Hoplostethus gigas McCulloch, 1914

Roberts, Clive D. & Gomon, Martin F., 2012, A review of giant roughies of the genus Hoplostethus (Beryciformes, Trachichthyidae), with descriptions of two new Australasian species., Memoirs of Museum Victoria 69, pp. 341-354 : 342-346

Hoplostethus gigas McCulloch, 1914

Giant sawbelly

Figures 1 & 2 ; Tables 1 & 2

Hoplostethus gigas McCulloch, 1914: 101 , plate xix, original description, Great Australian Bight.

Hoplostethus gigas . McCulloch, 1929: 132, listed (“ holotype on deposit in Austr. Mus.”), Great Australian Bight. – Munro, 1958; 79, fig. 548, description ex McCulloch, Great Australian Bight. – Whitley, 1964: 40, listed, Australia. – Scott, 1962: 108, fig., description ex McCulloch, Great Australian Bight. – Woods and Sonoda, 1973: 306, listed, Australia (“possibly a very large japonicus ”). – Kotlyar, 1980: 197, fig. 10, family revision, description ex McCulloch, Australia. – Maxwell, 1980: 66, plate 155, description ex McCulloch, temperate Australia. – Kotlyar, 1986: 126, generic revision, key, description ex McCulloch, Australia. – Paxton and Hanley, 1989: 366, synonymy and Australian distribution. –Gomon, in Gomon et al., 1994 (in part): 403, Fig. 361, description, Great Australian Bight. – Paxton et al., 2006: 769, taxonomy, central south coast of Australia. –Gomon, in Gomon et al., 2008: 424, fig., description, central south coast of Australia. – Moore and Dodd, 2010: 138–141, morphological characters.

Hoplostethus latus (not McCulloch, 1914: 97, fig. 5). May and Maxwell, 1986: 219, fig., description ex McCulloch, Great Australian Bight.

Material examined. Lectotype. AMS I.12766 (307) (herein designated), Great Australian Bight, FIS Endeavour, one of six registered, 27 March 1913.

Paralectotypes (5, 292– 426 mm SL). AMS I.15710-001 (ca. 375; skeleton, S.1285) same data as AMS I.12766; NMV A.20541 (385; formerly E.4298) same data as AMS I.12766; QMB I.1423 (426; formerly E.3238) Great Australian Bight, 33°18' S, 126°47' E, 238–311 m (130–170 fms), February 1913, FIS Endeavour .

Non-types (7, 293– 378 mm SL). CSIRO H.4874-01 (366), CSIRO H.4874-02 (368), CSIRO H.4874–03 (349), CSIRO H.4874–04 (356), CSIRO H.4874–05 (373), CSIRO H.4874–06 (378) Great Australian Bight , 33°19' S, 128°25' E, 180–350 m, collected at end of tow over rough ground near a drop–off to canyon, FV Noble Pearl, demersal trawl, 21 September 1998 ; NMV A.21541 (293) Victoria, south–west of Portland , 38°48' S, 141°44' E, 432–522 m, 19 June 2000, FV Zeehaan, demersal trawl, coll. by K. Graham .

Diagnosis. Pectoral–fin rays 15, rarely 14; total gill rakers on outer side of first arch 18; predorsal scales 9–15; abdominal scutes 9 or 10, few scutes in large individuals with multiple apical points; isthmus lacking scales; body scales adherent; lateral–line scales with tuberculate medial ridge, but no spine; scales on predorsal midline forming low raised ridge; body ovoid and deep, depth 2.0– 2.2 in SL; nape distinctly curved, forehead almost straight to above upper lip; dorsal– and anal– fin spines of moderate thickness; body of adults grey, superimposed with orange–red to red in life, outer margin of soft portions of dorsal, anal and caudal fins greyish to almost blackish; buccal cavity and opercular recess black, vomer, underside of tongue and upper surface of lower jaw stark white. Reaches 525 mm SL.

