taxonID	type	description	language	source
C268879DFF847232E0AAECBEFCADE639.taxon	materials_examined	Type species. Orbiniella minuta Day, 1954	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF847232E0AAECBEFCADE639.taxon	diagnosis	Diagnosis. Body not divided into thorax and abdomen, prostomium rounded. Eyes present or absent. Two peristomial annuli. Chaetigerous segments without branchiae or parapodial lobes; chaetae including crenulated capillaries and simple acicular spines. Noto- and neuropodial capillaries either smooth, with two rows of wide teeth along the margins, or with transverse rows of short spines. Teeth sometimes bearing long hairs at distal tips. Short and thick acicular spines (smooth or barbed) maybe present in both parapodial rami or only in neuropodia. Pygidium with two or four lobes, with or without cirri.	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF847232E0AAECBEFCADE639.taxon	discussion	Remarks. Originally, Day (1954) did not provide a diagnosis of the genus Orbiniella, which is later provided by Fauchald (1977) and more recently by Solís-Weiss & Fauchald (1989), Buzhinskaja (1993) and Gillet (1999). The diagnosis followed here is that proposed by Buzhinskaja (1993), which has been slightly modified to avoid ambiguous terms such as “ first two segments ”; those refer to the two achaetous anterior rings. Furthermore, we consider that the pygidium may be either bilobed (as referred for previously described species) or four-lobed (the new species described herein). There has also been confusion over the location of the peristomium and first segment in the Orbiniidae in general (Rouse 2002) and in Orbiniella in particular. Thus, genera of the Microrbiniinae Blake, 2000 have two annuli between the prostomium and the first chaetiger. Some authors consider that one of them is an “ achaetous segment ” (Day 1977; Fauchald 1977; Solís-Weiss & Fauchald 1989); alternatively, the peristomium would be constituted by two rings (Blake 1996). We consider that the latter would be more plausible; however, using the number of peristomial rings for separating genera or species may be not a reliable character (Blake 2000). Furthermore, the division of body into thorax and abdomen through transitional segments and presence of furcate chaetae does not seem appropriate to characterize the genus Orbiniella (Buzhinskaja 1993) and therefore O. drakei should not be included in this genus. Likewise, the presence of branchiae in O. branchiata suggests that this species should be referred to other genus (Blake 2000). Buzhinskaja (1993) also suggests that Falklandiella annulata should be transferred to Orbiniella, according to the original description and drawings by Hartman (1967). Blake (2000) considers it as valid although Fauchald (1977) places this genus as incertidae sedis but still recognising that resembles the orbiniids in chaetal features.	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF84723CE0AAE975FBB5E06B.taxon	materials_examined	Material examined. A total of 222 specimens of Orbiniella petersenae sp. nov. were collected. Holotype: IINH 35670 (BIOICE sample 3636; 1,844 − 1,849 m depth, incomplete specimen). Paratypes: IINH 29795 (BIOICE sample 2430; 1,007 − 1,016 m; 26 spec.); IINH 34892 (BIOICE sample 2444; 133 − 148 m; 2 spec.); IINH 34894 (BIOICE sample 3611; 188 − 197 m; 16 spec. EtOH fixed); IINH 35669 (BIOICE sample 3632; 6 specimens on SEM stub); IINH 35671 (BIOCE sample 3636; 1,844 − 1,849 m; 94 spec.); IINH 35672 (BIOCE sample 3636; 1 posterior end;); MNCN 16.01 / 16549 (BIOICE sample 3636; 19 paratypes); IINH 29822 (BIOICE sample 3640; 1,908 − 1,915 m; 46 spec.); IINH 34897 (BIOICE sample 3640; 1 posterior end on SEM stub); IINH 35673 (BIOICE sample 3640; 3 specimens imaged with µCT); IINH 34899 (BIOICE sample 3656; 1,490 − 1,492 m; 9 spec.; EtOH fixed).	