Species Diversity 19: 91–96 Engyprosopon praeteritus from Australia 91 25 November 2014 DOI: 10.12782/sd.19.2.091 The Australian Sinistral Flounder Arnoglossus aspilos praeteritus (Actinopterygii: Pleuronectiformes: Bothidae) Reassigned as a Valid Species of Engyprosopon Kunio Amaoka1,3 and Peter R. Last2 1 Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan E-mail: [email protected] 2 Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart Tasmania 7001, Australia E-mail: [email protected] 3 Corresponding author (Received 24 March 2014; Accepted 26 September 2014) Nine specimens of a flatfish collected from Western Australia were tentatively identified as Arnoglossus aspilos praeteri- tus Whitley, 1950. The original description of this subspecies is brief and the validity of the taxon had not been investigated, despite its inclusion in subsequent short notes and lists. Our examination of the new material and the type series of A. aspi- los praeteritus reveals that this taxon clearly differs from the members of the genus Arnoglossus in having a well-defined in- terorbital space and split hypurals. It differs subtly from A. aspilos (Bleeker, 1851) in appearance, although both taxa closely resemble each other in most counts and proportional measurements. Arnoglossus aspilos praeteritus is herein redescribed and reassigned as a valid species of the genus Engyprosopon, viz., E. praeteritus. This species differs from other species of Engyrposopon in having a series of dark blotches on the dorsal and anal fins and a pair of small black blotches on the caudal fin, and by lacking sexual differences in morphology and coloration. Key Words: Arnoglossus aspilos praeteritus, Engyprosopon praeteritus, Bothidae, redescription, valid species, northwestern Australia. preparation of this manuscript, we also found an image of a Introduction fresh specimen of A. aspilos praeteritus photographed by Sue Morrison and deposited in the Western Australian Museum The bothid subspecies Arnoglossus aspilos praeteritus (WAM P. 32685-001, Fig. 3). In this paper, A. aspilos praet- Whitley, 1950 was briefly described (Whitley 1950) based eritus is redescribed as a valid species of Engyprosopon, and on four specimens collected between Cape Jaubert and Wal- the evidence for its generic reassignment is discussed. lal off Western Australia, and off Darwin, Northern Ter- ritory (Fig. 1). Subsequently, it was described briefly in a handbook of Australian fishes (Munro 1957), included in Materials and methods a checklist of fishes of Darwin Bay (Larson and Williams 1997), and regarded as an Australian variant of Arnoglossus Counts and proportional measurements follow Amaoka aspilos (Bleeker, 1851) in an identification guide to the liv- et al. (1993). Vertebral counts were taken from radiographs. ing marine resources of the Western Central Pacific (Hens- Measurements were made with dial calipers to the near- ley and Amaoka 2001). It is currently considered a junior est 0.1 mm. Institutional abbreviations follow Leviton et al. synonym of A. aspilos (Hoese and Bray 2006; Polack 2014; (1985). Eschmeyer 2014). Recently, we found nine preserved bothid specimens Engyprosopon praeteritus (Whitley, 1950) (60.0–88.2 mm SL) identified as A. aspilos praeteritus in the (Figs 1, 2A, C, D, 3–5, 6A, B; Table 1) Australian National Fish Collections (CSIRO). They had been collected from Shark Bay and Exmouth Gulf, West- Arnoglossus aspilos praeteritus Whitley, 1950: 32, fig. 1 (orig- ern Australia (Fig. 1). Comparisons of these specimens with inal description); Munro 1957: 16, fig. 463 (short descrip- the types of A. aspilos praeteritus showed they are conspe- tion, figure from original description); Larson and Wil- cific. Further comparisons with A. aspilos showed that these liams 1997: 373 (list); Hensley and Amaoka 2001: 3825 nominal taxa have similar meristic and morphometric fea- (note). tures, but differ greatly with respect to the width of the in- Arnoglossus aspilos (not of Bleeker, 1851): Hoese and Bray terorbital space and aspects of their caudal skeleton, both 2006: 1812 (note); Eschmeyer 2014 (note). considered to be diagnostic generic characters. During the © 2014 The Japanese Society of Systematic Zoology 92 K. Amaoka and P. R. Last 47.1); snout length 5.6–7.0 (7.0, 5.9–7.0), upper eye diam- eter 5.4–7.4 (7.0, 6.6–7.4), lower eye diameter 5.6–7.1 (6.8, 6.0–7.1), interorbital width 1.2–3.8 (2.6, 1.2–1.9), length of ocular-side upper jaw 7.7–9.3 (8.8, 7.9–9.3), length of blind- side upper jaw 6.8–8.4 (7.2, 6.8–8.4), length