Pezichthys macropinnis, Last & Gledhill Csiro, 2009

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 : 44-46

Pezichthys macropinnis sp. nov.

Figs 2 , 4 , 14, 18; Tables 4, 7–10

Holotype. CSIRO H 5317–02 , 20.5 mm SL, ca. 300 km south-west of Ceduna, Great Australian Bight , South Australia, 33° 16'S, 130° 37'E, 145 m, May 2000.

Diagnosis. Member of the genus Pezichthys with a combination of the following characters: esca small, 12% of illicium length (including esca); illicium very elongate and slender, without dermal spinules, its length about 26% SL, 1.9 times in head length; head length about 5.4 times snout length; snout long, length 9% SL; eye 6.9 times in head length; body robust, maximum width about 32% SL; interorbit broad, width about 15% SL; scales with subcircular bases, monospinulate or with prominent, strongly diverging bifurcate spinules (except for those closely associated with pores of the acoustico-lateralis system); spinules variable in length over body; dorsal-fin elements mostly lacking spinules, membranes of fins naked; first dorsal-fin base about 18% SL; second dorsal-fin rays 15, fin base 63% SL; fin rays very elongate, longest ray of second dorsal fin about 35% SL; length of second dorsal-fin spine 0.9 times length of longest ray of second dorsal fin; anal-fin rays 8; body pale with a network of reddish streaks.

Description. D1 2; D2 15; A 8; Pc 7; Pv i, 4; C 9 (two middle rays branched apically, others simple); Vt 9 + 12 = 21.

Body short, moderately compressed; upper anterior profile weakly convex to first dorsal-fin origin, almost upright; not deeply notched behind eye; top of eye well below top of head; oval when viewed anteriorly; nape humped slightly; anterior ventral profile weakly convex, almost straight between pelvic fins; abdomen barely expanded; caudal peduncle moderately elongate, length 7.6% SL. Head length 49% SL; snout short, 5.4 times in head; eye of moderate size, 6.9 times in head length; gill opening small, aperture much smaller than pupil, located immediately above and behind insertion of pectoral fin; nostrils very small, openings obscure. Mouth small, terminal, slightly protractile; upper jaw slightly oblique, 6.5 in head; lips not fleshy; angle of jaw partly recessing into groove, situated below middle of eye. Teeth minute, villiform, apparently in narrow broad bands in both jaws; mouth not dissected to expose vomer and tongue.

Skin thin, not corrugated, covered with mainly bifid, spinulose scales; no separate wart-like patches of skin; no obvious dermal flap on mid-arm of pectoral-fin; dermal flaps absent on body and other fins. Body scales dense, close-set, not imbricate or arranged in defined rows; distributed over entire body; mostly absent from fin rays and membranes (a few spiny scales near bases of leading rays of both dorsal fins); small, naked patch surrounding gill opening; scale bases large (to about a third of pupil diameter), embedded, but not within a prominent mound of thickened skin. Spinules relatively tall, well exposed, usually bifurcate; semierect, usually directed posteriorly; divergent (length of spines of each spinule subequal to or slightly longer than the distance between their tips), bifurcating just above skin surface; tips not connected by integument when undamaged; on belly smaller and less erect than those above; spiny scales present around rim of orbit. Illicium base and main stem naked, not covered with a sheath-like membrane. Scales of acoustico-lateralis system bicuspid, not obviously distinguishable from main spinules; widely separated and arranged in barely discernable rows; most pronounced near mouth, otherwise indistinct on head and body.

