Aonides selvagensis Brito, Núñez and Riera, 2006

Bick, Andreas, Guggolz, Theresa & Götting, Miriam, 2014, Spionidae (Polychaeta: Canalipalpata: Spionida) from seamounts in the NE Atlantic, Zootaxa 3786 (3), pp. 201-245 : 217-219

Aonides selvagensis Brito, Núñez and Riera, 2006

( Figure 6 )

Aonides sp. Núñez et al., 2001: 39.

Aonides selvagensis Brito, Núñez and Riera, 2006: 61 –63, figures 2–3.

Material examined. NE Atlantic Ocean, Expedition DIVA 3, cruise METEOR ME 79-1: Irving Seamount: 31°56.98'N 027°56.63'W, station 682, grab, depth 281.2 m, 21-Aug-2009, formalin, 1 af (ZMH-P27550); 31°56.98'N 027°56.66'W, station 683, grab, depth 281.1 m, 21-Aug-2009, 96% ethanol, 1 af (ZSRO-P2301); 31°56.98'N 027°56.67'W, station 684, grab, depth 280.8 m, 21-Aug-2009, formalin, 1 complete, 2 af (ZSRO- P2299); 31°56.98'N 027°56.71'W, station 687, grab, depth 280 m, 21-Aug-2009, formalin: 1 af ( SMF 23333), 1 af (ZMH-P27551); 31°56.96'N 027°56.51'W, station 679, grab, depth 282.5 m, 21-Aug-2009, 96% ethanol: 4 af ( SMF 23334), 1 af (ZSRO-P2300). Great Meteor Seamount: 30°00.04'N 028°30.05'W, station 660, grab, depth 287.2 m, 19-Aug-2009, formalin, 1 af ( SMF 23332); 30°00.04'N 028°30.05'W, station 664, grab, depth 287.9 m, 19-Aug-2009, formalin, 1 af (ZSRO-P2298).

Description. Small species, largest complete specimen 0.18 mm wide (at chaetiger 3) and 4.6 mm long for 49 chaetigers (SMF 23334); other specimens (mostly anterior fragments) with body widths between 0.10 and 0.14 mm. Prostomium conical, bluntly rounded anteriorly, posterior end of prostomium obtuse triangle, posteriorly not extended into a caruncle and clearly separated from following segments, without occipital antenna and eyes ( Figure 6 A–B). Nuchal organ not clearly detectable but metameric dorsal ciliated organs as pair of comma-shaped ciliary bands present from chaetiger 1 to last branchial chaetiger, additional anterior transverse ciliary band present on those chaetigers ( Figure 6 A–D). Branchiae cirriform, separate from notopodial lamellae, present from chaetiger 2–6 at maximum (i.e., maximally 5 pairs of branchiae present in our specimens) ( Figure 6 A, C–D). Postchaetal lamellae elongate with rounded tip or almost cirriform, particularly in middle and posterior chaetigers, in anterior chaetigers notopodial lamellae slightly longer and wider than neuropodial lamellae, in middle and posterior chaetigers about equal in size in both rami; praechaetal lamellae not observed in our material. Chaetae in branchial region all granulated bilimbate capillaries, thinner in diameter and less granulated towards postbranchial region; postbranchial region with thin smooth capillaries and tridentate hooded hooks in both rami, hooks with pair of apical teeth (side by side) above main fang ( Figure 6 E), hooks present from chaetiger 11 in neuropodia and from chaetiger 13 in notopodia, numbering 1–3 in neuropodia and 1–2 in notopodia. Pygidium with 5 cirriform anal cirri; two lateral pairs plus a single cirrus attached ventromedially, lateral cirri about equal in length, single cirrus either shorter or of equal length.

Pigmentation. Pigment absent in preserved specimens; colour white.

Methyl green staining pattern. Inconspicuous. Prostomium, parapodial lamellae, and branchiae most intensively stained.

Ecology. Aonides selvagensis was found on seamounts in coral and crushed shell gravel in about 250–300 m water depth during the DIVA 3 cruise. Other records come from marine caves with water depths up to 15 m and fine and muddy sands ( Brito et al. 2006).

Geographical distribution. Macaronesian Region (Great Meteor and Irving Seamounts, Savage Islands, Canary Islands).

Remarks. Our specimens from both the Great Meteor and Irving seamounts are identified as A. selvagensis based on the shape of the prostomium, the small number of branchiae (at maximum 5 pairs present from chaetiger 2), and the early start of neuropodial and notopodial tridentate hooded hooks on chaetigers 11 and 13, respectively. The species was originally described from the Savage Islands (Portuguese: Ilhas Selvagens), a small Macaronesian archipelago midway between Madeira and the Canary Islands, and has also been found near Tenerife, Canary Islands. Differences observed in comparison to the original description are as follows: our specimens possess 5 pairs of branchiae at maximum instead of 6–8 pairs; up to 3 and 2 hooks are present in the neuropodia and notopodia, respectively, in specimens from the Atlantic seamounts, whereas up to 5 and 4 hooks in the neuro- and notopodia, respectively, are reported by Brito et al. (2006). These deviations might be explained by the smaller size of our specimens (4.6 mm long and 0.18 mm wide in our material compared to 9.25 mm long and 0.23 mm wide in the orginal specimens). In the original description chaetae are described as all smooth capillaries. Based on our material, chaetae in the anteriormost chaetigers (up to chaetiger 5) were found to be bilimbate and granulated but smooth and without sheaths in following chaetigers. This observation was also confirmed by Jorge Nunez (pers. comm.) for specimens of A. selvagensis from the Savage Islands and thus this observation adds new details to the species description. The original description has also been enhanced by providing information on nuchal and metameric dorsal ciliated organs of this species.

Figures

FIGURE 6. Aonides selvagensis Brito, Nunez and Riera, 2006: A. Anterior end, dorsal view. B. First chaetiger with transverse ciliary band (tcb) and comma-shaped dorsal ciliated organs (dco), dorsal view. C. Third chaetiger with comma-shaped dco, tcb not clearly detectable, dorsal view. D. Fith chaetiger with tcb and dco, dorsal view. E. Hooded hook with pair of apical teeth above main fang from notopodium of a posterior chaetiger; arrows point at the two apical teeth. — All from Great Meteor Seamount (SMF 23332), Scale: A 50 µm, B – D 10 µm, E 1 µm.