Halicmetus drypus, Ho & Last, 2018

Ho, Hsuan-Ching & Last, Peter R., 2018, Review of the batfish genus Halicmetus Alcock, 1891 from Australian waters, with descriptions of two new species (Lophiiformes: Ogcocephalidae), Zootaxa 4508 (2), pp. 179-196 : 188-191

Halicmetus drypus sp. nov.

Vernacular name: Pink Shortnose Seabat

Figures 2C , 3 , 5 ; Tables 1–2

Holotype. CSIRO H 6019-01 (66.7), Norfolk Ridge, Tasman Sea , 26°26’S, 167°09’E, 750–774 m, 18 May 2003.

Diagnosis. A species of Halicmetus distinguished by the following combination of characters: body disk moderately broad, ~67% SL; orbit relatively large, ~9.3% SL; interorbital very narrow, ~5.7% SL; illicial trough opening moderately high; mid-dorsal disk with mainly relatively widely spaced, simple spinules and weak coverage of very tiny tubercles, imperceptible without magnification; belly covered with relatively widely spaced, simple and bifurcate spinules, larger tubercles and bucklers absent; dorsal-fin rays absent; pectoral-fin rays 13; dorsal surface pale pink with diffuse darker reddish pattern when fresh, uniformly creamy white when preserved; peritoneal membrane pale with many scattered melanophores (not visible from ventral surface); distal parts of pectoral, pelvic and anal fins pale.

Description. Proportional measurements of specimens, expressed as percentages of SL, and meristic data are given in Table 1.

Dorsal-fin rays 0; anal-fin rays 4; pectoral-fin rays 13. Body depressed; disk subtriangular, slightly broader than long, truncated anteriorly; skull barely elevated anteriorly when viewed in lateral profile; orbit large, directed dorsolaterally; rostrum a bony plate, short to mouth; illicial cavity situated entirely under rostrum, opening broad, wider than high; nostrils located on each side of lateroventral margins of illicial cavity; esca a fleshy bulb with 2 short filaments on dorsal margin.

Mouth small, horizontal, slightly curved; lower jaw slightly beyond upper jaw anteriorly; teeth villiform, small, in wide band in both jaws; quadrangular tooth patches on vomer and palatines. Fifth ceratobranchials bearing large and elongated tooth plates (tongue teeth, sensu Bradbury 1967, 1980).

Gill filaments present only on 2nd and 3rd gill arches; 3–4 gill rakers on 2nd gill arch; gill opening small, at dorsal and inner portion of pectoral elbow. Dermal cirri present, associated with lateral line system on disk margin and tail. Pectoral fins at outer portion of posterior margin of disk; pelvic fins on ventral surface, closer to mouth than anus; anal fin on ventromedial surface at mid-length of tail.

Squamation agreeing well with definition of Ogcocephalus by Bradbury (1980), consisting of close-set tubercles and bucklers, their bases slightly overlapping, forming heavy armor. Numerous simple tubercles covering entire body except for eyes, lips, fins, and anus. Large bucklers present and usually associated with lateral line system and skeleton; those on dorsal surface of rostrum fused together, forming flat bony plate; bucklers along disk margin multifid, each with 5 sharp spinules; small bucklers evenly covered on dorsal surface of body, subequal to neighboring tubercles and imperceptible without magnification; bucklers on frontal ridge of moderate size; bucklers on ventral surface subequal to adjacent tubercles; bucklers on dorsal surface of tail forming two major rows and some scattered one on each side; two rows of bucklers on ventro-lateral side associated with lateral-line neuromasts, those on ventral surface of tail relatively small and forming two regular rows.

Lateral line canal system well developed. Supraorbital series 4; body series 9; premaxillary series 1; cheek series 8; preopercular series 2; subopercular series 7; dorsolateral branch of subopercular series 3; ventral series 1; tail series 10.

Colour. Pale red smoky pattern on pinkish yellow background when fresh; all fins pale; ventral surface paler than dorsal surface. In preserved specimens, dorsal surface uniformly creamy white; all fins and ventral surface pale. Oral cavity and gill chamber pale. Peritoneum membrane dark gray.

Distribution. Known only from the holotype collected from the Norfolk Ridge, Tasman Sea at a depth of 774 m.

Etymology. From the Greek drypus , referring to the pink plant genus Drypis of the Tribe Drypideae , family Caryophyllaceae .

Remarks. An additional freshly caught specimen from eastern Australia similar to H. drypus was photographed by fisheries scientist, Ken Graham ( Fig. 4D ) and thought to be deposited in the Australian Museum. However, a recent search for this specimen was unsuccessful. Halicmetus drypus might be a rare or range restricted species because we examined many specimens collected from Australian waters but discovered only one specimen in collections.

Figures

FIGURE 2. Front view of five Halicmetus species. A. H. marmoratus, CSIRO H 954-03, 57.8 mm SL. B. Halicmetus westraliensis sp. nov., CSIRO CA3647, holotype. C. H. drypus sp. nov., holotype. D. H. ruber, WAM P.31798-003, 65.9 mm SL. E. H. reticulatus, CSIRO H 4070-48, 74.7 mm. All preserved specimens, not to scale.

FIGURE 3. Specimen collection sides of Halicmetus marmoratus (blue circles), Halicmetus westraliensis sp. nov. (red triangles) and Halicmetus drypus sp. nov. (yellow square).

FIGURE 4. Halicmetus westraliensis sp. nov., CSIRO CA3647, holotype, 68.4 mm SL. A. fresh. B. preserved.

FIGURE 5. Halicmetus drypus sp. nov., holotype, CSIRO H.6019-01, 66.7 mm SL, fresh. A. dorsal view. B. ventral view. C. preserved, dorsal view. D. Fresh caught specimen, specimen not retained, photo by K. Graham.