Amaeana trilobata ( Sars, 1863 )

Nogueira, João Miguel De Matos, Carrerette, Orlemir & Hutchings, Pat, 2015, Review of Amaeana Hartman, 1959 (Annelida, Terebelliformia, Polycirridae), with descriptions of seven new species, Zootaxa 3994 (1), pp. 1-52 : 9-10

Amaeana trilobata ( Sars, 1863)

Figures 2 , 3 A–B

Polycirrus trilobatus Sars 1863: 305 .

Amaeana trilobata .— Holthe 1986: 159 –160; Fig. 74.? Amaeana trilobata .— Fauvel 1927: 285 –286: Fig. 99a–e.

Material examined: NMO C 3207a [coll. Christiansund, northern Norway, 50 ft (91.44 m), coll. & det. M. Sars]: 1 incomplete spec., 12 mm long, 3.5 mm wide at seg. 5, maximum width of body. NMO C 3207b [coll. Slaatholmen i Lofoten (Lofoten Islands, northern Norway), 90 ft (~ 164.6 m)]: 2 incomplete specimens, tuft of buccal tentacles, and 2 segs, separated from each other and from main body, and not inside separate vials; LECTOTYPE: ~ 31 mm long, ~ 1.9 mm wide at seg. 6, maximum width of body, slide: neuropodium, seg. 45; other spec. anterior fragment, dissected and torn apart, with 7 pairs of notopodia, in relatively good shape, ~ 5 mm long, 2 mm wide (uniform); slide: notopodium, segment 5. NMO C 3208 [coll. Drøbak (Oslo fjord)]: 2 incomplete specs and additional vial with one notopodium, one specimen in excellent state of preservation, 22 mm long, 4 mm wide at seg. 7, widest point of body, another one anterior fragment in relatively good state of preservation, 11 segs, 8.5 mm long, 4.8 mm wide at seg. 7, maximum width of body.

Type locality. Northern Norway, Slaatholmen i Lofoten, 91.44 m.

Description. Lectotype incomplete specimen, apparently only posteriormost segments and pygidium missing, ~ 31 mm long, ~ 1.9 mm wide at segment 8, widest point of body.

Prostomium at base of upper lip, both basal and distal parts developed, basal part as thickened crest, distal part with large, flaring lobes and also oval to rectangular mid-dorsal process; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Fig. 2 A–C, F–I). Three types of buccal tentacles, short ones thin, uniformly cylindrical, intermediate and long buccal tentacles distally broader, spatulate ( Fig. 2 E).

Peristomium restricted to lips, upper lip almost circular, slightly higher than broad, folded into three lobes; lower lip short, rectangular, distinctly wider than long ( Fig. 2 A–C, F–I).

Body progressively broader until segment 7, then of uniform width through segment 16, abruptly tapering to narrower uniformly cylindrical posterior body, beginning from segment 19 ( Fig. 2 A–D, F–I); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 13–15, with poorly marked segmentation and fragile, with thin body wall dorsally ( Fig. 2 A–C, F), much shorter than region with notopodia.

Segments biannulated, segment 1 short, visible dorsally and ventrally, laterally covered by expanded prostomium; segment 2 narrower and shorter than following segments, with large pentagonal mid-ventral shield at beginning of mid-ventral groove, extending anteriorly through segment 1 until near ventral edge of lower lip ( Fig. 2 A–C, F–I). Ventrum highly glandular, covered on small papillae, arranged in paired ventro-lateral pads on segments 2–12; papillae larger and more numerous on anterior segments, papillae progressively less conspicuous on segments 8–12, then smooth body wall, with paired longitudinal crests bordering mid-ventral groove through posterior body ( Fig. 2 B–C, F–H).

Notopodia extending through 10 segments, until segment 12; elongate, cylindrical notopodia, with equal lobes and elongate and distally blunt tip ( Fig. 2 A–C, F–I). Acicular notochaetae in both rows, nearly alimbate, wings not visible under higher magnifications of light microscopy ( Fig. 3 A).

Neuropodia present from segment 16, laterally to mid-ventral groove, on outer margins of longitudinal crests ( Fig. 2 D, J). Neurochaetae up to 7–8 thin, distally tapered spines, with thinner and hooked tip ( Fig. 3 B).

Nephridial and genital papillae at anterior bases of all notopodia, first pairs and also last one distinctly shorter. Pygidium unknown.

Remarks. We received two lots of Amaeana trilobata on loan from the NMO, C3207 and C3208. Both lots have been examined and identified by M. Sars, but only C3207 was used for the original description (A.-H. Rönning and E. Oug, personal communication); for this reason we designated the lectotype from this sample, although the description above is based on specimens from both lots.

Amaeana trilobata was described as having 10 pairs of notopodia and neuropodia with acicular spines, from material from the Norwegian coast ( Sars 1863). Subsequently, this species was reported from several localities around the world ( Fauvel 1927; Imajima & Hartman 1964; Day 1967, 1973; Hartman & Fauchald 1971; Hutchings 1977; Holthe 1986; Hutchings & Glasby 1986; Blankensteyn 1988; Hartmann-Schröder 1996). However, in this paper we describe two new species from Australian material which had previously been identified as A. trilobata ( Hutchings & Glasby 1986) , A. angulus sp. nov., for specimens from Victoria, and A. ellobophora sp. nov., from Queensland, and we suspect several other new species will be described if material identified as A. trilobata from other localities around the world is examined, except, perhaps, for those records from the Northern Atlantic.

Figures

FIGURE 2. Amaeana trilobata, NMO C 3208: A – C, anterior end, dorsal, right lateral and ventral views, respectively; arrow in C points to first neuropodium. D, mid-abdominal segments, left lateral view. E, buccal tentacles. F, anterior end, right lateral view; arrows point to nephridial / genital papillae. G – I, close ups of the anterior end, ventral, right lateral and dorsal views, respectively. J, mid-abdominal segments, right lateral view; arrows point to neuropodia with protruding spines. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; PP = mid-dorsal prostomial process; ul = upper lip; P * = distal part of prostomium. Scale bars: A = 0.8 mm; B, E – F = 0.5 mm; C = 0.7 mm; D, H, J = 0.4 mm; G = 0.3 mm; I = 0.2 mm.

FIGURE 3. Chaetae. Amaeana trilobata NMO C 3208: A, notochaetae, segment 5. B, neurochaetae, segment 45. Amaeana breviachaeta sp. nov., holotype AM W. 46526: C, notochaetae, segment 8. D – E, neurochaetae, segments 21 and 27, respectively. Amaeana angulus sp. nov., holotype AM W. 13640: F – G, notochaetae, segment 3. H, neurochaetae, segment 25. Scale bars: A, G – H = 80 µm; B, D – E = 10 µm; C = 20 µm; F = 150 µm.