Caridina profundicola, Rintelen & Cai, 2009

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 : 396-401

Caridina profundicola , new species

( Figs.30–32 ; Table 12)

Material examined. – Holotype: male (cl 3.5 mm)( MZB Cru 1549), Lake Towuti , Loeha Island, southwest shore, 02°45.58'S, 121°31.14'E, loc. 149-04, on boulders in deeper water, coll. K. & T. von Rintelen, 5 Aug.2004.

Paratypes ( Lake Towuti ) – 7 ex. ( MZB Cru 1552, n=3; ZMB 29025, n=4, some SEM material), east shore, south of Cape Tomeraka, 02°44.47'S, 121°37.53'E, loc. 70-03, on boulders in deeper water, coll. K . & T. von Rintelen , 9 Oct.2003 ; 6 ex. ( ZMB 29054a, n=3; some SEM material; ZMB 29054b, n=3), west shore, at entrance to outlet bay, Cape Larona, 02°48.43'S, 121°24.75'E, loc. 73-03, (a) on boulders in deeper water, (b) on leaf litter, coll. K . & T. von Rintelen , 8 Oct.2003 ; 6 ex. ( MZB Cru. 1553, n=3; ZMB 29055, n=3, some SEM material), Loeha Island, north shore, 02°45.64'S, 121°34.32'E, loc. 97-03, on boulders in deeper water, coll. K . & T. von Rintelen , 4 Oct.2003 ; 1 ex. ( ZMB 29305), west shore, Cape Larona, 02°48.526'S, 121°25.044'E, loc. 120-04, on boulders in deeper water, coll. K . & T. von Rintelen , 29 Jul.2004 ; 5 ex. ( ZMB 29435, some SEM material), Loeha Island , north shore, 02°45.324'S, 121°32.019'E, loc. 226-05, on boulders in deeper water, coll. K . & T. von Rintelen , 23 Oct.2005 ; 9 ex. ( MZB Cru. 1550), Loeha Island, southwest shore, 02°45.58'S, 121°31.14'E, loc. 149-04, on boulders in deeper water, coll. K . & T. von Rintelen , 5 Aug.2004 ; 2 ex. ( MZB Cru. 1551), northeast shore, at Cape Noote, 02°39.751'S, 121°39.195'E, loc. 117-04, on boulders in deeper water, coll. K . & T. von Rintelen , 28 Jul.2004 .

Description. – Carapace length 2.7-4.9 mm (n=35). Rostrum ( Fig. 31 A-C; Table 12) very long and slender, proximal part triangular widened, equally pronounced in male and female, reaching far beyond scaphocerite; 1.4-2.8 times as long as carapace (n=34), armed dorsally with 16-25 teeth, including 2-3 posterior to orbital margin, dorsal teeth throughout less densely spaced than ventral teeth, armed ventrally with 13-24 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 0.8-1.1 times as long as carapace (n=5), second segment 1.8-2.0 times length of third segment, third segment 0.2-0.3 times length of basal segment. Stylocerite reaching 0.9-1.0 times length of antennular peduncle (n=5). Scaphocerite ( Fig. 31E ) 3.4-5.1 times as long as wide (n=22).

Sixth abdominal somite 0.7-1.0 times length of carapace (n=35), 1.5-2.1 times as long as fifth somite (n=22), 0.9-1.1 times length of telson (n=30). Telson ( Fig. 31F,K ) 3.4-4.0 times as long as wide (n=5), distal margin rounded, without projection, with 2-4 pairs of spinules and 1 pair of dorsolateral spinules (n=22); distal end with 4 pairs of spines, lateral pair distinctly longer than intermediate pairs, median pair shortest. Preanal carina ( Fig. 31G ) with a spine. Uropodal diaeresis ( Fig. 31D ) with 9-11 movable spinules (n=9).

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 absent from all pereiopods. Incisor process of mandible ( Fig. 32A ) ending in a row of 2-3 small teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 32B ) broadly rounded, upper lacinia elongate, with numerous distinct teeth and setae on inner margin, palp slender. Upper endites of maxilla ( Fig. 32C ) subdivided, palp very slender, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Distal end of palp of first maxilliped ( Fig. 32D ) triangular, with a long finger-like projection; flagellum of the exopod very elongated, endopod high, reaching half the flagellum of exopod in length. Second maxilliped ( Fig. 32F ) typical. Third maxilliped ( Fig. 32E ) with ultimate segment distinctly shorter than penultimate segment.

First and second pereiopod very slender, chela and carpus of first pereiopod distinctly stouter and broader than chela and carpus of second pereiopod ( Fig. 31 M-O); chela of first pereiopod 2.9-4.4 times as long as wide (n=20), 0.8-1.1 times length of carpus (n=34); tips of fingers rounded, without hooks; dactylus 1.0-1.3 times as long as palm (n=6); carpus 4.2-5.6 times as long as wide (n=20), 1.3-1.5 times length of merus (n=5). Chela of second pereiopod 4.3-6.1 times as long as wide (n=20), 0.6-0.7 times length of carpus (n=34); tips of fingers rounded, without hooks, dactylus 1.1-1.2 times as long as palm (n=6); carpus 8.8-12.2 times as long as wide (n=20), 1.3-1.6 times as long as merus (n=5).

