Caridina tenuirostris Woltereck, 1937a

Rintelen, Kristina von & Cai, Yixiong, 2009, Radiation Of Endemic Species Flocks In Ancient Lakes: Systematic Revision Of The Freshwater Shrimp Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Atyidae) From The Ancient Lakes Of Sulawesi, Indonesia, With The Description Of Eight New Species, Raffles Bulletin of Zoology 57 (2), pp. 343-452 : 415-420

Caridina tenuirostris Woltereck, 1937a

( Figs. 42–45 ; Table 16)

Caridina tenuirostris Woltereck, 1937a: 224 , fig. I.8, pls. 3,6 (type locality: Lake Towuti at Lingkona).

Caridina tenuirostris – Woltereck, 1937b: 309, fig. 12; Chace 1997: 20; von Rintelen et al., 2008: 2244, Table 1.

Cardina tenuirostris – Brooks, 1950: 168 (erroneous spelling).

Caridina Towutensis – Woltereck, 1937a: 220, fig. I.2, pls. 3,6 (type locality: Lake Towuti, South).

Caridina towutensis – Woltereck, 1937b: 301, fig. 7 (type locality further specified as Lake Towuti, South, Cape Sirioga); Chace, 1997: 20; von Rintelen et al., 2008: 2244, Table 1.

Cardina towutensis – Brooks, 1950: 168 (erroneous spelling).

Material examined. – Neotype: ovigerous female (cl. 2.8 mm), Lake Towuti , southwest shore, west of Cape Tetetu, 02°54.13'S,

cl (mm) 2.4-3.3 2.9 ± 0.2 2.9 32 rl / cl 1.1-1.8 1.5 ± 0.2 1.4 32 n dorsal rostral teeth 9-18 14 ± 2 14 32 n ventral rostral teeth 10-24 14 ± 3 15 32 abds6 / cl 0.6-0.9 0.8 ± 0.0 0.8 32 abds6 / abds5 1.8-2.3 2.0 ± 0.1 1.9 20 abds6 / h tel 1.0-1.5 1.2 ± 0.1 1.3 12 h tel / w tel 2.8-5.7 3.6 ± 1.2 3.4 5 n spines uropodal diaeresis 7-8 8 ± 0 8 5 h ch1 / w ch1 1.7-2.3 1.9 ± 0.2 1.9 20 h ch1 / h ca1 1.3-1.7 1.5 ± 0.1 1.5 32 h ca1 / w ca1 1.5-2.4 1.8 ± 0.2 1.8 20 h ch2 / w ch2 1.9-3.1 2.4 ± 0.4 2.3 20 h ch2 / h ca2 0.8-1.0 0.9 ± 0.1 0.9 32 h ca2 / w ca2 3.1-5.0 4.0 ± 0.7 3.8 20 n spines p3 3 - - 6 n spines p5 11-15 13 ± 1.7 14 6

121°23.78'E, loc. 76-03, on wood ( MZB Cru 2126), coll. K. & T. von Rintelen, 28 Sep.2003 .

Others (Lake Towuti) – 32 ex. ( MZB Cru 1782, n=17; ZMB 29034, n=15, some SEM material), east shore, south of Cape Tomeraka, 02°44.47'S, 121°37.53'E, loc. 70-03, on wood, coll. K . & T. von Rintelen , 27 Sep.2003 ; 27 ex. ( MZB Cru 1783, n=15; ZMB 29043, n=12), wet shore, at entrance to outlet bay, Cape Larona, 02°48.43'S, 121°24.75'E, loc. 73-03, on wood, coll. K . & T. von Rintelen , 27 Sep.2003 ; 30 ex. ( MZB Cru 1784, n=15; ZMB 29122, n=15), north shore, bay east of Cape Bintu, 02°39.48'S, 121°33.25'E, loc. 68-03, on wood, coll. K . & T. von Rintelen , 26 Sep.2003 ; 10 ex. ( ZMB 29123), east shore, 02°52.79'S, 121°31.18'E, loc. 72-03, on wood, coll. K . & T. von Rintelen , 27 Sep.2003 ; 12 ex. ( ZMB 29124), Loeha Island , west shore, 02°45.5'S, 121°31.06'E, loc. 95-03, on wood, coll. K . & T. von Rintelen , 4 Oct.2003 ; 35 ex. ( MZB Cru 1785, n=12; ZMB 29127, n=23, some SEM material), north shore, at cape, 02°29.73'S, 121°29.73'E, loc. 67-03, on wood, coll. K . & T. von Rintelen , 26 Sep.2003 ; 6 ex. ( ZMB 29132), southwest shore, Cape Sioloya , 02°50.7'S, 121°26.32'E, loc. 77-03, on wood, coll. K . & T. von Rintelen , 28 Sep.2003 ; 34 ex. ( MZB Cru 1786, n=20; ZMB 29133, n=14), southwest shore, west of Cape Tetetu, 02°54.13'S, 121°23.78'E, loc. 76-03, on wood, coll. K . & T. von Rintelen , 28 Sep.2003 ; 6 ex. ( ZMB 29134), west shore, north of Cape Wasupute , 02°46.9'S, 121°27.94'E, loc. 78-03, on wood, coll. K . & T. von Rintelen , 28 Sep.2003 ; 26 ex. ( MZB Cru 1787, n=9; ZMB 29300, n=17), east shore, 02°43.82'S, 121°39.211'E, loc. 115-04, on wood, coll. K . & T. von Rintelen , 28 Jul.2004 ; 3 ex. ( ZMB 29311), west shore, west of Cape Timbalo , 02°42.631'S, 121°26.389'E, loc. 145-04, on mixed substrate with wood, coll. K . & T. von Rintelen , 26 Jul.2004 ; 7 ex. ( MZB Cru 1788, n=4; ZMB 29312, n=3), west shore, Cape Bakara, 02°40.771'S, 121°26.11'E, loc. 144-04, on mixed substrate with wood, coll. K . & T. von Rintelen , 26 Jul.2004 ; 3 ex. ( ZMB 29450), west shore, Cape Bakara , 02°40.876'S, 121°26.043'E, loc. 225-05, on wood, coll. K . & T. von Rintelen , 23 Oct.2005 ; 13 ex. ( ZMB 29130, n=13 and some juveniles, some SEM material), Larona River , close to outlet bay, 02°45.8'S, 121°20.8'E, loc. 51-03, on wood, coll. K . & T. von Rintelen , 21 Sep.2003 .

