Reteporella cf. arborea (Jullien, 1882)

Souto, Javier, Berning, Björn & Ostrovsky, Andrew N., 2016, Systematics and diversity of deep-water Cheilostomata (Bryozoa) from Galicia Bank (NE Atlantic), Zootaxa 4067 (4), pp. 401-459 : 451-452

Reteporella cf. arborea (Jullien, 1882)

( Fig. 126 )

cf. Retepora arborea Jullien, 1882: 21 , pl. 16, figs 49, 50. cf. Sertella arborea: Hayward 1979: 67 , fig. 5.

Material examined. MNCN 25.03/3984, locality DR02; MNCN 25.03/3985, locality DR05.

Remarks. Only two small colonies were observed, both comprising the ancestrula and 2–3 autozooids. The main characteristics of these small colonies allow placing the specimens in the genus Reteporella but the absence of important characters of later astogenetic stages prohibits specific assignment and a comprehensive description.

The frontal area of the ancestrula is pyriform, with the broad proximal part occupied by a flat cryptocystal shelf. The distal opesia is rounded, its proximal margin forming a broad and deep, square sinus. The presence of nine mural spines is shared with the ancestrulae of other Reteporella species, whereas the frontal area in those species is oval and lacking a cryptocystal shelf. The early astogenetic autozooids in Reteporella cf. arborea are characterised by the presence of a medial pseudosinus in the proximal peristomial margin, six jointed oral spines and a faintly denticulate distal orificial margin. The frontal shields of the first generations of autozooids display a reticulate pattern of thin but distinct ridges. A similar surface pattern in adult zooids is known only in two nonfenestrate species in the central NE Atlantic, viz Reteporella jullieni Calvet, 1931 from the Azores and Reteporella arborea (Jullien, 1882) from the southern Bay of Biscay and the NW Iberian slope. Whereas the distance to the Azores makes it unlikely that the Galicia Bank specimens are conspecific with R. jullieni , it is very likely that the two young colonies belong to R. arborea (see images in Hayward 1979, fig. 5). The type localities of these species are not too distant from Galicia Bank and their general zooecial morphology corresponds to that in young colonies. While d'Hondt (1974) also reported Reteporella jullieni Calvet, 1931 as occurring in the southern Bay of Biscay (as Sertella jullieni ), these specimens are likely to belong to R. arborea . Both species are in need of revision as SEM images have not been published to date.

The specimens were recovered from two stations at 1099 and 1697 m depth.

Figures

FIGURE 126. Reteporella cf. arborea: ancestrula with distal daughter zooids and two lateral zooidal buds (MNCN 25.03 / 3985).