Amaeana hsiehae, 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 : 14-17

Amaeana hsiehae sp. nov.

Figures 5 , 6 , 7 and 8

Material examined. Holotype ( ASIZW 0000935): complete specimen, in good state of preservation; slides: notochaetae, segment 6; neurochaetae, segment 21; neurochaetae, posterior segment. Paratypes: ASIZW 0000936: incomplete, in good state of preservation, 13 mm long, 1.2 mm wide; ASIZW 0000937: incomplete, in good state of preservation, 13 mm long, 1 mm wide; ASIZW 0000938: complete, in good state of preservation, but very fragile and full of oocytes, 23 mm long, ~ 4 mm wide; AM W.47362 complete, in good state of preservation, 11 mm long, 0.8 mm wide, mounted on SEM stub; AM W.47363: complete, in good state of preservation, but very fragile and full of oocytes, 31 mm long, ~ 3.5 mm wide; AM W.47364: complete (in two pieces), in good state of preservation, but very fragile and full of oocytes, 34 mm long, ~ 3 mm wide. All type material collected from—Wuijang Estuary, Kinmen Island, Taiwan, 24°25’44.04’’N, 118°18’53.80’’E, small tidal creek, enriched with organic matters, which flows intermittently, muddy substrate (> 60 %) plus debris of oyster shells; intertidal.

Type locality. Taiwan, Kinmen Island, Wuijang Estuary, 24°25’44.04’’N, 118°18’53.80’’E, intertidal.

Description. Holotype complete specimen, 17 mm long, 1 mm wide at segment 8, maximum width of body; paratypes up to 34 mm long and ~ 3.5 mm wide (see above).

Prostomium at base of upper lip, both basal and distal parts developed, basal part as thickened crest, distal part with large flaring lobes, mid-dorsal process not clearly delineated; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Figs 5 A–K, M, P–Q; 7A–I). Buccal tentacles of three types, short ones thin, uniformly cylindrical, except for expanded sphaerical to elliptical tip; intermediate tentacles thin, uniformly cylindrical, also expanded at tip; long tentacles progressively widening at tip, towards clearly marked subdistal cylindrical inflation, with short and pointed tip ( Figs 5 A–K, M, P–Q; 7A–I); all types with ciliated groove only at tips.

Peristomium restricted to lips, upper lip longer than broad, with straight lateral margins, almost rectangular; lower lip short, rounded to rectangular, button-like ( Figs 5 A–K, M, P–Q; 7A–D, F–G, I).

Body progressively broader on segments 3–7, of relatively uniform width until segment 10, tapered on segments 11–18, then of relatively uniform width, with cylindrical segments through mid- and posterior body, tapering near pygidium ( Figs 5 A–Q; 7A–I; 8H–I); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 13–19, with poorly marked segmentation and fragile, with thin body wall dorsally, about same size or slightly longer than region with notopodia ( Figs 5 A–E, G–H, N, P–Q; 7A–B).

Segments biannulated, segment 1 short, visible dorsal and ventrally; segment 2 narrower and shorter than following segments, with relatively large, pentagonal mid-ventral shield at beginning of mid-ventral groove, extending anteriorly through segment 1 until near ventral edge of lower lip, about same length as that of segment 3 and slightly broader ( Figs 5 A–K, M, P–Q; 7A–I). Ventrum highly glandular, covered with small papillae, arranged in paired ventro-lateral pads on segments 2–12; papillae about same size throughout and slightly more numerous on anterior segments; from after termination of notopodia, paired longitudinal crests bordering mid-ventral groove through posterior body ( Figs 5 A–Q; 7A–I; 8A, G–J).

Notopodia extending through 10 segments, until segment 12; elongate, cylindrical notopodia, with equal sized lobes and elongate and distally blunt tips ( Figs 5 A–E, G–I, K, M, P–Q; 7A–I; 8A–C). Pinnate chaetae in both rows, those from posterior row pinnate only on distal half ( Figs 6 A–B; 8A–F).

Neuropodia present from segment 20, laterally to mid-ventral groove, on outer margins of longitudinal crests. Neurochaetae as 2–3 relatively stout, distally tapered spines, slightly expanded subdistally, with short oblique tip; only tips protruding ( Figs 5 A–D, N–P; 6C–E; 8G–L).

