Laonice Malmgren 1867

Laonice Malmgren, 1867 (emended)

Type species: Nerine cirrata M. Sars, 1851. By monotypy.

Diagnosis. Prostomium anteriorly rounded or slightly concave, either T- or skittle-shaped, clearly fused with peristomium at anterior angles (subgenus Laonice), fused only by a thin membrane normally sunken in a groove between prostomium and peristomium (part of subgenus Sarsiana), or not fused at all (part of subgenus Sarsiana and subgenus Appelloefia). Occipital antenna present (most usual), absent or with variable presence (e.g., in Laonice bahusiensis Söderström, 1920). Caruncle well developed, long (except in the deep-sea species Laonice (Sarsiana) magnacristata Maciolek, 2000 and Laonice (Laonice) plumisetosa Bogantes, Halanych & Meissner, 2018), extending posteriorly over several chaetigers following a pair of nuchal organ loops starting from palp attachments. Nuchal organs long and widely variable in length (subgenus Laonice) or short (usually around 10 chaetigers, always less than 20) and less variable in length (subgenera Sarsiana and Appelloefia). Palps often long, without sheath at base. Peristomium not fused with chaetiger 1. Parapodia biramous; each ramus of anterior chaetigers with three tufts of long, thin capillary chaetae, including anterior and posterior parallel vertical rows of chaetae arranged in single lines (except in subgenus Appelloefia, with more than two rows of capillaries in several anteriormost chaetigers), with a third tuft inserted above (notopodia) and below (neuropodia) these rows. Inferior neurochaetae or sabre chaetae [“Haarborsten” in Söderström (1920)] appearing in anterior region, being longer and stouter than ordinary capillaries. Neuropodial hooks with primary hood only, with chaetiger of first appearance varying; notopodial hooks generally absent (may be present in posteriormost chaetigers in some species of subgenus Sarsiana). Dorsal branchiae from chaetiger 2, separated from notopodial postchaetal lamellae and on a variable number of anterior chaetigers, rarely up to body end (e.g., in subgenus Appelloefia). Lateral inter-neuropodial pouches on a variable number of anterior chaetigers, often up to body end, rarely absent; first chaetiger with pouches varying. Anus terminal, surrounded by two ventral lobes or small papilliform cirri (usually placed close together) and several pairs of comparatively long, thinner dorsal anal cirri. Pigmentation absent.