Cymadusa paradisaea, Peart & Hughes, 2013

Peart, R. A. & Hughes, L. E., 2013, Ampithoid amphipods from the South Pacific: Papua New Guinea, French Polynesia and New Caledonia, Journal of Natural History (J. Nat. Hist.) 48 (13 - 14), pp. 739-861 : 808-814

Cymadusa paradisaea sp. nov.

( Figures 51–54 )

Type material

Holotype male, 6 mm, dissected, three slides, AM P.82832, gully in south entrance of Dam Awan, Madang Lagoon (5 ◦ 09 ′ 16 ′′ S, 145 ◦ 49 ′ 52 ′′ E), no depth, rubble and sediment, 22 February 1990, coll. J.D. Thomas (JDT / PNG-57) . Paratype female,

5 mm, dissected, one slide AM P.82833; paratype, male specimen AM P.82834, same location as holotype .

Type locality

Gully in south entrance of Dam Awan, Madang Lagoon, Papua New Guinea (5 ◦ 09 ′ 16 ′′ S, 145 ◦ 49 ′ 52 ′′ E) .

Etymology

The species name is derived from the endemic Riflebirds, which are the national birds of Papua New Guinea. The name is applied in reference to the plumose “feathery” setation on the male gnathopods.

Diagnosis

Antenna 1 longer than antenna 2; primary flagellum with 22 articles; accessory flagellum minute, scale-like, uni-articulate. Antenna 2 slender, similar to antenna 1; peduncular article 4 longer than article 5; flagellum with 18 articles. Mandible accessory setal row with six robust setae. Maxilla 1 inner plate with two plumose setae; outer plate palp well-developed, broad; article 2 with six apical robust setae. Gnathopod 1 smaller than gnathopod 2; coxa anterior margin straight, anteroventral corner produced, rounded, ventral margin line with setules; basis length subequal to coxa, with fringe of slender setae, anterodistal corner subquadrate; propodus subovoid, palm acute, entire, defined by weak rounded corner with one robust seta, palm length 0.5 times posterior margin; dactylus subequal in length to palm. Gnathopod 2 coxa posteroventral corner with a tuft of long slender setae; basis longer than coxa, with fringe of plumose setae, anterodistal corner subquadrate with robust seta; carpus subtriangular, anterior margin with rows of long, plumose setae; propodus subrectangular, anterior margin with rows of long plumose setae, palm subacute, excavate, defined by subquadrate corner with one robust seta, palm length 0.5 times posterior margin; dactylus overreaching palm. Telson trapezoidal, apically convex, with one pair of long apical slender setae and three pairs of short lateral slender setae.

Description

Based male holotype, 6 mm, AM P.82832.

Head. Antenna 1 longer than antenna 2; peduncular article 1 subequal to article 2; article 2 length 2.3 times article 3; article 3 length 0.4 times article 1; primary flagellum with 22 articles; accessory flagellum minute, scale-like, uni-articulate. Antenna 2 slender, similar to antenna 1; peduncular article 4 longer than article 5; flagellum with 18 articles. Epistome and upper lip angle directed nearly straight down, around 90 degrees. Upper lip distally setose. Mandible molar well-developed, triturating; accessory setal row with six robust setae; palp tri-articulate, slender, long; article 2 with single seta; article 3 length 3 times width. Lower lip outer plate notched; inner and outer lobes equal in size; mandibular lobe with curved margins, apically rounded. Maxilla 1 inner plate with two plumose setae; outer plate palp well-developed, broad; article 2 with six apical robust setae. Maxilla 2 inner and outer plates broad. Maxilliped outer plate with large robust setae.

Pereon. Coxae1–4 longer than broad. Gnathopod 1 smaller than gnathopod 2; coxa subequal in length to coxa 2, anterior margin straight, anteroventral corner produced, rounded, ventral margin lined with setules; basis length subequal to coxa, with fringe of slender setae, anterodistal corner subquadrate; merus anteroventral lobe rounded; carpus subrectangular, length 1.9 times width, 0.9 times propodus length; propodus subovoid, length 2 times width, palm acute, entire, defined by weak rounded corner with one robust seta, palm length 0.5 times posterior margin; dactylus subequal in length to palm, apically subacute, tapering evenly, posterior margin denticulate. Gnathopod 2 coxa posteroventral corner with a tuft of long slender setae; basis longer than coxa, with fringe of plumose setae, anterodistal corner subquadrate with robust seta; merus anteroventral lobes produced, subacute; carpus subtriangular, length 1.5 times breadth, 0.8 times propodus length, anterior margin with rows of long, plumose setae; propodus subrectangular, length 1.6 times width, anterior margin with rows of long plumose setae, palm subacute, excavate, defined by subquadrate corner with one robust seta, palm length 0.5 times posterior margin; dactylus overreaching palm, apically acute, tapering evenly, posterior margin denticulate.

