Amphioplus lucyae Tommasi 1971

Amphioplus lucyae Tommasi, 1971

(Fig. 2)

Amphioplus lucyae Tommasi, 1971: 6, fig. 19–20.— Tommasi et al., 1988: 6.— Borges et al., 2002: 42, fig. 23c–d.— Borges, 2006: 28 –29.— Carranza et al., 2007: 104 –105, fig. 2.

Amphilepis sanmatiensis Bernasconi & d'Agostino, 1975a: 356 –358, fig. 1–3 [new synonymy].

Material examined. SAO II: stn 126, Golfo San Matías, 41° 42´S, 64° 59´W, 20–25 m, 1971, holotype of A. sanmatiensis (MACN 27862). Golfo San José, 42° 20.103´S, 64° 19.9706´W (MACN 28152, n=15).

Comparative material. Amphioplus affinis (Studer, 1885): Bahia Schleiper, 18 m, 11/1929, identified by Bernasconi & d'Agostino (1975b), (MACN 27100, n=2). Base Petrel, 250 m, 1968 (MACN 27685, 1). Amphioplus albidus (Ljungman, 1867) collected 1932 (MACN 26825, 3). La Paloma, 12 m, 1975, MACN 27897. La Paloma, 34° 30´S, 54° 15´W, 2 m, 2/1974, identified by Bernasconi & d'Agostino (1977) (MACN 27863, 3).

Distribution. Brazil (22°S) to Argentina (42°S), 0– 510 m.

Remarks. Bernasconi and d'Agostino (1975a) described a small (2.8 mm d.d.) unique specimen from the Golfo San Matías, Argentina as a new species of Amphilepis, A. sanmatiensis. The additional material of various sizes now available at the MACN indicates that this specimen is in fact a juvenile of the Brazilian species Amphioplus lucyae. This specimen appears to have on each jaw a single apical tooth, flanked by two small rounded papillae, two long narrow papillae near the distal end of the jaw slit, and oral pores placed some distance away from the jaw slit each protected by a minute adoral shield scale (Fig. 2 B). With growth (Fig. 2 D & F), the small flanking papilla moves to the apex of the jaw to become one of the infradental papillae, the distal papilla become the buccal scale (of which only the proximal tip is obvious in ventral view), and the oral pore moves to the base of the jaw slit with the adoral shield papilla becoming the middle of a curved series of three distal oral papillae. On the dorsal disc surface, the primary plates, contiguous in small specimens (Fig. 2 A), gradually separate (Fig. 2 C & E). The dorsal arm plates, as wide as long on small specimens, become twice as wide as long on larger specimens (6 mm d.d.). The ontogeny of the jaw is similar to that described for Amphioplus abditus (Verrill, 1871) by Hendler (1978).

Several other Amphilepis species have been found to represent juvenile Amphiura or Amphioplus species. Bernasconi and d'Agostino (1974) themselves synonymised Amphilepis antarctica Koehler, 1908 with Amphioplus affinis (Studer, 1882) and Madsen (1967) suggested that Amphilepis gymnopora Hertz, 1927 was probably a juvenile of Amphiura belgicae Koehler, 1901. Other Amphilepis species (e.g., A. ingolfi Mortensen, 1933) retain the paedomorphic jaw into maturity.

Thomas (1975) suggested that Amphioplus lucyae may prove to be a synonym of Amphioplus albidus Ljungman, 1867. However, both species occur along the Argentinean coast and are quite distinct. Amphioplus albidus can be distinguished by the small disc scales, the primary plates barely noticeable, 5 arm spines (compared to 4 on A. lucyae), wide oral shields that are twice as wide as long (only as wide as long on A. lucyae), and the presence of a small gap between the middle and distal oral papillae (see Bernasconi & d’Agostino 1977, pl. 5). The new records listed above represent a range extension for A. lucyae to southern Argentina.