Semiodera mezianei, Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 29-31

Semiodera mezianei n. sp.

Figure 10

Pherusa parmata: Rullier & Amoureux 1979:182 (non Grube, 1878).

Type material. Southwestern Atlantic Ocean. Argentina. Holotype ( MNHN-1550 ), and paratype ( MNHN-889 ) complete, body wall slightly broken, apparently by compression, RV Calypso 1961 Expedition, Stat. 181, Golfo Nuevo, Punta Cracker, 18 m, 2 Jan. 1962 (paratype 17 mm long, 1.8 mm wide, cephalic cage 7 mm long, 58 chaetigers). Brazil. One paratype ( MNHN-889 a), mature female, partially dried-out, with a midventral, anterior dissection, dorsal shield lost, RV Calypso 1961 Expedition, Stat. 94 (20°53' N, 40°41' W), off Vila Velha, 13 m, 30 Nov. 1961 (14 mm long, 1.5 mm wide, cephalic cage broken, 4 mm long, 69 chaetigers).

Additional materials: Southwestern Atlantic Ocean. Brazil. Two specimens ( MNHN-889 b), anterior fragment and the other without posterior end, breaking in two pieces by dissection, dorsal shields removed, body wall eroded, RV Calypso 1961 Expedition, Stat. 129 (23°40' S, 45°01' W), E off Caraguatatuba, 37 m, 10 Dec. 1961. Five specimens ( MNHN-889 c), separated in two lots, anterior fragment and four complete including two mature females, body wall variously broken, RV Calypso 1961 Expedition, Stat. 136 (24°06' S, 45°29' W), off Ilha de São Sebastião , 48 m, 11 Dec. 1961 (13.5–20.0 mm long, 1.5–2.0 mm wide, cephalic cage 6–7 mm long, 51–70 chaetigers; oocytes 100 µm, pale dark with darker nuclei) .

Description. Holotype (MNHN-1550) complete, slightly contracted, body wall broken medially, some parapodia removed ( Fig. 10A); paratype contracted, without pygidium. Body swollen anteriorly, tapering posteriorly; 15.5 mm long, 2 mm wide, cephalic cage 7 mm long, 60 chaetigers. Tunic thin, areolated, almost without sediment particles; body papillae large, arranged in single rows ( Fig. 10B, C), additional papillae appear by median chaetigers; dorsal papillae larger, bottle-shaped, ventral papillae smaller, bottle-shaped or digitate.

Anterior end not exposed. Not dissected to avoid further damage. Cephalic cage chaetae 3.5 times longer than body width. Chaetigers 1–2 forming cephalic cage; chaetae arranged in transverse rows in chaetiger 1, become more lateral in chaetiger 2. Chaetiger 1 with 10 noto- and 12 neurochaetae; chaetiger 2 with 6 noto- and 8 neurochaetae per bundle.

Anterior dorsal margin of first chaetiger with a projected, trifid dorsal lappet, each lobe with a distal papilla. Three other papillae by notochaetal insertion, other papillae not seen, probably eroded. Chaetigers 1–2 of about the same size, chaetiger 3 slightly longer. Sand cemented anterior shield dorsal, over chaetigers 1–4, slightly expanded over chaetiger 5 (in other paratypes, posteriorly elevated, with some anterior tapering papillae, Fig. 10C). Chaetal transition from cephalic cage to body chaetae gradual; neurochaetae multiarticulate capillaries in chaetigers 1–2, pseudocompound hooks from chaetiger 3, decreasing in size progressively. Slightly falcate, anchylosed neurohooks from chaetiger 7. Gonopodial slits not seen.

Parapodia better developed in chaetigers 1–3; thereafter low chaetal lobes, with two long bottle-shaped interramal papillae per parapodia. Notochaetal lobes with three postchaetal papillae. Neuropodial lobes with three postchaetal papillae. Large papillae in single transverse series in anterior and median chaetigers, anterior chaetigers with most papillae large, median chaetigers with alternating sizes. Posterior segments with fewer papillae, more or less forming transverse series. Noto- and neuropodia lateral, close to each other.

Median notochaetae arranged in short transverse rows; all multiarticulate capillaries, articles very long ( Fig. 10E, F). Neurochaetae multiarticulate capillaries in chaetigers 1–2, pseudocompound hooks in chaetigers 3–6 ( Fig. 10D), progressively decreasing in size, anchylosed falcate hooks from chaetiger 7. First 2–3 per bundle, up to 6 in chaetigers 9–18 ( Fig. 10E), decreasing to 4 by chaetigers 19–28, then three per bundle up to chaetiger 40 ( Fig. 10F), thereafter two per bundle, decreasing to one in far posterior chaetigers.

Posterior region tapering to a blunt cone, pygidium conical, anus terminal; no anal cirri.

Etymology. The species name is a modest homage to Dr. Tarik Meziane, curator of the polychaete collection in the Museum National d’Histoire Naturelle, Paris. While he is really an ecophysiologist rather than a taxonomist, he has found the means to support taxonomical studies of many people, including myself.

Type locality. Punta Cracker , Golfo Nuevo, Argentina, 18 m depth .

Variation: The specimens were 14–20 mm long, 1.5–2.0 mm wide, cephalic cage 6–7 mm long, and 51–70 chaetigers.

Remarks. Semiodera mezianei n. sp., is very similar to S. inflata ; but differs by having papillae of almost the same size, larger than in S. inflata , and the papillae present under chaetal lobes are much larger too.

There is another species described from Brazil. Grube (1877:67, 71) included Stylarioides cingulatum Grube & Krøyer in Grube, 1877. The species was diagnosed as having “Papillen auf Segment 3–11 einen Gürtel, auf den andern Segmenten blos eine Querreihe auf dem Rücken bildend“ (translation: Dorsal papillae on chaetigers 3–11 arranged in a belt, on the other segments only as a transverse row). The type material was not found in Copenhagen, Berlin or Wroclaw, and is presumed lost. The species is herein regarded as indeterminable.

Distribution. There are some records for the Brazilian materials including from the Rocas island to Golfo Nuevo, Argentina, but there might be more than one species involved. The other specimens were collected in Southeastern Brazil, in mixed bottoms, 13–48 m depth.