Arbocuspis ramosa ( Osburn, 1940 ) Osburn, 1940

Vieira, Leandro M., Almeida, Ana C. S. & Winston, Judith E., 2016, Taxonomy of intertidal cheilostome Bryozoa of Maceió, northeastern Brazil. Part 1: Suborders Inovicellina, Malacostegina and Thalamoporellina, Zootaxa 4097 (1), pp. 59-83 : 74-75

Arbocuspis ramosa ( Osburn, 1940) n. comb.

( Figs. 28–31 )

Electra bellula: Marcus, 1937: 37 (in part), pl. 6, figs. 14A, E–F [not pl. 6, figs. 14B–D]. [ Brazil: São Paulo] Non Membranipora bellula Hincks, 1881: 149 . [ Australia]

Electra bellula var. ramosa: Osburn, 1940: 355 , pl. 2, figs. 20–21. [ Puerto Rico] Electra bellula: Marcus, 1941: 16 (in part), fig. 6 (in part). [ Brazil: Paraná]

Electra bellula: Vieira et al., 2008: 12 (in part). [ Brazil: São Paulo and Paraná]

Material examined. Syntypes: USNM 11826, USNM 11881, Electra bellula var. ramosa , balsam slide with erect and encrusting colony, R. Osburn collection, Piles of Guayanilla, Puerto Rico, Station 2632. Additional specimens: UFPE 0 37, Sobral sewer outfall, Maceió, Alagoas State, Brazil, 9º40'45" S, 35º45'01" W, intertidal, on algae, coll. 27 April 2006 by L.M. Vieira and M.D. Correia; UFPE 0 38, UFPE 0 78, coll. 18 January 2007 by L.M. Vieira and M.D. Correia.

Description. Colony primarily encrusting, multiserial, forming yellowish-white unilaminar to bilaminar plates; erect phases branching, jointed at the base. Encrusting phase with elongate zooids, 0.296–0.445 mm (0.382 ± 0.044) long and 0.148–0.222 mm (0.181 ± 0.018) wide; a distal oval opesia, 0.124–0.235 mm (0.174 ± 0.029) long, is surrounded by a crenulated rim of gymnocyst that occupies one-third to two-thirds of the zooid length, 0.086–0.296 mm (0.213 ± 0.06) long; cryptocyst occurs as a proximal narrower shelf on inner margin of gymnocyst; a pair of curving pointed spines occurs at the distal end of the opesia on either side of the operculum; usually a large median spine, curved, unbranched, is placed very close to the proximal rim of the opesia; one or two smaller lateral spines may occur close to the rim of the opesia. Erect phase branched, formed by two zooids placed back to back, usually followed by four in the next series, forming narrow 4-sided branches; zooids pyriform, with the distal oval opesia and proximal gymnocyst occupying about half of the zooid length; cryptocyst narrow. A pair of pointed spines occurs at the distal end of the opesia on either side of the operculum (but belongs to the distal zooids); a long pointed median spine, unbranched, is placed very close to the proximal rim of the opesia, forming an angle of 60 degrees in relation to the frontal surface; two smaller lateral spines, usually forming a right angle, are placed very close to the proximal rim of the opesia. Colonies develop from a single ancestrula.

Remarks. Despite the absence of branched spines, Electra bellula var. ramosa Osburn, 1940 is here assigned to Arbocuspis owing to the presence of smooth gymnocyst, narrow cryptocyst, and spines slightly bending across the opesia. Arbocuspis ramosa is characterized by a two-phased colony; encrusting and erect colonies have one to three unbranched spines placed at the proximal end of the gymnocyst very close to the opesia and a crenulated opesia rim. It is distinguished from other species of the genus in having only unbranched spines.

Distribution. Arbocuspis ramosa is found in the Western Atlantic, from Puerto Rico to southern Brazil. This is the first record of the species in Alagoas.

Figures

FIGURES 28 – 31. Arbocuspis ramosa, UFPE 0 78, Sobral, Maceió, Alagoas, Brazil; 28, group of zooids of one encrusting colony; 29, lateral view of the zooids of an encrusting colony; 30, two erect branches arising from an encrusting colony; 31, close-up of the autozooids of an erect branch.