Amphibalanus amphitrite (Darwin, 1854)

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 : 20-21

Amphibalanus amphitrite (Darwin, 1854) Figure 9 ; Tables 2, 3

Balanus amphitrite var. communis Darwin, 1854: 240 (in part).

Balanus amphitrite Weltner, 1897: 264; Pilsbry 1907: 190; 1928: 312.

Balanus amphitrite communis : Hiro 1939: 263.

Balanus amphitrite hawaiiensis : Hiro 1939: 260.

Amphibalanus amphitrite : Pitombo 2004: 263.

Non-type material examined.

Andaman Sea: 2 specimens, Phang-nga province , Khura Buri district, Ao Khoei beach, 30.VII.2015, A. Pochai (BUU16.BN.AA01-02) . 4 specimens, Phang-nga province , Takua Thung district, Na Tai beach, 16.V.2015, A. Pochai (BUU16.BN.AA03-06) . 4 specimens, Phuket province, Mueang Phuket district, Ao Yon beach, 15.VII.2015, A. Pochai (BUU16.BN.AA07-10) . 3 specimens, Phuket province, Mueang Phuket district, Panwa beach, 16.VII.2015, S. Khachonpisitsak (BUU16.BN.AA11-13) . 4 specimens, Phuket province, Katu district, Kalim beach, 15.VII.2015, A. Pochai (BUU16.BN.AA14-17) .

Gulf of Thailand: 2 specimens, Nakhon Si Thammarat province, Sichon district, Hin Ngam beach, 09.VIII.2015, A. Pochai (BUU16.BN.AA18-19) . 4 specimens, Prachuap Khiri Khan province, Bang Saphan district, Ban Krut beach, 06.IX.2015, A. Pochai (BUU16.BN.AA20-23) . 2 specimens, Chon Buri province, Ko Si Chang district, Ko Kham Yai beach, 05.VII.2015, S. Khachonpisitsak (BUU16.BN.AA24-25) . 4 specimens, Chon Buri province, Si Racha district, Si Racha beach, 04.VII.2015, A. Pochai (BUU16.BN.AA26-29) . 3 specimens, Chon Buri province, Mueang Chon Buri district, Khao Sam Muk beach, 05.VII.2015, A. Pochai (BUU16.BN.AA30-32) .

Description.

Peduncle absent; base calcareous. Shell white-pale pink with 6 plates (1 carina, 2 carinal latus, 2 latus, 1 rostrum); single rows of parietal tubes (parietes single tubiferous) with transverse septa; radii solid. External surface with purple longitudinal striations from apex to base (3-4 lines per plate) without horizontal striation, transverse teeth on suture edges with denticles on lower regions, internal surface of parietes grey with black horizontal striations close to operculum. External surface of operculum brownish grey, internal surface of operculum grey-white. Scutum bigger than tergum, scutum triangular, external surface of scutum with curved striations; tergum spur board with growth lines.

Distribution.

Amphibalanus amphitrite is a common fouling barnacle and cosmopolitan species distributed along intertidal zones of coastlines in both the Gulf of Thailand and the Andaman Sea. It was found in all stations examined. The settlement patterns are various (e.g. rocks, shells of oyster and green mussels, concrete walls of bridges and harbors, offshore vessels, dock pilling, and mooring robes). In previous records, this species distributes worldwide in both tropical and temperate regions including the Indo-West Pacific, and Western Australia ( Jones 2004; Chen et al. 2014) and it has been suggested that this wide range of distribution was due to human-mediated activities during global trade expansion ( Chen et al. 2014).

Remark.

The morphology of Amphibalanus amphitrite is variable from diverse habitats worldwide. Shells exposed and eroded by heavy wave action showed no purple stripes on the external surface. The molecular analysis has confirmed its genetic differentiation which might be due to local adaptation and geographical isolation ( Chen et al. 2014). Due to hypothesis on human-mediated activities as the main cause of Amphibalanus amphitrite 's distribution across the globe, this species is considered as non-native or introduced species in these examined regions: Hawaii, California, North Carolina, and the Atlantic coast ( Carlton et al. 2011), whereas it is considered as native in tropical waters (e.g. Hong Kong, Thailand, Malaysia) supported by molecular study ( Chen et al. 2014). Despite the diverse morphology of Amphibalanus amphitrite , another species in the same genus Amphibalanus reticulatus exhibits clear patterns of shell carrying both vertical and longitudinal striations on the external surface. The separation of settlement type is distinct between these two species; one is found mostly on rocky shores exposed to waves and the other one is found on some mollusk shells.

Figures

Figure 9. Amphibalanus amphitrite collected from Khao Sam Muk beach, Chon Buri (BUU 16. BA. AA 30). 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.