Macrobrachium rosenbergii ( de Man, 1879 )

Wowor, Daisy & Ng, Peter K. L., 2007, The Giant Freshwater Prawns Of The Macrobrachium Rosenbergii Species Group (Crustacea: Decapoda: Caridea: Palaemonidae), Raffles Bulletin of Zoology 55 (2), pp. 321-336 : 324-326

Macrobrachium rosenbergii ( de Man, 1879)

( Figs. 3 , 5A , 6A–B , 7A , 8 , 10 )

Palaemon Rosenbergii de Man, 1879: 167 .

Palaemon carcinus – von Martens, 1868: 34 (part); de Man, 1879: 165 (part); Miers, 1880: 382 (part); Thallwitz, 1892: 7, 15; Schenkel, 1902: 504; Cowles, 1914: 3, Pl. 1, Fig. 1 (not Cancer carcinus Linnaeus, 1758 ).

Palaemon carcinus var. rosenbergii – Ortmann, 1891: 701.

Palaemon (Eupalaemon) carcinus – de Man, 1892: 421 (part); 1902: 475, 763 (part); Nobili, 1899: 236; Roux, 1928: 219 (not Cancer carcinus Linnaeus, 1758 ).

Palaemon (Eupalaemon) Rosenbergi – Nobili, 1899: 236.

Palaemon spinipes Schenkel, 1902: 501 , Pl. 9, Fig. 7 (not Palaemon spinipes Desmarest, 1817 ).

Palaemon (Eupalaemon) carcinus var. rosenbergi – Roux, 1917: 595; 1921: 587; 1923: 4; 1927: 321; 1933: 344.

Macrobrachium rosenbergii – Holthuis, 1950: 111, Fig. 25 (part); Johnson, 1960: 261 (part); Hedgecock et al., 1979: 873 (part); Lindenfelser, 1984: 195 (part); Chace & Bruce, 1993: 36, Fig. 15; Mather & de Bruyn, 2003: 4 (part); de Bruyn et al., 2004a: 251 (part); 2004b: 3515; Short, 2004: 44, Figs. 16–18, 36L, M; Chand et al., 2005: 308.

Macrobrachium rosenbergi (sic) – Riek, 1951: 361, Fig. 12.

Macrobrachium rosenbergii rosenbergii – Johnson, 1973: 277; Holthuis, 1995: 148; 2000: 16, Fig. 2.2 ; Cai & Ng, 2001: 674.

Material examined. – Type material: Palaemon Rosenbergii de Man, 1879 : holotype, ovigerous female (68.0 mm CL) ( RMNH D 1097 ), Andai, New Guinea [Papua], Indonesia, coll. C. B. H. von Rosenberg, 2 Jun.1869, Feb.–May.1870 . Palaemon spinipes Schenkel, 1902 : holotype, male (74.4 mm CL) ( NHMB 10 a), Kema, Celebes [Sulawesi], Indonesia, coll. P. & F. Sarasin , 1901.

