Corresponding author: Sergio I. Salazar-Vallejo (
Academic editor: Chris Glasby
Most sternaspid species have been described from shallow water, and
In the polychaete family
The study of the Pacific Ocean sternaspid material lodged in six major research institutions resulted in the recognition of six species which are newly described:
Specimens were cleaned with a small brush; measurements were made with a millimeter ruler and the ventro-caudal shield was measured with a micro ruler with 0.1 mm marks. Ventro-caudal shield fascicles were counted by viewing the chaetal bases end on because most were broken. Collapsed specimens were re-swollen by injecting the same preserving fluid with a syringe. Illustrations were prepared by assembling series of photographs by using HeliconFocus. Character choice and terminology follows a recent revision (
California Academy of Sciences, San Francisco
Natural History Museum of Los Angeles County, Allan Hancock Polychaete Collection, Los Angeles
Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow
Colección de Referencia de Invertebrados Bentónicos, Unidad Académica Mazatlán, UNAM, Mazatlán
Zoological Institute, Russian Academy of Sciences, Saint-Petersburg
Zoological Museum, University of Copenhagen
Sternaspids with introvert hooks falcate, tapered. Pre-shield region with 7 segments. Ventro-caudal shield flexible, usually with abundant sediment particles firmly adhered, rarely sediment particles loosely adhered; without well-defined radial ribs and concentric lines. Branchial filaments arranged in discrete branchial plates.
Holotype (LACM 5360) and paratype breaking into two pieces (
Prostomium minute globose, ovoid, brownish (
First three chaetigers with about 16 falcate, tapered introvert hooks per bundle, each with subdistal dark areas (tips broken, darker areas look distal; subdistal in complete hooks). Genital papillae not seen (paratype with ventrolateral pores between segments 7 and 8). Pre-shield region with 7 segments (difficult to count because of specimens fragility); capillary chaetae along first pre-shield segment (paratype with capillaries in two segments).
Ventro-caudal shield completely covered by a thick coating of adhered particles (
Marginal chaetal fascicles include 9 lateral and only 4–5 short, small posterior ones (others probably broken), each with 3–4 chaetae per bundle. Peg chaetae robust, forming thin, short spines, close to posterior margins. Additional chaetal fascicles not visible.
Branchiae lost. Interbranchial filaments lost. Branchial plates slightly divergent, anteriorly expanded, rounded (
This species is named after Dr. Kristian Fauchald, long-time teacher and friend, in recognition of his many contributions to polychaete systematics and especially because of his contribution to the study of deep-sea fauna including the off Oregon species. The epithet is a noun in the genitive case.
W off Yaquina Bay, 2800 m depth.
From Oregon to Southern California, in 1387–2800 m depth.
Holotype (CAS 129027h) with integument almost completely removed, some fragments remain in mid-body; body wall broken midventrally and dorsally (
Prostomium minute globose, ovoid, paler than peristomium. Peristomium small, oval, papillae lost. Mouth oval, small slightly wider than prostomium, barely projected, covered by papillae (
First three chaetigers with about 16 falcate, tapered introvert hooks per bundle, each with subdistal dark areas, slightly paler distally. Genital papillae not seen. Pre-shield region with 7 segments; capillary chaetae not seen (some paratypes with capillaries in 2–4 segments).
Ventro-caudal shield completely covered by a thin, delicate coating of adhered fine sediment particles, mostly removed from shield; suture not visible (
Marginal chaetal fascicles include 10 lateral and only 4 short, small posterior ones (others probably broken; some paratypes with up to six posterior bundles); lateral bundles with 7–8 chaetae each, posterior bundles with 5–6. Peg chaetae not visible (one paratype with minute, barely visible peg chaetae). Additional chaetal fascicles not visible.
Branchiae lost. Interbranchial filaments lost. Branchial plates convergent, anteriorly expanded, rounded. Some paratypes with broken body wall include oocytes, each about 200 µm.
All paratypes have shields without sediment particles firmly adhered or concentric lines (
The specific name is derived from the Latin adjective
Only known from off Oregon, U.S.A., in 2519 m depth.
1 | Shield with sediment particles firmly adhered; shield surface not visible | 2 |
– | Shield without firmly adhered sediment particles; shield surface visible | |
2(1) | Shield with anterior depression deep; peg chaetae robust | 3 |
– | Shield with anterior depression shallow; peg chaetae indistinct | |
3(2) | Shield with anterior margins angular; peg chaetae forming thick, large spines | |
– | Shield with anterior margins rounded; peg chaetae forming thin, small spines |
Sternaspids with introvert hooks falcate, tapered. Pre-shield region with 7 segments. Ventro-caudal shield stiff, usually with abundant sediment particles loosely adhered; with well-developed radial ribs and concentric lines. Branchial filaments arranged in discrete branchial plates.
