Prionospio cf. ehlersi Fauvel, 1928

elgado-Blas, Victor Hugo, iaz-Diaz, Oscar & ieitez, Jose M., 2018, Prionospio from the coast of the Iberian Peninsula, with the description of two new species (Annelida, Spionidae), ZooKeys 810, pp. 1-18 : 3-4

Prionospio cf. ehlersi Fauvel, 1928 Figure 2 A–R

Material examined.

Atlantic Ocean. Galicia: 4 specimens (MNCNM 16.01/18424), Ría de Arousa, La Coruña, GA EBS 250, VERTIDOS 04, 42°36'23"N, 8°53'20"W, 26 September 2004, coll. J Parapar; 6 specimens (MNCNM 16.01/18425), GA EBS 200, VERTIDOS 04, 42°36'22"N, 8°52'20"W, 26 September 2004, coll. J Parapar; 17 specimens (MNCNM 16.01/18426), shelf and upper slope off the Artabro Gulf: GA AT 110-4, 43°29'15"N, 8°28'41"W, 25 September 2004, coll. J Parapar; 1 specimen (MNCNM 16.01/18427), DIVA-Artabria 2003: EBS 250, 43°40'14"N, 8°44'3"W, 12 September 2003, coll. J Parapar; 3 specimens (MNCNM 16.01/18428), EBS 1 200E, 43°43'40"N, 8°36'49"W, 12 September 2003, coll. J Parapar; 2 specimens (MNCNM 16.01/18429), EBS 200, 43°43'40"N, 8°36'49"W, 12 September 2003, coll. J Parapar; 25 specimens (MNCNM 16.01/18430), EBS 200, 43°43'40"N, 8°36'49"W, 12 September 2003, coll. J Parapar; 23 specimens (MNCNM 16.01/18431), EB5 200, 43°43'40"N, 8°36'49"W; 3 specimens (MNCNM 16.01/18432), EBS 150 W, 43°31'36"N, 8°43'56"W; 14 September 2003, coll. J Parapar.

Description.

Incomplete specimens, 3.0-11.0 mm long, with 13-40 chaetigers, 0.6-1.0 mm wide. Posterior fragment 9.0 mm long for 26 chaetigers, 0.8 mm wide. Color in alcohol pale white. Some specimens with oocytes on chaetigers XXX–XXXIV.

Prostomium bottle-shaped, rounded anteriorly (Fig. 2A, A', B), posteriorly tapered, with short, narrow caruncle extending to anterior edge of chaetiger II; caruncle with large triangular nuchal organs on either side (Fig. 2A', B). Two pairs of black subdermal eyes, arranged in a trapezoid; anterior pair small, rounded, posterior pair small, crescent-shaped; one paratype without eyes (Fig. 2A, A', B). Palps lost, except in one specimen with palps inserted anterior to nuchal organs: left palp in process of regeneration, with a short basal sheath (Fig. 2C). Peristomium short, collar-like, surrounding prostomium, partially fused dorsally with very large oval notopodial lamellae on chaetiger I (Fig. 2A, B). Neuropodial postchaetal lamellae on chaetiger I small, rounded (Fig. 2A, A', B), smaller than notopodial lamellae. Eversible, sac-like proboscis.

Four pairs of branchiae present on chaetigers II–V, first pair longest and thickest (Fig. 2D); sometimes first and fourth pairs equal in length or fourth pair slightly longer than first. First pair with long, dense digitiform pinnules on lateral and posterior faces, continuing to tip; central stem of branchial pair 1 pinnate, cylindrical, very thick and with a blunt tip (Fig. 2A, D). Pairs 2-4 apinnate; pairs 2 and 3 triangular, thick (Fig. 2D, E), slightly expanded distally, with rounded tips, densely ciliated laterally, shorter than notopodial lamellae and pinnate pair. Pair 4 cirriform (Fig. 2D), basally united by a short, moderate dorsal cord-shape (Fig. 2D); branchiae subequal to, or longer than, notopodial lamellae; some specimens with regenerating branchiae.

