Tharyx coloris Blake 2018
- Dataset
- 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
- Rank
- SPECIES
- Published in
- 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): 1-130, DOI: 10.11646/zootaxa.4537.1.1
Classification
- kingdom
- Animalia
- phylum
- Annelida
- class
- Polychaeta
- order
- Terebellida
- family
- Cirratulidae
- genus
- Tharyx
- species
- Tharyx coloris
description
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. 54 A); posterior segments narrower, about three times wider than long (Fig. 54 C); 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. 55 C); 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. 55 B); ventrally pigment on each segment follows contours across mid-ventral groove and central ridge (Fig. 55 C). 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 A – B, 55 B – D); eyespots absent; nuchal organs shallow grooves on posterior lateral margin of prostomium (Figs. 54 B, 55 D). Peristomium broad, wider than long, with three annular rings, best seen dorsally (Fig. 54 A – B); middle ring largest, dorsally expanded, extending anteriorly over first ring and posteriorly over third ring, forming rounded dorsal crest (Fig. 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 A – B). Second pair of branchiae on setiger 1 dorsal to notosetae (Fig. 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 D – F), detail of tips difficult to observe in some views, with some appearing to have angled tips (Fig. 55 E); some posterior fascicles with up to 5 – 6 spines per neuropodium with some having geniculate shaft with capillary tips (Fig. 54 G) and transitioning to blunt-tipped spines (Fig. 54 D – F); spines curved toward notopodia. Last few segments narrowing to short pygidium bearing single rounded lobe ventral to anal opening (Fig. 54 C). Methyl Green stain. No distinct staining pattern anywhere along body; stain retained only in intersegmental furrows.
description
Figures 54 – 55
discussion
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
Distribution. East Antarctic Peninsula, 317 – 794 m; Weddell Sea, 564 – 1988 m.
etymology
Etymology. Coloris is Latin for hue or tint, referring to the reddish colored pigment prominent on the anterior body segments of this species.
materials_examined
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 ° 17.625 ʹS, 058 ° 34.678 ʹW, 768 m, holotype (LACM-AHF Poly 10225) and 50 paratypes (LACM-AHF Poly 10226); Sta. 27, 23 May 2000, 64 ° 22.934 ʹS, 58 ° 36.976 ʹW, 684 m, 11 paratypes (LACM-AHF Poly 10227); Sta. 28, 23 May 2000, 64 ° 22.018 ʹS, 058 ° 30.942 ʹW, 794 m, 37 paratypes (LACM-AHF Poly 10228); Sta. 29, 24 May 2000, 64 ° 21.361 ʹS, 058 ° 26.637 ʹW, 690 m, 29 paratypes (USNM 1490746); Sta. 30, 24 May 2000, 64 ° 16.875 ʹS, 058 ° 26.985 ʹW, 843 m, 8 paratypes (USNM 1490747); Sta. 33, 24 May 2000, 64 ° 11.959 ʹS, 058 ° 41.857 ʹW, 587 m, 11 paratypes (USNM 1490748); Sta. 34, 24 May 2000, 64 ° 10.995 ʹS, 058 ° 34.140 ʹW, 865 m, 15 paratypes (MCZ 149854); Sta. 35, 25 May 2000, 64 ° 10.471 ʹS, 058 ° 28.505 ʹW, 651 m, 14 paratypes (MCZ 149855. — 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. 7 B, 18 May 2000, 64 ° 43.523 ʹS, 060 ° 04.771 ʹW, 839 m (1, JAB); border with Larsen B, RVIB Nathaniel B. Palmer Cr. 2000 - 3, coll. J. A. Blake, SM grab, Sta. 12, 19 May 2000, 64 ° 55.101 ʹS, 060 ° 24.459 ʹW, 317 m (2, JAB); Sta. 13, 19 May 2000, 64 ° 53.517 ʹS, 060 ° 28.836 ʹW, 323 m (3, JAB); Sta. 14, 19 May 2000, 64 ° 51.818 ʹS, 060 ° 33.438 ʹW, 419 m (3, JAB); Greenpeace Trough, Sta. 18, 20 May 2000, 64 ° 39.381 ʹS, 059 ° 59.498 ʹW, 665 m (1, JAB). — Weddell Sea, east of former Larsen Ice Shelf A area, RVIB Nathaniel B. Palmer Cr. 2000 - 3, coll. J. A. Blake, SM grab, Sta. 26, 23 May 2000, 64 ° 39.564 ʹS, 059 ° 13.226 ʹW, 564 m (26, MCZ 149856); Weddell Sea, SW of Vestkapp, EASIZ II, R / V Polarstern, ANT-XV / 3, coll. B. Hilbig, Sta. MG 48 - 093, 4 Feb 1998, 73 ° 28.3 ʹS, 22 ° 54.5 ʹW, 1988 m, 994 m, (4, SMF 24937); Weddell Sea, off Coats Land, USCG Glacier, Sta. 69 - 8, 02 Mar 1969, 77 ° 36.2 ʹS, 42 ° 30 ʹW, 585 m (1, USNM 1490749).
Name
- Homonyms
- Tharyx coloris Blake 2018