Podocerus zeylanicus ( Walker, 1904 )

Hughes, L. E., 2013, Podoceridae of Tropical Australia (Peracarida: Amphipoda), Records of the Australian Museum 65 (1), pp. 1-37 : 32-35

Podocerus zeylanicus ( Walker, 1904)

Figs 24–26

Platophium zeylanicum Walker, 1904: 297 , pl. 8 (53). Podocerus mangarevae ChevreuX, 1908: 521: figs 33–35. Podocerus zeylanicus .— Ruffo, 1969: 71, fig. 24.— Ledoyer,

1986: 940–942, fig. 371.

Type locality. Cheval Paar , Sri Lanka .

Material examined. Western Australia. Male, 4.8 mm, dissected, 3 slides, AM P.87627, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque (16°29.728'S 123°1.768'E), floating brown alga Sargassum sp., 23 May 2010, coll. K. B. Attwood (MI WA 1096); female, 4.3 mm, dissected, 1 slide, AM P.87628, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque (16°29.728'S 123°1.768'E), floating brown alga Sargassum sp., 23 May 2010, coll. K. B. Attwood (MI WA 1096); male, 4.6 mm, SEM pin mount, AM P.85665, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque (16°29.728'S 123°1.768'E), floating brown alga Sargassum sp., 23 May 2010, coll. K. B. Attwood (MI WA 1096); 12 specimens AM P.83813, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque (16°29.728'S 123°1.768'E), floating brown alga Sargassum sp., 23 May 2010, coll. K. B. Attwood (MI WA 1096). 1 specimen, AM P.83811, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque , Buccaneer Archipelago (16°29.728'S 123°1.768'E), 2 m, 26 May 2010, coll. L. E. Hughes (MI WA 1139); many specimens, AM P.83812, Cygnet Bay Pearl Farm inside lines, Cygnet Bay , Cape Leveque , Buccaneer Archipelago (16°29.728'S 123°1.768'E), 0 m, 26 May 2010, coll. K. B. Attwood (MI WA 1140); many specimens, AM P.83914, Cygnet Bay Pearl Farm outside lines, Cygnet Bay , Cape Leveque (16°28.831'S 123°2.264'E), 2 m, 23 May 2010, coll. J. K. Lowry and K. B. Attwood (MI WA 1094); many specimens, AM P.80990, Cygnet Bay , Cape Leveque , Buccaneer Archipelago (16°28'40"S 123°02'06"E), 2 m, off floating rope line, 10 April 2008; many specimens, AM P.80992, Cygnet Bay , Cape Leveque , BuccaneerArchipelago (16°28'39"S 123°02'46"E), 3 m, off pearl shell in panel, 10 April 2008; 2 specimens, AM P.80994, Cygnet Bay , Cape Leveque , BuccaneerArchipelago (16°28'26"S 123°01'42"E), 3 m, off pearl shell in panel, 11 April 2008; many specimens, AM P.80986, Port George IV, Bonaparte Archipelago (15°23'30"S 124°40'54"E), 3 m, off pearl shell in panel, 15 April 2008; 2 specimens (female and juvenile), WAM C49155, Henderson (32°10'S 115°47'E), ship hull scraping, 6 October 2011 ( MV Armoured 3, operating between Henderson and Barrow Island); many specimens, WAM C49230, draft marks, Flying Foam Passage, Dampier Archipelago (20°28'S 116°50'E), ship hull scraping, 4 November 2011, coll. T. Corkill, S. Cameron, & R. Wilks ( IMSS: West Sea 3005, Sample O) .

Diagnosis. Body cuticle dorsally and laterally smooth, with sparse slender setae. Gnathopod 1 coxa subequal to coxa 2, longer than broad, anteroventral corner weakly produced, apically rounded; propodus subovate, with 11 robust setae near corner of palm; carpus indistinct, fused with propodus; propodus palm with one proximal subtriangular tooth, with palm defining tooth and robust seta; dactylus closing short of palm end.

Description. Based on male, 4.8 mm. AM P.87627. Body cuticle dorsally and laterally smooth, with sparse slender setae. Head dorsally smooth; rostrum short, about 1 tenth of head length; eyes greatly bulging; lateral cephalic lobe rounded; anteroventral corner subquadrate. Mandible accessory setal row with 3 setae. Maxilla 1 palp distal margin with 5 robust setae.

Gnathopod 1 coxa subequal to coxa 2, longer than broad, anteroventral corner weakly produced, apically rounded; basis 2.1 times as long as broad, without anterodistal setae; carpus subtriangular, 1.1 times as long as broad; propodus subovate, anterior margin with clusters of long slender setae, palm margin smooth, with 11 robust setae near corner of palm; dactylus posterior margin with serrate teeth, cuticle surface smooth. Gnathopod 2 basis 2.1 times as long as broad, anterodistal corner subquadrate, without setae; merus posterior margin with a few slender setae, distally rounded, without lobe; carpus indistinct, fused with propodus; propodus subovate, length 1.9 times width, anterior margin with clusters of short slender setae, medial surface with dense plumose setae, palm subacute, straight, ⅔ the length of propodus, with broad, well developed distal shelf, shelf margin strongly crenulate, palm with one proXimal subtriangular tooth, with palm defining tooth and robust seta; dactylus closing short of palm end. Pereopods 5–7 similar in size.

