Beaked Skate

Egg capsules of Zearaja chilensis were obtained from individuals kept in captivity and from dead specimens captured in Valparaíso Bay, central Chile. One female under laboratory conditions deposited three pairs of egg capsules in 6 days. The egg capsules of Dipturus trachyderma were obtained from a female captured in Valdivia, south Chile. Fresh egg capsules of both species were golden-brown and thick walled. Size of egg capsules of Z. chilensis ranged from 94 to 144 mm in capsule length and 64 to 76 mm in capsule width. Those of D. trachyderma ranged between 197 and 199 mm in capsule length and 110.0 and 129.0 mm in capsule width. Range and mean values of capsule length and width of egg capsules described in this study were smaller than those reported for the same species in the south-western Atlantic Ocean. This is the first report on egg-laying rate of Z. chilensis and the first description of egg capsules of Z. chilensis and D. trachyderma from the south-eastern Pacific Ocean.

This medium-sized speies of Dipturus (up to at least 118.0 cm TL) is distinguished from its congeners by the following set of characters: when fresh, the dorsal surface of body is plain brownish to greyish, with some lighter small spots randomly distributed dorsally; one red to purple ocellus over center of each pectoral fin; ocelli with well-defined margins, irregular in shape, but often indistinguishable in fixed specimens; ventrally, white to grey with lighter patches over area of gill openings and beneath mouth; area flanking rostral cartilage membranous and slightly translucent and opaque and yellowish when fixed. Further differs by having a relatively broad disc with angular apices, its width 76.4 (75.0; 77.0) % TL; snout relatively short and broad; tail longer in males (42.2 [40.8] % TL) than in female voucher ([38.8] % TL); ventral head length 35.1 (34.2; 37.7) % TL; preorbital snout length 2.4 (2.9; 2.9) times distance between orbits; orbit diameter 0.5 (0.5; 0.6) of inter-orbital width; in males, the dorsal surface of disc and tail with central longitudinal band of dermal denticles extending from anterior margin of rostral cartilage to tail, including anterior margins of dorsal and caudal fins; a thin band of dermal denticles at anterior margins of pectoral fins, extending from anterior fontanelle to front line of alar thorn patches; dorsal surface of disc and tail of females covered with small dermal denticles, except for external margins of pectoral fins, pelvic fins, and area surrounding caudo-central thorns; with orbital thorns; a single nuchal thorn is often absent; both sexes without scapular thorns; a patch of malar thorns only in adult males; alar thorns only in adult males; medial-dorsal and lateral-dorsal thorns may be present in large specimens, especially in large females; small central-caudal thorns mostly arranged in longitudinal pairs in males and females, with two additional longitudinal rows of fine, sharp and posteriorly oriented lateral-caudal thorns may be present in large specimens; ventral sensory pores are small, distinct, black-edged, most abundant on snout and around mouth, scattered over area between gill openings, sparsely spaced on abdominal area and pectoral fins (Ref. 120403).

Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). Eggs have horn-like projections on the shell (Ref. 205).

Oviparous (Ref. 50449). Reported size at hatching and incubation period 17.2 cm TL and 252 days, respectively (Ref. 120403). Eggs have horn-like projections on the shell (Ref. 205). Inhabits sandy and muddy bottoms at depths (Ref. 104541).