Orbiniella parapari Meca & Kongsrud & Kongshavn & Alvestad & Meißner & Budaeva 2024, sp. nov.
Creators: name: Meca, Miguel A.
name: Kongsrud, Jon Anders
name: Kongshavn, Katrine
name: Alvestad, Tom
name: Meißner, Karin
name: Budaeva, Nataliya
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Orbiniida
Orbiniidae
Orbiniella
Orbiniella parapari

description: Orbiniella parapari Meca & Budaeva, sp. nov.
Figs 8, 9, 10
Orbiniella petersenae: Parapar et al. (2015): 333–343, figs 3–9 (in part).
Clade.
Deep 2.
Type material examined.
Holotype ZMBN 157405 (DNA voucher Orbi 40). Paratypes ZMBN 157406 (8 paratypes); ZMBN 157407 (1 paratype on SEM stub); ZMBN 157408 (9 paratypes); ZMBN 157409 (2 paratypes on SEM stub); ZMBN 157410 (1 paratype on SEM stub); ZMBN 157411 (1 paratype, DNA voucher Orbi 37); ZMBN 157412 (1 paratype on SEM stub, DNA voucher Orbi 38); ZMBN 157413 (1 paratype on SEM stub, DNA voucher Orbi 38); ZMBN 157414 (3 paratypes); ZMBN 157415 (4 paratypes); ZMBN 157416 (1 paratype); ZMBN 157417 (1 paratype); ZMBN 157418 (2 paratypes); ZMBN 157424 (3 paratypes); ZMBN 157425 (8 paratypes); ZMBN 157426 (2 paratypes); ZMBN 157429 (2 paratypes on SEM stub); SMF 32659 (3 paratypes); SMF 32662 (5 paratypes); SMF 32644 (1 paratype); SMF 32653 (4 paratypes); SMF 32655 (5 paratypes); SMF 32664 (1 paratype, DNA voucher Orbi 26); SMF 32666 (4 paratypes); SMF 32667 (1 paratype, DNA voucher Orbi 10); SMF 32668 (1 paratype on SEM stub, DNA voucher Orbi 11); SMF 32669 (1 paratype on SEM stub, DNA voucher Orbi 12); SMF 32680 (1 paratype).
Other material examined.
ZMBN 157427 (4 spms); ZMBN 157428 (45 spms); ZMBN 157430 (30 spms); ZMBN 157431 (4 spms); ZMBN 157675 (E-voucher NBAAV 687-23); ZMBN 157676 (E-voucher NBAAV 689-23); ZMBN 157677 (E-voucher NBAAV 691-23); ZMBN 157678 (E-voucher NBAAV 690-23); ZMBN 157679 (E-voucher NBAAV 694-23); ZMBN 157680 (E-voucher NBAAV 688-23); SMF 32652 (8 spms); SMF 32654 (2 spms); SMF 32657 (39 spms); IceAGE sample DZMB - HH 33669 (E-voucher NBAAV 668-23); IceAGE sample DZMB - HH 49578 (E-voucher NBAAV 671-23); IceAGE sample DZMB - HH 49614 (E-voucher NBAAV 669-23); IceAGE sample DZMB - HH 49614 (E-voucher NBAAV 670-23); 56 specimens from the O. petersenae sensu lato type series: IINH 43199 (40 spms), IINH 43197 (16 spms).
Diagnosis.
An Orbiniella with segmental annulation pattern as follows: one narrow annulus between parapodia from parapodium 1 until 5 or 6, two narrow annuli between parapodia from parapodium 5 or 6 until 10–14, and three narrow annuli between parapodia from parapodium 10–14 until pygidium. Acicular spines long and thin, up to six in both noto- and neuropodia. Pygidium with four short and thick anal lobes.
Type locality.
Loki’s Castle, Arctic Mid-Ocean Ridge, 73.5663, 8.1610, 2450 m (Fig. 8).
Description
(based on type specimens). Holotype complete with 29 chaetigers, 4.3 mm long and 0.5 mm wide at level of chaetiger 6. Body short and thick, uniformly wide, narrowing in preanal area. Pigmentation lacking. Prostomium broad with rounded anterior margin, without eyespots (Fig. 9 A). Peristomium with two prominent achaetous segments, first peristomial segment shorter than second, distinctly separated from each other and first chaetiger by narrow annulus (Fig. 9 A). No conspicuous nuchal organs observed. Anterior segments short, becoming longer, more square-shaped from chaetiger 8 onwards. Segmental annulation of following pattern: one narrow annulus between parapodia from parapodium 1 until 5 or 6, two narrow annuli between parapodia from parapodium 5 or 6 until 10–14, and three narrow annuli between parapodia from parapodium 10–14 until pygidium (Fig. 10 A, B). Segmental annulation less defined in pre-pygidial region.
