A revision of the genus Petta Malmgren, 1866 (Annelida: Pectinariidae), with two new species from deep waters of southeastern Australia, and comments on phylogeny of the family Author Zhang, Jinghuai Author Hutchings, Pat Author Kupriyanova, Elena text Zootaxa 2019 2019-06-10 4614 2 303 330 journal article 26539 10.11646/zootaxa.4614.2.3 d329726e-6a89-41a8-baba-b26dccac1751 1175-5326 3242403 3053533C-BDDE-4321-95B2-D557F3CF048D Petta investigatoris n. sp. Figs 9–11 , Table 2 Material examined: Holotype AM W.50672, Jervis Commonwealth Marine Reserve ( CMR ), Australia , 35º19.98´S 151º15.48´E , 2650– 2636 m , R/V “ Investigator ”, Voyage 3 St. 56, Beam trawl, May 2017 . Paratypes : AM W.50671, 1 specimen , Jervis CMR , Australia , 35º19.98´S 151º15.48´E , 2650– 2636 m , R/V “ Investigator ”, Voyage 3 St. 056, Beam Trawl, May 2017 ; AM W.50668, 1 specimen , Freycinet CMR , Australia , 36º21.042´S 150º54.858´E , 2793 m , R/V “ Investigator ”, Voyage 3 St. 11, biological box corer, May 2017 ; AM W.50670, 1 specimen , East Gippsland CMR , Australia , 37º47.52´S 150º22.92´E , 2338–2581 m , R/V “ Investigator ” Voyage 3 St. 035, Beam Trawl, May 2017 ; AM W.50669, 1 specimen , Bass Strait, Australia , 39º27.72´S 149º16.56´E , 2760– 2692 m , R/V “ Investigator ” Voyage 3 St. 22, Beam Trawl, May 2017 ; AM W.50666, 1 specimen , Freycinet CMR , Australia , 41º43.83´S 149º7.182´E , 2820– 2751 m , coll. R/V “ Investigator ” Voyage 3 St. 4, Beam Trawl, May 2017 . Description . Preserved specimens pale reddish in colour, cylindrical in shape ( Figs 9A ; 10 B–C). Body length of holotype 20.1 mm including paleae and scaphe, width 2.7 mm at cephalic regions. Cephalic veil heart-shaped, free from operculum, with narrow triangular anterior end and smooth margin ( Figs 9C ; 10D ). Pairs of lateral ear-shape lobes (palps) adjacent to dorsal base of cephalic veil ( Fig. 9F ). Buccal tentacles with broad longitudinal deep grooves, arising from around buccal cavity, posterior to cephalic veil ( Figs 9C ; 10D ). Lower lip not visible between buccal cavity and segment 1. Operculum semicircular; dorsal and lateral margins well developed, smooth; ventral margin (opercular ridge) with 13 pairs ( holotype ) of amber-coloured, stout long notopodial paleae, curved dorsally, with blunt tips ( Figs 9B ; 10E ). First pair of tentacular cirri not extending beyond tips of paleae, not distinctly annulated, arising from connection of opercular margin and paleal ridge ( Figs 9C ; 10D ). Pair of narrow triangular ventral lappets present behind tentacular cirri, on both sides of segment 1, partly covered by ventral lobes of segment 2 ( Figs 9C ; 10D ). Ventral region of segment 1 covered by ventral lobes of segment 2 ( Figs 9C ; 10D ). First and 2 nd pairs of tentacular cirri almost same length, annuli not distinct, 2 nd pair inserted more dorsally than 1 st pair , on almost mid-laterally connecting ridge of segment 2 ( Figs 9 A–B; 10D–E). Segment 2 with pair of broad ventro-lateral lobes, each with 7–8 triangular lappets, separated from each other by a narrow and deep mid-ventral groove ( Figs 9C ; 10D ). Two pairs of similar sized comb-like branchiae on segments 3–4, each consisting of large basal hump and series of loose, flat lamellae ( Figs 9G ; 10F ). First pair of branchiae on segment 3 inserted more ventrally than those on segment 4. Pair of dorso-lateral pads small and smooth, arising from dorsal side of notopodia on segment 5 ( Figs 9B ; 10E ). Distinct ventral glandular lobes (pads) present on segments 2–7, becoming progressively more dorsal and broader on segments 3–5 ( Figs 9A, C ; 10 D–E). Segment 3 with a pair of broad ventro-lateral lobes and a pair of short mid-ventral lappets, separated from those lobes by deep notches; ventro-lateral lobes with continuous row of papillae; mid-ventral lappets square rounded and narrow about 1/6 width of ventro-lateral lobes, and more posterior than ventro-lateral lobes ( Figs 9C ; 10D ). Segments 4–6 with a pair of broad ventro-lateral lobes separated from each other by a shallow median groove becoming progressively broader on segments 4–6. Segment 7 with a pair of ventro-lateral lobes separated from each other by a median swelling about 1/3 width of ventro-lateral lobes. Notopodia of segment 1 with paleae, segments 5–21 (17 pairs) with two rows of chaetae; anterior row of shorter chaetae with distal serrated wings, anterior surface from below wing to about mid-basal portion of chaeta covered with numerous minute spines; posterior row with about 1.5 times longer capillary chaetae, straight and stout, tapering to acute tips, anterior surface covered with numerous spines from mid-length to tip ( Figs 9 I–J; 