Prionospio steenstrupi Malmgren, 1867

Hektoen, Martin M., Radashevsky, Vasily I. & Bakken, Torkild, 2025, Partial revision of northern European Prionospio Malmgren, 1867 (Annelida: Spionidae), European Journal of Taxonomy 1027, pp. 1-58 : 45-49

Prionospio steenstrupi Malmgren, 1867

Fig. 21; Table 2

Prionospio steenstrupi Malmgren, 1867: 201–202 , pl. 10 fig. 55.

Prionospio steenstrupi – Wesenberg-Lund 1951: 70. — Sigvaldadóttir & Mackie 1993: 204–207, figs 1–2. — Sigvaldadóttir 2002: 213–214.

Prionospio ( Prionospio) steenstrupi – Maciolek 1985: 332 (partim).

Non Prionospio steenstrupi – Söderström 1920: 232–233, figs 136–140. — Day 1963: 418; 1967: 489, fig. 18.9o–j. — Blake & Kudenov 1978: 213, fig. 20a.

Non Prionospio ( Prionospio) steenstrupi – Blake 1996: 123–125, fig. 9. — Dagli & Çinar 2009: 12–13 .

Diagnosis

Prostomium anteriorly truncate, posteriorly extending to end of chaetiger 2 as a narrow caruncle. Four pairs of branchiae on chaetigers 2–5; those of chaetigers 2 and 5 long, pinnate, branchiae of chaetigers 3 and 4 short, apinnate. Dorsal crests from chaetiger 6 to chaetigers 16–18, slightly higher on chaetiger 7. Membranous folds between notopodia on chaetigers 4–13. Neuropodial postchaetal lamellae of chaetiger 2 subrectangular with acute ventral point. Sabre chaetae in neuropodia from chaetiger 10. Hooded hooks in notopodia from chaetigers 43–58, in neuropodia from chaetigers 15–17.

Type material

Lectotype

ICELAND • Skagafjördur , Hofsås; 65°54.000′ N, 19°25.000′ W; depth 73 m; stn IcelandMalm; designated by Sigvaldadóttir & Mackie (1993); SMNH Type-3170.

Paralectotypes

ICELAND • 4 specs. Skagafjördur , Hofsås; 65°54.000′ N, 19°25.000′ W; depth 73 m; stn IcelandMalm; designated by Sigvaldadóttir & Mackie (1993); SMNH Type-3170 .

Other material examined

ICELAND • 13 specs; Eyiafjordur , Akureyri; 21 Mar. 1972; S. Ingvarsson leg.; stn akureypollur 1972; SMNH 174654 • 30 specs; Reydarfjördur ; 66°22.000′ N, 13°57.000′ W; depth 127 m; 13 Jul. 1980; J. Svavarsson det.; stn R-2; SMNH 174656 • 10 specs; Reydarfjördur ; 66°1.000′ N, 14°9.083′ W; depth 87 m; 13 Jul. 1980; J. Svavarsson leg.; stn R-1; SMNH 174655 • 20 specs; Reydarfjördur ; 64°59.117′ N, 13°50.117′ W; depth 160 m; 13 Jul. 1980; stn R-3; SMNH 174657 .

Comparative material

Prionospio cf. steenstrupi

UNITED STATES – Massachusetts • 5 specs; Cape Cod Bay , between Combination Buoy and Ellisville; depth 20 m; 17 Jun. 1954; M. Pettibone leg; USNM 34200 • 7 specs; same data as for preceding; USNM 34203 • 2 specs; Cape Cod Bay , 0.5 mile E and 2 mile N of Combination Buoy; depth 20–22 m; 9 Aug. 1954; M. Pettibone leg.; USNM 34193 • 1 spec.; 0.75 mile South Vineyard Sound Lightship ; depth 29 m; 4 Aug. 1953; M. Pettibone leg.; USNM 34204 .

