Neoscopelus serranoi, Bañón & Barros-García & Arronte & Rábade & Rio & Baldó & Carlos, 2024

Bañón, Rafael, Barros-García, David, Arronte, Juan Carlos, Rábade, Sonia, Rio, José Luis Del, Baldó, Francisco & Carlos, Alejandro De, 2024, Diving deeper into the taxonomy of the Neoscopelus species complex (Myctophiformes: Neoscopelidae) with the description of Neoscopelus serranoi sp. nov., Zootaxa (Mar. Biol.) 5529 (3), pp. 487-510 : 491-492

Neoscopelus serranoi sp. nov. Figure 1 ; Table 1

urn:lsid:zoobank.org:act:38169765-6368-4DC2-A77D-806AEE72F9CF

References. Neoscopelus microchir ( Bañón et al., 2002) ; Neoscopelus cf. microchir ( Bañón et al., 2022) .

Etymology. The name of the new species is dedicated to Dr. Alberto Serrano, from the Instituto Español de Oceanografía (IEO-CSIC), leader of the expedition that carried out the scientific sampling at the Galicia bank, an area where this species has been found most frequently.

Holotype. Neoscopelus serranoi sp. nov. MHN USC 25200- 2, 236 mm TL ( Table 1 , Figure 1a ), 17 August 2010; Galicia Bank , 42.666 ºN, - 11.722 ºW, 766 m depth, sample ID: NSM002 ; GenBank registration: OR076048.

Paratypes. Neoscopelus serranoi sp. nov. MHN USC 25200-3 ( Figure 1b ), 187 mm TL, 15 October 2022; Cantabrian Sea, 43.698 ºN, - 3.808 ºW, 608 m depth, sample ID: NSM 004; GenBank registration: OR076047; Neoscopelus microchir IIPB 7/2001 to IIPB 38/2001, 10 April 1999, Galicia Bank, 42.666 N, - 11.700 W, 764 m; Neoscopelus cf microchir , 17 August 2010 MHN USC 25200, Porcupine Bank, 51.9796 N, − 13.2322 W, 705 m depth, sample ID: PCB026; GenBank registration: ON774728; Neoscopelus macrolepidotus MHN USC 25211- 1, 209 mm TL, 18 August 2010, Galicia Bank, 42.687ºN, - 11.689ºW, 766 m depth, sample ID: NSM 001; GenBank registration: OR076049; MHN USC 25211- 2, 167 mm TL, 16 June 2022; Grand Banks, 43.1067 ºN, - 49.4962ºW, 703 m depth, ample ID: NSM 003; GenBank registration: OR076050 ( Table 1 , Appendix 2).

Material comparative. N. macrolepidotus MHN USC 25211- 1, 209 mm TL, 18 August 2010, 42.687 ºN, - 11.689 ºW, 766 m depth; N. macrolepidotus MHN USC 25211- 2, 167 mm TL, 16 June 2022, 43.106, - 49.496 m depth (Appendix 3).

Diagnosis. The new species belongs to the genus Neoscopelus as defined by Nafpaktitis (1977) by having a body fusiform and compressed; head conical and large; large jaws, extended to the back of the orbit; dentary, premaxilla, palatine, and mesopterygoid with villiform teeth; large eyes, its diameter contained 5 times or less in the head length; elongate pectorals, extending posteriorly beyond the anus; adipose fin present; ventrolateral rows of photophores and a series of light organs on the periphery of the tongue.

Differential diagnosis. Neoscopelus serranoi sp. nov. is morphologically very similar to N. microchir from which it differs subtly. Neoscopelus serranoi sp. nov. differs from type specimens of N. microchir , according to Matsubara (1943), in having a shorter anal-fin base (25.7–34 vs 33.7–43.7% HL) and a shorter pelvic fin (40.4–59.6, mean±95% IC=50.1±1.78 vs 61.3–65.8% HL). ( Table 1 ).

It differs from N. macrolepidotus in having a shorter anal-fin base (25.7–34 vs 37.9–44.4 % HL), and more LO photophores (20–24 vs 12–15).

It differs from N. porosus in having a greater eye (20.3–28.8 vs 17.4–21.6% HL), longer pre-anal distance (72.2–79 vs 64.5–71.2% SL), shorter anal-fin base (25.7–34 vs 44.8–51.8 % HL), fewer gillrakers (14–15 vs 17– 22), and fewer LO photophores (20–24 vs 35–40) ( Arai, 1969; Wada et al., 2021).

