Tharyx coloris, Blake, 2018

Blake, James A., 2018, Bitentaculate Cirratulidae (Annelida, Polychaeta) collected chiefly during cruises of the R / V Anton Bruun, USNS Eltanin, USCG Glacier, R / V Hero, RVIB Nathaniel B. Palmer, and R / V Polarstern from the Southern Ocean, Antarctica, and off Western South America, Zootaxa 4537 (1), pp. 1-130 : 101-104

publication ID

https://doi.org/ 10.11646/zootaxa.4537.1.1

publication LSID

lsid:zoobank.org:pub:169CBE5C-3A6E-438B-8A81-0491CBFBAC85

DOI

https://doi.org/10.5281/zenodo.3798472

persistent identifier

https://treatment.plazi.org/id/03A2CB16-FF91-A22D-FF36-FE2AFBC1FE30

treatment provided by

Plazi

scientific name

Tharyx coloris
status

sp. nov.

Tharyx coloris View in CoL new species

Figures 54–55 View FIGURE 54 View FIGURE 55

Chaetozone View in CoL sp. 1: Hilbig 2001: 540 (in part); Hilbig et al. 2006: 715, 717–719, 724 (in part).

Material examined. East Antarctic Peninsula, Prince Gustav Channel, RVIB Nathaniel B. Palmer Cr. 2000-3, coll. J.A. Blake , SM Grab, Sta. 01, 14 May 2000, 64°17.625ʹS, 058°34.678ʹW, 768 m, holotype ( LACM-AHF Poly 10225) and 50 paratypes ( LACM-AHF Poly 10226); Sta. 27, 23 May 2000, 64°22.934ʹS, 58°36.976ʹW, 684 m, 11 paratypes ( LACM-AHF Poly 10227); Sta. 28, 23 May 2000, 64°22.018ʹS, 058°30.942ʹW, 794 m, 37 paratypes ( LACM-AHF Poly 10228); Sta. 29, 24 May 2000, 64°21.361ʹS, 058°26.637ʹW, 690 m, 29 paratypes ( USNM 1490746 View Materials ); Sta. 30, 24 May 2000, 64°16.875ʹS, 058°26.985ʹW, 843 m, 8 paratypes ( USNM 1490747 View Materials ); Sta. 33, 24 May 2000, 64°11.959ʹS, 058°41.857ʹW, 587 m, 11 paratypes ( USNM 1490748 View Materials ); Sta. 34, 24 May 2000, 64°10.995ʹS, 058°34.140ʹW, 865 m, 15 paratypes ( MCZ 149854 View Materials ); Sta. 35, 25 May 2000, 64°10.471ʹS, 058°28.505ʹW, 651 m, 14 paratypes GoogleMaps ( MCZ 149855 View Materials .— East Antarctic Peninsula , Former Larsen Ice Shelf A area, Greenpeace Trough , RVIB Nathaniel B. Palmer Cr. 2000-3, coll. J.A. Blake , SM grab, Sta. 7B, 18 May 2000, 64°43.523ʹS, 060°04.771ʹW, 839 m (1, JAB); border with Larsen B GoogleMaps , RVIB Nathaniel B. Palmer Cr. 2000-3, coll. J.A. Blake , SM grab, Sta. 12, 19 May 2000, 64°55.101ʹS, 060°24.459ʹW, 317 m (2, JAB); Sta. 13, 19 May 2000, 64°53.517ʹS, 060°28.836ʹW, 323 m (3, JAB); Sta. 14, 19 May 2000, 64°51.818ʹS, 060°33.438ʹW, 419 m (3, JAB); Greenpeace Trough, Sta. 18, 20 May 2000, 64°39.381ʹS, 059°59.498ʹW, 665 m (1, JAB).— Weddell Sea, east of former Larsen Ice Shelf A area GoogleMaps , RVIB Nathaniel B. Palmer Cr. 2000-3, coll. J.A. Blake , SM grab, Sta. 26, 23 May 2000, 64°39.564ʹS, 059°13.226ʹW, 564 m (26, MCZ 149856 View Materials ); Weddell Sea, SW of Vestkapp GoogleMaps , EASIZ II, R / V Polarstern, ANT-XV/3, coll. B. Hilbig, Sta. MG 48-093 , 4 Feb 1998, 73°28.3ʹS, 22°54.5ʹW, 1988 m, 994 m, (4, SMF 24937); Weddell Sea, off Coats Land GoogleMaps , USCG Glacier, Sta. 69-8, 02 Mar 1969, 77°36.2ʹS, 42°30ʹW, 585 m (1, USNM 1490749 View Materials ) GoogleMaps .

