Chaetozone lophia, Blake, 2022

Blake, James A., 2022, New species and records of Caulleriella, Chaetocirratulus and Chaetozone (Annelida, Cirratulidae) from continental shelf and slope depths of the Western North Atlantic Ocean, Zootaxa 5113 (1), pp. 1-89 : 71-76

Chaetozone lophia new species

Figures 37–38

urn:lsid:zoobank.org:act:32AC9EAE-E3F7-4CC5-84A4-48E556AC265A

Chaetozone sp. 10 : Blake et al. 1987: 61, 68, C-2; Maciolek et al. 1987b: D-2 (in part); Blake & Grassle 1994: 850, 855; Hilbig 1994: 940 (in part).

Chaetozone cf. setosa: Blake et al. 1987: 61 , 68, C-2; Blake & Grassle 1994: 850, 855; Hilbig 1994: 940 (in part). Not Malmgren, 1867.

Material examined. (184 specimens) US South Atlantic ACSAR Program , Off Cape Lookout, North Carolina, coll. J.A. Blake, Chief Scientist: Sta. 1: Cruise SA 1, Rep. 3, 11 Nov 1983, 34°16.00′N, 75°45.97′W, 580 m, holotype ( USNM 1661375 ) , 1 paratype ( USNM 1661376 ) ; Cruise SA 2, Rep. 1, 26 Mar 1984, 34°15.93′N, 75°46.16′W, 583 m, 2 paratypes ( USNM 1661377 ) ; Rep. 2, 26 Mar 1984, 34°15.81′N, 75°46.01′W, 583 m, 10 paratypes ( USNM 1661378 ) ; Rep. 3, 27 Mar 1984, 34°15.81′N, 75°45.78′W, 593 m, 11 paratypes ( USNM 1661379 ) ; Cruise SA 3, Rep. 1, 15 Jul 1984, 34°16.40′N, 75°45.80′W, 584 m, 4 paratypes ( USNM 1661380 ) ; Rep. 2, 15 Jul 1984, 34°16.30′N, 75°45.60′W, 599 m, 3 paratypes ( USNM 1661381 ) ; Rep. 3, 16 Jul 1984, 34°16.60′N, 75°45.60′W, 591 m, 2 paratypes ( USNM 1661382 ) .— Off Cape Fear , North Carolina. Sta. 11: Cruise SA 4, Rep. 2, 22 May 1985, 33°04.92′N, 76°24.97′W, 802 m, (1, USNM 1661383 ) ; Rep. 3, 22 May 1985, 33°04.87′N, 76°25.14′W, 799 m (2, USNM 1661384 ) ; Cruise SA 5, Rep. 1, 23 Sep 1985, 33°04.83′N, 76°25.19′W, 796 m (4, USNM 1661385 ) ; Rep. 2, 23 Sep 1985, 33°04.83′N, 76°25.17′W, 796 m (3, USNM 1661386 ) ; Cruise SA 6, Rep. 1, 22 Nov 1985, 33°04.95′N, 76°25.15′W, 804 m, (4, USNM 1661387 ) ; Rep. 2, 22 Nov 1985, 33°04.94′N, 76°25.17′W, 804 m (2 USNM 1661388 ) ; Rep. 3, 22 Nov 1985, 33°04.84′N, 76°25.06′W, 807 m (2, USNM 1661389 ) .— Off Charleston , South Carolina. Sta. 14: Cruise SA 4, Rep. 1, 20 May 1985, 32°23.64, 76°01.13′W, 805 m (6, USNM 1661390 ) ; Rep. 2, 20 May 1985, 32°23.64, 76°01.19′W, 802 m (5, USNM 1661391 ) ; Cruise SA 5, Rep. 2, 20 Sep. 1985, 32°23.72, 76°01.24′W, 799 (6, USNM 1661392 ) ; Rep. 3, 20 Sep. 1985, 32°23.63, 76°01.11′W, 799 m (4, USNM 1661393 ) ; Cruise SA 6, Rep. 1, 18 Nov 1985, 32°23.73, 76°01.10′W, 799 m (6, USNM 1661394 ) .— Off New England, U.S. North Atlantic ACSAR Program, coll. G.W. Hampson, Chief Scientist. Sta. 3: Cruise NA 5, Rep. 1, 27 Apr 1986, 41°01.46′N, 66°20.34′W, 1335 m (1, USNM 1661395 ) . Sta. 4: Cruise NA 1, Rep. 3, 09 Nov 1984, 41°01.39′N, 66°20.16′W, 1330 m (3, USNM 1661396 ) ; Cruise NA-2, Rep. 2, 22 Nov 1985, 41°01.42′N, 66°20.32′W, 1334 m (23, USNM 1661397 ) . Sta. 7: Cruise NA-1, Rep. 1, 10 Nov 1984, 40°27.54′N, 67°40.34′W, 560 m (2, USNM 1661409 ) . Sta. 9: Cruise NA 5, Rep. 1, 03 May 1986, 39°50.54′N, 70°01.79′W, 1214 m (1, USNM 1661408 ) . Sta. 12: Cruise NA-1, Rep. 2, 15 Nov. 1984, 39°54.35′N, 70°55.18′W, 558 m (4, USNM 1661398 ) ; Cruise NA-2, Rep. 1, 04 May 1985, 39°54.31′N, 70°55.04′W, 551 m (7, USNM 1661399 ) ; Rep. 2, 04 May 1985, 39°54.26′N, 70°55.07′W, 555 m (7, USNM 1661400 ) ; Cruise NA-4, Rep. 1, 30 Nov 1985, 39°54.28′N, 70°55.12′W, 560 m (8, USNM 1661401 ) ; Rep. 2, 30 Nov 1985, 39°54.28′N, 70°55.12′W, 559 (5, USNM 1661402 ) ; Rep. 3, 30 Nov 1985, 39°54.32′N, 70°55.12′W, 544 (9, USNM 1661403 ) ; Cruise NA-5, Rep. 1, 06 May 1986, 39°54.17′N, 70°55.22′W, 560 m (3, USNM 1661404 ) ; Rep. 3, 06 May 1986, 39°54.25′N, 70°55.09′W, 552 m (3, USNM 1661405 ) ; Cruise , NA-6, Rep. 2, 30 Jul 1986, 39°54.26′N, 70°55.07′W, 559 m (7, USNM 1661406 ) ; Rep. 3, 30 Jul 1986, 39°54.24′N, 70°55.09′W, 563 m (6, USNM 1661407 ) .

