Dermatias platynogaster

Dermatias platynogaster Smith and Radcliffe in Radcliffe, 1912

Languages: English

Overview

Biology

Like many species of ceratioid anglerfishes, D. platynogaster is known from relatively few specimens (n=3) and thus, little is known about even the most basic aspect of this species' biology.

Description

Metamorphosed females of D. platynogaster are distinguished from those of all other genera of the family in having an unusually deep caudal peduncle (21.6–23.8% SL); a blunt snout and short, highly convex frontals resulting in an extremely short head (29.7–30.5% SL); and remarkably few teeth in the jaws (20–32 in the upper jaw, 20–31 in the lower jaw).

Metamorphosed females of D. platynogaster are further unique in having the following combination of character states:  Vomerine teeth are present.  The sphenotic spines are well developed (their length 2.9–3.6% SL) and directed dorsolaterally.  The lower jaw bears a stout symphysial spine.  The hyomandibular has a double head.  The quadrate spine is well developed (its length 2.5–5.0% SL), but the articular spine is less than one-half the length of the quadrate spine.  The posterior margin of the opercle is deeply notched.  The subopercle is long and narrow, its dorsal end tapering to a point (the posterior margin without indentation), its ventral end oval in shape (without an anterior spine or projection).  The caudal-fin rays are without internal pigmentation.  The illicium is considerably longer than the length of the esca bulb.  The pterygiophore of the illicium emerges on the snout from between the frontal bones, its anterior end exposed, its posterior end concealed beneath the skin.  The first ray of dorsal fin is well developed.  There are 6 dorsal-fin rays and 4 anal-fin rays .  The pectoral-fin lobe is short and broad (its length 6.6–8.9% SL), shorter than the longest rays of the pectoral fin (16.3–19.9% SL).  There are 15–16 pectoral-fin rays.  The skin is smooth and apparently naked, without dermal spinules (but specimens are unavailable for clearing and staining).  Darkly pigmented skin of the caudal peduncle extends well past the base of the caudal fin (only three known specimens, 134–175 mm; material unavailable for internal osteological examination).

Type Information

Type specimen(s)

Holotype: USNM 70269, 134 mm, female.

Type locality

Albatross, Philippine Expedition, station 5463, near Sialat Point Light, off east coast of Luzon, Philippine Islands, Western North Pacific, 13º40'57"N, 123º57'45"E, beam trawl, 300 fathoms (549 m), 16 June 1909.

Synonymy

Brief synonymy

Dermatias platynogaster Smith and Radcliffe, in Radcliffe, 1912:206–207, pl. 17, fig. 3 (original description, single specimen).  Pietsch and Kharin, 2004:123, 124, figs. 1, 3, 4 (resurrection from synonymy of Oneirodes eschrichtii).  Kharin and Pietsch, 2007:806, figs. 1, 2 (additional specimen, off Queensland, Australia).

Dolopichthys platynogaster:  Regan, 1926:29–30 (brief description after Smith and Radcliffe, in Radcliffe, 1912; in key).  Bertelsen, 1951:79, 81 (one of 22 nominal species placed in the Oneirodes eschrichti-group).  Pietsch, 1974a:44, 53, 102, table 9 (a synonym of Oneirodes eschrichtii).

Dolopichthys (subgenus Dermatias) platynogaster:  Parr, 1927:14 (in key).  Regan and Trewavas, 1932:68, fig. 95 (brief description after Smith and Radcliffe, in Radcliffe, 1912; in key

Pietschichthys horridus Kharin, 1989:158–160, figs. 1, 2 (original description, single specimen).  Pietsch and Kharin, 2004:123, 125, figs. 2, 4 (a junior synonym of Dermatias platynogaster).

Description

Diagnostic Description

Metamorphosed females of D. platynogaster, the only species of the genus Dermatias, are distinguished from those of all other genera of the family in having an unusually deep caudal peduncle (21.6–23.8% SL); a blunt snout and short, highly convex frontals resulting in an extremely short head (29.7–30.5% SL); and remarkably few teeth in the jaws (20–32 in the upper jaw, 20–31 in the lower jaw).

Morphology

The body of metamorphosed females is moderately short, somewhat fusiform, its depth approximately 45–55% SL.  The snout is blunt; the head extremely short (29.7–30.5% SL).  The mouth is small, the opening almost horizontal, and the cleft extending slightly past the eye.  The opercular opening is unusually large, 19.4–22.5% SL.  The illicium length is 15.3–17.5% SL.  The esca, remarkably similar to those of some species of Oneirodes, bears a stout, internally pigmented anterior escal appendage approximately as long as the length of the escal bulb; a pair of medial escal appendages, each consisting of a dense cluster of slender filaments, some slightly longer than length of the escal bulb, and each with a darkly pigmented distal tip; a small rounded terminal papilla, with a single terminal pigment spot; and a simple unpigmented filamentous posterior escal appendage somewhat longer than the length of the escal bulb.

The teeth in the jaws are slender, recurved, and all depressible, those in the lower jaw slightly larger than those of the upper jaw.  The longest tooth in upper jaw measures 2.4–3.1% SL; the longest in lower jaw is 3.4–3.7% SL.  There are 20–32 teeth in upper jaw and 20–31 in the lower jaw.  There are 4–6 teeth on the vomer.  The second and third pharyngobranchials are both well developed and toothed.

The following measurements are expressed in percent SL:  head length 29.7–30.5; head width 25.5–29.1; head depth 33.7–36.6; least outside width between frontals 9.1–10.9; length of premaxilla 22.4–24.0; length of lower jaw 25.2–33.6; length of lower fork of opercle 19.7–22.5, upper fork 10.9–14.9; length of subopercle 8.6–11.3.

Size

Known from only three metamorphosed females, 134–175 mm standard length.

Ecology and Distribution

Distribution

All three known specimens of Dermatias platynogaster were collected in the Western North Pacific Ocean, with gear fished on the bottom:  one off Luzon in the Philippines taken with a beam trawl in relatively shallow water (549 m); another in the vicinity of the Magellan Seamounts, east of the Mariana Islands, with a bottom trawl fished at a maximum depth of 1342 m; and the third from the Townsville Trough, off Queensland, Australia, with a bottom trawl fished at 1188 m.

Reproduction

Although males are unknown, D. platynogaster is probably like many species of the family Oneirodidae in that they never become parasitic. Spawning and fertilization may take place during a temporary sexual attachment that does not involve fusion of male and female tissues.

Trophic Strategy

As with nearly all species of deep-sea anglerfishes, D. platynogaster lures prey to its mouth with bioluminescence emitted from the esca. Unlike most deep-sea fishes that produce bioluminescence, light produced by ceratioid anglerfishes is not endogenous, but rather the product of a bacterial community in the esca.

Taxonomy

  • Pietschichthys horridus Kharin, 1989 (synonym)