Hymenocephalus aeger Gilbert & Hubbs, 1920

Schwarzhans, Werner, 2014, Head and otolith morphology of the genera Hymenocephalus, Hymenogadus and Spicomacrurus (Macrouridae), with the description of three new species, Zootaxa 3888 (1), pp. 1-73 : 58-59

publication ID

https://doi.org/ 10.11646/zootaxa.3888.1.1

publication LSID

lsid:zoobank.org:pub:1B437AE1-CF28-4C1B-95B6-C31A295905A0

DOI

https://doi.org/10.5281/zenodo.10238857

persistent identifier

https://treatment.plazi.org/id/463A8F36-FF89-FFC2-1297-99D8E3BEFBE8

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Felipe (2021-06-15 04:07:37, last updated 2023-12-01 02:02:54)

scientific name

Hymenocephalus aeger Gilbert & Hubbs, 1920
status

 

Hymenocephalus aeger Gilbert & Hubbs, 1920 View in CoL

Figs. 30A–G View FIGURE 30 , 37 View FIGURE 37

Hymenocephalus striatissimus aeger Gilbert & Hubbs, 1920: 531 View in CoL (type locality: 00°15’N, 127°24’E).

Hymenocephalus striatissimus aeger: Iwamoto & Williams, 1999: 178 View in CoL .

Material examined. 11 specimens; 1 specimen MNHN 2006-0159 About MNHN , 07°44’S, 156°29’E, 518–527 m GoogleMaps ; 1 specimen MNHN 2006-0218 About MNHN , 08°09’S, 157°01’E, 460–487 m GoogleMaps ; 3 specimens MNHN 2006-0556 About MNHN , 91 About MNHN + – 140 mm TL, 08°16’S, 160°04’E, 430 m GoogleMaps ; 1 specimen WAM P.30578-002, 121 mm TL, 17°57’S, 118°17’E GoogleMaps ; 1 specimen ZMUC P375844 View Materials , 84 View Materials + mm TL, Kai Islands ; 1 specimen ZMUC P 375854, 127 mm TL, Kai Islands ; 1 specimen ZMUC P375856 View Materials , 91 View Materials + mm TL, Kai Islands ; 1 specimen ZMUC P 375857, 126 mm TL, Kai Islands ; 1 specimen ZMUC unregistered, 05°46’S, 132°52’E GoogleMaps .

Diagnosis. Pelvic fin rays 8; pectoral fin rays 13–15; gill rakers 19–23. Barbel long, 20–25% HL, reaching beyond a vertical through anterior rim of orbit. Orbit 35–40% HL. Snout obtuse, slightly protruding, 15–18% HL. Ventral striae extending to about ⅔ the distance from pelvic fin bases to periproct. Infraorbital supporter long, 70–90% OD. Otolith compressed, OL:OH = 0.9–1.0; colliculi fused; pseudocolliculum long, TCL:PCL = 1.25–1.45.

Comparison. Hymenocephalus aeger was established by Gilbert & Hubbs (1920) as a subspecies of H. striatissimus on the basis of a longer barbel and a smaller eye. The difference in the eye (orbit) size was not verified from the specimens examined, but the longer barbel is quite distinct. In addition, the otoliths are slightly less compressed than those of the other species of the striatissimus Group (OL:OH = 0.9–1.0 vs 0.75–0.9). This subtle difference in otolith proportions further supports the recognition of a separate taxonomic entity.

Description. Head morphology (n = 2) ( Fig. 30A View FIGURE 30 ): Snout rather short and obtuse, only slightly projecting, 15–18% HL, orbit diameter large, 35–40% HL, interorbital width 60–70% HW. Barbel long, 20–25% HL, reaching slightly beyond a vertical through anterior rim of orbit. Head canals well developed, infraorbital width 11–14% HL, supraorbital canal with 4 to 5 segments, width 10–15% HL, supratemporal canal rarely identifiable, above segment 3 or 4 of supraorbital canal, preopercular canal width 12–16% HL, postorbital-preopercular interspace 4–7% HL. Infranasal supporter moderately large; infraorbital supporter long, extended below almost entire length of orbit, 70–90% OD; preopercular supporter moderately long, 5–8% HL, with straight rear margin.

Otolith morphology (n = 10) ( Fig. 30B–H View FIGURE 30 ): Otolith large; OL:OH = 0.9–1.0; OH:OT = 3.5. Dorsal rim with very large, moderately broad, smooth predorsal lobe, distally marked by small concavity, inclining to posterior tip; posterior tip slightly expanded, positioned at about level of sulcus termination; ventral rim deep, regularly curved, smooth, deepest anterior of the middle; anterior rim high, subvertical to nearly vertical. Inner face slightly convex, with median sulcus. Colliculi completely fused, terminating far from anterior and posterior tips of otolith; pseudocolliculum very long. TCL:PCL = 1.25–1.45. Dorsal depression small, indistinct; ventral furrow distinct, close to ventral rim.

Discussion. Gilbert & Hubbs (1920) studied a large number of specimens of the three nominal subspecies of H. striatissimus , and recorded that they found intergrades between H. striatissimus aeger and H. s. torvus along the Tawi Tawi Archipelago of the Philippines, which led them to establish this form as a subspecies of H. striatissimus . I was unable to verify their observation of intergrades, but found a specimen from off the nearby Jolo Island in the collection of ZMUC (P375860), which I consider as H. striatissimus ( Fig. 32B–C View FIGURE 32 ). Since otoliths seem to present a further character helpful to identify H. s. aeger , I now tentatively propose full species rank for H. aeger , subject however to verification of a more detailed and possibly statistical assessment of this difficult species group.

Distribution ( Fig. 37 View FIGURE 37 ). Specimens studied and considered valid for H. aeger are from off NW-Australia, off southern New Guinea and off the Solomon Islands.

Gilbert, C. H. & Hubbs, C. L. (1920) The macrouroid fishes of the Philippine Islands and the East Indies. United States National Museum Bulletin, 100 (1), 369 - 588. http: // dx. doi. org / 10.5962 / bhl. title. 13637

Iwamoto, T. & Williams, A. (1999) Grenadiers (Pisces, Gadiformes) from the continental slope of Western and northwestern Australia. Proceedings of the California Academy of Sciences, 51 (3), 105 - 243.

Gallery Image

FIGURE 30. Hymenocephalus aeger: A—ZMUC P375844, lateral view of head. B–H—Otoliths, B—Anterior view, C, E–H—Inner faces, D—Ventral View, B–D—ZMUC P375844, E—ZMUC unregistered, 05°46’S, 132°52’E, F—MNHN 2006- 0218, G—ZMUC P375857, H—ZMUC P375856.

Gallery Image

FIGURE 32. Hymenocephalus striatissimus: A—ZMUC P15-5-1914, lateral view of head. B–C—ZMUC P375860, B—Lateral view of head, C—Dorsal view of head. D–F—Otoliths, E–F—Inner faces, D—Ventral view, D–E—BSKU 110412, F—BSKU 110102.

Gallery Image

FIGURE 37. Geographical distribution of Hymenocephalus aeger, H. megalops, H. striatissimus, H. torvus, H. grimaldii, H. neglectissimus, H. semipellucidus, H. sp. 1 and H.

WAM

Western Australian Museum

ZMUC

Zoological Museum, University of Copenhagen

Kingdom

Animalia

Phylum

Chordata

Class

Actinopterygii

Order

Gadiformes

Family

Macrouridae

Genus

Hymenocephalus