Macrobrachium urayang, Wowor & Short, 2007

Wowor, Daisy & Short, John W., 2007, Two New Freshwater Prawns Of The Genus Macrobrachium Bate, 1868 (Crustacea: Decapoda: Palaemonidae) From The Kelian River, East Kalimantan, Indonesia, Raffles Bulletin of Zoology 55 (1), pp. 77-87 : 78-82

Macrobrachium urayang , new species

( Figs 1 , 2 )

Macrobrachium pilimanus – Holthuis, 1950: 214 (part).

Macrobrachium leptodactylus – Johnson, 1960: 265 (part), 1963: 13 (part); Chace & Bruce, 1993: 35 (part)(not Palaemon pilimanus de Man, 1879 ).

Material examined. – Holotype: male (13.0 mm CL) (MZB Cru 1459), Sg. Enggeng I’ut, a tributary of Sg. Bahau, Kayan basin, East Kalimantan, 18 Nov.1999.

Paratypes: Mahakam basin: 3 males (11.5–14.8 mm CL) , 1 female (8.9 mm CL) (QM W23118), Sg. Kelian, coll. R. & J. Powell, 27 May.1997 ; 1 male (13.5 mm CL) (MZB Cru 1476), Sg. Kelian, coll. R. & J. Powell, 27 May.1997 ; 3 juveniles (3.1–4.4 mm CL) , 2 males (5.9–11.3 mm CL), 2 ovigerous females (7.4–8.9 mm CL) ( ZRC 2000.2486 ), Sg. Kelian, coll. C. Yule, 5–7 Sep.1990 ; 1 female (6.5 mm CL) ( ZRC 2000.2487 ), Sg. Kelian, coll. C. Yule, Sep.1990 ; 1 male (7.3 mm CL) , 1 female (5.5 mm CL), 2 ovigerous females (6.6–7.3 mm CL) ( ZRC 2000.2488 ), Sg. Kelian, coll. C. Yule, Mar.1991 . Kayan basin : 23 males (6.2–13.7 mm CL) , 4 females (5.1–10.4 mm CL), 6 ovigerous females (8.3–10.7 mm CL) (MZB Cru 1460), same data as holotype ; 4 males (9.2–13.0 mm CL), 1 ovigerous female (9.6 mm CL) (QM W25715), same data as holotype ; 4 males (8.8-11.5 mm CL), 1 ovigerous female (9.8 mm CL) ( RMNH), same data as holotype ; 9 males (9.5–12.4 mm CL), 1 ovigerous female (9.2 mm CL) ( ZRC 2000.2479 ), same data as holotype ; 2 males (10.8–13.0 mm CL) , 3 females (9.8–12.7 mm CL) (MZB Cru 1461), Lalut Birai, tributary of Sg. Enggeng Bio draining into Sg. Bahau, 13-15 Nov.1999 ; 4 males (7.1–10.0 mm CL) ( RMNH), Sg. Seba Ai, tributary of Sg. Kayan, 22 Nov.1999 ; 1 juvenile (3.9 mm CL) , 12 males (5.4–12.0 mm CL) , 8 females (5.3–7.7 mm CL), 7 ovigerous females (8.1–8.6 mm CL) (MZB Cru 1462), Sg. Bako, tributary of Sg. Kayan, 23 Nov.1999 ; 2 males (10.4–10.6 mm CL), 2 ovigerous females (8.1 mm CL) (QM W25716), Sg. Bako, tributary of Sg. Kayan, 23 Nov.1999 ; 1 male (5.9 mm CL), 2 ovigerous females (9.1–10.1 mm CL) (MZB Cru 1463), Sg. Panan, tributary of Sg. Iwan draining to Sg. Kayan, 25 Nov.1999 ; 6 males (8.7–13.4 mm CL) , 4 females (6.9–8.0 mm CL), 18 ovigerous females (8.4–10.8 mm CL) (MZB Cru 1464), Sg. Nah, tributary of Sg. Kayan, 27 Nov.1999 ; 2 males (8.0– 10.6 mm CL) , 1 female (7.4 mm CL), 1 ovigerous female (12.7 mm CL) ( USNM), Sg. Nah, tributary of Sg. Kayan, 27 Nov.1999 ; 4 males (8.4-12.5 mm CL), 6 ovigerous females (8.0– 9.5 mm CL) ( ZRC 2000.2480 ), Sg. Nah, tributary of Sg. Kayan, 27 Nov.1999 .

