Sympterichthys unipennis (Cuvier)

Last, Peter R. & Gledhill Csiro, Daniel C., 2009, A revision of the Australian handfishes (Lophiiformes: Brachionichthyidae), with descriptions of three new genera and nine new species 2252, Zootaxa 2252 (1), pp. 1-77 : 55-58

Sympterichthys unipennis (Cuvier)

Figs 4 , 20, 22; Tables 5, 7–10

Lophius laevis Lacepède, 1804: 202 , 210, pl. 55 (4) [original description, junior homonym of Lophius laevis Latrielle, 1804 ]; holotype MNHN A 4630 ; probably Tasmania (as Australian seas).

Chironectes unipennis Cuvier, 1817: 435 [replacement name for Lophius laevis Lacepède , preoccupied].

Chironectes unipinnis Cuvier, 1817 : pl.18 (3) [misspelling of Chironectes unipennis in plate].

Chironectes laevis (non Latrielle). Valenciennes, 1837: 434 [new combination].

Brachionichthys laevis (non Latrielle). Günther, 1861: 182 [new combination].

Sympterichthys laevis (non Latrielle). Gill, 1878: 221 [new combination].

Sympterichthys unipennis . Whitley, 1949: 403 [new combination].

Brachionichthys unipennis . Pietsch, 1985: 95 [new combination].

Sympertichthys laevis (non Latrielle). Paxton et al., 1989: 276 [misspelling of Sympterichthys laevis ].

Holotype. MNHN A 4630 , 43.8 mm SL, Australian seas, voyage de Péron 1800–1804, no other data.

Diagnosis. Member of the genus Sympterichthys with a combination of the following characters: esca minute, as a simple filament (possibly damaged); illicium thick based, thin distally, without dermal spinules, length about 18% SL, 2.7 times in head length; body entirely covered with close-set, embedded, nonimbricate, spiny scales; scale bases variable in shape, dendritic to narrowly thallate, with long unicuspid or bifurcate spinules (except for those closely associated with pores of the acoustico-lateralis system); spinules adpressed, posteriorly directed, originating from posterior region of scale base, apical spines moderately divergent; second dorsal-fin rays 17, fin base 64% SL; length of second dorsal-fin spine 1.3 times length of longest ray of second dorsal fin; 9 anal-fin rays; 9 pectoral-fin rays; fresh coloration unknown, pale in preservative with darker markings on first dorsal fin and membranes of pectoral, pelvic and caudal fins.

Description. D1 2; D2 17; A 9; Pc 9; Pv i, 4; C 1 + 7 + 1 = 9; Vt 9 + 13 = 22.

Body moderately elongate, very strongly compressed, narrowly expanded anteriorly, tail moderately elongate; upper anterior profile convex (pre-illicial snout almost vertical, slightly concave), only slightly elevated before eyes with a prominent supraocular and postocular shelf and deep notch above posterior aspect of eye; upper margin of eye close to dorsal margin of head; nape not humped, not elevated before second dorsal fin; head narrowly oval when viewed anteriorly; anterior ventral profile strongly convex, abdomen bulging; caudal peduncle very short, almost absent, 1.9% SL. Head length 49% SL; snout very short, 7.0 in head; eye 9.2 times in head length; gill opening aperture small, tubiform, subequal to size of pupil, located slightly above and behind insertion of pectoral fin. Nostrils minute and obscure. Mouth small, terminal, moderately protractile; upper jaw slightly oblique, of moderate size, 3.6 in head; upper lip narrow, slightly fleshy; lower lip continuous, connected at symphysis, covered with a fleshy fold laterally that narrows towards junction with upper jaw; jaw angle partly retracting into a thick, vertical skin fold (beneath anterior margin of eye); tongue well developed, rounded. Teeth in upper jaw moderately elongate, caniniform, in about 2 rows; single band of strongly recurved, longer canines in lower jaw; vomer not examined in holotype.

