Podocerus walkeri Rabindranath, 1972

Hughes, L. E., 2013, Podoceridae of Tropical Australia (Peracarida: Amphipoda), Records of the Australian Museum 65 (1), pp. 1-37 : 29-32

Podocerus walkeri Rabindranath, 1972

Figs 22–23

Platophium laeve Walker, 1904: 295–296 , pl. 7, fig. 51.

Podocerus walkeri Rabindranath, 1972: 299–302 , fig. 1.— Ledoyer, 1979b: 172, fig. 16.

Podocerus sp. Ortiz & Lalana, 1997: 29–113 (in part).

Podocerus sandroruffoi Ortiz & Lalana, 2003: 61–66 , figs 1, 2.

Podocerus andamanensis .—Wongkamhaeng, Darakrai & Pholpunthin, 2009: 16–19, figs 16, 17.

Type locality. Pamban Coast , Gulf of Mannar, India .

Material examined. Australia. Western Australia. Male , dissected, 4.8 mm, 4 slides, AM P.83810, Jackson Island, Cape Leveque (16°25'19"S 123°05'19"E), 7 m, brown algae Sargassum sp., 27 May 2010, coll. J. K. Lowry ( MI WA 1141 ); female, 4.2 mm, dissected, 1 slide, AM P.87623, Jackson Island, Cape Leveque (16°25'19"S 123°05'19"E), 7 m, brown algae Sargassum sp., 27 May 2010, coll. J. K. Lowry ( MI WA 1141 ); male, dissected, 1 slide, AM P.87622, south of Nelson Rocks, Dampier Archipelago (20°26'31"S 116°40'14"E), 5 m, on brown algae Dictyopteris sp., 7 September 1999, coll. P. Morrison ( WA 715 ); male, 4.1 mm, SEM pin mount, AM P.87033, south of Nelson Rocks, Dampier Archipelago (20°26'31"S 116°40'14"E), 5 m, on brown algae Dictyopteris sp., 7 September 1999, coll. P. Morrison ( WA 715 ); 14 specimens, WAM C51670 , south of Nelson Rocks, Dampier Archipelago (20°26'31"S 116°40'14"E), 5 m, on brown algae Dictyopteris sp., 7 September 1999, coll. P. Morrison ( WA 715 ); 2 specimens, AM P. 79831, 500 m offshore at Bush Bay, 30 km south of Carnarvon (25°10’ S 113°39'E), 0.5 m, branching sea grass, 6 January 1984, coll. J. K. Lowry and R. T . Springthorpe ( WA 426 ); 7 specimens, AM P. 79833, 500 m offshore at Bush Bay, 30 km south of Carnarvon (25°10'S 113°39'E), 2 m, airlift, seagrass detritus, 6 January 1984, coll. J. K. Lowry and R. T . Springthorpe ( WA 431 ) .

Northern Territory. 5 specimens (3 males and 2 females), AM P.87624, bommies, north west end, McCluer Island (11°02'S 132°58'E), 6 m, brown algae, top of reef, 16 October 1982, coll. J. K. Lowry ( NT 48 ) ; 2 male specimens, MAGNT Cr 017402, Black Point , Port Essington, Cobourg Peninsula (11°09.0'S 132°08.2'E), 1–2 m, brown algae Sargassum sp. washings, 18 July 1981, coll. A. J. Bruce and J. N. A. Hooper ( CP 10 ) .

Queensland. Male, dissected, 1 slide, AM P.87625, Cockle Bay, Magnetic Island (19°11'S 146°49'E), depth unknown, seagrass: Cymodocea serrulata , Halodule uninervis and Halophila ovalis , coll. D. W. Klumpp & S. N. Kwak, 17 February 1999 to 16 August 2000; many specimens, AM P.80580, Cockle Bay, Magnetic Island (19°11'S 146°49'E), depth unknown, seagrass: Cymodocea serrulata , Halodule uninervis and Halophila ovalis , coll. D. W. Klumpp & S. N. Kwak, 17 February 1999 to 16 August 2000.

New South Wales. Male, dissected, 3 slides, AM P.87626, Carols Wharf , Scotland Island, Broken Bay (33°38'39.66"S 151°17'29.17"E), 0–1 m, fouling material on boat (including brown algae Padina sp., calcareous bryozoans, solitary and colonial ascidians, black sponge), 14 January 2011, coll. L. E. Hughes ( MI NSW 4012 ); male specimen, AM P.87931, end of sand spit, Kurnell, Botany Bay (34°24"S 151°11'E), 10 May 1972, coll. NSW Fisheries .

Diagnosis. Gnathopod 1 coxa subequal to coxa 2. Gnathopod 2 articles lined with clusters of robust setae; propodus palm distal shelf poorly developed, palm lined with two rows of short robust setae, without teeth or sinus. Pereonites 6–7 dorsal carina broad, produced posteriorly, subtriangular, apically subacute. Pleonites 1–2 dorsal carina broad, produced posteriorly, subtriangular, apically subacute.