Notopodial postchaetal lamellae subtriangular, short on chaetiger II (Fig. 2A, B, D); lamellae on chaetigers III–VII triangular with wide bases (Fig. 2A, B, D); larger and wider on chaetigers III– IV, with long, triangular tips (Fig. 2A, B, E) (in some specimens, the notopodial lamellae on chaetigers III–IV touch each other). Lamellae gradually becoming smaller, rounder and more dorsally directed on chaetiger VIII (Fig. 2F); lamellae on chaetiger XIX subtriangular and becoming angular with ventrally-directed process. Subsequent lamellae progressively decreasing in size, and becoming rounded and wider with ventrally pointed edges (Fig. 2G). Lamellae on posterior chaetigers oval. Notopodial postchaetal lamellae united across dorsum, forming a low dorsal crest, starting on chaetiger VI (Fig. 2D) and continuing as a very low fold or large crest (in large specimens) (Fig. 2H) up to almost end of body. Ventral and dorsal edges of notopodial and neuropodial lamellae touching or overlapping (Fig. 2I) from chaetigers VII–X, up to about chaetiger XX. Anterior notopodial prechaetal lamellae low, rounded; posterior lamellae rudimentary.

Anterior neuropodial postchaetal lamellae large, rounded on chaetiger II (Fig. 2B); very large, more angular and dorsally directed on chaetiger III (Fig. 2E); oval on chaetigers IV–XV (Fig. 2J); subsequent neuropodial lamellae small, rounded up to end of body. Neuropodial prechaetal lamellae low in branchial region (Fig. 2F, J), thereafter increasing in size; some specimens with small ventral rounded lobe like extensions of neuropodial prechaetal lamellae on middle chaetigers, rudimentary on posterior chaetigers. Interparapodial pouches (Fig. 2I) from chaetigers IV–V up to end of fragments, non-reticulated; interparapodial pouches fused with neuropodial prechaetal lamellae.

Notopodial capillaries on chaetigers I–II arranged in two rows, with short, slender, slightly granulated and unilimbate chaetae (Fig. 2K); posterior row longer than anterior one. Notopodial capillaries on chaetigers III–XIII arranged in three rows, anterior row shortest; dorsal chaetae very long and acute (Fig. 2L), ventral chaetae very short and acute; capillaries on middle chaetigers smooth, unilimbate (Fig. 2M); posterior capillaries long, smooth, alimbate (Fig. 2N). Anterior neuropodial chaetigers with granulated, unilimbate capillaries arranged in two rows, anterior row much shorter than the posterior one; capillaries on middle chaetigers slightly granulated, alimbate (Fig. 2O); capillaries on posterior chaetigers smooth, alimbate. Neuropodial sabre chaetae from chaetigers XVII–XX up to two per parapodium, each chaeta long, stout, heavily granulated, alimbate (Fig. 2P). Neuropodial hooded hooks (Fig. 2Q) from chaetigers XVIII–XX, up to 15 per fascicle; notopodial hooded hooks not observed up to chaetiger XL (present in a posterior fragment up to 10 per fascicle); hooks with six pairs of small teeth (Fig. 2Q) above thick, blunt main tooth, and a large principal hood; hooks also appear to possess very striated secondary hoods, producing a feathered effect below main tooth (Fig. 2Q).

Pygidium with one long median cirrus and two short, rounded, lateral lobes (Fig. 2R).

Remarks.

Prionospio cf. ehlersi is very similar to the original and subsequent descriptions of P. ehlersi ( Fauvel 1928, Mackie and Hartley 1990), in that both describe the same prostomial shape, branchial arrangement, and hooded hook structure, and all have interparapodial pouches. However, specimens of this study differ from P. ehlersi in that the former have oval (rather than triangular to subtriangular) notopodial lamellae on chaetiger I, the neuropodial lamellae on chaetigers IV–V are oval (rather than rounded), and the second and third branchial pairs are triangular and thick (rather than expanded or swollen distally), a dorsal cord-shape (rather than low crest) on chaetiger V is present, and the sabre chaetae in P. cf. ehlersi are alimbate (rather than sheathed). Mackie and Hartley (1990) reported a variation in the shape of chaetiger I notopodial postchaetal lamellae, and so considered this unimportant. They also noted some parapodial variation around chaetiger XVIII–XX. They did not mention the oval anterior neuropodial postchaetal lamellae, however, Fauvel (1928, fig. 1b) shows a chaetiger IV with neuropodial lamella very similar to that in this study (Fig. 2J). We consider that these differences are important, but we consider it premature to erect a new species with these specimens, without being able to first compare them with Fauvel’s syntype material. The syntypes are deposited at the Museum National d’Histoire Naturelle, Paris under MNHN A438, A449. However, the material cannot be sent abroad for re-examination.

Type locality.

Ría de Arousa (La Coruña, Galicia, Spain).

Distribution.

Atlantic Ocean. Galicia: Ría de Arousa, La Coruña, shelf and upper slope off the Artabro Gulf, Spain.