Diversity of Orbiniella (Orbiniidae, Annelida) in the North Atlantic and the Arctic Author Meca, Miguel A. 0000-0002-3798-6809 Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway Author Kongsrud, Jon Anders Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway Author Kongshavn, Katrine 0000-0002-4265-0912 Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway Author Alvestad, Tom Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway Author Meißner, Karin Senckenberg Forschungsinstitute und Naturmuseun, German Centre for Marine Biodiversity Research, Hamburg, Germany Author Budaeva, Nataliya 0000-0001-9748-2285 Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway text ZooKeys 2024 2024-06-20 1205 51 88 journal article 298694 10.3897/zookeys.1205.120300 47fc80ed-d24b-46c5-b58a-8b480d808001 A94034D3-8B98-461D-A58B-23654551B5D5 Orbiniella griegi Meca & Budaeva , sp. nov. Figs 3 , 4 , 5 Orbiniella petersenae : Parapar et al. 2015: 333–343 , figs 3–9 (in part). Clade. Shallow. Type material examined. Holotype ZMBN 157444 (DNA voucher Orbi 43) . Paratypes ZMBN 157397 ( 1 paratype , DNA voucher Orbi 32) ; ZMBN 157398 ( 1 paratype , DNA voucher Orbi 33) ; ZMBN 157399 ( 1 paratype , DNA voucher Orbi 30) ; ZMBN 157400 ( 1 paratype , DNA voucher Orbi 31) ; ZMBN 157401 ( 3 paratypes ) ; ZMBN 157402 ( 22 paratypes ) ; ZMBN 157403 ( 1 paratype , DNA voucher Orbi 28) ; ZMBN 157404 ( 1 paratype , DNA voucher Orbi 27) ; ZMBN 157434 ( 1 paratype ) ; ZMBN 157435 ( 1 paratype ) ; ZMBN 157436 ( 1 paratype on SEM stub) ; ZMBN 157437 ( 1 paratype ) ; ZMBN 157438 ( 1 paratype ) ; ZMBN 157439 ( 1 paratype ) ; ZMBN 157440 ( 1 paratype on SEM stub) ; ZMBN 157441 ( 1 paratype ) ; ZMBN 157442 ( 5 paratypes ) ; ZMBN 157443 ( 1 paratype ) ; ZMBN 157445 ( 1 paratype , DNA voucher LC- 57) ; ZMBN 157446 ( 1 paratype ) ; ZMBN 157646 ( 1 paratype ) ; SMF 32601 ( 1 paratype , DNA voucher Orbi 4) ; SMF 32637 ( 1 paratype ) ; SMF 32639 ( 1 paratype , DNA voucher Orbi 17) ; SMF 32665 ( 1 paratype , DNA voucher Orbi 5) . Other material examined. ZMBN 95697 (1 spm); ZMBN 95728 (E-voucher POLNB 1250 -14); ZMBN 95735 (E-voucher POLNB 1257 -14); ZMBN 157668 (E-voucher ICBA 263-16); ZMBN 157669 (E-voucher ICBA 264-16); ZMBN 157670 (E-voucher NBAAV 696-23); ZMBN 157671 (E-voucher NBAAV 686-23); ZMBN 157672 (E-voucher NBAAV 697-23); ZMBN 157673 (E-voucher NBAAV 692-23); ZMBN 157674 (E-voucher NBAAV 693-23); 18 specimens from the O. petersenae sensu lato type series: IINH 34892 (2 spms); IINH 34894 (16 spms). Diagnosis. An Orbiniella with segmental annulation pattern as follows: one narrow annulus between parapodium 1 and 6, two narrow annuli between parapodia from parapodium 6 until 8, and three narrow annuli between parapodia from parapodium 8 until pygidium. Acicular spines short and stout, up to two in both noto- and neuropodia. Pygidium with four long anal lobes assembled together. Type locality. Basvika, Bergen area, Norwegian West coast , 60.3959 , 5.1492 , 172 m (Fig. 3 ). Figure 3. Distribution of Orbiniella griegi Meca & Budaeva , sp. nov. Black lines – Greenland-Scotland Ridge (GSR), star – type locality, coloured triangles – stations with examined morphology and molecular data, white triangles – stations with examined morphology. Description (based on type specimens). Holotype complete with 32 chaetigers, 4.9 mm long and 0.4 mm wide at level of chaetiger 7. Body elongated and narrow, uniformly wide, slightly narrowing in pre-pygidial area. Pigmentation lacking in all analysed specimens. Prostomium broad with rounded anterior margin, without eyespots (Fig. 4 A ). SEM micrographs showed two lateral, inconspicuous ciliary spots on both sides of prostomium, presumably nuchal organs (Fig. 4 B ). Peristomium with two prominent achaetous segments, second shorter than first, distinctly separated from each other and from first chaetiger by narrow annulus (Fig. 4 A ). From chaetiger 7–10 onwards segments becoming longer, more square-shaped. Segmental annulation in following pattern: one narrow annulus between parapodium 1 and 6, two narrow annuli between parapodia from parapodium 6 until 8, and three narrow annuli between parapodia from parapodium 8 until pygidium (Fig. 5 A – C ). Segmental annulation less defined in pre-pygidial region. Figure 4. Orbiniella griegi Meca & Budaeva , sp. nov. , SEM A paratype ZMBN 157440 , anterior end, dorsal view B paratype ZMBN 157440 , detail of right lateral side of prostomium showing presumable nuchal organ (insert