Description. (See Table 1 for frequencies of values for selected meristic characters.) Dorsal–fin rays VI, 13 ( VI, 14 in 1 of 9); anal–fin rays III, 9; caudal–fin rays 6 + 2 + 9 + 8 + 2 + 6 (6 or 7 + 2 + 9 + 8 + 2 + 6 or 7); pectoral–fin rays 15 (14 in 1 of 9); pelvic–fin rays I, 6; gill rakers 5 + 1 + 12; lateral–line scales 26 + 2 (26 to 28 + 1 or 2 = 28 or 29); transverse scales 13/1/23 (9–13/1/22–24); predorsal scales 9 (9–15); scutes 10 (9 or 10; Table 2); vertebrae 11 + 15; pseudobranch about 46; branchiostegal rays 8.

(See Table 1 for comparative ranges of selected morphometric characters.) Body ovoid and deep, depth 1.98– 2.16 in SL. Head large, its height slightly greater than its length, 110–115% HL; upper profile in front of dorsal fin distinctly curved to above rear of eye, then mostly straight to upper jaw, slightly concave above rear half of eye in some; anterodorsal profile well separated from upper orbital rim; space between eyes wide, interorbital width 28.8–35.2% HL; eye of moderate size, orbital diameter 24.0–32.8% HL; crests of head bones strong, fine spinules on apices at skin surface; depressions between crests moderately deep, hidden by thick skin in adults; infraorbital bones becoming progressively broader with growth; nostrils immediately preceding orbits, posterior nostril two to four times area of anterior nostril; mouth reaching just beyond vertical through hind margin of eye; large, fine denticulate teeth covering oral margins and exposed lateral surfaces of premaxilla and dentary, palatine with posteriorly tapering band of similar teeth, vomer apparently lacking teeth, at least in adults; tip of dentary with ossified knob at symphysis. Preopercular spine short, reaching about 1/4 way from preopercular margin to pelvic–fin base, broad basally in large specimens. Humeral and preopercular spines of similar size. Longest gill raker about 2/3 eye diameter; gill filaments at angle of first gill arch very short, about 1/8 eye diameter and about 1/3 length of longest filaments of pseudobranch.

Body covered with adherent scales, with densely covered, finely spinoid scales above lateral line, posteriorly and low on side, scales above and covered laterally by pectoral fin cycloid (cycloid scales distributed more ventrally in smaller individuals); head naked except for patch of scales on cheek posterior to rear tip of maxilla in about four vertical rows, posteriormost row with about 17 scales; isthmus scale–less; each lateral–line scale with tuberculate ridge but lacking distinct spine; deep serrated abdominal keel formed from greatly enlarged scales (scutes) with slender spine–like apices, most without sculpturing or multiple tips, some striated; scales on dorsal midline in front of dorsal fin slightly but noticeably raised, their spinules complex but not greatly enlarged. First dorsal–fin spine short, subsequent spines distinctly longer but only increasing progressively in length slightly; spines of moderate thickness, those posteriorly progressively thicker with distinct lengthwise striations; first soft ray distinctly longer than last spine, third ray longest, subsequent rays progressively decreasing in length, outer margin of soft dorsal fin curved anteriorly, straight posteriorly. First anal–fin spine short, second short or of intermediate length, and third long; spines of similar robustness to those in dorsal fin. Caudal fin distinctly forked, lobes of moderate breadth and rounded; middle rays about 40% length of longest rays. Pectoral fin moderately short, reaching to beyond anus in large specimens. Pelvic fin reaching to seventh or eighth scute in large specimens.

A large species, largest specimen examined 426 mm SL; reported to 525 mm SL ( McCulloch, 1914).

Colour in life. Head and body grey, obscured by deep reddish orange to red; opercle black suffused with red; buccal cavity and opercular recess black, vomer, underside of tongue and upper surface of lower jaw stark white; fins deep red; membranes between dorsal fin spines grey, marginal strip on soft portions of dorsal, anal and caudal fins dark grey to almost blackish in large individuals (fig. 1).

Pigmentation in alcohol. Slightly dusky above, pale below; opercle dark; buccal and branchial chambers dark, including gill arches and rakers; vomer, palatines, underside of tongue and lower jaw uniformly pale; medial fins and pelvic fins dusky near outer edges.

