Cymadusa hentyana, Hughes, Lauren E. & Peart, Rachael A., 2013

Hughes, Lauren E. & Peart, Rachael A., 2013, New species and new records of Ampithoidae (Peracarida: Amphipoda) from Australian Waters, Zootaxa 3719 (1), pp. 1-102 : 45-50

Cymadusa hentyana sp. nov.

( Figs. 25–28 )

Type material. Holotype male, 10 mm, dissected, 4 slides, AM P.62557, Henty Reef, Mounts Bay, Victoria, Australia (38°47’S 143°40’30”E), on bryozoan, 18 m, 3 May 1988, coll. R.T. Springthorpe and P.B. Berents; paratype female, 10 mm, dissected, 1 slide, AM P.62558, Henty Reef, Mounts Bay, Victoria (38°47’S 143°40’30”E), on bryozoan, 18 m, 3 May 1988, coll. R.T. Springthorpe and P.B. Berents; paratypes 6 specimens, AM P.69741, Mounts Bay, northwest side of Henty Reef (38°47’S 143°40’30”E), on bryozoan, 3 May 1988, coll. R.T. Springthorpe and P.B. Berents.

Additional material examined. Tasmania: Male, 20.26 mm, dissected, 4 slides, AM P.90110, Bicheno (41°53’S 148°18’E), 30 m, bryozoans and macroalga Macrocystis sp. holdfast, 8 May 1986, coll. R.H. Kuiter (Tas 26); male, 16.0 mm, dissected, 1 slide, AM P.90111, Bicheno (41°53’S 148°18’E), 30 m, bryozoans and macroalga Macrocystis sp. holdfast, 8 May 1986, coll. R.H. Kuiter (Tas 26); 3 specimens (1 male and 2 females), AM P.83630, Bicheno (41°53’S 148°18’E), 30 m, bryozoans and macroalga Macrocystis sp. holdfast, 8 May 1986, coll. R.H. Kuiter (Tas 26).

Type locality. Henty Reef, Mounts Bay, Victoria, Australia (38°47’S 143°40’30”E).

Etymology. Named for the shape of the male gnathopod 2 propodus which is similar to the outline of Henty reef, the type locality.

Diagnosis. Antenna 1 accessory flagellum 4-articulate. Antenna 2 peduncle article 4 subequal in length to article 5. Mandible accessory setal row with 9 robust setae; Maxilla 1 inner plate with 5 slender setae; outer plate palp slender, article 2 with 9 apical robust setae. Gnathopod 1 coxa distinctly larger than coxa 2, anterior margin concave, anteroventral corner broadly rounded; basis posterior margin with fringe of long, slender setae, anterodistal lobe rounded, with 3 slender setae; propodus subovoid, palm acute, straight defined by 1 robust seta, without corner or tooth. Gnathopod 2 basis with fringe of long, slender setae, with single anterodistal lobe large, rounded, reaching beyond ishcium, anterodistal corner with 6 slender setae; carpus subtriangular, 0.8 times propodus length, anterior margin with cluster of short slender setae; propodus subrectangular, weakly produced into setose anterodistally lobe, palm subacute, excavate, defined by corner with 1 robust seta, palm length 0.3 times posterior margin; dactylus subequal in length to palm, apically acute, tapering evenly, inner margin crenate. Telson subtriangular, apically subacute, with row of lateral slender setae and 1 pair of apical slender setae.

Description of holotype. Head. Antenna 1 peduncular article 1 length 1.36 times article 2; article 2 length 3.5 times article 3; article 3 length 0.21 times article 1; primary flagellum with 53 articles, accessory flagellum 4- articulate. Antenna 2 slender, similar to antenna 1; peduncle article 4 subequal in length to article 5, flagellum with 40 articles. Mandible accessory setal row with 9 robust setae; palp 3-articulate; article 2 with 6 slender setae; article 3 length 3 times width. Lower lip outer plates with slit; lateral lobes distinctly longer than medial lobes, with apical ducts; mandibular lobes with curved margins, rounded apically. Maxilla 1 inner plate with 5 plumose setae; outer plate palp slender, article 2 with 9 apical robust setae.

