Megabalanus tintinnabulum (Linnaeus, 1758)

Pochai, Ashitapol, Kingtong, Sutin, Sukparangsi, Woranop & Khachonpisitsak, Salinee, 2017, The diversity of acorn barnacles (Cirripedia, Balanomorpha) across Thailand's coasts: The Andaman Sea and the Gulf of Thailand, Zoosystematics and Evolution 93 (1), pp. 13-34 : 22-24

Megabalanus tintinnabulum (Linnaeus, 1758) Figure 11 ; Tables 2, 3

Lepas tintinnabulum Linnaeus, 1758: 668.

Balanus tintinnabulum : Bruguiére 1789: 165 (in part); Holthuis and Heerebout 1972: 24, pl.1.

Lepas tintinnabulum Wood, 1815: 38, pl. 6, figs. 1, 2.

Balanus tintinnabulum tintinnabulum : Pilsbry 1916: 55, pl. 10, fig. 1-1e; Hiro 1939: 258, figs. 7a-b; Daniel 1956: 17, pl. 4, figs. 1-6; Davadie 1963: 26, pl.2, fig. 4, pl. 6, figs. 1a, 2b; Zevina and Tarasov 1963: 87, fig. 8; Stubbings 1964: 335.

Balanus tintinnabulum var. tintinnabulum : Oliveira 1941: 11, text-fig. 1, pl. 2, figs. 1, 2, pl. 4, fig. 1, pl. 5 fig. 3, pl. 8, fig. 6.

Megabalanus tintinnabulum : Newman and Ross 1976: 68; Lacombe and Rangel 1978: 3, fig. 4.

Non-type material examined.

Andaman Sea: 3 specimens, Phang-nga province , Takua Thung district, Na Tai beach, 16.V.2015, A. Pochai (BUU16.BN.MT01-03) .

Description.

Peduncle absent; base calcareous. Shell cylindric or conic with 6 plates (1 carina, 2 carinal latus, 2 latus, 1 rostrum); parietes reddish to brownish red usually with longitudinal striations on external surface, parietes not prominently ribbed and rather smooth, irregular shape of parietal tubes (parietes tubiferous), sutural edges of radii with regular denticles, radii wide with horizontally striated, radii tubiferous; internal surface of parietes pale-purple with horizontal greyish violet striations around aperture. Orifice subcircular to rhombus. External surface of operculum white-pale pink and orange with prominent growth ridges in both tergums and scutums, internal surface of operculum white. Scutum bigger than tergum, scutum triangular, adductor ridge of scutum prominent; tergum with spur, spur furrow of tergum closed, scutal margin denticulate.

Distribution.

Megabalanus tintinnabulum is widely distributed across almost all continents and is a well-known cosmopolitan fouling species. It was previously found in French Guiana, the United States, Australia, Mexico, Ecuador, Kuwait, Saudi Arabia, Sweden, France, Netherlands, Singapore, Indonesia and India ( Henry and Mclaughlin 1986; Thiyagarajan et al. 1997; Jones et al. 2000; Jones 2004). Similar to Amphibalanus , it is considered as an introduced species in several regions and its distribution has been facilitated via shipping ( Jones 2004). In Thailand, Megabalanus tintinnabulum specifically occurs in the low shores at Na Tai beach, Phang-nga province (the Andaman Sea). However, it does not appear to be a common fouling species as seen in some regions. Megabalanus tintinnabulum might have been introduced to Phang-nga beaches via ship transport, and the competition for habitat niche is compromised, compared to previously occupying cosmopolitan Amphibalanus amphitrite .

Remarks.

Megabalanus tintinnabulum has relatively larger shell plates than those of Amphibalanus . All three examined species ( Megabalanus tintinnabulum , Amphibalanus amphitrite and Amphibalanus reticulatus ) in family Balanidae have opercular valves with prominent growth ridges horizontally, and tergum with a clear spur. The coloration among these three species is easily distinguishable, in that purplish longitudinal striations presenting Amphibalanus amphitrite , vertical and longitudinal red-orange striations with orange-pale pink background presenting Amphibalanus reticulatus and brownish red surface with some irregular and unclear longitudinal stripes presenting Megabalanus tintinnabulum .

Figures

Figure 11. Megabalanus tintinnabulum collected from Na Tai beach, Phang-nga (BUU 16. BN. MT 01). A. Dorsal and ventral view of external shell, B. External (left panel) and internal (right panel) view of tergum (upper panel) and scutum (lower panel), C. External (upper panel) and internal (lower panel) view of shell plates. Abbreviations: c, carina; cl, carinal latus; l, latus; r, rostrum.