Cymadusa lituus, 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 : 801-808

Cymadusa lituus sp. nov.

( Figures 47–50 )

Cymadusa grossimana (form II) Ledoyer, 1984. Lowry, 2007, p. 282 (checklist).

Type material

Holotype male, 8 mm, dissected, four slides, AM P.84476, Grand Recif Mbere , New Caledonia (22 ◦ 19.90 ′ S, 166 ◦ 13.24 ′ E), 27 m, red alga Asparagopsis taxiformis , 22 November 1995, coll. J.K. Lowry, (NCL-199) . Paratype female, 9 mm, dissected, one slide, AM P.84477; paratype female specimen, AM P. 84478, same location as holotype .

Type locality

Grand Recif Mbere , New Caledonia (22 ◦ 19.90 ′ S, 166 ◦ 13.24 ′ E) .

Additional material examined

New Caledonia: three specimens, AM P.84479, Recif Ricaudy (22 ◦ 18 ′ 14 ′′ S, 166 ◦ 26 ′ 09 ′′ E), 0.5 m, brown alga Padina sp. , 4 November 1995, coll. A.A. Myers (NCL-19) ; two specimens, AM P.84480, Passe de Boulari , off Recif To (22 ◦ 30 ′ 09 ′′ S, 166 ◦ 26 ′ 26 ′′ E), 13 m, hydroids, 8 November 1995, coll. I. Takeuchi (NCL-50) ; eight specimens, AM P.84481, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 10 m, fine red filamentous alga on fine white sand bottom, 16 November 1995, coll. J.K. Lowry (NCL-110) ; 1 specimen AM P.84482, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 10 m, coral rubble, 16 November 1995, coll. J.K. Lowry (NCL-113) ; 1 specimen AM P.84483, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 11 m, white sands, hydroids and algae, 16 November 1995, coll. I. Takeuchi (NCL-128) ; five specimens, AM P.84484, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 11 m, white sands, hydroids and algae, 16 November 1995, coll. I. Takeuchi (NCL-128) ; three specimens, AM P.84488, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 10 m, green calcareous alga Halimeda sp. and fine red alga, 16 November 1995, coll. J.K. Lowry (NCL-111) ; seven specimens, AM P.84489, midway between Ilot des Goelands and Grand Recif Abore (22 ◦ 24 ′ 06 ′′ S, 166 ◦ 20 ′ 54 ′′ E), 10 m, green calcareous alga Halimeda sp. with small leaves, 16 November 1995, coll. ORSTOM divers (NCL-116) ; two specimens, AM P.84485, Anse Vata , Pointe Bagay (22 ◦ 18 ′ 14 ′′ S, 166 ◦ 26 ′ 09 ′′ E), 0.5 m, brown alga Sargassum sp. , 18 November 1995, coll. I. Takeuchi (NCL-130) .

Loyalty Island : 12 specimens, AM P.84486, north coast of Lifou , Dokin Village (20 ◦ 42 ′ 09 ′′ S, 167 ◦ 09 ′ 54 ′′ E), 8 m, red alga, 28 November 1995, coll. I. Takeuchi (NCL-232); male, one specimen AM P.84487, north coast of Lifou, Dokin Village (20 ◦ 42 ′ 09 ′′ S, 167 ◦ 09 ′ 54 ′′ E), 2 m, red alga, 28 November 1995, coll. I. Takeuchi (NCL- 234); two specimens, AM P.84426, Baie de Santal, Peng coast, Lifou (20 ◦ 54 ′ 34 ′′ S, 167 ◦ 07 ′ 13 ′′ E), 5 m, floating red alga on white sands, 30 November 1995, coll. I. Takeuchi (NCL-243) .

Etymology

‘ Lituus ’ is the latin word for a curved staff or wand, in reference to the male gnathopod 2 propodus shape.

Diagnosis

Antenna 1 subequal to antenna 2; primary flagellum with 25 articles; accessory flagellum minute, scale-like, uni-articulate. Antenna 2 slender, similar to antenna 1; peduncular article 4 longer than article 5. Mandible accessory setal row with eight robust setae. Maxilla 1 inner plate with four plumose setae; outer plate palp welldeveloped, slender; article 2 with six apical robust setae. Gnathopod 1 smaller than gnathopod 2; coxa anterior margin straight, anteroventral corner produced, broadly rounded, ventral margin with a row of small setules; basis subequal in length to coxa, with medial slender setae, anterodistal lobe small, rounded; propodus subovoid, palm subacute, entire, defined by rounded corner with one robust seta, palm 0.5 times posterior margin. Gnathopod 2 basis length subequal to coxa, with sparse slender setae, with single outer anterodistal lobe large, rounded; carpus compressed, cup-shaped; propodus subovoid to subtriangular, length subequal to width, palm transverse, entire, defined by subacute to rounded corner without tooth or robust setae, palm length 0.6 times posterior margin; dactylus closing short of palm. Telson trapezoidal, apically convex, subapical cusps small, with three pairs of long apical slender setae and two pairs of short lateral slender setae.

Description

Based on holotype male, 8 mm, AM P.84476.

