Escharella quadrata, Lopez de la Cuadra & Garcia-Gomez, 2001

López De La Cuadra Car Los G Ar Cía Góm Ez, Los M., 2001, Mediterranean, collected by`Fauna IbeÂrica’ expeditions, Journal of Natural History 35 (11), pp. 1717-1732 : 1718-1720

Escharella quadrata n. sp.

(gure 1A–C, table 1)

Material

HOLOTYPE: M NCN 25.03/1227. A complete colony with ovicells. The ancestrula and rst zooids are overgrown by a polychaete, and are not visible. Coated for SEM. Fauna III sta. 213 A. Punta de’s M urté (N orth of M enorca Island, Baleares ). Trawling from point 40ss4.23¾N, 4ss11.38¾E to point 40ss5.20¾N, 4ss8¾E, 60– 55 m depth, 29 June 1994.

Material examined for comparison. Escharella praealta ( Calvet, 1907) . MNCN 25.03 /3569. Ovicellate colony, coated for SEM. La Atunara ( La Lónea de la Concepción , Cádiz, Straits of Gibraltar), 50 m depth, July 1987 .

Description

Colony encrusting, unilaminar. Zooids oval or polygonal, recumbent, distinctly separated. frontal wall rugose, with one or two rows of small marginal pseudopores. Primary ori ce round, slightly wider than long, with a quadrate lyrula as broad as high (gure 1B, C), although some zooids may have a pointed lyrula. Devoid of condyles, but sometimes with small lateral denticles (gure 1B). There is a distal internal shelf below the operculum, di cult to see from outside (gure 1C). A low peristome bears six oral spines, persisting in ovicellate zooids, and a medial pointed umbo. Ovicell spherical, very prominent, not closed by the operculum. Numerous small basal pore chambers link neighbouring zooids.

Discussion

Three species of Escharella exist in the western Mediterranean with a similar zooidal shape and more than four oral spines in non-ovicellate zooids. The number of spines and the features of the ori ce distinguish Escharella quadrata n. sp. from them. Escharella octodentat a (H incks, 1880) has eight spines in non-ovicellate zooids, six persisting in the presence of an ovicell, and a broad lyrula with lateral spiny projections. Escharella acuta Zabala, Maluquer and Harmelin, 1993 , has six oral spines, but only four persist in ovicellate zooids, and it has a very low and broad concave lyrula ( Zabala et al., 1993). Escharella quadrata n. sp. is externally very similar to Escharella praealta ( Calvet, 1907) (gure 1D –F), a species which has been cited in the Gulf of Cadiz ( Calvet, 1907), the Canary Islands (Aróstegui, 1986) and the Straits of G ibraltar (López de la Cuadra and G arcóa-G ómez, 1988, 1993, 1994). Dr J.-G. Harmelin has sent to the authors photographs of both species found in caves in the Mediterranean French coast. Both have a similar zooidal shape, lack condyles and develop six oral spines which persist in ovicellate zooids. The zooids of E. quadrata n. sp. are remarkably smaller than those of the atlantic examples of E. praealta , which are always longer than 0.6 mm (López de la Cuadra and Garcóa- G ómez, 1993), but in the M editerranean, both species are similar in size (H armelin, personal communication). Escharella praealta has a granular frontal rugosity (gure 1D), diOEerent from the nodular rugosity of E. quadrata n. sp. (gure 1A). Both species diOEer remarkably in the ori ce, which in E. quadrata n. sp. has a quadrate lyrula (gure 1B, C) while in E. praealta it bears a pointed lyrula (gure 1E, F). Escharella quadrata n. sp. has a distal shelf under the operculum, which is di cult to see in external view but is very remarkable when observed from the inner surface (gure 1C). This feature is absent in E. praealta (gure 1F). One of the photographs sent to the authors by J.-G. Harmelin shows one zooid of E. quadrata with a pointed lyrula. The distal shelf is thus more reliable as a distinctive feature. In addition, E. quadrata n. sp. lacks the umbo which grows over the aperture of the ovicell in E. praealta (gure 1D).

Etymology. quadrata refers to the quadrate lyrula.