Prionospio sanmartini Delgado-Blas, Díaz-Díaz & Viéitez, 2019

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 : 24-29

Prionospio sanmartini Delgado-Blas, Díaz-Díaz & Viéitez, 2019

Figs 9–11

Prionospio ( Minuspio) sanmartini Delgado-Blas, Díaz-Díaz & Viéitez, 2019: 568–573 , fig. 3, table 1. Prionospio ( Minuspio) multibranchiata – Mackie 1984: 40–42, fig. 3, table 2.

Prionospio multibranchiata – Kirkegaard 1996: 84–85, fig. 38.

Prionospio ( Minuspio) cirrifera – Hartmann-Schröder 1996: 329–330 (partim).

Prionospio cf. sanmartini – Hektoen et al. 2024: figs 1, 4.

Diagnosis

Prostomium narrow, anteriorly rounded, posteriorly extending to middle of chaetiger 2 as a narrow caruncle. Two pairs of eyes present; median eyes single or multiple spots sometimes fused together. Eight to 13 pairs of apinnate branchiae from chaetiger 2. Low dorsal crests from chaetigers 12–14. Neuropodial postchaetal lamellae of chaetiger 2 not elongated ventrally. Sabre chaetae in neuropodia from chaetigers 12–17. Hooded hooks in notopodia from chaetigers 35–41, in neuropodia from chaetigers 13–19.

Type material

Paratypes

SPAIN • 9 specs; Galicia, Ría de Foz ; 43°33′ N, 7°15′ W; J. Junoy leg.; stn CC1. XII.85; MNCN 16.01 /18448 .

Other material examined

FRANCE • 20 specs; Banyuls sur Mer ; 42°30.000′ N, 3°9.000′ E; depth 4 m; F. Pleijel leg.; stn Banyuls 1; van Veen grab; SMNH 111901 • 3 specs; Banyuls sur Mer ; 42°29.000′ N, 3°9.000′ E; depth 32 m; F. Pleijel leg.; stn Banyuls 2; van Veen grab; SMNH 111903 .

ITALY • 11 specs; Sicily, Brucoli ; 37°17.000′ N, 15°11.000′ E; depth 40 m; 1990; Mission Sicile Orientale 1990 leg.; stn Sicily 1 1990; van Veen grab; SMNH 111895 .

NORWAY – Vestfold • 3 specs; Larvik, Larviksfjorden ; 59°2.667′ N, 10°1.537′ E; depth 43 m; 2020; NIVA leg.; stn LAR-S27; van Veen grab; NTNU-VM 84121 • 1 spec.; Sandefjord ; 59°0.786′ N, 10°22.301′ E; depth 57 m; 2019; NIVA leg.; stn A05/BT40; van Veen grab; NTNU-VM 84118 • 8 specs; Larvik, Stavern ; 58°59.815′ N, 10°2.710′ E; depth 13 m; 2020; NIVA leg.; stn STA-1; van Veen grab; NTNU-VM 84119 . – Telemark • 7 specs; Porsgrunn ; 59°3.220′ N, 9°45.069′ E; depth 31 m; 2018; NIVA leg.; stn F04-C; van Veen grab; NTNU-VM 84122 . – Agder • 6 specs; Kristiansand, Skoltebukta ; 58°7.503′ N, 7°58.788′ E; depth 31 m; 2020; NIVA leg.; stn K17; van Veen grab; NTNU-VM 84116 • 18 specs; Kristiansand, Skoltebukta ; 58°7.465′ N, 7°58.472′ E; depth 20 m; 2020; NIVA leg.; stn EC1; van Veen grab; NTNU-VM 84117 • 3 specs; Kristiansand, Skoltebukta ; 58°7.161′ N, 7°58.661′ E; depth 17 m; 2020; NIVA leg.; stn KH03; van Veen grab; NTNU-VM. 84120 .

