Rhabdopleura striata Schepotieff, 1909 (Fig. 4E, F)

Type locality. Kankesanturai, northern Sri Lanka, 2‒3 m depth on hardstone .

Key features. Inception of ringed erect tubes is indirect. The type colony was described as 7‒8 cm long, with erect-tube height 11‒12 mm and diameter 1 mm; the zooid is 1.0‒ 1.5 mm long and yellowish with pigment spots. Creeping tubes are almost straight, with few blind-ending lateral branches, all (with few exceptions) along one side only; these are proximally adherent for 2‒3 mm before rising perpendicularly. Unique to R. striata is a wedge or web of cuticle, with fusellar sutures, in the angles where lateral branches diverge from the creeping tube (Fig. 4F). Fusellar collars are weakly developed, “so that at low magnification the living tubes appear clearly longitudinally striped [i.e. having aligned vertical fusellar striae], but not transversely ringed” [“so dass bei schwacher Vergrösserung die Wohnröhren deutlich längsgestreift, nicht aber quergeringelt erscheinen” (Schepotieff 1909, p. 431)]. There are 8‒10 ‘panels’ in each fusellar ‘circle’ [between fusellar collars]. The number of ‘circles’ varies from 150 to 500 depending on tube length. Fusellar height is 100‒125 μm.

Comment. Rhabdopleura striata is exceptional for its large tubes and zooids, with aligned longitudinal striae in ‘panels’ within the fusellae. Furthermore, in contradistinction to R. normani and similar species with indirectly budded erect tubes, side branches issue almost exclusively from just one side of the creeping tube.