Ceradocus oliveri, Appadoo, Chandani & Myers, Alan A., 2006

Appadoo, Chandani & Myers, Alan A., 2006, Melitids (Crustacea: Amphipoda) of the genera Ceradocus and Mallacoota from Rodrigues Island (Indian Ocean), Zootaxa 1370, pp. 1-22 : 10-12

Ceradocus oliveri sp. nov.

Figures 7–9

Type material. HOLOTYPE. Male, 4.1 mm from Passe Ile des fou (19 ° 39.527 ’ S 63 23.752 ’ E), Rodrigues, on reef crest among rhodolite samples, G. Oliver, 12 September 2001, AM P 73603 .

PARATYPES. 1 male, 4.5 mm, AM P 73605 , 1 female, 5.1 mm, AM P 73604 , 1 male, AM P 73606 ; 10 males, 1 female and 4 juveniles same data as holotype. 1 male from Grande Pate (19 ° 39.307 ’S, 63 ° 24.950 ’E), Rodrigues, on dead coral head, 29 September 2001.

Description. Male, 4.1 mm. Head with subocular notch, eyes with discrete ommatidia. Antenna 1 article 2 subequal to article 1; article 3, 0.25 x article 1; accessory flagellum 5 -articulate. Antenna 2, peduncle article 5, 0.8 x article 4; flagellum 8 -articulate. Mandible palp, 3 -articulate, article 1 distally produced, article 2, 3x article 1, article 3, 0.3 x article 2 with distal patch of setae of long slender setae. Gnathopod 1 coxa 1.3 x as long as broad, antero-distal margin produced; basis 2.8 x as long as broad; propodus 1.1 x carpus, 2 x as long as broad, palm oblique. Gnathopod 2 asymmetrical. Gnathopod 2 (small) coxa 1.4 x as broad as long; basis 3 x as long as broad; carpus 1.7 x as long as broad; propodus slender 2.8 x as long as broad, palm oblique, palmar margin with slender setae. Gnathopod 2 (large), coxa 1.1 x as long as broad, basis 2.9 x as long as broad; carpus triangular in shape, propodus robust, 1.4 x as long as broad; palmar margin transverse characterised by three shallow protuberances, and a well-developed protuberance; palmar margin with few short slender setae, postero-distal corner of palmar margin produced; dactylus fitting palm. Pereopod 3, coxa as long as broad, basis 3.6 x as long as broad, propodus 1.5 x carpus, dactylus outer margin weakly toothed. Pereopod 4 similar to pereopod 3. Pereopod 5 coxa bilobed, basis 2.5 x as long as broad, propodus 1.3 x carpus; dactylus margins smooth. Pereopod 6 basis 2.7 x as long as broad, postero-distal margin weakly produced into a lobe, propodus 1.3 x carpus; dactylus slender. Pleonites 1-2 dorsal margin weakly toothed. Pleonite 3, with 9 teeth. Epimera 1-3 with a tooth on distal margin; Epimeron 1 and Epimeron 2, postero-distal corner weakly produced; Epimeron 3 postero-distal margin strongly produced. Urosomite 1 with two dorsal teeth. Uropod 1 peduncle with robust setae on outer margin, outer ramus 1.1 x inner ramus, 0.9 x peduncle. Uropod 2 outer ramus 1.1 x inner ramus, 1.3 x length of peduncle. Uropod 3, rami subequal, lanceolate, 2.3 x peduncle. Telson (see female).

Female. 5.1 mm, same collection site as described for male. Gnathopod 1 coxa 1.4 x as long as broad, antero-distal corner produced; basis 2.8 x as long as broad; propodus 1.1 x length of carpus, 2 x as long as broad, palm oblique. Gnathopod 2 (small) coxa 0.7 x as long as broad; basis 2.3 x as long as broad; carpus 1.4 x as long as broad; propodus 1.9 x as long as broad, 1.75 x length of carpus; palmar margin oblique with a weak excavation on the postero-distal corner. Gnathopod 2 (large) coxa 1.2 x as long as broad; basis 2.4 x as long as broad; carpus triangular, 2.4 x as broad as long; propodus robust, 1.4 x as long as long as broad, palmar margin similar to male. Telson (from female), cleft to 70 % its length, telsonic lobes produced and characterised by robust setae 1.1 x length of telson.

Remarks. The material from Rodrigues resembles C. hawaiensis J. L. Barnard (1955, 1970) in having a transverse and toothed palm in the larger gnathopod 2 and the toothed dactyls of pereopods. However, Ceradocus oliveri differs from C. hawaiensis in epimeron 3, which is not drawn into a point and lacks a serrated posterior margin, while in C. hawaiensis epimeron 3 is drawn out into a point and it has strongly serrated posterior margin. Moreover, in C. hawaiensis uropod 3 rami are more slender and elongate, and the telson has 2–3 as opposed to 3–4 robust setae.

Distribution. Madagascar, Mauritius, Rodrigues, Lizard Island, Hawaii.

Etymology. Named after the Collector, Graham Oliver, from National Museum of

Figures

FIGURE 7. Ceradocus oliveri sp. nov., male holotype, 4.1 mm, Passe Ile des Fou, AM P 73603. Scales: a = 0.4 mm (G 1, G 2 (both), P 3 - P 7), b = 0.1 mm (D 3, D 4), c = 0.1 mm (enlargement of large G 2).

FIGURE 8. Ceradocus oliveri sp. nov., male holotype, 4.1 mm, Passe Ile des Fou, AM P 73603; male paratype, 4.5 mm (Ep), Passe Ile des Fou, AM P 73605; female paratype, 5.1 mm (T), Passe Ile des Fou, AM P 73604. Scales: a = 0.4 mm (U 3), b = 0.5 mm (Hd, Ep), c = 0.5 mm (A 1, A 2), d = 0.2 mm (Md, T), e = 0.2 mm (U 1, U 2).

FIGURE 9. Ceradocus oliveri sp. nov, female paratype, 5.1 mm, Passe Ile des Fou, AM P 73604. Scales: a = 0.4 mm (G 1, lt G 2), b = 0.4 mm (rG 2).