Caridina ensifera Schenkel, 1902

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 : 432-436

Caridina ensifera Schenkel, 1902

( Figs. 54–55 ; Tables 20–21)

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

Caridina ensifera – Roux, 1904: 552; Bouvier, 1904: 131, 1905: 73, 1912: 918, 1913a: 463; 1913b: 182, 1925: 163, Figs. 344-352; Chace, 1997: 9; Fernandez-Leborans & von Rintelen, 2007; Cai & Wowor, 2007 pro parte: 311, Figs. 1-2 ; von Rintelen et al., 2007a: 1033, Figs. 1-2 ; Tables 1-2, 2008: 2244, Table 1.

Material examined. – Lectotype: male (cl 3.9 mm) ( NHMB 1 a), Indonesia, Sulawesi, Lake Poso , coll. Sarasin, no date indicated.

Paralectotypes – 5 males (cl 3.1-3.5 mm), 10 females (cl 3.0- 5.3 mm) ( NHMB 1 a), same data as lectotype .

Others (Lake Poso): 16 ex. ( MZB Cru 1709, n=8; ZMB 29248, n=8, 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 ; 10 ex. ( MZB Cru 1710, n=5; ZMB 29253, n=5, some SEM material), east shore, Cape Watulunto, 02°0.825'S, 120°42.007'E, loc. 63-04, on mixed substrate, coll. M. Glaubrecht & T. von Rintelen , 30 Mar.2004 ; 5 ex. ( ZMB 29291), east shore, south of Cape Panti , 02°55.277'S, 120°40.289'E, loc. 158-04, on macrophytes, coll. K . & T. von Rintelen , 16 Aug.2004 ; 4 ex. ( ZMB 29381), north shore, 01°47.162'S, 120°33.144'E, loc. 187-05, on rocks, coll. K. von Rintelen, 6 Oct.2005 ; 9 ex. ( MZB Cru 1711, n=4; ZMB 29384, n=5), west shore, Siuri, 01°48.259'S, 120°31.667'E, loc. 186-05, pelagic, coll. K. von Rintelen, 6 Oct.2005 ; 20 ex. ( MZB Cru 1712, n=10; ZMB 29389, n=10, 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 ; 14 ex. ( MZB Cru 1713, n=7; ZMB 29392, n=7), west shore, 02°2.734'S, 120°37.368'E, loc. 178-05, on mixed substrate, coll. K. von Rintelen, 6 Oct.2005 ; 21 ex. ( MZB Cru 1714, n=10; ZMB 29396, n=11), west shore, 01°58.21'S, 120°34.316'E, loc. 181-05, on mixed substrate, coll. K. von Rintelen, 6 Oct.2005 ; 7 ex. ( MZB Cru 1715, n=3; ZMB 29397, n=4), east shore, at road Tentena- Peura, 01°47.33'S, 120°38.079'E, loc. 160-05, on rocks, coll. K. von Rintelen, 3 Oct.2005 ; 8 ex. ( MZB Cru 1716, n=4; ZMB 29399, n=4 and some juveniles), east shore, shallow bay, 01°49.702'S, 120°38.161'E, loc. 159-05, on macrophytes, coll. K. von Rintelen, 3 Oct.2005 ; 17 ex. ( MZB Cru 1717, n=8; ZMB 29404, n=9, some SEM material), west shore, 01°52.205'S, 120°32.281'E, loc. 184-05, pelagic, coll . R. Lamers & K. von Rintelen, 6 Oct.2005 .

Description. – Carapace length 3.5-5.3 mm (n=40). Rostrum ( Fig. 55A ; Tables 20-21) very long and slender, reaching far beyond end of scaphocerite, 1.4-2.3 times as long as carapace (n=40), armed dorsally with 9-15 teeth (including 1-3 teeth posterior to orbital margin), approx. anterior 2/3 unarmed, without subapical teeth, armed ventrally with 16-29 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 1.8-2.2 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. 55B ) 3.6-4.5 times as long as wide (n=5).

Sixth abdominal somite 0.4-0.9 times length of carapace (n=40), 1.0-2.6 times as long as fifth somite (n=40), 1.2-1.3 times length of telson (n=5). Telson ( Fig. 55E,J ) 3.6-4.1 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 2-3 pairs of spines, lateral pair distinctly longer than intermediate spines. Preanal carina ( Fig. 55C ) with a spine. Uropodal diaeresis ( Fig. 55D ) with 9-11 movable spinules (n=5).

5 pairs of pleurobranchs well developed; 3 pairs of arthrobrachs, 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 only present on first two pereiopods. Mouthparts as described by Cai & Wowor (2007).

Chela and carpus of first pereiopod distinctly stouter and broader than chela and carpus of second pereiopod ( Fig. 55 K-M); chela of first pereiopod 2.0-2.8 times as long as wide (n=40), 1.0-1.3 times length of carpus (n=40); tips of fingers rounded, without hooks; dactylus 1.0-1.3 times as long as palm (n=5); carpus 2.5-4.0 times as long as wide (n=40), 1.0-1.3 times length of merus (n=5). Chela of second pereiopod 2.8-4.4 times as long as wide (n=40), 0.7-0.8 times length of carpus (n=40); tips of fingers rounded, without hooks, dactylus 1.2-1.4 times as long as palm (n=5); carpus 5.4-7.3 times as long as wide (n=40), 1.3-1.6 times as long as merus (n=5).

