Head and otolith morphology of the genera Hymenocephalus, Hymenogadus and Spicomacrurus (Macrouridae), with the description of three new species Author Schwarzhans, Werner text Zootaxa 2014 2014-11-28 3888 1 1 73 journal article 10.11646/zootaxa.3888.1.1 1175-5326 10086415 1B437AE1-CF28-4C1B-95B6-C31A295905A0 Hymenocephalus neglectissimus Sazonov & Iwamoto, 1992 Figs. 35A–C , 37 Hymenocephalus neglectissimus Sazonov & Iwamoto, 1992: 56 ( type locality: Sala y Gomez Ridge, Prof. Shtokman cr. 18, sta. 1964). Hymenocephalus neglectissimus : Iwamoto & Merrett, 1997: 523 (reference values only). Material examined. 2 specimens ZMMGU P-18221, 105 and 112 mm TL, 23°33’S , 89°11’W , 563– 590 m . Diagnosis (after Sazonov & Iwamoto with additions). Pelvic fin rays 8; pectoral fin rays 13–15; gill rakers 16–21. Barbel moderately long, 15–28% HL. Black blotch on dorsum short, with clear-cut outline. Orbit very large, 44–55% HL along the longest diameter, slightly oblique. Snout rounded, not protruding, 10–15% HL. Ventral striae extending to about ⅔ the distance from pelvic fin bases to periproct. Infraorbital width 5–8% HL. Otolith very compressed with broad, pointed predorsal lobe, OL:OH = 0.8. Comparison. Hymenocephalus neglectissimus is a small species that is characterized by its large orbit size in combination with a long barbel and a narrow infraorbital width and narrow infraorbital supporter. Sazonov & Iwamoto used the sharp edged, short black blotch on the dorsum as a further character to distinguish H. neglectissimus from the co-occurring H. semipellucidus (long and eroded outline). FIGURE 35. A–C: Hymenocephalus neglectissimus : A–C—ZMMGU-P 18221, A—Lateral view of head, B—Dorsal view of head, C—Schematic outline drawing of formalin eroded otolith. D–H: Hymenocephalus semipellucidus , ZMMGU-P 18205: D—Lateral view of head, E—Anterior view of otolith, F, H—Inner faces of otoliths, G—Ventral view of otolith. Description. Head morphology (n = 1) ( Fig. 35A–B ): snout short, rounded, not projecting, 10–15% HL, orbit diameter very large, 42–50% HL, 44–55% HL along the longest diameter, slightly obliquely oriented, interorbital width about 40–50% HW. Barbel moderately long, 15–20% HL (up to 28% HL according to Sazonov & Iwamoto), reaching slightly beyond vertical through anterior margin of orbit. Head canals well developed, infraorbital width 5–8% HL, supraorbital canal with 4 segments, width 6% HL, supratemporal canal indistinct, above segment 3 of supraorbital canal, preopercular canal width 10% HL, postorbital-preopercular interspace 4% HL. Infranasal supporter short; infraorbital very short and narrow, 25% OD; preopercular supporter short, 4% HL, with straight rear margin. Otolith morphology (n = 1) ( Fig. 35C ): otolith large; OL:OH = 0.8. No sufficiently well preserved otolith was retrieved from any of the studied specimens. An outline could be reconstructed from one otolith, which has a very compressed shape and a broad, dorsally pointed predorsal lobe. Distribution ( Fig. 37 ). Hymenocephalus neglectissimus is only known from the Sala y Gomez Ridge.