Other material – Indonesia: Sulawesi: 1 male (20.5 mm CL) ( RMNH D 6644 ), Cenrana R .; 1 male (90.4 mm CL) ( RMNH D 6347 ), Makassar; Papua : 10 males (16.5–36.0 mm CL), 11 females (10.4–33.9 mm CL), 1 ovigerous female (32.7 mm CL) ( MZB), Ajkwa R ., Timika; 16 males (19.0– 62.2 mm CL), 18 females (29.2–41.2 mm CL), 20 ovigerous females (29.0– 41.3 mm CL) ( MZB), Ajkwa R ., Timika; Bali: 2 males (18.2–62.6 mm CL) ( NHM 1880.6 ); Sumba : 1 male (19.6 mm CL) ( RMNH D 30657), Rende R ., E. Sumba; Halmahera: 1 female (25.0 mm CL) ( USNM 211084 ), Kao Bay . Philippines: 1 male (64.9 mm CL) ( NHM 1872.7 ); Mindanao : 1 male (81.3 mm CL) ( USNM 53871 ), Zamboanga R .; 1 ovigerous female (42.6 mm CL) ( USNM 53868 ), Rio Grande R .; Luzon: 1 male (83.7 mm CL), 2 ovigerous females (42.4–56.2 mm CL) ( USNM), Manila ; 1 male (42.5 mm CL), 1 ovigerous female (43.6 mm CL) ( USNM 54613 ), Manila ; 3 males (22.9–32.4 mm CL) ( USNM 429 ), Manila ; 1 male (75.1 mm CL), 1 female (55.6 mm CL) ( USNM 441 ), Montalban R ., San Mateo, Rizal; 1 male (52.8 mm CL), 1 ovigerous female (42.8 mm CL) ( ZRC 1999.082 ), Southern Luzon ; Panay : 2 males (33.4–70.7 mm CL), 1 female (52.3 mm CL), 3 ovigerous females (57.4–59.0 mm CL) ( USNM), Jaro R .; 1 male (66.4 mm CL) ( USNM 105626 ), Jaro R .; 1 ovigerous female (45.7 mm CL) ( USNM), Jaro R.; 4 ovigerous females (49.2–55.3 mm CL) ( USNM), Jaro R.; 1 male (41.9 mm CL) ( USNM), Iloilo; 1 ovigerous female (52.3 mm CL) ( USNM), Iloilo; Palawan : 2 females (31.9–34.1 mm CL) ( NHM 1894.7.4.1–2); Bohol : 1 male (104.0 mm CL) ( ZRC 2000.2407 ), Loboc R .; Samar: 1 male (75.0 mm CL) ( USCC), Northern Samar . Papua New Guinea: 1 male (64.7 mm CL) ( USNM 170364 ), Fly R .; 1 male (18.2 mm CL) ( AMNH 11339 ), Fly R .; 1 female (39.9 mm CL) ( USNM 141316 ), Lake Kamu R .; 1 female (29.3 mm CL) ( QM W21966), Bersback R . Australia: Northern Territory: 1 male (53.7 mm CL) , 1 female (44.6 mm CL) ( USNM 151033 ), Darwin ; 1 male (53.7 mm CL) ( NHM 1858.97 ), Northern Australian Expedition ; 1 male (41.1 mm CL) ( NTM Cr 005529), Daly R ., Claravale; 8 males (46.3–59.4 mm CL) ( NTM Cr 005849), Coppermine Billabong, Daly R .; 1 female (24.8 mm CL) ( QM W25412), Adelaide R .; 1 male (16.4 mm CL) ( NTM Cr 007395), Jim Jim Ck., Kakadu ; 2 females (11.0– 13.3 mm CL) ( NTM Cr 006792), Blyth R .; 4 males (45.6–64.7 mm CL), 2 females (37.4–41.5 mm CL) ( QM W19663), Roper R .; 1 male (59.6 mm CL) ( AM P42536), McArthur R .; 5 males (45.1–74.0 mm CL) ( AM P42538), Ryans Bend; Queensland : 1 male (13.4 mm CL) ( QM W12614), Gregory R ., Riversleigh Stn.; 1 male (17.5 mm CL) ( QM W15163), Leichardt R ., crossing near Nardoo Stn.; 1 male (55.6 mm CL) ( QM W15311), Norman R ., Normanton; 1 female (42.3 mm CL) ( QM W7251 ), Norman Ck., Normanton Rd .; 1 male (22.5 mm CL) ( QM W6676 ), mouth of Norman R .; 1 male (31.0 mm), 3 females (15.5–46.9 mm CL) ( QM W14937), Walker Ck. near Normanton ; 1 male (45.0 mm CL) ( QM W16398), Lynd R .; 2 males (65.4–71.2 mm CL) ( QM W7892 ), Mt. Molloy ; 1 male (60.4 mm CL) ( QM W5434 ), Spear Ck. near Mt. Molloy ; 1 male (70.3 mm CL) ( QM W3063 ), Rifle Ck. near Mt. Molloy ; 1 male (83.3 mm CL) ( QM W16487), Mitchell R .; 1 female (16.4 mm CL) ( QM W11967), Mitchell R .; 1 female (27.1 mm CL) ( QM W16399), Palmer R .; 1 male (38.4 mm CL) ( QM W24879), Walsh R .; 1 male (35.1 mm CL) ( AMNH 11340 ), Archer R .; 2 females (23.1–24.3 mm CL) ( QM W11976), Archer R .; 2 females (20.6–21.6 mm CL) ( QM W16393), Archer R .; 1 male (65.5 mm CL) ( QM W9714 ), Coconut Ck. north of Aurukun , Cape York ; 1 male (38.3 mm CL) ( QM W12870), Coen R .; 1 male (47.4 mm CL) ( ZRC 1999.627 ), Wenlock R .; 2 males (12.7–21.5 mm CL), 2 females (17.6–20.2 mm CL) ( QM W16848), Wenlock R .; 1 male (38.9 mm CL) ( QM W16622), Wenlock R .; 3 males (27.5–49.2 mm CL), 2 females (31.9–35.0 mm CL) ( QM W16701), Dulhunty R . at telegraph line crossing; 1 female (39.5 mm CL) ( QM W24289), north of Weipa ; 1 male (20.1 mm CL) ( QM W22243), Olive R .; 1 male (45.0 mm CL) ( QM W16397), East Normanby R ., SW of Cooktown ; 1 male (21.1 mm CL), 3 females (19.1–26.3 mm CL) ( QM W16623), Normanby R ., Orange Plain Waterhole; 1 male (34.6 mm CL) ( QM W3993 ), Hann R .; 1 male (71.0 mm CL) ( QM W16621), Hann R ., Peninsula Developmental Rd.; 2 males (23.6–44.4 mm CL), 4 females (25.8–34.4 mm CL) ( QM W22028), McIvor R ., Isabella-McIvor Rd. crossing.

