Ampharete undecima, Alvestad, 2014

Alvestad, Tom, 2014, Ampharete undecima, a new deep-sea ampharetid (Annelida, Polychaeta) from the Norwegian Sea, Memoirs of Museum Victoria 71, pp. 11-19 : 12-15

Ampharete undecima sp. nov.

Zoobank LSID. http://zoobank.org/ urn:lsid:zoobank.org:act:

405975B9-C3FF-4CEE-92FF-44C0A3671AAD

Figures 2–6

Type locality. Norwegian Sea, 72.367ºN 14.895ºE, 770 m depth.

Type material. RV G.O. Sars MAREANO stn R379-47 , RP, 9 Apr 2009, holotype ( ZMBN 94022 ), 2 paratypes mounted for SEM ( ZMBN 94023 ), 19 paratypes ( ZMBN 94024 ), 19 paratypes ( ZMBN 94025 ) and 1 paratype ( ZMBN 94026 ) .

Additional material. RV H. Mosby: Stn 81.03.21.1, 63.166ºN 4.816ºE, 830 m, 21 Mar 1981 (1 spec.); stn 81.06.04.4, 66.983ºN 4.270ºE, 1380 m, 4 Jun 1981 (1) ; stn 81.06.06.7, 65.716ºN 5.238ºE, 794 m, 6 Jun 1981 (34); stn 81.06.06.8, 65.666ºN 4.815ºE, 996 m, 6 Jun 1981 (9); stn 81.08.16.3, 62.800ºN 1.043ºE, 1009 m, 16 Aug 1981 (3); stn 82.01.21.2, 62.491ºN 1.721ºE, 604 m, 21 Jan 1982 (6); stn 82.01.21.4, 62.560ºN 0.981ºE, 804 m, 21 Jan 1982 (5); stn 82.01.21.6, 62.803ºN 1.088ºE, 984 m, 21 Jan 1982 (5); stn 82.08.15.1, 63.048ºN 0.808ºE, 1286 m, 15 Aug 1982 (2); stn 82.08.23.1, 63.213ºN 3.121ºE, 1003 m, 23 Aug 1982 (3); stn 82.11.26.1, 63.178ºN 2.765ºE, 1030 m, 26 Nov 1982 (1); stn 82.11.27.1, 62.985ºN 3.218ºE, 804 m, 27 Nov 1982 (73); stn 83.06.02.1, 62.198ºN 0.003ºW, 708 m, 2 Jun 1983 (15); stn 83.06.03.2, 60.201ºN 6.625ºW, 1220 m, 3 Jun 1983 (55); stn 83.06.08.1, 65.168ºN 9.493ºW, 784 m, 8 Jun 1983 (4); stn 83.06.08.2, 65.460ºN 7.588ºW, 1626 m, 8 Jun 1983 (3); stn 83.06.17.2, 62.338ºN 1.411ºW, 543 m, 17 Jun 1983 (1); stn 83.06.17.3, 62.593ºN 1.233ºW, 781 m, 17 Jun 1983 (18); stn 84.05.23.1, 62.585ºN 1.793ºW, 656 m, 23 May1984 (328); stn 84.05.23.3, 62.508ºN 1.851ºW, 576 m, 23 May 1984 (5); stn 84.05.23.7, 62.411ºN 1.540ºW, 575 m, 23 May 1984 (2); stn 84.11.20.2, 63.133ºN 1.895ºW, 1087 m, 20 Nov 1984 (29); stn 84.11.21.1, 62.791ºN 1.836ºW, 811 m, 21 Nov 1984 (2); stn 85.01.08.1, 62.525ºN 1.443ºW, 701 m, 08 Jan 1985 (135); stn 85.01.08.2, 62.706ºN 1.186ºW, 897 m, 08 Jan 1985 (44); stn 85.01.12.2, 63.166ºN 0.643ºW, 1489 m, 12 Jan 1985 (1); stn 85.01.12.3, 63.048ºN 0.796ºW, 1293 m, 12 Jan 1985 (1); stn 86.06.13.1, 63.218ºN 7.031ºW, 1261 m, 