SWEDEN – Bohuslän • 1 spec.; Strömstad, Tjärnö ; 58°52.860′ N, 11°6.480′ E; 2019; A. Nygren leg.; stn KAU-02; van Veen grab; NTNU-VM 84124 • 5 specs; Tanum, Väderöarna ; depth 118 m; 1985; stn Väderöarna 2; van Veen grab; SMNH 111879 • 4 specs; Tanum, Väderöarna ; depth 40 m; 1984; van Veen grab; SMNH 111880 . – Halland • 2; Varberg, Värö ; 57°10.000′ N, 12°5.000′ E; depth 20 m; 1978; stn VÄRV78#2; van Veen grab; SMNH 6442 • 50 specs; Varberg, Värö ; 57°10.000′ N, 12°1.000′ E; depth 47 m; 1978; stn VÄRV78#3; van Veen grab; SMNH 6452 • 100 specs; Varberg, Värö ; 57°10.000′ N, 12°1.000′ E; depth 47 m; 1979; stn VÄRV79#3; van Veen grab; SMNH 8706 • 50 specs.; Varberg, Värö ; 57°10.000′ N, 12°1.000′ E; depth 47 m; 1980; stn VÄRV80#3; van Veen grab; SMNH 9630 • 50 specs; Varberg, Värö ; 57°16.000′ N, 12°5.000′ E; depth 19 m; 1980; stn VÄRV80#7; van Veen grab; SMNH 10104 • 2 specs; Varberg, Värö ; 57°13.000′ N, 12°4.000′ E; depth 21 m; 1984; stn VÄRH84#1; van Veen grab; SMNH 52762 • 4 specs; Varberg, Värö ; 57°16.000′ N, 12°5.000′ E; depth 19 m; 1984; stn VÄRV84#7; van Veen grab; SMNH 53618 • 12 specs; Varberg, Värö ; 57°10.000′ N, 12°1.000′ E; depth 47 m; 1984; stn VÄRV84#3; van Veen grab; SMNH 53677 • 5 specs; Varberg, Värö ; 57°13.000′ N, 12°1.000′ E; depth 39 m; 1984; stn VÄRH84#4; van Veen grab; SMNH 53565 • 5 specs; Varberg, Värö ; 57°13.000′ N, 12°4.000′ E; depth 21 m; 1987; stn VÄRV87#1; van Veen grab; SMNH 54729 • 5 specs; Varberg, Värö ; 57°8.000′ N, 12°6.000′ E; depth 22 m; 1984; stn VÄRV84#8; van Veen grab; SMNH 53644 • 1 spec.; Varberg, Värö ; 57°16.000′ N, 12°5.000′ E; depth 19 m; 1981; stn VÄRH81#7; van Veen grab; SMNH 11433 • 25 specs; Varberg, Värö ; 57°10.000′ N, 12°1.000′ E; depth 47 m; 1987; stn VÄRV87#3; van Veen grab; SMNH 67943 .

UNITED KINGDOM • 5 specs; Loch Creran ; depth 25 m; 1978; A. Mackie leg.; stn Loch Creran 2; van Veen grab; SMNH 178632 • 5 specs; same data as for preceding; USNM; 80865 .

Examined material with sequence data

SWEDEN – Bohuslän • 1 spec.; Strömstad, Tjärnö; 58°52.860′ N, 11°6.480′ E; 2019; A. Nygren leg.; stn KAU-02; van Veen grab; NTNU-VM 84123 • 1 spec.; same data as for preceding; SEM stub; NTNU-VM 84140 .

Description (adults)

Largest complete specimen 35 mm long, 0.4 mm wide for 72 chaetigers; largest anterior fragment 0.5 mm wide. Color in alcohol brownish to pale white. Prostomium narrow, widest in front of lateral eyes ( Fig. 9A–C), anteriorly rounded, posteriorly extending to middle of chaetiger 2 as narrow caruncle. Nuchal organs U-shaped ciliary bands lateral to caruncle ( Fig. 9A). Most specimens with two pairs of eyes arranged trapezoidally; median eyes multiple small spots, often fused together forming crescent; lateral eyes single round spots ( Fig. 9B). Posterior dorsolateral parts of peristomium fused with notopodial postchaetal lamellae of chaetiger 1 forming ear-shaped structures lateral to prostomium. Palps missing in all specimens.

Branchiae from chaetiger 2 to chaetigers 9–14 (usually to chaetigers 10–14) ( Figs 9A–C, 10A), cirriform, apinnate with lateral ciliation. First pair of branchiae usually longest, up to 2 × as long as notopodial lamellae; last pair usually shortest; remaining branchiae similar to each other and equal to or slightly longer than notopodial postchaetal lamellae ( Figs 9A–C, 10A, 11B–I). Nototrochs transverse ciliary bands between branchial bases. Dorsolateral longitudinal ciliation absent.

