Caridina caerulea, 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 : 428-432

Caridina caerulea , new species

( Figs. 51–53 ; Tables 19 –20)

Caridina ensifera Schenkel, 1902 pro parte: 490, pl. 8, Figs. 1 a-e, 4d (type locality: Lake Poso).

Caridina ensifera – Cai & Wowor, 2007 pro parte: 311, Figs. 1-2 .

Caridina ensifera “blue” – von Rintelen et al., 2007a: 1034, Figs. 1-2 , Tables 1-2.

Material examined. – Holotype –male (cl 4.4 mm)( MZB Cru 2123), Lake Poso , west shore, Cape Bancea, 01°59.023'S, 120°35.108'E, loc. 59-04, on rocks in shallow water, coll. M. Glaubrecht & T. von Rintelen, 29 Mar.2004.

Paratypes ( Lake Poso ) – 1 ex. ( ZMB 29207), east shore, 01°59.867'S, 120°41.238'E, loc. 160-04, on mixed substrate, coll. K . & T. von Rintelen , 16 Aug.2004 ; 17 ex. ( MZB Cru 1718, n=9; ZMB 29251, n=8, some SEM material), south shore, Pendolo, beach at Hotel Mulia, 02°3.876'S, 120°41.587'E, loc. 50-04, on wood, coll. M. Glaubrecht & T. von Rintelen , 27 Mar.2004 ; 16 ex. ( MZB Cru 1719, n=7; ZMB 29260, n=9, some SEM material), west shore, Cape Bancea, 01°59.023'S, 120°35.108'E, loc. 59-04, on rocks in shallow water, coll. M. Glaubrecht & T. von Rintelen , 29 Mar.2004 ; 1 ex. ( ZMB 29290, n=1 and some juveniles, some SEM material), south shore, Pendolo beach at Hotel Mulia, 02°3.928'S, 120°41.536'E, loc. 157-04, on wood, coll. K . & T. von Rintelen , 15 Aug.2004 ; 8 ex. ( ZMB 29292a, n=2; ZMB 29292b, n=6), east shore, south of Cape Sinampada , 01°56.25'S, 120°40.443'E, loc. 159-04, (a) on rocks in deeper water (approx. 13 m), (b) on macrophytes, coll. M. Glaubrecht & T. von Rintelen , 29 Mar.2004 ; 5 ex. ( ZMB 29306), east shore, Tando Bone , 01°50.0'S, 120°38.004'E, loc. 157-05, on wood, coll. K. von Rintelen, 3 Oct.2005 ; 13 ex. ( MZB Cru 1720, n=6; ZMB 29325, n=7), west shore, Siuri, 01°48.259'S, 120°31.667'E, loc. 186-05, on mixed substrate, coll. K. von Rintelen, 6 Oct.2005 ; 4 ex. ( ZMB 29382), north shore, 01°47.162'S, 120°33.144'E, loc. 187-05, on rocks, coll. K. von Rintelen, 6 Oct.2005 ; 6 ex. ( ZMB 29385), west shore, 02°2.734'S, 120°37.368'E, loc. 178-05, on wood, coll. K. von Rintelen, 6 Oct.2005 ; 4 ex. ( ZMB 29393), east shore, at road Tentena-Peura , 01°47.33'S, 120°38.079'E, loc. 160-05, on wood, coll. K. von Rintelen, 3 Oct.2005 ; 8 ex. ( MZB Cru 1721, n=4; ZMB 29394, n=4), west shore, 01°58.21'S, 120°34.316'E, loc. 181-05, on wood, coll. K. von Rintelen, 6 Oct.2005 ; 13 ex. ( MZB Cru 1722, n=6; ZMB 29395, n=7, some SEM material), east shore, bay at Cape Nceppo, 01°52.39'S, 120°38.974'E, loc. 156-05, on mixed substrate, coll. K. von Rintelen, 3 Oct.2005 ; 7 ex. ( MZB Cru 1723, n=3; ZMB 29400, n=4), east shore, shallow bay at Cape Songuo, 01°53.748'S, 120°39.939'E, loc. 155-05, on mixed substrate, coll . R. Lamers & K. von Rintelen, 3 Oct.2005 ; 1 ex. ( ZMB 29405), west shore, Taipa , 01°55.289'S, 120°32.77'E, loc. 182-05, on wood, coll. K. von Rintelen, 6 Oct.2005 .