Others: Mahakam basin: 8 juveniles, 12 males, 13 females, 7 ovigerous females (MZB Cru 1561), Sg. Lakan at Lakan Bilem village , coll. D. Wowor, 9–10 Jun.2006 ; 1 male (MZB Cru 1562), Sg. Mapan at Jantur Mapan , Bigung village, coll. D. Wowor, 10 Jun.2006 . Kayan basin: 24 males, 4 females, 16 ovigerous females (MZB Cru 1465), Sg. Bahau at Long Pujungan , coll. S. Wirjoatmodjo, Aug.1999 ; 3 males, 1 female (MZB Cru 1466), Sg. Enggeng Bio draining to Sg. Bahau, 14 Nov.1999; 1 male, 1 female (ZRC 2000.2481), Sg. Enggeng Bio draining to Sg. Bahau, 15 Nov.1999; 4 juveniles, 14 males, 7 females, 15 ovigerous females (MZB Cru 1467), Sg. Batu Baya, tributary of Sg. Bahau, 16 Nov.1999; 1 male, 1 female (MZB Cru 1468), Lalut Sem, tributary of Sg. Bahau, 16 Nov.1999; 1 juvenile, 3 males, 2 females, 6 ovigerous females (MZB Cru 1469), Lalut Putu Loten, tributary of Sg. Bahau, 17 Nov.1999; 2 juveniles, 52 males, 11 females), 2 ovigerous females (MZB Cru 1470), Sg. Enggeng I’ut, a tributary of Sg. Bahau, 18 Nov.1999; 34 males, 1 female, 2 ovigerous females (ZRC 2000.2482), Sg. Enggeng I’ut, a tributary of Sg. Bahau, 18 Nov.1999; 3 males, 5 ovigerous females (MZB Cru 1471), Sg. Bua Alat, a tributary of Sg. Bahau, 18 Nov.1999; 4 males, 3 females, 5 ovigerous females (MZB Cru 1472), Sg. Pingai, tributary of Sg. Kayan, 20 Nov.1999; 7 juveniles, 8 males, 1 female, 2 ovigerous females (ZRC 2000.2483), Sg. Mutai, tributary of Sg. Kayan, 20 Nov.1999; 11 juveniles, 16 males, 13 females, 28 ovigerous females (MZB Cru 1473), Sg. Seba Ai, tributary of Sg. Kayan, 22 Nov.1999; 7 juveniles, 21 males, 20 females, 18 ovigerous females (ZRC 2000.2484), Sg. Seba Ai, tributary of Sg. Kayan, 22 Nov.1999; 21 males, 7 females, 9 ovigerous females (MZB Cru 1474), Sg. Nah, tributary of Sg. Kayan, 27 Nov.1999; 1 juvenile, 21 males, 8 females, 8 ovigerous females (ZRC 2000.2485), Sg. Nah, tributary of Sg. Kayan, 27 Nov.1999; 104 juveniles, 33 males, 11 females (MZB Cru 1475), S. Kayan, 29 Nov.1999. Sebuku basin: 4 males, 8 ovigerous females (ZRC 1995.470), Sg. Bantul at Bantul logging camp, draining to Sg. Tulit, coll. M. Kottelat, 10 Feb.1993 ; 1 male, 1 female, 1 ovigerous female (ZRC 1995.476), Sg. Tulit at Kalonsayan , coll. M. Kottelat, 12 Feb.1993 ; 2 males, 2 ovigerous females (ZRC 1995.518), Stream at Km 18-19 on road from Semunad to Bantul logging camp, a tributary of Sg. Tikung, coll. M. Kottelat, 18 Feb.1993 .

