Ascorhiza mawatarii d’Hondt, 1983

Ramalho, Laís V., López-Fé, Carlos M., Mateo-Ramírez, Angel & Rueda, José Luis, 2020, Bryozoa from deep-sea habitats of the northern Gulf of Cádiz (Northeastern Atlantic), Zootaxa 4768 (4), pp. 451-478 : 455-462

Ascorhiza mawatarii d’Hondt, 1983

( Figs 2 A–E; 3A)

Ascorhiza mawatarii d’Hondt, 1983: 24 , fig. 12; Harmelin & d’Hondt 1992b: 609.

Material examined. MNCN 25.03 /4194: DA10, Gazul MV, 390–410 m depth, 26 June 2010 , INDEMARES CHI- CA project, Instituto Español de Oceanografia ( IEO) coll., on shells ; MNCN 25.03 /4195: BT05, Chica MVD, 607–665 m depth, 19 February 2011 , INDEMARES CHICA project, IEO coll., on shells.

Description. Colony erect (22–42 mm long), delicate, formed by a dilated head (7–18 mm long x 3.5–6 mm wide) and a narrower peduncle (15–24 mm long x 1–1.5 mm wide) ( Fig. 2A, B ), fixed to the substrate directly by expansion of the peduncle base or by rhizoids ( Fig. 2C ). Zooids from the head disposed irregularly, hexagonal with circular aperture ( Fig. 2D ); zooids from de peduncle (myoecia) with distinct form: those near the top polygonal, alternately arranged ( Fig 2E ), those near the base somewhat rectangular, slightly longer than wide, arranged in rows ( Fig. 3A ).

Remarks. There are two described species of Ascorhiza : A. mawatari and A. occidentalis Fewkes, 1889 ( Bock 2019; accessed 02.12.2019). The latter species is characterized by a narrow stalk composed of a number of segments, externally indicated by ferrules of uniform size with well-marked indentations. Ascorhiza mawatari was described from the Northern Pacific Ocean ( d’Hondt 1983) and recorded later by Harmelin & d’Hondt (1992b) in European waters, precisely in the GoC and in the Mediterranean Sea (Bouche des Bonifacio). Colony length in the original material is 20 mm (peduncle: 12 mm long by 1.8 mm wide; head: 4.5 mm wide), while the material described by Harmelin & d’Hondt (1992b) from the GoC is more similar to our specimens (up to 55 mm long). The present material differs from that described by previous authors in having a narrower peduncle (often 1 mm wide) and smaller zooids (both length and width): d’Hondt (1983) reported that myoecia were almost 1 mm long by 0.4–0.5 mm width. Although the GoC material was poorly preserved, as all the peduncles were collapsed, the general features were similar. Two attachment modes were observed associated to the different type of substrate. In colonies attached to shells, the base was continuous and expanded, while colonies attached to sand grains used several rizhoids ( Fig. 2C ). Apparently, this species varies in both the base of the peduncle and the shape of the peduncle zooids, and further studies are required to understand the reasons behind this variability, as the knowledge on this species is still scarce.

Habitat and associated species. Ascorhiza mawatari was found associated with the bathyal cold-water coral framework (mainly Madrepora oculata Linnaeus ), colonized by small gorgonians ( Acanthogorgia and Bebryce ). It was also found in sand and muddy sea bottoms with sea pens [ Kophobelemnon stelliferum (Müller) and Funiculina quadrangularis (Pallas) ], solitary corals (e.g. Flabellum chunii Marenzeller ) and sea urchins, mainly Cidaris cidaris (Linnaeus) .

Figures

FIGURE 2. Ascorhiza mawatari d’Hondt, 1983 (MNCN 25.03/4195). A. General view of some colonies. B. General view of a colony (SEM). C. Detail of the fixation mode: left, expanded base of the peduncle on a shell; right, base of the peduncle with several rizhoids. D. Detail of the head showing the circular aperture. E. Detail of the zooids forming the top of the peduncle.

FIGURE 3. A. Ascorhiza mawatari d’Hondt, 1983 (MNCN 25.03/4195), detail of the zooids which compose the base of the peduncle. B–D. Antropora gemarita Ramalho & López-Fé n. sp. (MNCN 25.03/4197). B. General view of a colony fragment. C. Detail of the colony showing one complete zooid with cryptocyst and interzooidal avicularia. D. Ovicellate zooid.