Diagnosis. – Rostrum long when young, relatively shorter with age, basal crest low to moderately low, sinuous. Rostral formula: 2-3/8-14 (mode 12)/6-15 (mode 9). Second pereiopod long, subcylindrical with carpus extending beyond scaphocerite, carpus longer than merus, similar in form, equal in size, covered by large and small spines except dactylus which is covered by pubescence. T4 armed, post T4 with ridge. Preanal carina present. Mobile mesial spine of exopod of uropod smaller than distolateral tooth. Eggs small, numerous.

Description. – Rostrum: Long (1.37–1.45 times CL in young males of 25.4–27.0 mm times CL with tip distinctly extending beyond distal end of scaphocerite), becoming shorter with age (0.59–0.73 times CL in fully adult males of 65 mm times CL and larger, with tip not extending beyond distal end of scaphocerite but extending beyond end of third segment of antennular peduncle); moderately deep, maximum depth slightly more than maximum dorsoventral diameter of cornea; lateral carina well developed, continuing to about proximal half; basal crest low to moderately low, sinuous; teeth above orbit more closely spaced than those on carapace and distal half of rostrum, teeth on distal half of rostrum most widely spread, armed with 8–14 teeth (mode 12) including 1 or 2 apical teeth, 2 or 3 teeth completely postorbital, postorbital teeth on anterior 0.24–0.30 of carapace; ventral carina with 6–15 teeth (mode 9), first tooth located at about proximal one-third or one-fourth.

General cephalon: ocular cornea well developed, 0.10–0.11 times CL (0.15–0.17 times CL in other specimens). Inferior orbital margin moderately produced, generally angular, with postantennular carapace margin concave or straight in developed specimens, sometimes obtuse, slightly angular above and rounded below in younger specimens. Antennal spine sharp, slender, continuing posteriorly as a ridge, situated below lower orbital angle; hepatic spine smaller, situated behind and below antennal spine; branchiostegal suture running from hepatic spine to carapace margin. Carapace spinulate. Ocular beak well developed with expanded lateral tip. Epistome completely bilobed, lobes with blunt rounded margin. Scaphocerite stout, 0.67–0.68 times CL, length 2.76–2.82 times maximum breath, lamina distinctly tapering from broadest point to anterior margin, anterior margin produced forward at inner angle, lateral margin slightly concave, distolateral tooth failing to reach end of lamella. Third maxilliped with ultimate segment reaching beyond antennal peduncle; ultimate shorter than penultimate, 0.75 as long as penultimate; exopod shorter than ischiomerus.

First pereiopods: Slender, exceeding scaphocerite by distal one-third of carpus; fingers about as long as palm; carpus 2.30–2.39 times chela length, 1.32–1.33 times merus length; a row of short stiff setae present along inner margin of ischium and basis.