Notopodial prechaetal lamellae small, rounded in anterior region, reduced in posterior part of body. Notopodial postchaetal lamellae of chaetiger 1 broadly rounded, fused with peristomium ( Fig. 11A). Lamellae of chaetigers 2–12 subtriangular, largest on chaetigers 3–10 ( Fig. 11B–H), lower and rounded on postbranchial chaetigers ( Fig. 11I–J). Notopodial postchaetal lamellae joined across dorsum forming low transverse crests from chaetigers 12–14 to chaetigers 27–34 ( Figs 9–10). Neuropodial prechaetal lamellae inconspicuous. Neuropodial postchaetal lamellae of chaetiger 1 small, oblong, rounded; lamellae of chaetiger 2 rectangular, wider than long, not pointing ventrally; on chaetiger 3 longer than wide; from chaetiger 4, lamellae evenly rounded, almost circular by chaetiger 15 ( Fig. 11A–J), reduced on succeeding chaetigers. Interneuropodial pouches absent.

Notopodial capillaries on anterior and middle chaetigers arranged in two rows, unilimbate, slightly granulated; anterior row shorter than posterior row. Notopodial capillaries on posterior chaetigers alimbate, long, thin. Neuropodial capillaries arranged in two rows on anterior chaetigers, unilimbate, slightly granulated, anterior row shorter than posterior row. Sabre chaetae in neuropodia from chaetigers 12–17, with granulation on distal part of shaft, up to two per fascicle ( Fig. 10B). Hooded hooks in notopodia from chaetigers 35–41. Hooks in neuropodia from chaetigers 13–19, up to eight per ramus, alternating with capillary chaetae. Both noto- and neuropodial hooded hooks with 4–5 pairs of upper teeth arranged in two vertical rows above main fang, with outer and small inner hoods ( Fig. 11K).

Pygidium with one long middorsal cirrus and a pair of short ventral cirri.

Remarks

Prionospio with more than six pairs of smooth apinnate branchiae from the Northeast Atlantic have historically been attributed to P. multibranchiata (e.g., Mackie 1984). In the last 15 years, such worms from the Levantine Sea ( Turkey) were described as P. maciolekae Dagli & Çinar, 2011 , and worms from the Atlantic coast of Spain were described as P. sanmartini Delgado-Blas, Díaz-Díaz & Viéitez, 2019 . Delgado-Blas et al. (2019) provided an updated description of P. multibranchiata based on specimens from Vancouver ( British Columbia, Canada), but did not study the type material of this species. The authors distinguished P. sanmartini from the description of northern European specimens previously described and identified as P. multibranchiata by Mackie (1984); however, they did not study material described by Mackie (1984). Prionospio sanmartini and P. multibranchiata sensu Mackie (1984) were distinguished based on the shape of the prostomium, size and shape of the eyes, and shape of the neuropodial postchaetal lamellae of chaetiger 2 ( Delgado-Blas et al. 2019). However, our study of new material from Skagerrak, specimens from Scotland examined and described by Mackie (1984), as well as other specimens identified by Mackie and present in the Swedish Natural History Museum from Italy, France, and Sweden, and paratypes of P. sanmartini , showed that differences between them can be interpreted as either individual or ontogenetic variability of one species. The prostomium is rounded both in paratypes of P. sanmartini and the other specimens ( Fig. 9A–C). Both paratypes of P. sanmartini and the other specimens have eyes of varying sizes and shapes (from single points to crescentic). Similarly, there was no significant difference between the shape of the neuropodial postchaetal lamellae of chaetiger 2. Hektoen et al. (2024) showed that specimens from the Swedish west coast were genetically similar to one specimen from northern Spain, close to the type locality of P. sanmartini , indicating the existence of an extended population of one species, rather than geographically separated two species. Thus, we consider P. sanmartini to also occur in Skagerrak waters in Norway and Sweden.

We found some differences between the paratypes of P. sanmartini and northern European specimens of similar sizes: the number of branchiae (10 pairs in the P. sanmartini paratypes and usually 10–13 pairs in specimens of similarly size from northern Europe), distribution of dorsal crests (on chaetigers 12–18 in P. sanmartini and from chaetigers 13–14 on more than 15 succeeding chaetigers in northern European specimens), and start of sabre chaetae (from chaetigers 12–16 in P. sanmartini and 14–17 in northern European specimens). However, we do not find this evidence sufficient to separate northern and southern European populations and consider them conspecific, especially considering the genetic evidence for an extended geographical distribution of one species. The holotype of P. sanmartini was not available for this study.

Habitats and distribution

Prionospio sanmartini is known from fine-grained sediments between 4 and 118 m depth in southern Norway, the West coast of Sweden, Scotland, France, Spain, and Italy.