13 Jun 1986 (1); stn 86.07.25.1, 69.023ºN 8.410ºW, 879 m, 25 Jul 1986 (10); stn 86.07.27.2, 70.810ºN 9.728ºW, 886 m, 27 Jul 1986 (6); stn 86.08.15.5, 62.610ºN 1.573ºW, 654 m, 15 Aug 1986 (26); stn 86.08.15.7, 62.843ºN 1.431ºW, 951 m, 15 Aug 1986 (15); stn 86.08.17.5, 62.996ºN 1.140ºW, 1143 m, 17 Aug 1986 (4); stn 86.08.17.6, 62.691ºN 1.756ºW, 750 m, 17.08.1986 (115). RV Meteor: Stn M 410/90, 74.843ºN 15.377ºW, 894 m, 16 Jul 1990 (79) ; stn M507/90, 74.883ºN 15.275ºW, 991 m, 28 Jul 1990 (87). RV G.O. Sars MAREANO: Stn R209-17 , GR, 69.800ºN 16.420ºW, 1590 m, 5 Jun 2008 (1) ; stn R209-18 , GR, 69.800ºN 16.420ºW, 1590 m, 5 Jun 2008 (1) ; stn R229-27 , GR, 69.142ºN 13.682ºW, 1115 m, 11 Jun 2008 (1) ; stn R232-34 , GR, 69.407ºN 14.696ºW, 1408 m, 14 Jun 2008 (1) ; stn R297-346 , GR, 68.653ºN 11.908ºW, 807 m, 14 Oct 2008 (3) ; stn R297-347 , GR, 68.653ºN 11.908ºW, 807 m, 14 Oct 2008 (1) ; stn R351-355 , GR, 68.840ºN 13.087ºW, 765 m, 29 Oct 2008 (2) ; stn R351-356 , GR, 68.840ºN 13.087ºW, 765 m, 29 Oct 2008 (2) ; stn R379-363 , GR, 72.367ºN 14.895ºW, 760 m, 9 Apr 2009 (5) ; stn R379-47 , RP, 72.367ºN 14.895ºW, 770 m, 9 Apr 2009 (10) ; stn R391-370 , GR, 72.278ºN 15.666ºW, 729 m, 12 Apr 2009 (5) ; stn R391-51 , RP, 72.281ºN 15.666ºW, 728 m, 12 Apr 2009 (34) ; stn R397-54 , RP, 72.247ºN 15.945ºW, 635 m, 14 Apr 2009 (3) ; stn R404-381 , GR, 72.078ºN 15.806ºW, 621 m, 15 Apr 2009 (1) ; stn R405-59 , RP, 72.140ºN 15.346ºW, 899 m, 20 Apr 2009 (20) ; stn R406-61 , RP, 72.189ºN 14.829ºW, 1030 m, 21 Apr 2009 (20) ; stn R444-148 , RP, 71.741ºN 15.236ºW, 993 m, 20 Sep 2009 (7) ; stn R776-51 , BC, 68.189ºN 10.362ºW, 873 m, 3 May 2012 (1) . Environmental monitoring: Stn V-12, 67.002ºN 5.334ºW, 1330 m, 1 Jun 1998 (2).

Diagnosis. A small species of up to 5 mm in length and 0.5 mm in width. Branchiae arranged close together; three pairs in anterior transverse row and last pair in a posterior position. Paleae long, thin and slender with curved tips, 9–12 on each side. Abdomen with 11 chaetigerous segments. Pygidium with two short conical lateral cirri and a number of small rounded papillae.

Description. Holotype, complete, 4 mm long and 0.4 mm wide in thorax (fig. 2A–B). Other complete specimens are up to 5 mm in length and 0.5 mm in width. Colour in alcohol pale yellow.