Description. Based on male, 4.8 mm. AM P.83810. Body cuticle with posterior dorsal carinae, laterally smooth. Head dorsally smooth; rostrum weakly developed, as broad as long; eyes weakly bulging; lateral cephalic lobe subquadrate; anteroventral corner subquadrate. Mandible accessory setal row with 3 setae. Maxilla 1 palp distal margin with 6 robust setae.

Gnathopod 1 coxa subequal to coxa 2, as broad as long, anteroventral corner produced anteriorly, apically subacute; basis 3 times as long as broad, without anterodistal setae; carpus rectolinear, twice as long as broad; propodus subovate, anterior margin with sparse slender setae, palm margin minutely crenulate with 3 robust setae near corner of palm; dactylus posterior margin with serrate teeth, cuticle surface with raised serrations. Gnathopod 2 articles lined with clusters of robust setae; basis twice as long as broad; anterodistal corner with rounded produced lobe with short robust setae; merus posterior margin lined with a few slender and robust setae, with broad produced lobe, lobe as long as broad, apically rounded, with 2 short robust setae; carpus free, distinct from propodus; propodus subovate, length 1.8 times width, anterior margin with clusters of short robust and slender setae, palm acute, weakly convex, 5⁄6 the length of the propodus, distal shelf poorly developed, shelf margin strongly crenulate, palm lined with two rows of short robust setae, without teeth or sinus, palm defining corner with 3 short robust setae; dactylus closing along palm. Pereonites 6–7 dorsal carina broad, produced posteriorly, subtriangular, apically subacute.

Pleonites 1–2 dorsal carina broad, produced posteriorly, subtriangular, apically subacute. Epimera 1–3 posteroventral corner rounded. Urosomite 1 short, twice as long as broad. Uropod 1 biramus; peduncle twice as long as broad, ventromedial spine absent; inner ramus 1.7 times peduncule length, inner ramus 3⁄4 than outer ramus. Uropod 2 biramous; peduncle ventromedial spine absent; outer ramus 3⁄4 length of inner ramus. Uropod 3 uniramus; rami without setae. Telson dorsal lobe with 2 apical setae, lower margin without lateral or apical setae.

Remarks. Material drawn from Indonesia as P. sandroruffoi Ortiz & Lalana, 2003 is placed as a junior synonymy of P. walkeri . Ortiz & Lalana, 2003 provided exhaustive remarks comparing known Podocerus species with their material, however they did not cite Rabindranath, 1972 who described P. walkeri from the Gulf of Mannar or Ledoyer, 1979b, the first reviewer for the species, with material collected in Indonesia. Material illustrated by Wongkamhaeng et al., 2009 as P. andamanensis (Giles, 1890) from Thailand, is also placed in synonymy. Their illustrations agree with P. walkeri . It is important to note the original description and illustrations for P. andamanensis are too limited for this species to be considered identifiable.

It is possible that P. andamanensis is a senior synonym of P. walkeri , as Giles’s illustrations indicate a male specimen with the gnathopod 2 propodus without plumose setae however a redescription of the type material is needed to assess this situation adequately.

The male gnathopod 2 propodus palm lined with short robust setae and without plumose setae is distinct within the genus. Podocerus walkeri can be separated from the subspecies P. walkeri pedonculata as the latter species lacks the uropod 1 and 2 peduncle ventromedial spine, and the dorsal carina appear to be less developed in mature specimens.

There is no significant variation between the original description of P. walkeri and material figured from Australia, Indonesia (Ortiz & Lalana, 2003) and Thailand ( Wongkamhaeng et al., 2009). Material reported here includes specimens from several sites in Western Australia, Northern Territory; Magnetic Island on the Great Barrier Reef, Queensland and 2 specimens from New South Wales in southeastern Australia (see discussion) .

Distribution. Australia. Western Australia: Dampier Archipelago, Carnarvon, Cape Leveque. Northern Territory: McCluer Island, Port Essington. Queensland: Magnetic Island. New South Wales: Broken Bay, Botany Bay. Sri Lanka: ( Walker, 1904). India: Gulf of Mannar ( Rabindranath, 1972). Indonesia: Misool Island, Banda Naira, Bunaken Island, Sulawesi Island, Maluku Island, Strait of Sunda ( Ledoyer, 1979b; Ortiz & Lalana, 1997; 2003). Thailand: Tarai Island, Tan Island, Rab Island ( Wongkamhaeng et al., 2009).

Figures

Figure 22. Podocerus walkeri Rabindranth 1972, male, 4.1 mm, AM P.87033, Jackson Island, Western Australia. SEM photographs: (A) whole animal lateral view (scale 200 µm); (B) whole animal dorsal view (scale 200 µm); (C) head lateral view (scale 100 µm); (D) head dorsal view (scale 100 µm) and (E) gnathopod 2 propodus palm robust setae (scale 100 µm).

Figure 23.Podocerus walkeri Rabindranth 1972, male, 4.8 mm, AM P.83810, and female, 4.2 mm,AM P.87623, Jackson Island, Western Australia (scale 0.1 mm).