Leptacanthichthys gracilispinis (Regan, 1925)
Plainchin dreamarm
Leptacanthichthys gracilispinis
photo by Canadian Museum of Nature, Ottawa, Canada

Family:  Oneirodidae (Dreamers)
Max. size:  0.8 cm SL (male/unsexed); 6.9 cm SL (female)
Environment:  bathypelagic; marine; depth range 0 - 2000 m
Distribution:  North Atlantic: including Canada. Also Pacific Ocean.
Diagnosis:  Dorsal soft rays (total): 4-6; Anal soft rays: 5-6. Unique among dreamers in having a well-developed mandibular spine and a very elongate and narrow pectoral fin lobe (Ref. 12204). Dark in color, with the esca unpigmented in patches (Ref.12204). Metamorphosed females distinguished by the following characteristics: extremely well developed articular spine, considerably longer than quadrate spine; wide ethmoid cartilage and vomer, wider than distance between anterolateral tips of lateral ethmoids and frontals; presence of vomerine teeth; depressed ethmoid region, nasal foramina narrow and oval in shape; long frontals, anterior in posterior, overhanging and extending past the anterior limits of ethmoid cartilage and vomer; nearly linear dorsal margins of frontals; ; ventromedial extensions of frontals approach each other on midline, making contact with parasphenoid; frontals separated from prootics; presence of pterosphenoid; anterior end of illicial trough wider and shallower than posterior end; extremely well developed sphenotic spines; symphysial cartilage of upper jaw longer than wide; lower jaw with small symphysial spine; hyomandibula with double head; ; deeply notched posterior margin of opercle; short and broad subopercle, dorsal end rounded to bluntly pointed, ventral end rounded; absence of first pharyngobranchial; well developed second pharyngobranchial; second hypobranchial directly articulates with second basibranchial; caudal fin rays without internal pigmentation; illicium longer than length of esca bulb; pterygoiphore of illicium cylindrical throughout its length, emerging on snout from between frontal bones, anterior end slightly exposed, posterior end concealed beneath skin; well developed first ray of dorsal fin; dorsal fin rays 4-6; anal fin rays 5; long and narrow pectoral fin lobe, longer than longest rays of pectoral fin; pectoral fin rays 18-22; coracoid lacking posteroventral process; simple pelvic bones, expanded distally; skin is naked, without dermal spinules; darkly pigmented skin of caudal peduncle extends well past base of caudal fin (Ref. 86949). Metamorphosed males: long and narrow pectoral fin lobe, longer than longest pectoral fin rays, articulating along the dorsal margin; short and broad subopercle, dorsal end rounded; lower denticular teeth 6; naked skin, without dermal spinules (Ref. 86949).
Biology:  Deep-sea species (Ref. 12204). Males parasitic on the females (Ref. 12204).
IUCN Red List Status: Data deficient (DD); Date assessed: 11 July 2014 Ref. (130435)
Threat to humans:  harmless


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