Third pereiopod ( Fig. 31I,L ) slender, dactylus 5.8-7.8 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 1-2 accessory spines on flexor margin (n=16); propodus 14.0- 19.0 times as long as wide (n=5), 3.2-4.1 times as long as dactylus; carpus 6.9-8.2 times as long as wide, 0.6 times as long as propodus, 0.4-0,5 times as long as merus; merus 11.5-15.7 times as long as wide, bearing 3-4 strong, movable spines on posterior margin of outer surface.

Fifth pereiopod slender ( Fig. 31H,J ), dactylus 6.2-8.3 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 34-44 (n=7) accessory spines on flexor margin; propodus 20.4-22.8 times as long as wide (n=5), 3.6-4.6 times as long as dactylus; carpus 6.6-9.3 times as long as wide, 0.5 times as long as propodus, 0.5-0.6 times as long as merus; merus 10.7-14.3 times as long as wide, bearing 3 strong, movable spines on posterior margin of outer surface (n=2).

Endopod of male first pleopod ( Fig. 31P ) elongated triangular, 1.8-2,2 times as long as proximally wide (n=5), without appendix interna. Appendix interna of male second pleopod ( Fig. 31Q ) 0.8-1.0 times length of appendix masculina (n=5).

Ovigerous females with 41- 80 eggs (n= 9 females); egg size 0.7-0.9 x 0.4-0.6 mm (n=202, eggs with and without eyes).

Distribution. – Endemic to Lake Towuti ( Fig. 30A ).

Biology and ecology. – C. profundicola is a hard substrate dweller. Adult specimens of this species were exclusively found in deeper water regions, approx. below 3 m, although two juveniles were collected among leaf litter in shallow water. The majority of species was found between large rocks (boulders), often together with C. spinata . C. profundicola is a rather inactive species, which keeps still when disturbed (KvR pers. observation), although it is capable of very fast movements if necessary.

Colour pattern. – Body and appendages yellowishtransparent, sometimes slightly red, usually with two conspicuous yellow transversal stripes on the abdomen ( Fig. 30B ). Eggs green, contrasting the body colour. The yellow stripes are also already distinctive in juveniles.

Etymology. – Caridina profundicola refers to the unusually deep occurrence of this new species in the Malili lake system.

The name is a combination of the Latin words profundus (depths) and collere (to inhabit).

Taxonomic remarks. – C. profundicola differs from all Malili species by the characteristic triangular shape of the proximal part of the otherwise very slender rostrum. A similar triangular shape is only pronounced in C. lingkonae , but differs by a distinctly more slender and also longer rostrum compared to carapace length (1.4-2.8, median 1.9 vs. 1.0-1.6, median 1.2 in C. lingkonae ), and a higher number of ventral teeth (13-24, median 20 vs. 7-18, median 12 in C. lingkonae ).

C. profundicola (2.7-4.9 mm, median 4.0 mm) and C. spinata (carapace length 3.0-5.0 mm, median 4.2 mm) are the largest lacustrine species in the Malili system. Both show similar slender pereiopods and often occur on the same substrate (usually boulders in deeper water) at the same locality, but differ in the shape of the rostrum (proximal part triangular while distal part distinctly slender vs. not triangular, but rather uniformly slender in C. spinata ), a longer rostrum compared to the carapace length (1.4-2.8, median 1.9 vs. 0.9-1.7, median 1.2 in C. spinata ), a larger number of ventral teeth on the rostrum (13-24, median 20 vs. 5-12, median 9 in C. spinata ) and on the dactylus of the fifth pereiopod (34-44, median 39 vs. 25-31, median 29 in C. spinata ), respectively, and a lower number of spines on the uropodal diaeresis (9- 11, median 10 vs. 12-16, median 14 in C. spinata ). Both species differ in their behaviour: C. profundicola is distinctly more inactive and can almost be caught by hand, while C. spinata always appears rather active. With its extremely long and slender rostrum, C. profundicola further resembles C. ensifera and C. caerulea from Lake Poso, but differs in the triangular shape and the constant denticulation (vs. always with an unarmed gap in both Poso species).

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

Figures

Fig. 30. Caridina profundicola from the Malili lake system. A. Distribution. B. Colour pattern of living animal (not to scale). Picture courtesy of Rainer Masche.

Fig. 31. Caridina profundicola from the Malili lake system. A. Cephalothorax and cephalic appendages, female (ZMB 29025); B. Rostrum, other female (ZMB 29025); C. Rostrum, female (ZMB 29054a); D. Uropodal diaeresis, female (ZMB 29025); E. Scaphocerite, male (ZMB 29025), F. Telson, female (ZMB 29025); G. Preanal carina; H. Fifth pereiopod; I. Third pereiopod; J. Dactylus of fifth pereiopod; K. Distal end of telson; L. Dactylus of third pereiopod; M. First pereiopod, female (ZMB 29054a); N. Second pereiopod; O. SEM image of chela and carpus of first and second pereiopods, female (ZMB 29025); P. Endopod of male first pleopod (ZMB 29025); Q. Appendix masculina of male second pleopod. Scale bars: A-C, E = 1.0 mm; F-I, M-Q = 0.5 mm; D, J-L = 0.1 mm.

Fig. 32. Caridina profundicola from the Malili lake system. A. Mandible (MZB Cru 1552); B. Maxillula; C. Maxilla; D. first maxilliped; E. third maxilliped; F. second maxilliped. Scale bars: A-F = 1mm.

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).