Skin thick, moveable, smooth or wrinkled slightly (not flabby); fully covered with small, spiny scales; scales reasonably closely set, non-imbricated, irregularly spaced, not in defined rows, distributed over entire body, more or less uniform in size; chin and snout tip naked; spinules distributed over rays and membranes of dorsal and anal fins, densest near fin bases; spinules also present on basal half of pectoral, pelvic and caudal fin; fins otherwise naked; illicium naked; scales of acoustico-lateralis system widely separated and indistinct, suboval with short apical spinules, central pore usually not obvious; scale bases embedded, distal apices emergent as low, unicuspid or bicuspid spinules; spinule tips very slender, exposed distally but strongly adpressed, not concealed within wart-like mounds of skin; scale bases very variable in shape, somewhat dendritic or narrowly thallate with 1–4 anterior root-like projections, each about subequal in length to spinule tips; spinules usually recurved upwards, directed posterolaterally (posterodorsally or posteroventrally near dorsal and ventral margins respectively); no enlarged membranous flaps present on arm-like base of pectoralfin; no cutaneous flaps on body.

Illicium terminal, originating at about level of mid-eye, separated by eye diameter from snout tip, preillicial distance 5.5% SL; not elongate, 2.7 in head, 1.3 in length of second dorsal-fin spine, not retractable into a shallow groove beside first dorsal fin; apex possibly damaged, terminating in a minute, curled filament, without an obvious esca, reaching well beyond base of third dorsal-fin spine when depressed; basal third of illicium broad, covered with thick, smooth skin; almost filamentous distally with smooth membrane.

First dorsal fin moderately elevated; second dorsal-fin spine recurved slightly, origin connected to the base of illicium at about a fifth its length, distinctly longer than third spine; membrane of fin plunging toward dorsal surface above pelvic-fin base, then continuing to second dorsal fin as a prominent fleshy ridge; first dorsal-fin base 3.5 in second dorsal-fin base. Second dorsal-fin base moderately elongate, 64% SL, membrane thickest basally, barely concealing ray bases, rays relatively low, simple, those on anterior half barely shorter than those posteriorly. Anal fin moderately elongate, first and last rays shortest, other rays similar in length; longest ray of second dorsal fin 1.3 in longest dorsal-fin spine; anal-fin base 1.8 in second dorsal-fin base. Pectoral-fin base thickened and moderately elongate, extending to about an eye diameter behind gill opening; fin rays slender; fin membranes deeply incised, increasingly so posteriorly; ray tips finger like, flexible, slightly flattened, curved distally. Pelvic-fin moderate to short, located on ventral surface, base almost orientated horizontally; rays slender, rather deeply incised; spine short, embedded and indistinct; interpelvic space flattened, relatively narrow, 7.5% SL. Caudal fin moderately elongate, length 3.3 times caudal peduncle depth; posterior margin damaged, probably emarginate or rounded, weakly incised.

Coloration. In preservative: Body uniformly yellowish white, evidence of darker reddish-brown areas below and above eyes, and on membranes of pectoral, pelvic and caudal fins; apices of first dorsal fin and anterior rays of second dorsal fin reddish brown; no evidence of vertical dark markings through base and posterior margin of caudal fin; membranes of dorsal and caudal fins translucent; eye bluish black. Its coloration after almost two decades in preservative was described by Cuvier (1817) as reddish brown mottled with darker brown.

Size. Known only from the holotype, probably a small species, about 44 mm SL (ca. 58 mm TL).

Distribution. Known only from the holotype and collection data were given as ‘Australian seas’ with no other information. The specimen was obtained by French zoologist François Péron during an expeditionary voyage to Australia in the early 19 th century commissioned by Napoleon Bonaparte and led by Captain Nicolas Baudin (1800–04). During 1802, fish surveys were made in D’Entrecasteaux Channel, southeastern Tasmania. The captain’s journal (see Cornell, 1974, p 310) refers to a little fish ‘which is unusual in that its foremost fins are exactly like hands’. However, Brachionichthys hirsutus (as Lophius hirsutus ) was also taken on the same expedition, and we cannot be certain whether Baudin was referring to one or both of these species. Interestingly, both species are illustrated on plate 55 ( Lacepède, 1804) together with one other fish, Urolophus cruciatus (as Raja cruciata ), which is the most abundant batoid in the D’Entrecasteaux Channel.

Etymology. Epithet based on a combination of the Latin unus (one) and penna (wing), presumably in allusion to its wing-like first dorsal fin. Proposed vernacular name: Smooth Handfish (Yearsley et al., 2006).

