Pezichthys eltanini, 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 : 40-43

Pezichthys eltanini sp. nov.

Figs 2 , 4 , 14, 17; Tables 4, 7–10

Holotype. LACM 11516–1 , 30.0 mm SL, ca. 40 km east of Bruny Island , southeastern Tasmania, 43° 26'S, 147° 52'E, ca. 135 m, 5 Jul. 1968.

Paratype. NMV A 4282 , 36.1 mm SL, possibly off Temma , northwestern Tasmania, 41° 14'S, 144° 06'E, 520 m, 19 Oct. 1984 .

Diagnosis. Member of the genus Pezichthys with a combination of the following characters: esca very large, 54–82% of illicium length; illicium short, stout, with or without dermal spinules, its length 21–22% SL, 2.4–2.6 times in head length; head length 5.4–5.5 times snout length; snout length about 10% SL; eye diameter 6.1–7.0 times in head length; maximum width of body 31–39% SL; interorbital broad, width 12– 15% SL; scale bases stellate with short bicuspid spinules (except for those closely associated with pores of the acoustico-lateralis system); dorsal-fin elements and membranes with full or partial coverage of spiny scales; first dorsal-fin base long, length 25–30% SL; second dorsal-fin rays 15–16, fin base 62–63% SL; length of second dorsal-fin spine 0.9–1.5 times length of longest ray of second dorsal fin; anal-fin rays 7–8; body and fins uniformly white.

*Distance from the base of the third dorsal-fin spine to the origin of the second dorsal fin.

Description. D1 2 (2, n=1); D2 15 (16); A 7 (8); Pc 7 (7); Pv i, 4 (I, 4); C 1 (1) + 6 (6) + 2 (2) = 9 (9); Vt 9 (10) + 11 (12) = 20 (22).

Body tadpole-shaped, moderately short (paratype slightly more elongate); bulbous, weakly compressed anteriorly, suboval in cross section; tail compressed; upper anterior profile strongly convex, not abruptly elevated, upper eye well below dorsal margin; suboval when viewed anteriorly; nape very prominently humped (less so in paratype); anterior ventral profile strongly convex (or weakly convex); abdomen not globose; caudal peduncle short, length 3.6 (5.1)% SL. Head length 55 (53)% SL; snout short, 5.4 (5.5) times in head; eye small, 6.1 (7.0) times in head length; gill opening small, aperture slightly smaller than pupil, located directly above and behind insertion of pectoral fin. Nostrils greatly enlarged (less so in paratype), extending from near upper jaw to level of mid-eye; nasal openings often enlarged, protruding slightly; posterior opening posterodorsal to anterior opening, separated slightly from orbit; openings well separated from each other. Mouth small, terminal, slightly protractile; upper jaw oblique, 3.6 (3.5) in head; lips fleshy, not papillose; angle of jaw partly recessing into groove, situated below anterior margin of eye. Teeth caniniform, recurved, relatively large in holotype; mouth not dissected but teeth apparently in 1–2 rows in lower jaw, in a single row in upper jaw; condition of tongue and vomer not examined.

Skin rather thick, covered with small, bifid, spinulose scales; no separate wart-like patches of skin; very small dermal flap present on mid-upper arm of pectoral-fin (absent in paratype); no other obvious dermal flaps on body, distal parts of dorsal-fin spines with very short filaments. Body scales close-set, distributed over entire body; arranged irregularly, or in variably defined, vertical or oblique rows; scale bases embedded slightly, not with raised mound of thickened skin. Spinules mainly upright (slightly more prostrate on belly), very short, well exposed, bifurcating near skin surface; apical spines uniform in size, connected apically by low integument when undamaged, often directed slightly posteriorly; spiny scales around rim of eye; scale bases stellate, their diameter greatly exceeding spinule length; spinules usually arising from near middle of scale base. First dorsal fin almost entirely covered with small spinulose scales; basal half of second dorsal fin deeply embedded in thick fleshy skin, fin almost entirely covered with spiny scales; spinules covering bases of anal, caudal, and pelvic fins; arm of pectoral fin and base of rayed portion spinulose; fin membranes covered with spiny scales often becoming naked distally. Illicium covered with thin skin and scattering of minute spinulose scales (naked in paratype). Scales of acoustico-lateralis system bicuspid; much larger and distinct from main spinules (less obvious in paratype).

