Maugean Skate

description

DESCRIPTION. — Disc quadrangular (Figures 4, 5), 1.12 times as broad as long in holotype (1.09 - 1.12 times in paratypes); maximum angle in front of spiracles 71 ° (68 - 72 °); axis of greatest width 62 % (60 - 69 %) of disc length; anterior margin weakly double concave (slightly less pronounced in females), strongly concave anteriorly, straight to weakly convex beside eyes, slightly concave behind level of spiracles in holotype; apex narrowly rounded; free rear tip broadly rounded. Head elongate, preorbital snout length 5.80 (5.71 - 6.69) times orbit length, 3.75 (3.87 - 4.38) times interorbit; preoral snout length 2.20 (2.30 - 2.58) times internarial distance. Snout tip produced, narrowly pointed; no fleshy process at apex. Orbit well developed, diameter 0.65 (0.58 - 0.69) times interorbital distance; eye lateral; deep subocular furrow extending from origin of orbit to spiracle (not evident in some paratypes). Spiracle large, length 1.70 (1.61 - 2.01) in orbit diameter; opening broadly suboval. Nostril subcircular (Figure 6), often distorted or oval in some paratypes; anterior nasal flap expanded slightly; lateral margin of nostril with a well-defined lobe forming a semi-circular

The Maugean Skate, Zearaja maugeana sp. nov. (Rajiformes: Rajidae) — a micro-endemic, Gondwanan relict from Tasmanian estuaries

description

Raja sp. L Last and Stevens, 1994: 339, fig 34.27, pl. 55. Paratypes CSIRO H 1987 – 01, 706 mm TL, mature male, Bathurst Harbour, Australia, 43 ° 21 ′ S, 146 ° 0 8 ′ E, 12 February 1989, G. Edgar; AMS I 40748 – 001, 682 mm TL, mature male, Bathurst Harbour, Australia, 43 ° 21 ′ S, 146 ° 0 8 ′ E, 27 May 1989, G. Edgar; CSIRO H 5544 – 01, 725 mm TL, female, Bathurst Harbour, Australia, 43 ° 22 ′ S, 146 ° 0 9 ′ E, 29 March 1992, J. Stevens & P. Mooney; CSIRO H 3747 – 01, 578 mm TL, female, Macquarie Harbour, Australia, 42 ° 23 ′ S, 145 ° 27 ′ E, 30 July 1994, M. Lewis; CSIRO H 3976 – 01, 571 mm TL, female, CSIRO H 3976 – 02, 770 mm TL, female, Macquarie Harbour, Australia, 42 ° 24 ′ S, 145 ° 30 ′ E, 17 June 1995, M. Lewis & D. Haslam; CSIRO H 4486 – 01, 685 mm TL, adolescent male, Macquarie Harbour, Australia, 42 ° 12 ′ S, 145 ° 18 ′ E, 3 September 1995, B. Zampatti; CSIRO H 4487 – 01, 744 mm TL, female, Macquarie Harbour, Australia, 42 ° 16 ′ S, 145 ° 15 ′ E, 3 September 1995, B. Zampatti.

The Maugean Skate, Zearaja maugeana sp. nov. (Rajiformes: Rajidae) — a micro-endemic, Gondwanan relict from Tasmanian estuaries

description

Z. maugeana Z. nasuta Z. chilensis holotype min max min max min max Total length (mm) 659 571 770 540 850 398 827 Disc width 70.0 66.5 70.5 66.5 77.2 73.9 76.9 Disc length (direct) 62.2 61.0 63.2 56.8 63.4 59.5 63.5 Snout to maximum width 38.8 37.5 41.7 33.4 42.8 39.9 42.3 Snout length (preorbital direct) 20.8 21.3 24.0 14.7 22.0 18.9 22.7 Snout to spiracle 26.0 26.3 29.5 20.2 27.2 23.7 27.3 Head (dorsal length) 27.3 28.0 31.3 22.3 29.2 26.1 28.9 Orbit diameter 3.6 3.4 3.7 3.5 4.4 3.3 3.8 Orbit and spiracle length 5.3 4.8 5.4 5.1 5.9 5.3 5.5 Spiracle length (main pore) 2.1 1.7 2.2 1.6 2.2 1.9 2.6 Distance between orbits 5.5 5.1 6.1 4.9 6.0 6.5 7.0 Distance between spiracles 7.0 7.0 7.5 6.6 7.5 7.1 8.1 Distance-snout to cloaca 59.3 59.0 62.7 54.7 61.9 55.7 62.3 Cloaca to D 1 25.3 23.9 26.5 0.0 0.0 23.2 27.4 Cloaca to D 2 31.8 29.4 32.3 0.0 0.0 29.0 35.0 Cloaca to caudal origin 37.8 34.8 38.6 0.0 0.0 33.5 40.5 Distance-cloaca to caudal-fin tip 41.2 37.7 42.3 37.8 44.6 37.1 45.6 Ventral snout length (pre upper jaw) 20.6 21.3 24.7 15.1 21.7 20.2 22.2 Prenasal length 18.1 18.5 21.2 13.6 19.7 17.6 19.5 Ventral head length (to fifth gill) 36.1 36.6 38.8 31.1 36.9 35.9 37.7 Mouth width 9.6

The Maugean Skate, Zearaja maugeana sp. nov. (Rajiformes: Rajidae) — a micro-endemic, Gondwanan relict from Tasmanian estuaries

diagnosis

Diagnosis A relatively small species of Zearaja with the following combination of characters: granular denticles absent or poorly developed on dorsal surface of pectoral disc, disc width 67 – 71 % TL, 1.09 – 1.12 times its length; pre upper jaw length 20.6 – 24.7 % TL; ventral head length 36.1 – 38.8 % TL; adult clasper relatively short, 23.9 – 26.8 % TL; tail evenly tapering, not robust, height at midlength 1.3 – 1.4 % TL; snout length 3.75 – 4.38 times interorbital width; pre upper jaw length 2.20 – 2.58 times internasal width; orbit diameter 0.58 – 0.69 of interorbital width; total pectoral radials 78 – 85; predorsal vertebrae 85 – 93; teeth in upper jaw 38 – 43.

The Maugean Skate, Zearaja maugeana sp. nov. (Rajiformes: Rajidae) — a micro-endemic, Gondwanan relict from Tasmanian estuaries