Nansenia boreacrassicauda Poulsen, 2015

Family:  Microstomatidae (Pencil smelts)
Max. size:  26.8 cm SL (male/unsexed)
Environment:  pelagic-oceanic; marine; depth range 382 - 400 m
Distribution:  Atlantic Ocean: temperate and subarctic.
Diagnosis:  This species is distinguished by the following characters: a 'stubby caudal species' with PCL/PCD ratio 1.20-1.31; predorsal length <50% SL; dentition extensive, falling into high-number teeth group, often noted for the dentary resembling a closely-spaced picket fence; curved vomerine teeth; large eye, approximately 40% of HL; a large crescent of white tissue on posterior half of eye; with large circumorbitals; with concave indentation in posterior margin of operculum (opercular tube), somewhat variable between type materials; with a large ventral strip of bioluminescent tissue associated with large scales, running from isthmus to vent, appearing dark in preservative; with large patches of distinct whitish, fatty tissue present on anterior and posterior parts of preorbital bone, elongated patch bordering all opercular bones, long strip dorsally separating cranial bones from nape, all patches fading in preservative; large and modified lateral-line scales, showing two pointed projections at posterolateral margins below adipose fin, extending several scales onto caudal fin rays; crumenal organ with relatively small accessory cartilage between fifth cerato- and epibranchial, fourth epibranchial with uncinate process, gill rakers on accessory cartilage 6-7, on fifth ceratobranchial 9-10 (total 16), epibranchial-5 + ceratobranchial-4 with 16 gill rakers in total; adipose fin is large, proximal part heavily pigmented; large pineal window present between eyes; with aphakic gap, acorn- or oval shaped; pseudobranch filaments 15-21; otoliths lanceolate, approximately 7.0 mm (3.0% SL) assembled (each broken into two), rostrum long, ventral margin denticles broad and deep, appearing highly convoluted; body colour golden-brownish, scales strongly iridescent when freshly caught, dull brown after preservation in alcohol/formaldehyde (Ref. 104906).
Biology: 
IUCN Red List Status: Not Evaluated (N.E.) Ref. (130435)
Threat to humans:  harmless
Country info:   
 


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