Lepadichthys frenatus Waite 1904

Fujiwara, Kyoji & Motomura, Hiroyuki, 2019, Validity of Lepadichthys misakius (Tanaka 1908) and redescription of Lepadichthys frenatus Waite 1904 (Gobiesocidae: Diademichthyinae), Zootaxa 4551 (3), pp. 275-298 : 276-279

Lepadichthys frenatus Waite 1904

[English name: Bridled Clingfish]

Figures 1 , 2 , 3A, B , 4 A–C, 5, 6A, 7, 8, 13, 14, 15I–P, 16, 17; Tables 1–2

Lepadogaster sp.: Kner 1868: 347 (Kanacea Island, Fiji).

Lepadichthys frenatus Waite 1904: 180 , pl. 24, fig. 2 (type locality: Lord Howe Island, Australia); McCulloch 1929: 360 (Lord Howe Island, Australia); Briggs 1955: 139 [in part; Capricorn Group, Australia (based on 2 specimens, BMNH 1933.1.25.216–17), Nouméa, New Caledonia (based on AMS IB. 2234) and Vila Harbour, Vanuatu (based on AMS IA. 4161)]; Whitley 1964: 54 ( Australia); Hayashi & Hayashi 1985: 56 [in part; Heron Island and One Tree Island, Australia (based on 2 specimens, AMS I. 15484-010, 20463-015)]; Francis 1993: 158 (Lord Howe Island and Norfolk Island, Australia); Johnson 1999: 724, fig. 2A [South Solitary Island, Australia (based on AMS I. 22881-001)]; Randall 2005: 506, unnumbered fig. (Coral Sea); Hoese & Bray 2006: 1575 (Thursday Island and Coral Sea Islands); Conway et al. 2017a: 547 [ New Caledonia (based on 2 specimens, ROM 65285, 65289)]; Conway et al. 2018a: 100 (based on AMS I. 27134-018).

Lectotype. AMS I. 6103, 44.9 mm SL, Lord Howe Island , New South Wales, Australia, 31°52′S, 159°08′E, T. Icely.

Paralectotype. AMS I. 3129, 42.8 mm SL, same data as lectotype .

Non-type specimens. 35 specimens, 19.0– 43.2 mm SL. AUSTRALIA: Queensland: AMS IB. 6164, 30.1 mm SL, Swain Reef; AMS IB. 6682, 21.5 mm SL, Heron Island, 23°25′48″S, 151°55′12″E, E. Slater; AMS I. 17445-076, 35.2 mm SL, One Tree Island , 23°30′00″S, 152°04′48″E, F. Talbot et al.; AMS I. 18271-004, 2, 32.1– 33.3 mm SL, One Tree Island , 23°30′00″S, 152°04′48″E, H. Larson; AMS I. 20463-015, 3, 33.1–43.1 mm SL, One Tree Island , 23°30′00″S, 152°04′48″E; BMNH 1933.1.25.216–218, 3, 26.7–36.1 mm SL, Great Barrier Reef, G. Whitley; USNM 360250 , 12 , 32.0– 39.4 mm SL, One Tree Island , 1 m, V. Springer, 27 Nov. 1966. New South Wales: AMS I. 17367-006, 2, 19.7–37.8 mm SL, Lord Howe Island , 31°31′48″S, 159°04′12″E, D. Hoese; AMS I. 20256-013, 3, 33.9–38.1 mm SL, Duncombe Bay , Norfolk Island , 29°00′00″S, 167°55′48″E; AMS I. 20268-026, 39.9 mm SL, Norfolk Island , 29°04′12″S, 167°57′00″E, D. Hoese et al.; AMS I. 27141-010, 43.2 mm SL, Middleton Reef, A. Gill et al.; AMS I. 27155-007, 30.8 mm SL, Elizabeth Reef, A. gill et al. NEW CALEDONIA: BMNH 2000.6 .29.1, 34.0 mm SL, Nouméa, A. Gill et al., 5 Nov. 1997. FIJI: ROM 47021, 25.2 mm SL, Great Astrolabe Reef, 18°46′S, 178°28′W, hand net, R. Winterbottom et al., 5 Apr. 1983. TONGA: AMS I. 46751-033, 2, 19.0– 22.6 mm SL, South Minerva Reef , 23°58′12″S, 178°54′00″W, T. Trnski et al .

Diagnosis. A species of Lepadichthys characterized by the following combination of characters: 14–17 (modally 16) dorsal-fin rays; 12–14 (13) anal-fin rays; 27–29 (29) pectoral-fin rays; upper end of gill membrane level with 6th to 8th (usually 7th) pectoral-fin ray base in lateral view; lower 10th to 12th (11th) pectoral-fin ray base attached to disc base by membrane; 11–14 (12) gill rakers on each arch; head width moderate, 15.4–19.8 (mean 17.7) % SL; disc size moderate, its length 15.1–18.4 (16.8) % SL; anterior, posterior and least interorbital widths 8.4–10.2 (9.4), 12.1–14.7 (13.5) and 2.8–5.9 (4.8) % SL, respectively; dorsal, anal and caudal fins connected by membranes; NC2 (nasal canal pore) usually located before posterior nostril anterior margin; and black stripe from snout tip through eye to posterior region of head.