Illicium subterminal on snout, close to upper jaw, its insertion not confluent with origin of first dorsal fin; very long and slender, 1.9 times in head, 1.2 times in length of second dorsal-fin spine; apex of esca behind hind margin of eye when illicium depressed; partly recessible into a groove beside first dorsal fin; esca minute, very narrow, length 9 times in length of illicium, fleshy without filamentous branches; illicial base not bulbous. First dorsal fin short-based; spines very elongate, second dorsal-fin spine separated slightly from base of illicium, much shorter than third spine; fin membrane moderately well developed near fin bases, absent and probably damaged distally; posterior extension of membrane very short, terminating above base of pelvic fin; anterior elements of both fins not or weakly recurved; first dorsal-fin base 3.5 times in second dorsal-fin base. Second dorsal fin very tall (damaged so extent of incision indeterminate), anterior rays longest; rays simple, very fine, their tips not recurved, often damaged; fin base very elongate, 63% SL; longest ray of second dorsal fin 0.9 of longest dorsal-fin spine; bases of rays barely embedded. Anal fin very tall with moderately elongate base, rays delicate, not fleshy, tips not strongly recurved; penultimate posterior rays longest; anal-fin base 2.6 times in second dorsal-fin base. Pectoral fin weakly arm-like, radials elongate, extending well beyond gill opening; fin rays between filamentous and digitiform, slender, membranes not deeply incised. Pelvic fin relative long; rays filamentous, slender, not deeply incised; anterior spine very short, not deeply embedded; fin located on ventral surface, directed ventrally; interpelvic space almost flat, broad, width 14% SL. Caudal fin very elongate, slender; length 4 times caudal peduncle depth.

Coloration. In preservative: White with linear markings on the body; markings reddish, irregular, very fine, concentrated on upper half, becoming more diffuse ventrally. Fins translucent. Eye blackish.

Size. Known only from the holotype, 20.5 mm SL (ca. 29 mm TL). Size of newly hatched young and egg capsule diameter unknown.

Distribution. Demersal, off Ceduna, Great Australian Bight, South Australia (33° 16'S, 130° 37'E), recorded from 145 m depth.

Etymology. Combination of the Greek makros (large) and the Latin pinna (fin) in reference to its tall dorsal and anal fins. Proposed vernacular name: Longfin Handfish.

Comparisons. The unique holotype of this species, which appears to be a juvenile (20.5 mm SL), differs markedly from all other known handfishes. The fine, dark, linear body markings and extremely long illicium (and fin rays and spines), are not found in any other extant brachionichthyid. Despite its smaller size and possibility of some atypical allometric changes, P. macropinnis differs from its congeners in having: a longer pectoral fin (length 27 vs. 19–24% SL in P. compressus , and 22–25% SL in P.eltanini ), illicium (length 26 vs. 16–20% SL in P. amplispinus , 19–23% SL in P. compressus , and 21–22% SL in P. eltanini ), third dorsal-fin spine (length 42 vs. 19–26% SL in P. amplispinus , 16–19% SL in P. compressus , and 15–18% SL in P. eltanini ), and second dorsal-fin rays (length of longest ray 35 vs. 17–25% SL in P. amplispinus , 16–18% SL in P. compressus , and 19–22% SL in P. eltanini ); a shorter pelvic-fin (length 16 vs. 23–27% SL in P. amplispinus , 23–23% SL in P. compressus , and 17–22% SL in P. eltanini ), maxilla (length 7.6% SL vs. 12– 14% SL in P. amplispinus , 15–16% SL in P. compressus , and 15–16% SL in P. eltanini ), and interdorsal distance (distance between bases of third dorsal-fin spine and second dorsal fin 15 vs. 23–28% SL in P. amplispinus , 28–30% SL in P. compressus , and 27–27% SL in P. eltanini ); and a relatively shorter esca (length 12% of illicium length vs. 19–21% in P. amplispinus , 35–36% in P. compressus , and 54–82% in P. eltanini ).

In addition to these characters, P. macropinnis appears to be distinguishable from P. amplispinus in having: longer distance from snout to second dorsal-fin origin (distance 43 vs. 35–42% SL) and pre-illicial distance (5.6 vs. 0.2–1.4% SL); a wider interorbit (width 15 vs. 8.1–11% SL); a relatively longer illicium (54 vs. 33–39% of head length). It also differs in the following ratios: illicium length 8.7 vs. 4.7–5.3 times esca length, and longest dorsal-fin spine 0.9 vs. 1.4–1.9 times length of longest ray of second dorsal fin.