Others (Lake Mahalona) – 47 ex. ( MZB Cru 1789, n=23 and some juveniles; ZMB 29040, n=24, some SEM material), northwest shore, at cape, 02°34.72'S, 121°29.12'E, loc. 56-03, on wood, coll. K . & T. von Rintelen , 23 Sep.2003 ; 3 ex. ( ZMB 29224), east shore, 02°34.217'S, 121°30.681'E, loc. 147-04, on wood, coll. K . & T. von Rintelen , 3 Aug.2004 ; 6 ex. ( ZMB 29071), Tominanga River , approx. 2.2 km north of Lake Towuti, 02°36.5'S, 121°31.78'E, loc. 58-03, on wood, coll. K . & T. von Rintelen , 23 Sep.2003 .

Description. – Carapace length 2.4-3.3 mm (n=32). Rostrum ( Fig. 43 A-B; Table 16) long and throughout slender, reaching far beyond end of scaphocerite, 1.1-1.8 times as long as carapace (n=32), armed dorsally with 9-18 teeth (including 1-4 teeth posterior to orbital margin), approx. anterior 2/3 to ½ unarmed, without subapical teeth, armed ventrally with 10-24 teeth. Antennal spine situated below inferior orbital angle. Pterygostomial angle broadly rounded. Eyes well developed, anterior end 0.6-0.7 times length of basal segment of antennular peduncle (n=5). Antennular peduncle 0.9-1.0 times as long as carapace (n=5), second segment 1.9-2.2 times length of third segment, third segment 0.3 times length of basal segment. Stylocerite reaching 0.8-0.9 times length of basal segment of antennular peduncle (n=5). Scaphocerite ( Fig. 43F ) 4.3-5.4 times as long as wide (n=5).

Sixth abdominal somite 0.6-0.9 times length of carapace (n=32), 1.8-2.3 times as long as fifth somite (n=20), 1.0-1.5 times length of telson (n=12). Telson ( Fig. 43E,K ) 2.8-5.7 times as long as wide (n=5), distal margin rounded, without projection, with 3-4 pairs of spinules and 1 pair of dorsolateral spinules; distal end with 3-5 pairs of spines, lateral pair distinctly longer than intermediate pairs, median pair shortest. Preanal carina ( Fig. 43C ) with a spine. Uropodal diaeresis ( Fig. 43D ) with 7-8 movable spinules (n=5).

5 pairs of pleurobranchs well developed; 3 pairs of arthrobranchs, 2 on third maxillipeds, with second pair strongly reduced in size, 1 pair on first pereiopod; 1 pair of podobranchs on second maxilliped reduced strongly to a laminate form. Epipod on first pereiopod. Incisor process of mandible ( Fig. 44A ) ending in a row of 3-4 small teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 44B ) broadly rounded, upper lacinia elongate, with numerous distinct teeth and setae on inner margin, palp slender. Upper endites of maxilla ( Fig. 44C ) subdivided, palp elongated, scaphognathite broadly tapering posteriorly with numerous long, curved setae at posterior end. Distal end of palp of first maxilliped ( Fig. 44F ) triangular, ending with a finger-like projection; flagellum of the exopod short, endopod high, not exceed the flagellum of exopod in length. Second maxilliped ( Fig. 44E ) typical. Third maxilliped ( Fig. 44D ) ultimate segment slightly shorter than penultimate segment.

