Dispio elegans Delgado-Blas & Díaz-Díaz & Viéitez 2018, sp. nov.
Creators: name: Delgado-Blas, Víctor Hugo
name: Díaz-Díaz, Óscar
name: Viéitez, José M.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Spionida
Spionidae
Dispio
Dispio elegans

description: Dispio elegans sp. nov.
Figure 2A–Z
Dispio uncinata: Viéitez, 1981; Laborda & Viéitez, 1984; Junoy et al., 2005.
Type material. Atlantic coast: Meira beach, Ría de Vigo, 41°17′N, 08°43′W, intertidal holotype (MNCNM 16.01/ 17913) and 11 paratypes (MNCNM 16.01/17915) (Col. J.M. Viéitez); Louro beach, A Coruña, 1 paratype, 42°44′N, 9°03′W, intertidal (MNCNM 16.01/17914) (Col. C. Castellanos & J. Junoy). NE Atlantic: Cantabrian coast. Off Zarautz, Bay of Biscay, 43°17′N, 2°10′W, 7–15 m depth, 67 paratypes (MNCNM 16.01/17921–17934) (Col. F. Aguirrezabalaga); Covas beach, Lugo, 43°40′N, 7°36′W, intertidal, 6 paratypes (MNCNM 16.01/17916– 17920) (Col. A. Laborda).
Non-type material. NE Atlantic: Cantabrian coast. San Román beach, Lugo, 43°44ʹN, 7° 39′W, intertidal, 1 specimen, (MNCNM 16.01/17935) (Col. C. Castellanos & J. Junoy); Esteiro beach, Lugo, 43°32ʹN, 7°33ʹW, intertidal, 1 specimen (MNCNM 16.01/17936) (Col. C. Castellanos & J. Junoy).
Description. Holotype incomplete, 16 mm long with 47 chaetigers, 1.5 mm wide at chaetiger 15. Colour in alcohol opaque off-white. Paratypes incomplete, 26–53 mm long, 45–85 chaetigers, 2.6–3.7 mm wide at chaetiger 15. Colour in alcohol light beige. No other pigmentation present.
Prostomium oblanceolate, pointed anteriorly (Fig. 2A), posteriorly tapered with a long, narrow caruncle observed as a longitudinally long nuchal ridge, extending to the anterior margin of chaetiger 2 (Fig. 2A). One pair of rounded, black subdermal eyes (Fig. 2A). Palps lost in all specimens. Peristomium short (Fig. 2A, B), partially enveloping prostomium and extending around the scar of the base of the palps forming low lateral wings (Fig. 2A, B) separated from chaetiger 1.
All notopodial postchaetal lamellae partially fused to branchiae with free and pointed tips (Fig. 2A–H, J), notopodial postchaetal lamellae on chaetigers 1–2 shifted dorsally and slightly serrated (Fig. 2A). Notopodial postchaetal lamellae on chaetiger 1 bearing 2–4/0–4 (holotype: 2/2 right, left side) digitiform papillae along the distal margin; basal margin entire (Fig. 2A). Notopodial postchaetal lamellae on chaetiger 2 with 0–2/0–1 (holotype: 1/2 right, left side) digitiform papillae along the distal margin (Fig. 2D), lamellae on chaetigers 3–7 (holotype: 3–11) slender, with ruffled distal and middle margins; basal margin wider, rounded (Fig. 2B, F–G); lamellae on subsequent chaetigers with entire margins (Fig. 2H) and lamellae on chaetigers 15–28 (holotype 27) and succeeding chaetigers with pointed ventral edges (Fig. 2H), gradually decreasing in size on posterior chaetigers. Ventral and dorsal edges of notopodial and neuropodial lamellae touching on chaetigers 41–45 (not touching in holotype and some paratypes) (Fig. 2H). Notopodial prechaetal lamellae on chaetiger 1 rounded, low; lamellae on chaetigers 2–4 large, rounded with enlarged dorsal edges (Fig. 2A, B), thereafter increasing in size, rounded, becoming wider on chaetigers 5–35, and subtriangular from chaetigers 36–41 (Fig. 2H), small and reduced in size posteriorly.