Parapodia biramous, wider than long (Fig. 9 C), with postchaetal notopodial lobe digitate, short, and thick from chaetiger 1. Postchaetal neuropodial lobe absent. Crenulated capillary chaetae and acicular spines present in both rami from chaetiger 1. Capillaries in anterior segments longer than body width and numerous (7–10 per bundle), in posterior segments shorter and reduced in number. Acicular spines long, thin, and smooth, up to six per ramus (Fig. 9 E).
Last five or six posterior segments slightly shorter and last two achaetous (Fig. 10 C). Pygidium with four short and thick anal lobes (Fig. 10 D).
Variation.
The holotype and all paratypes collected from the Loki’s Castle vent field shared the same morphology. Other paratypes collected from the Iceland Sea and the Norwegian Sea showed variation in the shape of prostomium, peristomium and notopodia.
Some of the specimens collected in the IceAGE project displayed three different patterns of dorsal segmental pigmentation: lateral patches from chaetiger 3 to the rest of the body; transversal bands through all the segment in chaetigers 3, 4, and 5 and in patches in the remaining chaetigers; bands in chaetiger 3, 4, and 5 without pigmentation in the rest of the body. The remaining pigmentation might be due to more recent collection date of the IceAGE specimens comparable to the type material.
The shape of prostomium varied between being broad (Figs 9 A, 10 A) or elongate, with a rounded anterior margin. Poorly defined brownish eyespots were observed in some of the specimens from the O. petersenae sensu lato type series material. Most of the paratypes had the first segment of the peristomium shorter than the second, as in the holotype, but a few paratypes were with both segments equal in length. Notopodia varied between being digitate, long, and thin or digitate, short, and thick (Fig. 9 D, F; Table 1).
SEM micrographs of several paratypes showed one single prominent lateral ciliary congregation at each side of the prostomium, which we interpreted as nuchal organs (Fig. 9 B). Capillary chaetae with crenulation occurring on one side along the whole chaeta (Fig. 9 D) or along half of its length (Fig. 9 F). Crenulation can be clear along the whole chaeta or become more obvious distally. The specimens from the O. petersenae sensu lato type series and the holotype showed capillaries longer than body width in anterior segments as Parapar et al. (2015) stated. However, other specimens from the material collected in this study presented shorter capillaries equal to body width.
Remarks.
Among the Nordic Orbiniella species described here, O. parapari sp. nov. closely resembles O. petersenae sensu stricto, with which it has overlapping geographical ranges (i. e., Iceland Sea and Norwegian Sea). Both species are similar in bearing high number of acicular spines (i. e., 1–5 per ramus in the former and 1–6 in the latter), which, however, appear longer and thinner in O. parapari sp. nov. Also, both species share a pygidium with four short, thick anal lobes, although the lobes are slightly shorter and thicker in O. parapari sp. nov. Both species also have one, two, and three narrow annuli between parapodia; however, their pattern of progression along the body differs: 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, and continuing with three narrow annuli between parapodia in O. parapari sp. nov.; and an anterior-most region bearing one and two narrow annuli between parapodia followed by an extensive region with three narrow annuli between parapodia in O. petersenae sensu stricto. Orbiniella griegi sp. nov. also shows one to three narrow annuli between parapodia (with a different pattern, see the description of O. griegi), but has fewer (1 or 2) acicular spines and a pygidium with four long anal lobes assembled together.
As in the case of the other Nordic Orbiniella species described here, O. parapari sp. nov. shares a number of morphological characters with the seven deep-sea congeners: O. andeepia, O. longilobata, O. rugosa, O. tumida, O. abyssalis, O. armata, and O. mimica (see details on similarities and dissimilarities of these species with respect to O. mayhemi sp. nov.). However, O. parapari sp. nov. differs from these seven species in having three intersegmental rings, and with the exception of O. mimica, a pygidium bearing four short anal lobes. Orbiniella mimica also bears four lobes in the pygidium, but they are much shorter than in O. parapari sp. nov. and each of them is accompanied by a long, thin anal cirrus. Moreover, O. mimica presents a unique papillated dorsal surface and a smaller number (up to 3) of acicular spines than in O. parapari sp. nov. (up to 6 spines).
Distribution.
Iceland Sea and Norwegian Sea, 1811–2832 m (Fig. 8).
Etymology.
This species is dedicated to the Spanish polychaetologist Dr. Julio Parapar, who described the first Orbiniella species in the North Atlantic waters, Orbiniella petersenae Parapar, Moreira & Helgason, 2015.
description: Published as part of Meca, Miguel A., Kongsrud, Jon Anders, Kongshavn, Katrine, Alvestad, Tom, Meißner, Karin & Budaeva, Nataliya, 2024, Diversity of Orbiniella (Orbiniidae, Annelida) in the North Atlantic and the Arctic, pp. 51-88 in ZooKeys 1205 on pages 51-88, DOI: 10.3897/zookeys.1205.120300