| Family | Scientific Name | Author | Year | Common Name |
| Stomiidae | Aristostomias grimaldii | Zugmayer | 1913 | Nobulb Loosejaw |
Family Malacosteidae (genera Aristostomias, Malacosteus, and Photosotomias) – Mouth large, jaws longer than skull, about 15-30% standard length; membranes forming floor of mouth absent. Chin barbel present or absent. Dorsal fin located well posteriorly, directly above anal fin. Dorsal and ventral adipose fins absent. Postorbital photophore prominent, located posteroventrally to eye (FAO 2002).
All Aristostomias Species: Body without scales or hexagonal scale pockets. Dorsal and anal fins located near caudal fin; adipose fin absent. Dorsal and anal-fin bases approximately equal, or anal-fin base longer than dorsal. Mouth lacks floor, lower jaws not connected by membrane.Pectoral fins present; 2 rows of photophores on each side of isthmus. Chin barbel present; snout longer than eye diameter (FAO 2020).
Aristostomias grimaldii
Unique Characteristics: PV photophores 14-16 in five groups. Pectoral-fin rays 3-10. A series of luminous dots running backwards from eye to PTO. Barbel ending in thickened, poorly defined terminus with no conspicuous bulb. Color dark brown to black. (FAO 2020).
Similar Species:
Aristostomias lunifer, Moon Loosejaw
Moon Loosejaw, Aristostomias lunifer. PV photophores evenly spaced, never in close-set groups or non-linear clusters. Head and body black; pale luminous material forming a prominent, solid or broken crescent extending along the anterior margin of the eye to below SUO (FAO 2020).
Aristostomias tittmanni, Grouplight Loosejaw
Grouplight Loosejaw, Aristostomias tittmanni. PV photophores 17-19 in 5 or 6 groups. Pectoral-fin rays 3-10. A series of luminous dots running backwards from eye to PTO. Barbel with a well-defined bulb. Color dark brown to black (FAO 2020).
References:
FAO. 2002. The living marine resources of the Western Central Atlantic. Volumes 1-3. K.E. Carpenter (ed.). Food and Agriculture Organization of the United Nations, Rome, Italy. 4099 pp. http://www.fao.org/3/y4160e/y4160e00.htm.
(FAO 2020) Sutton, T.T., P.A. Hulley, R. Wienerroither, D. Zaera-Perez, and J.R. Paxton. 2020. Identification guide to the mesopelagic fishes of the central and south east Atlantic Ocean. FAO Species Identification Guide for Fishery Purposes. Rome, FAO. 327 pp. https://doi.org/10.4060/cb0365en.
Welsh, W.W. 1923. Seven new species of fish of the order Malacopterygii. Proceedings of the United States National Museum, 62 (2449): 1-11.