Austromegabalanus psittacus, (Molina, 1782)

Hosie, Andrew & Ahyong, Shane T., 2008, First records of the giant barnacles, Austromegabalanus nigrescens (Lamarck, 1818) and A. psittacus (Molina, 1782) (Cirripedia: Balanidae) from New Zealand, with a key to New Zealand Balanidae, Zootaxa 1674, pp. 59-64 : 60-62

Austromegabalaus psittacus ( Molina, 1782)

( Fig. 1 , 2 F–J)

Material examined. NIWA 25576, 9 specimens, Waterloo Quay, Port Wellington, New Zealand, 41°16.911’S, 174°46.840’E, about 10 m, coll. D. Morissey et al., 22 Feb 2006; NIWA 25444, 11 specimens, Coquimbo, Chile, 29°57.19’S, 71°21.78’W coll. N. Bruce & M. Thiel, 25 Jul 2006.

Remarks. The present specimens of A. psittacus represent not only the first record of the species from New Zealand, but also the first extralimital record of the species.

Austromegabalanus psittacus is the largest known sessile barnacle, attaining a height of 20 cm and width of 8 cm, and ranges along much of the Pacific coast of South America, ranging from Peru to Chile and to Patagonia in the Atlantic ( Young 2000). Within its natural range, A. psittacus inhabits a wide range of substrates, from the shore to at least 20 m. In Chile, A. psittacus is a culinary delicacy and in 1996, over 870 tonnes were commercially harvested ( FAO 2006).

The material of A. psittacus from Port Wellington comprises a single cluster of nine individuals, the largest with a maximum height of 53.9 mm and a maximum carino-rostral diameter of 18.6 mm ( Figure 2 F–J). The Port Wellington specimens of A. psittacus agree well with Chilean material (NIWA 25444), differing in having proportionally longer and more slender tergal apices. The differences in the tergal apices are probably attributable to wear and damage—the Port Wellington specimens were growing on a level subtidal substrate without intense wave action, in contrast to the Chilean specimens from intertidal rocks on an open coast. The similar size of most Port Wellington A. psittacus suggests that they recruited at a similar time, perhaps even via a single reproductive event from a source population attached to a vessel hull.

Figures

FIGURE 1. Native distribution of Austromegabalanus nigrescens (grey) and A. psittacus (black). Inset: Known New

FIGURE 2. A – E, Austromegabalanus nigrescens, Taharoa Terminal, NIWA 34692. A. psittacus, Wellington Harbour, NIWA 25576. F – J, A, F, overall cluster. B, G, tergum, internal aspect. C, H, tergum, external aspect. D, I, scutum, internal aspect. E, J, scutum, external aspect. Scale A – E = 10 mm, F – J = 5 mm.