Paranaitis cordiformata, 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 : 132-135

Paranaitis cordiformata sp. nov.

Figs 13–14

Holotype. Margin of continental shelf, Campos Basin, Brazil, Hab 17 I03 R01, 21°23'38.0"S, 40°15'37.1"W, 88 m, well-sorted fine sediment, 21 Jul. 2009 (ZUEC- POL-16342).

Paratype. A total of 7 paratypes, length ranging from 5–20 mm and number of segments ranging from 25– 115. Paranaguá Bay , Paraná, Brazil: Cotinga Channel, 25°30'41.6"S, 48°29'50.3"W, intertidal, 1 Feb. 2011 (1 paratype, NHMD-207973); Maciel shoal, 25°33'23"S, 48°24'58"W, 13 Apr. 2010 (1 paratype, ZUEC-POL-16489); Papagaios shoal, 25°32'56"S, 48°26'08"W, Jun. 2011 (1 paratype, ZUEC-POL-16564) . Paranaguá Bay , 25°30'41.6"S, 48°29'50.3"W, Sep. 2011, intertidal (2 paratypes, NHMD-207984) ; Itiberê River , 25°30'41.6"S, 48°29'50.3"W, Aug. 2011 (1 paraatype ZUEC-POL-16570). Margin of continental shelf, Campos Basin, Brazil: Hab 11 D2 R03, 22°12'53.4"S, 40°51'12.4"W, 52 m, 26 Feb. 2009 (1 paratype, ZUEC-POL-16367). Occurs in wellsorted fine sediment up to 52 m.

Diagnosis. Dorsal cirri cordiform and asymmetrical. Chaetae with main tooth conical and short, from segment 2. Pair of cylindrical anal cirri with wide base and tapered distal ends. Rostrum of chaetal shaft with large, conical main fang surrounded by cylindrical denticles of unequal lengths.

Description. Holotype complete with 97 segments, 15 mm long, 1.0 mm wide at the median part of body, including parapodia and excluding chaetae. Body long, dorso-ventrally flattened, with uniform width, except for small tapering region at posterior end. Prostomium triangular, wider than long, anteriorly rounded, with one short nuchal papilla ligule in a distinct depression, in its posterior portion, where rounded nuchal papilla lies ( Fig. 13A– B ). Paired frontal antennae and palps antero-laterally on prostomium, conical and robust, antennae and palps of equal size, long with tapered distal ends. One pair of subepidermal brown eyes with lenses. Proboscis not everted, not observed. First and second segments dorsally fused to form a collar. Four pairs of cylindrical tentacular cirri, biarticulate, with short cirrophores and long and cylindrical cirrostyles, gradually tapered at distal end, situated on first three segments. Cirri of segment 1 reaching segment 4. Dorsal and ventral cirri of segment 2 reaching segments 5 and 4, respectively. Dorsal cirri of segment 3 reaching segment 11 ( Fig. 13A–B ). Aciculae not observed in segment 2. Neuropodia and ventral cirri from segment 3. Dorsal cirri with symmetrical cirrophores, developed, without dorsal extension, from segment 4, cordiform and symmetrical. Dorsal cirri on anterior segments distally tapered, on medium segments with more rounded tips, and on posterior segments almost as long as wide ( Fig. 13D–E ). Parapodial lobes shorter than dorsal and ventral cirri, with clear aciculae and bundles of chaetae. Prechaetal lobes bilobate, asymmetrical and rounded, supraacicular lobes clearly wide than subacicular lobes. Ventral cirri horizontally oriented in relation to lobes, asymmetrical, on anterior segments oval and distally rounded, on medium segments oval and distally rounded, but with weak tip pointing downwards, and on posterior segments oval, more slender and more symmetrical ( Fig. 13A–C ). Compound spinigerous chaetae from segment 2 ( Fig. 13C ). Rostrum of chaetal shaft with large, conical main fang surrounded by cylindrical denticles of unequal lengths, articles with serrated outer edges ( Fig. 14A–C ). Pygidium with one pair of cylindrical anal cirri with wide base and tapered distal ends. Median pygidial papilla absent ( Fig. 14D ).

Coloration. Preserved specimens are opaque.

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

Etymology. The species name comes from the Latin word cordis and refers to the shape of the dorsal cirri.

Remarks. The cordate shape of the dorsal cirri in Paranaitis cordiformata sp. nov. is similar to those in P. wahlbergi and P. gardineri ; on the other hand, they are completely different from the rounded and reniform dorsal cirri described in P. bowersi , P. caeca , P. gardineri , P. moritai , P. uschakovi and P. wahlbergi . This species is similar to P. speciosa by the presence of nuchal papilla and primary chaetal teeth ( Kato & Pleijel, 2003); however, it differs in the shape of dorsal and anal cirri, which are more rounded in P. speciosa . Paranaitis cordiformata sp. nov. shares the anal cirri morphology with P. gardineri but it differs by the absence of a median pygidial papilla and the cylindrical shape of the anal cirri. Paranaitis cordiformata sp. nov. differs from P. cirriformata sp. nov., P. assimetrica sp. nov., P. bowersi , P. caeca , P. inflata , P. gardineri , P. kosteriensis , P. misakiensis , P. polynoides , P. pumila , P. speciosa , and P. uschakovi in lacking a pygidial papilla. The cylindrical anal cirri with inflated bases are shared with P. caeca , P. gardineri , and P. polynoides . Paranaitis cordiformata sp. nov. shares the presence of neuropodial chaetae in the second segment with P. benthicola and P. moritai . However, it differs from P. chitinosa sp. nov., P. assimetrica sp. nov., P. caeca , P. misakiensis , P. polynoides , and P. pumila , in which neuropodial aciculae are present in the segment 2.

Figures

FIGURE 13. Paranaitis cordiformata sp. nov. A–B—Prostomium and tentaCular Cirri, dorsal view. A–B—Holotype; C— Parapodium of the seCond segment with Chaetae; D—Parapodium from segment 9. E—Parapodium from segment 30. F— Parapodium from segment 60. SCale bars: A, 1.0 mm; B, 0.6 mm, C 0.2 mm, D, 0.08, E, 0.05 mm; F, 0.07 mm.

FIGURE 14. Paranaitis cordiformata sp. nov. A–C—SubaCiCular Chaetae from anterior parapodia (note variation in the two ConiCal teeth at the distal end of the rostrum of the Chaetal shaft); D—Pygidium with anal Cirri. A–D—Holotype. SCale bars: A, 0.01 mm; B, 0.012 mm; C, 0.004 mm; D, 0.05 mm; ACirs = Anal Cirrus sCar.