Amphictene uniloba Hutchings & Peart, 2002

Zhang, Jinghuai & Hutchings, Pat, 2019, A revision of Australian Pectinariidae (Polychaeta), with new species and new records, Zootaxa 4611 (1), pp. 1-70 : 16-19

Amphictene uniloba Hutchings & Peart, 2002

Figs 8–9 , Table 1

Amphictene uniloba Hutchings & Peart, 2002: 99 – 127 , figs 4 – 5 & 6 – 8.

Material examined. Australia, New South Wales: AM W.25612 (Holotype) , AM W.25613 (Paratypes), 3 specs, Jibbon Beach, near Cronulla, 34°03’S 151°09’E, 100 m, coll. R.J. MacIntyre, 05 Dec 1965 .

Additional material examined. Australia, New South Wales: AM G.11197, 1 spec., Port Stephens , 32°42’S 152°06’E, Sep 1908 ; AM W.24196, 2 specs (1 spec. mounted for SEM), off Cronulla , 34°04’S 151°14’E, 80 m, coll. R.J. MacIntyre, 12 Aug 1964 .

Description. Based on all material examined. Preserved specimens pale reddish in colour, conical in shape ( Fig. 8A, B ). Body length 20.0 – 35.0 mm (holotype 33.0 mm) including paleae and scaphe, width 4.2 – 6.0 mm (holotype 4.5 mm) at cephalic regions.

Cephalic veil oval, free from operculum, with 26 – 32 (holotype 26) smooth cirri on anterior and 2/3 of lateral margins ( Figs 8A ; 9A ). Pair of ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil. Buccal tentacles with wide longitudinal grooves, arising posterior to cephalic veil ( Figs 8A ; 9A ).

Operculum semicircular; dorsal and lateral margin well developed, with 26 – 32 (holotype 29) triangular lappets; ventral margin (opercular ridge) with 11 – 13 (holotype with 12 left, 13 right) pairs of golden paleae, curved dorsally, acute with extended tips ( Figs 8A – C ; 9A – B ).

First pair of tentacular cirri extending to tips of paleae, with annuli, arising from connection of opercular margin and paleal ridge ( Figs 8B – C ; 9A – B ). Pair of small ventral lappets present ventrally to tentacular cirri, near cephalic veil on segment 1. Ventral region of segment 1 covered by buccal tentacles and ventral lobes of segment 2 ( Figs 8A ; 9A ).

Second pair of tentacular cirri extending beyond opercular margin, with annuli, on latero-median connecting ridge on segment 2, inserted more dorsally than 1 st pair of tentacular cirri ( Figs 8C ; 9B ). Segment 2 with ventral lobes as pair of broad ventro-lateral lobes separated by shallow grooves from base of 2 nd pair of tentacular cirri, and narrow mid-ventral lobe about 1/4 width of ventro-lateral lobes ( Figs 8A ; 9A ). Dorsal lobe absent on segment 2 ( Figs 8C ; 9B ).

Comb-like branchiae on segments 3 – 4, consisting of series of dense, flat lamellae ( Figs 8B – C ; 9A – B ). Branchiae on segment 3 larger and inserted more ventrally than those of segment 4. Pair of small dorso-lateral glandular pads present adjacent to branchiae on segments 3 and 4 ( Figs 8B – C ; 9B ).

Distinct ventral glandular lobes present on segments 3 – 6, becoming progressively more lateral and broader on segments 3 – 5 ( Figs 8A – B ; 9A – B ). Hump near branchiae obscure on segment 4. Segment 3 with broad ventral lobe, higher at mid-line ( Figs 8A ; 9A ). Segment 4 with pair of broad ventro-lateral lobes and narrow mid-ventral lobe about 1/2 width of ventro-lateral lobes, separated from those by shallow grooves. Segment 5 with pair of broad ventro-lateral lobes and narrow mid-ventral lobe about 1/2 width of ventro-lateral lobes, separated from those by shallow grooves. Segment 6 with pair of broad ventro-lateral lobes and pair of narrow mid-ventral lobes about 1/4 width of ventro-lateral lobes, separated from those by shallow grooves. Segment 7 with pair of ventro-lateral lobes interrupted mid-ventrally ( Figs 8A ; 9A ).

