Amaeana crassispinulata, 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 : 24-27

Amaeana crassispinulata sp. nov.

Figures 12–13

Material examined. Holotype AM W.47365. (coll. 9.Oct.1978, by A. Jones & C. Short): complete specimen, damaged posteriorly, 7 mm long, 1 mm wide; slides: notopodium, segment 6; anterior neuropodium; posterior neuropodia (3 segments).

Type locality. Australia, Queensland, Great Barrier Reef, Lizard Island lagoon, 14°40'S, 145°28'E, airlifted between bommies at entrance, 18 m.

Description. Holotype complete but posterior segments slightly damaged, 7 mm long, 1 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 with curved margins, mid-dorsal process not clearly delineated; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Figs 12 A–B, D–G; 13A–F). Buccal tentacles missing on specimen.

Peristomium restricted to lips, upper lip higher than broad, not clearly folded into three lobes; lower lip short, rounded, button-like ( Figs 12 A–B, D–G; 13A–F).

Body distinctly swollen anteriorly, progressively broader until segments 7–8, then gently tapering until segment 12, more abruptly tapering until segment 29, and cylindrical abdominal segments of relatively uniform width to posterior end ( Figs 12 A–G; 13A–F); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 13–20, slightly longer than region with notopodia, with poorly marked segmentation and fragile, thin body wall dorsally ( Figs 12 A–B, D–G; 13A–C).

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 until near ventral edge of lower lip ( Figs 12 A, D–G; 13A–F). Ventrum highly glandular, covered with small papillae, arranged in paired ventro-lateral pads on segments 2–12; papillae larger and more numerous on anterior segments, progressively less conspicuous on segments 8–12, then smooth body wall, with mid-ventral groove through posterior body, longitudinal bordering crests not conspicuous ( Figs 12 A–B, D–G; 13A–F).

Notopodia extending through 10 segments, until segment 12, last two pairs distinctly shorter, especially last one; elongate, cylindrical notopodia, with equal sized lobes and elongate and distally blunt tips ( Figs 12 A–B, D–F; 13A–F). Acicular notochaetae, nearly alimbate capillaries, wings not visible under higher magnifications of light microscopy ( Fig. 13 G).

Neuropodia present from segment 21, laterally to mid-ventral groove ( Fig. 12 A–G); neurochaetae as single spine per neuropodium throughout, spines basally broader, slightly bulbous, with short, distally truncate tip protruding from body wall ( Figs 12 A–G; 13H–I).

Nephridial and genital papillae at anterior bases of notopodia, those of mid-thoracic segments slightly larger, papillae apparently absent on last two pairs of notopodia ( Figs 12 D–F; 13A–B). Posterior end damaged, and details of the pygidium not clear, apparently crenulate and with no ventral papilla present.

Remarks. Amaeana crassispinulata sp. nov., closely resembles other species of Amaeana , as well as members of all species of Lysilla and some Polycirrus , in regards to the general morphology of the body and, more specifically, the anterior end. The most distinctive character of A. crassispinulata sp. nov., which distinguishes its members from all other species of Amaeana , is the presence of a single neuropodial spine per neuropodium throughout, with a bulbous base and truncate tip.

Of all species of Amaeana , only members of A. apheles ( Hutchings, 1974) and A. yirrarn Hutchings, 1997 have 1–2 stout spines per neuropodium throughout ( Table 1), but those are easily differentiated from the spines of members of A. crassispinulata sp. nov., as they are distally tapered, as in all other species in this genus. Etymology. The name “ crassispinulata ” refers to the morphology of the neuropodial spines, from the Latin “crassus” = stout (plural “crassi”) and “spinulata” = with spines.

Figures

FIGURE 12. Amaeana crassispinulata sp. nov., holotype AM W. 47365. A – B, entire worm, ventral and dorsal views (anteriorly). C, posterior end, ventral view. D, G, anterior end, right and left lateral views, respectively; arrows point to last notopodium (upper) and first neuropodium (lower). E – F, entire worm right and left lateral views, respectively. Scale bars: A – B, D – F = 0.4 mm; C = 0.2 mm; G = 0.3 mm.

FIGURE 13. Amaeana crassispinulata sp. nov., holotype AM W. 47365. A – D, anterior end, left and right lateral, ventral and dorsal views, respectively. E – F close ups of the anterior end, ventral and dorsal views, respectively. G, notochaetae, segment 6. H, anterior neuropodium. I, posterior neuropodia. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; ul = upper lip; * = distal part of prostomium. Scale bars: A – D = 0.2 mm; E = 0.15 mm; F = 0.1 mm; G – H = 10 µm; I = 20 µm.