Cymadusa mariabyrneae Hughes & Lowry, 2009

Hughes, L. E. & Lowry, J. K., 2009, Ampithoidae *, Zootaxa 2260 (1), pp. 153-219 : 191-194

Cymadusa mariabyrneae Hughes & Lowry sp. nov.

( Figs 23 , 24 )

Type material. Holotype, male, 6.4 mm, 3 slides, AM P76767 outer reef slope, south of One Tree Island (23°30.79’S 152°5.181’E), large sticks of coral rubble, 13.8 m, I. Takeuchi & L.E. Hughes, 28 October 2006 ( QLD 1994 ) . Paratypes: female, 7.0 mm, 3 slides, AM P76768 ( QLD 1994 ) ; 5 unsexed, AM P76769 ( QLD 1994 ) .

Additional material examined. One Tree Island: 2 unsexed, AM P76771 ( QLD 1959); 1 unsexed, AM P76770 ( QLD 1960).

Etymology. Named for Professor Maria Byrne, director of the One Tree Island Research Station.

Type locality. Outer reef slope, south of One Tree Island, Great Barrier Reef, Queensland, Australia (23°30.79’S 152°5.181’E), living on large sticks of coral rubble, 13.8 m .

Description. Based on holotype, male, 6.4 mm, AM P76767.

Head. Head as long as deep. Antenna 1 and 2 missing. Upper lip lateral margins each with midlateral notch. Mandible molar well developed, triturating, accessory setal row with 6 serrate setae; palp 3–articulate, apically setose and marginally setose; article 1 shorter than article 2; article 2 slightly longer than article 3; article 3 longer than article 1. Lower lip outer plates notched, forming a medial excavation, medial and lateral lobes subequal in size; mandibular lobe with curved margins, rounded apically. Maxilla 1 inner plate with 1 seta; palp article 2 broad. Maxilliped outer plate with row of large robust setae along medial margin.

Pereon. Coxae 1–4 deeper than broad. Gnathopod 1 subequal in size to gnathopod 2; coxa distinctly larger than coxa 2, produced, anterior margin concave, anteroventral corner rounded, with a tuft of slender setae in the posteroventral corner; basis anterodistal lobe absent, with 2 slender setae; merus posterodistal lobe subacute; carpus about 2 x as long as broad, subequal in length to propodus, anterior margin with slender setae, posterior margin straight; propodus broad, subtriangular; palm acute, straight, with rounded posterodistal corner, with 1 robust seta defining palm; dactylus subequal in length to palm, tapering evenly, apically acute, inner margin crenate. Gnathopod 2 coxa with a tuft of slender setae in the posteroventral corner; basis without setae, anterodistal corner lobe absent, with 1 slender seta; merus margin with short, subacute anterodistal lobe; carpus shorter than propodus, subtriangular; propodus broad, less than 1.5 x as long as broad, subrectangular, anterior margin with fringe of slender setae; palm acute, excavate, with posterodistal corner subquadrate, without palm defining robust setae; dactylus overreaching palm, tapering evenly, apically acute, inner margin crenate. Pereopods 3–4 basis narrow; merus subequal in length to carpus. Pereopods 5–7 simple. Pereopod 5 without medial slender setae; distal articles slender; propodus not expanded distally, with 1 anterodistal striated robust seta; dactylus slightly curved. Pereopod 6 basis posterior margin straight, with several marginal slender setae; merus distal articles slender; propodus slightly expanded distally, with 1 anterodistal striated robust seta; dactylus slightly curved. Pereopod 7 similar to pereopod 6.

Pleon. Epimera 2–3 posteroventral corner broadly rounded. Uropod 1 peduncle with 9 robust setae, without fringe of slender setae, with large, acute distoventral spine; outer ramus length about 8 x as long as broad, with 8 lateral robust setae; inner ramus with 5 lateral robust setae. Uropod 2 peduncle with 4 robust setae; outer ramus with 8 lateral robust setae; inner ramus with 7 lateral robust setae. Uropod 3 peduncle longer than broad, less than 2 x length of rami, without marginal slender setae, with 7 distal and 1 mid-dorsal peduncular robust setae, without distal slender setae; outer ramus with 2 large recurved distal robust setae, with 2 lateral robust setae and 3 lateral slender setae; inner ramus with 1 distal slender and 3 lateral robust setae. Telson subtrapezoidal, apically truncated, with small apical cusp on each distolateral corner, with2 pair of oblique medial slender setae, with 2 pair of lateral slender setae, 2 pair of lateral and 1 pair of apical plumose setae.

Female (sexually dimorphic characters). Based on paratype, female, 7.0 mm, AM P76768. Gnathopod 1 subequal in size to gnathopod 2; basis slightly shorter than coxa, with 1 slender anterodistal seta; dactylus slightly overreaching palm. Gnathopod 2 basis anterodistal corner with 2 slender setae; palm straight, with 1 robust seta defining palm; dactylus subequal in length to palm .

Habitat. Coral rubble.

Remarks. Cymadusa mariabyrneae sp. nov. is most similar to C. aungtonyae Peart 2002 from Thailand, in the form and setosity of male gnathopod 2 propodus. Coxae 2–3 in C. mariabyrneae however, are more subquadrate than in C. aungtonyae . The gnathopod 1 palm is straight in C. mariabyrneae and sculptured in C. aungtonyae . Overall the uropods of C. mariabyrneae are more slender with a greater number of robust setae relative to those of C. aungtonyae .

Cymadusa mariabyrneae is superficially similar to the GBR species C. thagaay Peart, 2007a , with respect to the setose anterior margin of the male gnathopod 2. These species differ in two male gnathopod 1 characters: the anterior margin of the coxa which is concave in C. mariabyrneae and straight in C. thagaay ; and the propodus palm which is straight in C. mariabyrneae and sinusoidal in C. thagaay .

Distribution. Australia. Queensland: One Tree Island (current study).

Figures

FIGURE 23. Cymadusa mariabyrneae Hughes & Lowry sp. nov., holotype, male, 6.4 mm, AM P76767, One Tree Island, Great Barrier Reef.

FIGURE 24. Cymadusa mariabyrneae Hughes & Lowry sp. nov., holotype, male, 6.4 mm, AM P76767, paratype, female, 7.0 mm, AM P76768, One Tree Island, Great Barrier Reef.