Neobythites monocellatus Nielsen, 1999

Uiblein, Franz & Nielsen, Jørgen G., 2023, Five new ocellus-bearing species of the cusk-eel genus Neobythites (Ophidiidae, Ophidiiformes) from the West Pacific, with establishment of three new species groups, Zootaxa 5336 (2), pp. 179-205 : 201-202

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 ).

Figures

FIGURE 3. Neobythites otoliths. (A) N.superocellatus n. sp., HT, MNHN 2021-0457, Solomon Sea (M. Krag). (B) N. japonicus n. sp., HT, KAUM -I. 37071, off Okinawa (from left side of head, shown side-reversed; M. Krag); (C) N. jonathan n. sp., HT, MNHN 2002-3883, Solomon Sea (C. Høegh-Guldberg); (D) N. zora n. sp., HT, ZMUC P771324, Fiji (C. Høegh-Guldberg); (E) N. pako n. sp., HT, MNHN 2006-0337, otolith number MNHN-ICOT-001969, Solomon Sea (M. Krag); (F) N. malayanus, ZMUC P77742, Lombok (C. Høegh-Guldberg); all otoliths from right side of head except for (B); with 1 mm scale bars.

FIGURE 6. Four species of the steatiticus group. (A) Neobythites pako n. sp., HT, MNHN 2006-0337, SL 165 mm, Solomon Sea (side-reversed; M. Krag), (B) N. malayanus ZMUC P77742, 138 mm SL, off Lombok (listed in Uiblein & Nielsen 2018; M. Krag); (C) N. stefanovi, ZMUC P77841, PT, 198 mm SL, Gulf of Aden (listed in Uiblein & Nielsen 2018; M. Krag); (D) N. monocellatus, MOVI 39139, 97 mm SL, off E Brazil (listed in Nielsen et al. 2009; G. Brovad); with 10 mm scale bars.

FIGURE 7. Plots of four morphometric characters and SL for visual comparisons between N. pako n. sp. and N. malayanus (the latter separated into 4 populations).