Prionospio ehlersi Fauvel, 1928: 10 –11, fig. 1; Day 1967: 490, fig. 18.9; Mackie & Hartley 1990: 364 –366, fig. 1. Prionospio (Prionospio) ehlersi: Blake & Kudenov 1978: 217, fig. 20; Maciolek 1985: 345 –347, fig. 7; Imajima 1990 a: 106 –111, figs. 2–3; Blake 1996: 133 –136, fig.4.13.
Material examined. ESFM –POL/05– 1636, 1 specimen, 27 September 2005, Antalya Bay, D 39, 36 º 48 ΄ 49 ʺN, 30 º 37 ΄ 57 ʺE, 100 m, mud; ESFM –POL/05– 1852, 6 specimens, 30 September 2005, Finike Bay, G 18, 36 º 16 ΄ 31 ΄΄N, 30 º 10 ΄ 50 ΄΄E, 75 m, mud; ESFM –POL/05– 3209, 7 specimens, 30 September 2005, Finike Bay, G 19, 36 º 16 ΄0 6 ΄΄N, 30 º 11 ΄ 31 ΄΄E, 100 m, mud; ESFM –POL/05– 3210, 2 specimens, 6 October 2005, Fethiye Bay, G 30, 36 º 39 ΄ 24 ΄΄N, 29 º04΄ 44 ΄΄E, 50 m, sandy mud; ESFM –POL/05– 1997, 18 specimens, 6 October 2005, Fethiye Bay, G 31, 36 º 38 ΄ 56 ΄΄N, 29 º03΄ 38 ΄΄E, 75 m, muddy sand with gravel; ESFM –POL/05– 2600, 26 specimens, 6 October 2005, Fethiye Bay, G 33, 36 º 38 ΄ 28 ΄΄N, 29 º02΄ 37 ΄΄E, 200 m, mud; ESFM –POL/05– 3211, 2 specimens, 6 October 2005, Fethiye Bay, G 32, 36 º 38 ΄ 42 ΄΄N, 29 º03΄ 18 ΄΄E, 100 m, mud.
Diagnosis. Largest specimen incomplete, 0.8 mm wide, 13.6 mm long, with 40 chaetigers. Color in alcohol opaque white. Prostomium anteriorly rounded; laterally somewhat convex; dorsal caruncle extending to chaetiger 2. Two pairs of eyes in trapezoidal arrangement; anterior pair smaller than posterior pair. Branchiae numbering four pairs; first pair longest, with digitiform pinnules; branchiae on chaetigers 3 and 4 apinnate, longer than notopodial lamellae, with dense lateral ciliation and naked tips; branchiae on chaetiger 5 apinnate, longer than those on chaetigers 3 and 4, reaching to chaetiger 7, basally united by a low membrane. Lamellae on chaetiger 1 small, rounded; well developed on following chaetigers. Neuropodial lamella rounded on chaetiger 2, angular, dorsally directed on chaetiger 3; becoming rounded thereafter. Notopodial lamella subtriangular, erected on chaetigers 2–5; becoming smaller, rounded thereafter. Low dorsal crests across dorsum, from chaetiger 6 to 24 – 26. Interparapodial pouches from chaetiger 4 to 19 – 20. Ventral sabre chaeta first present on chaetigers 18–20, numbering 1–2 per fascicle. Multidentate hooded hooks first appearing on neuropodia of chaetigers 19–20 and on notopodia of chaetigers 31–32.
Remarks. The Mediterranean specimens agree with the original and subsequent descriptions of the species (Fauvel 1928, Mackie & Hartley 1990, Maciolek 1985, Imajima 1990 a, Blake 1996). However, notopodial hooded hooks first appeared on chaetigers 31–32 in the Mediterranean specimens; on chaetigers 37 or later in the Atlantic and Pacific specimens (Maciolek 1985); on chaetigers 44–48 in the Japanese specimens (Imajima 1990 a); and on chaetigers 44–60 in the North Atlantic specimens (Blake, 1996).
Ecology. The maximum population density (260 individuals.m - 2) of this species was found on muddy substratum at 200 m depth at station G 33 (Fethiye Bay).
Distribution. Atlantic Ocean, Pacific Ocean, Mediterranean Sea, Red Sea (Tebble 1959; Laubier 1965; Amoureux et al. 1978; Blake 1983, 1996; Maciolek 1985; Imajima 1990 a); 5–4176 m.