Notopodia other than those of segment 1 which bear paleae, on segments 5 – 21 (17 pairs), each bearing two kinds of notochaetae; one winged, bordered with serrations along distal portion, covered progressively with more spines from about middle to front of wing, on anterior surface; other stout, straight, tapering to an acute tip, covered progressively with more spines from mid-anterior portion to end, on anterior surface ( Fig. 9F ). Neuropodia, 13 pairs on segments 8 – 20, each with slightly raised torus with transverse row of uncini; each uncinus with U-shaped anterior peg embedded into torus, several rows of minor teeth, one large tooth and 2 – 4 longitudinal rows of major teeth, with number of teeth per row decreasing from centre to side, up to eight teeth per row ( Fig. 9G ). Segment 21 with pair of ventro-lateral lobes near notopodia ( Figs 8A – B ; 9C ).

Scaphe long ovoidal, flattened dorsally, divided into three anterior narrow lobes, two medial, broad triangular or rounded lobes, plus small rounded lobe on each lateral margin; distal margin with contiguous rounded lappets near anal flap ( Figs 8D – E ; 9C – E ). Anal flap long triangular with smooth margin and short cirrus dorsally ( Figs 8D – E ; 9D – E ). Scaphal hooks 5 – 7 (holotype 6) pairs, amber, tip pointed and strongly curved ( Fig. 9H ).

Tube conical with wide opening, slightly curved, fragile wall made of sand grains and shells ( Fig. 8F ).

Methyl Green stained body distinctly green on ventral lobes of segments 2–6, base of 2 nd pair of tentacular cirri, and dorso-lateral pads of segments 3–4 ( Fig. 8 A–C).

Distribution. New South Wales ( Fig. 1 ).

Habitat. Found in 80– 100 m.

Remarks. We have expanded the original description of Amphictene uniloba Hutchings & Peart, 2002 , providing additional images of the holotype and described some additional structures including the presence of a pair of lateral ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil, pair of small ventral lappets on segment 1, provided details of ventral lobes on segments 3–6, and additional details re the structure of the uncini and the scaphal lateral lobes. Amphictene uniloba can be distinguished from all other described species of Amphictene by the following combination of characters: opercular dorsal and lateral margin with triangular lappets without cirri; posterior margin of scaphe with contiguous rounded lappets near anal flap; 5 – 7 pairs of small scaphal hooks with strongly curved tips and uncini with 1 – 6 longitudinal rows of major teeth, and with a large tooth in the middle of the uncini (Table 1). The species can be easily distinguished from the other Australian species of Amphictene : A. favona which has a dorsal lobe on segment 2 and more pairs of scaphal hooks which are straight; and A. lizardensis which has numerous cirri on the lateral and dorsal opercular margins and 3 – 6 longitudinal rows of major uncinial teeth.

Figures

FIGURE 1. Distribution of the species of Amphictene, Lagis and Pectinaria in Australia.

FIGURE 8. Amphictene uniloba Hutchings & Peart, 2002 Methyl Green stained body and tube of Holotype (AM W.25612): A. Ventral view of entire body; B. Lateral view of entire body; C. Lateral view of anterior end; D. Dorsal view of posterior end; E. Lateral view of posterior end; F. Tube. Abbreviations: ac, anal cirrus; af, anal flap; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorso-lateral pads; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; sh, scaphal hooks; tc, tentacular cirri.

FIGURE 9. Amphictene uniloba Hutchings & Peart, 2002 SEM (AM W.24196): A. Ventral view of anterior end; B. Lateral view of anterior end; C–D. Lateral and dorsal view of posterior end; E. Close up of anal flap; F. Notochaetae, segment 10; G. Uncini, segment 10; H. Scaphal hooks. Abbreviations: ac, anal cirrus; af, anal flap; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorso-lateral pads; nec, neurochaetae; noc, notochaetae; or, opercular rim; p, paleae; s, segment; sc, scaphe; sh, scaphal hooks; tc, tentacular cirri.