Nephridial and genital papillae anterior to bases of all notopodia, those of segments 6–10 larger in sexually mature specimens, at least on females ( Figs 5 P–Q; 7A–F, H–I); several specimens with additional pair of papillae on segment 13. Pygidium crenulate, with slightly larger ventral papilla ( Figs 5 A–D, L, O–P; 8 H–I, M).

Remarks. Amaeana hsiehae sp. nov. is unique among the species of this genus in having pinnate notochaetae in both rows. The only other species of Amaeana with conspicuously pinnate chaetae visible under light microscopy is A. occidentalis , however this latter species only has these chaetae in posterior row of notochaetae, those from anterior row being acicular (see below).

Besides the pinnate notochaetae, Amaeana hsiehae sp. nov. is also characterised by having 10 pairs of notopodia, achaetous gap of 7 segments between termination of notopodia and beginning of neuropodia, and neuropodia bearing 2–3 spines. In addition, the shape of the upper lip of A. hsiehae sp. nov. is unique among species of this genus, nearly rectangular, higher than broad and with almost straight lateral margins.

Five other species of Amaeana share with A. hsiehae sp. nov. the presence of 10 pairs of notopodia, A. apheles , A. angulus sp. nov., A. trilobata , A. ellobophora sp. nov. and A. crassispinulata sp. nov. ( Table 1). Members of A. apheles differ from A. hsiehae sp. nov. in having an almost circular upper lip, a larger achaetous gap between termination of neuropodia and beginning of neuropodia, representing 9–10 segments, and stout, distally sharp spines, while in A. hsiehae sp. nov., in addition to what has been said above, the spines are distally tapered, but not as sharp as those of A. apheles (compare Figs 6 C–E and 9K). Members of A. angulus sp. nov. differ from those of A. hsiehae sp. nov. in having a circular upper lip, slightly larger achaetous gap between termination of notopodia and beginning of neuropodia, extending for 8 segments, and neuropodia with 4–5 spines each. Amaeana trilobata has a shorter achaetous gap between termination of notopodia and beginning of neuropodia, 3 segments only, lacks modified buccal tentacles, has an elliptical upper lip and each neuropodium bears 7–8 spines. Amaeana ellobophora sp. nov., also has a shorter achaetous gap between termination of notopodia and beginning of neuropodia, 5 segments, a nearly circular upper lip, and each neuropodium bears 8–11 spines. Finally, in A. crassispinulata sp. nov., the number of achaetous segments between termination of notopodia and beginning of neuropodia resembles that of A. hsiehae sp. nov., 8 segments, but each neuropodium has a single spine, and these are basally wider and distally truncate, as described below.

Etymology. We dedicate this species to Dr Hwey-Lian Hsieh, from Academia Sinica, Taiwan, who collected the material and invited PH to identify the worms.

Figures

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 6. Amaeana hsiehae sp. nov., holotype ASIZW 0000935. A – B, progressively closer views of the notochaetae of segment 6; C – E, neurochaetae, segments 21 and two consecutive posterior ones, respectively. Scale bars: A = 30 µm; B = 15 µm; C – E = 7 µm.

FIGURE 7. Amaeana hsiehae sp. nov., paratype AM W. 47362. A – B, thorax right and left lateral views, respectively; C – F, anterior end, ventral, right lateral, dorsal and left lateral views, respectively; G, close up of the anterior end, ventral view; H, anterior end, dorsal view; I, anterior end, right ventro-lateral view. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; ul = upper lip; * = distal part of prostomium. Scale bars: A – B, D, H = 200 µm; C, F = 100 µm; E = 150 µm; G, I = 70 µm.

FIGURE 8. Amaeana hsiehae sp. nov., paratype AM W. 47362. A, notopodia, segments 3 – 6; B, notochaetae, segment 3; C – D, notochaetae, segment 7; E – F, close ups of notochaetae from anterior row, segment 7; G, abdominal segments; arrows point to protruding spines; H – I, progressively closer views of the posterior end, left lateral view; J, close up of posterior neuropodia; K – L, tips of neuropodia with protruding spines; M, posterior end, frontal view. Scale bars: A = 100 µm; B, D = 10 µm; C = 15 µm); E = 7.5 µm; F = 2 µm; G = 70 µm; H – I = 200 µm; J = 40 µm; K – L = 1 µm; M = 20 µm.