Holotype (ZIRAS 50602) with body bi-colored; introvert not fully exposed, pale brown, abdomen whitish (
Prostomium hemispherical (
Introvert chaetigers with 10–11 golden barely falcate hooks, each with subdistal dark areas but tips mostly eroded (
Anterior abdomen with 7 segments, papillae mostly eroded, some remaining in body depressions or around branchial region, but not arranged in series or groups. Capillaries not seen (two paratypes with capillaries in first two segments, two per bundle).
Ventro-caudal shield with lateral plates divergent, surface with ribs and concentric lines, the latter less pronounced, barely banded; suture visible throughout shield. Anterior margins rounded, midventral depression shallow (
Marginal chaetal fascicles mostly broken off (
Branchiae mostly lost (few remaining in paratypes, spirally bent); interbranchial papillae long, straight, often with fine sediment particles. Branchial plates observed in some paratypes, narrow, anteriorly rounded, wider than rest of branchial plate, with 8–9 filaments per series.
This species name is after the late Dr. Nadezhda P. Annenkova, in recognition of her many publications on polychaetes, and for her efforts to build a strong taxonomic tradition in the early to mid XX century in Russia. The epithet is a noun in the genitive case.
The introvert is always pale brown, darker than the abdomen. Introvert chaetigers have 11–13 hooks per bundle. The ventro-caudal shield is pale brick red or dirty orange, ribs and concentric lines are always visible but variably developed; anterior margins are rounded to barely acute (
On the other hand,
Only known from the type locality in the Northwestern Pacific Ocean, east off northern Kurile Islands, in 3980–4070 m depth.
Holotype (LACM 0000) complete. Body wall broken and inner organs lost (
Prostomium eroded, small, ovoid, paler than surrounding areas, smaller than mouth (
First three chaetigers with 12–14 bronze, slightly falcate hooks per bundle, each with subdistal dark areas (up to 16–18 in some paratypes). Genital papillae lost (pale, blunt, short lobes in some paratypes, from the intersegmental groove between segments 7 and 8).
Pre-shield region with 7 segments, with papillae mostly eroded from segmental ridges, but present in intersegmental furrows or along some areas, homogeneously distributed. Short, about 4–5 capillary chaetae in some segments.
Ventro-caudal shield dark orange, with ribs partly eroded, concentric lines poorly developed; suture distinct throughout shield (
Marginal chaetae fascicles damaged; eight or nine lateral ones (10 in one paratype Sta. 72), chaetae ovally arranged, and six posterior ones (paratypes more damaged). Peg chaetae visible, not broken, but detached, and a single long, delicate chaetae.
Branchial plate missing (one paratype (Sta. 72) with one plate left but no branchial or interbranchial filaments left; branchial plate ovoid, tapering anteriorly; another paratype from the same station with branchial plates anteriorly converging).
There are several ontogenetic changes in the ventro-caudal shield, although the anterior depression remains shallow throughout their development (
The species name is after Dr Don Maurer in recognition of his many publications, mostly on benthic ecological studies and especially dealing with polychaetes. He also studied the material employed for this description. The epithet is a noun in the genitive case.
W off Trujillo, Perú, 6156–6489 m depth.
Abyssal sediments off Peru, Eastern Pacific, in 1296–6489 m water depths, and in the Southwestern Pacific in 795–3830 m.
Holotype (ZIRAS 50604) with body anteriorly swollen, slightly darker than posterior region; introvert fully exposed, pale, abdomen creamy (
Prostomium hemispherical (
Introvert chaetigers with 9–11 golden, barely falcate hooks, each with subdistal dark areas but tips mostly eroded (
Anterior abdomen with 7 segments, lateral lobes well-defined by contraction, dorsal area bare, converging posteriorly, ventral area bare, more or less parallel; papillae mostly eroded, some remaining in branchial region, but not arranged in series or groups. Capillaries not seen.
Ventro-caudal shield with lateral plates slightly bent dorsally, making them look quadrate in frontal view (
Marginal chaetal fascicles mostly broken off (
Branchiae still attached, abundant, spirally bent filaments; interbranchial papillae long, spirally bent, with fine sediment particles. Branchial plates observed in some paratypes, wide, progressively wider towards anterior margin, with 7–8 filaments per series.
This species is being named after the late Dr. Pavel V. Uschakov as a modest homage to his monographic publications, especially those regarding the Okhotsk Sea fauna, and by his other numerous publications on polychaetes. The epithet is a noun in the genitive case.
The introvert is markedly swollen, like in the holotype, in one paratype and in some non-type specimens. Introvert chaetigers with 9–10 hooks per bundle. The ventro-caudal shield is dirty orange to pale brick red, ribs and concentric lines are always visible but variably developed; anterior margins rounded to barely acute (
Okhotsk Sea in 592–1366 m, California in 1585 m, Gulf of California in 1200–1274 m, and off Western Mexico in 2548 m, in mud or muddy sands.
