Orbinia papillosa (Ehlers, 1907)

Figures 19, 20

Aricia papillosa Ehlers, 1907: 16, figs.7–14.

Orbinia papillosa: Day 1977: 233 .

Material examined. New Zealand: South Island, Christchurch, Heathcote Estuary, Banks Peninsula, 43°32’S, 172°42’E, 22.10.1961, coll. I. Estcourt, AM W.7459, 1 complete specimen .

Type locality. Waiheke, Auckland, New Zealand .

Description. Thoracic width 2 mm. Body long, thorax slightly flattened, abdomen cylindrical, thoracic chaetigers numbering 27 (Fig. 19A). Prostomium conical, short and wide, with sharply pointed tip (Fig. 19C, D). Branchiae from chaetiger 5, triangular with filiform tips; in abdomen becoming long, strap-like with tapering tips, longer than notopodia (Figs 19C, D, G, 20 A–C). Thoracic notopodial postchaetal lobes developed from first chaetiger, digitate, in abdomen becoming wider and lanceolate (Figs 19C, D, G, 20 A–C). Thoracic neuropodial postchaetal lobes as ridges with papillae: chaetigers 1–4 with one papilla, chaetigers 5–6 with 2 papillae, then their number increasing up to 10–12 podal papillae (Figs 19D, E, 20A). Subpodal papillae from chaetiger 20 to 33; on chaetigers 22–29 extending ventrally to near mid-ventral line (Fig. 19A, E, F). Maximum number of foot and subpodal papillae combined per segment about 35. Abdominal neuropodia bilobed with outer lobe longer than inner lobe; subpodal flange well developed, with cirriform flange papillae (ventral cirrus) and scalloped margin (Figs 19B, G, H, 20B, C). Interramal cirrus short, knob-like, not always well marked (Figs 19G, H, 20B, C). Pygidium with two long thin anal cirri (Fig. 19B). Notopodial chaetae crenulate capillaries, in abdominal notopodia also forked chaetae present (Fig. 20B). Thoracic neuropodia bearing 3–4 rows of curved to almost straight smooth uncini and few thin capillaries in upper part of posterior row (Figs 19D, 20A). Abdominal neuropodia with capillary and flail chaetae (Fig. 20B). Both rami supported by thin aciculae in abdomen (Fig. 20B, C).

Distribution. Australia, Victoria, New Zealand.

Habitat. Intertidal, sand, seagrass.

Remarks. Orbinia papillosa was described from New Zealand (Ehlers 1907) and later recorded from Victoria by Day (1977). The specimen studied here is in agreement with the original description. The short knob-like interramal cirrus is reported for the first time for this species.