Streblospio Webster, 1879

Delgado-Blas, Víctor Hugo, Díaz-Díaz, Óscar & Viéitez, José M., 2018, New species of Dispio Hartman, 1951 and Streblospio Webster, 1879 (Polychaeta, Spionidae) from the coast of the Iberian Peninsula, Zootaxa 4410 (3), pp. 525-538 : 534

Streblospio Webster, 1879

Type species: Streblospio benedicti Webster, 1879 .

Diagnosis. Prostomium oval, fusiform or conical; anteriorly rounded and posteriorly tapered extending to anterior margin of chaetiger 1; 2–4 pairs of eyes or eyes absent; small tentacle or papilla on the dorsum of chaetiger 1 between branchiae; peristomium fused with the first chaetiger, forming short lateral wings enclosing the prostomium; one pair of palps densely ciliated on frontal surface, palp sheaths absent; one pair of branchiae present on chaetiger 1; chaetiger 1 with notopodial postchaetal lamellae absent and capillary notochaetae scarce or absent; entire or bilobed dorsal membranous collar across the dorsum of chaetiger 2; notopodial and neuropodial postchaetal lamellae small, oval, rounded, or flap-like on anterior chaetigers, and digitiform or highly reduced or absent on posterior chaetigers; all notopodial chaetae capillary; neuropodial chaetae include capillaries, multidentate hooded hooks first appearing on chaetigers 6–9, and sabre chaetae beginning on chaetigers 3–7; notopodial hooks absent; pygidium simple or lobed, with or without ventral lappets, cirri absent.

Remarks. Imajima (1990) described Streblospio benedicti japonica as a new subspecies from Japan after comparing his specimens with the description of S. benedicti Webster, 1879 . Imajima (1990) distinguished S. benedicti japonica from S. benedicti based on the fact that the former has neuropodial hooks with five pairs of accessory teeth, and sabre chaetae beginning on chaetiger 3, whereas the latter has hooks with 3–4 pairs of accessory teeth, and sabre chaetae beginning on chaetiger 7. In addition, S. benedicti japonica has fewer segments (48 vs. 70) than S. benedicti , and a pygidium with two lappets, whereas in S. benedicti the pygidium is simple or lobed. We propose that these character differences are sufficient to consider the subspecies as a distinct species, and we thus suggest raising the status of S. benedicti japonica Imajima, 1990 to full species level as S. japonica Imajima, 1990 .

One aspect to consider is the term nuchal papilla. We believe that this term is unsuitable, as when present, this papilla is not in a nuchal position: it is not located in the posterior and inferior region of the prostomium, but rather dorsally on the first chaetiger between the two branchiae.