Head. Antenna 1 subequal to antenna 2; peduncular article 1 subequal to article 2; article 2 length 3 times article 3; primary flagellum with 25 articles; accessory flagellum minute, scale-like, uni-articulate. Antenna 2 slender, similar to antenna 1; peduncular article 4 longer than article 5; flagellum incomplete, with at least 17 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 eight robust setae; palp tri-articulate; article 2 with one seta; article 3 length 2.4 times width. Lower lip outer plate notched; outer lobe longer than inner lobe; mandibular lobe with curved margins, apically rounded. Maxilla 1 inner plate with four plumose setae; outer plate palp well-developed, slender; article 2 with six apical robust setae. Maxilla 2 inner plate narrow; outer plate broader. Maxilliped outer plate with large robust setae.

Pereon. Coxae 1–4 longer than broad. Gnathopod 1 smaller than gnathopod 2; coxa 1 larger than coxa 2, anterior margin straight, anteroventral corner produced, broadly rounded, ventral margin with a row of small setules; basis subequal in length to coxa, with medial slender setae, anterodistal lobe small, rounded; merus anteroventral lobe small, rounded; carpus subrectangular, length 2.5 times width, subequal to propodus length, anterodistal corner truncated; propodus subovoid, length 1.7 times width, palm subacute, entire, defined by rounded corner with one robust seta, palm 0.5 times posterior margin; dactylus subequal to palm length, apically subacute, tapering evenly, posterior margin denticulate. Gnathopod 2 coxa ventral margin with a row of small setules; basis length subequal to coxa, with sparse slender setae, with single outer posterodistal lobe large, rounded; merus anteroventral margin subacute; carpus compressed, cup-shaped, length 1.1 times width, 0.5 times propodus length; propodus subovoid to subtriangular, length subequal to width, palm transverse, entire, defined by subacute to rounded corner without tooth or robust setae, palm length 0.6 times posterior margin; dactylus closing short of palm, apically acute, tapering evenly, posterior margin denticulate. Pereopods 3–4 basis and merus narrow. Pereopods 5–7 basis with marginal robust setae; merus subrectangular; dactylus recurved.

Pleon. Epimera 1–3 posteroventral corner subquadrate. Uropod 1 long, reaching end of uropod 2 rami; peduncle length 2.6 times width with 11 robust setae, with a few ventral slender setae, length 2.5 times as long as broad, distoventral spine large, acute; inner ramus 0.9 times length of peduncle, longer than outer ramus, with eight marginal robust setae; outer ramus with nine marginal robust setae. Uropod 2 peduncle with six robust setae, with small distoventral spine; inner ramus with nine marginal robust setae, slightly longer than outer ramus; outer ramus with nine marginal robust setae. Uropod 3 peduncle length 1.6 times breadth, with five distal robust setae, length 1.7 times rami; inner ramus with three distal and two lateral robust setae; outer ramus subequal in length to inner ramus, with two weakly recurved distal robust setae, with two lateral slender setae. Telson trapezoidal, apically convex, subapical cusps small, with three pairs of long apical slender setae and two pairs of short lateral slender setae.

Female (sexually dimorphic characters)

Description based on paratype, 9 mm, AM P.84477.

Pereon. Gnathopod 1 subequal to gnathopod 2; propodus palm subsigmoidal. Gnathopod 2 propodus subrectangular, palm subacute, subsigmoidal, defined by small corner and one robust seta.

Remarks

Cymadusa lituus sp. nov. is established for material previously reported as Cymadusa grossimana (form II) by Ledoyer (1984). Cymadusa lituus sp. nov. can be distinguished from C. grossimana sensu stricto by the gnathopod 1 propodus palm sinusoidal and gnathopod 2 propodus palm corner broadly rounded, while in the latter species the palm of gnathopod 1 is convex and the gnathopod 2 propodus palm corner is subquadrate.

The exceptionally broad gnathopod 2 propodus distinguishes Cymadusa lituus sp. nov. from other species of Cymadusa . Hyperadult males of C. imbroglio ; C. khbarnardi Hughes and Lowry, 2009 and C. smilodonta Hughes and Lowry, 2009 also have a broad ovoid propodus. In C. lituus sp. nov. and C. khbarnardi the male gnathopod 2 propodus palm is smooth while C. imbroglio and C. smilodonta are distinguished by the presence of a midpalmar and distal tooth, respectively. In C. lituus sp. nov. the gnathopod 1 carpus is subequal in length to the propodus, which separates it from C. khbarnardi , which has an extremely elongate carpus, which is 1.5 times the propodus length.

Cymadusa lituus sp. nov. is superficially similar to another New Caledonian ampithoid, Ampithoe kulafi in the gnathopod 2 propodus broad and subovate. These species can be differentiated by the uropod 1 peduncle, which has a rounded spine in the latter species.

Distribution

New Caledonia, Loyalty Islands ( Ledoyer 1984).

Figures

Figure 47. Cymadusa lituus sp. nov., holotype male 8 mm, AM P.84476; paratype female 9 mm, AM P.84477, New Caledonia.

Figure 48. Cymadusa lituus sp. nov., holotype male 8 mm, AM P.84476; paratype female 9 mm, AM P.84477, New Caledonia. Antenna 1–2 scale bars 0.5 mm, all other scale bars 0.2 mm.

Figure 49. Cymadusa lituus sp. nov., holotype male 8 mm, AM P.84476; paratype female 9 mm, AM P.84477, New Caledonia. Scale bars 0.5 mm.

Figure 50. Cymadusa lituus sp. nov., holotype male 8 mm, AM P.84476, New Caledonia. Pereopod scales 0.5 mm, all other scales 0.2 mm.