Amaeana apheles ( Hutchings, 1974 )

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 : 20-24

Amaeana apheles ( Hutchings, 1974)

Figures 9 , 10 and 11

Lysilla apheles Hutchings 1974: 190 –191, Fig. 5 A;— Hutchings 1977: 10 –11;— Hutchings & Murray 1984: 90. Amaeana apheles .— Hutchings & Glasby 1986: 321, Figs 1 C–E; 12A.

Material examined. Holotype: AM W.5239: incomplete specimen, with 11 abdominal segments, in excellent state of preservation, 12 mm long, ~ 2.5 mm wide at posterior thorax. Paratypes: AM W.5237: incomplete specimen, in good state of preservation, ~ 14 mm long, ~ 1.8 mm wide. AM W.5238: incomplete specimen in good state of preservation, ~ 15 mm long, ~ 2 mm wide. All type material collected from—Australia, New South Wales, Wallis Lake, 32°17'S, 152°29'E, Dec.1970, coll. by P. Dixon & K. O’Gower, in seagrass beds in shallow water.

Additional material examined. AM W.5384 (Queensland, Mary River, Kangaroo Island, Hervey Bay, 25°25'S, 152°56'E, Dec.1971): 2 specimens, 1 of which complete. AM W.29203 (Queensland, Mary River, Kangaroo Island, Hervey Bay, 25°25'S, 152°56'E, Dec.1971): complete, in excellent state of preservation; slides: notopodium, segment 9; anterior and posterior neuropodia. AM W.10864 ( Australia, Queensland, Nerang River, Gold Coast, 28°6'S, 153°18'E, 1975): mounted on SEM pin. AM W.19333 ( Australia, New South Wales, Hawkesbury River, near Juno Head, 33°34'S, 151°15' E, 12.Jan.1977): mounted on SEM pin.

Type locality. Australia, New South Wales, Wallis Lake, 32°17'S, 152°29'E, shallow water.

Description: Holotype incomplete specimen, 12 mm long, ~ 2.5 mm wide at posterior thorax, maximum width of body; longest specimen examined ~ 15 mm long, ~ 2 mm wide.

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 short, rounded to squared mid-dorsal process; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Figs 9 A–H; 10A–H). Three types of buccal tentacles, short ones thin, uniformly cylindrical; intermediate tentacles distally spatulate, with convolute margins; long buccal tentacles progressively widening towards subdistal cylindrical inflation, collar-like, with relatively long pointed to distally blunt tip, as wide as tentacle basally to collar-like inflation ( Fig. 9 A–H).

Peristomium restricted to lips, upper lip almost circular, usually folded into three lobes; lower lip short, buttonlike, rectangular to crescent-shaped ( Figs 9 A–H; 10A–H).

Body anteriorly swollen, progressively broader until segments 10–11, then of uniform width until segments 19–20, tapering on segments 20–23, and again of relatively uniform width through posterior body, distinctly narrower than anterior segments ( Figs 9 A–H; 10A–F; 11G); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 12–13 to 21–22 (9–10 segments), twice as long as region with notopodia, with poorly marked segmentation and fragile, with thin body wall dorsally ( Figs 9 B; 10A–C).

Segments biannulated, segment 1 short, visible dorsally and ventrally, laterally covered by expanded prostomium; segment 2 narrower and shorter than following segments, with small, pentagonal mid-ventral shield at beginning of mid-ventral groove, extending anteriorly through segment 1 until near ventral edge of lower lip ( Figs 9 A–H; 10A–H). Ventrum highly glandular, covered on small papillae, arranged on paired ventro-lateral pads on segments 2–12; papillae larger and more numerous on anterior segments, progressively less numerous on segments 11–12, still conspicuous on both parts of each segment ( Figs 9 A–F, H; 10A–B, D–E, H).

Notopodia starting from segment 3 and extending through 10 segments, until segment 12, in holotype, some specimens with 9 pairs of notopodia only; elongate, cylindrical notopodia, with equal sized lobes and elongate, distally blunt tip ( Figs 9 A–I; 10A–G; 11A–B). Notochaetae as nearly alimbate capillaries in both rows, wings not visible under higher magnifications of light microscopy ( Fig. 9 I–J), as short and fine hairs under SEM, closely resembling pinnate chaetae, but with finer hairs in oblique tiers ( Fig. 11 A–E).

Neuropodia present from segments 23–24, laterally to mid-ventral groove, on outer margins of longitudinal crests; neurochaetae as 1–2 thick, distally sharp spines, tips somewhat narrower and slightly hooked ( Figs 9 K; 11F–I).

