Ecteinascidia thurstoni Herdman 1890

(figure 8)

Ecteinascidia thurstoni Herdman, 1890: 151; 1906: 299; Sluiter, 1905; 100; Kott, 1985: 99; Monniot and Monniot, 1997: 1630; not Monniot, 1997b: 567 (< E.rubricollis).

Distribution. The species is recorded from Gulf of Aden (Sluiter, 1905); Gulf of Suez, Gulf of Arabia (Monniot and Monniot, 1997); South Africa (Monniot and Monniot, 1997); Sri Lanka (Herdman, 1906); Western Australia (Kendrew I., WAM Z11786; Cockburn Sound, Kott, 1985).

Remarks. The Western Australian colonies (Kott, 1985) resemble other Indian Ocean specimens in most significant characters, namely course of the gut, gonads in the gut loop with the ovary in the centre of a circle of small male follicles, a similar branchial sac, limited siphonal musculature and similar zooid shape, with sessile apertures on the anterior end.

The difference in the course of the gut in Western Australian specimens (Kott, 1985) and western Indian Ocean specimens referred to by Monniot and Monniot (1997) is not apparent. The one or two anterior muscles from the vicinity of the endostyle that pass across the dorsal surface in front of the base of the atrial siphon (see Sluiter, 1905; Herdman, 1906) were overlooked by Kott (1985), although, on re-examination of the specimens (WAM Z11785, WAM 11.75), these muscles were found to be present. Ecteinascidia thurstoni: Monniot, 1997b has more numerous muscles in this position than the present species and is not conspecific (probably, with E. styeloides: Monniot, 1997b from the same location, being specimens of E. rubricollis). Ecteinascidia thurstoni: Monniot and Monniot, 1997 from the Arabian Gulf, with relatively few muscle bands passing in front of the atrial siphon, appears to be correctly assigned.