Description. Largest specimens generally range from 6–7 mm long with about 45–50 setigers. Holotype with 48 setigers, 7.0 mm long ( Figs. 37A–B , 38E–F ); large paratype (USNM 1661376) with 47 setigers, 6.7 mm long ( Fig. 38A–B ). Body elongate, generally cylindrical in cross section; anterior 12–15 setigers narrow, ca. 0.4 mm wide, then increasing in size with middle body segments often swollen and distended due to enlarged stomach area containing fine sediment particles ( Fig. 38A ), about 0.8 mm wide or wider; body then narrowing and tapering in posterior segments ( Fig. 38D ). Anterior and middle body segments short, about four times wider than long ( Fig. 37A–B ); posterior segments with deep cinctures and elevated membranes bearing armature of capillaries and acicular spines ( Figs. 37D , 38D ). Body terminates in narrow pygidium bearing rounded disk. Body with ventral ridge along most of length formed by medial bulge where segments meet mid-ventrally. Dorsal surface without ridges or grooves except in far posterior cinctured segments where notch sometimes present between the left and right notopodia ( Fig. 37D ). Color in alcohol light tan; larger specimens with black pigment spots on anterior and posterior lateral margins of first peristomial ring ( Fig. 37C ); these sometimes concentrated in discrete areas.

Pre-setiger region elongate, narrow, as long as first five setigers. Prostomium long, triangular, tapering to pointed tip ( Figs. 37A–C , 38A, C, E–F ); eyespots absent; nuchal organs rounded notches on posterior lateral margin ( Fig. 37C ). Peristomium long, divided into two distinct rings ( Figs. 37A–C , 38C ); first ring bulbous, with prominent dorsal crest extending onto second ring ( Fig. 37A ); second ring slightly narrower than first, not rounded, merging with setiger 1 ( Fig. 37A–C ); mouth a transverse opening on anterior border of first peristomial ring ( Fig. 37B ); dorsal tentacles arising from near posterior end of second ring ( Fig. 37A, C ); first pair of branchiae arising lateral and slightly posterior to dorsal tentacles ( Fig. 37A, C ). Second pair of branchiae arising dorsal and posterior to notosetae on setiger 1; subsequent branchiae in similar position ( Fig. 37A ); branchiae continuing to far posterior segments.

