Cymadusa heronensis Peart, 2007

Hughes, L. E. & Lowry, J. K., 2009, Ampithoidae *, Zootaxa 2260 (1), pp. 153-219 : 178-181

Cymadusa heronensis Peart, 2007

( Figs 15 , 16 )

Cymadusa heronensis Peart, 2007a: 13 , figs 8–11.

Material examined. Holotype, male, 4 mm, AM P61906 ( QLD 1343 ); 7 unsexed, AM P75511 ( QLD 1318 ); 8 unsexed, AM P75511 ( QLD 1318 ); 6 unsexed, AM P75512 ( QLD 1326 ); 6 unsexed, AM P75513 ( QLD 1326 ); 3 unsexed, AM P75514 ( QLD 1329 ); many unsexed, AM P76753 ( QLD 1938 ); 2 unsexed, AM P76755 ( QLD 1941 ); 1 unsexed, AM P76754 ( QLD 2006 ).

Type locality. Northern reef flat, Heron Reef, Heron Island, Queensland, Australia (23º27’S 151º55’E), living on Sargassum sp. , 0.5 m .

Description. Based on holotype, male, 4 mm, AM P61906.

Head. Head as long as deep. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2; flagellum 20 articles; accessory flagellum with 1 article. Antenna 2 peduncle not densely setose on ventral margin; article 4 longer than article 5; flagellum 9 articles. Upper lip directed nearly straight down, lateral margins each with midlateral notch. Mandible molar well developed, triturating, accessory setal row with 5 serrate setae; palp 3–articulate, apically setose; article 1 shorter than article 2; article 2 longer than article 3; article 3 longer than article 1. Lower lip outer plates notched, forming a deep distal cleft, lateral lobe distinctly longer than medial lobe; mandibular lobe with curved margins, rounded apically. Maxilla 1 inner plate with 1 seta; palp article 2 broad. Maxilla 2 inner plate narrower than outer plate. Maxilliped outer plate with row of large robust setae along medial margin.

Pereon. Coxae 1–4 deeper than broad. Gnathopod 1 smaller than gnathopod 2; coxa subequal to coxa 2, slightly produced, anterior margin straight, anteroventral corner subacute, with row of slender setae of varying length along ventral margin; basis subequal to coxa in length, anterodistal lobe rounded, with 1 slender seta; merus posterodistal lobe acute; carpus about as long as broad, shorter than propodus, anterior margin with slender setae, posterior margin subacute; propodus broad, subtriangular; palm acute, sinusoidal, with subquadrate posterodistal corner, with 1 robust seta defining palm; dactylus subequal in length to palm, inner margin crenate. Gnathopod 2 coxa with row of slender setae of varying length along ventral margin; basis with sparse slender setae, anterodistal corner with 1 slender seta; merus margin with short, subacute anterodistal lobe; carpus shorter than propodus, cup-shaped; propodus broad, less than 1.5 x as long as broad, subovoid, not produced into an anterodistally setose lobe, anterior margin with fringe of slender setae; palm acute, excavate, with subquadrate posterodistal corner, without defining palm robust seta; dactylus subequal in length to palm, tapering evenly, apically acute, inner margin crenate. Pereopods 3–4 basis narrow; merus subequal in length to carpus. Pereopods 5–7 weakly prehensile. Pereopod 5 without medial slender setae; distal articles broad; propodus slightly expanded distally, with 2 anterodistal striated robust setae; dactylus strongly curved. Pereopod 6 basis posterior margin rounded, with a single marginal robust seta; distal articles slender; propodus slightly expanded distally, with 3 anterodistal striated robust setae; dactylus strongly curved. Pereopod 7 similar to pereopod 6.

Pleon. Epimera 2–3 posteroventral corner narrowly rounded. Uropod 1 peduncle with 7 robust setae, with long fringe of slender setae (greater than 0.5 x length of peduncle), with large, acute distoventral spine; outer ramus with 3 lateral robust setae; inner ramus with 2 lateral robust setae;. Uropod 2 peduncle with 2 robust setae; outer ramus with 2 marginal robust setae; inner ramus with 3 marginal robust setae. Uropod 3 peduncle longer than broad, less than 2 x length of rami, without marginal slender setae, with 3 distal robust setae, with 5 distal slender setae; outer ramus with 2 weakly curved distal robust setae, without lateral robust or slender setae; inner ramus with 5 distal slender setae, without lateral robust setae. Telson subtrapezoidal, apically truncated, with small apical cusp on each distolateral corner, with 2 pair of apical slender setae and with 2 pair of lateral and 1 pair of apical plumose setae.

Female (sexually dimorphic characters). Based on paratype, female, 4 mm, AM P61907. Gnathopod 1 subequal in size to gnathopod 2; basis subequal in length to coxa, anterodistal lobe absent; carpus posterior margin convex; propodus subovoid; palm convex, with rounded corner. Gnathopod 2 palm sinusoidal, with 1 robust seta defining palm .

Habitat. Brown algae Dictyota sp. , Padina sp. , Sargassum sp. and Green alga Caulerpa sp.

Remarks. Cymadusa heronensis is very similar to C. aungtonyae Peart, 2002 from Thailand and C. thagaay Peart, 2007a from the northern end of the GBR. Cymadusa aungtonyae can be differentiated by mandibular palp article two which has a dense cluster of setae, absent in the two GBR species. Cymadusa heronensis and C. thagaay are also similar to C. mauritiensis (Ledoyer, 1978) though the later species has less setae along the male gnathopod 2 carpus and propodus anterior margin. The lateral cephalic lobe in C. heronensis and C. thagaay is rounded while in C. mauritiensis it is truncate.

The more heavily calcified broadly rounded propodus shape and absence of the distal robust setae on the palm of male gnathopod 2 distinguishes C. heronensis from C. thagaay which has gnathopod 2 propodus margins straight and palm with a distal robust seta.

Distribution. Australia. Queensland: Heron Island ( Peart 2007a, current study); One Tree Island (current study).

Figures

FIGURE 15. Cymadusa heronensis Peart 2007a, holotype, male, 4 mm, AM P61906, Heron Island, Great Barrier Reef (based on Peart 2007a).

FIGURE 16. Cymadusa heronensis Peart 2007a, holotype, male, 4 mm, AM P61906, paratype, female, 4 mm, AM P61907, Heron Island, Great Barrier Reef (based on Peart 2007a).