Prostomium trilobed, without glandular ridges or eyes; prostomial median lobe delimited by deep lateral grooves, widest at the base, gradually narrowing to form acute, rounded frontal part (fig. 3A–B). Paired nuchal organs as circular, ciliated spots located in lateral grooves at base of median prostomial lobe (fig. 3B). Buccal tentacles with secondary filaments, pinnae; tips of pinnae covered by tufts of cilia (fig. 4B–C). Four pairs of long branchiae on fused segment II+III; three pairs of branchiae arranged in anterior, transverse row without median gap, fourth pair slightly posterior to anterior row, between 2nd outermost and innermost branchiae of anterior row (fig. 2C). Bases of branchiae in anterior row completely fused, forming a characteristic and well-marked edge above head in frontal view (fig. 3A–B). Branchiae of segment II in 2nd outermost position of anterior row, branchiae of segment III in outermost position of anterior row, branchiae of segment IV in innermost position of anterior row, branchiae of segment V in posterior position (figs 2C, 4A). One pair of nephridial papillae, located dorsally between the two posterior branchiae on segment IV (figs 2C, 4A). Fused segment II and III with 9–12 long, thin and slender paleae on each side, with curved tips (figs 3B, D, 5A). Thorax and abdomen of similar length; thorax slightly wider than abdomen, slightly tapering posteriorly (figs 2A, 3C). Abdomen of similar width throughout, or slightly tapering posteriorly. A total of 14 thoracic segments with notopodia and capillary chaetae. Last 12 chaetigers of thorax with neuropodia and uncini (figs 2A, 3A, C). Notopodia simple, finger-shaped; first 2 reduced, remaining 12 up to 3 times longer than wide. Notochaetae as spinulose capillaries (fig. 5F–G), arranged in double rows; capillaries from anterior row generally thinner and shorter than from posterior row. Thoracic neuropodia rounded to oval (fig. 3C). Thoracic uncini with two vertical rows of 4–6 teeth above rostrum (fig. 5B–C). Continuous ventral shields present to thoracic unciniger 8. A total of 11 abdominal uncinigers (fig. 2A–B, 3C). Anterior 2 abdominal segments with neuropodia as thoracic type (fig. 3C); remaining abdominal uncinigers with enlarged neuropodia without cirri (figs 3A, C, 5D). Abdominal uncini with 4 vertical rows of 4–6 teeth above rostrum (fig. 5D–E). Pygidium with terminal ciliated anal opening, surrounded by 2 short lateral cirri and small rounded papillae (figs 2B, 4D). Head and ventral shields dyed by methyl blue; anterior tip of prostomium with particularly strong colour (fig. 6A–C). Tube unknown.

Distribution. Common and widespread in the Nordic Seas in depths ranging from 600–1650 m (fig. 1).

Etymology. The species is named after the Latin word for eleven, referring to the eleven abdominal segments.

Remarks. Ampharete undecima sp. nov. is referred to the genus Ampharete based on the presence of a trilobed prostomium without glandular ridges, and with the median lobe delimited by deep grooves, buccal tentacles with pinnulae, the presence of four pairs of branchiae arising from the fused segment II+III, 12 thoracic uncinigers, and a single pair of nephridial papillae located dorsally on segment IV ( Parapar et al., 2012; Imajima et al., 2012).

Ampharete undecima sp. nov. differs from all known species of Ampharete in having 11 rather than 12–28 abdominal uncinigerous segments. In the Norwegian Sea, A. undecima sp. nov. commonly occurs together with two other species of the genus, A. cf. lindstroemi (Malmgren, 1867) and A. finmarcicha (M. Sars, 1865) (Alvestad and Kongsrud, pers. obs.). A. undecima sp. nov. may easily be distinguished from both by a number of characters in addition to the number of abdominal uncinigers, including body size, the narrow and tapering middle lobe of the prostomium, number and shape of paleae, and arrangement of the branchiae ( Holthe, 1986; Parapar et al., 2012; pers. obs.).