Bicrisia

Bicrisia sp.

(Fig. 3, A–C)

Material examined. SMF 15000, SO 167 Stn 92, 24.15700° S – 24.15350° S, 176.87333° W – 176.87667° W, South Tonga Arc, 673–788 m, collected 31 October 2002. Not bleached.

Description. Colony erect, articulated, branching, incomplete, comprising only 2 fragments c. 4 mm long (Fig. 3, A). Branches biserial, internodes flat, lensoidal in cross section, straight to slightly curved, composed of 3–5 autozooids (Fig. 3, B). Autozooidal orifices circular, alternating, short tubular peristome curved towards frontal side (Fig. 3, C). Lateral to orifice, often a short process with a single spine (Fig. 3, C). Surface regularly perforated by tiny slit-like pseudopores. Gonozooids not observed.

Measurements.

Basal angle 26–41°, σ = 5.6°, N = 5

Length to second zooid 529–589 µm, σ = 28 µm, N = 5

Branch width 123–228 µm, σ = 39 µm, N = 5

Peristome diameter 57–75 µm, σ = 5 µm, N = 15.

Remarks. Measurements were made according to Harmelin (1990). The brood chamber, a feature typically used to distinguish crisiids, is missing. The material is assigned to Bicrisia because of the short internodes and jointed spines in some autozooids, making it different from Crisia, which has no spines in most species.