Third pereiopod ( Fig. 55 F-G) slender, dactylus 5.0-5.4 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 6-9 accessory spines on flexor margin; propodus 10.0-13.0 times as long as wide, 3.1-3.7 times as long as dactylus; carpus 4.7-6.1 times as long as wide, 0.5-0.7 times as long as propodus, 0.4-0.5 times as long as merus; merus 9.2-11.4 times as long as wide, bearing 2-4 strong, movable spines on posterior margin of outer surface.

Fifth pereiopod slender ( Fig. 55 H-I), dactylus 5.4-7.0 times as long as wide (terminal spine included, without spines of flexor margin; n=5), terminating in one large claw with 51- 57 accessory spines on flexor margin; propodus 11.1-20.7 times as long as wide, 2.5-3.0 times as long as dactylus; carpus 4.9-5.4 times as long as wide, 0.5 times as long as propodus, 0.5-0.6 times as long as merus; merus 8.8-11.1 times as long as wide, bearing 2-3 strong, movable spines on posterior margin of outer surface.

Endopod of male first pleopod ( Fig. 55N ) elongated triangular, 1.8-2.5 times as long as proximally wide (n=5), without appendix interna. Appendix interna of male second pleopod ( Fig. 55O ) 0.7-0.9 length of appendix masculina (n=5).

Ovigerous females with 19- 25 eggs (n= 2 females); egg size 0.9-1.0 x 0.5-0.6 mm (n=20, eggs with and without eyes).

Distribution. – Endemic to Lake Poso (excluding rivers) and widely distributed within the lake ( Fig. 54A ).

Biology & Ecology. – C. ensifera is a generalist often found in pelagic swarms or sporadically on various kinds of substrate (rocks and wood or soft substrate, for example sand or macrophytes; compare von Rintelen et al., 2007a). It is the most abundant shrimp species in Lake Poso.

Colour pattern. – Body yellowish-transparent with few white or darker dots, antennules reddish ( Fig. 54B ). The most conspicuous pattern is visible on the tailfan, each exopod bearing a red spot on the distal part ( Fig. 54C ).

Taxonomic remarks. – C. ensifera very closely resembles C. caerulea , previously listed as C. ensifera by Cai & Wowor (2007), but discovered as a cryptic species by von Rintelen et al. (2007a). In their revision of the Lake Poso species, Cai & Wowor (2007: 314) describe the colour of C. ensifera as “a single specimen from Lake Poso […] transparent finely spectra, blue-red n-shape on brachiostegal region, blue spot on distal exopod of uropods-conspicuous”. Thus, they describe the colour pattern of C. caerulea , although their data rather hint at C. ensifera sensu Schenkel (1902) . The reason to assign C. ensifera (this study) to the original description of C. ensifera , and to describe C. caerulea as a new species, is mainly based on the rostrum denticulation mentioned in Schenkel’s original description (see Table 20). C. ensifera , as here describe, shows a high congruence with Schenkel’s data (dorsally 9-15 and ventrally 16-29 vs. dorsally 9-20 and ventrally 8-26 in the original description), whereas in C. caerulea the number of ventral teeth (26-48) does not really agree with Schenkel’s description, especially if the median is considered. Other parameters of Schenkel’s description either fit both species (for example the number of spinules and spines of the telson) or are not comparable due to an obviously different technique of measurement (for example the carapace and rostrum length). Another aspect to consider here is that C. ensifera generally has the highest density of all shrimps in Lake Poso and we thus assume it more likely to be caught by the Sarasins than C. caerulea . Although C. ensifera is almost identical with C. caerulea (not counting the always distinct colour pattern), it can not only be distinguished by a generally lower number of rostral teeth (Table 20), but also by a lower number of spines on the uropodal diaeresis (9-11 vs. 11-14 in C. caerulea ) and by a higher number of spines on the third and fifth pereiopod (6-9 and 51-57 vs. 4-5 and 27-49 in C. caerulea ). A disciminant analysis of several morphological characters separates both species a hundred percent (von Rintelen et al. 2007a).

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

Figures

Fig. 54. Caridina ensifera from Lake Poso. A. Distribution. B-C. Colour pattern of living animals (not to scale). Picture B. courtesy of Chris Lukhaup.

Fig. 55. Caridina ensifera from Lake Poso. A. Cephalothorax and cephalic appendages, female (ZMB 29389); B. Scaphocerite, male (ZMB 29404); C. Preanal carina; D. Uropodal diaeresis, female (ZMB 29389); E. Telson, female (ZMB 29248), F. Third pereiopod, female (ZMB 29389); G. Dactylus of third pereiopod; H. Fifth pereiopod; I. Dactylus of fifth pereiopod; J. Distal end of telson, female (ZMB 29248); K. First pereiopod, male (ZMB 29404); L. Second pereiopod; M. SEM image of chela and carpus of first and second pereiopods; N. Endopod of male first pleopod; O. Appendix masculina of male second pleopod. Scale bars: A-B = 1.0 mm; C, E-F, H, J-O = 0.5 mm; D, G, I = 0.1 mm.

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.