Turbicellepora robusta ( Barroso, 1921 )

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 : 1724-1727

Turbicellepora robusta ( Barroso, 1921)

(gure 3A–D, table 3)

Lekythopora robusta Barroso, 1921: 76 , gure 6.

`Schismopora ’ robusta : G aut ier, 1962: 263.

Turbicellepora robusta : d’H ondt, 1979: 458.

Material

Twenty-on e colonies from F auna IV stations 275, 277, 281 and 290 (Columbretes Islands, July 1996), all of them small (less than 5 mm) and epibiotic on substrata already living or of living origin: hydroid stems, colonies of the bryozoan Margaretta cereoides (Ellis and Solander) and algae. F igured for this work: MNCN 25.03 /3567, sta. 275, 39ss53.88¾N, 0ss41.33¾E; Puerto To ño, Columbretes, 30 m depth (gure 3C, D); M N CN 25.03 /3568, sta. 290, 39ss50.86¾N, 0ss40.60¾E; Islote Baleato, Columbretes, 15 m depth (gure 3A, B) .

Material of Turbicellepora torquata Hayward, 1998 observed for comparison: holotype, The Natural History Museum , London, reg. no. 1976.7.14.1. Bay of Naples, 30 August 1958 .

Description

Colony encrusting to nodular, small. Zooids oval, adnate at the rst layer if there is a surface to grow (on foliose algae, for instance), but usually erect and closely packed. Frontal wall very rugose, with nodules and longitudinal ridges. Ori ce round, slightly longer than wide, with a small U-shaped sinus and lateral condyles. In fresh material, the sinus and condyles as a whole may produce the optical eOEect of a deep V-shaped sinus. A well-developed peristome surrounds the ori ce, and often extends on to the ovicell. The peristome often has an irregular border, with extensions and denticles; it is very open, not obscuring the ori ce as a rule. Each zooid bears a columnar avicularium, usually low, very often remaining within the peristome, although it may also grow upwards, never very high. The avicularium is ogival, approximately twice longer than wide, with an elongate pointed rostrum and mandible, proximolateral to the ori ce and directed laterally upwards. A second peristomial avicularium has been observed exceptionally. There are no vicarious avicularia with diOEerent morpho logy, but very rarely an avicularium similar to the peristomial type develops vicariously. Ovicell spherical, with about 10 round pseudopores, open to the peristome and usually overgrown by the peristome. The ancestrula could not be observed because it was always overgrown by later zooids.

Discussion

Turbicellepora robusta ( Barroso, 1921) is inmediately distinguishable from all other Atlanto-mediterranean species of Turbicellepora by its remarkably rugose frontal wall, even in young zooids. It seems that the species lacks large vicarious avicularia as they are not present in 21 colonies found, from young to senescent. In only two colonies, some vicarious avicularia, similar to the peristomial type, are inserted between zooids (gure 3D), but they are very inconspicuous. Another very distinctive character of T. robusta is the peristome, which is high and equally developed all around the ori ce, growing over the ovicellular ori ce and very often enclosing the columnar avicularium within it (gure 3A). The ogival elongate avicularium (gure 3B) and the ori ce with a very well-de ned U-shaped sinus which is clearly separated from the condyles (gure 3C) are also distinctive features.

After Hayward (1978), two boreoarctic species, Turbicellepora canaliculata ( Busk, 1884) and Turbicellepora nodulosa ( Lorenz, 1886) , grow as small nodules on erect living substrata and lack large vicarious avicularia. Both have smooth frontal walls and are very unlikely to be present at the Mediterranean. In addition, the oral avicularium of T. canaliculata has a very tall and rising cystid, and T. nodulosa has a low peristome and an ori ce with a broad sinus, in contrast with the well-developed peristome but low avicularian cystid and the narrow sinus of T. robusta . Colony size and shape and the substrate preference of T. robusta resemble those of the M editerranean species Turbicellepora torquata H ayward, 1978, examined for comparison (gure 3E, F), but T. torquata has a smooth frontal wall and vicarious avicularia (gure 3E) while T. robusta has a very remarkable rugose frontal wall and lacks vicarious avicularia. In addition, the columnar avicularium of T. torquata is elliptical, not pointed and proportionally smaller than that of T. robusta , and its cystid is produced in a pointed umbo, which is lacking in T. robusta . The ori ce of T. torquata does not have a well-de ned sinus but instead just a V-shaped space between the condyles, appearing like a true sinus (gure 3F). On the contrary, the ori ce of T. robusta is very remarkable in its well-de ned sinus, independent of the space between condyles (gure 3C). The peristomes are also diOEerent. That of T. torquata is more developed proximally than distally and does not overgrow the ovicell, while the peristome of T. robusta is equally developed all around the ori ce and usually overgrows the ovicell (gure 3A), which is for this reason less conspicuously prominent in T. robusta than in most species of the genus.

Barroso (1921) described Lekythopora robusta from a single colony found at Valencia (eastern Spanish coast) encrusting an alga. Although the type material seems to be lost, the description and pictures by Barroso (1921) are unambiguous in the nodulated frontal wall, shape and position of the avicularia and the peristome growing over the ovicell. The sinus of the ori ce was described as V-shaped, a mistake due to its aspect under optical microscopy, but the clear separation between sinus and condyles was also pictured.

Gautier (1962) reported Turbicellepora robusta (as `Schismopora’ robusta ) from the Tunisian coast. D’Hondt (1979) correctly transferred Lekythopora robusta to the genus Turbicellepora in the context of a checklist of Bryozoa from eastern Spain in which a number of species previously cited in several works by Barroso were included, but it is clearly expressed in the work that new material of T. robusta was not found. It is quite common around the Columbretes Islands on living substrata, particularly algae, erect Bryozoa and hydroid stems.