Description. A moderately sized species, holotype complete, 9.3 mm long, 0.65 mm wide across gravid middle body segments, with 85 setigerous segments. Largest paratypes similar, 9–9.5 mm long with 75–90 segments. Body elongate, generally widest in gravid middle body segments, narrowing in far posterior segments. Anterior segments narrow, about ten times wider than long ( Fig. 54A View FIGURE 54 ); posterior segments narrower, about three times wider than long ( Fig. 54C View FIGURE 54 ); moniliform or oblong segments absent. Dorsal groove or ridge absent, dorsum broad, relatively smooth anteriorly; with shallow ventral groove present from anterior segments to near posterior end ( Fig. 55C View FIGURE 55 ); this groove typically with a mid-ventral bulge in each segment where two sides join resulting in low ridge. Color in alcohol overall light tan, but with distinctive brownish-red pigment scattered over peristomium, anterior parapodia, and branchial stubs ( Fig. 55B View FIGURE 55 ); ventrally pigment on each segment follows contours across mid-ventral groove and central ridge ( Fig. 55C View FIGURE 55 ). This pigment very dark and intense on some specimens, faded in others; highly diagnostic for this species.

Prostomium broad, triangular, narrowing to rounded tip ( Figs. 54 View FIGURE 54 A–B, 55B–D); eyespots absent; nuchal organs shallow grooves on posterior lateral margin of prostomium ( Figs. 54B View FIGURE 54 , 55D View FIGURE 55 ). Peristomium broad, wider than long, with three annular rings, best seen dorsally ( Fig. 54 View FIGURE 54 A–B); middle ring largest, dorsally expanded, extending anteriorly over first ring and posteriorly over third ring, forming rounded dorsal crest ( Fig. 54 View FIGURE 54 A–B). Third ring narrow, similar in shape to setiger 1 and may be an achaetous segment; dorsal tentacles and first pair of branchiae arising on third ring with branchiae located lateral and slightly posterior to tentacles ( Fig. 54 View FIGURE 54 A–B). Second pair of branchiae on setiger 1 dorsal to notosetae ( Fig. 54 View FIGURE 54 A–B); branchiae of following segments in similar location; branchiae observed on segments in middle body segments but not in posterior segments.

Parapodia reduced to simple setal tori; postsetal lamellae absent. Setal fascicles of noto- and neuropodia close together throughout body. Notosetae long capillaries including long natatory-like setae throughout most of body, absent in smaller specimens; notosetae of anterior segments 6–10 per fascicle, reduced to 3–5 posteriorly; notoacicular spines entirely absent. Neuroacicular spines relatively simple, first present from about setiger 60 or later; individual spines geniculate to sickle-shaped, tapering to narrow sub-bidentate or knobbed tip ( Fig. 54 View FIGURE 54 D–F), detail of tips difficult to observe in some views, with some appearing to have angled tips ( Fig. 55E View FIGURE 55 ); some posterior fascicles with up to 5–6 spines per neuropodium with some having geniculate shaft with capillary tips ( Fig. 54G View FIGURE 54 ) and transitioning to blunt-tipped spines ( Fig. 54 View FIGURE 54 D–F); spines curved toward notopodia.

Last few segments narrowing to short pygidium bearing single rounded lobe ventral to anal opening ( Fig. 54C View FIGURE 54 ).

Methyl Green stain. No distinct staining pattern anywhere along body; stain retained only in intersegmental furrows.

Etymology. Coloris is Latin for hue or tint, referring to the reddish colored pigment prominent on the anterior body segments of this species.

Remarks. Tharyx coloris n. sp. is superficially similar to Chaetozone homosetosa with which it may co-occur. A careful comparison of pigment, Methyl Green staining reactions, and the morphology of both soft and hard body parts confirmed that two different species were present. Tharyx coloris n. sp. differs from other species of Tharyx globally by having distinctive reddish-brown pigment over much of the body and from Antarctic species by the entire absence of notoacicular spines.

Habitat & biology. Specimens from the East Antarctic Peninsula were collected in May 2000. Mature females were present with numerous eggs in individual parapodia from about setiger 15 and continuing to about 20 setigers from the pygidium. The largest eggs ranged from 170–180 µm in the longest dimension.

Tharyx coloris n. sp. is one of several bitentaculate cirratulids common in the vicinity of the Prince Gustav Channel and the former Larsen Ice Shelf A collected in May 2000. The surficial sediments at these locations consisted of 20–40% sand in the upper 0–5 cm ( Gilbert & Domack 2003).

Distribution. East Antarctic Peninsula, 317–794 m; Weddell Sea, 564–1988 m.

SM

Sarawak Museum

R

Departamento de Geologia, Universidad de Chile

V

Royal British Columbia Museum - Herbarium

SMF

Forschungsinstitut und Natur-Museum Senckenberg

USCG

Universidad de San Carlos de Guatemala

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Terebellida

Family

Cirratulidae

Genus

Tharyx

Loc

Tharyx coloris

Blake, James A. 2018
2018
Loc

Chaetozone

Hilbig, B. & Gerdes, D. & Montiel, A. 2006: 715
Hilbig, B. 2001: 540
2001
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