Travisia sp. (NHM_1244)
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publication ID |
https://dx.doi.org/10.3897/zookeys.883.36193 |
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publication LSID |
lsid:zoobank.org:pub:7ABDE7F0-DD42-4B96-8A13-80E1E59B1515 |
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persistent identifier |
https://treatment.plazi.org/id/FD955417-26C6-5985-843A-7A845E9095F4 |
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treatment provided by |
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scientific name |
Travisia sp. (NHM_1244) |
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Travisia sp. (NHM_1244) Fig. 30 A–G View Figure 30
Material examined.
NHM_1244 NHMUK ANEA 2019.7183, coll. 01 Mar. 2015, 12°15.44N, 117°18.13W, 4302 m http://data.nhm.ac.uk/object/f6906eae-67ec-4d37-83c6-590f3c53df76; NHM_1863 NHMUK ANEA 2019.7184, coll. 13 Mar. 2015, 12°02.49N, 117°13.03W, 4094 m, http://data.nhm.ac.uk/object/fa708aca-6dd1-4b53-8d54-c76a93f43363.
Description.
This species is represented by two specimens only. It is a small species 5.5-6 mm long and 0.7 mm wide for 24 segments, 20 of which chaetigerous and four posterior-most achaetigerous. Preserved specimens pale yellow ( Fig. 30A View Figure 30 ), live specimens milky, semi-transparent ( Fig. 30B View Figure 30 ). Body robust, compact, grub like, anteriorly half enlarged, particularly over chaetigers 11-13, tapering posteriorly, but remaining relatively thick. Body surface rugose, with transverse rows of small, tightly packed squarish lobes.
Prostomium short, smooth, conical ( Fig. 30C, D View Figure 30 ). Peristomium trapezoidal, rugose, with small, tightly packed squarish papillae, appearing in two rows dorsally. Mouth as a transverse slit between chaetigers 1 and 2 ( Fig. 30D View Figure 30 ).
Branchiae absent. Parapodia biramous, located on row with largest lobes, both rami well separated ( Fig. 30E View Figure 30 ). Parapodial lappets present, observable from chaetiger 1 and well developed from chaetiger 6. Chaetigers in anterior half distinctly triannulate, with three transverse rows of small, squarish lobes, subsequent segments becoming less distinctly annulated, with the last four achaetigerous segments uniannulate; lobes always largest on the ventral most row. Interramal sense organs present, best observed on stained specimen ( Fig. 30E View Figure 30 ). Chaetae all long, smooth, slender capillaries ( Fig. 30F View Figure 30 ).
Pygidium very short, thick (slightly longer wide); in distal view with a tightly packed circlet of around 11 lobes ( Fig. 30G View Figure 30 ), of these five large, thick and tightly packed with the ventral most single lobe thickest, dorso-laterally bordered by about six much smaller lobes ( Fig. 30G View Figure 30 ).
Shirlastain pattern.
Stain retained uniformly. Interramal sense organs observed as darkly red stained spots ( Fig. 30E View Figure 30 ). Specimen stain within few (about 5) days.
Genetic data.
GenBank MN217468-MN217469 for 16S and MN217511 for 18S. Travisia sp. (NHM_1244) is sister to Neolipobranchus sp. and fall within a clade consisting of Travisia zieglerae sp. nov. as well as other Travisia species from GenBank ( Fig. 32 View Figure 32 ).
Remarks.
Both UKSR-collected species are morphologically very similar, in having a similar number of segments and in being abranchiate. They can be distinguished by a suite of subtle characters, which in case of Travisia sp. NHM_1224 is represented by only two specimens, so caution is needed. The two species differ somewhat in body shape as Travisia zieglerae sp. nov. is more slender in the posterior half, while Travisia sp. NHM_1224 is thicker ( Fig. 31A View Figure 31 ). The rugosity of transverse rows differs, as the lobes are more tightly packed in Travisia sp. NHM_1244 and looser in Travisia zieglerae sp. nov., at least in the anterior region ( Fig. 31B View Figure 31 ). Another difference is the arrangement of pygidial lobes ( Fig. 31C View Figure 31 ). Finally, difference can be detected upon staining with Shirlastain, where prostomium of Travisia zieglerae sp. nov. stains darkly unlike that of Travisia sp. NHM_1244 ( Fig. 31B View Figure 31 ) and the stain is retained after even 5 days since staining.
Of the known species of Travisia , only five were described as completely abranchiate, with four of these currently valid: T. glandulosa McIntosh, 1879; T. gravieri McIntosh, 1908; T. nigrocincta Ehlers, 1913 and T. fusus (Chamberlin, 1919) with T. abyssorum (Monro, 1930) considered a subjective synonym of T. glandulosa . Type specimens of McIntosh (1879; 1908) and the specimen of Monro (1930) were examined as part of this study. These can be distinguished from the UKSR species as follows:
T. fusus : has a larger body size of 14 mm and 28 chaetigers. Pygidium is divided into 12-14 inconspicuous lobes. Type locality: Pacific Ocean, towards the Marquesas Islands, 0°60'N, 137°54'W, 4504 m.
T. glandulosa ( Fig. 31D View Figure 31 ): similar number of chaetiger to UKSR species (tentatively around 20 chaetigers counted), posteriorly thick, pygidium with circlet of about 12 small lobes; of these inner 4 or 5 also small. Original description of not much help, and McIntosh (1879) expressed doubt about naming the species due to its poor condition. Type locality: Arctic Ocean, Davis Strait, Greenland, 3264 m.
T. gravieri ( Fig. 31E View Figure 31 ): very compact, grub-like, not thinner in posterior half; tentatively about 16 or 17 chaetigers observed. Type locality: North Atlantic, 986 m.
T. nigrocincta : much larger species, up to 34 mm long and 6 mm wide for 25 segments (the smallest specimen reported by Ehlers was 6 mm long and about 2 mm wide for 17 chaetigers), with dark transverse bands; pygidium not described in detail. Type locality: Southern Ocean, Wilhelm II Coast, 2725 m.
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