Diagnosis. – A subcylindrical body form species. Rostrum short, reaching mid-line or slightly extending beyond end of second segment of antennular peduncle; moderately slender; dorsal carina slightly convex. Rostral formula: 4–5) 9-13/ 1- 2 teeth. Inferior orbital margin moderately produced, obtuse, postantennular carapace margin evenly rounded. Carapace spinose. Ocular beak moderately developed. Epistome bilobed. Second pereiopod robust, similar in shape, unequal in size. Long velvety setae present on both chelae. Fingers with less than 10 teeth. Carpus long conical, shorter than chela, about as long as palm and merus. All segments covered with spines. Inner margins of carpus and merus of major cheliped covered with short velvety setae. T4 unarmed, with moderate posterior submedian plate; T5 with transverse plate with median notch; T8 with contiguous posteromedially anterior lobes, without median process posteriorly. Preanal carina present. Telson stout, glabrous, with about 8–12 pairs of long plumose subventral setae. Uropods glabrous; exopod with mobile mesial spine longer than distolateral tooth. Developed eggs large, maximum size 1.7 by 1.2 mm, ovoid, few.

Description of holotype. – Rostrum. Very short, 0.32 CL (0.36–0.41 in paratypes), reaching mid-line of or slightly extending beyond end of second segment of antennular peduncle; slender, maximum depth distinctly less than maximum dorsoventral diameter of cornea; lateral carina well developed, continuing almost to tip; dorsal carina slightly sinuous, bent downwards in front of orbit with tip directed anteriorly, teeth subequally spaced, 11 teeth (9–13, mode 11 or 12), 4 teeth (4 or 5, mode 4) completely postorbital, postorbital teeth on anterior 0.36 of carapace (0.28–0.39), teeth strong, relatively long, upwardly directed, more closely distributed above orbit; ventral carina with 1 tooth (1 or 2, mode 2), first tooth located at about distal half ( Fig. 1A ).

General cephalon. Ocular cornea well developed, 0.16 CL (0.15–0.17). Inferior orbital margin moderately produced, obtuse, postantennular carapace margin evenly rounded ( Fig. 1B ). Antennal spine sharp, slender, continuing posteriorly as 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 on dorsal and branchiostegal regions. Ocular beak moderately developed, without laterally expanded tip. Epistome completely bilobed, lobes with blunt rounded margin ( Fig. 1C ). Scaphocerite stout, 0.46 CL (0.45– 0.47), length 2.50 times maximum breadth (2.33–2.73), 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, 0.71 as long as penultimate (0.80–0.93); exopod shorter than ischiomerus

First pereiopods. Slender, exceeding scaphocerite by chela and distal three-fourths of carpus; fingers about as long as palm; carpus 1.77 chela length (1.46–1.64), 1.12 merus length (1.10–1.16); merus and ischium covered with spinules; scattered short stiff setae present on all segments, otherwise glabrous ( Fig. 1I ).

Second pereiopods. Similar in shape, unequal in size, robust; carpus of minor cheliped extend beyond end of scaphocerite. Major cheliped. Spinules abundant on all segments except fingers and distal half or two-thirds of palm; fingers, distal part of palm, inner margins of carpus and merus covered by tufts of long velvety setae, especially on fingers and palm; chela 1.70 CL (1.37–1.80), length 4.92 times width (4.26– 5.55), outer and inner margins slightly convex and concave respectively, upper and lower margins rounded; palm subcylindrical, about as broad as maximum merus width, slightly compressed, width 1.34 times depth (1.31–1.36); fingers 0.68 times palm length (0.71–0.94), gaping; dactylus with 6–8 medium-sized teeth, first tooth at proximal 0.8, pollex with 4–6 medium-sized teeth of equal size and 3 smaller teeth towards articulation of fingers, first tooth at proximal 0.7, teeth subequally distributed and obscured by long velvety setae, both fingers with oblique carina distally; fingers uncinate at tip; carpus 0.80 palm length (0.80–0.98), conically long, length 2.78 times distal width (2.42–3.84), 0.48 times chela length (0.47–0.51), 0.97 times merus length (0.95–1.00); merus not inflated, 1.81 times ischium length (1.45–1.96); ischium tapereds ( Figs. 2A, B ). Minor cheliped. Generally resembling major cheliped; spinules abundant on all segments except fingers and distal three-fourths of palm covered thickly by tufts of long velvety setae, especially on fingers; cheliped 0.61 times major cheliped (0.55–0.65); fingers 1.36 times palm length (1.32–1.76), gaping; dactylus with 5–8 small teeth, pollex with 7 or 8 small teeth, teeth subequally distributed along proximal half of cutting edges, obscured by long velvety setae; carpus shorter than chela,

conically long, 1.15 times palm length (1.23–1.31) and 1.05 merus length (0.98-1.02); merus subcylindrical and stout, 1.25 times ischium length (1.13–1.40); ischium shorter than merus, tapered ( Figs. 2C, D ).