Description. – Carapace length 3.0- 4.5 mm (n=40). Rostrum ( Fig. 52A ; Tables 19 -20) very long and slender, reaching far beyond end of scaphocerite, 1.9-2.6 times as long as carapace (n=40), armed dorsally with 11-20 teeth (including 2-4 teeth posterior to orbital margin), approx. anterior 2/3 unarmed, without subapical teeth, armed ventrally with 26-48 teeth. Antennal spine situated below inferior orbital angle. Pterygostomial angle broadly rounded. Eyes well developed, anterior end 0.5-0.6 times length of basal segment of antennular peduncle (n=5). Antennular peduncle 0.9-1.1 times as long as carapace (n=5), second segment 1.8-2.0 times length of third segment, third segment 0.3 times length of basal segment. Stylocerite reaching 0.8-1.0 times length of basal segment of antennular peduncle (n=5). Scaphocerite ( Fig. 52D ) 3.6-4.8 times as long as wide (n=5).

Sixth abdominal somite 0.4-0.8 times length of carapace (n=40), 1.0-2.5 times as long as fifth somite(n=40), 0.9-1.0 times length of telson (n=5). Telson ( Fig. 52C,J ) 3.5-4.1 times as long as wide (n=5), distal margin rounded, without projection, with 4-5 pairs of spinules and 1 pair of dorsolateral spinules; distal end with 2-3 pairs of spines, lateral pair distinctly longer than intermediate pairs. Preanal carina ( Fig. 52E ) with a spine. Uropodal diaeresis ( Fig. 52B ) with 11-14 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. Epipods present on first two pereiopods. Incisor process of mandible ( Fig. 53A ) ending in a row of 3-4 small teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 53B ) broadly rounded, upper lacinia elongate, with numerous distinct teeth and setae on inner margin, palp slender. Upper endites of maxilla ( Fig. 53C ) subdivided, palp short, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Distal end of palp of first maxilliped ( Fig. 53F ) triangular, ending with a short finger-like projection; flagellum of the exopod short and stout, endopod high, almost reaching end of the flagellum of exopod. Second maxilliped ( Fig. 53E ) typical. Third maxilliped ( Fig. 53D ) with ultimate segment as long as penultimate segment.

Chela and carpus of first pereiopod distinctly stouter and broader than chela and carpus of second pereiopod ( Fig. 52 K-M); chela of first pereiopod 1.9-2.7 times as long as wide (n=40), 0.9-1.5 times length of carpus (n=40); tips of fingers rounded, without hooks; dactylus 1.1-1.4 times as long as palm (n=5); carpus 1.9-5.1 times as long as wide (n=40), 1.1-1.3 times length of merus (n=5). Chela of second pereiopod 2.1-3.2 times as long as wide (n=40), 0.6-1.4 times length of carpus (n=40); tips of fingers rounded, without hooks, dactylus 1.3-1.6 times as long as palm (n=5); carpus 2.2-6.0 times as long as wide (n=40), 1.3-1.6 times as long as merus (n=5).

Third pereiopod ( Fig. 52F,H ) slender, dactylus 3.0-3.8 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 4-5 accessory spines on flexor margin; propodus 12.9-16.3 times as long as wide, 5.0-6.0 times as long as dactylus; carpus 5.9-8.0 times as long as wide, 0.5-0.6 times as long as propodus, 0.5 times as long as merus; merus 9.4-11.8 times as long as wide, bearing 3-5 strong, movable spines on posterior margin of outer surface.

