Paranaitis assimetrica, 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 : 129

Paranaitis assimetrica sp. nov.

Figs. 10–12

Holotype. Margin of continental shelf, Campos Basin , Brazil, Hab 13 Foz 32 R2, 21°55'51.2"S, 40°25'58.2"W, 49 m, 13 Mar. 2009 (ZUEC-POL-16341).

Paratypes. 5 paratypes, length ranging from 7–21 mm and number of segments ranging from 55–105. Paranaguá Bay , Paraná, Brazil: Itiberê River , 25°33’53.7”S, 48°21’19.7”W, intertidal, 20 Feb. 2010 (1 paratype, NHMD-207886); Mel Island, Pontal do Paraná, 25?33’13.3"S, 48?25’58.2"W, intertidal, Sep. 2011 (1 paratype, NHMD-207963). Margin of continental shelf, Campos Basin, Brazil: Hab 13 I01 R3 , 21°11'0.9"S, 40°28'27.1"W, 26 m, 5 Mar. 2009 (1 paratype, ZUEC-POL-16408); Hab 17 B02 R2 , 22°45'49.3"S, 41°45'33.5"W, 53 m, 16 Jul. 2009 (2 paratypes, ZUEC-POL-16500). In poorly sorted fine sand in estuarine areas and on the continental shelf.

Diagnosis. Dorsal cirri rounded, longer than wide. Rostrum of chaetal shaft with one long, conical, slender main fang, surrounded by small cylindrical teeth. Parapodial lobes strongly asymmetrical.

Description. Holotype a complete specimen with 61 segments, 10 mm long, 1.3 mm wide at median part of body, including parapodia and excluding chaetae. Body long, dorso-ventrally flattened, with uniform width, but slowly tapering at posterior end. Segments 1 and 2 dorsally fused, forming collar behind prostomium. Prostomium with ligule into a depression in posterior margin where rounded nuchal papilla lies ( Fig. 10A–B ). Paired frontal antennae and palps antero-laterally on prostomium, conical and robust, of unequal size, palps longer than antennae ( Fig. 10B ). One pair of epidermal eyes, brown and with lenses. Proboscis partially differentiated into proximal area, with five rows of conical and chitinous micropapillae (dorsal row wider than 4 latero-ventral rows), and distal area in which rough tubercles become more prominent ( Fig. 10C–D ). Terminal ring with 18 rounded papillae. Four pairs of anterior cylindrical tentacular cirri, biarticulate, with short cirrophores and long cirrostyles situated on first three segments. Cirri of segment 1 reaching segment 7. Dorsal and ventral cirri of segment 2 reaching segments 12 and 4, respectively. Dorsal cirri of segment 3 extending to segment 9. Segment 2 with neuropodial aciculae but lacking neuropodial lobes and chaetae ( Fig. 10E ). Neuropodia and ventral cirri from segment 3. Dorsal cirri with symmetrical and well-developed cirrophores without external extensions, from segment 4. Dorsal cirri on anterior segments rounded, discretely more elongated than those on median and posterior segments, longer than wide ( Fig. 10F–H ). Neuropodial lobes shorter than dorsal cirri and longer than ventral cirri, with clear acicula and bundles of chaetae. Prechaetal lobes bilobate, rounded and asymmetrical, supraacicular lobe considerably longer than subacicular lobe. Normal ventral cirri horizontally oriented in relation to lobes, asymmetrical, on anterior segments oval, on median segments rounded, and on posterior segments oval with truncated distal ends ( Fig. 10A ). Compound spinigerous chaetae from segment 3. Rostrum of chaetal shaft with one long, conical, slender main fang, surrounded by small cylindrical teeth; articles with serrated edges ( Fig. 11A–D ). Pygidium with one pair of cylindrical anal cirri with inflated bases and tapered distal ends ( Fig. 12A ). Median pygidial papilla present ( Fig. 12A–B ).

Coloration. Living individual with green coloration. Preserved specimens show yellowish pigmentation on the dorso-lateral areas.

Geographical Distribution. Atlantic Ocean, Brazilian continental margin; areas of the continental shelf in the Campos Basin ; Paranaguá Bay (Paraná, Brazil). Known from intertidal depths to 53 m.

Etymology. The species name is derived from the Greek word ἀσΥΜΜΕτρία, which means ‘to stretch’. The name stresses the fact that the supraacicular lobes are considerably longer than the subacicular ones.

Remarks. Paranaitis assimetrica sp. nov. differs from P. abyssalis , P. pumila , P. speciosa and P. uschakovi by the morphology of the dorsal cirri, which are rounded, longer than wide, and by the depth of the ligule, very similar to that of P. benthicola . The ligule and the rounded dorsal cirri are similar to those described for P. pumila , but these species differ in the position of the lateral antennae, presence of papillae on the proboscis, the sharp asymmetry of the parapodial lobes, and the shape of the anal cirri. Paranaitis assimetrica sp. nov. shares the presence of neuropodial acicula in the second segment with P. chitinosa sp. nov., P. caeca , P. misakiensis , P. polynoides , and P. pumila . It differs from P. benthicola and P. moritai because these species present neuroaciculae on the second segment. It differs from all other species by the supraacicular lobe considerably longer than subacicular lobe.

Figures

FIGURE 10. Paranaitis assimetrica sp. nov. A—Prostomium and tentaCular Cirri, dorsal view; B—Dorsal view of prostomium, showing nuChal papilla (blaCk arrow) in ligula; C—ProbosCis; D—Close-up of proximal part of probosCis; E— BlaCk arrow showing aCiCulum from segment 2; F—Parapodium from segment 12; B—Parapodium from segment 41; H— Parapodium from segment 80. SCales: A, 0.8 mm; B, 0.1 mm; C,0.12 mm; D, 0.05 mm; E, 0.2 mm; F, 0.1 mm; G, 0.05 mm; H, 0.05 mm.

FIGURE 11. Paranaitis assimetrica sp. nov. A–D—Compound spinigerous Chaetae of the holotype. SCales: A, 0.05 mm; B, 0.02 mm; C, 0.003 mm; D, 0.005 mm.

FIGURE 12. Paranaitis assimetrica sp. nov. A–B—Pygidium with one pair of anal Cirri and median papilla, ventral view. (A) Holotype. SCales: A, 0.05 mm; B, 0.1 mm.