Phoronis muelleri Selys-Longchamps, 1903

Larva: Actinotrocha branchiata Müller, 1846

° References of the most recent published diagnoses


Last update: June 24, 2004  

Extended specimens up to 120 mm in length, 0.2-1 mm in diameter.
Colour in life: body pink and lophophore transparent, occasionally with spots.
Lophophore horseshoe-shaped with ends sometimes turned medially, but with the tentacles becoming shorter in the middle of the oral side. Number of tentacles up to 100, length 1-2 mm.
Nephridia opening into both oral and anal compartments of metacoelom by a single funnel, with descending and ascending branches ending by the nephridiopore on anal papilla, opening at level of anus.
A single giant nerve fiber on left side, 7-40 µm in diameter; a very thin nerve fiber rarely present on right side.
Left lateral mesentery absent except at level of left nephridium (indicated by a dotted line in the muscle formulae - but herein by the absence of line).
Longitudinal muscle bundles of feathery type; the mean formula and general formula are respectively:

9 | 9
4 | 4
= 26  and  5-13 | 5-12
 2-8 |  2-8
[17-39]   (n= 620 individuals)

Sexual reproduction dioecious; females shed ova freely into the seawater; males have large, glandular lophophoral organs.
Asexual reproduction by transverse fission.

Phoronis muelleri penetrates vertically into muddy to sandy sediments with a high organic content and often with coarse particles of detritus and in the water column suspended material. The vertical distribution extends from the intertidal zone to about 400 m, but is mainly between 10 and 60 m. Densities may reach ca. 3000 ind.m-2. P. muelleri is frequently recorded in Macoma and Amphiura communities.

Phoronis muelleri is a cosmopolitan species: the distribution is represented below on the map.

Type-locality: Helgoland (Germany)

© Christian C. Emig

Last update: May 31, 2019

Distribution of P. muelleri

  •  Most recent published diagnoses
  • Emig C. C., 2019. Phoronida and Brachiopoda in the Indian River (Florida, USA). Nouveaux eCrits scientifiques, NeCs_01-2019, p. 1-10.

  • Emig C. C., Roldán C. & J. M. Viéitez, 2005. Filo Phoronida. In: Fauna Ibérica, vol. 27. Museo de Ciencias Naturales, CSIC Madrid, p. 19-54 & 180-186 & 223-224.

  • Zezina O. N. & S. N. Temereva, 2005. Brachiopoda and Phoronida. In: Biota of the Russian waters of the Sea of Japan, Ed. A. V. Adrianov, vol. 3, 138 p. Dalnauka, Vladivostock.

  • Emig C. C., Çinar M. E. & Z. Ergen, 2003. Phoronida from the Eastern Mediterranean and Black Sea. Cahiers de Biologie Marine, 44 (2), 185-190.

  • Bibliography on Phoronis muelleri