Revision of the genus Dasya (Ceramiales, Rhodophyta) inGalicia (NW Spain) and the addition of a new alien species
Dasya sessilis Yamada for the European Atlantic coasts
by
Viviana Pea & Ignacio Brbara
Departamento de Biologa Animal, Biologa Vegetal y Ecologa, Facultad de Ciencias, Universidad de A Corua, 15071 A Corua, [email protected], [email protected]
Anales del Jardn Botnico de MadridVol. 63(1): 13-26
January-June 2006ISSN: 0211-1322
Abstract
A revision of the genus Dasya in northwestern Iberian Peninsu-la is presented. Three species (Dasya hutchinsiae, D. ocellataand D. sessilis) are confirmed whilst other three (Dasya corym-bifera, D. punicea and D. rigidula) are excluded from the Gali-cian seaweeds flora. The alien species Dasya sessilis Yamada isa new record for the European Atlantic coasts. The study of theherbarium material reveals that D. sessilis was misidentifiedwith other Dasyaceae species and that it has been collected onthe Galician coasts for more than 16 years. Morphological andanatomical features of D. sessilis as well as its distribution andchronological data on the Galician coasts are provided. A com-parison of the Iberian specimens with the Mediterranean andAsian plants is also included. Dasya sessilis was found growingon a wide range of substrata, from the lower intertidal to sub-tidal at moderate wave-exposed and sheltered areas. It is abun-dant in harbours and aquaculture areas together with otheralien species such as Heterosiphonia japonica and Undaria pin-natifida. The comparative study between D. sessilis and similarEuropean and Iberian Dasyaceae species is undertaken to pre-vent further misidentifications. Dasya sessilis is the largestDasya species, with broader main axes (1-2 mm wide vs 200-500 m in D. ocellata and 500-600 m in D. hutchinsiae);pseudolaterals of D. sessilis are 3-5 times pseudodichotomous-ly branched compared to 5-8 times in D. hutchinsiae and 4-5times in D. ocellata; pseudolateral tips are broader in D. sessilisthan in D. ocellata, but smaller than pseudolateral apices of D. hutchinsiae; tetrasporangial stichidium of Dasya sessilis has6-7 periaxial cells (and 6-7 tetrasporangia) per fertile whorl vs.4-5 in the rest of the native species; and tetrasporangialstichidia of D. sessilis are longer and cystocarps broader thanthose in D. hutchinsiae. The alien Dasyaceae species Heterosi-phonia japonica, similar in size to Dasya sessilis, differs from it inmain axes branching (alternate or distichous in H. japonica vs.spiral in D. sessilis), the number of periaxial cells in the vegeta-tive axes (4 in H. japonica vs. 5 in D. sessilis), and color (pinkishred vs. deep red). Other distinctive characters are the tips ofmain axes (70-90 m wide in H. japonica vs. 100-130 m in
Resumen
Se presenta una revisin del gnero Dasya en el noroeste de laPennsula Ibrica que confirma la presencia de tres especies(Dasya hutchinsiae, D. ocellata y D. sessilis) y excluye la de otrastres (Dasya corymbifera, D. punicea y D. rigidula) de la flora ben-tnica marina gallega. La especie alctona Dasya sessilis Yama-da es nueva para el Atlntico europeo. El estudio de material deherbario revela que D. sessilis ha sido confundida con otras es-pecies de Dasyaceae y que ha sido recolectada en la costa galle-ga desde hace ms de 16 aos. Se presentan las caractersticasmorfolgicas y anatmicas de D. sessilis as como su rango dedistribucin y la cronologa de introduccin en la costa gallega.Asimismo se lleva a cabo la comparacin del material gallego deD. sessilis con especmenes mediterrneos y asiticos. Dasya ses-silis aparece sobre una gran variedad de sustratos, desde el in-termareal inferior a infralitoral, en costas semiexpuestas a prote-gidas. Es adems abundante en zonas portuarias y de cultivosmarinos, donde aparece junto con otras especies introducidastales como Heterosiphonia japonica y Undaria pinnatifida. Conel objetivo de facilitar futuras identificaciones se realiza un estu-dio comparado de D. sessilis y otras especies similares de Dasya-ceae presentes en el Atlntico Ibrico y Europa. Dasya sessilis esla especie de Dasya ms grande, con ejes principales anchos (1-2 mm frente a 200-500 m en D. ocellata y 500-600 m en D.hutchinsiae); pseudolaterales que se ramifican pseudodicotmi-camente cada 3-5 veces frente a 5-8 veces en D. hutchinsiae y 4-5 veces en D. ocellata, y con pices ms anchos que en D. ocel-lata pero ms estrechos que en D. hutchinsiae; estiquidios de lostetrasporocistes con 6-7 clulas periaxiales (y 6-7 tetrasporocis-tes) por segmento frtil frente a 4-5 en el resto de especies deDasya europeas y son ms largos y los cistocarpos ms anchosque los de D. hutchinsiae. Otra Dasyaceae alctona, Heterosi-phonia japonica, tambin alcanza un gran tamao, pero difierede Dasya sessilis en la ramificacin de ejes principales (alterna odstica en H. japonica, helicoidal en D. sessilis), el nmero de c-lulas periaxiales de los ejes vegetativos (4 en H. japonica, 5 en D.sessilis) y el color (rosado rojo frente a rojo oscuro). Otros carac-teres de identificacin de ambas especies son el ancho de los
