° References of the most recent publications

Diagnosis

Last update: June 20, 2017   Extended specimens up to about 140 mm, diameter 0.3 to 1 mm. Colour in life: pink-yellowish. Lophophore horseshoe-shaped, ends sometimes turned medially. Up to 140 tentacles, length 2-2.5 mm . Nephridia with two pseudo-funnels, the anal slightly larger than oral, a descending and ascending branch; nephridiopore opens on anal papilla at anus level. A single giant nerve fibre, on the left side at the level of the attachment of the left lateral mesentery to the body wall, 10-20 µm in diameter. Longitudinal muscle bundles of feathery type, developed into six longitudinal zones and circular musculature with three sphincters (see Silén, 1952); the mean formula and general formula are respectively: 5 | 5 4 | 4 = 18  and  4-6 | _5  4-5 | 3-4 [17-19]   (n= 146 individuals) Sexual reproduction: hermaphroditic, ova freely discharged in the sea-water; males with large, glandular lophophoral organs. Phoronis pallida is embedded vertically in soft sediments, generally sand to muddy sand. Santagata (2002) cites a commensalim within the burrow of the thalassinid shrimp Upogebia pugettensis in False Bay (Washington, USA). Temereva & Chichvarkhin (2017) reported two specimens in the burrows of Axiidea shrimp Nihonotrypaea japonica in Vostok Bay (Sea of Japan, Russia) Bathymetric range from the upper subtidal to 60 m. Densities up to 74 000 individuals/ m-2. The distribution of Phoronis pallida is represented below on the map. Type-locality: Gullmar Fiord (Sweden) © Christian C. Emig Last update: June 20, 2017