Second pereiopods: similar in shape, equal in size, long, slender; carpus of cheliped extending beyond end of scaphocerite. Cheliped: large spines and spinules abundant on all segments except dactylus; dactylus thickly covered by pubescence; chela 2.02–2.03 times CL, length 12.37–14.09 times width, outer and inner margins straight, upper and lower margins rounded; palm subcylindrical, about equal to maximum merus width, width 1.02–1.10 times depth, outer and upper margins more densely covered with smaller spines than inner and lower margins, spinules of equal size cover all surfaces; fingers 0.61–0.74 times palm length, not gaping, cutting edges with well-developed teeth, teeth obscured by pubescence, dactylus with 2 large teeth on proximal 0.3, subequally distributed, pollex with 1 large tooth at distal and 2 smaller teeth towards articulation of fingers distributed along proximal one-fifth, teeth unequally distributed along cutting edges; fingers uncinate at tip; carpus 1.07–1.11 times palm length, subcylindrical, length 6.91–7.11 times distal width, 0.64–0.67 times chela length, 1.33 times merus length; merus not inflated, slightly tapered, 1.41–1.46 times ischium length; ischium tapered with a median groove along upper margin, spines and spinules relatively less dense.

Third pereiopods: large spines, spinules and few scattered rather long stiff setae present on all segments; entire dactylus extend beyond scaphocerite; dactylus stout, curved, fringed with dorsolateral setae, ventral carina obsolete; propodus length 12.47–13.77 times longer than wide; 11 ventral spines distributed along length of propodus, 2 distal most spines paired; carpus 0.44–0.48 times propodus length; merus 1.07–1.13 times propodus length, 2.32–2.38 times ischium length.

Fourth pereiopods: entire dactylus extending beyond scaphocerite; large spines, spinules and few scattered rather long stiff setae present on all segments; propodus with 14 ventral spines, 2 distal-most spines paired; merus 2.39–2.52 times ischium length.

Fifth pereiopods: entire dactylus extend beyond scaphocerite; large spines, spinules and few scattered rather long stiff setae present on all segments; 15 ventral spines distributed along length of propodus; merus 0.94–1.07 times as long as propodus, 2.47–2.61 times longer than ischium.

Thoracic sternum: T4 with small triangular median process, posterior submedian plate low with bluntly rounded tips, notch shallow and wide; T8 with moderately separated anterolateral lobes, without median process. Abdomen: smooth, glabrous. Male abdominal sternites: first 2 abdominal sternites each with medium-sized triangular median process, third abdominal sternite without median process. Inter-uropodal sclerite: well developed, elevated as longitudinal preanal carina, carina small, smaller than posterolateral teeth of sixth abdominal somite. Telson: moderate, stout, glabrous, 3.97–4.32 times median width, lateral margins straight, convergent, 2 pairs of dorsal spines present, posterior subventral margin straight with sharp median point, median projection overreaching inner pair of posterior spines. Uropods: with acute distolateral tooth, mobile mesial spine distinctly smaller than distolateral tooth, exopod 1.95–2.04 times longer than broad.

Remarks. – This species was described by de Man (1879) on the basis of a large ovigerous female from Andai, New Guinea [present day Papua, Indonesia]. However, Ortmann (1891) regarded P. rosenbergii as only a variety of Palaemon carcinus Linnaeus, 1758 , as characterized by Fabricius (1798), an action which was subsequently followed by de Man himself (1892). Cowles (1914) later provided a detailed description and figures of specimens from the Philippines as P. carcinus . This name was widely used in the early literature. In his paper, however, Cowles (1914) commented that whilst the Philippine form of P. carcinus closely resembles P. rosenbergii de Man, 1879 , it shows certain distinct and constant differences from the Indian form, which he regarded as the typical form of P. carcinus . The differences he referred to were mainly related to the structure of the rostrum.

Holthuis (1950) also regarded Macrobrachium rosenbergii ( de Man, 1879) as identical with Palaemon carcinus of Fabricius (1798) but used de Man’s name, as P. carcinus sensu Fabricius (1798) was not the same as Cancer carcinus Linnaeus (1758) . Holthuis (1950) elaborated in detail the clear differences between M. carcinus ( Linnaeus, 1758) from West Atlantic and M. rosenbergii ( de Man, 1879) from the Indo-West Pacific region.

