Namalycastis geayi (Gravier, 1901)

Ribeiro, Rannyele Passos, Alves, Paulo Ricardo, Almeida, Zafira da Silva de & Ruta, Christine, 2018, A new species of Paraonis and an annotated checklist of polychaetes from mangroves of the Brazilian Amazon Coast (Annelida, Paraonidae), ZooKeys 740, pp. 1-34 : 9-11

Namalycastis geayi (Gravier, 1901) Fig. 6

Type locality.

Ouanary, French Guiana (4°12'N, 51°39'W; estimated geolocation).

Material examined.

Caranguejos Island, 02°49'33.6"S, 44°28'51.1"W: one specimen, 17 December 2011 (NPM-Pol 082); one specimen, 27 March 2011 (NPM-Pol 882); one specimen, 20 October 2010 (NPM-Pol 884); all incomplete specimens.

Distribution.

Atlantic Ocean: French Guiana, Brazil (state of Maranhão).

Diagnosis.

Prostomium anterior end smooth or with a shallow cleft. Antennae extending short of the palpophore tip or of the prostomium tip. Two pairs of eyes nearly longitudinally arranged. Dorsal cirri short, similar in length throughout the body. Notochaetae present ( Glasby 1999).

Description.

Based on specimen NPM-Pol 884. Incomplete specimen with 4.93 mm long, 1.1 mm wide and 18 chaetigers. Body widest mid-anteriorly, tapering gradually anteriorly and posteriorly (Fig. 6A). Dorsum and venter convex. Epidermal pigment absent. Prostomium trapezoidal, some individuals with lateral indentation on prostomium (Fig. 6A). Prostomium anterior end smooth. Antennae short and smooth, extending short of the anterior end of the prostomium, laterally inserted. Two pairs of eyes, arranged nearly longitudinally on prostomium. Four pairs of tentacular cirri with indistinct cirrophores and smooth cirrostyles. Posterodorsal pair extending posteriorly to third chaetiger. Pharynx smooth, lacking paragnaths or papillae. Parapodia sesquirramous (sub-birramous). Dorsal cirri short, similar in length throughout the body. Neuropodial acicular ligulae bilobed. Notochaeta as sesquigomph spinigers present from third chaetiger. Neurochaetae as heterogomph spinigers in all fascicles. Supra-acicular sesquigomph spinigers (postacicular) shaft with boss 1.9 ×–2.0× length of collar (Fig. 6B). Shaft of heterogomph chaeta with boss slightly prolonged. Sub-acicular spinigers in anterior region of body with blades moderately serrated (Fig. 6C). Chaeta pale. Aciculae dark brown.

Colour.

Specimens in alcohol yellow. No pigment visible throughout the body.

Remarks.

First species record for Brazil. The collected specimens of this study were not complete, but they present the same characters of Namalycastis geayi (Gravier, 1901) based on the anterior end (Fig. 6A). The identification of this species is supported by the presence of only heterogomph spinigers in sub- and supra-preacicular fascicle in the parapodia (Fig. 6B, C). In the original description, N. geayi has been recorded in freshwater environments, muddy river banks, and in coarse sediments ( Gravier 1901). This study recorded N. geayi in mangroves and brackish water.