Amathia verticillata ( delle Chiaje, 1822 )

Ruiz-Velasco, Sofía, Ros, Macarena, Guerra-García, José M. & López-Fé, Carlos M., 2025, Fouling bryozoans in recreational marinas of the Canary Islands (North-Eastern Atlantic) with new records of non-indigenous and cryptogenic species, Zootaxa 5656 (1), pp. 1-63 : 45-46

Amathia verticillata ( delle Chiaje, 1822) Introduced

( Fig. 23 )

Hydra verticillata delle Chiaje, 1828: 203, pl. 47, figs 1, 2. Zoobotryon pellucidum : Marcus 1937: 139, pl. 28, fig. 75A, B. Zoobotryon verticillatum : Gordon & Mawatari 1992: 14, fig. 2F; Winston 1995: 88, figs 1B, 2; Abdesalam & Ramadan 2008:

37, fig. 3; Amat & Tempera 2009: 761–764, fig. 1A, B; Farrapeira 2011: 13–16; Minchin 2012: 2146–2150, figs 1, 2; Galil

& Gevili 2014: 1, figs 1, 2; Vieira et al. 2014b: 518, figs 98–101. Amathia verticillata : Waeschenbach et al. (2015): 678; Marchini et al. (2015): 355–362, fig. 2.

Figured material. Pasito Blanco (26/06/23) (1C on floating pontoon).

Other material examined. Garachico (20/06/23) (1C on floating pontoon) ( MNCN 25.03/4471), Morro Jable (27/06/23) (1C on floating pontoon), Corralejo (28/06/23) (1C on buoy).

Description. Erect and uncalcified colonies formed by transparent stolons showing trifurcated branches ( Fig. 23A, B ). Zooids oval present in clusters in both sides of the stolon ( Fig. 23C ). Generally, one long cluster of zooids on both sides of each internode, with the clusters on the end of the branch with a pointy appearance ( Fig. 23D ). Embryos with internal brood.

Remarks. Amathia verticillata is the most common species of this genus in port environments in European waters. Other species included in the genus Amathia recorded in the Canary Islands are Amathia vidovici ( Heller, 1867) and Amathia lendigera ( Linnaeus, 1758) ( Moro et al. 2017) , which can easily be differentiated from A. verticillata by the (1) the branching pattern of the colony (trifurcated only in A. verticillata ), (2) pattern of the zooids (spiral in A. vidovici ), and 3) the disposition of the zooids on the stolon (disposed in two straight lines in A. lendigera ) ( Souto et al. 2010).

Distribution and status. Nascimento et al. (2021) suggested a worldwide introduction of Amathia verticillata , with records in Australasia, the Pacific Ocean, the Indian Ocean, the Mediterranean Sea and the Atlantic Ocean, including Macaronesia (see Nascimento et al. (2021) Supplementary Material 2). It was detected for the first time in the Canary Islands around 2011 ( Olenin & Minchin 2011). The Caribbean has been proposed as the native area of this species due to its occurrence in natural areas and its specific association with the native nudibranch Bermudella zoobotryon ( Smallwood, 1910) ( Galil & Gevili 2014) . Nevertheless, further molecular studies are necessary to confirm this potential origin ( Nascimento et al. 2021). Particularly, in the Canary Islands we consider this species as introduced due to its recent first record in the Canarian archipelago (namely in 2011, by Olenin & Minchin 2011), its association with vessels and other man-made structures ( Minchin 2012), and the fact that it forms massive colonies that can hardly be overlooked.

Figures

FIGURE 23. Amathia verticillata (delle Chiaje, 1822) (MNCN25.03/4471). A. Colonies in vessel hull at Corralejo marina. B. Branching pattern through stereomicroscope. C. D. Close-up of the zooids. Scale bars: B = 600 µm; C, D = 300 µm.