Third pereiopods. Entire dactylus and distal half of propodus extend beyond scaphocerite; spinules present on all segments except ischium, few scattered short stiff setae present on all segments, otherwise glabrous ( Fig. 1J ); dactylus stout, curved, fringed with dorsolateral setae, ventral carina well developed ( Fig. 1K ); propodus length 6.00 times longer than width (6.43–7.14); 8 ventral spines distributed along length of propodus, 2 distal most spines paired; carpus 0.46 times propodus length (0.49–0.58); merus 1.23 times propodus length (1.22–1.27), 1.97 times ischium length (2.04–2.14).

Fourth pereiopods. Entire dactylus extend beyond scaphocerite; spinules present on all segments except ischium, few scattered short stiff setae present on all segments, otherwise glabrous; 8 ventral spines distributed along length of propodus, 2 distal most spines paired; merus 2.04 times ischium length (2.00–2.29).

Fifth pereiopods. Tip of dactylus reaching distal end of scaphocerite; spinules present on all segments except ischium, few scattered short stiff setae present on all segments, otherwise glabrous; 12 ventral spines distributed along length of propodus; merus 1.04 as long as propodus (0.93–1.00), 2.28 longer than ischium (1.93–2.29).

Thoracic sternum. T4 without median process; with moderate posterior submedian plate ( Fig. 1D ); T8 with contiguous posteromedially anterolateral lobes, without median process ( Fig. 1E ). Abdomen. Smooth, glabrous. Male abdominal sternites. First 3 abdominal sternites with medium-sized triangular median process of similar form and size ( Fig. 1F ). Inter-uropodal sclerite. Well developed, elevated as longitudinal preanal carina, carina medium-sized, about same size as posterolateral teeth of sixth abdominal somite. Telson . Moderate and stout, 3.50 times median width (3.06–3.44), lateral margins straight, convergent with 2 pairs of dorsal spines present, posterior subventral margin straight with blunt median point, median projection overreached by inner pair of posterior spines ( Fig. 1H ). Uropods. With acute distolateral tooth, mobile mesial spine slightly or distinctly longer than distolateral tooth ( Fig. 1G ), exopod 2.33 times longer than broad (2.11–2.21).

Etymology. – The specific name urayang is derived from Kayan dialect for prawn, language used by the indigenous Dayak Kayan of the interior East Kalimantan. The name is used as a noun in apposition.

Size. – Males reach larger sizes than females; the largest male recorded being 14.8 mm CL; the largest female 12.7 mm CL and ovigerous females are between 6.6 to 12.7 mm CL (n=49).

Remarks. – This new species has unequal robust second pereiopods, with both chelae being covered with long velvety setae; and the females have large and few eggs. These characters apparently compelled Holthuis (1950) to put specimens of this species under Macrobrachium pilimanus (de Man, 1879) . However, Johnson (1960, 1963) believed that the new species closely resembles Macrobrachium leptodactylus (de Man, 1892) . The two species share several characters such as a spinulate carapace; a T4 with a moderately sized posterior submedian plate; a T8 which has contiguous posteromedially anterior lobes but without a median process; the first three abdominal sternites having a moderately sized median process; and the second pereiopod having a long conical carpus and non-inflated merus. Nevertheless, Johnson (1963: 14) doubted the identity of this Bornean species stating that: “… the Bornean specimens may not belong to this species”. Macrobrachium urayang can be differentiated from M. leptodactylus in having longer and prominent rostral teeth (vs. short and not outstanding); a completely bilobed epistome (vs. partly bilobed); absence of preanal carina (vs. presence); fewer teeth on both chelae of second pereiopods (5–8 teeth vs. 11–16 teeth), shorter movable finger of the major second pereiopod chela (ratio of movable finger length to palm length 0.68–0.94 vs. 1.07– 1.63), fingers widely gaping (vs. moderately gaping), a relatively longer carpus (ratio of carpus length to merus length 0.95–1.00 vs. 0.78–0.90), the inner margin of carpus and merus having long velvety setae (vs. without long velvety setae), the entire second chelipeds having more and larger spinules (vs. less and smaller); the third to fifth pereiopods being spinulate (vs. glabrous); and the mobile mesial spine of the uropod being longer than the distolateral tooth (vs. shorter).