Introduction
Dasya sessilis Yamada (Dasyaceae, Ceramiales) isan introduced Asian species which has been previous-ly reported from the European coast only in theMediterranean Sea (Verlaque, 2002). It is present inthe sheltered and shallow waters of the Thau Lagoon(France), where it was usually misidentified with oth-er native European species of Dasya, like D. hutchin-siae Harvey. Similar confusions were already pointedout by Yamada (1928), who indicated misidentifica-tions between D. sessilis and D. punicea (Zanardini)Meneghini ex Zanardini on the Japanese coasts. Herewe report the discovery of this taxon for the IberianPeninsula. Although its distribution is likely to bebroader in the NE Atlantic, where it could be morecommon than expected in mariculture and harbourareas, so far it has been only detected in Galicia. Asoccurs with French materials, the Galician popula-tions of D. sessilis were also confounded with otherDasya species, and a study of the herbarium materialreveals a high number of wrong identifications ofDasyaceae species for more than 16 years. In thisstudy we present a morphological and anatomical de-scription of Dasya sessilis, its known distribution andchronological sequence of appearance in the IberianPeninsula. Moreover, we present the comparativestudy between D. sessilis and similar Iberian Da-syaceae species to prevent further misidentifications.According to Brbara & al. (2005), five Dasya speciesare reported for the benthic marine flora of Galicia:D. corymbifera J. Agardh, D. hutchinsiae Harvey inHooker, D. ocellata (Grateloup) Harvey, D. puniceaand D. rigidula (Ktzing) Ardissone. Another alienDasyaceae species common along the Atlantic IberianPeninsula coasts is Heterosiphonia japonica Yendowhich was formerly reported as Dasysiphonia sp.(Brbara & al., 2003). Both alien species are similar inmorphology and frequently occur together in thesame habitats, like aquaculture and harbour areas.
Material and methods
For the morphological and anatomical study weused material of Dasya species and Heterosiphonia
14 V. Pea & I. Brbara
japonica preserved in formaline seawater 4% andherbarium material (see Appendix) deposited in L,SANT, and the private herbaria of Bescansa (ACorua) and Miranda (Santiago de Compostela).
Results and discussion
A. Dasyaceae in northwestern Iberian Peninsula
A.1. Description and reproduction of Dasya sessilis(Figs. 1-3)
Thalli 1-several erect axes, (3)5-25(28) cm high intetrasporophytic plants and (5)6-13(18) cm high ingametophytic plants, terete, attached by a discoid rhi-zoidal holdfast; deep red color. Main axes composedof 5 periaxial cells, spirally branched to 4 orders,densely corticated throughout from apical parts, ta-pering gradually from 1,5-2 mm to 100-130 m. Char-acteristic pseudolaterals 1,5-2 mm long, with (3)4pseudodichotomies at narrow angle every (1)2-3(6)cells, a basal cell unbranched, (65)70-75(80) m long,(40)45-65(75) m wide, apical cells acute, 15-55 mlong, 15-20 m wide. Aborted pseudolaterals usuallythree-celled, frequently with rounded apical cells atbasal part of axes.
Cystocarps sessile, lateral or occasionally subapicalon lateral branches, spirally arranged, urceolate,(650)700-810(850) m long, (480)520-600(650) mwide, with a prominent and flared neck to 250-350m in diameter. Pericarp 3-layered, carpostome(70)80-150(170) m in diameter, carposporangia(30)38-63(70) m long, (13)15-18(20) m wide.
Spermatangial branches (200)300-520(650) mlong, (60)80-100(150) m wide, lanceolate, sessile orborne on a 1-2-celled monosiphonous stalk; fertilesegments (6)7-10(14), spermatangia ellipsoidal, 2-3m in diameter, tips monosiphonous, (6)9-11(12)cells long.
Tetrasporangial stichidia (350)400-900(950) mlong, (100)110-130(150) m wide, with 6-7 periaxialcells, elongate, ovoid to cylindrical and pointing tomonosiphonous tips, sessile or borne on 1-2-celledstalks on monosiphonous branches bases, rarely ter-minal in middle and upper parts of the plant. Cylin-
Anales del Jardn Botnico de Madrid 63(1): 13-26. January-June 2006. ISSN: 0211-1322
D. sessilis), and the diameter of pseudolaterals at the base(broader in H. japonica).
Keywords: Alien species, Ceramiales, Dasya hutchinsiae, Dasyaocellata, Dasya sessilis, Dasyaceae, Galicia, Heterosiphoniajaponica, Iberian Peninsula, Rhodophyta.
pices de ejes principales (70-90 m en H. japonica, 100-130 men D. sessilis) y el dimetro de los pseudolaterales en su parte ba-sal (ms anchos en H. japonica).
Palabras clave: Ceramiales, Dasya hutchinsiae, Dasya ocellata,Dasya sessilis, Dasyaceae, especies alctonas, Galicia, Heterosi-phonia japonica, Pennsula Ibrica, Rhodophyta.