Epimera 1–3 rounded. Uropod 1 biramus; peduncle 3 times as long as broad, ventromedial spine absent; inner ramus subequal in length to peduncule; outer ramus about 3⁄4 the length of the inner ramus. Uropod 2 biramous; peduncle ventromedial spine absent; outer ramus 3⁄4 length of inner ramus. Uropod 3 uniramus; ramus with 3 apical setae. Telson dorsal lobe with 2 long and 2 short apical setae, lower margin without lateral or apical setae.

Female (sexually dimorphic characters) based on female, 4.3 mm. AM P.87621. Gnathopod 1 propodus subtriangular to subrectangular, with 2 robust setae near corner of palm. Gnathopod 2 basis 1.6 times long as broad; anterodistal corner with long robust setae; merus posterior margin with broad produced lobe, lobe 1.1 times as broad as long, apically rounded; carpus free, distinct from propodus; propodus length 1.2 times width, palm weakly convex, without distal shelf or teeth, palm defined by corner with 6 robust setae; dactylus closing along palm.

Remarks. Podocerus zeylanicus ( Walker, 1904) was described from Cheval Paar, Sri Lanka. The species has been cited from French Polynesia (Chevreux, 1907 as P. mangarevae ) and tentatively from Madagascar (P.? zeylanicus Ledoyer, 1986 ). Material drawn here agrees with the limited illustrations provided by Walker, where the gnathopod 1 has a distinct coxa shape, the propodus is subovate and setose, the gnathopod 2 has a fused carpus and propodus palm, with 2 weak teeth and the uropod 1 outer ramus is 3⁄4 the length of the inner ramus. The Western Australian material differs in the telson apical lobe that has four setae, while five, two and three setae are figured French Polynesia, Madagascar and Sri Lanka, respectively. This variation in telsonic setation is minor when considered against the consistency in all other species level characters and the wide geographic distribution of material. Material examined from Cape Leveque, Western Australia in 2008 was collected between pearl farming lines, the same habitat as the first documented collection in 1902 from Sri Lanka.

Podocerus zeylanicus has a male gnathopod 2 propodus palm tooth formula common throughout the genus Podocerus , a broad distal shelf with one proximal and one distal tooth, is also known for P. cuspiclunis Horton, 2008 , juvenile P. hanapepe J. L. Barnard, 1970 , P. lobatus ( Haswell, 1885) and P. palinuroides Ledoyer, 1986 .

A smooth dorsum separates P. zeylanicus , P. hanapepe and P. lobatus from P. cuspiclunis , P. lobatus (of Pirlot, 1938) and P. palinuroides . Podocerus zeylanicus , P. cuspiclunis and P. hanapepe are without the cluster of plumose setae on the gnathopod 2 basis seen on P. lobatus (including Pirlot, 1938) and P. palinuroides . Podocerus zeylanicus can be separated from P. hanapepe , P. lobatus and P. cuspiclunis by the lateral cephalic lobe rounded and the male gnathopod 2 basis more elongate. In P. zeylanicus the gnathopod 1 coxa is distinct in shape, as broad as long with the anteroventral corner weakly produced, and the gnathopod 2 propodus palm has numerous, nine or more, robust setae, separating it from other taxa.

Female P. zeylanicus are similar to P. uncinatus Kilgallen, 2009 from the Great Barrier Reef (known only from female specimens). However the coxa in P. zeylanicus are contiguous, with coxa 2 more subquadrate compared with the small discontiguous coxa in P. unicinatus .

Distribution. Sri Lanka. East Cheval Parr ( Walker, 1904). Red Sea: Cundabilu Island ( Ruffo, 1969). French Polynesia. Gambier Archipelago: Magnareva Island. Australia ( Chevreux, 1908). Western Australia: Henderson, Dampier Archipelago, Cape Leveque, Port George IV (current study).

Figures

Figure 24. Podocerus zeylanicus (Walker, 1904), male, 4.6 mm, AM P.85665, Cygnet Bay, Western Australia. SEM photographs: (A) whole animal lateral view (scale 200 µm); (B) whole animal dorsal view (scale 200 µm); (C) gnathopod 2 propodus palm plumose setae (scale 20 µm); (D) head dorsal view (scale 100 µm) and (E) head lateral view (scale 100 µm).

Figure 25. Podocerus zeylanicus (Walker, 1904), male, 4.8 mm, AM P.87627, Cygnet Bay, Western Australia (scale 0.1 mm).

Figure 26. Podocerus zeylanicus (Walker, 1904), male, 4.8 mm, AM P.87627, and female, 4.3 mm, AM P.87628, Cygnet Bay, Western Australia (scale 0.1 mm).