North-eastern Atlantic and Mediterranean species of Comulariidae Dana, 1846 (anthozoa: Stoloniferal) with the description of a new genus

North-eastern Atlantic and Mediterranean species of Cornulariidae Dana, 1846 (Anthozoa: Stolonifera) with the description of a new genus P.J. López-González, O. Ocaña, J.C. García-Gómez & J. Núñez P.J. López-González; O. Ocaña; J.C. García-Gómez & J. Núnez. North-eastern Atlantic and Mediterranean species of Cornulariidae Dana, 1846 (Anthozoa: Stolonifera) with the description of a new genus. Zool. Med. Leiden 69 (20), 29.xii.1995: 261-272, figs 1-21.— ISSN 0024-0672. P.J. López-González, Departamento de Biología Animal, Vegetal y Ecología, Facultad de Ciencias Experimentales, Universidad de Jaen, Paraje "Las Lagunillas" s/n, 23071 Jaen, Spain. O. Ocaña & J. Núñez, Departamento de Zoología, Facultad de Biología, Universidad de La Laguna, Tenerife (Canary Islands), Spain. J.C. García-Gómez, Laboratorio de Biología Marina, Departamento de Fisiologia y Biología Animal, Facultad de Biología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain. Key words: Anthozoa; Stolonifera; Cornulariidae; Cervera gen. nov. The North-eastern Atlantic and Mediterranean species of the family Cornulariidae are re-examined and taxonomically revised. This family is mainly characterized by the absence of sclerites. Up to now, only one genus, Cornularia Lamarck, 1816, has been assigned to the family. Studies of the internal and external anatomy of the European species of Cornulariidae, carried out for the first time on a comparative basis, leads us to propose a new genus, Cervera. New combinations of the species included in the family are proposed. The main characters of Cervera gen. nov. are the presence of a fine chitinous periderm, various communication canals in the stolons and the absence of a additional chitinous layer that covers the periderm. Cornularia atlantica Johnson, 1861, is described for the first time subsequent to the original description, and is here designated as the type species of the new genus. The taxonomic significance of the anatomical and histological characters in the Cornulariidae are discussed and the systematic position of the species previously attributed to the genus Cornularia is reassessed. Introduction Several revisions of the stoloniferous octocorals have been carried out over the last century (e.g. Hickson, 1894, Gohar, 1940, Weinberg, 1978, and Bayer, 1981). Only one genus, Cornularia Lamarck, 1816, has been included in the family Cornulariidae Dana, 1846. It has been described as lacking sclerites, and having separate polyps united by stolons. In the type species, Cornularia cornucopiae (Pallas, 1766), the stolons have only one canal, a thin periderm and a thick external chitinous cuticle covering the anthosteles and stolons (Benke and Hündgen, 1984). However, several authors (Light, 1915; Utinomi, 1950, 1955; Suzuki, 1971) also included species in the genus having stolons with more than one canal, and the diagnosis of the genus and family were therefore adapted to include these species. In Europe the family Cornulariidae is represented by two species, Cornularia cornucopiae and Cervera atlantica (Johnson, 1861) comb. nov. Cornularia cornucopiae is widely distributed in the western Mediterranean and is also known from the Atlantic coasts of south-western Europe. Cervera atlantica was described from Madeira by Johnson (1861) as Cornularia atlantica, and had not been reported since its original description. This species is redescribed here and assigned to a new genus, together with other, Japanese species. 262 López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) A comparative study of the anatomy of the two European species revealed useful characters for the classification of the family Cornulariidae. Material and Methods Colonies were collected from hard substrata by hand in the intertidal region, and by snorkeling or SCUBA diving in the upper infralittoral area. They were anaesthetised in a saturated solution of sea water and menthol, and preserved in 6-8% formalin. A stereomicroscope was used for external anatomical studies. Histological sections, 8 urn thick, of dissected polyps and stolons were made using the classic method for topographical staining of Cajal (Gabe, 1968). Specimens were deposited in the Nationaal Natuurhistorisch Museum, formerly Rijksmuseum van Natuurlijke Historie (RMNH) of Leiden, the Museo Nacional de Ciências Naturales of Madrid (MNCN), Spain, and the Laboratorio de Biologia Marina (LMB) of the University of Seville, Spain. Descriptive part Order Stolonifera Hickson, 1883 Family Cornulariidae Dana, 1846 Diagnosis.