11A–C). Neuropodia on segments 8–21 (14 pairs), each with slightly raised torus bearing a transverse row of uncini. Each uncinus with one rounded anterior peg with blunt tip embedded into torus, followed by several rows of minor teeth on a swelling, one longitudinal row of two major teeth, both covered by many small teeth basally ( Figs 9H ; 11 D–E). Neuropodia on segment 21 with elongated posterior lobe ( Figs 9A, E ; 10I ). Scaphe long ovoid, flattened dorsally, not distinctly separated by a constriction from posterior segments. Lateral margins dorsally rolled, with six pairs of lobes; first pair of lobes largest, connected to dorsal margin of scaphe; posterior lobes triangular, almost same size; dorsal margin of scaphe smooth with shallow median notch ( Figs 9 D–E; 10F–H). Anal flap vestigial with oblong swollen area distally bearing long anal cirrus ( Figs 9E ; 10F ). Anus located behind anal cirrus, between last pair of lateral lobes of scaphe. Nine pairs of scaphal hooks in the holotype , straight, amber-coloured, with blunt tips, on both sides of dorsal margin of scaphe ( Figs 9E ; 10I ). Tube slightly curved, made of coagulations and shells ( Fig. 10A ). FIGURE 9. Line drawings of Petta investigatoris n. sp. Holotype (AM W.50672): A. Lateral view of entire body; B. Dorsolateral view of anterior end; C. Ventral view of anterior end; D. Ventral view of posterior end; E. Dorso-lateral view of posterior end, showing lobes on lateral margin of scaphe; F. Lateral ear-shaped lobe adjacent to the dorsal base of cephalic veil, ventral view; G. Close-up view of branchia; H. Uncinus; I. Notochaeta from anterior row; J. Notochaeta from posterior row. Abbreviations: ac, anal cirrus; an, anus; ap, anterior peg; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorso-lateral pad; dms, dorsal margin of scaphe; hb, hump of branchia; lb, lamellae of branchia; lel, lateral ear-shaped lobe; mat, major teeth; mit, minor teeth; nec, neurochaetae; noc, notochaetae; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; tc, tentacular cirri; sh, scaphal hooks; vl, ventral lappet. FIGURE 10. Petta investigatoris n. sp. Methyl green stained body and tube of the holotype (AM W.50672): A. Tube; B. Ventral view of entire body; C. Dorso-lateral view of entire body; D. Ventral view of anterior end; E. Dorso-lateral view of anterior end; F. Close-up view of left branchiae, in lateral view; G. Dorsal view of posterior end; H. Ventral view of posterior end; I. Lateral view of posterior end, showing lobes on lateral margin of scaphe; J. Scaphal hooks. Abbreviations: ac, anal cirrus; an, anus; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dms, dorsal margin of scaphe; hb, hump of branchia; lb, lamellae of branchia; dlp, dorso-lateral pad; nec, neurochaetae; noc, notochaetae; nop, notopodium; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; tc, tentacular cirri; sh, scaphal hooks; vl, ventral lappet. FIGURE 11. Chaetae of Petta investigatoris n. sp. Holotype (AM W.50672) A–C. Close-up view of notochaetae, segment 12; B. Tip of notochaeta from posterior row; C. Tips of notochaetae from anterior row; D–E. Uncini, segment 12. Variability. The paratypes vary in length from 14.5 to 21.8 mm , including paleae and scaphe, width 2.3–3.1 mm at cephalic regions. Paleae 12–13 pairs. Scaphal hooks 9–12 pairs. Paratypes (AM W.50668 and AM W.50669) only with 3–4 papillae on ventro-lateral of segment 3. Some specimens with deep median notch on dorsal margin of scaphe. Distribution. Jervis CMR to Freycinet CMR along south-eastern coasts of Australia ( Fig. 1 ). Habitat. 2338–2820 m . No substrate data available. Etymology. The species is named “ investigatoris ” after the Australian Marine National Facility R/V “ Investigator ” because these specimens were collected during the 2017 “Sampling the Abyss” cruise on board this ship. Remarks . Petta investigatoris n. sp. can be distinguished from other species of Petta by the following characters: ventral lappets on segment 1 partly covered by ventral lobes of segment 2; short ventro-lateral lobes on segment 2 separated from each other by a narrow mid-ventral groove, and with 7–8 triangular lappets per lobe; ventrolateral lobes with continuous rows of papillae on segment 3; straight scaphal hooks ( Table 2 ). Petta investigatoris n. sp. is similar to P. assimilis as they both share continuous row of papillae on ventro-lateral lobes of segment 3. However, P. assimilis has a scale-like anal flap without anal cirrus and 4–5 lappets (fimbriae) on ventro-lateral lobes of segment 2, while P. investigatoris n. sp. has a vestigial anal flap with long anal cirrus and 7–8 lappets on the ventro-lateral lobes of segment 2.