of A ) C paratype ZMBN 157440 , notopodium of chaetiger 20 showing notopodial lobe and acicular spine D paratype ZMBN 157436 , parapodium of chaetiger 7 showing acicular spines disposed in vis-à-vis position and capillaries E paratype ZMBN 157436 , neuropodium of chaetiger 9 showing acicular spines and capillaries F paratype ZMBN 157440 , capillary chaetae. Black arrows in B : Lateral ciliary spots; White arrow in E : Start of crenulation in capillary chaeta. Abbreviations: Ac: acicular spines; Np: notopodial lobe. Scale bars: 100 μm ( A ); 20 μm ( B, D, E ); 10 μm ( C, F ). Figure 5. Orbiniella griegi Meca & Budaeva , sp. nov. , SEM A paratype ZMBN 157436 , anterior end, dorsal view showing narrow annuli between parapodia 1 and 8 B paratype ZMBN 157436 , mid body, dorsal view showing narrow annuli between parapodia 9 and 16 C paratype ZMBN 157440 , posterior end, dorsal view D paratype ZMBN 157440 , detail of pygidium (insert of C ). Numbers show the segmental annulation pattern. Abbreviations: Par 1: first parapodium; Par 6: sixth parapodium. Scale bars: 200 μm ( A ); 100 μm ( B – D ). Parapodia biramous, triangular-like, of similar size throughout body. Postchaetal neuropodial lobe absent. Digitate postchaetal notopodial lobes short and thick, from chaetiger 1 (Fig. 4 C ). Crenulated capillary chaetae and spines present in both rami from CH 1. Capillaries equal in length to body width and numerous (6–8 per bundle) in anterior segments; shorter and reduced in number in posterior segments. Capillary chaetae with crenulation occurring on one side along whole chaeta or along half of its length (Fig. 4 E ). Spines short, stout, smooth, one or two per ramus (Fig. 4 D ). Last eight or nine chaetigers short and few achaetous (Fig. 5 C ). Pygidium with four long anal lobes assembled together (Fig. 5 D ). Variation. The holotype and most of the paratypes shared the same morphology. However, some paratypes collected from the Norwegian shelf presented more numerous (7–10 per bundle) and longer (longer than body width) capillaries in anterior segments compared to specimens from the type locality Remarks. Orbiniella griegi sp. nov. is morphologically nearly identical to the other three species described in this work: O. mayhemi sp. nov. , O. parapari sp. nov. and O. petersenae sensu stricto , which led to combining them into a single species by Parapar et al. (2015) . However, the four species display differences in the segmental annulation pattern in the anterior body (i. e., an anterior-most region with one narrow annulus between parapodia followed by a short region with two narrow annuli between parapodia in O. griegi sp. nov. , an anterior-most region with one narrow annulus between parapodia followed by a region bearing two narrow annuli between parapodia that extends to mid-posterior body in O. mayhemi sp. nov. , an anterior-most region with one narrow annulus between parapodia followed by a region bearing two narrow annuli between parapodia that extends to mid-anterior body in O. parapari sp. nov. , and an anterior-most region bearing one and two narrow annuli between parapodia followed by a region with three narrow annuli between parapodia in O. petersenae sensu stricto ) (Fig. 2 ). Orbiniella griegi sp. nov. also differs from the other species by having one or two short and stout acicular spines while O. mayhemi sp. nov. has 1–3 short spines, O. parapari sp. nov. has 1–6 long and thin spines, and O. petersenae sensu stricto bears 1–5 short spines. It can further be distinguished by having long anal lobes assembled together while O. parapari sp. nov. and O. petersenae sensu stricto bear short lobes on their pygidia (Fig. 2 ). The shape of the lobes is unknown in O. mayhemi sp. nov. (see also Table 1 with comparison of the Nordic Orbiniella species ). Orbiniella griegi sp. nov. also showed no intraspecific variation in the shape of prostomium, peristomium and notopodia. Orbiniella griegi sp. nov. resembles O. mayhemi sp. nov. in having a broad prostomium, but differs in the second peristomial segment being shorter than the first instead of the first segment being shorter than the second. Furthermore, both O. griegi sp. nov. and O. mayhemi sp. nov. bear digitate notopodial lobes, but showing slightly narrowing basal part in the latter. Table 1. Discriminatory characters of the NE Atlantic Orbiniella . Abbreviations: Af , Available fragment; CH , Chaetiger; NA , Narrow annuli between parapodia; Par , Parapodium; Pg , Pygidium.

