Phyllodoce lamella, Oliveira & Magalhães & Lana, 2021

Oliveira, Verônica Maria De, Magalhães, Wagner F. & Lana, Paulo Da Cunha, 2021, Ten new species of Phyllodoce Lamarck, 1818 (Phyllodocidae, Annelida) from Brazil, Zootaxa 4924 (1), pp. 1-61 : 24-26

Phyllodoce lamella sp. nov.

urn:lsid:zoobank.org:act:879866AA-9E0C-4118-B91F-A9BD32B5B294

Figures 18–19

Holotype. Margin of continental shelf in Campos Basin, Brazil, Hab 13 I04 R2 , 21°9’10.1”S 40°16’7.2”W, 101 m, 7 Mar 2009 ( ZUEC–POL 16585 )

Paratypes. A total of 6 paratypes, length 7.6 ± 5.9 mm for 46.6 ± 37.1 segments. Continental shelf in the Campos Basin : Hab 8 F10 R1 , 22º28’16.0”S 39º50’33.0”W, 1935 m, 25 Feb 2009 (1 paratype, NHDM–865960); Hab 11 G04 R2 , 22º4’14.3”S 40º6’59.4”W, 91 m, 25 Feb 2009 (1 paratype, NHDM–865962); Hab 13 I04 R3 , 21º9’9.3”S 40º16’5.3”W, 110 m, 7 Mar 2009 (1 paratype, NHDM–865961); Hab 13 D03 R1 , 22º19’32.0”S 40º37’18.9”W, 75 m, 15 Mar 2009 (1 paratype, ZUEC–POL 16388 ); Hab 13 H03 R1 , 21º43’10.3”S 40º11’30.7”W, 73 m, 9 May 2009 (1 paratype, ZUEC–POL 16389 ); Hab 16 E04 R2 , 22º17’42.1”S 40º27’0.0”W, 103 m, 4 Jul 2009 (1 paratype, ZUEC–POL 16462 ), Brazil .

Diagnosis. Proximal part of proboscis with two rows of dorsal papillae, each row with six papillae; 12 longitudinal rows of dorsal and lateral papillae, six rows on each side. Ventral cirri cylindrical with lateral lamellae. Reddish to brownish pigmented spots (probably chromatophores) on parapodial bases throughout.

Description. Holotype ovigerous female, incomplete, 2.2 mm long, 0.25 mm wide at median part of body, including parapodia and excluding chaetae for 23 segments. Body long, dorso-ventrally flattened and slightly tapering posteriorly. Prostomium cordiform to pentagonally shaped, longer than wide with narrow anterior part where antennae and palps situated ( Fig. 18A ). Nuchal papilla present, rod-like. Paired frontal antennae and palps cylindrical, slender and of similar lengths; palps more robust than antennae. Antennae and palps of half prostomial length. Eyes absent. Reddish to brownish chromatophores present on prostomium and dorsal and ventral parapodia ( Fig. 18A ). Proboscis basally with 12 longitudinal rows, six on each side, each with 1–6; 2–7; 3–8; 4–9; 5–10; 6–9 rounded papillae, separated by latero-dorsal and median-ventral non-papillated areas; two median-dorsal rows separated by non-papillated areas. Distal region with longitudinal rows of tubercles. Terminal ring not observed ( Fig. 18B ). Segment 1 not visible dorsally. Four pairs of cylindrical tentacular cirri on first three segments, biarticulated, with short cirrophores and long cirrostyles, except for cylindrical ventral cirrus with lateral lamella ( Fig. 18 B–D). Dorsal tentacular cirri of segment 1, reaching segment 6. Dorsal and ventral tentacular cirri of segment 2 reaching segments 5 and 7, respectively. Dorsal tentacular cirri of segment 3 extending to segment 10. Neuropodia with chaetae from segment 2 ( Fig. 19B ). Dorsal cirri from segment 4 with well-developed cirrophores with dorsal expansion on median and posterior parapodia. Dorsal cirri symmetrical and oval; cirri from median segments longer than anterior ones; posterior cirri more rounded than median ones. Parapodial lobes shorter than dorsal and ventral cirri with light-brown aciculae and bundles of chaetae. Prechaetal lobes bilobate, symmetrical and rounded. Postchaetal lobes rounded. Ventral cirri from segment 3, horizontally oriented in relation to lobes, asymmetrical and dorso-ventrally flattened; cirri rounded with tapered distal ends anteriorly, elongated and slender on median and posterior segments ( Fig. 19 A–D). Compound spinigerous chaetae uniform from segment 2. Rostrum of chaetal shaft surrounded by conical denticles; articles with serrated outer edges. Pygidium not observed.

Colour. Preserved specimens show dark brown pigmentation in the prostomium and parapodial cirri ( Fig. 18A ). Dorsal and ventral pigmented patches interpreted as chromatophores at parapodial base and present throughout the body ( Fig. 18A ).

Habitat. Continental shelf and slope with a predominance of silty sediments between 71 and 1.935 m depths.

Distribution. Atlantic Ocean, Brazil: Margin of continental shelf and slope in the Campos Basin.

Etymology. The name of this species is derived from the Latin word lamella referring to the presence of lateral expansions in the ventral tentacular cirri.

Remarks. Phyllodoce lamella sp. nov. differs from other similar species by having cylindrical ventral tentacular cirri with lateral lamella, a character reported for species of Eulalia . The dorsal expansions of the cirrophores from the dorsal cirri are robust and remain attached to their bases even when cirri are lost. Phyllodoce lamella sp. nov. differs from P. concava sp. nov. in the morphology of the ventral tentacular cirri, which in this species, they are cylindrical with lateral lamellae and cylindrical but lacking such lamellae in P. concava sp. nov. This new species differs from P. micrognatha sp. nov. by the presence of subrectangular median-dorsal cirri with rounded edges, and from P. ovalis sp. nov. that has rounded to oval dorsal cirri. In addition, it differs from P. tamoya sp. nov., P. tupana sp. nov., and P. bipapillosa sp. nov. by the presence in these species of cordiform anterior dorsal cirri.

The presence of pigmented spots associated with the parapodia and present throughout the body has been interpreted as lateral chromatophores, a common feature of holopelagic clades of Phyllodocida that may have survival value given their disruptive for any other benthic phyllodocid taxa. It may represent a retained larval feature, which needs further investigation.

Figures

FIGURE 18. Phyllodoce lamella sp. nov. A, anterior region, dorsal view; B, everted proboscis of the holotype, dorsal view; B–C, ventral cirri with lateral lamellae; D, cirrophores with dorsal extensions shown by black arrow. Abbreviations: Ch, chromatophores (black arow); deCir, dorsal extension of the cirrophore. Scale bars: A–B, 0.2 mm; C–D, 0.7 mm.

FIGURE 19. Phyllodoce lamella sp. nov. Anterior view of the parapodia of the holotype.A, parapodium 6; B, parapodium 64; C, parapodium 117; D, Parapodium 6; E, parapodium 64; F, parapodium 117. Scale bars: A, C, D, F, 0.03 mm; B, E, 0.05 mm. Scale bars: A–C, 0.03 mm; B, E, 0.05 mm.