Paradoneis andreae, Sikorski, Andrey, 2017

Sikorski, Andrey, 2017, The Paraonidae (Annelida: Sedentaria) from Norway and adjacent seas, with two new species, four new records, and a redescription of Paraonides nordica Strelzov, 1968 based on type material, Zootaxa 4320 (1), pp. 41-67 : 56-58

Paradoneis andreae n. sp.

( Figs 7 , 8 )

Material examined. 2290 Tromsøsundet S15; 69.6573°N – 18.8813°E; 38 m; 23.04.2002; holotype ( ZMBN 116015), three paratypes ( ZMBN 116016) and 26 specimens. 2876 Finnmark 592; 70.0650°N – 29.0663°E; 88 m; 13.09.2003; four paratypes ( ZMBN 116017) and 16 specimens.

Description. Holotype longest specimen, complete, 14.5 mm long for 116 chaetigers, 0.4 wide at tenth chaetiger level. Branchial region slightly flattened ( Fig. 8A ), composed of wider than long segments; postbranchial region cylindrical, segments progressively longer than wide, ventrally divided in four rings ( Fig. 8D ); posterior region (last 12 chaetigers), cylindrical, composed of very short, almost discoidal segments. Preserved specimens light brown or yellowish. Prostomium with rounded tip, one and a half times as long as wide; antennae or insertion scar totally absent; eyes and apical sensory organ absent ( Fig. 7A , 8A, B ). Mouth ventrally oriented; anterior and lateral lips poorly developed; posterior lip extending to anterior margin of second chaetiger. Nuchal organs obliquely oriented, in a dorsolateral position ( Fig. 8B ); secondary ciliary organs absent. Prebranchial region with three chaetigers ( Fig. 7A , 8A ); branchiae extending to chaetiger 20 (to chaetiger 17–22, mean: 18.57, SD: 1.07, n: 21); progressively increasing in length from beginning to chaetiger 6, remaining branchiae similar in length to distance between bases, except the last two pairs, which are shorter; branchiae lanceolate ( Fig. 8A ), bent forward, bearing long ciliation on outer margin ( Fig. 7A, B , 8C ). Notopodial postchaetal lobe short and blunt, almost papiliform in prebranchial chaetigers ( Fig. 7A ); in branchial chaetigers, lobes progressively larger and subulate ( Fig. 7A, B , 8C ); in postbranchial chaetigers width progressively decreasing and length increasing ( Fig. 7C ), becoming cirriform in posterior-most chaetigers ( Fig. 7D ). Neuropodial postchaetal lobes as low ridges, of even height ( Fig. 7B–D ). Chaetae of pre- and branchial segments in dense fascicles, arranged in two rows in both noto- and neuropodia ( Figs 7A, B , 8A ); fewer and arranged in single row in post–branchial chaetigers ( Fig. 7C, D ); notochaetae gently curved, one and a half as long as body width in pre- and branchial chaetigers ( Fig. 7A, B ), numbering 15–20 in prebranchial chaetigers, 20–25 in branchial ones; notochaetae straight and thinner, twice longer than body width in postbranchial chaetigers, numbering 4–5 ( Fig. 7C, D ); forked notochaetae present from chaetiger 4, numbering 1–2 per fascicle ( Fig. 7B–D ), dorsal tine longer, bearing minute spines on internal surface, shaft smooth ( Fig. 7E ); neurochaetae in pre- and branchial chaetigers slightly thicker and shorter than corresponding notochaetae, narrowly limbate, and slightly geniculate, numbering about 40 in prebranchial chaetigers and about 50 in branchial ones ( Fig. 7A, B ); neurochaetae capillary in postbranchial chaetigers, numbering up to 12 ( Fig. 7C ); neuropodial fascicles from chaetiger 78 onwards (from chaetiger 48–76, mean: 66.75, SD: 9.72, n: 8) bearing a single spine-like chaeta with curved tip, clearly thicker than capillaries of the same fascicle, absent from the last two chaetigers ( Figs 7D, F , 8E ). Pygidium rounded, bearing a pair of flat pygidial cirri on a ventral position and a pair of shorter ones dorsally ( Fig. 7G ).

Remarks. Within the genus Paradoneis only P. eliasoni Mackie, 1991 , widely distributed through North Atlantic and also recorded in this work, and P. strelzovi de León-González & Díaz-Castañeda, 2011 , from Baja California, bear single spine-like neurochaetae in posterior chaetigers and forked modified notochaetae ( Mackie 1991; Aguirrezabalaga & Gil 2009; de León-González & Díaz-Castañeda 2011). However, these two species bear fewer branchiae; P. eliasoni possesses up to 12 pairs ( Mackie 1991; Aguirrezabalaga & Gil 2009) and P. strelzovi has up to seven (de León-González & Díaz-Castañeda 2011). Apart of the number of branchiae, P. strelzovi can be told apart by the shape of the notopodial postchaetal lobes (almost papiliform in P. andreae n. sp., distinctly triangular in P. strelzovi ) and the type of branchiae, which have ciliated outer margins in P. andreae n. sp. and are smooth in P. strelzovi (de León-González & Díaz-Castañeda 2011) . Paradoneis eliasoni also differs in the shape of the branchiae, which have ciliation both on outer and inner margins ( Aguirrezabalaga & Gil 2009).

Etymology. The new species is dedicated to Andrea, daughter of the first author.

Figures

FIGURE 7. Paradoneis andreae n. sp. Holotype. A. Anterior end, lateral view; B. Right parapodium of chaetiger 10, anterior view; C. Left parapodium of chaetiger 69, anterior view; D. Left parapodium of chaetiger 110, anterior view; E. Forked notochaetae of chaetiger 27; F. Detail of spine-like neurochaeta and ventral capillary neurochaetae of chaetiger 110; G. Pygidium. Scale bar: A: 0.3 mm. B, C: 95 µm. E, D: 30 µm. G: 0.15 mm.

FIGURE 8. Paradoneis andreae n. sp. SEM micrographs, specimen from 2290 Tromsøsundet. A. Anterior end, dorsolateral view. B. Detail of the same; C. Chaetigers 7 to 12, lateral view; D: Postbranchial chaetigers, lateral view; E: detail of posterior neuropodia showing capillary and spine-like neurocahetae. Abbreviations: br: branchia; cp: capillary chaeta; no: nuchal organ; npl: notopodial postchaetal organ; sl: spine-like neurochaeta. Scale bar: A: 0.3 mm; B: 50 µm; C: 0.1 mm; E: 20 µm.