Webbnesia maculata, Núñez & Barnich & Monterroso, 2022

Núñez, Jorge, Barnich, Ruth & Monterroso, Óscar, 2022, A new genus and species of Polynoidae (Annelida: Polychaeta) from the Canary Islands, and update on taxa present in the Northeast Atlantic, European Journal of Taxonomy 846 (1), pp. 55-74 : 63-69

Webbnesia maculata gen. et sp. nov.

urn:lsid:zoobank.org:act:3128B356-28DC-4072-BC95-7DC8454AC1D3

Figs 2–6 , Tables 2–3

Diagnosis

PROSTOMIUM. Without cephalic peaks. Lateral antennae inserted ventrally. Two pairs of eyes, anterior pair dorsolateral, posterior pair dorsal.

ELYTRA. With smooth margins, surface with scattered, conical microtubercles and pigmented patches.

ANTENNAE AND CIRRI. Tapering, papillate.

PARAPODIA. With reduced notopodium and prominent neuropodium; neuropodium with minute (i.e., reduced) supra-acicular process, aciculum penetrating subdistally.

CHAETAE. Notochaetae stout with faint rows of spines and entire tip. Neurochaetae stout with distinct rows of spines and falcate, entire tip.

Etymology

The species epithet refers to the characteristic pigmented patches on the elytra, described by the Latin word ‘ maculatus ’ in its female form.

Material examined

Holotype CANARY ISLANDS • ovigerous ♀ (complete, with 33 segments); NE Atlantic , east coast of Gran Canaria, off Tufía; 27°57.91′ N, 15°22.63′ W; 27 m depth; Feb. 2019; fine sands; TFMCBM-AN/246 .

Paratypes CANARY ISLANDS • 1 spec. (anterior fragment of 11 segments); NE Atlantic , south coast of Gran Canaria, off Castillo del Romeral; 27°47.79′ N, 15°24.40′ W; 39 m depth; Oct. 2020; coarse sands; TFMCBM-AN/247 • 1 spec. (posterior fragment of 12 segments); NE Atlantic , south coast of Gran Canaria, off Castillo del Romeral; 27°47.73′ N, 15°23.49′ W; 60 m depth; Oct. 2020; coarse sands; TFMCBM-AN/248 • 1 spec. (anterior fragment of 16 segments); NE Atlantic , south coast of Tenerife, off Granadilla; 28°3.56′ N, 16°30.20′ W; 22 m depth; 18 Sep. 2013; coarse sands; SMF 32262 .

Description of holotype

MEASUREMENTS. Holotype, complete specimen of 8 mm length and 2 mm width in anterior body region.

BODY. Flattened dorsoventrally, short, with 33 segments, dorsum covered by elytra ( Fig. 3A ); ovigerous female ( Fig. 4C–D ).

PROSTOMIUM. Cephalic peaks absent, lobes anteriorly rounded. Median antenna with ceratophore in anterior notch, style tapering, papillate; lateral antennae with ceratophores inserted ventrally, styles tapering, papillate. Anterior pair of eyes dorsolateral in front of widest part of prostomium, posterior pair dorsal near posterior margin ( Figs 2A , 3B ).

TENTACULOPHORES. Inserted laterally to prostomium, with a pair of dorsal and ventral tentacular cirri; styles tapering, papillate ( Figs 2A , 3B ).

ELYTRA. Fifteen pairs on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 26, 29 and 32. Elytral margins smooth; surface with scattered, conical microtubercles and five pigmented patches ( Figs 2B , 3A–B , 4A–B ).

CIRRI. Dorsal cirri from segment3 on segments without elytra; cirrophore inserted dorsally on notopodium; style tapering, papillate ( Figs 2A, C , 3A–D , 4D ). Ventral cirri from segment 2 on all segments; first pair distinctly larger than following; style tapering, papillate ( Figs 2C , 3D ). Pair of pygidial cirri similar to dorsal cirri.

DORSAL TUBERCLES. Conical, one pair present on all cirrigerous segments, situated on dorsum in line with elytrophores of adjacent segments ( Fig. 2A, C ).

PARAPODIA. Notopodium reduced, with notoaciculum penetrating distally (may be withdrawn). Neuropodium more prominent, with elongate, conical prechaetal lobe and shorter, rounded postchaetal lobe; prechaetal lobe acicular with minute (i.e., reduced) supra-acicular process and neuroaciculum penetrating subdistally ( Figs 2C–D , 4D , 5 ).

