Paranaitis cirriformata, Oliveira & Jacobsen & Lana, 2018

Oliveira, Verônica Maria De, Jacobsen, Danny Eibye & Lana, Paulo, 2018, Four new species of Paranaitis Southern, 1914 (Phyllodocidae, Annelida) from southern and southeastern Brazil, Zootaxa 4444 (2), pp. 120-136 : 127

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Paranaitis cirriformata

sp. nov.

Paranaitis cirriformata sp. nov.

Figs 8–9 View FIGURE 8 View FIGURE 9

Holotype. Margin of continental shelf, Campos Basin , Brazil, Hab 17 Foz 15 R01, 21°10'17.4"S, 40°45'57.0"W, 20 m, 22 Jul. 2009 (ZUEC-POL-16339). GoogleMaps

Paratypes. 2 paratypes, length ranging from 4–11 mm for 36–104 segments. Paranaguá Bay , Paraná, Brazil: In front of Port Paranaguá , 25°30'41.6"S, 48°29'50.3"W, intertidal, Aug. 2011 (1 paratype, NHMD-207863). Continental shelf of Campos Basin : Hab 17 Foz 15 R1 GoogleMaps , 21°10'17.4"S, 40°45'57.0"W, 20 m, 22 Jul. 2009 (1 paratype, ZUEC-POL-16340). Collected in silt-clay, poorly sorted bottoms on the slope and in coarse sand, sorted bottoms on the continental shelf from the intertidal down to a depth of 52 m.

Diagnosis. Presence of a pair of cavities or fissures between prostomium and peristomium. Proximal part of proboscis with lateral papillae and dorsal chitinous papillae; 4 longitudinal rows of tubercles, 2 pairs on each side, gradually forming rows of tubercles, terminal part with proboscideal ring with oval papillae. One pair of long, cirriform pygidial cirri.

Description. Holotype complete specimen, 10 mm long for 61 segments, 1.4 mm wide at median part of body, including parapodia and excluding chaetae. Body long, dorso-ventrally flattened, of uniform width, tapering at posterior end. Prostomium anteriorly rounded, wider than long, with ligule creating distinct depression in posterior part, where nuchal papilla inseres, resembling a rounded button ( Fig. 8A–B View FIGURE 8 ). Nuchal organs present on each side of prostomium ( Fig. 8B View FIGURE 8 ). Paired frontal, conical and robust antennae and palps, of equal size, postero-laterally positioned on prostomium. Antennae and palps 1/4 as long as prostomium ( Fig. 8A–B View FIGURE 8 ). A pair of brown eyes, subepidermal, with lenses, located at posterior margin of prostomium. Proximal part of proboscis with lateral papillae and dorsal chitinous papillae; four longitudinal rows of tubercles, two pairs of rows on each side, terminal part of proboscideal ring with oval papillae ( Fig. 8C View FIGURE 8 ). Terminal ring of proboscis with oval papillae. First and second segments dorso-ventrally fused as a collar, laterally with pair of cavities at border of prostomium ( Fig. 8B View FIGURE 8 ). Four pairs of cylindrical tentacular cirri, biarticulate, with short cirrophores and long cirrostyles, arranged on first three segments. Cirri of segment 1 reaching segment 6. Dorsal and ventral cirri of segment 2 reaching segments 13 and 5, respectively. Dorsal cirri of segment 3 extending to segment 10. Aciculae not observed in segment 2. Neuropodia and ventral cirri from segment 3. Dorsal cirri symmetrical, with asymmetrical, well-developed cirrophores without external extension, rounded, from segment 4. Dorsal cirri longer than wide in anterior segments, clearly wider than long in median segments, and almost as wide as long in posterior segments. Parapodial lobes shorter than dorsal cirri and longer than ventral cirri, with aciculae and neurochaetae. Prechaetal lobes bilobate, asymmetrical and rounded, supraacicular lobe twice as wide as subacicular lobe. Ventral cirri horizontally oriented in relation to parapodial lobes, asymmetrical, on anterior segments oval with rounded edges, on median and posterior segments longer ( Fig. 8D–F View FIGURE 8 ). Compound spinigerous chaetae from segment 3. Rostrum of chaetal shaft asymmetrical, with large, conical main fang, base of fang surrounded by small cylindrical teeth of unequal length; chaetal articles with serrated outer edges ( Fig. 9A–C View FIGURE 9 ). Pygidium with two pairs of cylindrical anal cirri, cirriform and slender. Cylindrical pygidial papilla present ( Fig. 9D View FIGURE 9 ).

Coloration. Preserved specimens are opaque.

Distribution. Atlantic Ocean, Brazilian continental margin; areas of the continental shelf in the Campos Basin. Itiberê River in Paranaguá Bay, Paraná—Brazil.

Etymology. The name of this species is derived from the Latin word cirrus (cirrus) and formis (shape) and refers to the morphology of the anal cirri.

Remarks. The small number of specimens, almost all fragmented, hindered the careful observation of the pygidial region. We observed two pairs of pygidial cirri in the holotype (ZUEC-POL-16339), but we do not rule out the possibility that this is a morphological anomaly. Paranaitis cordiformata sp. nov. differs from P. abyssalis ( Hartmann-Schröder, 1975) , P. benthicola , P. bowersi , P. caeca , and P. uschakovi in having eyes, but also in the morphology of the dorsal cirri, which are almost circular in P. abyssalis and P. benthicola , and reniform in P. caeca , P. bowersi and P. usachakovi . Paranaitis cirriformata sp. nov. shares the rounded median dorsal cirri, wider than long, with P. speciosa , but they differ in the presence of a rounded proboscideal papillae in, asymmetrical dorsal cirrophores and cylindrical anal cirri in the first. P. cirriformata sp. nov. iffers from the other species of Paranaitis by the presence of nuchal organ on each side of the prostomium ( Kato & Pleijel, 2003) and cylindrical and long anal cirri. The anal cirri of P. kosteriensis are also cylindrical but much shorter than in P. cirriformata sp. nov.