Lissoclinum timorense

Lissoclinum timorense (Sluiter, 1909)

Didemnum timorensis Sluiter, 1909

Didemnum voeltzkowi Michaelsen, 1920

Lissoclinum timorensis (Sluiter, 1909)

Lissoclinum voeltzkowi (Michaelsen, 1920)

Specimens examined.

NMNS-7027-005, NMNS-7027-006, ZRC-TUN-0003, ZRC-TUN-0006 and ZRC-TUN-0017 (Pulau Semakau, subtidal at depth 0.5 m)

Colonies are irregularly shaped sheets about 2-5 mm thick (Fig. 2L). The colonies are green due to Prochloron cells distributed in the common cloacal cavities, while the colonial margin and bottom are white due to the dense distribution of stellate and globular spicules. In the five zooids we examined, the thorax had four stigmatal rows: there were seven stigmata in the first row (top), eight in the second row, seven in the third row, and five or six in the fourth row (bottom) (Fig. 2M). Gonads are not found in the present specimens. There are globular spicules in the tunic (Fig. 2N). The presence of stellate spicules easily distinguishes the present species from Lissoclinum bistratum, which lacks these spicules. However, Monniot and Monniot (2001) proposed to regard Lissoclinum timorense as a junior synonym of Lissoclinum bistratum, because the two species differ only in the shape of spicules and there are no distinctive features in the zooids and larvae. The phylogenetic trees established using the partial sequences of cytochrome oxidase subunit I gene did not discriminate the two species, which are distinguished only by the spicule shapes (Hirose et al. 2010).