Although the specimens from the upper Kayan River which were collected by Dr. A. W. Nieuwenhuis in 1900, deposited in RMNH, Leiden, The Netherlands, are not examined in this study, the first author had collected a good series of this species from the upper Kayan River, which fit very well with Johnson’s drawing and short description of this Bornean species. Therefore, there is no doubt that the species collected by Dr. A. W. Nieuwenhuis is the same species as those collected.

Macrobrachium urayang also morphologically resembles M. malayanum ( Roux, 1934) . Both species have a spinulate carapace; a completely bilobed epistome; first three abdominal sternites each with a moderately sized median process; no preanal carina; a mobile mesial spine of the uropod which is longer than the distolateral tooth; major second pereiopod with fingers shorter than the palm, fingers widely gaping with 5–8 teeth, and the carpus about as long as the merus. However, Macrobrachium urayang can be distinguished from M. malayanum by several characters, i.e. shorter rostrum (ratio of rostrum length to carapace length 0.32–0.41 vs. 0.59–0.73), tip reaching to or slightly extending beyond the second segment of the antennular peduncle (vs. extending the end of the third segment of the antennular peduncle or slightly extending beyond the distal end of the scaphocerite), less ventral teeth (1–2 vs. 3–5); a T8 with contiguous posteromedially anterior lobes (vs. moderately separated); a major second pereiopod chela covered with long velvety setae (vs. short velvety setae), the inner margins of carpus and merus having long velvety setae (vs. without velvety setae), the minor second pereiopod chela being densely covered with long velvety setae (vs. scattered long stiff setae), both second chelipeds being covered with spinules (vs. spines); and the third to fifth pereiopods being robust (vs. slender) and spinulate (vs. glabrous).

Distribution. – Presently only known from the upper to the middle part of the Mahakam, Kayan and Sebuku River basins which drain to the Makassar Straits at the eastern coast of Kalimantan, Indonesian Borneo.

Comparative material examined. – Macrobrachium pilimanus : lectotype, male 14.95 mm CL (RMNH D 1477) Moearalaboeh [Muaralabuh], W. Sumatra, Indonesia, coll. Midden Sumatra Expedition , 1877 ; paralectotypes, 4 males (RMNH D 1477), same data as lectotype; 1 male (RMNH D 1095), Alahanpandjang [Alahanpanjang], W. Sumatra, Indonesia, coll. Midden Sumatra Expedition, 1877; ca. 50 specimens (RMNH D 2490), river near Alahanpandjang [Alahanpanjang], W. Sumatra, Indonesia, coll. Midden Sumatra Expedition, 1877; 2 males (MNHN Na. 13595 - ex. Museè de Leyde, 1899), river at Alahanpandjang [Alahanpanjang], W. Sumatra, Indonesia, coll. Midden Sumatra Expedition , 1877. M. leptodactylus : lectotype, male 16.0 mm CL (RMNH D 1801), Buitenzorg [Bogor], W. Java, coll. M. Weber, Mar.–Sep.1888 ; paralectotypes, male (RMNH D 38072), Buitenzorg [Bogor], W. Java, coll. M. Weber, Mar.–Sep.1888 ; 5 males (ZMA De 102564), Buitenzorg [Bogor], W. Java, coll. M. Weber, Mar.– Sep.1888 .

Figures

Fig. 1. Macrobrachium urayang, new species, holotype, male 13.00 mm CL, MZB Cru 1459: A, lateral view of carapace; B, postantennular carapace margin; C, epistome; D, T4; E, T8; F, first 3 abdominal sternites; G, mobile mesial spine of exopod of uropod; H, telson; I, first pereiopod; J, third pereiopod; K, dactylus of third pereiopod. Scale bars: A = 5 mm; I–J = 2 mm; B–H, K = 1 mm.

Fig. 2. Macrobrachium urayang, new species, holotype, male 13.00 mm CL, MZB Cru 1459: A, lateral view of major second pereiopod; B, same, cheliped, denuded, dorsal view; C, lateral view of minor second pereiopod; D, same, cheliped, denuded, dorsal view. Scale bars: A, C = 5 mm; B, D = 2 mm.