Pilargis falconae, Ribeiro & Barbosa & Freitas & Zanol & Glasby & Ruta, 2020

Ribeiro, Rannyele Passos, Barbosa, Aline Da Cruz, Freitas, Roberta, Zanol, Joana, Glasby, Christopher J. & Ruta, Christine, 2020, Pilargidae (Annelida: Phyllodocida) from coastal and deep waters of the Southwestern Atlantic, with descriptions of two new species, Zootaxa 4878 (1), pp. 56-76 : 66-68

Pilargis falconae sp. nov.

Figures 7 A–C, 8A–D

urn:lsid:zoobank.org:act:D4F4E539-27F4-4D16-BBF6-574B031AC761

Material examined. BRAZIL: Campos Basin : Holotype: 21º50’2.96”S, 40º5’55.938”W, 476 m, one specimen, 7.ii.2009 (MNRJP-002731).

Comparative material examined. Pilargis verrucosa Saint-Joseph, 1899 : Northeastern Atlantic Ocean: syntypes, two specimens, females (MNHN-IA-TYPE1234-5); one specimen, male (MNHN-IA-TYPE1236).

Diagnosis. Body surface sparsely papillate. Dorsal tentacular cirri 1.5x longer than ventral ones. All dorsal cirri similar in length. Parapodial glands from first chaetiger on dorsal surface and from the sixth chaetiger on ventral surface. Neurochaetae smooth capillaries, limbate with limbus smooth, unidentate.

Description. Fixed specimen whitish with dark parapodial glands on dorsal and ventral surfaces ( Fig. 7 A–C; 8A, B). The following description is based on the holotype: size 20.89 mm long, 0.90 mm wide at widest point (including parapodia), 92 chaetigers. Body dorsoventrally flattened ( Fig. 7A , 8A ). Body surface with papillae minute and sparse, papillae abundant on cirrophores of tentacular and dorsal cirri, antennae and parapodial cirri ( Fig. 8D ). Prostomium with lateral antennae inserted on posterior margin; median antenna and eyes absent ( Fig. 7B , 8D ). Two biarticulated palps conical ( Fig. 7B , 8D ), palpophore large and palpostyle diminutive. Proboscis not observed. Peristomium dorsally distinct from prostomium with two pairs of tentacular cirri. Dorsal tentacular cirri 1.5x longer than ventral ones and 2.2x longer than lateral antennae. Parapodia sub-biramous and inflated; all parapodia have ventral and dorsal cirri in conical shape ( Fig. 8B ). Dorsal cirri of first chaetiger 1.2x longer than second one, and as long as following cirri ( Fig. 7B ); ventral cirri shorter than dorsal cirri. Cirrophores of dorsal cirri thick and globose, twice as long as cirrostyles. Parapodial glands darkly pigmented, some brownish to reddish, concentrated in elliptical clusters, present on dorsal surfaces of all parapodia, and on ventral surface from the chaetiger 6 and some absent between chaetigers 30 and 35 ( Fig. 7 A–C), ventral glands smaller than dorsal ones. Neuropodial lobes conical, smaller than dorsal cirri. Neurochaetae smooth capillaries variable in length, limbate with limbus smooth and unidentate tips; up to seven neurochaetae per fascicle ( Fig. 8C ). Posterior end abruptly tapering due to posterior regeneration, 12 regenerating segments; parapodial glands barely visible in regenerated segments ( Fig. 7C ). Pygidium with small papillae present on the posterior margin; anal cirri absent ( Fig. 7C ).

Distribution. Atlantic Ocean—Brazil, Campos Basin, specimen examined in this study.

Remarks. There is no doubt that the specimen examined belongs to the genus Pilargis , due to the absence of notochaetae. Among species with papillae small and sparsely distributed, P. falconae sp. resembles P. angeli Salazar-Vallejo & Harris, 2006 , P. berkeleyae Monro, 1933 , P. maculata Hartman, 1947 , and P. modesta Intes & Le Loeuff, 1975 (see Table 2 ). However, P. angeli is different in lacking parapodial glands either on the dorsal or ventral surface, and in having dorsal tentacular cirri 1.2x longer than ventral ones, while P. falconae sp. nov. has dorsal and ventral parapodial glands, and dorsal tentacular cirri 1.5x longer than ventral ones. Pilargis berkeleyae differs from P. falconae sp. nov. in having parapodial glands only in the most posterior segments and limbate chaetae bidendate, while P. falconae sp. nov. has parapodial glands from anterior chaetigers and limbate chaetae unidentate. Both P. maculata and P. modesta have dorsal parapodial glands from the first chaetiger. However, P. maculata differs from P. falconae sp. nov. in having bidentate capillaries, sub-spherical glands on the tentacular segment (peristomium), ventral glands from the first or second chaetigers, while P. falconae has limbate chaetae unidentate, lacks glands in the peristomium, and has ventral glands from the sixth chaetiger. On the other hand, P. modesta differs in having spherical-shaped glands located in the cirrophore, and cirrostyles one-fifth the length of cirrophores, while P. falconae sp. nov. has glands in elliptical clusters on the base of parapodia and cirrostyles half the length of cirrophores.

Etymology. Name is in honour of Ana Paula da Costa Falcão, marine biologist and member of the PETRO- BRAS technical staff who collaborated in the HABITATS Project.

Figures

FIGURE 7. Pilargis falconae sp. nov. A. Whole body. B. Anterior end. C. Posterior body showing regeneration. All images in dorsal view.Abbreviations. Dc: dorsal cirrus, La: lateral antenna, Pgl: parapodial gland, Pp: palp, Pt: prostomium, Py: pygidium, Reg: regeneration, Tdc: tentacular dorsal cirrus, Tvc: tentacular ventral cirrus. Scale bars: 2 mm (A), 200 µm (B, C).

FIGURE 8. Pilargis falconae sp. nov. A. Whole body, dorsal view. B. Parapodium from chaetiger 15, posterior view. C. Chaetae from midbody, dorsal view. D. Anterior body, dorsal view. Scale bars: 500 µm (A), 150 µm (B), 50 µm (C), 200 µm (D).