Atractoscion macrolepis, Song & Kim & Kang & Kim, 2017

Song, Young Sun, Kim, Jin-Koo, Kang, Jung-Ha & Kim, Seong Yong, 2017, Two new species of the genus Atractoscion, and resurrection of the species Atractoscion atelodus (Günther 1867) (Perciformes: Sciaenidae), Zootaxa 4306 (2), pp. 223-237 : 228-230

Atractoscion macrolepis sp. nov., Song, Kim & Kim

English name: Large scale lunate caudal fin croaker; Korean name: Keun-bi-neul-cho-seung-kko-ri-min-eo ( Figs 1–2 , Tables 2–3)

Atractoscion aequidens (not of Cuvier, 1830): Henriques et al., 2014 (in part, “LUA, BEN, LUC, NBE, PIN, and HEN”); Henriques et al., 2016 (in part, “the northern clade, AaA”).

Holotype. SAIAB 187117–2 , 284.0 mm SL, Tombua Beach , Angola (15.7795° S, 11.8703° E), caught by hook and line 20 May 2009, collected by Rominha Henriques and Jerraleigh Kruger.

Paratypes. 3 specimens. SAIAB 187117–1 (290.0 mm SL), 187117–6 (270.0 mm SL), 187117–7 (258.0 mm SL), Tombua Beach , Angola (15.7795° S, 11.8703° E), caught by hook and line 20 May 2009, collected by Rominha Henriques and Jerraleigh Kruger.

Diagnosis. Dorsal fin soft rays, 27–28 (28); pored lateral line pored scales, 71–74 (73); pectoral fin length 18.0–19.5% of SL; caudal fin emarginate; distributed in south-western Africa, including Angola and Namibia.

Description. D. X, 27–28 (28); A. II. 9; P1. 17; P 2. I, 5; C. 9 + 5; LLp. 71–74 (73); Vertebrae 24; GR. 5 + 1 + 7–8. The counts and measurements for four specimens are given in Tables 2 and 3. Largest examined specimen was 290.0 mm SL. Overall view of body is shown in Figure 2 .

Body slightly compressed, large, its depth moderate, and slightly tapering towards tail; head large, its depth low; eye large and circular; interorbital region depressed, slightly concave. Two pairs of nostrils on anterior side of eyes; anterior nostrils circular, posterior nostrils an elongated ellipse, anterior nostril smaller than posterior. Snout slightly pointed; mouth terminal, large and strongly oblique; posterior margin of upper jaw extending behind margin of eye; all teeth of upper and lower jaws depressible, cardiform or pluriserial, and well-developed; teeth in outer row larger than those in inner row in upper jaw; teeth on lower jaw equal; teeth on vomer or palatines absent. Barbels and sensory pores on lower jaw absent. Operculum board, large; opercle with two spines on margin. Gill rakers of first gill arch short, blunt, dentate; 5 on upper limb and 8–9 on lower limb. Origin of dorsal fin above hind pectoral fin; dorsal fin with X slender spiny rays, followed by a deep notch and 27–28 soft rays, spines higher than soft rays. End of dorsal-fin base located beyond posterior base of anal-fin. Pectoral fin small with pointed tip extending below the 7th to 8th dorsal fin spine. Origin of pelvic-fin slightly behind origin of pectoral fin, fin with an axillary scale. Origin of anal-fin located below and between dorsal-fin soft rays 19–20. Lateral line starting from above gill opening and extending to margin of caudal fin, and comprising 71–74 (mode 73) relatively large pored scales. Caudal fin concave in mid region; upper lobe longer than lower lobe. Anus located closer to origin of anal fin than to pelvic fin. Body covered with scales except for preorbital region; overall body covered with small ctenoid (rough) scales, head with cycloid (smooth) scales. Swim bladder well developed with thick wall; carrotshaped, with a pair of horn-like anterior appendages; not entering head. Sagittal otoliths thick, large with a tadpoleshaped impression; sulcus head broad, tail short, J-shaped.

Colouration when fixed: body overall light brown; dorsal region dark brown; ventral part of body light brown; snout tip dark drown; around anterior nostrils blackish; dorsal and caudal fin margins blackish; pectoral fin filament dark yellowish, pectoral fin base dark; behind base of pectoral fin intangible dark brown pattern; membrane of dorsal fin light brown; anal fin, pelvic fins pale yellow; margin of caudal fin yellow, its central region dark brown.

