Amaeana angulus, 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 : 27-29

Amaeana angulus sp. nov.

Figures 3 F–H, 14

Amaeana trilobata .— Hutchings & Glasby 1986 (in part): 321–323, Fig. 1 f–i.

Material examined. Holotype AM W.13640 (coll. Australia, Victoria, Townsend Pt, Corner Inlet, 0.5 m deep, in Zostera sp., 16.Dec.1976): complete specimen, 20 mm long, 3 mm maximum width; slides: notopodium, segment 3; neuropodium, segment 25.

Additional material examined. AM W.16116: coll. off Patterson River, 38°16'18"S, 144°41'30"E, 10.Jun.1971. AM W.16126: coll. off Patterson River, 38°16'18"S, 144°41'30"E, 2.Nov.1972. AM W.16115: coll. Port Phillip Bay, 38°4'42"S, 144°42'54"E, 10.Feb.1970. AM W.16127: coll. off Patterson River, 38°16'18"S, 144°41'30"E, 2.Nov.1972. AM W.199014: coll. South Australia, Streaky Bay, 32°35'S, 134°3'E, 13.Mar.1979. AM W.199019: coll. Tasmania, 4km north east of Beaching Bay, Maria Island, 42°35'24"S, 148°11'12"E, 25.Mar.1970. AM W.199029: coll. New South Wales, Botany Bay, 33°58'11"S, 151°11'9"E, 31.Jan.1975.

Type locality. Australia, Victoria, Townsend Point, Corner Inlet, 38°47'31"S, 146°32'26"E, 0.5 m.

Description. Holotype complete specimen, 20 mm long, 3 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 and with rectangular, distinctly wider than long mid-dorsal process; prostomium covering segment 1 laterally and terminating laterally to lower lip, near mouth ( Fig. 14 A–C, E–I). Three types of buccal tentacles, short ones thin, uniformly cylindrical; intermediate tentacles distally spatulate; long buccal tentacles progressively widening towards clearly marked subdistal inflation, with short and pointed tip ( Fig. 14 D).

Peristomium restricted to lips, upper lip almost circular, folded into three lobes; lower lip short, rectangular to crescent-like ( Fig. 14 A–C, E–I).

Body distinctly swollen anteriorly, from segment 3, progressively broader until segments 7–8, then progressively narrower until segment 10, and subsequently of relatively uniform width through posterior body, tapering to pygidium ( Fig. 14 A–C, E–I); achaetous gap between termination of notopodia and beginning of neuropodia, corresponding to segments 13–20, almost twice as long as region with notopodia, with poorly marked segmentation and fragile, with thin body wall dorsally ( Fig. 14 A–C, E).

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. 14 A–C, E–I). Ventrum highly glandular, covered with small papillae, arranged in paired ventro-lateral pads on segments 2–15; papillae larger and more numerous on anterior segments, covering segmental annulations, becoming progressively less conspicuous on segments 12–15, only present on posterior annulation of each segment and progressively less numerous. Subsequently with smooth body wall, with paired longitudinal crests bordering mid-ventral groove through posterior body ( Fig. 14 A–C, E–I).

Notopodia extending through 10 segments, until segment 12; elongate, cylindrical, with equal sized lobes and elongate and distally blunt tips ( Fig. 14 A–B, E–H). Acicular notochaetae in both rows, nearly alimbate capillaries, wings not visible under higher magnifications of light microscopy ( Fig. 3 F–G).

Neuropodia present from segment 21, laterally to mid-ventral groove, on outer margins of longitudinal crests; neurochaetae as 4–5 thin, distally tapered spines, with knob-like tips ( Fig. 3 H).

Nephridial and genital papillae at anterior bases of all notopodia, enlarged on segments 6–10. Pygidium smooth, ventral papilla absent.

Remarks. Specimens from several localities around Australia were identified as A. trilobata , mostly due to the presence of 10 pairs of notopodia ( Hutchings & Glasby 1986). However, they differ from the specimens of A. trilobata from the type locality described above in several other characters important to the taxonomy of the genus, such as the morphology of the mid-dorsal prostomial process and the long buccal tentacles, the extensions of the ventro-lateral glandular pads on anterior segments and the achaetous gap between termination of notopodia and beginning of neuropodia, and the number of neuropodial spines per neuropodium, together with their morphology. For these reasons, material from South Australia and Queensland previously identified as A. trilobata is herein described as two new species, A. angulus sp. nov. and A. ellobophora sp. nov. (see below), respectively, and we suspect more new species will be found when material from other regions of Australia is examined. However much of the material which has been collected during ecological surveys is posteriorly incomplete and therefore generically unidentifiable.

The prostomial process is short and rounded among members of A. trilobata , while in specimens of A. angulus sp. nov. it is distinctly wider, rectangular (compare our Fig. 2 A, I, for A. trilobata , and Fig. 14 B, G, for A. angulus sp. nov.). The long buccal tentacles of members of A. trilobata are distally spatulate, as are the intermediate ones, while in A. angulus sp. nov. the intermediate buccal tentacles are spatulate, but the long ones are more specialised, inflated just below the short tapering tips (compare Figs 2 E and 14D).

In members of A. trilobata , the ventro-lateral glandular pads extend to segment 12, the same segment on which notopodia terminate, although papillae are progressively less abundant from segment 8. In contrast, in members of A. angulus sp. nov. the ventro-lateral pads extend beyond the termination of notopodia, through segment 15, with papillae becoming progressively fewer from segment 12 (compare Figs 2 C, F and 14A, C, E).

In regards to the beginning of neuropodia, specimens of A. trilobata have an achaetous gap of 3 segments between termination of notopodia and the first pair of neuropodia, corresponding to segments 13–15, while in members of A. angulus sp. nov. this region is distinctly longer, through 8 segments, between segments 13–20. Hutchings & Glasby (1986) reported this region as 3–8 segments long in Australian specimens, however, as already discussed, we believe these authors examined material of several different species.

Members of A. trilobata have 7–8 spines per neuropodium and these are straight, except for a short, thinner and slightly hooked tip, while in members of A. angulus sp. nov. there are 4–5 spines per neuropodium, also straight, but with a knob-like tip (compare Fig. 3 B and 3I). Hutchings & Glasby (1986) reported a variation of 3–15 spines per neuropodium among Australian material, which may indicate, again, that more species are present in other regions of Australia.

Amaeana angulus sp. nov. also shares some characters with several other species in this genus, as discussed along the present paper in the Remarks of those species (see above and below).

Etymology. The epithet “ angulus ” is the Latin for “corner”, as a reference to the type locality, Corner Inlet.

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 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.

FIGURE 14. Amaeana angulus sp. nov., holotype AM W. 13640. A, entire worm, left lateral view (anteriorly). B – C, anterior end, dorsal and ventral views, respectively. D, buccal tentacles. E – F, anterior end, left and right lateral views, respectively. G – I, close ups of the anterior end, dorsal, left ventro-lateral and ventral views, respectively. Numbers refer to segments; ll = lower lip, P = basal part of prostomium; PP = mid-dorsal prostomial process; ul = upper lip; * = distal part of prostomium. Scale bars: A = 1.5 mm; B – C, F = 0.7 mm; D = 0.5 mm; E = 1 mm; G – I = 0.5 mm.