Scrupocellaria

Tilbrook, Kevin J. & Vieira, Leandro M., 2012, Scrupocellaria (Bryozoa: Cheilostomata) from the Queensland coast, with the description of three new species, Zootaxa 3528, pp. 29-48 : 30

Genus Scrupocellaria van Beneden, 1845

Van Beneden, 1845: 26. Harmer 1926: 364 (cum syn.). Liu 1991: 69.

Liu et al. 2001: 492. Tilbrook 2006: 57.

Type species. Sertularia scruposa Linnaeus, 1758 .

Diagnosis. Colony erect, bushy or repent, branching, unilaminar, attached to substratum by rhizoids. Rhizoids originate from either a septular pore or a vibracular chamber. Branches biserial, with alternating zooids, a third (axial) autozooid interpolated at bifurcations, which are produced at regular intervals, each new branch jointed at its inception. Autozooids with membranous frontal area, generally oval and overarched by a scutum (scutal spine) which originates from the inner (branch midline) lateral opesial margin; well-developed gymnocyst, and minimal to well-developed cryptocyst. Avicularia of two kinds: laterally as angular prominences, between the orifice and the vibracular chamber; frontally on the proximal gymnocyst. Vibracula occur basolaterally, associated with each autozooid, and in the axis of each branch bifurcation, on the axial autozooid. Ovicells are hyperstomial, smooth, with pores or a fenestra, or without either. Ancestrula vase-like, anchored to the substratum by rhizoids.

Remarks. Scrupocellaria van Beneden, 1845 was introduced monotypically for Sertularia scruposa Linnaeus, 1758 . The genus now comprises about 88 species ( Bock 2011) from tropical to temperate waters around the world. At least three species have been accorded a widespread distribution, namely S. bertholletii ( Audouin, 1826) , S. delilii ( Audouin, 1826) , and S. maderensis Busk, 1860 , but neither morphological nor genetic studies have been carried out to compare the different populations or explain the morphological variations noted in these taxa. However, ongoing research by the present authors has found that material assigned to each of these three species hides a complex of morphologically similar yet geographically limited species and that the genus itself has a recently unrealised high diversity with many new species awaiting description (Vieira, pers. obs.).

Harmer (1923) distinguished the ‘cellularine’ bryozoans (taxa with erect colonies and a membranous frontal wall) by autozooid position and branching pattern and, for all taxa of Candidae , the position of the chitinous joints distal to branch bifurcations. In Scrupocellaria , the two inner zooids at the bifurcation (F and G zooids: Harmer 1923) are in contact on the basal side of the axial zooid (E zooid) and are shorter than the outer zooids at the bifurcation (C and D zooids). The joints pass near the proximal end of the gymnocyst in the F and G zooids and more distally in the C and D zooids, across or below the opesia. These joint characteristics are important in distinguishing Scrupocellaria from the closely related genus Tricellaria Fleming, 1828 , itself characterised by joints at the proximal end of both the inner and outer zooids at the bifurcation.

Scrupocellaria species all share the characteristic branching pattern noted by Harmer (1923). The species are, however, differentiated using characters such as: scutal morphology (spine-like to broadly oval), position of scutal insertion (just below inner proximal spine to almost proximal to inner edge of the opesia), presence/absence of axial vibracula (zero to two) and ovicell morphology (imperforate, perforate, or with a single fenestra).

Recently a new subgenus, Retiscrupocellaria d’Hondt, 1988 , was erected to accommodate Scrupocellaria jolloisii ( Audouin, 1826) . D’Hondt (1988) based his taxon on differences in colony morphology, such as the presence of branches joined by anastomosing tubes, like those in species of Canda Lamouroux, 1816 . However, until the relationships between the different genera of Candidae have been investigated and a complete revision of Scrupocellaria species attempted, we will follow the diagnostic characteristics of branching pattern (sensu Harmer 1923) and assign the new taxa to Scrupocellaria auctorum .