Nephridial and genital papillae at anterior bases of all notopodia, larger on segments 5–10 ( Figs 9 B, D–E; 10A–B, D–E). Pygidium with rounded ventral papilla.

Remarks. This taxon was originally described as a species of Lysilla , due to the holotype being posteriorly incomplete, with few segments after termination of notopodia, not presenting neuropodia ( Hutchings 1974). Subsequently, complete specimens were found and the species was correctly transferred to Amaeana ( Hutchings & Glasby 1986) .

Members of A. apheles are characterised by having 1–2 stout, distally sharp spines per neuropodium. In contrast to the other species in this genus, members of A. apheles present slight variation on the number of pairs of notopodia present, 9–10 pairs.

Members of A. yirrarn also have 1–2 spines per neuropodium, but these species are distinguished by the latter having 12 pairs of notopodia, instead of 9–10, as in A. apheles . There is also a difference on the extension of the achaetous gap between termination of notopodia and beginning of neuropodia between these species, although with some overlapping, as this gap extends for 7–9 segments in A. yirrarn , and 9–10 in A. apheles .

Besides A. yirrarn , three other species have a number of spines per neuropodium similar to that of A. apheles , A. crassispinulata sp. nov., A. hsiehae sp. nov., and A. brasiliensis sp. nov., all these species described herein. However, those spines are basally wider and distally truncate in A. crassispinulata sp. nov. (see below), tapered, but not as sharp in A. hsiehae sp. nov., described above, and distally blunt or with oblique tip in A. brasiliensis sp. nov.; in addition, this latter. In addition, this latter species also has a different number of pairs of notopodia (see below).

Figures

FIGURE 1. Amaeana ellobophora, paratype 1 AM W. 10341, with egg cocoons: A, entire worm, dorsal view. B, anterior end, dorsal view. Scale bars: A = 0.5 mm; B = 0.3 mm.

FIGURE 5. Amaeana hsiehae sp. nov., ASIZW 0000935. A – D, entire worm, right ventro-lateral, right lateral, left lateral and left dorso-lateral views, respectively; arrows point to beginning of neuropodia; E – F, progressively closer views of the anterior end, ventral view; G – H, thorax, right and left lateral views, respectively; I – K, close ups of the anterior end, left dorso-lateral, ventral and right lateral views, respectively; L, posterior end, left dorso-lateral view; M, close up of the anterior end, left dorsolateral view; N, abdominal segments; arrows point to neuropodia; O, posterior end, right ventro-lateral view. Paratype AM W. 47363: P, entire worm, left lateral view (anteriorly); Q, thorax, left lateral view. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; ul = upper lip. Scale bars: A = 0.6 mm; B – D, H = 0.5 mm; E, G = 0.4 mm; F, I – L, N = 0.2 mm; M, O = 0.15 mm; P = 1.5 mm; Q = 1 mm.

FIGURE 9. Amaeana apheles, holotype AM W. 5239. A – C, anterior end, dorsal, right ventro-lateral, and ventral views, respectively. D – F, closer views of the anterior end, left and right ventro-lateral, and ventral views, respectively; arrows point to nephridial / genital papillae. G – H, close ups of the anterior end, dorsal and ventral views, respectively. Specimen AM W. 29203: I – J, notochaetae, segment 9. K, neurochaetae, posterior segment. 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 = 0.7 mm; B – C = 1 mm; D – F = 0.5 mm; G – H = 0.3 mm; I – K = 20 µm.

FIGURE 10. Amaeana apheles, photos D and G from specimen AM W. 10864, all other photos from specimen AM W. 19333. A – C, thorax, right lateral, ventral and dorsal views, respectively. D – E, close ups of the anterior end, left and right lateral views, respectively. F – G, close ups of the anterior end, dorsal view. H, detail of the oral area. 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 – B = 0.7 mm; C = 0.6 mm; D = 0.15 mm; E – F = 0.2 mm; G – H = 0.1 mm.

FIGURE 11. Amaeana apheles, photos A – E from specimen AM W. 19333, photos F – I from specimen AM W. 10864. A, notopodia, segments 9 – 10; B – E, notochaetae, segment 10; F – G, posterior neuropodia; H – I, close up of posterior neuropodia with protruding spines. Scale bars: A = 70 µm; B, I = 10 µm; C – D = 5 µm; E = 4 µm; F = 200 µm; G = 8 µm; H = 20 µm.