— Colonies small, without sclerites. Polyps not joined in a common coenenchymatous mass, but connected by stolons with one or several internal canals. Anthosteles and stolons covered by a periderm, and sometimes a thick additional cuticle. Type genus: Cornularia Lamarck, 1816. Cornularia Lamarck, 1816 Diagnosis.— Cornulariidae with polyps connected by stolons that are weakly attached to substratum, variable in length, circular in cross-section, and with one internal cavity. Stolons and anthosteles covered by a periderm and by a thick chitinous envelope, forming a kind of theca; anthocodiae retractable into the theca. Type species: Tubularia cornucopiae Pallas, 1766, by monotypy. Cornularia cornucopiae (Pallas, 1766) (figs 1-9) Tubularia cornucopiae Pallas, 1766: 80, fig. 37. Cornularia rugosa Lamarck, 1816:112. Cornularia cornucopiae; Schweigger, 1820: 425; Hickson, 1894: 334. Not Cornularia cornucopiae; Manuel, 1979: 393,1981: 34. For further references, see Weinberg, 1978:141. Material.— RMNH Coel. 23136 (Santa María del Mar, Cadiz, southern Spain, 36°11'N - 6°2'W, interti- López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) 263 dal, 31.Í.1990, 1 fragment); RMNH Coei. 23137 (El Chato, Cadiz, southern Spain, 36°31'N - 6°16'W, intertidal, 9.Ü.1990, 1 colony); RMNH Coel. 23138 (Canos de Meca, Cadiz, southern Spain 36°11'N - 6°2'W, intertidal, ll.ii.1990, 1 colony); RMNH Coel. 23139 (Tarifa, Cadiz, southern Spain, 36o0'48"N - 5°36'W, lim, 9.VÜ.1990, 1 fragment); LBM (Pantalán de San Felipe, La Linea, Cadiz, southern Spain, 36°9'N - 5022'W, 6 m, 26.vii.1990, 2 colonies); LBM (Punta Almina, Ceuta, Spanish city in North Africa, 35°54'N - 5°16'W, 25 m, 13.V.1988, 2 colonies). Morphology (figs 1-2).— Colonies small; polyps connected by stolons of variable length. Stolons circular in cross-section, about 0.2 mm in diameter (range 0.12-0.25 mm), covered by a thick chitinous cuticle that does not strongly adhere to the substratum. Anthostele also covered by a thick envelope. In retracted polyps, the upper part of the thick chitinous cuticle appears to be separated from the polyp (fig. 2). In expanded polyps, the limit of the periderm is visible on the polyp body as a bottleneck (also reported by Benke and Hündgen, 1984) (see white arrows in fig. 1). Tentacles with 14-18 pinnules on each side. Basal junctions of polyps and stolons narrow and of similar diameter as the stolons. Polyps translucently white and the chitinous envelope beige or brown. Distance between polyps variable (1.7-7 mm in the material examined). Height of expanded polyps 6.5-10 mm. Anatomy (figs 3-4).— Retracted polyps elongated (fig. 3). Stolons circular in Fig. 1. Cornularia cornucopiae, general form. Aquarium photograph showing expanded polyps and the limit of the periderm (indicated by white arrows). Scale bar: 2 mm. 264 López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) Fig. 2. Cornularia cornucopiae, general form. Habitus of expanded and retracted polyps and stolons. AC, anthocodia; AT, anthostele; PH, pharynx; RP retracted polyp; ST, stolon; TE, tentacle. Scale bar: 2 mm. cross-section, with only one internal canal of 120-150 urn in diameter (fig. 4). External layer, with concentric grooves, 8-13 urn thick (fig. 5). Adherence of foreign particles to the exterior is minimal. Mesogloea reduced to less than 1 urn in thickness. General aspect and development of ectoderm and endoderm similar. Muscular processes were not observed. Cover of the anthostele varying in thickness from its base (5 urn) to the distal edge of the theca, where it becomes reduced (1 urn) (fig. 6). Ectoderm, mesoglea and endoderm of anthostele and stolon similar in appearance. In the anthocodia the thickness of these three layers is about 10 urn, in the anthostele and stolon about 2 urn. In the anthocodia the ectoderm and endoderm can be thicker than the mesogloea with ectodermal and endodermal muscle processes on mesogloeal arcs. In the tentacles, the thickness of the mesogloea