Cymadusa hallex, 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 : 42-45

Cymadusa hallex sp. nov.

( Figs. 22–24 )

Type material. Holotype, male, 14.5 mm, dissected, 4 slides, WAM C52212, Woodman Point, Western Australia (32°08’S 115°44’E), depth unknown, 20 August 1997, coll. D. Mead-Hunter; paratype female, WAM C52213, Woodman Point (32°08’S 115°44’E), depth unknown, 20 August 1997, coll. D. Mead-Hunter.

Additional material examined. Western Australia: Many specimens, AM P.79446, Bramble Point, Princess Royal Harbour, Albany (35°02’S 117°55’E), in seagrass, January 1988, coll. P.A. Hutchings and party (Site 7); many specimens, AM P.79447, Bramble Point, Princess Royal Harbour, Albany (35°02’S 117°55’E), in seagrass Posidonia simulosa , January 1988, coll. P.A. Hutchings and party (Site 10); 9 specimens, AM P.79448, Bramble Point, Princess Royal Harbour, Albany (35°02’S 117°55’E), in seagrass Posidonia sinuosa , January 1988, coll. P.A. Hutchings and party (site 9); many specimens, AM P.79449, Bramble Point, Princess Royal Harbour, Albany (35°02’S 117°55’E), in seagrass Posidonia sinuosa , January 1988, coll. P.A. Hutchings and party (Site 11); 3 specimens, AM P.79450, Princess Royal Harbour, Bramble Point (35°03’S 117°53’E), in seagrass Posidonia australis , 15 January 1988, coll. P.A. Hutchings, D. Walker and F.E. Wells; 2 specimens, AM P.79452, Quaranup, Princess Royal Harbour, Albany (35°03’S 117°55’E), in seagrass Poisidonia sinnuosa leaves, 14 January 1988, coll. P.A. Hutchings and party (site 3); 1 specimen, AM P.88409, Rockingham Beach (32°16’S 115°44’E), depth unknown, in seagrass Posidonia sp., 1 December 2010, coll. Tina Bell ; 1 specimen, AM P.88410, Rockingham Beach (32°16’S 115°44’E), depth unknown, in seagrass Posidonia sp., 1 December 2010, coll. Tina Bell.

South Australia: 2 specimens (including juvenile male 9.7 mm, dissected, 4 slides), SAMA C6650, 5 km north northwest of Port Davis creek mouth tributary, Port Pirie (33°15’S 137°49’E), seagrass Posidonia sp., March 1980, coll. T. Ward; 3 specimens (2 male, 1 female), SAMA C6390, 5 km north northwest of Port Davis creek mouth tributary, Port Pirie (33°15’S 137°49’E), seagrasses Posidonia sp. and Amphibolus sp., March 1980, coll. T. Ward; 1 male, SAMA C6392, 2.5 km north northwest of 5th creek mouth, Port Pirie (33°15’S 137°49’E), March 1980, coll. T. Ward; 7 specimens (4 male, 3 female), SAMA C6389, Port Pirie, 4 km North northwest of 5th creek mouth, Port Pirie (33°15’S 137°49’E), seagrasses Posidonia sp. and Amphibolus sp., September 1979, coll. T. Ward; 3 specimens (2 male, 1 female), SAMA C 6388, 300 m south of almost exposed reef, approximately 1 km north of sand bar, Franklin Island, Nuyts Archipelago (32°30’S 133°17’E), large rock outcrops and some sand patches, 23 February 1983, coll. W. Zeidler, P. Aerfeldt and party; 1 male, SAMA C6391, 5 km North northwest of 5th creek mouth, Port Pirie (33°15’S 137°49’E), seagrasses Posidonia sp. and Amphibolus sp., September 1979, coll. T. Ward; 4 specimens (1 male and 3 females), SAMA C6663, mouth of 5th creek near Port Pirie (33°15’S 137°49’E), intertidal, August 1979, coll. T. Ward; 1 male, SAMA C6386, 2 km north of 1st creek mouth near Port Pirie (33°15’S 137°49’E), seagrass Posidonia sp., March 1980, coll. T. Ward.

Type locality. Woodman Point, Western Australia (32°08’S 115°44’E).

Etymology. From the Latin hallex , great toe, for the proximal projection of the gnathopod 2 propodus, applied as a noun in apposition.

Diagnosis. Antenna 1 peduncle article 1 with 3 robust setae along posterior margin; accessory flagellum 3- articulate. Mandible accessory setal row with 7 setae. Maxilla 1 inner plate with 6 slender setae; outer plate palp with 8 robust setae. Gnathopod 1 coxa subequal to coxa 2, anterior margin concave, anteroventral corner produced, subacute; basis longer than coxa, anterodistal corner subquadrate; ischium anterior margin without well-developed lobes; propodus subtriangular, palm subacute convex, palm defining corner rounded with 1 robust seta. Gnathopod 2 basis longer than coxa, anterodistal lobe weakly rounded, not reaching beyond ischium, with 2 slender setae; ischium and merus anterior margin without lobes; carpus subtriangular, 0.3 times propodus length, anterior margin with slender setae; propodus subrectangular, length 2.6 times width, palm extremely acute, entire, distal palmar tooth subquadrate (apically crenulate), posterodistal corner with accessory flap of tegument, without palm defining robust setae, palm length 0.8 times posterior margin; dactylus much shorter than palm, tapering evenly, apically acute, with unguis, inner margin smooth. Telson subtriangular, apically rounded, without apical cusps, 4 pair of lateral setae and 2 pair of apical setae.

