Neobythites monocellatus Nielsen 1999

Neobythites monocellatus Nielsen, 1999

Figure 6; Tables 1, 5

Neobythites monocellatus Nielsen, 1999: 351, figs. 8–9 (off Venezuela, 09°53′N, 59°53′W, 229 m; holotype: USNM 309234).

Diagnosis. Spine on hind margin of preopercle absent or thin and flat; dorsal-fin rays 93–99; anal-fin rays 78–83; pectoral-fin rays 24–27; precaudal vertebrae 12–13; total vertebrae 54–58; pseudobranchial filaments 4–6; long rakers on anterior gill arch 13–15; head length 21–24% SL; pelvic-fin length 17–23% SL, fins not extending beyond anus; orbit length 4.9–7.0% SL and 22–30% HL; longest gill filament 1.4–2.0% SL and 6.2–9.0% HL; dorsal fin with central ocellus with black spot placed well behind vertical line through anus, the ocellus spot distance being 41–51% SL and the spot covering 6–7 dorsal-fin rays, not extending ventrally to body; no vertical bars on body; otolith length 5.0–5.8% SL, sulcus length 4.0–4.7% SL, and ostium height 18–22% sulcus length and 28–34% ostium length.

Distribution and size. Found in the tropical W and SW Atlantic from off Honduras and along the north coast of South America to French Guiana and off Bahia, E Brazil, on the continental shelf and upper slope (117–439 m). Max. size 154 mm SL.

Comparisons. Neobythites pako n. sp. differs clearly from all other steatiticus species in having a very short but distinct single preopercular spine vs. none or only a very weakly formed, flat, or indistinct spine, and in the combination of several colour, meristic, morphometric, and otolith characters (Table 5). It is most similar to N. malayanus and N. stefanovi. From N. malayanus, it differs in longer upper jaw relative to head length in combination with slightly deeper body, shorter pelvic fins and postorbital distance (Fig. 7), and it differs in several otolith characters including shorter and shallower otolith, and shallower ostium relative to SL, sulcus, and ostium length (Table 5; Fig. 3E, F). It differs from the Indonesian population (type locality) of N. malayanus in having more anal-fin rays, fewer pseudobranchial filaments, and shorter preanal distance, from the Vanuatu population in having in longer gill-filaments and from the Philippine population (which is most similar) in having fewer pseudobranchial filaments (Table 6). It differs from N. stefanovi in its absence of dark dorsal-fin margin, higher number of precaudal vertebrae, vertebrae number below dorsal-fin origin, smaller ocellus spot, and shallower otolith ostium (Table 5).

For further comparisons among all other steatiticus group members except for the W Atlantic N. monocellatus, see Uiblein & Nielsen (2018). Neobythites monocellatus differs from N. pako n. sp. in lack of dark stripe along anal fin, more dorsal-, anal- and pectoral fin rays, more pseudobranchial filaments, more developed gill rakers, and longer pelvic fins; N. monocellatus is most similar to six steaticus group species, N. gloriae, N. lombokensis, N. malayanus, N. meteori, N. steatiticus and N. stefanovi, from which it differs in having a combination of relatively high number of dorsal- and anal-fin rays and gill rakers, relatively longer pelvic fins, shorter postorbital distance, and smaller-sized ocellus spot; from the remaining species, N. malhaensis, it differs in fewer pectoral-fin rays, more pseudobranchial filaments, longer pelvic fins, and smaller ocellus spot.

Remarks. One Neobythites malayanus specimen (length 171+ mm) from off Lombok could not be studied in detail due to missing its tail (Table 6). Like N. unimaculatus, N. malayanus should be studied in more detail regarding geographic differentiation (Table 6, Fig. 7).