Pezichthys macropinnis appears to be distinguishable from P. compressus in having: a broader interorbit (width 15 vs. 12–13% SL); longer caudal fin (length 40 vs. 33–37% SL) and second dorsal-fin spine (length 33 vs. 24–26% SL); and shorter first dorsal-fin base (length 18 vs. 26–28% SL) and esca (length 3.0 vs. 6.8– 8.0% SL). It also differs in the following ratios: head length 6.5 vs. 3.4–3.6 times upper jaw length, illicium length 8.7 vs. 2.7–2.9 times esca length, longest dorsal-fin spine 0.9 vs. 1.5 times longest ray of second dorsal fin, and caudal-fin length 4.0 vs. 2.8–3.3 times caudal peduncle depth.

In addition to the above characters, P. macropinnis can be distinguished from P. eltanini by: a longer caudal peduncle (length 7.6 vs. 3.6–5.1% SL); a relatively larger illicium (length 53 vs. 38–41% of head length); shorter first dorsal-fin base (length 18 vs. 25–30% SL), head (length 49 vs. 53–55% SL), and esca (length 3.0 vs. 11–18% SL). It also differs in the following ratios: head length 6.5 vs. 3.5–3.6 times upper jaw length, and illicium length 8.7 vs. 1.2–1.8 times esca length.

Remarks. The fossil brachionichthyid, Histionotophorus bassanii (BMNH P 19060), figured by Rosen & Patterson (1969), is similar in general morphology to the juvenile P. macropinnis . Both species have very long fins but differ markedly in most meristic characters. Early juveniles of Brachionichthys australis , B. hirsutus and Thymichthys verrucosus , the only handfishes for which small juveniles are known, closely resemble their adults in body shape. Whitley (1949) made similar observations for B. australis (as B. hirsutus ). Hence, it is likely that the adult of P. macropinnis is also a long-finned form, probably closely resembling the holotype. It has a small esca (about 11% of illicial length) and scales with subcircular (rather than stellate) bases, placing it in a subgroup of Pezichthys along with P. amplispinus and P. nigrocilium .

Figures

FIGURE 2. Illustrations of the illicium and esca of: A. Brachionichthys australis, CSIRO H 4114–07, 55.8 mm SL; B. Brachionichthys hirsutus, CSIRO T 7, 78.9 mm SL; C. Brachiopsilus dianthus sp. nov., CSIRO H 4995–01, holotype, 99.5 mm SL; D. Brachiopsilus dossenus sp. nov., NMV A 29405–002, holotype, 65.0 mm SL; E. Brachiopsilus ziebelli sp. nov., CSIRO T 1993–01, holotype, 101.5 mm SL; F. Pezichthys amplispinus sp. nov., CSIRO H 4460–01, 37.2 mm SL; G. Pezichthys compressus sp. nov., CSIRO H 4447–01, holotype, 42.4 mm SL; H. Pezichthys eltanini sp. nov., LACM 11516–1, holotype, 30.0 mm SL; I. Pezichthys macropinnis sp. nov., CSIRO H 5317–02, holotype, 20.5 mm SL; J. Pezichthys nigrocilium sp. nov., CSIRO H 6154–01, holotype, 40.8 mm SL; K. Sympterichthys moultoni sp. nov., CSIRO H 3773–03, holotype, 45.1 mm SL; L. Thymichthys politus, CSIRO H 782–01, 67.3 mm SL; M. Thymichthys verrucosus (tasselled morph), CSIRO T 5, 51.3 mm SL; and N. Thymichthys verrucosus (eastern form) CSIRO H 3781– 01, 63.5 mm SL.

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).