Comparisons. Sympterichthys unipennis differs from S. moultoni in several morphometric characters, including having: more slender tail (depth at anal-fin origin 20 vs. 21–24% SL, at second dorsal-fin origin 37 vs. 41–47% SL); a narrower body (maximum width 13 vs. 19–29 % SL, although the S. unipennis holotype has possibly been flattened laterally); and a longer anal-fin base (length 36 vs. 29–33% SL), second dorsal-fin spine (length 24 vs. 17–23% SL), and third dorsal-fin spine (length 22 vs. 15–17% SL). It also has more fin elements (second dorsal-fin rays 17 vs. 15–16; anal-fin rays 9 vs. 7–8; and pectoral-fin rays 9 vs. 7–8).

Remarks. The holotype and only known specimen of Sympterichthys unipennis is in reasonably good condition considering its long preservation period (ca. 200 years). It appears to have undergone minor shrinkage (the supraorbital bones are protruding slightly and the skin is slightly flabby) and its body is strongly compressed indicating that it may have been squashed slightly after capture. Cuvier’s (1817) drawing of this specimen closely resembles the current shape of the holotype (see Fig. 22 ). However, Lacepède’s (1804) original drawing portrays a much deeper bodied fish. Even extreme shrinkage could not account for these differences. As was often the case, the 19 th C drawings appear to have been stylized somewhat, as the caudal peduncle lengths are clearly inaccurate (i.e. much too long) in both cases. We conclude that its present strongly compressed body form is natural rather than artificial.

The shape of the illicium and esca is an important character in most lophiiform fishes. The illicium of the holotype of S. unipennis lacks an esca, and its absence is also evident in both 19 th C drawings suggesting that it was either never present or damaged soon after capture. Interestingly, while all other extant handfishes have an esca, this character is relatively poorly developed in its congener, S. moultoni .

The nomenclatural history of this species is intriguing. The invalid use of Lophius laevis Lacepède , a junior primary homonym of an antennariid, and the validity of its replacement name Chironectes unipennis Cuvier , has been discussed succinctly by Pietsch (1985), and Eschmeyer and Fricke (2009). With the erection of his new genus Sympterichthys, Gill (1878) designated S. unipennis as its type species. One of the authors (PL) initially suspected that this species was distinct from Thymichthys (then Sympterichthys ) verrucosus McCulloch & Waite and advised authors of the first Zoological Catalogue of Australia – Fishes ( Paxton et al., 1989) accordingly. More recently, we suspected that Cuvier’s holotype and handfishes referable to T. verrucosus could be conspecific. The senior author had initially examined the holotype of S. unipennis in Paris (1981) in isolation of the considerable Australian material available of S. verrucosus , and later in partial isolation in Australia (kindly couriered to Hobart by G. Duhamel, 2001). However, a thorough examination of all material referable to Thymichthys verrucosus indicated that more than a single morph existed in Australian collections, so in December 2008 the holotype of S. unipennis was once again couriered to Tasmania (by B. Séret) for a brief re-examination. Based on these comparisons, we concluded that S. unipennis is not conspecific with any of the S. verrucosus morphs or any other extant species. Despite being one of the first Australian fishes discovered by science, the type of S. unipennis remains the only known specimen.

Figures

FIGURE 4. Skin morphology of: A. Pezichthys compressus sp. nov., CSIRO H 4447–01, holotype (x50); B. Pezichthys eltanini sp. nov., LACM 11516–1, holotype (x65); C. Pezichthys macropinnis sp. nov., CSIRO H 5317–02, holotype (x40); D. Pezichthys nigrocilium sp. nov., CSIRO H 6154–01, holotype (x40); E. Sympterichthys moultoni sp. nov., CSIRO H 3773–03, holotype (x50); F. Sympterichthys unipennis, MNHN A 4630, holotype (x50). All images orientated as a view of mid-upper body on left side (i.e. anterior part to left).

FIGURE 22. Sympterichthys unipennis, lateral view of MNHN A 4630, holotype, 43.8 mm SL: A. preserved specimen; B. illustration figured as Chironectes unipennis (reproduced from Cuvier 1817); and C. illustration figured as le Lophie lisse (reproduced from Lacepède 1804, image reversed).