Forsterygion Whitley and Phillips, 1939

Jawad, Laith A., 2008, Second revision of the New Zealand triplefin genus Forsterygion Whitley and Phillips, 1939 (Pisces: Tripterygiidae), Journal of Natural History 42 (47 - 48), pp. 2943-2989 : 2954-2962

Forsterygion Whitley and Phillips, 1939

( Figures 1–2 )

Diagnosis

A genus of triplefins characterized by the following combination of characters: first dorsal fin spines V–VIII; second dorsal fin spines XVIII–XXVI ( Fricke (1994) lists specimens as having 16–17); third dorsal fin rays 11–16; anal fin with 0–2 spines and 23– 31 soft rays; pectoral fin rays 14–21; pelvic fin with 1 spine and 2 soft rays. Total vertebral number 38–48. Eye dorsolaterally oriented. Upper jaw extending to below anterior third of eye. Third dorsal fin similar height to second, membrane between first and second dorsal fins deeply incised. Supraorbital canal with small size pores. Base of caudal fin scaly. Body scales pentagonal. Ctenii peripheral, irregular in size, usually long and conical in shape with concave, levelled base. Latera line canal straight, elongated, transverse over entire length of scale. Denticles present on inter-radial circuli. Tongue present. Straight first circulus ( Figure 1 ). Four infraorbital bones, lacrimal with three processes. Third hypobranchial an inverted ‘‘V’’ shape, with curved tapered end directed anteroventrally and extending beyond second hypobranchial. Four elongated, thin, curved ceratobranchials, fifth ceratobranchial in the form of an elongated postero-laterally tapered plate, fourth ceratobranchial longest, reaching fourth basibranchial, first ceratobranchial shortest, medial and lateral ends flared, dorsal surface of fifth ceratobranchial curved with either three or more rows of long, curved, round teeth, longer teeth bordering posterio-medial margin, remaining rows with even teeth of variable length, some with curved ends. Eight to nine gill rakers crowded on posterior or anterior edge arranged alternatively or oppositely in two lines, one small gill raker at broad base of first epibranchial, gill rakers in groups of three to eight long, stalked, curved, pointed teeth, first three gill rakers on lateral end of each ceratobranchial poorly developed. Infrapharyngobranchial with three or more rows of long, curved teeth with broad base, longer teeth on anterior-medial margin, remaining rows with teeth of variable length. Five pterygiophores anterior to neural spine of first vertebra. No pterygiophore opposite neural spine of first vertebra ( Figure 2 ). No pterygiophore interdigitated between neural spine of first and second vertebrae ( Figure 2 ). Second dorsal fin first pterygiophore anterior to neural spine of fifth vertebra. Segmented fin rays of the third dorsal fin not branched. Pterygiophore of first spine, second spine, first segmented ray, second segmented ray and third segmented ray all anterior to haemal spine of first caudal vertebra. Single pterygiophore supports second spine and first segmented rays. Segmented anal fin rays not branched. Last two segmented rays in third dorsal and anal fin supported by single pterygiophore. Interdigitation less than one-third of respective lengths of neural spine, for second and third dorsal fins, half of respective haemal spine lengths for anal fin. Scapula narrow, dorsal portion closely applied to posterior surface, small scapular foramen. Sutured halves of pelvic girdle with large phalanges. Posteriormost branchiostegal ray narrow. Coracoid with short, broad coracoidal spur. Four long hypurals in two plates, lower plate (1+2), upper plate (3+4), broad. Fifth hypural absent. Broad parhypural. Posterior portion of urostyle conical with narrow base not risen upward. Otolith elliptic shape, thick and rough. Prominent rise of excisural floor in front of usual antristrum position. The straight first circulus, absent fifth hypural, lack of pterygiophore opposite neural spine of first vertebra, urohyal with asymmetrical sides, and otolith elliptic are considered as morphological synapomorphies for Forsterygion , and distinguish this genus from other tripterygiid genera.

Forsterygion varium Schneider (in Bloch and Schneider (1801)) Variable triplefin

( Figures 1 , 3–7 )

Blennius varius Schneider (ex Forster MS) in Bloch and Schneider (1801, p. 178); Cuvier and Valenciennes 1836, p. 414; Forster, in Lichtenstein (1844); Hutton 1877, p. 354; Gill 1893, p. 94–96; Parrott 1936, p. 31; Whitley and Phillips 1939, p. 236; Schultz 1960, p. 282; Scott 1977, p. 153.