Description. Measurements and counts are given in Tables 1 and 2, respectively. Body slender, cylindrical, compressed at caudal peduncle ( Fig. 1 ). Head of medium size, depressed anteriorly, its length and width 3.2 (2.6– 3.3) and 6.2 (5.1–6.5) in SL, respectively. Snout moderate, its length 10.8 (8.7–11.7) in SL, tip slightly rounded (bluntly pointed) in lateral view, duck beak-shaped in dorsal view; dorsal profile of snout slightly concave anteriorly. Anterior and posterior nostrils similarly sized, both with a membranous tube, that of former much longer than latter; both visible in lateral view, former located between verticals through posterior point of upper jaw and anterior margin of eye, latter located directly above anterior margin of eye. Eye size moderate, diameter less than snout length, 16.0 (9.6–16.5) in SL. Interorbital region flattened. Anus closer to anal-fin origin than to posterior margin of disc.

Mouth terminal. Upper jaw slightly longer than lower jaw, upper-jaw length 12.9 (9.8–14.1) in SL. Anterior tip of upper jaw extending beyond that of lower jaw; posterior tips of both jaws horizontally level with lower margin of eye (slightly below horizontal level). Upper-jaw lip slightly thicker than lower-jaw lip. Single row of small similarly-sized teeth in both jaws; upper-jaw teeth incisiviform, tips strongly (almost 90 o) curved posteriorly; lower-jaw teeth with pointed conical tips. Premaxillae separated anteriorly by large circular gap in dorsal view ( Fig. 2A, D ). First to third gill arches with two rows of gill filaments [3 gills (sensu Briggs 1955)], 4th arch without filaments. Gill rakers slender, elongate, somewhat pointed. Gill membranes on each side united ventrally, attached to isthmus.

Dorsal and anal fins long, located posteriorly, their lengths 3.7 (2.9–3.9) and 4.4 (3.4–4.7) in SL, respectively. Origin of dorsal fin slightly anterior to vertical through anal-fin origin. First dorsal- and anal-fin rays very short, sometimes buried under skin. Post-dorsal-caudal length 5.2 (4.0–6.3) in dorsal-fin length. Dorsal- and anal-fin heights almost equal, except anteriorly. Pectoral- and caudal-fin margins rounded. Upper and lowermost pectoralfin rays minute; longest pectoral-fin ray extending beyond vertical through posterior margin of disc, its length 7.0 (5.5–8.6) in SL. All soft-fin rays unbranched. Principal caudal-fin rays segmented. Second preural centrum with one or two (lectotype condition not determined) neural spines ( Fig. 3A, B ).

Pelvic fins and pectoral-girdle elements forming a circular “single” type disc, its length and width 6.1 (5.4–6.6) and 7.5 (5.8–7.6) in SL, respectively. Disc region B bell-shaped, same size as disc region A. No disc region C. Anterior and posterior margins of disc regions A and B, respectively, with fringe, latter much longer than former (lectotype damaged). Disc regions A and B with flattened papillae (lectotype damaged); anterior part of disc region A with 3–6 rows of papillae across center (center without papillae in 4 of 18 specimens), both sides of disc region A (except margins) covered with papillae, inner rows somewhat larger than outer rows; disc region B with 5–8 rows of papillae, inner rows somewhat larger than outer rows, anterior part of disc region B without papillae ( Fig. 4 A–C).

Head sensory canal pores well-developed, including 2 nasal, lacrimal and postorbital and 3 preopercular pores ( Fig. 5 ); mandibular canal pores absent. All pores similarly sized; NC 1 located well before anterior margin of anterior nostril; NC 2 located before anterior margin (level with anterior margin or between anterior and posterior margins) of posterior nostril; LC 1 located in front of anterior margin of eye; LC 2 located antero-ventrally below LC 1 (14 of 37 specimens, Fig. 5B ) [just below LC 1 (16 of 37 specimens, Fig. 5E ) or postero-ventrally below LC 1 (7 of 37 specimens)]; PO 1 located just behind posterior margin of orbit; PO 2 on similar horizontal level as PO 1; PR 1 and PR 2 located on ventral surface and lateral to opercle, respectively; PR3 located just below PO 2 (13 of 33 specimens, Fig. 5E ) [antero-ventrally below PO 2 (1 of 33 specimens) or postero-ventrally below PO 2 (19 of 33 specimens, Fig. 5B )]; all pores with membranous tube ( Fig. 5 ).