Fifth pereiopod slender ( Fig. 52G,I ), dactylus 3.6-5.0 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 27- 49 accessory spines on flexor margin; propodus 15.8-22.3 times as long as wide, 4.3-6.0 times as long as dactylus; carpus 6.2-7.2 times as long as wide, 0.5-0.6 times as long as propodus, 0.5-0.6 times as long as merus; merus 8.5-11.3 times as long as wide, bearing 3-5 strong, movable spines on posterior margin of outer surface.

Endopod of male first pleopod ( Fig. 52N ) elongated triangular, 2.1-2.8 times as long as proximally wide (n=5), without appendix interna. Appendix interna of male second pleopod ( Fig. 52O ) 0.8-0.9 times length of appendix masculina (n=5).

Ovigerous females with 16- 32 eggs (n= 2 females); egg size 0.9-1.1 x 0.6-0.7 mm (n=25, eggs with and without eyes).

Distribution. – Endemic to Lake Poso (excluding rivers) and widely distributed within the lake ( Fig. 51A ), although not as abundant as C. ensifera .

Biology and ecology. – C. caerulea was mainly found on hard substrate (wood, rocks, but also sporadically on soft substrate, for example macrophytes; compare von Rintelen et al., 2007a).

Colour pattern. – Body transparently yellowish or reddish, antennules reddish; legs and rostrum bluish ( Fig. 51B ). The most conspicuous pattern is visible on the tailfan, each endopod bearing an elongated blue patch (upside down Vshape) on the distal part ( Fig. 51C ).

Etymology. – The name Caridina caerulea refers to the conspicuous colour pattern of this new species (the Latin word caeruleus means blue). C. caerulea is the only ancient lake shrimp exhibiting a partly blue body colouration.

Taxonomic remarks. – Of all Lake Poso species, C. caerulea closely resembles C. ensifera . Therefore, both taxa can easily be confused as alcohol bleached material, although in living specimens the colour pattern (“blue” vs. “red” in C. ensifera ; compare von Rintelen et al. 2007a) always allows an unambiguous separation, even in juveniles. Additionally, they show different substrate preferences and behaviour (rather stationary on hard substrate, i.e. rock and wood, vs. often pelagic on various kinds of substrate in C. ensifera ). Although C. caerulea is almost identical with C. ensifera (excluding the always distinct colour pattern), it can be distinguished by not only a generally higher number of rostral teeth (Table 20), but also by a higher number of spines on the uropodal diaeresis (11-14, median 12 vs. 9-11, median 10 in C. ensifera ) and by a lower number of spines on the third and fifth pereiopod (4-5, median 5 and 27-49, median 35 vs. 6-9, median 6 and 51-57, median 52 in C. ensifera ).

The morphological results are well supported by molecular data (Figs. 63,65), placing C. caerulea and C. ensifera in two separate clades that are not even sister groups (for a detailed discussion see von Rintelen et al., 2007a).

Figures

Fig. 51. Caridina caerulea from Lake Poso. A. Distribution. B-C. Colour pattern of living animals (not to scale). Picture B. courtesy of Chris Lukhaup.

Fig. 52. Caridina caerulea from Lake Poso. A. Cephalothorax and cephalic appendages, male (ZMB 29251); B. Uropodal diaeresis; C. Telson, female (ZMB 29251); D. Scaphocerite, female (ZMB 29393); E. Preanal carina, F. Dactylus of third pereiopod, male (ZMB 29395); G. Dactylus of fifth pereiopod; H. Third pereiopod; I. Fifth pereiopod; J. Distal end of telson, female (ZMB 29251); K. SEM image of chela and carpus of first and second pereiopods, female (ZMB 29251); L. First pereiopod, male (ZMB 29260); M. Second pereiopod; N. Endopod of male first pleopod (ZMB 29393); O. Appendix masculina of male second pleopod. Scale bars: A, D = 1.0 mm; C, E, H-I, K-O = 0.5 mm; B, F-G, J = 0.1 mm.

Fig. 53. Caridina caerulea from the Lake Poso catchment. A. Mandible (ZMB 29260); 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.