Rhynchozoon detectum Harmer, 1957

Martino, Emanuela Di & Taylor, Paul D., 2018, Early Pleistocene and Holocene bryozoans from Indonesia, Zootaxa 4419 (1), pp. 1-70 : 54-56

Rhynchozoon detectum Harmer, 1957

( Figs 160–163 ; Table 36)

Rhynchozoon detectum Harmer, 1957: 1067 , pl. 65, figs 20–24. Figured material. RGM.1350590, Holocene, UPGG041, off South Sulawesi.

Description. Colony encrusting, multiserial, uni- or multilaminar. Autozooids distinct only at growing edge or in new, frontally budded laminae, irregularly arranged, hexagonal, longer than wide (mean L/W = 1.42). Frontal shield convex, nodular, imperforate apart from a few small, 15–25 µm long, oval to subcircular marginal pores. Orifice deep, subcircular, about 95 µm long by 90 µm wide, with a finely denticulate anter, a broadly concave proximal margin, and inconspicuous condyles. Oral spine bases absent. Peristome encircling the orifice and in some zooids developing two cylindrical knob-like processes proximolaterally. Suboral avicularium placed proximolaterally, distolaterally directed, large with a hooked rostrum. Frontal avicularia numerous, either small (about 65 µm long by 40 µm wide), rarely elliptical, commonly pear-shaped, or large (about 100–120 µm long by 45–50 µm wide) and rounded triangular with curved rostrum. Interzooidal avicularia large, with curved, truncated rostrum. All types of avicularia have complete pivotal bars. Ovicells large, globular, broader than long, deeply embedded in the peristome, with extensive exposure of the flattened, smooth to slightly nodular endooecium.

Remarks. Six colony fragments of Rhynchozoon detectum were found in our samples. This species was previously recorded from the Celebes Sea, off Ambon Island ( Indonesia) and Lifu Island (Loyalty Islands, New Caledonia), and Torres Strait, at 0–80 m depth ( Harmer 1957).

N, Number of colonies and number of zooids measured; SD, standard deviation; Av, avicularium; Int, interzooidal.

Figures

FIGURES 160–163. Rhynchozoon detectum Harmer, 1957, RGM.1350590, Holocene, UPGG041, off South Sulawesi. 160. General view of a colony fragment. 161. Close-up of zooids at the colony growing edge. 162. Group of ovicellate zooids with numerous frontal avicularia and a few interzooidal avicularia. 163. Close-up of an orifice, ooecium, hooked suboral avicularium, interzooidal avicularium with truncated curved tip, and small frontal avicularia. Scale bars: Fig. 160 = 500 µm; Fig. 161 = 100 µm; Fig. 162 = 200 µm; Fig. 163 = 50 µm.