The number of described species of the genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) has greatly increased in the last years, particularly in the North East Atlantic. In this context, this paper deals with several putative species recently delineated by molecular means within a well delimited clade of Terebellides. Species are characterised here by a combination of morphological characters, and a complementary nucleotide diagnostic approach. Three species were identified as the nominal species T. stroemii Sars, 1835, T. bigeniculatus Parapar, Moreira & Helgason, 2011 and T. europaeaLavesque et al., 2019. Five species are described as new: T. bakkenisp. nov., T. kongsrudisp. nov., T. norvegicasp. nov., T. ronningaesp. nov. and T. scoticasp. nov. The distinctive morphological characters refer to the branchial shape, absence or presence of papillae on lamellae of anterior margin of branchial dorsal lobes, absence or presence of ciliated papillae dorsal to thoracic notopodia, geniculate chaetae in one or two chaetigers, and the morphology of thoracic and abdominal uncini teeth. Furthermore, the description of T. bigeniculatus is revised and complemented after examination of type specimens. An updated identification key to all species of the genus in NE Atlantic and a proposal of a classification of different types of abdominal uncini to be used in taxonomy are also included.

The study of material collected during routine monitoring surveys dealing with oil extraction and aquaculture in waters off Myanmar (North Andaman Sea) and in the Gulf of Thailand, respectively, allowed us to analyse the taxonomy and diversity of the polychaete genusTerebellides(Annelida). Three species were found, namelyTerebellidescf.woolawa,Terebellides hutchingsaespec. nov.(a new species fully described and illustrated), andTerebellidessp. (likely a new species, but with only one available specimen). The new species is characterised by the combination of some branchial (number, fusion and relative length of lobes and papillation of lamellae), and thoracic (lateral lobes and relative length of notopodia) characters and is compared with all species described or reported in the SW Indo-Pacific area, as well as with those sharing similar morphological characteristics all around the world. The taxonomic relevance of the relative length of branchial lobes and different types of ciliature in branchial lamellae for species discrimination in the genus is discussed. A key to allTerebellidesspecies described in SE Indo-Pacific waters is presented.

Diversity of the genus Terebellides (Polychaeta: Trichobranchidae) in the Adriatic Sea with the description of a new species

The family Oweniidae Rioja, 1917 is a small group of broadly distributed polychaetes whose relationships and position in the annelid tree are still po

Based on the study of specimens previously identified as Myriochele heeri Malmgren, 1867 Malmgren, A. J. 1867. Spetsbergens, Grönlands, Islands och den Skaninaviska halföns hittills kända Annulata Polychaeta, 127 Helsingfors: Frenkell and Son. [Google Scholar] (Polychaeta, Oweniidae) in Icelandic waters collected during the BIOICE project, a redescription of this taxon is presented, a Pacific species—Myriochele olgae Blake, 2000 Blake, J. A. 2000. “Family Oweniidae Rioja, 1917.”. In Taxonomic atlas of the benthic fauna of the Santa Maria Basin and the Western Santa Barbara Channel. Volume 7, The Annelida part 4: Polychaeta: Flabelligeridae to Sternaspidae, Edited by: Blake, J. A , Hilbig, B and Scott, P. V . 97–127. Santa Barbara (CA): Santa Barbara Museum of Natural History. [Google Scholar] —is reported, and one new species is described: Myrioglobula malmgreni sp. nov. Myriochele heeri is characterized by three short anterior uniramous chaetigers of similar length. The revision of the type series of M. heeri showed that the length of the anterior chaetigers and the chaetal composition is variable in the different specimens, thus demonstrating that more than one species is involved. Complementary anatomical (prostomial, foregut, and peristomial ciliary fields, ventral pharyngeal organ) and biological (food composition, tube ornamentation, body regeneration) observations from selected specimens are provided. Additions to the original description of Myrioglobula islandica Parapar, 2003a and an updated key to the species of Oweniidae recorded in Arctic and East Atlantic Boreal waters are also presented. Aspects on geographical distribution and phylogeny of the family are also discussed.