be up to 50 mm long. The lanceolate branchlets are usually arranged in such a way that the longer ones are toward the end of the branches (Fig. 1) and the general appearance of the thallus is dendroid. Tetrasporangia are formed on lanceolate branches which appear swollen and abruptly constricted in their proximal portion, giving a clearly stalked appearance to the branches (Fig. 1). The female gametophyte bears hemispherical cystocarps 1.0mm in diam., which are located on lanceolate branchlets (Fig. 2), but no cystocarps have been observed along the main axis or on the second order branches. The male gametophyte is similarly branched and bears spermatangial con- ceptacles scattered along the lanceolate branches only (Fig. 3). Anatomy The internal structure of a vegetative plant consists of a pigmented cortex, a subcortex and a central medulla (Fig. 4). In the oldest part of the thallus the cortex is four to five- layered and generally two-layered toward the tip (Fig. 5). These pigmented cells are roughly cuboid and 7-10 gm in diameter. The subcortex consists of round cells 15-30gm in diameter. The medulla is composed of cells 180-200 gm in diameter, but those cells in contact with the subcortex are 60-70 ~tm in diameter. Tetrasporangia are cruciately divided (Fig. 6), although this is somewhat variable; the tetrasporangia are elongate and are 40-60 x 18-25 gin. They are immersed in a modified cortex, the cells of which are irregularly shaped, less vacuolized and with thick cell walls. A lobed fusion cell is present in the core of gonimoblast (Fig. 7). The proximal part of the gonimoblast filaments are associated in definitely oriented groups of irregularly- shaped and thick-walled cells, from which chains of elongated and progressively smaller cells arise, the carposporangia being the terminal ones. The carposporophyte is clearly lobed (Fig. 7) and connected with the pericarp by a number of filaments (Fig. 8). The cells forming the pericarp have a similar rounded shape, and are all clearly ordered in anticlinal and radial rows (Fig. 8). Spermatangial conceptacles are structured as in G. verrucosa, ovoid (50 x 70 lam) and immersed in the subcortical layer (Fig. 9). The outermost layer of the cortex is not modified as in the case of the tetrasporangia, while the subcortical cells limiting the conceptactes are slightly elongated. To date, plants bearing spermatangial branchlets have been collected in late summer (September), carposporangial individuals in late autumn and tetra- sporangial plants mainly in the winter and spring months.    D  o  w  n   l  o  a   d  e   d   b  y   [   5   8 .   2   1   5 .   5   2 .   1   5   6   ]  a   t   0   5  :   4   2   2   1   M  a  r  c   h   2   0   1   4  360 G.M. Gargiulo, F. De Masi and G. Tripodi 2 mm FIo. 2. G. dendroides sp. nov.; a portion of the cystocarpic isotype MS 33085b. lmm | FIG. 4. G. dendroides sp. nov.; trans- verse section of thallus. 20ram FIG. 3. G. dendroides sp. nov.; a portion of the male isotype MS 33085c.    D  o  w  n   l  o  a   d  e   d   b  y   [   5   8 .   2   1   5 .   5   2 .   1   5   6   ]  a   t   0   5  :   4   2   2   1   M  a  r  c   h   2   0   1   4
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