is rather uniform (4- 5 urn) and the longitudinal musculature is better developed than the circular musculature (fig. 7). Pharynx in cross-section irregular in outline. Its mesoglea less than 1 urn thick, its endoderm 20-40 um thick. The single well-defined siphonoglyph appears midway, in the lower part of the pharynx. Mesenteries short, with kidney-shaped filaments and weakly developed muscu- López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) 265 Figs 3-9. Cornularia cornucopiae, anatomical and histological details. Fig. 3. Longitudinal section of a polyp and its stolon. Fig. 4. Cross-section of stolon. Fig. 5. Detail of wall of stolon. Fig. 6. Longitudinal section of a polyp, showing the difference in thickness of the mesogloea in anthostele (bottom) and anthocodia (top). Fig. 7. Cross-section of a tentacle. Fig. 8. Cross-section of a mesentery and retractor muscles. Fig. 9. Transverse section of a mesenteric filament. CC, chitinous cuticle; LM, longitudinal musculature; ME, mesogloea; PO, polyp; RM, retractor musculature; ST, stolon. Scale bars: in fig. 3, 800 urn; in fig. 4,100 urn; in fig. 5,9 pm; in fig. 6, 20 urn; in fig. 7, 35 urn; in fig. 8,20 urn and in fig. 9,40 urn. 266 López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) lature (fig. 9). More distally, the longitudinal musculature of the mesenteries is diffuse (fig. 8). Habitat.— Cornularia cornucopiae occurs in the intertidal and upper infralittoral areas, mainly on sponges, bryozoans, ascidians, hydrozoans and algae. Distribution.— The species has been reported from the western Mediterranean (Stiasny, 1941; Pax & Müller, 1955, 1962; Weinberg, 1978; Bibiloni & Cornet, 1980; Ocharan & Anadón, 1981; Gili, 1982; Roca, 1986) and the Atlantic coasts of France (Teissier, 1965), Portugal (Saldanha, 1974), the Azores (Tixier-Durivault & d'Hondt, 1974) and Astúrias (northern Spain) (Ocharan & Anadon, 1981). Cervera gen. nov. Diagnosis.— Cornulariidae with polyps connected by flattened stolons that are strongly attached to the substratum, variable in length, irregularly elongate in crosssection, and with several internal canals. Anthosteles and stolons covered by a weak periderm only. Type species: Cornularia atlantica Johnson, 1861, designated herein. Etymology.— The name Cervera has been adopted in honour of Mr Joaquin Cervera, recently deceased, who helped us in obtaining financial support and with the organization of marine biological expeditions around the Strait of Gibraltar. The gender of the name is feminine. Cervera atlantica (Johnson, 1861) comb. nov. (figs 10-21) Cornularia atlantica Johnson, 1861: 298. ?Anthelia inermis Berenguier, 1954: 61. ?Cornularia inermis; Roca, 1986: 540. Material.— MNCN 02.04/0003 (Isla de Tarifa, Cadiz, southern Spain, 36°0'48'N - 5°36'W, 2 m, ii.1991, 1 colony); RMNH Coel. 23140 (Santa María del Mar, Cadiz, southern Spain, 36°31'N - 6°17'W, intertidal, 30.ii.1990, some fragments); RMNH Coel. 23141 (Isla de Tarifa, Cadiz southern Spain, 36°0'48MN - 5036'W, 2 m, 6.Ü.1991, 1 colony + 3 fragments); RMNH Coel. 23142 (Ceuta, Spanish city in North Africa, 35°53'N - 5°16'W, 3-5 m, 15.viii.1991, 3 fragments); RMNH Coel. 23143 (idem, 9-12 m, 17.viii.1991,1 colony); RMNH Coel. 23144 (idem, 1 m, 20.viii.1991, 1 fragment); RMNH Coel. 23158 (Candelária, Tenerife, Canary Islands, 28o34*30"N - 16°20*W, 3 m, 4.Ü.1989, 2 colonies); RMNH Coel. 23159 (Punta Hidalgo, Tenerife, Canary Islands, 28°21'N - 16°22'W, 1 m, 9.iii.l990, 2 colonies); RMNH Coel. 23160 (Montana Roja, La Tejita, Tenerife, Canary Islands, 28°30'N - 16°33'W, intertidal, under stones, 20.Í.1990, 2 colonies). Morphology (figs 10-11).— Colonies small; polyps up to 1 cm in height, connected by flattened stolons of variable length, and maximally 2-3 mm in width. Polyps translucently orange. Anthosteles (represented by the basalmost 2-3 mm of the polyps) and stolons covered by a thin brownish periderm. Junctions of polyps and stolons wide. Tentacles with 12-14 pinnules on each side. Anatomy (figs 12-21).