of ocular-side lower jaw 10.9–12.4 (11.9, 11.3–12.8), length of blind-side lower jaw 10.1–12.1 (11.2, 10.5–12.1), caudal peduncle depth 9.7–12.3 (13.0, 10.7–11.6), length of ocular-side pec- toral fin 15.1–19.0 (16.1, 15.8–19.0), length of blind-side pectoral fin 10.9–13.0 (11.8, 11.2–13.0), length of ocular- side pelvic fin 8.8–12.5 (11.4, 9.4–11.4), length of blind-side pelvic fin 8.5–11.4 (9.5, 9.2–11.4), length of base of ocular- side pelvic fin 7.1–9.4 (8.8, 7.7–9.4), length of base of blind- side pelvic fin 2.7–4.9 (3.3, 3.8–4.9), length of longest dorsal fin ray 11.5–14.0 (13.2, 11.3–14.0), length of longest anal fin ray 11.3–13.9 (12.5, 11.3–13.9). Body ovate, deepest at middle of body, its depth nearly half of body length. Caudal peduncle rather shallow, its depth about equal to or slightly less than 1/4 of body depth. Head small, its length about 1/4 of SL; dorsal profile with deep concavity anterior to interorbital region. Snout rather Fig. 1. Collection localities of type series and present specimens long, prominent, length about equal to eye diameter; no ros- of Engyprosopon praeteritus. H, holotype; P, paratypes. Numerals tral spine in either sex. Eyes small, about 70–80% of length refers to number of specimens. of upper jaw, lower eye in advance of upper eye; no orbital spine in either sex. Interorbital region relatively broad, deep- Material examined. Holotype: AMS IA. 4142, male, ly concave, with no distinct ontogenetic or sexually dimor- 57 mm SL, southwest of Cape Jaubert (19°S, 121°E), West- phic difference in its width (Figs 2A, 2C, 2D, 3). ern Australia, 5 m depth offshore, dredge, September 1929. Mouth rather large, oblique; maxilla extending slightly Paratypes: AMS IA. 4141, 53.1 mm SL, sex unknown, same beyond vertical drawn through anterior margin of lower station as holotype; AMS IA. 4284, 43.1 mm SL, sex un- eye; anterior tip of lower jaw slightly projecting beyond tip known, Darwin, Emery Point (12.45°S, 130.30°E) and AMS of upper jaw when mouth closed. No symphysial knob on IA. 4293, 42.1 mm SL, sex unknown, Port Darwin (12.45°S, ventral tip of mandible. Dentition of each side on upper jaw 130.30°E), Northern Territory. Other specimens exam- distinctly asymmetrical in shape and size; teeth on upper ined: CSIRO A 1261, 88.2 mm SL, male, off Cape Peron, jaw conical and uniserial, more or less enlarged anteriorly; Shark Bay (25.30°S, 113.30°E), Western Australia, depth teeth on lower jaw similar to anterior teeth of upper jaw in 11m, 27 August 1953; CSIRO A 1332–1337, 69.0–73.2 mm size and spacing. Tip of vomer projecting far into mouth SL, 4 males and 2 females, Exmouth Gulf between Y-Island cavity. Gill rakers on first arch slender, not serrate, those and Whale Beach (21.57°S, 114.25°E), Western Australia, 5 on upper limb smaller than those on lower limb (Fig. 5B). September 1953; CSIRO A 1338–1339, 60.0–60.5 mm SL, Scales on ocular side moderate in size, deciduous, feebly cte- 1 male and 1 female, Exmouth Gulf (22°S, 114°E), Western noid with very short ctenii (Fig. 5A); tips of both jaws and Australia, 20 August 2003. Fresh image examined: WAM P. snout naked on ocular side; scales cycloid on blind side. 32685-001, 64.7 mm SL, sex unknown, Exmouth Gulf, Y- Dorsal fin highest at point slightly posterior to middle of Island (54.85°S, 28.44°E), depth 7–9 m, otter trawl, 7 May body, its height about half of head length. Anal fin similar 2004, collected by Sue Morrison. to dorsal fin in shape. Pectoral fin on ocular side short and Comparative materials. Arnoglossus aspilos: HUMZ feeble; that on blind side even more so, its length about 70– 185345, 185346, 185347, 185350, and 185352, 80.0–96.5 mm 80% of that on ocular side. Pelvic fin origin at tip of isthmus, SL, 3 males and 2 females, Miyazu Bay, Kyoto Prefecture, fourth ray of ocular side opposite to first ray of blind side. 15–16 m, 17 October 2001. Tip of isthmus at point nearly below posterior margin of Diagnosis. A species of Engyprosopon with a narrowly lower eye. Caudal fin rounded posteriorly, three (rarely two) concave interorbital space; no obvious sexual dimorphism; uppermost and lowermost rays branched. prominent snout; tip of palatine bone distinctly protruding Coloration when fresh (based on WAM P. 32685- into mouth; 3–6 non-serrate gill rakers on upper limb; cau- 001). Body pale brownish on ocular side, without distinct dal fin with pair of small, black submarginal blotches; dorsal blotches or spots; margins of scale pockets highlighted, and anal fins each with series of black spots.