A SYNOPTIC KEY TO THE RHODOPHYTA OF THE WESTERN MEDITERRANEAN PART. I GIG ARTIN ALES, H AL YMENIALES, HILDENBRANDIALES AND PLOCAMIALES C Rodriguez-Prieto, M Sabater, A Vergés To cite this version: C Rodriguez-Prieto, M Sabater, A Vergés. A SYNOPTIC KEY TO THE RHODOPHYTA OF THE WESTERN MEDITERRANEAN PART. I GIG ARTIN ALES, H AL YMENIALES, HILDENBRAN- DIALES AND PLOCAMIALES. Vie et Milieu / Life & Environment, Observatoire Océanologique - Laboratoire Arago, 2001, pp.55-65. hal-03192091 HAL Id: hal-03192091 https://hal.sorbonne-universite.fr/hal-03192091 Submitted on 7 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. VIE ET MILIEU, 2001, 51 (1-2) : 55-65 A SYNOPTIC KEY TO THE RHODOPHYTA OF THE WESTERN MEDITERRANEAN PART. I GIG ARTIN ALES, H AL YMENIALES, HILDENBRANDIALES AND PLOCAMIALES C. RODRIGUEZ-PRIETO, M.A. SABATER, A. VERGÉS Universitat de Girona, Facultat de Ciències, Campus de Montilivi, s/n. 17071 Girona, Spain E-mail:cacrp @fc. udg. es RHODOPHYTES RÉSUMÉ. - Une clé dichotomique pour la détermination des Gigartinales, Halymé- GIG ARTIN ALES niales, Hildenbrandiales et Plocamiales de Méditerranée occidentale est présentée. HALYMENIALES Elle a pour objectif de faciliter la reconnaissance de ces algues rouges. Ce travail HILDENBRANDIALES PLOCAMIALES inclut l'ordre des Gigartinales, avec 69 espèces groupées en 19 familles et 35 gen- CLÉ TAXONOMIQUE res, l'ordre des Halyméniales, avec 13 espèces appartenant à 2 familles et 6 genres, STRUCTURES DE REPRODUCTION l'ordre des Hildenbrandiales, avec 1 famille, 1 genre et 3 espèces, et l'ordre des MÉDITERRANÉE DE L'OUEST Plocamiales, avec 1 famille, 1 genre et 2 espèces. Le genre Wurdermannia Harvey est inclus dans la clé, bien que son appartenance aux Gigartinales reste incertaine. Quelques descriptions morphologiques et anatomiques des structures de reproduc- tion sont aussi inclues, d'après des données de la littérature et de nos propres obser- vations. RHODOPHYTA ABSTRACT. - A synoptic key for identifying the Gigartinales, Halyméniales, Hil- GIGARTINALES denbrandiales and Plocamiales from the Western Mediterranean has been prepared HALYMENIALES in order to facilitate the récognition of thèse red algae. The orders Gigartinales, HILDENBRANDIALES PLOCAMIALES with some 69 species grouped in 19 families and 35 gênera, Halyméniales, with 13 TAXONOMIC KEY species grouped in 2 families and 6 gênera, Hildenbrandiales, with 1 family and 1 REPRODUCTIVE STRUCTURES gênera of 3 species, and Plocamiales, with 1 family and 1 genus of 2 species are in- WESTERN MEDITERRANEAN cluded. The genus Wurdermannia Harvey is also included in the key, although it has not finally been established whether it belongs to the order Gigartinales or not. Morphological and anatomical descriptions of the reproductive structures, using data from the literature and from personal observations are presented. INTRODUCTION than a single distinction. Végétative characteristics are used to separate gênera and species where ap- propriate, but as définitive identification can only This is intended to be the first publication in a rarely be obtained from gênerai appearance and séries of keys to the différent orders of benthic ma- form of the Rhodophyta, or from stérile material, rine algal flora from the western Mediterranean reproductive stages have been incorporated in un- (excluding the recently introduced species). The avoidable cases. Many of the families have a présent paper includes the order Gigartinales with highly distinctive female reproductive System from 69 species grouped in 19 families and 35 gênera, which they can be recognized, although such char- the order Halyméniales with 13 species grouped in acters may often be difficult to observe. The main two families and six gênera, the order reproductive characteristics are listed for each ge- Hildenbrandiales with one family and one genus of nus in Table I. The use of dimensions such as the three species, and the order Plocamiales, with one length and width of thalli is only a guide in the key, family and one genus of two species. The genus since such characteristics tend to be very variable Wurdermannia Harvey is also included in the key and unstable. although it has not yet been finally established Following the key is a listing of the gênera and whether it belongs to the order Gigartinales or not. species currently recognized in the studied area. The key should serve as a tool to identify gênera We have included the order Cryptonemiales and species of thèse groups. An effort has been (Kylin, 