Amaeana dampierensis, Nogueira, João Miguel De Matos, Carrerette, Orlemir & Hutchings, Pat, 2015

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 : 43

Amaeana dampierensis sp. nov.

Figures 24 D–E, 25

Material examined: Holotype: AM W.47405, coll. King Point, East Lewis Island, Western Australia, Australia, 03.Mar.2001, 13 m. Paratypes: AM W.27469, same locality as holotype, 3 specimens in poor condition, one (AM W.47405) dissected for the preparation of slides; slides: notochaetae, segment 7; neurochaetae, segment 29. AM W.21872 (coll. 31–33 km NW Kurumba, Gulf of Carpentaria, Australia, 17°17'18"S, 140°36'30"E, Apr.1994): 3 specimens in poor condition, incomplete and damaged. AM W.21871 (coll. 31–33 km NW Kurumba, Gulf of Carpentaria, Australia, 17°17'15"S, 140°36'36"E, Apr.1994): 1 specimen in poor condition, incomplete and damaged.

Type locality. King Point, East Lewis Island, Western Australia, Australia, 20°38'17.4"S, 116°38'23.4"E, 13 m.

Description: Holotype incomplete, 7 mm long, 2 mm wide at segment 8, maximum width 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, prostomial process not clearly delineated; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Fig. 25 A–F). Few buccal tentacles remaining, of two types, both relatively short, short ones thin, uniformly cylindrical, intermediate tentacles distally spatulate, long tentacles apparently absent ( Fig. 25 F).

Peristomium restricted to lips, upper lip higher than broad, elliptical, slightly convoluted; lower lip short, rounded to rectangular ( Fig. 25 A–F). Body progressively broader until segment 5, then of uniform width through segment 10, progressively tapering on segments 11–14, and again of relatively uniform width through posterior body, narrower than anterior segments ( Fig. 25 A–F); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 14 through 26–27, twice as long as region with notopodia, with poorly marked segmentation and fragile, with thin body wall dorsally.

Segments biannulated, segment 1 short, visible dorsal 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 to near ventral edge of lower lip ( Fig. 25 A–F). Ventrum highly glandular, covered with small papillae, arranged on paired ventro-lateral pads on segments 2–13; papillae larger and more numerous on anterior segments, until segment 8, covering both segmental annulations, papillae progressively less conspicuous on segments 9–13, only present on posterior annulation of each segment and progressively less numerous, then smooth body wall, with paired longitudinal crests bordering mid-ventral groove through posterior body ( Fig. 25 A–E).

Notopodia extending through 11 segments, until segment 13, last pair distinctly shorter; elongate, cylindrical notopodia, with equal sized lobes and elongate and distally blunt tips ( Fig. 25 A–D, F). Acicular, narrowly-winged notochaetae in both rows, wings not visible under higher magnifications of light microscopy ( Figs 24 D; 25G).

Neuropodia present from segments 26–27, laterally to mid-ventral groove, on outer margins of longitudinal crests. Neurochaetae as 4–5 thin, distally tapered spines, apparently with thinner, flattened tip ( Fig. 24 E).

Nephridial and genital papillae at anterior bases of all notopodia, all short ( Fig. 25 B–D). Pygidium unknown.

Remarks. The number of pairs of notopodia is one of the most important characters to distinguish between species of Amaeana , and among the currently known species in this genus there is only one other with 11 pairs of notopodia, A. brasiliensis sp. nov., described below. The differences between members of A. dampierensis sp. nov. and A. brasiliensis sp. nov., are discussed in the Remarks of the latter species.

Members of this species were first identified as A. antipoda because of having 11 pairs of notopodia, but in this species the achaetous gap between termination of notopodia and beginning of neuropodia extends for 6–8 segments, neuropodia beginning from segments 19–21 and with 2–3 spines each ( Hutchings & Glasby 1986), while in A. dampierensis sp. nov., the achaetous gap is far longer, extending for 13–14 segments, neuropodia beginning from segments 26–27, and each bearing 4–5 spines. As said above, we tried to examine the type material of A. antipoda to compare with A. dampierensis sp. nov., but we could not locate it or any material from the type locality.

Figures

FIGURE 24. Chaetae. Amaeana yirrarn paratype AM W. 21888. A, notochaetae, segment 11. B, close up of the notochaetae from posterior row, segment 11. C, neurochaetae, segment 36. Amaeana dampierensis sp. nov. AM W. 47405. D, tips of notochaetae from posterior row, segment 7. E, neurochaetae, segment 29. Amaeana brasiliensis sp. nov. paratype MZUSP 2726. F – G, notochaetae, segment 4. H, neurochaetae, segment 34. I, neurochaetae, segment 36. Scale bars: A = 50; B – D, H – I = 5 µm; E = 10 µm; F = 40 µm; G = 2 µm.

FIGURE 25. Amaeana dampierensis sp. nov. holotype AM W. 47405. A – C, anterior end, ventral, right and left lateral views, respectively. D – F, close ups of the anterior end, left lateral, ventral and dorsal views, respectively; arrows point to nephridial / genital papillae. G, notochaetae, segment 7. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; ul = upper lip; P * = distal part of prostomium. Scale bars: A – C = 1.5 mm; D – F = 0.5 mm; G = 0.15 mm.