Holotype (LACM 5353) with body brownish, paler over remaining integument with papillae (
Prostomium small ovoid, paler distally, darker basally (
First three chaetigers with 12–14 bronze, slightly falcate hooks per bundle, each with subdistal dark areas. Genital papillae lost, eroded from the intersegmental groove between segments 7 and 8 (not visible in paratypes either).
Pre-shield region with 7 segments, with papillae abundant in protected areas (some paratypes with papillae arranged in single transverse series per segment). Short, few capillary chaetae present in one segment (in up to three segments in paratypes).
Ventro-caudal shield pale orange (
Marginal chaetal fascicles include 10 lateral ones; chaetae ovally arranged, and 5 posterior fascicles (6–7 in paratypes). Peg chaetae or associated capillaries not visible (neither in paratypes).
Branchiae lost in holotype (paratypes with abundant filaments, some 2–3 times thicker, and half as long as the others). Branchial plates parallel, anteriorly rounded.
There are several modifications in the shield development with roughly defined ribs and the general outline has lateral margins rounded, medially expanded, some distortions were noticed probably due to sample handling since the body is rather delicate. The shield pigmentations is dark yellow in smaller paratypes (
Very small juveniles show a transition in pigmentation and development of the ventro-caudal shield (
This species is named after Susan Williams, in recognition of her taxonomic work on trichobranchids, and because she left some notes indicating that she regarded some of the materials herein included for this description as representing a different pattern which deserved a name. The epithet is a noun in the genitive case.
W off Yaquina Bay, Oregon, 2800 m depth.
Only known from Oregon to California, 1000–2800 m depth.
(Modified after
1 | Ventro-caudal shield’s fan with a distinct median notch | 2 |
– | Ventro-caudal shield’s fan continuous, without a distinct median notch | 9 |
2(1) | Shield with radial ribs and concentric lines distinct | 3 |
– | Shield with radial ribs distinct, concentric lines barely visible | 7 |
3(2) | Fan with median notch shallow | 4 |
– | Fan with median notch deep; shields usually with concentric bands | 5 |
4(3) | Shield with distinct concentric bands; main rib and posterior corners directed posteriorly | |
– | Shield without concentric bands; posterior corners directed laterally | |
5(3) | Shield with posterior corners distinct | |
– | Shield with posterior corners poorly-defined | 6 |
6(5) | Introvert and body with similar pigmentation or introvert paler; shield widest medially | |
– | Introvert and body with different pigmentation, introvert darker; shield widest anteriorly | |
7(2) | Main ribs markedly divergent; fan as wide as anterior margins or wider | |
– | Main ribs moderately divergent; fan half as wide as anterior margins | 8 |
8(7) | Posterior margin truncate, with lateral notches; ribs well-developed | |
– | Posterior margin with a median notch, lateral notches shallow or indistinct; ribs poorly developed | |
9(1) | Fan margin crenulated, not projected posteriorly | 10 |
– | Fan margin denticulate, medially projected | 14 |
10(9) | Shield with ribs and concentric lines | 11 |
– | Shield with ribs; concentric lines indistinct | |
11(10) | Shield anterior margins rounded | 12 |
– | Shield anterior margins acute | |
12(11) | Shield with posterior corners distinct | 13 |
– | Shield with posterior corners indistinct | |
13(12) | Posterior corners barely projected beyond fan margin; introvert hooks thick, bronze | |
– | Posterior corners projected beyond fan margin; introvert hooks thin, golden | |
14(9) | Fan without lateral notches; body papillae arranged in distinct transverse rows | |
– | Fan with lateral notches; body papillae distributed homogeneously, not arranged in transverse rows | 15 |
15(14) | Introvert with about 15 pale hooks per bundle | |
– | Introvert with about 10 dark hooks per bundle |
This research was supported by the Zoological Institute, Russian Academy of Sciences, the Dynasty Foundation, Moscow, Muséum National d’Histoire Naturelle, Paris, ECOSUR and CONACYT (sabbatical scholarship to SISV). The director of the Zoological Institute, Dr Oleg Pugachev allowed the senior author to be housed in the Academy of Sciences hotel, and the local staff was very kind and helpful during our stay. Drs Anna Zhadan and Nataliya Budaeva made his visit to Moscow very pleasant and productive. Dr Danny Eibye-Jacobsen kindly sent some specimens from their collections to Paris, and Dr Tarik Meziane was very helpful for my visit to MNHN. Dr Eugenia Labina from the Zoological Institute Library helped finding some publications and Dr Anja Schulze kindly sent a difficult to find publication about the R.V. Anton Bruun SE Pacific Expedition. The visits to CAS was easy thanks to Chrissy Piotrowski, to LACM by the generous support of Leslie Harris and David Ocker, and to UNAM in Mazatlán by Drs María Ana Tovar-Hernández, Beatriz Yáñez and Nuri Méndez. The careful reading by Dr Brigitte Hilbig and an anonymous reviewer resulted in a much improved document.