1956) in the order Gigartinales, following made to base dichotomies in the key upon more Kraft & Robins (1985), because we consider that structure Uniaxial/Multiaxial LIFE HISTORY Triphasic/Biphasic Isonnorphic/Heteromorphic FEMALE GAMETANGIA Monocarpogonial/Polycarpogonial number of cells of the carpogonial branch carpogonial branch Simple/Branched Procarpic/Non-procarpic supporting cell acting as auxiliary cells (Yes/No) auxiliary branch borne on supporting cell (Yes) auxiliary cell a nearby cortical or medullar cell (Yes) auxiliary cells in spécial filaments (Yes) carpogonial and auxiliary cells in ampullae subsidiary cells présent (Yes' carpogonial branch with nutritive auxiliary cells (Yes) auxiliary cell with adjacent nutritive cells (Yes) MALE GAMETANGIA Scattered/in Clusters/in SOri/in CHains in spécial branchlets or bladelets (Yes/No) GONIMOBLAST developing Inwards/Outwards on Auxiliary cell/on Connecting filament with involucre Cellular/Filamentous/Absent with ostiole Présent/Absent in spécial branchlets or bladelets (Yes/No) TETRASPORANGIA Cruciately/Tetrahedrally/Zonately/Irregularly arranged Scattered/in SOri/in Conceptacles in spécial branchlets or bladelets (Yes/No) Table 1 Type of structure and main reproductive characteristics of the gênera treated (sv = several); (* = usually); (? = unknown); (grey colour = unattainable characteristics). A KEY TO THE RHODOPHYTA OF WESTERN MEDITERRANEAN, PART I 57 the fact that the Cryptonemiales have auxiliary 4. Thallus brownish red. Conceptacle chamber sphe- cells in accessory Systems within the thallus, as op- rical, with a small ostiole. Tetrasporangia with pa- posed to Gigartinales supposedly transforming rallel, transverse or oblique cleavage, 5-10 x 20- végétative cells into auxiliary cells, is insufficient 30 um H. crouanii 4. Thallus purplish red. Conceptacle chamber ovoid, basis for placing the Cryptonemiales in a separate with a large ostiole. Tetrasporangia always with order. The Hildenbrandiales (Pueschel & Cole, transverse cleavage, 10-15 x 25-40 um 1982), Plocamiales (Saunders & Kraft, 1994) and H. occidentalis Halyméniales (Saunders & Kraft, 1996) are consid- 5. Hypothallus with some filaments larger than the érée! as separate orders, following récent molecular others, appearing in surface view as a more or less studies, but since their morphology and reproduc- conspicuous percurrent midrib and as a distinct cen- tive structures are similar to the Gigartinales, the tral axis in cross section. Each hypothallial cell gi- families in thèse orders are not separated in the ving rise to more than one upper and one lower coxal key. Other taxa have been separated as orders and cells. The filaments of the perithallus and subhypo- are not covered in this first part. Thèse taxa in- thallus are erect. Thallus not calcified. Gland cells cluded the Ahnfeltiales (Maggs & Pueschel, 1989), are présent, situated in the upper surface of the blade représentatives of which are not known in Western and apparent in surface view as white microscopic Mediterranean, the Corallinales (Silva & Johansen, rounded spots Family RHIZOPHYLLIDACEAE 1986), which is a clearly distinguishable order, and Genus Contarinia 6 the Gracilariales (Fredericq & Hommersand, 1989) 5. Hypothallus either sparingly branched and more or which requires more investigation in the Mediterra- less parallel (radially arranged), or much branched to nean. The taxonomic arrangement below the level form a polyflabellate layer (polyflabellately arran- of families follows Silva et al. (1996). ged), but not appearing as a distinct central axis in cross section. Each hypothallial cell giving rise to no more than one upper and one lower coxal cells. The CURRENT KEY filaments of the perithallus and subhypothallus are usually inclined towards the margin. Thallus calcified 1. Thallus prostrate, with a dorsiventral symmetry. or not. Gland cells are absent 7 Plants calcified or not. Structure consisting of a 6. Genus Contarinia single basai layer of branched filaments (hypothal- 6. Plants are flattened, forming reniform and encrus- lus), with each cell dividing into one or more upper ting fronds, irregularly branched, with sinuous cells (upper coxal cells) and, occasionally, one or and lobed margins. In longitudinal section, hypo- more lower cells (lower coxal cells). The upper coxal thallial cells up to 35 (-40) um long and 20 um cells give rise to filaments of apical growth directed broad. Erect filaments up to 10-25 um wide at ba- to the upper surface (perithallus), erect