Asymmetron inferum

Asymmetron inferum   Nishikawa, 2004

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Asymmetron inferum

Classification / Names Populärnamn | synonymer | CoL | ITIS | WoRMS

Leptocardii | Not assigned | Branchiostomidae

Environment: milieu / climate zone / djupintervall / distribution range Ekologi

; djupintervall 229 - ? m (Ref. 766).  Deep-water

Distribution Länder | FAO områden | Ekosystem | Förekomster | Utplanteringar

Northwest Pacific: Japan.

Length at first maturity / Size / Weight / Age

Könsmognad: Lm ?  range ? - ? cm

Short description Morfologi

Body, 14.7 mm long and up to 1.5 mm high, elongated longitudinally and much flattened laterally, tapering gradually towards both ends; preatrioporal region 10.9 mm, atriopore to anus 1 .0 mm, postanal 1.8mm, and urostyloid process 1.0 mm. Rostral fin extensive and semi-circular, clearly separable from other part by dorsal and ventral notches. Dorsal fin very low in anterior two-thirds of body, while becoming much higher posterially. Left metapleuron terminated abruptly and markedly just behind atriopore, while the right confluent with well-developed ventral fin, followed by thin and high caudal fin, somewhat higher than dorsal fin. Urostyloid process separable from dorsal and caudal fins by its own lower dorsal and ventral fins. Dorsal fin-chambers 270, relative length to width for posterior tall ones up to 3.3; preanal fin-chambers indiscernible, but instead, an elongated vacuole detected along ventral side of rectum between atriopore and anus. Myotomes 83 in total, consisting of 58 in preatrioporal region, 9 in region from atriopore to anus, and 16 in postanal, thus giving the myotome formula of 58+9+16=83. A black pigment spot detectable in neural tube just anterior to first myotome. Tentacular ring composed of Ca. 30 tentacles (including a few dorsal-most minute ones), its anterior margin situated at level of axial (=proximal) part of 5th myotome; intertentacular membrane extremely higher in span of 6 tentacles next to much shorter midventral tentacle than elsewhere. Mid-gut coecum elongated, ranging at level from 20th to 48th myotomes. No gonad.

Biologi     Ordlista (t.ex. epibenthic)

Life cycle and mating behavior Könsmognad | Reproduktion | Lek | Eggs | Fecundity | Larvae

Members of the class Cephalochordata are gonochoric. Life cycle: Eggs develop into planktotrophic larva and later on to benthic adults.

Main reference referenser | Koordinator | Medarbetare

Nishikawa, T. 2004 A new deep-water lancelet (Cephalochordata) from off Cape Nomamisaki, South West Japan, with a proposal of the revised system recovering the genus Asymmetron. Zoological Science 21:1131-1136. (Ref. 766)

IUCN Red List Status (Ref. 130435: Version 2025-1)

  Not Evaluated 

CITES status (Ref. 108899)

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

  Harmless

Human uses


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Ytterligare information

Trophic Ecology
Food items (preys)
Födosammansättning
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Predatorer
Ekologi
Ekologi
Population dynamics
Tillväxt
Max. ages / sizes
Length-weight rel.
Length-length rel.
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Life cycle
Reproduktion
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synonymer
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referenser

Internet-källor

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Estimates based on models

Price category (Ref. 80766): Unknown.

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