Illicium terminal on snout, stout, 2.6 (2.4) times in head, 1.4 (0.9) times in length of first ray of first dorsal fin; apex of esca extending to middle of eye (hind margin in paratype) when illicium depressed; partly recessible into groove on left side of first dorsal fin; esca greatly enlarged, bulbous, 1.8 (1.2) times in length of illicium; esca with multiple, long filamentous branches; illicial base weakly bulbous. First dorsal fin small, firm, not greatly erectile; second dorsal-fin spine almost confluent with base of illicium, longer than third spine; fin membrane thick, greatly expanded basally around each spine, its posterior medial extension short, membrane inserted above pelvic-fin base; anterior rays of both fins strongly recurved; first dorsal-fin base 2.5 (2.1) times in second dorsal-fin base. Second dorsal-fin low, outer membrane weakly incised, notched slightly at about a third of its length, anterior and penultimate posterior rays longest; insertion slightly forward of analfin insertion (well forward in paratype); rays simple; fin base elongate, 62 (63)% SL; longest ray of second dorsal fin 1.5 (0.9) times in longest dorsal-fin spine; basal membrane thick, concealing all but apices of fin rays anteriorly, covering basal half of posterior rays. Anal fin moderate in size, rays thickened, moderately incised; penultimate posterior rays longest; anal-fin base covered in fleshy skin, 2.5 (1.9) times in second dorsal-fin base. Pectoral fin weakly arm-like, radials moderately elongate, extending well beyond gill opening; fin rays thickened, digitiform, membranes incised, tips flexible, flattened slightly. Pelvic fin moderate in size; rays thickened, digitiform, incised; anterior spine short, embedded and indistinct; fin located on ventral surface, directed ventrolaterally, base aligned horizontally; interpelvic space moderate, almost flat. Caudal fin slender, almost truncate or broadly rounded; length 2.8 (3.1) times caudal peduncle depth.

Coloration. In preservative: Uniformly pale yellow on the body and fins; evidence of slightly darker markings on the esca, dorsal-fin filaments, upper distal membranes of pectoral and pelvic fins, and the hind membranes of the second dorsal and anal fins; eye blackish. Paratype uniformly white, no evidence of markings.

Size. To at least 36.1 mm SL (ca. 48 mm TL). Size of newly hatched young and egg capsule diameter unknown.

Distribution. Demersal in Tasmanian waters, the holotype was collected from ca. 40 km East of Bruny Island (43° 26'S, 147° 52'E), southeastern Tasmania in about 135 m (as 73–75 fathoms). The paratype was questionably from off Temma (41° 14'S, 144° 06'E), northwestern Tasmania, at 520 m depth, but may have been collected off eastern Tasmania (see below).

Etymology. Named in honour of the Polar Research Vessel FRV Eltanin, which was used between 1962 and 1979 to survey Antarctic waters and nearby temperate seas. A deepwater handfish, it is known only from the mid continental shelf, and possibly the upper continental slope, off Tasmania. Proposed vernacular name: Eltanin Handfish.

Comparisons. Within the genus Pezichthys , P. eltanini shares with P. compressus a very large esca (a third or more vs. less than a quarter of illicial length) and scales with stellate (rather than subcircular) bases. It differs from similar sized individuals of P. compressus in having: a larger eye (horizontal diameter 7.5–9.1 vs. 6.4–6.6% SL), a longer second dorsal-fin rays (length of longest ray 19–22 vs. 16–18% SL), and a more slender tail (depth at origin of second dorsal fin 35–44 vs. 47–48% SL). It also differs in the following ratios: head length 6.1–7.0 vs. 8.1–8.3 times eye diameter, and illicium length 1.2–1.8 vs. 2.7–2.8 times esca length.

Pezichthys eltanini also differs from P. amplispinus in having: a shorter pelvic fin (length 17–22 vs. 23– 27% SL), caudal peduncle (length 3.6–5.1 vs. 6.8–11% SL), second dorsal-fin spine (length 19–29 vs. 32– 36% SL), and third dorsal-fin spine (length 15–18 vs. 19–26% SL); a longer first dorsal-fin base (25–30 vs. 18–20% SL), maxilla (length 15–16 vs. 12–14% SL), illicium (length 21–22 vs. 16–20% SL), and esca (length 11–18 vs. 3–4% SL); a broader interorbital (width 12–15 vs. 8–11% SL); and a proportionally larger esca (length 54–82 vs. 19–21% of illicium length). It also differs in the following ratios: head length 3.5–3.6 vs. 3.6–4.5 times upper jaw length, length of second dorsal-fin spine 0.9–1.4 vs. 1.7–2.2 times illicium length, illicium length 1.2–1.8 vs. 4.7–5.3 times esca length, length of second dorsal-fin base 2.1–2.5 vs. 2.9–3.4 times first dorsal-fin base, caudal fin length 2.8–3.1 vs. 3.4–4.6 times caudal peduncle depth.

Remarks. There are uncertainties about the collection data for the paratype of this species. The registration details for this specimen (NMV A 4282) were recorded as station 45, FRV Soela voyage 5/84, on October 19 th, 1984. This station is from the continental slope off the west coast of Tasmania in 520–560 m depth; deeper than any other handfish collected and significantly deeper than the holotype which was collected from the continental shelf off Tasmania’s east coast in ~ 135 m. However, no handfish were recorded on the original catch composition sheet but three specimens, which were listed from station 168 (closer to the collection locality of the holotype), were the only specimens listed from the voyage. Two of these specimens are referred to elsewhere in this manuscript; the third has not been located. It is possible that this paratype is the third missing specimen but this cannot be verified.

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).