Capitellidae sp. (NHM_1486)
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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/CE792592-061A-5F2B-A4A0-6F798C76CC2D |
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treatment provided by |
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scientific name |
Capitellidae sp. (NHM_1486) |
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Capitellidae sp. (NHM_1486) View in CoL Fig. 2 A–G View Figure 2
Material examined.
NHM_613 NHMUK ANEA 2019.7105, coll. 17 Feb. 2015, 12°23.175N, 116°32.92W, 4202 m http://data.nhm.ac.uk/object/be34eb86-fc0c-411c-8eb9-e86774c6515a; NHM_1486 NHMUK ANEA 2019.7106, coll. 04 Mar. 2015, 12°29.70N, 116°39.01W, 4260 m http://data.nhm.ac.uk/object/05d46c60-8b4d-4623-b7ff-2e8089453d7e.
Description.
Species represented by one anterior fragment and one body fragment only. Specimen NHM_1486 posteriorly incomplete, 8 mm long and 0.6 mm wide for about 22 chaetigers (posterior part of fragment is damaged). Preserved specimens creamy white in ethanol ( Fig. 2A View Figure 2 ); live specimens creamy yellow to white semi-translucent ( Fig. 2B View Figure 2 ). Epithelium smooth ( Fig. 2 View Figure 2 ).
Prostomium conical, anteriorly broadly rounded, slightly longer than wide ( Fig. 2C View Figure 2 ). Eyespots not observed. Nuchal organs everted, lightly pigmented, located at posterior border of prostomium. Peristomium as a narrow, smooth, achateous ring.
Chaetigers 1-10 (= thorax) with capillaries only. First chaetiger with chaetae in notopodia only, subsequent nine chaetigers with chaetae in both noto- and neuropodia. All thoracic chaetae slender, bilimbate capillaries ( Fig. 2D View Figure 2 ), arranged in two rows, with alternating longer and shorter capillaries, about 10 chaetae per ramus. Genital pores or lateral organs not observed under light microscopy.
Chaetigers 11-12 are considered transitional between thorax and abdomen marked by appearance of hooded hooks only in neuropodia, but segments are of similar thickness to those in anterior part of body ( Fig. 2E View Figure 2 ).
Abdominal segments enlarged (inflated), without lobe ( Fig. 2A View Figure 2 ). All abdominal chaetigers with capillary chaetae only in notopodia and hooded hooks only in neuropodia. Abdominal capillaries similar to those in thorax, about 15 per ramus. Hooded hooks with long and slender shaft, with swelling around mid-point of shaft; with a main fang and about three rows of small teeth ( Fig. 2F View Figure 2 ); about 15 hooks per ramus. Remainder of body unknown.
Methyl green stain.
Prostomium, chaetigers 4-6 and abdominal chaetigers do not stain (or at best stain very lightly). Peristomium, chaetigers 1-3 and 7-12/13 stain more strongly ( Fig. 2G View Figure 2 ).
Genetic data.
GenBank MN217415-MN217416 for 16S and MN217495-MN217496 for 18S. COI was unsuccessful for this species, no identical matches on GenBank for 16S or 18S. The species is distinct from all other specimens in this study and in our phylogenetic analyses forms an unresolved clade with Barantolla lepte Hutchings, 1974, three Notomastus M. Sars, 1851 and one Heteromastus Eisig, 1887 species ( Fig. 4 View Figure 4 ).
Remarks.
This species is unusual amongst Capitellidae due to its large number of mixed segments (with capillaries only in notopodia and hooded hooks only in neuropodia). Usually, the abdominal chaetigers in Capitellidae bear hooded hooks only, or there are a small number of posterior thoracic and/or anterior abdominal segments that bear both capillaries and hooks. Of the known genera, only Promastobranchus Gallardo, 1968 shows such chaetal distribution. However, it can be distinguished from the other UKSR-collected species in having the first chaetiger with both noto- and neurochaetae and possessing 12 to 13 instead of 10 chaetigers with capillary chaetae in both rami. Therefore, this material represents not only a new species, but based on current morphological criteria supported also by genetic data, a new genus as well. Because the material is not complete (morphology for the posterior end is missing) the species is here not formally described.
Ecology.
Found in the eastern polymetallic nodule province of the CCZ.
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