Character	Orbiniella griegi sp. nov.	Orbiniella mayhemi sp. nov.	Orbiniella parapari sp. nov.	Orbiniella petersenae sensu stricto Parapar, Moreira & Helgason, 2015
Prostomium	Broad	Broad	Broad or elongate	Broad or elongate
Nuchal organs	In patches	Not observed	One single congregation	One single congregation
Peristomial rings	First wider than second	first narrower than second	Both with same length or first narrower than second	Both with same length or first narrower than second
Segmental annulation pattern	One NA from Par 1 until 6, two NA from Par 6 until 8, and three NA from Par 8 until Pg	One NA from Par 1 until 5-6 and two NA from Par 5-6 until end of Af of the most complete specimen	One NA from Par 1 until 5-6, two NA from Par 5-6 until 10-14, and three NA from Par 10-14 until Pg	One NA between Par 1 and 2, two NA from Par 2 until 5-6, and three NA from Par 5-6 until Pg
Shape parapodia	Triangular	Rounded in the first chaetigers and triangular from CH 7 – CH 10	Triangular or rounded in the first chaetigers and triangular from CH 7 – CH 10	Triangular or rounded in the first chaetigers and triangular from CH 7 – CH 10
Shape notopodia	Digitate (short)	Digitate (short) with slightly narrowing basal part	Digitate (short or long)	Digitate (short or long)
Capillaries	6-10 per bundle	6-10 per bundle	7-10 per bundle	7-10 per bundle
Spines	1-2 per ramus (short)	1-3 per ramus (short)	1-6 per ramus (long)	1-5 per ramus (short)
Pygidium	Four long lobes assembled together	Not observed	Four short and thick lobes	Four short lobes
Distribution	Norwegian shelf, Faroe-Iceland Ridge and SW Iceland	SW and SE Iceland	Iceland Sea and Norwegian Sea	Iceland Sea, Norwegian Sea and southern Greenland Sea
Depth	171-781 m	913-2505 m	1811-2832 m	1053-2407 m

Orbiniella griegi sp. nov. , together with O. marionensis Gillet, 1999 , are unique among the known shallow water Orbiniella species in having notopodial postchaetal lobes and in having acicular spines in both noto- and neuropodia, as in the seven deep-sea species: O. andeepia Narayanaswamy & Blake, 2005 , from Antarctica , O. longilobata Blake, 2020 , from South China Sea, O. rugosa Blake, 2020 , from South China Sea, O. tumida Blake, 2020 , from the California continental slope, O. abyssalis Blake, 2020 , from the abyssal Pacific Ocean, O. armata Blake, 2021 , from off South Carolina, and O. mimica Blake, 2021 , from NW Atlantic. Orbiniella griegi sp. nov. differs from these species in having three narrow annuli between parapodia and a pygidium with four anal lobes assembled together and from O. abyssalis , additionally, in having two peristomial segments instead of a single peristomial segment. Distribution. Norwegian coastal areas and shelf, Faroe-Island Ridge, and SW Iceland , 171–781 m (Fig. 3 ). Etymology. This species is named in honour of Edvard Grieg, the Norwegian musician born and raised in Bergen, the city where the present study was conducted.