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF84723CE0AAE975FBB5E06B.taxon	description	Description of holotype. Anterior fragment, body of uniform width, 6.0 mm long, 0.3 mm wide at level of first chaetiger, with 25 chaetigers; no body external regionalization (Fig. 3 A), lacking pigmentation. Prostomium rounded, wider than long (Fig. 3 B – C), provided with two dorsal brownish semi-lunar patches (diffuse photoreception area with ocelli?). No conspicuous nuchal organs observed. Two achaetous peristomial annuli, first narrower than second, distinctly separated from first chaetiger (Fig. 3 B – C). From CH 9 onwards segments becoming longer, more square-shaped (Fig. 3 A). Segment annulation not clear under light microscope (but see SEM observations of paratypes below). Notopodia with small, postchaetal papilla present from CH 1, sometimes located in between the two parapodial rami; papilla absent in neuropodia (Fig. 3 B and also see SEM micrographs of paratypes: Figs 4 A, 5 C, 6 C, E). Notopodia and neuropodia bearing each 7 – 10 long crenulated capillaries and 1 – 3 short, stout smooth aciculae (Fig. 3 C and also see SEM micrographs of paratypes: Figs 5 C – F, 6 C, E); capillary chaetae with crenulation occurring on one side along half length. Capillaries in first segments longer than body width (Fig. 3 B). Variation. The study of paratypes under stereomicroscope and SEM allowed elucidating the structure and range of variability of some body features. The species shows great body fragility; despite the high number of specimens obtained, none was complete. Longer anterior fragments are of about 23 chaetigers. SEM micrographs showed lateral ciliary spots at both sides of prostomium (Fig. 4 E – F), which might represent nuchal organs (see Discussion). Annulation of segments between parapodial rami follows this pattern: one ring between CH 1 and CH 2, two rings between CH 2 – CH 6 (5) and three rings from CH 6 (5) (Figs 4 A – D, 5 A – B); annulation is less defined in pre-pygidial region (Fig. 6 D). Annulation is lost when segments are conspicuously elongated (Fig. 6 A – B). Notopodial papilla is always present from CH 1 (Fig. 5 C). Neuropodial papilla was not observed. Capillary and acicular chaetae are present in both rami from CH 1 (Fig. 5 C – F). Capillaries are long and numerous (9 – 10 per bundle) in the first 5 – 6 chaetigers (Fig. 4 A, C); acicular chaetae numbering up to 3 per rami. Last 5 – 6 posterior segments suddenly become much shorter acquiring a crowded appearance (Fig. 6 A, D); these look achaetous but show small lateral projections (= small parapodia; Fig. 6 D, black arrowhead). In some cases, body shows an inflated region just before the pygidium (see Blake 1985) which is probably a fixation artefact (Fig. 2 F). The pygidium is provided with four lobes (Figs 3 D – E, 6 D, F). Gross internal anatomy. The study of three paratypes (IINH 35673) under the µCT allowed exploring for the first time the gross internal anatomy of any species of the genus Orbiniella (Figs. 7 – 9). The main findings were: (1) Body general cavity is well separated by septa (Figs 7 A, 8 A, 9 A, C), and is mostly filled by the digestive system (Figs 7 B, 8 A, 9 B) and maturing sexual cells (oocytes) (Figs 7 A – C, 8 A, C – D, 9 B, E – F). (2) Digestive system shows conspicuous regionalization (Figs 7 B, 9 B) and is suspended by developed dorsal and ventral mesenteries (Fig. 9 E): Species Eyes Nuchal Achaetous segments Segmental annulation Capillary chaetae Preanal Pygidium organs segments 2	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF84723CE0AAE975FBB5E06B.taxon	etymology	Etymology. The species is named after Danish polychaetologist Dr. Mary E. Petersen, who has recently passed away. Mary first suggested that these specimens might constitute a new species and her notes and drawings inspired this paper.	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
C268879DFF84723CE0AAE975FBB5E06B.taxon	distribution	Distribution. Specimens were collected in two areas characterized by different predominant water masses (Fig. 1). Some of them were found on the shelf and slope (133 to 1,007 m depth) of SW Iceland, off Faxafloi Bay to South of Vestmannaeyjar Island, in warmer waters (4.8 to 7.4 ºC). Most specimens were collected on the slope off NE Iceland, in Arctic colder, deeper waters (- 0.7 to - 0.8 ºC; 1,490 to 1,915 m).	en	Parapar, Julio, Moreira, Juan, Helgason, Gudmundur Vidir (2015): First record of genus Orbiniella Day, 1954 (Polychaeta: Orbiniidae) in North Atlantic Ocean with the description of a new species. Zootaxa 4006 (2): 330-346, DOI: 10.11646/zootaxa.4006.2.5