CHAETAE. Notochaetae few (2–3), stout, with faint rows of spines and blunt, entire tip ( Figs 2C–E , 6A ). Neurochaetae more numerous (up to 18), stout, with falcate, entire (i.e., unidentate) tip; upper neurochaetae distally rather straight and spinose region elongate with pronounced rows of spines; middle and lower neurochaetae distally more curved and spinose region shorter with less marked rows of spines ( Figs 2C–D, F , 4D , 6B–D ).

Pigmentation (animals preserved) ( Figs 2A–B , 3A–D , 4A )

Body dorsally mostly white with brown patches; ventrally with 13 intersegmental, incomplete transverse bands in posterior body region. Prostomial lobes with diffuse pigmentation; basal part of median antenna and all of lateral antennae darkly pigmented. Tentacular cirri unpigmented. Dorsal and ventral cirri pigmented basally throughout body, also pygidial cirri similarly pigmented. Elytra usually with five pigmented patches: one circular above place of attachement to elytrophore, the others irregularlyshaped, two on the inner lateral part and two on the posterior part.

Distribution and habitat

NE Atlantic, Canary Islands: E and S of Gran Canaria and S of Tenerife; in 22 to 60 m depth.

The substrate at the Tufía station is characterised by areas of fine sand and poorly consolidated maerl. The faunal composition is dominated by the polychaetes Paradoneis armata Glémarec, 1966 and Aponuphis ornata (Fauvel, 1928) and the crustaceans Apseudopsis rogi Esquete, 2016 and Urothoe marina (Spence Bate, 1857) .

At the Castillo del Romeral stations the substrate is characterised by gravel and coarse organogenic sand. The dominant polychaetes are Pisione guanche San Martín, López &Núñez, 1999 and Syllis gerundensis (Alós & Campoy, 1981) ; the most abundant species are the bivalve Gouldia minima (Montagu, 1803) and the amphipod Photis longicaudata (Spence Bate & Westwood, 1862) .

At the Granadilla station the substrate is characterised by maerl and coarse sand. The faunal composition is dominated by the amphipod Animoceradocus semiserratus (Spence Bate, 1862) and the polychaetes Chone filicaudata Southern, 1914 and Aponuphis bilineata (Baird, 1870) .

Figures

Fig. 2. Webbnesia maculata gen. et sp. nov., holotype (TFMCBM-AN/246). A. Anterior end, elytra removed and left dorsal cirrus of segment 3 missing.B. Right elytron of segment 21. C. Right cirrigerous parapodium of segment 20, posterior view. D. Left elytragerous parapodium of segment 21, posterior view. E. Notochaetae. F. Upper, middle and lower neurochaetae. Scale bar: A= 1.3 mm; B = 1.9 mm; C–D = 0.4 mm; E–F = 40 µm.

Fig. 3. Webbnesia maculata gen. et sp. nov., holotype (TFMCBM-AN/246). A. Complete specimen, dorsal view. B. Anterior end, dorsal view. C. Complete specimen, ventral view. D. Posterior end, ventral view. Scale bar: A, C = 2 mm; B = 0.6 mm; D = 0.8 mm.

Fig. 4. Webbnesia maculata gen. et sp. nov., holotype (TFMCBM-AN/246). A. Left elytron of segment 21. B. Elytral margin with part of pigmented patch. C. Eggs within parapodium. D. Right cirrigerous parapodium of segment 20, with eggs in basal part. Scale bar: A = 1.6 mm; B–C = 200 µm; D = 0.5 mm.

Fig. 5. Webbnesia maculata gen. et sp. nov., holotype (TFMCBM-AN/246). Distal part of neuropodium (posterior view), showing shorter rounded postchaetal lobe and elongate prechaetal acicular lobe with minute supra-acicular process (arrow). Scale bar = 70 µm.

Fig. 6. Webbnesia maculata gen. et sp. nov., holotype (TFMCBM-AN/246). A. Notochaetae. B. Upper, middle and lower neurochaetae. C. Distal part of upper and middle neurochaetae. D. Distal part of lower neurochaetae. Scale bar: A, C–D = 40 µm; B = 20 µm.