Description of holotype. Head. Antenna 1 article 1 length 1.1 times article 2, with 3 robust setae along posterior margin; article 3 length 0.35 times article 1; primary flagellum incomplete, with more than 37 articles; accessory flagellum 3-articulate. Antenna 2 incomplete, unknown. Lower lip outer plates slit; lateral distinctly longer than medial lobe, with single pair of apical ducts; mandibular lobes with curved margins, subacute apically.

Mandible accessory setal row with 7 setae; palp slender, 3-articulate; article 2 with 2 slender setae; article 3 length 3.3 times width. Maxilla 1 inner plate with 6 slender setae; outer plate palp article 2 with 8 robust setae.

Pereon. Coxae 1–4 longer than broad. Gnathopod 1 smaller than gnathopod 2; coxa 1 subequal to coxa 2, broader than deep, coxa anterior margin concave, anteroventral corner produced, subacute; basis longer than coxa, posterior margin with sparse slender setae, anterodistal corner subquadrate with 2 slender setae; ischium anterior margin without well-developed lobes; merus anterodistal lobe subacute, posterodistal corner subquadrate; carpus subrectangular, length twice breadth, 1.1 times propodus length, anterior margin with slender setae, posterior margin convex; propodus subtriangular, 1.8 times width, palm subacute convex, palm defining corner rounded with 1 robust seta, palm length 0.4 times posterior margin; dactylus subequal in length to palm, apically acute, tapering evenly, inner margin crenate. Gnathopod 2 sexually dimorphic; basis longer than coxa, anterodistal lobe weakly rounded, not reaching beyond ischium, with 2 slender setae; ischium and merus anterior margin without lobes; carpus subtriangular, length 1.2 times width, 0.3 times propodus length, anterior margin with slender setae; propodus subrectangular, length 2.6 times width, palm extremely acute, entire, distal palmar tooth subquadrate (apically crenulate), posterodistal corner with accessory flap of tegument, without palm defining robust setae, palm length 0.8 times posterior margin; dactylus much shorter than palm, tapering evenly, apically acute, with unguis, inner margin smooth.

Pleon. Epimera 1–3 subquadrate, posterior margin straight, posterodistal corner rounded. Uropod 1 long, reaching past uropod 2 rami; peduncle with 9 robust setae, ventral margin with a few slender setae, with large, acute distoventral spine; length 3.2 times width; inner ramus 0.8 times peduncle length, with 6 marginal robust setae; outer ramus slender with 7 marginal robust setae. Uropod 2 peduncle with small subacute distoventral spine, with 4 robust setae; inner ramus longer than outer ramus, with 10 marginal robust setae; outer ramus with 7 marginal robust setae. Uropod 3 peduncle length twice width, 2 times rami length, with 6 marginal robust setae, 2 distal peduncular robust setae and 3 distal slender setae; inner ramus 1.4 times width, with 4 distal robust setae, 2 distal slender setae and 4 lateral robust setae; outer ramus shorter than inner ramus, length subequal to width, without lateral robust setae, 2 large distal recurved robust setae. Telson subtriangular, apically rounded, without apical cusps, 4 pairs of lateral setae, 2 pairs of lateral plumose setae and 2 pairs of apical setae.

Variation. Male juvenile, 9.7 mm, SAMA C6650. Gnathopod 2 propodus palm defined by subacute tooth, without flap of tegument, palm length 0.6 times propodus margin; dactylus closing half way along palm.

Remarks. Cymadusa hallex sp. nov. is unique within the genus based on the elongate propodus with an acute palm on the male gnathopod 2, with the propodus extending to 0.8 times the length of the propodus posterior margin. This weakly calcified, slender and elongate palm is usually more typical of the genera Peramphithoe and Exampithoe . Also distinctive for C. hallexa sp. nov. is the accessory flap of tegument at the end of the palm that folds across the palm margin.

Distribution. Western Australia: Woodman Point; Albany; Rockingham Beach. South Australia: Port Pirie (current study).

Figures

FIGURE 22. Cymadusa hallex sp. nov., holotype male, 14.5 mm, WAM C 52212, Woodman Point, Western Australia.

FIGURE 23. Cymadusa hallex sp. nov., holotype male, 14.5 mm, WAM C 52212, Woodman Point, Western Australia, scales 0.1 mm.

FIGURE 24. Cymadusa hallex sp. nov., juvenile male, 9.7 mm, SAMA C 6650, Port Pirie, South Australia, scales 0.1 mm.