Each segment with a pair of dorsal J-shaped double bands of cilia (arranged obliquely) with a transverse band of cilia between them, present from the middle and posterior chaetigers (Fig. 2I), not observed in holotype. Lateral organs between notopodial and neuropodial postchaetal lamellae present from chaetiger 12 in some paratypes (not observed in holotype). The distribution of these organs is irregular.
All neuropodial postchaetal lamellae rounded and smooth on chaetigers 1–6 (Fig. 2B–E), shifted to dorsal side on chaetigers 1–2 (Fig. 2B), rectangular, wider on chaetiger 7 (Fig. 2F), becoming rectangular with a welldeveloped dorsal edge on chaetigers 26–33 (Fig. 2G), developing into a pointed upper edge from around chaetigers 28–40 (28 holotype) (Fig. 2H), subsequent parapodia decreasing in size with triangular upper and lower edges up to the end of the fragments. Neuropodial prechaetal lamellae small, rounded, wide (Fig. 2B, J); smaller on middle chaetigers, and decreasing gradually in size on posterior chaetigers; lamellae not fused with neuropodial postchaetal lamellae at the base.
Branchiae present from chaetiger 1 (Fig. 2A–C) continuing to end of fragments; all branchiae smooth, long, tapering, almost completely fused to notopodial lamellae (Fig. 2A); branchial tips free, distally lanceolate on all chaetigers (Fig. 2B–H), longer than notopodial lamellae (Fig. 2B–H). Each branchia with a dense band of cilia along its inner edge (Fig. 2C–H). Accessory branchiae present from chaetigers 18–23 (21 in holotype) on posterior side of notopodial base (Fig. 2G, H); initially as simple long digitate lobes, number of lobes gradually increasing to 8 on middle chaetigers and arranged in two rows.
Notochaetae on chaetiger 1 arranged in a dorsal tuft and a ventral fascicle: dorsal tuft with long, smooth, alimbate, slender capillaries extending beyond margins of notopodial lamellae; ventral fascicle arranged in two rows: both rows with long, smooth, alimbate, slender capillaries, anterior row shorter than posterior row. Notochaetae on chaetiger 2 also arranged in a dorsal tuft and a ventral fascicle: dorsal tuft with long, slender, smooth, alimbate capillaries; ventral fascicle with an anterior row of basally striated, reticulate, granulated, unilimbate capillaries and short tips (Fig. 2K), and a posterior row of smooth, alimbate capillaries with long pointed tips, striated basally (Fig. 2L). Notochaetae on subsequent chaetigers arranged as a dorsal tuft with long, slender, smooth, alimbate capillaries, and a ventral fascicle composed of two rows: both rows similar to anterior chaetigers, except that chaetae on the anterior row have wider limbation (Fig. 2M) than those on chaetiger 2, and those on the posterior row form granulated, long, alimbate capillaries (Fig. 2N). Chaetae on the middle and posterior notopodia arranged in a similar way to those on the anterior chaetigers, but with a dorsal tuft of striated, unilimbate capillaries (Fig. 2O), chaetae on the anterior row slightly striated, granulated, reticulated, unilimbate (Fig. 2P); those on the posterior row, slightly granulated, alimbate capillaries (Fig. 2Q). Notopodial hooded hooks absent.
Neurochaetae on chaetiger 1 arranged in 2 rows, anterior row composed of short reticulated, granulated, unilimbate capillaries (Fig. 2R), and posterior row of smooth, alimbate capillaries with pointed tips: chaetae longer than on anterior row; ventral tuft of five short, slender, smooth, alimbate capillary chaetae located in position of sabre chaetae; neurochaetae on chaetiger 2 the same as on chaetiger 1, except that capillaries on the posterior row slightly granulated, unilimbate, and with long pointed tips (Fig. 2S). Neurochaetae on chaetiger 3 and subsequent chaetigers the same as on chaetigers 1–2, but the chaetae on the ventral tuft are more granulated. Middle chaetigers with a row of unidentate neuropodial hooded hooks (Fig. 2T) from chaetigers 23 – 27 (24 in holotype), 5 – 8 hooks present per neuropodium with open hoods and subdistally slightly recurved shafts (Fig. 2T), each one accompanied by 2–3 very slender, short, smooth, alimbate capillary chaetae (Fig. 2U); posterior row with granulated, reticulated, unilimbate capillaries (Fig. 2V); plus a ventral tuft of granulated, reticulated, alimbate chaetae (Fig. 2W). In posterior chaetigers, chaetae on posterior row smooth and unilimbate (Fig. 2X); plus a ventral tuft of reticulated, granulated, unilimbate capillaries (Fig. 2Y) located in the position of the sabre chaetae.