Chela and carpus of first pereiopod distinctly stouter and broader than chela and carpus of second pereiopod ( Fig. 43 L-N); chela of first pereiopod 1.7-2.3 times as long as wide (n=20), 1.3-1.7 times length of carpus (n=32); tips of fingers rounded, without hooks; dactylus 1.0-1.6 times as long as palm (n=5); carpus 1.5-2.4 times as long as wide (n=20), 1.0-1.6 times length of merus (n=5). Chela of second pereiopod 1.9-3.1 times as long as wide (n=20), 0.8-1.0 times length of carpus (n=32); tips of fingers rounded, without hooks, dactylus 1.5-1.7 times as long as palm (n=5); carpus 3.1-5.0 times as long as wide (n=20), 1.1-1.3 times as long as merus (n=5).

Third pereiopod ( Fig. 43G,I ) slender, dactylus 2.0-3.2 times as long as wide (terminal spine included, without spines of flexor margin; n=6), terminating in one large claw with 3 accessory spines on flexor margin; propodus 8.6-12.2 times as long as wide, 4.3-6.8 times as long as dactylus; carpus 3.6-5.2 times as long as wide, 0.5-0.6 times as long as propodus, 0.5 times as long as merus; merus 6.8-8.3 times as long as wide, bearing 2-3 strong, movable spines on posterior margin of outer surface.

Fifth pereiopod slender ( Fig. 43H,J ), dactylus 2.5-3.3 times as long as wide (terminal spine included, without spines of flexor margin; n=6), terminating in one large claw with 11- 15 accessory spines on flexor margin; propodus 10.5-14.4 times as long as wide, 4.8-6.4 times as long as dactylus; carpus 3.9-4.6 times as long as wide, 0.5-0.6 times as long as propodus, 0.6 times as long as merus; merus 6.1-7.3 times as long as wide, bearing 2 strong, movable spines on posterior margin of outer surface.

Endopod of male first pleopod ( Fig. 43O ) elongated triangular, 1.6-2.3 times as long as proximally wide (n=5), without appendix interna. Appendix interna of male second pleopod ( Fig. 26P ) 0.9-1.0 times as long as appendix masculina (n=5).

Ovigerous females with 11- 22 eggs (n= 3 females); egg size 0.8-0.9 x 0.5-0.6 mm (n=51, eggs with and without eyes).

Distribution. – C. tenuirostris is endemic to the Malili lake system. It occurs in Lake Towuti, Lake Mahalona, and the connecting Tominanga River as well as Larona River close to the outlet bay of Lake Towuti ( Fig. 42A ; for localitiy names see Fig. 1.C ).

Biology and ecology. – With its rather stout first and second pereiopods, C. tenuirostris represents a typical hardsubstrate dweller. The majority of specimens were collected from wood. It often occurs syntopically on wood with C. lanceolata in Lake Towuti and Lake Mahalona, but whereas C. lanceolata occurs on various substrates, the occurrence of C. tenuirostis is mainly restricted to wood.

Colour pattern. – The primary colour of C. tenuirostris is brown with several white transversal stripes all over the body ( Fig. 42B ). A conspicuous white band is visible at the distal part of the abdomen. Appendages are transparent or partly brownish. This colour pattern remains visible even if the shrimp is under stress, though the intensity of the colour merely fades.

Taxonomic remarks. – The arrangement of rostral teeth slightly resembles that in C. lanceolata , but C. tenuirostris has a distinctly more slender rostrum, a higher number of ventral teeth (10-24, median 15 vs. 4-13, median 7 in C. lanceolata ), always lacking subapical teeth, and a shorter sixth abdominal somite compared to carapace length (0.6-0.9, median 0.8 vs. 0.8-1.1, median 1.0 in C. lanceolata ). The pereiopods are further distinctively stouter than in C. lanceolata . The colour pattern of C. tenuirostris closely resembles C. glaubrechti , but both species not only differ in their substrate preference (wood vs. rocks in C. glaubrechti ), but by the continuous dorsal denticulation of the rostrum (vs. anterior dorsal part always completely unarmed in C. tenuirostris ), a different number of spines on the uropodal diaeresis (7-8, median 8 vs. 11-14, median 12 in C. glaubrechti ), and on the dactylus of the fifth pereiopod (11-15, median 14 vs. 14-35, median 28 in C. glaubrechti ).

In the molecular phylogeny ( Figs. 63-64 ), C. tenuirostris is genetically distinct from all other ancient lake species.

