Laonice bahusiensis, Soderstrom, 1920

Sikorski, Andrey V., Radashevsky, Vasily I., Castelli, Alberto, Pavlova, Lyudmila V., Nygren, Arne, Malyar, Vasily V., Borisova, Polina B., Mikac, Barbara, Rousou, Maria, Martin, Daniel, Gil, João, Pacciardi, Lorenzo & Langeneck, Joachim, 2021, Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species, Zootaxa 4996 (2), pp. 253-283 : 261

Key to the species of the Laonice bahusiensis complex from North European and Mediterranean waters

1 Dorsal crests present on several posterior chaetigers with nuchal organs. Branchiae usually absent on chaetigers posterior to nuchal organs (-5 ≤ Br-NO ≤ 1). Distinct staining with methylene green usually absent on anterior part of prostomium.... 2

- Dorsal crests absent on chaetigers with nuchal organs. Branchiae usually present on up to 12 chaetigers posterior to nuchal organs (-2 ≤ Br-NO ≤ 12). Narrow transverse band intensely stained with methylene green along anterior edge of prostomium and peristomium..................................................................................... 3

2(1) Median eyes very large, occupying entire posterior part of prostomium until occipital antenna. Ratio of length of prostomium in front of median eyes (l 1) to length of median eyes (l 2) less than 2.3. Acute peaks on upper tips of notopodial postchaetal lamellae from chaetigers 5–6 to chaetigers 8–9, if present, not terminal but shifted onto lateral margin. Prostomium not stained with methylene green.................................................................... L. mediterranea n. sp.

- Median eyes moderately large, leaving a free space between the posterior border of the eyes and the occipital antenna equivalent to the length of the eyes. Ratio of length of prostomium in front of median eyes (l 1) to length of median eyes (l 2) always more than 2.5. Acute peaks on upper tips of notopodial postchaetal lamellae of ten anterior chaetigers terminal. Diffuse, indistinct staining with methylene green occasionally present on prostomium............................. L. irinae n. sp.

3(1) Branchiae up to twice as long as notopodial postchaetal lamellae, present to chaetiger 36. 0 ≤ Br-NO ≤ 10. Posterior end of caruncle distinctly visible. Dorsal crests on posterior branchiate chaetigers single. Upper tips of notopodial postchaetal lamellae with an acute peak on at least anterior half of branchiate chaetigers. Adults up to 1.2 mm wide............. L. bahusiensis

- Branchiae slightly longer than notopodial postchaetal lamellae, present to chaetiger 45. 2 ≤ Br-NO ≤ 12. Posterior end of car- uncle usually levelled and indistinct (especially in smaller individuals). Dorsal crests on posterior branchiate chaetigers double. Upper tips of notopodial postchaetal lamellae rounded after chaetigers 4–6. Adults up to 0.8 mm wide... L. grimaldii n. sp.