Tripterygium varium Cuvier and Valenciennes 1836, p. 414 ; Gunther 1861, p. 277; Hutton 1890, p. 280; Regan 1914, p. 134, 145, 150, pl. 9, Fig. 1 , 2 ; Laird 1953, p. 301, 303, Table 1, pl 5.

Tripterygium varium Richardson 1844, p. 211 ; Gill 1893, p. 94–96, 100, 102, 119; Hutton 1904, p. 46; Waite 1907, p. 32; Waite 1913, p. 1, 3, 7, 9, pl. 3; Thomson 1913, p. 50; Thomson and Anderson 1921, p. 95; McCulloch and Phillips 1923, p. 21; Phillips 1927a, p. 50; Phillips 1927b, p. 14; Parrott 1936, p. 31–39; D.H. Graham 1938, p. 416; D.H. Graham 1939, p. 368; D.H. Graham 1953, p. 327, pls on 328, 329, 331; Laird 1953, p. 79, 82, 86, 87, 89, 90, 94, 111, 112, 121, 136, 137, Tables 1, 2, pls 7, 10, 12; R.V. Grace 1971, p. 132, 133; Doak 1972, p. 103, 104, 106, 107, pl. 45; R.V. Grace 1971, p. 92; R.V. Grace 1973, p. 17; Ruck 1973, p. 1; A.B. Grace 1974, p. 23; R.V. Grace 1976, p. 98; Gordon and Ballantine 1976, p. 34, 133; A.B. Grace 1976, p. 104; Nicholson 1979, p. 136; Willan et al. 1979, p. 452 as Tripterygion ; Housley 1980, p. 87, 88; Nicholson and Roberts 1980, p. 141; Ayling 1982, p. 279, pl. 38; Russell 1983, p. 134, Table 1; Hardy 1986a, p. 146; Dickson 1986, p. 30.

Trypterygiun varium Hutton 1873, p. 263 (part 0); Sherrin 1886, p. 302; Sandager 1888, p. 129; Hardy 1986b, p. 145.

Trypterygium nigripenne (not of Cuvier and Valenciennes) Hutton 1873, p. 263.

Enneapterygius varium Rendahl 1926, p. 9

Enneapterygius varius Rendahl 1926, p. 10 , 11, 12, Fig. 15.

Forsterygion varium Whitley 1956, p. 41 ; Parrott 1960, p. 153, Fig. 56; Graham 1963, p. 169; Morris 1965, p. 141, 145, 148–151; Whitley 1968, p. 80; Russell 1969, p. 109; Hewitt and Hine 1972, p. 84; Scott 1977, p. 157, 161; Francis 1979, p. 69; Housley et al. 1981, p. 38; Thompson 1981, p. 221b, 227, 233, 241, 243, Figs on 228, 230; Holleman 1982, p. 133; Thompson and Jones 1983, p. 95–103; Paulin and Stewart 1985, p. 50; Hardy 1986b, p. 29; Roberts et al. 1986, p. 102; Hardy 1987, p. 47, 51; Hardy et al. 1987, p. 246.

Forsterygion multiradiatum Scott 1977, p. 153 , 157, 159, 161, 163, Fig. 2 , Table 5; Edgar et al. 1982, p. 118, Fig. 104; Last et al. 1983, p. 427, 429.

Diagnosis

A species of Forsterygion with the following set of characters: head and pectoral fin base scaly (latter covered with cycloid scales), no scales on third dorsal fin membrane, ctenoid scales adjacent to but not overlapping base of third dorsal fin membrane. Lateral line scales short, posterior projection absent (present in specimens, 88mm). Dorsal fin formula V-0N-0-1-0-1 (39). Parhypural not fused. Nine procurrent rays in upper lobe, eight in lower lobe; in upper lobe, one procurrent ray opposite upper lobe, six opposite two epurals, two anterior to anterior epural; in lower lobe, one procurrent ray opposite lower lobe, six opposite haemal spine of second preural vertebra, one between haemal spine of second preural vertebra and haemal spine of third preural vertebra. Body with seven vertical bands of reddish-brown to black saddles (broad bands not extending onto ventral surface).