Parapodia of anterior and middle segments reduced to low ridges or mounds from which setae arise; posterior parapodia modified with deep intersegmental notches with parapodia becoming elevated and bearing thin membranes with acicular spines and capillaries ( Fig. 37D , 38D, G ). Anterior setae all long capillaries numbering about 12–15 per fascicle, including long natatory-like setae in notopodia of anterior and middle segments; these not associated with sexual maturity. Notopodial acicular spines from setigers 29–32 (holotype 30); neuropodial spines from setigers 25–27 (holotype 26). Spines numbering 1–3 initially, then increasing to 9–10 in notopodia and 7–8 in neuropodia; with 16–18 spines on a side ( Fig. 38G ). Spines alternating with capillaries only slightly longer and narrower than spines ( Fig. 38G–I ). Cinctures providing a prominent armature with narrow dorsal, lateral, and ventral gaps between noto- and neuropodial fascicles ( Figs. 38D, 38G ). Individual spines with basal manubrium at emergence from podial lobes; spines curving and tapering to narrow pointed tip ( Fig. 38G–I ).

Body terminating in short pygidium bearing a semicircular disk ventral to anal opening ( Figs. 37D , 38B, D ).

Methyl green staining. A distinct MG pattern produced on pre-setiger region and a few anterior setigers ( Fig. 38F ); most of body not retaining stain after differentiation. Prostomium stains from the tip to a curved clear area near the posterior margin; first peristomial ring stains entirely, separated from second ring by a curved clear area; second ring also staining. Anterior 2–3 setigers with notopodia retaining stain.

Remarks. Chaetozone lophia n. sp. is distinguished by having two peristomial rings, the first of which is enlarged and bulbous with a dorsal crest, the enlarged middle segments due to a stomach packed with sediment, and the distinctive MG staining pattern. In addition, most of the specimens have clusters of black pigment on the lateral sides of the first peristomial ring and sometimes on the venter posterior to the mouth.

Among species of Chaetozone with an enlarged and bulbous anterior ring on the peristomium, C. lophia n. sp. is similar morphologically in several respects to Chaetozone bathyala Blake, 2015 from the Canadian Arctic and Chaetozone grasslei Blake, 2019 from the abyssal Pacific Ocean. In C. bathyala , however, the second peristomial ring instead of being entire as in C. lophia n. sp., is distinctly divided into two parts, the second being a distinct achaetous segment anterior to setiger 1 that bears the first pair of branchiae. Chaetozone grasslei is a long slender threadlike species that lacks a dorsal crest and the enlarged middle segments and lacks the distinct MG staining pattern of C. lophia n. sp.

Biology. The collection included both juveniles and mature adults. One complete specimen (USNM 1661389) with 45 setigers has eggs protruding from six middle body segments (setigers 25–30). These eggs ranged from small, rounded oocytes of about 60 µm in diameter to larger, rounded eggs measuring up to 155 µm in longest diameter.

Etymology. The epithet is from the Greek, lophia for crest; in reference to the prominent dorsal crest on the peristomium of this species.

Distribution. Upper to middle continental slope: southeastern US, off the Carolinas, 580–807 m; northeastern US, off New England, 551–1335 m.

Figures

FIGURE 37. Chaetozone lophia n. sp. Holotype (USNM 1661375): A, anterior end, dorsal view; B, anterior end, ventral view. Paratype (USNM 1661380): C, anterior end, left lateral view; D, posterior end, dorsal view.

FIGURE 38. Chaetozone lophia n. sp. A, anterior end, left lateral view; B, posterior end with pygidial disk, dorsal view; C, anterior end, dorsal view; D, posterior end, dorsal view; E, anterior end, dorsal view; F, anterior end, dorsal view; G, posterior parapodium, anterior view; H, two notopodial acicular spines and a capillary from (G); I, neuropodial acicular spine and capillary from (G). A–E stained with Shirlastain A; F stained with MG. A–B, paratypes (USNM 1661377); C–D, holotype (USNM 1661375); E–F, paratypes (USNM 1661376); G–I, paratypes (USNM 1661380).