Pereon. Coxae 1–4 longer than broad. Gnathopod 1 smaller than gnathopod 2; coxa 1 distinctly larger than coxa 2, anterior margin concave, anterodistal corner produced, broadly rounded; basis shorter than coxa, posterior margin with fringe of long, slender setae, anterodistal lobe rounded, with 3 slender setae; merus subtriangular, posterodistal corner truncate; carpus subtriangular, length 1.7 times width, 0.8 times propodus length, anterior margin with a few slender setae; propodus subovoid, length 1.72 times width, palm acute, weakly convex defined by 1 robust seta, without corner or tooth, palm length 0.5 times posterior margin; dactylus subequal in length to palm, apically acute, tapering evenly, inner margin crenate. Gnathopod 2 sexually dimorphic; basis longer than coxa with fringe of long, slender setae, with single anterodistal lobe large, rounded, reaching beyond ischium, anterodistal corner with 6 slender setae; merus anterodistal corner subacute; carpus subtriangular, length 1.6 times width, 0.8 times propodus length, anterior margin with cluster of short slender setae; propodus subrectangular, length twice width, weakly produced into setose anterodistal lobe, palm subacute, excavate, defined by corner with 1 robust seta, palm length 0.3 times posterior margin; dactylus subequal in length to palm, apically acute, tapering evenly, inner margin crenate.

Pleon. Epimeron 1 broadly rounded, posterior margin convex, posterodistal corner rounded. Epimera 2–3 broadly rounded, posterior margin concave, posterodistal corner rounded. Uropod 1 reaching end of uropod 2 rami; peduncle with 9 robust setae, setal fringe 2/3 length of peduncle, with large, acute distoventral spine, length 3.8 times width; inner ramus length 0.9 times peduncle length, longer than outer ramus, with 5 marginal robust setae. Uropod 2 peduncle with 4 robust setae, with small distoventral spine; inner ramus longer than outer ramus with 5 marginal robust setae; outer ramus with 5 marginal robust setae. Uropod 3 peduncle length 1.6 times width, peduncle 2.3 times rami length, without marginal robust setae, with 8 distal peduncular robust setae; inner ramus length 1.7 times width, subequal in length to outer ramus, with 7 distal robust setae and 5 distal slender setae; outer ramus with 2 large recurved distal robust setae, patch of small lateral denticles and lateral setal fringe. Telson subtriangular, apically subacute, with small apical cusps, with row of lateral slender setae and 1 pair of apical slender setae.

Female (sexually dimorphic characters). Based on paratype female, 10 mm, AM P.62558. Pereon. Gnathopod 2 carpus length subequal to width, 0.8 times propodus; propodus length 1.9 times width, without setose anterodistal lobe.

Remarks. Cymadusa hentyana sp. nov. has the elongate gnathopod 2 carpus (length 1.6 times width), carpus length subequal to propodus and propodus anterior margin with rows of setae, which aligns with C. mariabyrneae and C. platys sp. nov. Cymadusa hentyana sp. nov. can be distinguished by the gnathopod 1 propodus palm which is acute and subacute in C. mariabyrneae and C. platys sp. nov.

The combination of gnathopod 1 carpus shorter or subequal to propodus and the gnathopod 2 anterior margin densely setose propodus in Cymadusa hentyana , is similar to C. heronensis , C. jubata sp. nov., C. thaagay , C. tishana and C. wistari .

Cymadsa hentyana sp. nov., C. jubata , and C. wistari have a gnathopod 1 coxa with the anteroventral corner produced which distinguishes them from C. heronensis , C. thaagay and C. tishana Peart, 2007 a. The gnathopod 1 carpus anterior margin with few setae separates C. hentyana sp. nov. and C. jubata sp. nov. from C. wistari , with the more elongate carpus distinguishing C. hentyana sp. nov. overall.

Distribution. Australia. Victoria: Mounts Bay (current study). Tasmania: Bicheno (current study).

Figures

FIGURE 25. Cymadusa hentyana sp. nov., holotype male, 10.0 mm, AM P. 62557; paratype female, 10 mm, AM P. 62558, Henty Reef, Mounts Bay, Victoria.

FIGURE 26. Cymadusa hentyana sp. nov., holotype male, 10.0 mm, AM P. 62557; paratype female, 10 mm, AM P. 62558, Henty Reef, Mounts Bay, Victoria, scales 0.5 mm.

FIGURE 27. Cymadusa hentyana sp. nov., holotype male, 10.0 mm, AM P. 62557; paratype female, 10 mm, AM P. 62558, Henty Reef, Mounts Bay, Victoria, scales 0.5 mm.

FIGURE 28. Cymadusa hentyana sp. nov., holotype male, 10.0 mm, AM P. 62557, Henty Reef, Mounts Bay, Victoria, scales 0.5 mm.