Geographic distribution. Angola to Namibia, west–southern Africa.

TABLE 2. Comparison of meristic and morphometric characters among congeneric species in genus Atractoscion (in current).

Atractoscion aequidens Atractoscion nobilis Atractoscion atelodus Atractoscion macrolepis sp. nov. Atractoscion microlepis sp. nov.

1 Dorsal fin rays

Counts n 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 Atractoscion aequidens (South 2 1 1 Africa)

* Otolithus aequidens 1 (South 1 1 Africa)

Atractoscion nobilis (California) 3 2 1

Atractoscion atelodus (Australia) 5 4 1 ** Otolithus teraglin 2 (Australia) 1 1 Atractoscion macrolepis sp. nov. 4 1 3 (Angola)

Atractoscion microlepis sp. nov. 16 9 6 (1)3 (Oman)

continued.

continued.

Lateral line pored scales

Counts n 7 0 7 1 7 2 7 3 7 4 7 5 7 6 7 7 7 8 7 9 8 0 8 1 8 2 Atractoscion aequidens (South Africa) 2 2 Atractoscion atelodus (Australia) 4 1 1 1 * Otolithus teraglin 2 (Australia) 1 1

Atractoscion macrolepis sp. nov. 4 1 1 1 1 ( Angola)

Atractoscion microlepis sp. nov. 1 5 1 2 5 2 2 1 2 (Oman)

Parenthese indicate sampling location. One asterisk was original description of A. aequidens and two asterisk is synonymized with A. atelodus . 1 Cuvier (1830), 2 Macleay (1880), 3 Jawad et al. (2012).

Etymology. The specific name, macrolepis , refers to the large scales.

Comparisons. The new species A. macrolepis sp. nov. can be distinguished from A. aequidens by the following combination of characters: the mode number of lateral line pored scales (73 for A. macrolepis sp. nov.; 76 for A. aequidens ), its distribution ( Angola and Namibia for A. macrolepis sp. nov.; South Africa for A. aequidens ) ( Figs 1–2 , Table 3). Based on molecular markers, Henriques et al. (2014) reported that A. aequidens from southern Africa comprises two populations ( South Africa and Angola / Namibia), and also noted differences in meristic characters including the mode number of pored lateral line scales: 72 for the northern clade (AaA) of A. aequidens in Angola, and 75 for the southern clade (AaSA) in South Africa ( Henriques et al. 2016). These meristic counts correspond closely to those of A. macrolepis sp. nov. in the present study. The neighbour joining tree based on mtDNA COI sequences identified four clades. Among these, the K2P distances clearly distinguished A. macrolepis sp. nov. from A. aequidens (3.7–4.4%) ( Table 4). These results are consistent with the molecular data of Henriques et al. (2014). A. macrolepis sp. nov. also differs from A. aequidens in terms of the pectoral-fin length as a percentage of the SL (18.0–19.5% for A. macrolepis sp. nov. and 12.4–16.9% for A. aequidens ) (Table 2).

Figures

FIGURE 1. Map showing the distribution area of Otolithus aequidens, MNHN A – 5586 (*), Atractosion atelodus, BMNH 1886.6. 19.9 (□), Otolithus californiensis, NMW _ 31129 and Otolithus californiensis, MCZ 10898 (Ǫ), Otolithus teraglin, AMS I. 9773 (□), Atractoscion macrolepis sp. nov., SAIAB 187117 – 1, 2, 6 and 7 (Δ), Atractoscion microlepis sp. nov., PKU 9312 – 9316, 10774 – 10783 (●).

FIGURE 2. Photographs of the type specimens. (A) Atractoscion atelodus, holotype, BMNH 1886.6. 19.9, 263.0 mm SL, Australia (previously reported as Otolithus atelodus); (B) Atractoscion macrolepis sp. nov., holotype, SAIAB 187117 – 2, 284.0 mm SL, Tombua beach of Angola; (C) Atractoscion microlepis sp. nov., holotype, PKU 9315, 280.0 mm SL, Gulf of Oman, illustration of dorsal view of swimbladder (left below) and sagitta in otolith (right below).