CANADA – Quebec • 27 specs; Gaspe Peninsula, Gaspe Bay , NW of Gaspe Harbor; depth 13 m; 14 Jul. 1959; P. Brunel leg.; USNM 34194 • 15 specs; Gaspe Bay, Mouth of Gaspe Bay , SE of Gape Gaspe; depth 102 m; 15 Jul. 1959; P. Brunel leg.; USNM 34197 • 10 specs; Gaspe Peninsula, Bay of Chaleur, Miscou Bank ; 48°44′ N, 64°11′ W; depth 60 m; 30 Aug. 1953; P. Brunel leg.; stn HEC 216; USNM 34198 • 5 specs; same data as for preceding; USNM 34199 . – New Brunswick • 5 specs; Bay of Chaleur, Nipissiquit Bay ; depth 37 m; 20 Jul. 1956; P. Brunel leg.; USNM 34201 • 5 specs; same data as for preceding; USNM 34195 .

Remarks

The original description of P. steenstrupi from Iceland by Malmgren (1867) was brief and imprecise. Since then, the species has been reported from the Pacific and Atlantic coasts of the United States (e.g., Foster 1971), South Africa ( Day 1967), Australia ( Blake & Kudenov 1978), the Sea of Japan ( Uschakov 1955), Brazil ( Bolivar & Lana 1987), and Chile ( Blake 1983). However, the conspecificity of the distant populations has never been verified by molecular data and such data from Icelandic specimens are absent.

In the Northeast Atlantic, species of the P. steenstrupi group were weakly delineated until the end of the 20 th century. Sigvaldadóttir & Mackie (1993) re-examined the type specimens, designated a lectotype and clarified the morphology of P. steenstrupi using additional material from Iceland. They noted that P. steenstrupi could only be proven to occur around Iceland, and all other records of this species require re-evaluation.

We examined the type and additional material of P. steenstrupi from Iceland reported by Sigvaldadóttir & Mackie (1993). The redescription provided by the authors is detailed and comprehensive, and we found no significant deviations from their findings. As such, a full redescription was deemed unnecessary. Thus, we only provide additional notes on the species. The dorsolateral membranous folds between notopodia ( Fig. 21B) were present in all specimens studied, at the very least visible as remnants. These folds have not been reported for any other species of Prionospio (see comments below on P. steenstrupi from Turkey reported by Dagli & Çinar 2009). We also examined specimens from the Atlantic and Pacific coasts of the US identified as P. steenstrupi and stored in the Smithsonian National Museum of National History, Washington, D.C. Most of these specimens morphologically differed from Icelandic specimens. However, one series of lots identified by Marian Pettibone from the Northeast US coast and East Canadian coast (USNM 34193–34205) contained specimens with dorsolateral membranous folds like P. steenstrupi . The only difference between these and the Icelandic specimens was that some West Atlantic specimens had sabre chaetae in neuropodia from chaetiger 11 rather than chaetiger 10 as in all Icelandic specimens. The conspecificity of these specimens requires further study.

Prionospio steenstrupi has been predominantly reported in Iceland since its morphology was clarified by Sigvaldadóttir & Mackie (1993), with no peer-reviewed reports corroborating its presence in European Atlantic waters outside of Iceland. However, ecological surveys over the last two decades reported common occurrences of this species in Norwegian waters (https://www.artsdatabanken.no accessed 20 Aug. 2023). Our examination of specimens collected in these surveys showed a great number of misidentifications. Worms identified as P. steenstrupi from Norwegian coastal waters actually belonged either to P. fallax or P. plumosa , while the offshore worms are here referred to P. sigvaldadottirae sp. nov. (see remarks on P. sigvaldadottirae above). No evidence has been found to support the presence of P. steenstrupi in the coastal or shelf waters of mainland Europe, suggesting that the species, if present, is rare in this region.

Dagli & Çinar (2009) reported P. steenstrupi from the Eastern Mediterranean, Turkey, with dorsolateral membranous folds as in the Icelandic specimens. However, the Turkish specimens had dorsal crests from chaetiger 7 (rather than from chaetiger 6) and caruncle reaching the end of chaetiger 1 (rather than the end of chaetiger 2) and might represent a yet undescribed species.

Habitats and distribution

Prionospio steenstrupi is only known from Iceland, between 73 and 160 m depth.