Distribution. Confined to the southern coast of Australia, documented from the western part of the Great Australian Bight (126°47' E) to southwest of Portland, Victoria (141°44' E) with collection depths recorded between about 188 and 522 m (fig. 2). It is reported to “hang-out at canyon edges” and in areas with “rough ground” (pers. comm. T. Parsons, skipper of ‘FV Noble Pearl ’).

Comments. The type locality given by McCulloch (1914) in his original description of Hoplostethus gigas does not accurately match registration records for specimens collected by the FIS Endeavour we have been able to locate. In his account, McCulloch presented it as Great Australian Bight, 33°18' S, 126°42' E, 130–170 fms (= 238–311 m). The closest locality we have been able to find for specimens identifiable as this species is that of three specimens registered in the South Australian Museum ( SAM F137, formerly AMS E.3236), Western Australian Museum ( WAM P.63-001, formerly E.3237) and Queensland Museum ( QMB I.1423, formerly E.3238). So far, the specimens at the South Australian Museum and Western Australian Museum have not been found, although specimens of Hoplostethus collected by the Endeavour were received and registered by the institutions as indicated, and in both cases, like the Australian Museum material, they were recorded as H. intermedius . As no further Endeavour material identifiable as H. gigas appears to be in the Australian Museum collection, we assume the other six specimens of the type series were distributed to museums elsewhere in Australia, along with an assortment of other “E series” specimens currently in their collections. For instance, in addition to the assumed type of H. gigas in the Museum Victoria collection listed above among Material examined, a specimen of H. latus was received as part of the same gift. That specimen, NMV R 5962 (formerly AMS E.2350) is most likely one of the nine specimens on which Hoplostethus mediterraneus var. latus was based in the same McCulloch publication and is consequently considered a syntype of what is now regarded as the valid species, H. latus .

The ledger of original Endeavour numbers, which is in the care of the Australian Museum, records E.3236, E.3237 and E.3238 as having been collected at 33°18' S, 126°47' E, 130–170 fms and having been exchanged to the Adelaide, Perth and Queensland Museums, respectively. Although identified in the ledger as Hopostethus intermedius these are the specimens of H. gigas listed above. We suspect the discrepancy in minutes longitude is a misinterpretation of the handwritten record or a transcription error. Despite his lone locality for the species, McCulloch indicated the account is based on eleven specimens. We consider it unlikely that all were collected at the one station as specimens of this species are uncommonly rare in collections and the few that do exist were not taken in large numbers. As McCulloch was zoologist at the Australian Museum at the time of publication, we assume he retained at least one type and AMS I.12766 is one of two specimens currently registered in that collection as H. gigas , even though it was registered as Hoplostethus intermedius without locality information on 27 April 1913. No subsequent annotations were made to that ledger entry. The other specimen so identified in the AMS collection is a skeleton ( AMS I.15710-001) prepared about the time of registration. AMS Skeleton Register records in the hand of McCulloch “S.1285, 28 Mar 1913, Hoplostethus intermedius ” with intermedius crossed out and “gigas ” inserted, in the same hand.

Based on our perceptions of human nature, we assume that McCulloch chose to retain the specimen he regarded as the most representative of the species (now regarded as a holotype). We adjudge AMS I.12766 to be that specimen and here designate it lectotype of Hoplostethus gigas McCulloch, 1914 . Other specimens listed above as paralectotypes are considered to also be from the original series.

The redescription presented here is the first since the original description of the species nearly 100 years ago, and includes additional specimens and data ranges. This is the largest of currently described species and is easily separated from other nominal species by its maximum size attained and the combined morphological features comprising 9–15 predorsal scales, 9–10 enlarged abdominal scutes, 15 (rarely 14) pectoral–fin rays, and 18 total gill rakers. It is separable from the two species described below as discussed in the commentary following each treatment.

Figures

Figure 1. Hoplostethus gigas McCulloch, 1914. CSIRO H4874.02, 368 mm SL, photo by Thor Carter.

Figure 2. Collection localities for specimens examined of Hoplostethus gigas (squares), H. melanopeza sp. nov. (circles) and H. grandperrini sp. nov. (diamonds). Red symbols indicate holotypes or lectotype.