Coloration in life ( Fig. 6A ): Body generally faintly gray, with anterior and posterior parts slightly whitish and greenish, respectively. Black stripe on snout tip through eye to posterior region of head.

Coloration when preserved: Uniformly yellowish or pale yellow.

Distribution. Known from Thursday Island (Torres Strait Islands), Coral and Tasman seas ( Australia, Vanuatu and New Caledonia), Fiji and Tonga ( Fig. 7 ). The Thursday Island and Vanuatu records were taken from Hoese & Bray (2006) and Briggs (1955), respectively. Other records are based on voucher specimens examined in this study.

Remarks. Lepadichthys frenatus was originally described by Waite (1904), based on 2 specimens from Lord Howe Island, Australia. Although Briggs (1955) and Hoese & Bray (2006) both treated AMS I. 3129 as the holotype of L. frenatus, Waite (1904) had not designated such, his specimens therefore being syntypes. Lepadichthys frenatus is very similar to L. misakius and the two species were previously considered as a single species. Because Waite’s (1904) figure of L. frenatus was based on a single specimen, the features illustrated (e.g., 16 dorsal-fin rays and 13 anal-fin rays) matching AMS I. 6103, we herein designate AMS I. 6103 as the lectotype, following ICZN (1999: article 74.7, recommendation 74B) to clarify the name L. frenatus and avoid further taxonomic confusion, the remaining syntype (AMS I. 3129) becoming a paralectotype.

The left side of AMS I. 17367-006 (37.8 mm SL) from Lord Howe Island lacked a properly formed eye (trace only apparent) ( Fig. 8A ), an abnormal condition. The remainder of the specimen was normal ( Fig. 8B ). Two specimens of USNM 360250 were not measured because of their poor condition.

Because Randall’s (1999) specimen of L. frenatus from the Pitcairn Islands had some diagnostic characters (e.g., gill raker counts) that differed from other specimens examined, the status of the former and distribution record are equivocal, pending further examination.

Figures

FIGURE 1. Preserved (A–F) type specimens of Lepadichthys frenatus. (A–C), AMS I. 6103, lectotype, 44.9 mm SL, Lord Howe Island, New South Wales, Australia; (D–G), AMS I. 3129, paralectotype, 42.8 mm SL, same data as lectotype. (A, D), lateral views; (B, E), dorsal views; (C, F), ventral views; (G), x-radiograph.

FIGURE 2. CT scanned skeleton of Lepadichthys frenatus, AMS IB. 6682, 21.5 mm SL. (A–C), overall shape; (D–F), close up of head. (A, D), dorsal view; (B, E), lateral view; (C, F), ventral view.

FIGURE 3. Radiographs of caudal skeletons of Lepadichthys frenatus (A, B) and L. misakius (C, D). (A), AMS I 20268-026, 39.9 mm SL; (B), AMS I 20463-015, 43.1 mm SL; (C), KAUM–I. 56686, 41.5 mm SL; (D), CMNH-ZF 12210, 45.8 mm SL.

FIGURE 4. Pelvic discs of Lepadichthys frenatus (A–C) and L. misakius (D–F). (A), AMS IB. 6682; (B), AMS IB. 6164; (C), AMS I. 20256-013; (D), BSKU 103919; (E), CMNH-ZF 12460; (F), CMNH-ZF 12091. A–B (with straight lines) and bar indicate disc region (see text) and 1 mm, respectively.

FIGURE 5. Head sensory canal pores of Lepadichthys frenatus. (A–C), BMNH 1933.1.25.216–218, 26.7 mm SL; (D–F), AMS I. 27155-007, 30.8 mm SL. (A, D), dorsal views; (B, E), lateral views; (C, F), ventral views. NC1–2, nasal canal pores; LC1–2, lacrimal canal pores; PO1–2, postorbital canal pores; PR1–3, preopercular canal pores; AN and PN, anterior and posterior nostrils, respectively. Bar indicates 1 mm.

FIGURE 6. Underwater photographs of Lepadichthys frenatus (A) (Lord Howe Island, New South Wales, Australia in 10 m depth: Photo by T. Davis) and L. misakius (B) (Omi-jima island, Yamaguchi, Japan: Photo by S. Inoue). Specimens not collected.

FIGURE 7. Distributional map of Lepadichthys frenatus (blue circles) and L. misakius (red triangles). (A), map of the western Pacific Ocean; (B), map of Japanese waters. Closed and open symbols indicate records based on specimens examined in this study and published literature or photographs, respectively. Arrowheads indicate type locality.

FIGURE 8. An abnormal specimen of Lepadichthys frenatus, AMS I. 17367-006, 37.8 mm SL, Lord Howe Island, New South Wales, Australia. (A), left side; (B), right side.