Description

The following counts and proportions (given as times in standard length unless otherwise stated) are based on the neotype and, in parentheses, the range for 73 nontype specimens of 37–100mm SL.

Inter orbit convex. Eyes dorsolateral oriented. Snout moderately sloped; angle 54– 61 °. Supraorbital and anterior nostril tentacles multifid. Upper jaw extending to below anterior third of eye. A moderately large species with body dorsally humped over pectoral fin region before attenuating and becoming laterally compressed posteriorly.

Head length 3.9 (3.7–4.2); predorsal length 5.4 (4.7–5.4); preanal length 2.2 (2.2– 2.4); peduncle length 11.7 (10.7–12.2); peduncle depth 13.1 (12.6–14.3); pectoral fin length 3.8 (3.7–4.0); eye diameter 3.2 (3.1–3.6) in HL; upper jaw length 2.3 (2.2–2.3) in HL; snout length 3.0 (2.9–3.1) in HL.

First dorsal fin spines VI (V–VII); second dorsal fin spines XXIII (XXI–XXV); third dorsal fin rays 15 (12–16); pectoral fin rays 19 (17–21); anal fin with 2 spines and 30 (25–31) soft rays. Discontinuous lateral line with 28–35 tubular scales, no lower lateral line. Total vertebral number 43–48.

First dorsal fin low, about one-half height of second. Third dorsal fin similar height to second, membrane between first and second dorsal fins deeply incised. Spines of first dorsal fin increasing in both length and weight posteriorly. Pectoral fin rays comprising two or three upper simple rays, eight to nine bifurcate rays, lowermost thickened, seven or eight simple rays, uppermost of thickened simple rays longer than adjacent, branched rays, extending posteriorly to between one-half to two-thirds length of second dorsal fin base; outer soft ray of pelvic fin about fourfifths the length of inner soft ray and joined to the latter for between half and threequarters of its length, inner soft ray extends almost to vent, becoming proportionally shorter in largest adults.

Head sensory canals. Suborbital canal lower sensory row dropping toward premaxilla from orbit. Supraorbital canal with small size pores. Postocular canal reaching supratemporal canal, but not extending beyond it. Supratemporal canals meet dorsally, with several small sensory pores. Preopercular-mandibular canal thin with numerous small pores. Frontal, temporal and upper part of otic area covered with fine sensory papillae. Ventral part of preopercular-mandibular canal with six pores, two at base of operculum, two below tip of upper jaw and two at lower jaw symphysis ( Figure 3 ).

Squamation. Head covered with dorsally directed ctenoid scales, extending from the inter-orbital area to nape, in juvenile individuals (, 45mm in SL) this cover absent except for small solitary ctenii distributed irregularly over inter-orbital area and nape. Base of the pectoral fin and belly covered with small cycloid scales. Base of caudal fin scaly. Base of dorsal fins, anal fin, and operculum naked. Body with pentagonal-shaped scales. Cycloid scales in area around anus and genital opening. 10–11 scales rows between anterior end of second dorsal fin and lateral line. Four to five scales between second and third dorsal fins. Sixteen to seventeen scales around caudal peduncle. Scales with smooth anterior margin. Secondary radii present in some body regions. Number of radii in different body regions varying between 9 and 16. Ctenii peripheral, long and conical in shape. Lateral line scales triangular, with a posterior broad projection. Lateral line canal straight, long, transverse over the entire length of the scale surface, with C-shaped anterior and posterior openings, slight constriction at middle. Three separated groups of ctenii on posterior side of lateral line scales. In young individuals (, 45mm), scales smaller, oval. Lateral line scales shorter, posterior projection absent (present in specimens, 88mm). Denticles present on inter-radial circuli, long, broad base, with curved end, spaced, tongue present, with free circuli anteriorly; first circulus straight; oblong focus with smooth inner region and a complete circulus around it ( Figure 1 ).

