Fouling bryozoans in Argentine harbours (Southwest Atlantic): new records and the description of a new species Author López-Gappa, Juan Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) & Museo Argentino de Ciencias Naturales (MACN), Av. Ángel Gallardo 470, C 1405 DJR, Ciudad Autónoma de Buenos Aires, Argentina. Author Liuzzi, María G. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) & Museo Argentino de Ciencias Naturales (MACN), Av. Ángel Gallardo 470, C 1405 DJR, Ciudad Autónoma de Buenos Aires, Argentina. Author Castro, Karen L. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) & Grupo de Ecología en Ambientes Costeros (GEAC, IBIOMAR-CONICET), Bvd. Brown 2915, Puerto Madryn, U 91220 ACD, Chubut, Argentina. Author Bobinac, Magalí Dirección de Protección Ambiental (DPAM), Prefectura Naval Argentina, Av. Eduardo Madero 235, C 1106 ACC, Ciudad Autónoma de Buenos Aires, Argentina. & Instituto Universitario de Seguridad Marítima (IUSM), Prefectura Naval Argentina, Corrientes 180, Olivos, Buenos Aires, Argentina. Author Schwindt, Evangelina Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) & Grupo de Ecología en Ambientes Costeros (GEAC, IBIOMAR-CONICET), Bvd. Brown 2915, Puerto Madryn, U 91220 ACD, Chubut, Argentina. text Zootaxa 2022 2022-11-09 5205 4 374 400 journal article 182818 10.11646/zootaxa.5205.4.4 6376a622-e6fd-471b-a545-ce0ede9d2991 1175-5326 7307128 29F8684D-2052-4C52-8578-D06DBD9D361A Bicellariella edentata Marcus, 1955 ( Figs 17–20 ) Bicellariella ciliata : Marcus 1937: 65 , pl. 14, fig. 33. Bicellariella sp. : Hastings 1943: 396 , fig. 27A. Bicellariella ciliata f. edentata Marcus 1955: 292 , fig. 45. Bicellariella edentata : Vieira et al. 2008: 16 . Material examined. MACN-In 11771, Belgrano harbour, 1920. MACN-In 32310, Rawson, February 8, 1977 . MACN-In 32367, Mar del Plata, February, 1983. MACN-In 43870, Ingeniero White harbour, June 22, 2016 , collected by Sandra Fiori. Description. Colony erect, branching, flexible, attached to the substratum by rhizoids which issue from the basal surface of the autozooids. Branches biserial, bending frontally towards their extremity.Autozooids alternating, long, with contiguous proximal regions; distal regions flaring and curving outwards. Autozooid base forked, separated from the middle portion by a constriction; middle portion slender, in turn separated from the flaring distal portion by a second constriction. Frontal membrane oval, oblique, occupying the terminal third of the autozooid, with a distal, C-shaped operculum, bearing a single median proximal spine, and a row of usually four long, curved oral spines along the distal margin. Median zooid at a branch bifurcation bearing three spines, one median distal, and one on each side of the proximal end of the opesia. Axillary zooid bearing only one distal and one inner spine. Avicularia pedunculate, shaped like a bird’s head, attached to the outer side of the autozooid, proximal to the frontal membrane; rostrum with a sharply curved tip, distal outer margin concave, inner margin straight to slightly undulating; mandible triangular, with a pointed, downcurved tip. Ovicell subglobular, prominent, at right angle to the branch axis, attached to the inner edge of the opesia by a short peduncle, with the opening facing the frontal membrane. Ancestrula and first autozooids erect, funnel-shaped, with a terminal circular membrane surrounded by delicate, curved spines. Remarks. As noticed by Marcus (1955) , B. edentata differs from B. ciliata in the shape of the bird’s-head avicularium. While in the European B. ciliata the rostral margin is heavily serrated (see De Blauwe 2009 , fig. 239), it was described as smooth in the Brazilian species B. edentata ( Marcus 1955 ) , and has just a slight undulating margin in the present material ( Fig. 20 ). The smooth beak of the avicularium was also recognized by Hastings (1943) in her R.S.S. ‘William Scoresby’ material from Station WS776 ( 46º18′15″ S , 65º02′15″ W , off San Jorge Gulf). Distribution. Brazil ( Marcus 1937 , 1955 ; Vieira et al. 2008 ), Buenos Aires and Chubut provinces (this study). Its presence in several localities off Buenos Aires and Chubut provinces suggests that this is a warm-temperate native species that reaches its southern limit of distribution in Patagonia ( Hastings 1943 ).