Woltereck’s (1937a) species C. towutensis was never reported by any later collectors, e.g. neither by M. Kottelat nor C. Schubart (see Cai et al., 2009), and was not found during fieldwork for this study at the Malili lakes including an exhaustive search at the (presumed) type locality at Cape Sirioga [Sioloya], Lake Towuti, in 2005 ( Fig. 45A ; Yixiong Cai, K. & T. von Rintelen, pers. field observation). However, at this locality (loc. 77-03) other species were found, i.e. C. lanceolata , C. parvula , C. masapi , and C. tenuirostris . A possible explanation could be the extinction of this tiny species (“total length of largest specimen including the rostrum 16 mm ”; Woltereck, 1937b: 301), but this seems unlikely for no other species has become extinct since Woltereck’s descriptions. A rather more plausible explanation is the misinterpretation of C. towutensis as a distinct species. Woltereck examined only nine specimens and might have incidentally described local variations of another species. Woltereck’s drawing of the rostrum ( Fig. 45B ) closely resembles juveniles or small adults (usually males) of C. tenuirostris , that have not developed full rostrum length yet. Consequently, we here synonymize C. towutensis with C. tenuirostris .

Figures

Fig. 42. Caridina tenuirostris from the Malili lake system. A. Distribution. B. Colour pattern of living animal (not to scale). Picture courtesy of Rainer Masche.

Fig. 43. Caridina tenuirostris from the Malili lake system. A. Cephalothorax and cephalic appendages, male (ZMB 29127); B. Woltereck’s drawing of the rostrum (modified from 1937a); C. Preanal carina, male (ZMB 29127); D. Uropodal diaeresis; E. telson, female (ZMB 29127); F. Scaphocerite, male (ZMB 29127); G. Third pereiopod; H. Fifth pereiopod; I. Dactylus of third pereiopod; J. Dactylus of fifth pereiopod; K. Distal end of telson, female (ZMB 29127); L. First pereiopod, male (ZMB 29127); M. Second pereiopod; N. SEM image of chela and carpus of first and second pereiopods, female (ZMB 29071); O. Endopod of male first pleopod (ZMB 29127); P Appendix masculina of male second pleopod. Scale bars: A, F = 1.0 mm; C, E, G-H, L-P = 0.5 mm; D, I-K = 0.1 mm; B = no scale available.

Fig. 44. Caridina tenuirostris from the Malili lake system. A. Mandible (ZMB 29133); B. Maxillula; C. Maxilla; D. third maxilliped; E. second maxilliped; F. first maxilliped. Scale bars: A-F = 1mm.

Fig. 45. Caridina towutensis sensu Woltereck (1937a, b). A. The presumed type locality in Lake Towuti. B. Woltereck’s drawing of the rostrum (modified from 1937a).

Fig. 26. Caridina masapi from the Malili lake system. A. Mandible (ZMB 29277); B. Maxillula; C. Maxilla; D. third maxilliped; E. second maxilliped; F. first maxilliped. Scale bars: A-F = 1mm.

Fig. 1. The ancient lakes of Sulawesi. A. The two ancient lake systems on the Indonesian island Sulawesi. B. Overview of Caridina collecting sites from Lake Poso. C. Overview of Caridina collecting sites from the Malili lake system.

Fig. 63. Bayesian Inference phylogram (mtDNA, 16S and COI) of Caridina from the ancient lakes of Sulawesi (for other taxa compare von Rintelen et al., in review). Numbers on branches are, from top, Bayesian posterior probabilities, ML and MP bootstrap values. The scale bar indicates the number of substitutions per site. For each sequenced specimen museum accession numbers are provided. Locality abbreviations (compare Fig. 1): Lam (Lampesue River catchment), LT (Lake Lontoa), MHL (Lake Mahalona), MS (Lake Masapi), MT (Lake Matano), MTca (Lake Matano catchment), Pat (Patingko River), Pon (Ponsoa River), TW (Lake Towuti), TWca (Lake Towuti catchment), PS (Lake Poso), PSca (Lake Poso catchment), SSul (South Sulawesi), SESul (Southeast Sulawesi).

Fig. 64. Bayesian Inference phylogram (mtDNA, 16S and COI) showing taxa within the two Malili clades (for other taxa compare von Rintelen et al., 2009). For each sequenced specimen museum accession numbers are provided. Locality abbreviations (compare Fig. 1): Lam (Lampesue River catchment), LT (Lake Lontoa), MHL (Lake Mahalona), MS (Lake Masapi), MT (Lake Matano), MTca (Lake Matano catchment), Pat (Patingko River), Pon (Ponsoa River), TW (Lake Towuti), TWca (Lake Towuti catchment), SSul (South Sulawesi).