Osteology. F. varium has the following combination of osteological characters: posttemporal serrated, exposed posteriorly. Ossified, incomplete inter-orbital septum. Four infra-orbital bones with small, thin lacrimal having three processes, broad dorsal, small posterior and broad, short anterior. Ventral and orbital edges of lacrimal rough, second, third and fourth infraorbital bones have wavy ventral edge (especially third element), posterior end of second and anterior end of fourth bones getting smaller posteriorly. Short wedge-shaped, straight-sided basihyal, anterior and posterior edges not straight, with wings, with constriction at posterior end; four basibranchials, well separated, first to third ossified, fourth small and cartilaginous, diamond shaped; first basibranchial rectangular, with short lateral end and flat medial end; second basibranchial short, elongated, waisted, bell-shaped with anterior end broader than posterior; third basibranchial elongated, spindle-shaped, reaching and overlapping fourth basibranchial. Three hypobranchials firmly connected to following ceratobranchials, first hypobranchial longest, third shortest, first and second hypobranchials tubular, straight, third hypobranchial an inverted ‘‘V’’ shape, with curved tapered end directed antero-ventro-laterally extending beyond second hypobranchial, legs equal, broad and separated by wide deep gap. Four elongated, thin, curved ceratobranchials, fifth ceratobranchial in the form of an elongated posterolaterally tapered plate, fourth ceratobranchial longest reaching fourth basibranchial, first ceratobranchial shortest, medial and lateral ends flared, dorsal surface of fifth ceratobranchial curved with more than three rows of long, curved, rounded teeth, longer teeth bordering postero-medial margin, the remaining rows with teeth of variable length, some with curved ends. Eight to nine gill rakers crowded on posterior edge arranged alternatively in two lines, one small gill raker at broad base of first epibranchial, gill rakers in groups of three to eight long, stalked, curved, pointed teeth, first three gill rakers on lateral end of each ceratobranchial poorly developed. Four thin, curved epibranchials, first and second longest with tubular medial and broad lateral ends, third and fourth shortest having medial (third) and lateral (fourth) ends flared and phalanges on posterior surface only. Infrapharyngobranchial with three rows of long, curved, with broad based teeth, longer teeth on anterior-medial margin, remaining rows with teeth of variable length ( Figure 4 ). Oval-shaped urohyal (ventral view) ( Figure 5 ), adze-shaped (ventral view), umbrella-shaped (dorsal view), Y-shaped in transverse section, braizer-shaped (viewed anteriorly), anterior edge straight with slight rise at centre, lateral wings, rounded and forward projected, pointed posteriorly, sides short and asymmetrical, gradually tapered posteriorly. Well-developed, elevated basibranchial attachment. Five pterygiophores anterior to neural spine of first vertebra. No pterygiophore opposite neural spine of first vertebra. No pterygiophore interdigitated between neural spine of first and second vertebrae. Second dorsal fin first pterygiophore anterior to neural spine of fifth vertebra. Segmented fin rays of third dorsal fin not branched. Pterygiophore supporting first segmented ray of third dorsal fin anterior to neural spine of twenty-ninth vertebra. Anal fin with two spines. Pterygiophore of first spine, second spine, first segmented ray, second segmented ray and third segmented ray all anterior to haemal spine of first caudal vertebra. Single pterygiophore supports second spine and first segmented ray. No pterygiophore between second and third dorsal fins. Anal fin rays not branched. Last two segmented rays in third dorsal fin and anal fin supported by single pterygiophore. Interdigitation less than one-third of respective lengths of neural spine, for second and third dorsal fins, half of respective haemal spine lengths for anal fin. Scapula narrow, dorsal portion closely applied to posterior surface, small scapular foramen. Sutured halves of pelvic girdle with large phalanges. Narrow posteriormost branchiostegal ray. Coracoid with short, broad coracoidal spur. Dorsal fin formula V-0N-0-1-0-1 (39). Four long hypurals in two plates, lower plate (1+2) curved upper plate (3+4), broad; dorsal and ventral edges of both plates curved, narrow gap between plates. Fifth hypural absent. Parhypural broad, not fused. Large rounded hole at junction of lower hypural base with parhypural and urostyle. Long, broad, pointed neural spine of second penultimate vertebra. Long, very broad, haemal spine of second penultimate vertebra not reaching posterior edge of lower hypural. Two equally long, broad, curved, blunt epurals, reaching dorsal margin of body the anterior element broader. Fourteen soft rays in caudal fin, no multibranched, one unbranched and six branched (non multibranched) rays in upper caudal lobe; two unbranched and five branched soft rays in lower caudal lobe. Nine procurrent rays in upper lobe, seven in lower lobe; in upper lobe, one procurrent ray opposite upper lobe, six opposite two epurals, two anterior to anterior epural; in lower lobe, six opposite haemal spine of second preural vertebra, one between haemal spine of second preural vertebra and haemal spine of third preural vertebra. Posterior portion of urostyle conical with narrow base not angled upward ( Figure 6 ).