Morphological revision. A revision of the morphological characters reported in the ichthyological literature for the two Atlantic species, N. macrolepidotus and N. microchir is presented in the Tables 2 and 3 , respectively.

Species Delimitation. The results of the DNA-based species delimitation analyses are summarised in Figures 2 , 3 , 4 and Appendix 4. All analyses have confirmed hidden diversity within the Neoscopelus species except for a single individual of N. porosus (GBGCA 11195-15) from Taiwan.

The new COI sequences labelled as Neoscopelus serranoi sp. nov. were all assembled into an independent MOTU in four of the six analyses (BIN, ASAP, bPTP and mPTP) including four individuals mined from the repositories and assigned to N. microchir (MFLE001-12 from Jamaica, KF489668–KF489669 from South Africa Southern Indian Ocean and PORCU026-22 from Northeast Atlantic) ( Figures 2 , 3 ). GMYC and mGMYC further subdivide this cluster in two groups, one with eighteen Neoscopelus serranoi sp. nov. and one N. microchir (MFLE001-12) sequences and the second with eight Neoscopelus serranoi sp. nov. and three N. microchir sequences (KF489668– KF489669 and PORCU026-22).

For the remaining N. microchir , the DNA analyses revealed three independent MOTUs consistently supported by all analyses; the first with eleven individuals from Taiwan, the second with six sequences from Australia, and the third with four individuals, three of them from the China Sea and the last (AP002921) of unknown origin.

Several MOTUs have also been found in N. macrolepidotus , ranging from three to five depending on the analysis. The sequences assigned to N. macrolepidotus are mostly subdivided into two large groups supported by all the analyses ( Figures 2 , 4 ). The first comprises eight individuals of the Indo-Pacific area and one from the Gulf of Mexico (MG856810). The second group includes between 10 and 12 individuals distributed worldwide. Both groups represent 85% of the N. macrolepidotus individuals used in the present study. Similarly, a single sequence from the Indian Ocean (FOAQ886-22) is always clustered individually. On the other hand, there are two sequences (FMVIC257-08 from Australia and AP012238) that are included in one of the majority MOTU in three analyses (ASAP, mPTP and mGMYC) and are considered as two independent MOTUs for bPTP. BIN and GMYC included AP012238 in a shared cluster but considered FMVIC257-08 as an independent species.

Figures

FIGURE 1. Neoscopelus serranoi sp. nov. a holotype MHN USC 25200-2, 236 mm TL; b paratype MHN USC 25200-3, 187 mm TL.

FIGURE 2. Consensus phylogeny (Maximum Likelihood and Bayesian Inference) of Neoscopelus based on COI gene sequences with the results of six different molecular approaches: BIN, Barcode Index Number; ASAP, Assemble Species by Automatic Partitioning; bPTP, Bayesian Poisson Tree Process; mPTP, multiple Poisson Tree Process; GMYC, General Mixed Yule-Coalescent model and mGMYC, multiple General Mixed Yule-Coalescent model. The proposed Molecular Operational Taxonomic Units (MOTUs) for each analysis are represented as boxes. The colours in the branches indicate the proposed MOTUs in this study. In the first node of each MOTU, both boostrap values (>75) and posterior probabilities (>0.9) are shown. Each individual contains the putative morphospecies, repository and geographic codes: NEA—Northeast Atlantic; JAM— Jamaica; ESA—Eastern South Africa; TWN—Taiwan; WAU—Western Australia; SCS—South China Sea; IO—Indian Ocean; PNG—Papua New Guinea; ESA—Eastern South Africa; TAS—Tasmania; GME—Gulf of Mexico; NZL—New Zealand; NWA—Northwest Atlantic.

FIGURE 3. Map of sampling locations of the Neoscopelus microchir species complex and the proposed Neoscopelus serranoi sp. nov. in red. The diameter of the circle is indicative of the sample size, and the colours correspond to the MOTUs detected in the phylogenetic analysis.

FIGURE 4. Map of sampling locations of the Neoscopelus macrolepidotus species complex and the single specimen of Neoscopelus porosus (in purple). The diameter of the circle is indicative of the sample size, and the colours correspond to the MOTUs detected in the phylogenetic analysis.