Amphictene lizardensis, Wong, Eunice & Hutchings, Pat, 2015

Wong, Eunice & Hutchings, Pat, 2015, New records of Pectinariidae (Polychaeta) from Lizard Island, Great Barrier Reef, Australia and the description of two new species, Zootaxa 4019 (1), pp. 733-744 : 735-738

Amphictene lizardensis n. sp.

( Figs 1–3 )

Material examined. Holotype: AM W.47432, MI QLD 2194, Lizard Island, Watson’s Bay, 14°39'26"S 145°27'3"E, 6.5 m, coll. P. Hutchings & M. Capa, 28 Aug 2010, CReefs, gravid with coelomic gametes, 5.7 mm long, 1.6 mm wide anteriorly, 0.7 mm wide posteriorly. Paratypes: AM W.47429, MI QLD 2194 (2, 1 gravid with coelomic gametes), same locality as holotype, 3.1–4.5 mm long, 1.2–1.5 mm wide anteriorly, 0.8 mm wide posteriorly; AM W.47433, MI QLD 2194, same, 2.8 mm long, 1.2 mm wide anteriorly, 0.6 mm wide posteriorly, mounted for SEM.

Description. Preserved specimen pale cream in colour, small, conical in shape ( Fig. 1 A–B). Tube composed of cemented sand grains and shell fragments.

Rim of cephalic veil with 11 (10–13) long, narrow cirri, tips rounded and slightly expanded. Cephalic veil completely free from operculum forming dorsal semi-circle around the numerous buccal tentacles ( Fig. 2 A). Buccal tentacles conspicuous, markedly wide and deeply grooved, inverted V shaped ( Figs 1 A, 2A). Raised opercular margin well developed, divided into 15 (13–19) triangular lappets. Operculum with 14 (13–14) pairs of long paleae, yellow-gold, curved dorsally, thick at base and flatten towards distal end, tips extended ( Fig. 2 B), filiform when viewed under SEM ( Fig. 3 A). A stalked spherical structure was noted between the two sets of paleae, resembling a balloon ( Figs 2 B, 3A). Length of the structure approximately half of immediately neighbouring (shortest) paleae.

Tentacular cirri arise on anterior margin of segment 2. Segment 2 without anterodorsal lobe. Two pairs of comb-like branchiae on segments 3 and 4, situated laterally and consisting of loose flat lamellae ( Figs 2 C, 3B). Anterior pair situated more ventrally and almost twice as large as posterior pair.

Chaetigers 1 and 2 with broad anteroventral lobe, with that of chaetiger 1 more prominent. Anterior margin of lobes smooth. Nephridial papillae not observed.

Chaetigers 1–3 (segments 5–7) with notopodia and notochaetae only. Chaetigers 4–16 biramous with notopodia, neuropodia, notochaetae and neurochaetae ( Fig. 3 C). Chaetiger 17 with notopodia and notochaetae only. All notochaetae finely hirsute, some with smooth tip capillaries and some with broad distal pectinate wing ( Fig. 3 D). Neuropodia wedge-shaped, erect tori with numerous neurochaetae. Neurochaetal uncini with major teeth arranged in 3–6 longitudinal rows, each row with 6–9 teeth, with size of teeth declining basally ( Fig. 3 E).

Posterior 5 segments fused to form a flattened plate or scaphe, broader than long, or as broad as long ( Fig. 3 F). Scaphe with anal flap and dorsal papilla, scaphal margins crenulated and lobed ( Fig. 3 F–G). Small circular ciliated patches scattered across scaphal lobes, visible only under SEM ( Fig. 3 G). Scaphal hooks present, 4 pairs, broad, golden or yellow-brown, tips curved and pointed ( Figs 2 D, 3F).

Remarks. This new species Amphictene lizardensis n. sp. is characterized by 4 pairs of robust or broad based scaphal hooks with curved point tips and the arrangement of uncini teeth in 3–6 rows. Hutchings & Peart (2002) provided a summary of the diagnostic feature of all known species of Amphictene (see Table 1, Hutchings & Peart 2002) and a new species from the Gulf of Mexico has since been described (García-Garza & de León-González 2014). Amphictene lizardensis n. sp. most closely resembles A. auricoma ( O.F. Müller, 1776) described from Denmark in terms of number of cirri on cephalic veil and on the opercular rim. However, A. auricoma has significantly more scaphal hooks (8–18 pairs) than A. lizardensis n. sp. (4 pairs). The same character can be used to distinguish A. lizardensis n. sp. from the Australian species A. favona with 16 pairs of scaphal hooks. Amphictene uniloba , the other Australian species, has 4–10 pairs of scaphal hooks, but these are fine, in contrast to the broad based shape with curved pointed tips in A. lizardensis n. sp.

Etymology. The species is named after Lizard Island where the species was described from.

Habitat. Shallow subtidal sandy substrates.

Type locality. Queensland: Lizard Island, Watson’s Bay, 14°39'26"S, 145°27'3"E.

Distribution. Lizard Island, Queensland.

Figures

FIGURE 1. Amphictene lizardensis n. sp., stained with methyl green. A. Ventral view of entire animal, paratype, AM W. 47429; B. Dorsal view of entire animal, holotype, AM W. 47432. Scale bars: A – B = 0.1 mm.

FIGURE 2. Amphictene lizardensis n. sp., stained with methyl green, holotype, AM W. 47432. A. Ventral view of anterior end; B. Dorsal view of anterior end; C. Lateral view of anterior end; D. Dorsal view of posterior end. Abbreviations: br = branchiae, bt = buccal tentacles, cv = cephalic veil, or = opercular rim, p = paleae, s = scaphe, sh = scaphal hooks, ss = unknown spherical structure. Scale bars: A – D = 0.1 mm.

FIGURE 3. SEM images of Amphictene lizardensis n. sp., paratype, AM W. 47433. A. Antero-dorsal view, opercular rim with triangular lappets, characteristic of Amphictene species, paleae thick, distally curved and extended to form filiform tips; B. Ventral view of anterior end of specimen, buccal tentacles conspicuous and markedly wide, two pairs of branchiae inserted laterally on segments 3 and 4, consisting of loose flat lamellae, chaetae commence from segment 5; C. Ventro-lateral view of specimen, neuropodia with neurochaetae commencing from chaetiger 4; D. Notochaetae of chaetiger 4 finely hirsute, some with smooth tip capillaries and some with broad distal pectinate wings; E. Neurochaetae of thoracic chaetiger, uncini arranged in 3 – 6 longitudinal rows, each row with 6 – 9 teeth; F. Dorsal view of posterior end, scaphe as broad as long, scaphal hooks broad based with pointed tips, most pairs are lost in this specimen; G. Lateral view of posterior end, scaphal margin crenulated forming lobes. Abbreviations: br = branchiae, bt = buccal tentacles, cv = cephalic veil, nec = neurochaetae, noc = notochaetae, or = opercular rim, p = paleae, s = scaphe, sh = scaphal hook, ss = unknown spherical structure. Scale bars: A – C, F – G = 0.1 mm, B (insert), D – E = 0.01 mm.