Pereopods 3–4 basis and merus narrow. Pereopods 5–7 basis margins with robust setae; merus subrectangular; dactylus recurved.

Pleon. Epimera 1–3 subquadrate, posteroventral corner rounded. Uropod 1 reaching end of uropod 2 rami; peduncle length 2.8 times width with 11 robust setae, setal fringe half-length of peduncle, distoventral spine large, acute; rami 0.85 times length of peduncle; inner ramus subequal to outer ramus, with seven marginal robust setae; outer ramus with seven marginal robust setae. Uropod 2 peduncle with four robust setae, with small distoventral spine; inner ramus slightly longer than outer ramus, with six marginal robust setae; outer ramus with five marginal robust setae. Uropod 3 peduncle 1.9 times longer than broad, length 1.7 times rami length, with seven distal robust setae; inner ramus twice as long as broad, with three distal and two lateral robust setae; outer ramus subequal in length to inner ramus, with two large recurved distal robust setae, with two lateral slender setae. Telson trapezoidal, apically convex, subapical cusps small, with one pair of long apical slender setae and three pairs of short lateral slender setae.

Female (sexually dimorphic characters)

Description based on paratype female, 5 mm, AM P.82833.

Pereon. Gnathopod 1 subequal to gnathopod 2; carpus length 1.8 times width. Gnathopod 2 without densely setose margins; basis shorter than coxa, without plumose setae; carpus length 0.8 times width, 0.9 times propodus length; propodus subovoid, palm entire; dactylus subequal in length to palm.

Remarks

The posterior margin of the basis of male gnathopod 2 with fringe a of plumose setae aligns Cymadusa paradisaea sp. nov. with the C. filosa group, which includes C. imbroglio Rabindranath, 1972 , C. ledoyeri Peart, 2004 , C. vadosa Imbach, 1967 , C. setosa ( Haswell, 1879) and C. tattersalli Peart, 2004 (see Peart 2004). The absence of dense setae along the coxal margins distinguishes C. paradisaea sp. nov. from C. setosa sensu stricto.

Cymadusa paradisaea sp. nov. is most similar to C. tishana Peart, 2007a in the overall form and setation of gnathopods 1 and 2 carpus and propodus. In C. paradisaea sp. nov. the gnathopod 1 propodus palm is convex, but concave in C. tishana . The gnathopod 2 basis of C. paradisaea sp. nov. has a dense setal fringe which is absent in C. tishana .

Cymadusa paradisaea sp. nov. is also similar to C. thagaay Peart, 2007a in the gnathopod 2 propodus with setose anterodistal lobe and palm excavate. In C. paradisaea sp. nov. the gnathopod 2 basis margin has a fringe of setae and the carpus longer.

Habitat

Specimens were found living in rubble and sediment.

Distribution

Papua New Guinea (current study).

Figures

Figure 51. Cymadusa paradisaea sp. nov. holotype male 6 mm, AM P.82832; paratype female 5 mm, AM P.82834, Papua New Guinea. Scale bars 0.2 mm.

Figure 52. Cymadusa paradisaea sp. nov. holotype male 6 mm, AM P.82832; paratype female 5 mm, AM P.82834, Papua New Guinea. Scale bars 0.2 mm.

Figure 53. Cymadusa paradisaea sp. nov. holotype male 6 mm, AM P.82832; paratype female 5 mm, AM P.82834, Papua New Guinea. Scale bars 0.2 mm.

Figure 54. Cymadusa paradisaea sp. nov. holotype male 6 mm, AM P.82832; paratype female 5 mm, AM P.82834, Papua New Guinea. Scale bars 0.2 mm.