Cylindrolepas sinica Ren, 1980

Hayashi, Ryota, 2013, Intraspecific variation in the turtle barnacle, Cylindrolepas sinica Ren, 1980 (Cirripedia, Thoracica, Coronuloidea), with brief notes on habitat selectivity, ZooKeys 327, pp. 35-42 : 36-39

Cylindrolepas sinica Ren, 1980 Figs 1, 2

Cylindrolepas sinica Ren, 1980: 194, fig. 6; pl. 2 figs 12-20. Hayashi 2009: 1, fig. 1A, B. Hayashi 2012: 118, figs 10, 15g, pl. 3d.

Platylepas decorata Zardus & Balazs, 2007: 1303, figs 7-9. Frick and Zardus 2010: 294.

Material examined.

From the plastron of a green sea turtle stranded on Ishigaki Island, Okinawa, Japan, November 25, 2001, Ryota Hayashi coll. (RUMF-ZC-02047); from the plastron of a living green sea turtle, April 17, 2004, Hahajima Island, Ogasawara, Tokyo, Japan, Ryota Hayashi coll. (RUMF-ZC-02045); from a plastic tag on a stranded loggerhead sea turtle, September 26, 2010 at Yomitan, Okinawa, Japan, Ryota Hayashi coll. (RUMF-ZC-02048).

Additional description of intraspecific variation in the parietal wall.

Wall outline stellate, parietes concave (Fig. 1C); translucent between external ornamentation, external longitudinal ridges low, broad, poorly defined, growth ridges numerous, fine, closely spaced; (Fig. 1D); sutural elaborations opaque, erect, irregular ridges slightly directed toward apex, not cupped (Fig. 1E); radii very narrow, externally teeth partly concealed by sutural elaborations (Fig. 1F); internal midrib broad, short, flaring terminally or club-shaped, directed more downward than medially (Fig. 1G); internal lateral ribs well developed, moderately broad, short, extending below the basal margin, approximately same size and number of ribs on each side of midrib on all plates (Fig. 1 G–H); sheath about two-thirds height of wall, basally terminating abruptly, not depending (Fig. 1D). Opercular valves and soft parts as described in Ren (1980) and Hayashi (2012).

Remarks.

The original description of Cylindrolepas sinica described the rounded, cylindrical form and is accurate for individuals occurring on the soft skin of sea turtles. The general morphology of this species is as described by Ren (1980) and Hayashi (2012) and illustrated in the present work in Figs 1A, 1B, and 2A. Frick and Zardus (2010) and Frick (2013) regarded Cylindrolepas sinica as a junior synonym of Platylepas decorata Darwin, 1854. However, morphological differences between Cylindrolepas sinica and Platylepas decorata are clearly detailed by Monroe and Limpus (1979), Ren (1980), Young (1991), and Hayashi (2012). Cylindrolepas sinica can be distinguished fromother species easily by the morphological characteristics listed in Table 1. In addition, the mitochondrial sequence variation of this and related species has been confirmed (the 12S rRNA, tRNA-Val and 16S rRNA regions, Table 2, see Appendix). Therefore, Cylindrolepas sinica is a valid species. In the phylogenetic analysis of Hayashi et al. (2013), Cylindrolepas sinica clustered with the whale barnacles ( Xenobalanus , Coronula , and Cryptolepas ). The pseudo-stalked barnacle Xenobalanus globicipitis also has hexagonal and cylindrical shell walls (Fig. 1 A–I). Comparing these findings, Cylindrolepas sinica is likely ancestral to the whale barnacles ( Hayashiet al. 2013).