— Retracted polyps conical or spherical (fig. 12). Outline of stolons irregularly elongate in cross-section. Each stolon containing 3-5 principal canals and others smaller in size (fig. 17-18). Foreign particles adhering to external Lopez-Gonzalez et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) 268 López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) Figs. 12-21. Cervera atlantica, anatomical and histological details. Fig. 12. Longitudinal section of a retracted polyp and its stolon. Figs 13-14. Details of wall of polyp, showing the mesogloeal lacunae and the weak chitinous cuticle. Fig. 15. Transverse section of anthocodia, showing the well-developed endoderm. Fig. 16. Detail of transverse section of a tentacle, displaying a thick mesogloea and the longitudinal musculature. Fig. 17-18. Cross-section of stolon, showing the mesogloeal canals. Fig. 19. Transverse section through a mesentery. Fig. 20. Oocyte. Fig. 21. Packet of spermatogonia. CA, canal; CC, chitinous cuticle; EN, endoderm; LM, longitudinal musculature; ME, mesogloea; ML, mesogleal lacunae; OV, oocyte; PO, polyp; RM, retractor muscle; SP, packet of spermatogonia; ST, stolon. Scale bars: in fig. 12,1 mm; in figs 13-14, 25 urn; in fig. 15, 37 urn; in fig. 16,15 urn; in figs 17-18, 360 pm; in fig. 19, 50 pm; in fig. 20, 35 urn and in fig. 21, 65 urn. López-González et al. Species of Cornulariidae. Zool. Med. Leiden 69 (1995) 269 surface of periderm. Ectoderm scarcely developed. Mesogloea with a complex system of lacunae, lined with thin (5 um) endoderm. Periderm of anthosteles similar to that of stolons. Ectoderm scarcely developed. Mesoglea well-defined, reaching its maximal thickness in the anthostele. Large lacunae filled with cells present in mesogloea of both anthosteles and stolons (figs 13-14). Endoderm of anthosteles weakly developed, reaching its maximal development distally in the anthocodia (fig. 15). Ectoderm of tentacles and pinnules well developed, 10-12 urn thick; longitudinal musculature strong, supported by mesogloeal processes, up to 10 urn thick in the pinnules and axis of the tentacles. Circular musculature present but not well marked. Endoderm well developed, 4-5 urn thick (fig. 16). Mesenteries with a thin mesoglea and weak musculature (fig. 19). The colony fragments from Santa María del Mar (Cadiz) (RMNH Coel. 23140) collected in February 1990, contain oocytes up to 69 urn in diameter (fig. 20). The colony from Tarifa (MNCN 02.04/0003) collected in February 1991, contains well developed packets of spermatogonia, up to 205 urn in diameter (fig. 21). In the pharynx, the mesoglea is reduced in thickness to 5 urn. Ectoderm welldeveloped, about 45 pm thick. Siphonoglyph distinct, with mesogloeal lacunae at its more proximal level; its cilia moderately long. Habitat.— The specimens were collected under stones, in rock fissures and caves in intertidal and upper infralittoral areas. Distribution.— So far, Cervera atlantica had only been reported from Madeira (Johnson, 1861). The present records extend the area of distribution to Tenerife (Canary Islands) and the Strait of Gibraltar. Discussion Three species to be accommodated in Cornulariidae have been reported from European waters, including the Azores, Canary Islands and Madeira, viz., Cornularia cornucopiae (Pallas, 1766), Cervera atlantica (Johnson, 1861) and "Anthelia" inermis Berenguier, 1954. The last-named species is still insufficiently described and a careful anatomical study is in fact necessary to establish whether it is different from Cervera atlantica (see below). Cornularia cornucopiae is a well known European species (see distribution) and needs no further discussion by itself. Cervera atlantica (Johnson, 1861) was originally described from Madeira as Cornularia atlantica. Johnson's brief description of this species reads as follows: "Basal band narrow, [...], destitute of spicula, but invested by a thin epidermis containing particles of sand; when retracted, forming a fleshy hemispherical button". The characters mentioned in this description justify its inclusion in Cornulariidae, but do not match Cornularia cornucopiae. In Cornularia cornucopiae, the thicker translucent chitinous envelope of the anthostele forms a theca. In fully retracted polyps the distal part of this theca is empty (fig. 2), an aspect well illustrated by Weinberg (1978). This theca is absent in Cervera. Another difference exists in the junction of polyp and stolon. In Cornularia cornucopiae this junction is narrow, while it is wide in Cervera atlantica. The last-named species had not been reported again since its original description. Our