Schenkel (1902) described Palaemon spinipes from Kema, Minahassa, northern Sulawesi. According to Holthuis (1995), Schenkel’s species is likely to belong to the eastern subspecies although he did not specifically assign it to either taxon. Subsequently, Cai & Ng (2001) treated P. spinipes under the synonymy of M. rosenbergii in the broad sense. Re-examination of the type specimen shows it is fits well with the characters of M. rosenbergii de Man, 1879 sensu stricto. Therefore, P. spinipes Schenkel, 1902 should be regarded as a synonym of M. rosenbergii .

We have also observed geographic variation within the Australian populations during this study but this was not reported by Hedgecock et al. (1979) and Lindenfelser (1984). Overall, the morphology of the Australian populations is conservative but is clearly different from M. dacqueti from the west of Huxley’s Line. The morphology of the northeastern Australian population is more similar to those from New Guinea and the Philippines, while the northwestern population has a relatively much shorter rostrum and lower rostral formula (8–12 teeth on the dorsal margin and 5–8 teeth on the ventral margin). Short (2004) also noted that the M. rosenbergii of mid-northern Australia exhibited an intermediate form between the northeastern and northwestern Australian population on the basis of the maximum length of the developed ova being 0.6–0.7 mm (New Guinea and Philippines form), 0.9 mm (mid-northern Australia form) to 1.3 mm (northwest Australian form). The status of all Australia populations will need to be dealt with in a separate study using more material from more parts of Australia. For the moment, however, we provisionally consider all Australian populations as M. rosenbergii sensu stricto.

Distribution. – East of Huxley’s Line, from the Philippines including Palawan Island, Lesser Sunda Islands, New Guinea and northern region of Australia.

Figures

Fig. 3. Macrobrachium rosenbergii (de Man, 1879): A, ovigerous female 39.10 mm CL, lateral view (MZB); B, male 83.30 mm CL, close up, carpus of second pereiopod (QM W 16487).

Fig. 5. Carapace: A, Macrobrachium rosenbergii (male 75.0 mm CL, Ajkwa R., Papua, Indonesia, not preserved); B–C, M. dacqueti: B, adult (male 62.60 mm CL, Jaya R., Bukit Sarang area, Bintulu, Sarawak, East Malaysia, Borneo, coll. H. H. Tan (ZRC), 20 Aug.2005; C, young specimen from Serian, Sarawak, East Malaysia, Borneo, not preserved.

Fig. 6. Young individuals: A–B, Macrobrachium rosenbergii: A, 45.0 mm CL, Tambulig, Panguil Bay, Mindanao, Philippines, not preserved; B, Ajkwa R., Papua, Indonesia, not preserved; C, M. dacqueti, Serian, Sarawak, East Malaysia, Borneo, not preserved.

Fig. 7. Abdomen: A, Macrobrachium rosenbergii (male 75.0 mm CL,Ajkwa R., Papua, Indonesia, not preserved); B, Macrobrachium dacqueti (male 62.80 mm CL, Mahakam R., Melak, E. Kalimantan, Indonesia).

Fig. 8. Macrobrachium rosenbergii:A, B, 2 adult males from Ajkwa R., Papua, Indonesia, not preserved; C, 2 ovigerous females from Dinas, the Philippines, not preserved.

Fig. 10. Map of natural distribution of Macrobrachium rosenbergii (on the right side of dash line) and M. dacqueti (on the left side of dash line). Dashed line = distribution border of the two species.

Fig. 1. Scatterplot of MDA scores (first root) for the two supposed subspecies, adults only. Symbols: Macrobrachium rosenbergii rosenbergii females (filled circle), M. r. rosenbergii males (empty circle), M. r. dacqueti females (filled square) and M. r. dacqueti males (empty square). Eigenvalue = 28.709; Wilks’s λ = 0.034; χ2 = 200.095, df = 8, p <0.0001.

Fig. 2. Scatterplot of MDA scores (first root) for the two supposed subspecies, males only. Symbols: Macrobrachium rosenbergii rosenbergii adult males (filled circle), M. r.rosenbergii young males (empty circle), M. r. dacqueti adult males (filled square) and M. r. dacqueti young males (empty square). Eigenvalue = 6.587; Wilks’s λ = 0.132; χ2 = 267.485, df = 8, p <0.0001.