Otolith. Elliptic shape ( Figure 7 ), thick and rough. Mesial surface convex. Lateral surface concave anterio-posteriorly, rough. Irregular dorsal margin. Irregular ventral margin. Posterior end with two prominent ends, the dorsal pointed and longer than ventral. Sulcus acusticus, ostial and homosulcoid present. Long, broad, deep ostium lies along rostrum. Short, broad, deep cauda, with slight downward inclination. Ostio-caudal differentiation present. Crista superior poorly developed. Crista inferior developed. Dorsal margin depressed toward posterior end. Ventral depression absent. Rostrum long, blunt, broad with broad end. Antirostrum short. Excisura wide, notch, angle wide. Excisural lip in raised.

Colour. Head with reddish-brown spots, reddish to brown bands radiating diagonally from eye corner through jaws, spreading from under eye to mouth corner, and across cheek and operculum. Head ventral surface pale, greyish. Iris black with bright gold rim. Brown-black blotches along middle of body, separated by cream-white spots on back. Gill covers pink or mauve. Belly pale. Breeding males darker, greyish black with starkly bluish-white margins to first and second dorsal and anal fins.

Size. 130mm SL.

Distribution

This species is considered to be among the most widely distributed fish species in New Zealand having been recorded from the Three Kings Islands to the Snares Islands and at the Chatham Islands. Introduced to Tasmania , it is now found in regions of the Derwent estuary and D’Entrecasteaux Channel. Generally more abundant above 10m, but common in areas of broken rock on reefs in depths from 0–33m ( Hardy 1989) .

Material examined

Museum specimens (n 573): NMNZ P. 36258, 5, 94–104mm SL, north side of Smoothwater Bay, Jackson Bay , 8 Feb 1999 . University of Auckland specimens: 5, 37– 100mm SL, Ulva Island, Stewart Island , 1 Feb 1998 ; 17, 42– 88mm SL, North Cape, 28 Feb 1999 ; 14, 56– 96mm SL, Three Kings Islands , 1 Mar 1999 ; 14, 61– 88mm SL, Ti Point , 12 Aug 1997 ; 8, 66– 85mm SL, Great Barrier Island , 5 Sep 1997 ; 3, 74– 89mm SL, Nelson Island, Great Barrier Island , 10 Oct 1997 ; 1, 52mm SL, Sphinx Island, Mokohinau Islands , 21 Jan 1998 ; 1, 42mm SL, Stirling Point , 26 Jan 1998 ; 5, 48– 100mm SL, Island Bay , Wellington, 7 Feb 1998 .

Figures

Figure 1. SEM micrograph of F.varium scale showing the straight annulus at the inter-radial area. Scale bar5200 Mm.

Figure 2. Interdigitation of the dorsal fin pterygiophores with the neural spines of the vertebrae in Forsterygion species. Scale bar51mm.

Figure 3. Pattern of head sensory canals of F. varium. (A) Lateral view; (B) Dorsal view; (C) ventrolateral view. Scale bar51 mm.

Figure 4. Gill arches, with gill rakers removed of F. varium (left side only shown). BH, basiyal; BB, basibranchials (three ossified, one cartilaginous shown stippled); CB, ceratobranchials (five); EB, epibranchials (four); HB, hypobranchials (three); IPB, infrapharyngo-branchial plate. Scale bar51 mm.

Figure 5. Ventral view of the urohyal bone of F. varium. Scale bar51mm.

Figure 6. Caudal skeleton of F. varium (procurrent rays in black). NS, neural spine; HS, haemal spine; HY, hypural; PH, parhypural; U, urostyle. Scale bar51 mm.

Figure 7. SEM micrograph of F. varium (53 mm, SL) otolith (mesial surface). Scale bar5500 Mm.