Pygidium with two pairs of long dorsal cirri, and a ventral cushion (Fig. 2Z, Z’).
Remarks. Dispio elegans sp. nov. is similar to D. maroroi Gibbs, 1971 and D. longibranchiata Delgado-Blas & Díaz-Díaz, 2016 in that the first two notopodial postchaetal lamellae are serrated with digitiform papillae; the anterior neuropodial lamellae are smooth; all branchiae are almost completely fused to the notopodial lamellae, but with free tips; and the notochaetae on the posterior row of chaetiger 1 are smooth, alimbate capillaries. However D. elegans sp. nov. can be distinguished from D. maroroi and D. longibranchiata in that it has an oblanceolate prostomium, rather than a peanut shaped or rectangular prostomium. The branchiae in D. elegans sp. nov. are shorter and do not overlap or touch each other on anterior chaetigers, and the free tips are distally lanceolate on all chaetigers, while in D. maroroi and D. longibranchiata the branchiae are longer, and overlap or touch each other on the anterior and middle chaetigers (D. longibranchiata) or middle chaetigers (D. maroroi), and the tips are distally pointed in D. longibranchiata or distally pointed in a spear-shape in D. maroroi. The notochaetae on the anterior row of chaetiger 1 are smooth, alimbate capillaries (similar to D. longibranchiata), rather than heavily reticulated, unilimbated, pointed capillaries as in D. maroroi; the ventral chaetae located in the position of the sabre chaetae on chaetiger 2 are smooth, alimbate capillaries, rather than slightly to heavily reticular, granulated, unilimbated. In addition, Dispio elegans sp. nov. can be distinguished from D. longibranchiata in that the second pair of notopodial postchaetal lamellae are serrated with digitiform papillae, rather than entire and slightly ruffled on the distal and middle edges, and the anterior neuropodial lamellae are rounded, rather than subtriangular. Furthermore, D. elegans sp. nov. is similar to D. anauncinata Delgado-Blas & Díaz-Díaz, 2016 in that the first two notopodial postchaetal lamellae are serrated with digitiform papillae; the branchial structure and notochaetal structure of chaetiger 1 are similar; and the pygidium has two pairs of long anal cirri and a ventral cushion. However, D. elegans sp. nov. can be distinguished from D. anauncinata in that it has a oblanceolate, rather than a peanut shaped prostomium; the anterior neuropodial lamellae are smooth on chaetigers 1–2, rather than serrated with papillae; the branchiae are shorter and do not overlap or touch each other on anterior chaetigers; and the ventral chaetae located in the position of the sabre chaetae on chaetiger 2 are smooth, alimbate capillaries, rather than heavily reticulated, granulated and unilimbated. Further differences between this new species and the other species compared are provided in the Table 1.
The identity of the specimens recorded as D. uncinata from the coast of the Iberian Peninsula by Ibáñez & Viéitez (1973), Rodríguez et al. (1980), San Martín et al. (1982), Gómez & San Martín (1985), should be verified.
Methyl green staining pattern: no pattern.
……continued on the next page TABLE 1. (Continueđ) Etymology. The specific name is from the Latin elegans meaning elegant.
Type locality. Atlantic coast: Meira beach, Ría de Vigo, 41°17′N, 08°43′W, intertidal.
Habitat. Intertidal and sublittoral up to 15 m in depth. It is found in substrates of medium or fine sands with low mud (max. 1.43 %) and low organic matter (1–3.1 %) contents.
Geographical distribution. NE Atlantic, Cantabrian coast: Zarautz, Bay of Biscay; Covas beach, Esteiro beach, Lugo. Atlantic coast: Louro beach, A Coruña; Meira beach, Ría de Vigo.
description: Published as part of 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, pp. 525-538 in Zootaxa 4410 (3) on pages 529-534, DOI: 10.11646/zootaxa.4410.3.6, http://zenodo.org/record/1221840