Canda ligata ( Jullien, 1882 ) Jullien, 1882

Souto, Javier, Reverter-Gil, Oscar & Fernández-Pulpeiro, Eugenio, 2011, Redescription of some bryozoan species originally described by J. Jullien from Iberian waters, Zootaxa 2827, pp. 31-53 : 32-34

Canda ligata ( Jullien, 1882) comb. nov.

( Figs 1–6 ; Table 1)

Caberea ligata Jullien, 1882: 518 , pl. 16, figs 51–54; Calvet 1907: 378; Prenant & Bobin 1966: 455, fig. 150 I–IV; d’Hondt 1974: 46, fig. 5.

Material examined. Lectotype (designated here): NHMUK 1899.7.1.883, Caberea ligata (Busk Coll.) , Amphiphelia, Cotes d’Espagne, Ocean Atlantique. Paralectotype (designated here): MNHN 2532, Travailleur Dr. 42, 44°01'20'' N, 9°25'00'' W, 896 m, 16/8/1881. Other material examined: MNHN 6933, Thalassa T511, 44º02.0’ N, 7º02.0’ W, 750 m; MNHN 7200, Thalassa Y 415, 40º34.4’ N, 9º22.6’ W, 450 m; MNHN 7207, Thalassa Y 415, 40º34.4’ N, 9º22.6’ W, 450 m; MNHN 7174, Thalassa W446, 44º12.8’ N, 8º40.0’ W, 620– 650 m.

Description. Colony erect, jointed, dichotomously branched, anchored to substratum by tubular rhizoids. Branches with two alternating series of autozooids, their frontal planes nearly perpendicular to each other. Dorsal plane of branch formed by basal walls of two series of autozooids. A central autozooid in the bifurcation, flanked by two lateral autozooids facing outwards, and two distolateral facing inwards. Branching initially externally unjointed; jointing subsequently developing fairly soon afterwards, with fractures in calcification revealing internal chitinous joints.

Autozooids elongate, subrectangular, rounded distally, truncate proximally. Frontal surface convex; gymnocyst smooth and imperforate, well developed proximally and laterally. Zooidal opesia occupied by oval membranous wall, surrounded by a slightly prominent rim. Cryptocyst developed proximally, occupying about one quarter to one third of area; diminishing laterally, reaching distolateral corners of area adjacent to bases of a pair of long, slen- der spines, poorly developed or broken in material examined; between them, distal opesial rim projects slightly upwards and distally. Cryptocyst covered by parallel rows of rounded granules.

Scutum about midway along opesial margin, often broken in material examined; lanceolate, with shape of curved kukri knife, overarching opesia and concealing little of it.

Vibraculum at proximal end of each autozooid on basal wall, its setal groove long, slightly curved, angled approximately 45º from branch axis; seta long, smooth, flattened, slightly wider in distal half. Proximal end of vibraculum crossing interzooidal suture, reaching proximal autozooid. A small membrane-covered oval chamber proximally; just proximal to it, a rounded orifice produces a rhizoid or a calcified curved tube joining second or third autozooids of two branches in a dichotomy. Distal end of vibraculum visible in frontal view as lateral projection with U-shaped notch. In frontal view the axial autozooid in a bifurcation seeming to present a pair of distolateral vibracula, these actually corresponding to the vibracula of distolateral autozooids. Avicularia absent.

Ovicell hyperstomial, elongate, frontally flattened, curving towards branch axis, occupying proximal gymnocyst of distal autozooid. Ectooecium smooth, with rounded to drop-shaped frontal fenestra; entooecium finely granular; the pair of lateral-oral spines retained.

Mean SD Minimum Maximum N Autozooid length 0.513 0.0491 0.450 0.581 10 Autozooid width 0.204 0.0373 0.148 0.253 10 Opesia length 0.249 0.0546 0.186 0.341 10 Opesia width 0.108 0.0085 0.100 0.127 10

SD, Standard deviation; N, number of measurements.

Remarks. Caberea ligata was originally based on three samples collected at 896 m depth northwest of the Iberian Peninsula and a badly preserved specimen from 2018 m depth on Galicia Bank. Calvet (1907) reported material from more than 2300 m at Cape Verde. Today, only two samples remain, one in the MNHN and the other in the NHMUK, which we have chosen here as lectotype and paralectotype of C. ligata . The species was not reported again until it was mentioned by d’Hondt (1974), collected off Aveiro ( Portugal) 450 m depth. A colony mixed with Jubella enucleata Jullien, 1882 has also been found, collected 620–650 m depth by the Thalassa northwest of the Iberian Peninsula. Subsequently, the species was cited by d’Hondt (1975) as occurring at 76–105 m depth at the Azores, but marked with “?” and lacking further information. As far as we know, there are no further reports of this species.

Since Jullien’s original description was incomplete, Calvet (1907) partially redescribed the species, including the ovicell, which Jullien stated was unknown; in fact, it was depicted in one of his original figures ( Jullien 1882, pl. 16, fig. 53) but none has been conserved in the original material that remains.

Calvet (1907) already noted the similarity between C. ligata , Canda simplex Busk, 1884 and Caberea retiformis Smitt (sic); the latter is now also placed in Canda . This genus is very similar to Caberea Lamouroux, 1816 ; according to Tilbrook (2006) both share similar colonial morphology, autozooids and avicularia. Their main difference seems to be in the development of the vibracula. In Caberea these cover most of the basal surface of the branch and present an elongated and oblique setal groove (not visible in frontal view) with a long, barbed seta. In Canda , the vibracula are shorter and do not cover the basal surface of the branch, but are expanded laterally so as to be partly visible in frontal view. The setal groove is angled approximately 45º from the branch axis, and the seta is not barbed. Significantly, species of Canda typically have calcified connexions between their branches, which is not the case in Caberea .

The characters of C. ligata place it in the genus Canda . This genus is especially represented in the Indo-Pacific region ( Bock 2007). It was revised by d’Hondt (1988), who redescribed its type species, Canda filifera Lamarck, 1816 , from the original sample and material collected in the Red Sea. He included a tabular key for the identification of the Recent species; additional data can also be found in Winston (2005) and Tilbrook (2006). Canda ligata comb. nov. differs from all of them by its oval opesia, the shape of the scutum, the morphology of the gymnocyst and the absence of avicularia.

The genus Canda has previously been reported in Europe only as fossil. Miocene Canda rectangulata Udin, 1964 , found in Austria and Tunisia, seems to differ from C. ligata in its rectangular autozooids lacking a scutum, although the original description and illustration do not allow good characterization of the species.

Canda ligata is a deep-water species, known from off the northwestern Iberian Peninsula between 450–896 m depth. A colony collected from Galicia Bank at more than 2000 m depth was dead and eroded, possibly by transpoartion, but the species is also known from 2300 m at Cape Verde.

Figures

FIGURES 1 – 6. Canda ligata (Jullien, 1882) comb. nov. 1, Jointed dichotomy, showing a rhizoidal connexion between the branches (MNHN 7174); 2, unjointed dichotomy, showing a rhizoidal connexion between the branches (NHMUK 1899.7. 1.883, lectotype); 3, unjointed dichotomy showing two vibracula distal to the central zooid (MNHN 7174); 4, dorsal side of a branch with vibracula (MNHN 7174); 5, an autozooid with scutum (MNHN 7174); 6, two ovicells (MNHN 7174).