Caridina lilianae Klotz, Wowor & K. von Rintelen, 2021

Klotz, Werner, Rintelen, Thomas von, Wowor, Daisy, Lukhaup, Chris & Rintelen, Kristina von, 2021, Lake Poso's shrimp fauna revisited: the description of five new species of the genus Caridina (Crustacea, Decapoda, Atyidae) more than doubles the number of endemic lacustrine species, ZooKeys 1009, pp. 81-122 : 81

Caridina lilianae Klotz, Wowor & K. von Rintelen sp. nov. Figures 3C , 7 , 8

Material examined.

Holotype: ov. ♀ cl. 3.1 mm (MZB Cru 5035), Indonesia, Central Sulawesi, Lake Poso, E shore, S of Tentena, dredge in centre of bay, C. Lukhaup, T. von Rintelen, C. and F. Logemann leg., 17 Jun. 2011. Paratypes: 3 ov. ♀♀ cl. 2.8-2.9 mm (MZB Cru 5036), 2 ov. ♀♀ cl. 2.7 and 3.1 mm, 1 ♀ cl. 2.7 mm, 1 ♂ cl. 2.5 mm (ZMB 29807), same data as holotype; 3 ♀♀ cl. 1.7-2.6 mm, 4 ♂♂ cl. 1.9-2.2 mm (MZB Cru 5037), 1 ov. ♀ cl. 2.4 mm, 2 ♀♀ cl. 1.9 and 2.5 mm, 3 ♂♂ cl. 1.9-2.2 mm (ZMB 30197), Lake Poso, E shore, small bay within mouth of outlet, 1°46.30'S, 120°38.38'E, W. Klotz and T. von Rintelen leg., 12 May 2017; 1 ov. ♀ cl. 2.6 mm, 2 ♀♀ cl. 2.1 and 2,6 mm, 2 ♂♂ cl. 1.8 and 2.4 mm (MZB 5038), 2 ov. ♀♀ cl. 2.5 and 2.7 mm, 2 ♀♀ cl. 2.6 mm, 3 ♂♂ cl. 2.0-3.0 mm (ZMB 30713), Lake Poso, W shore, Bay N of Bancea, in 1.5-3 m depth, 1°58.91'S, 120°34.877'E, T. von Rintelen leg., 04 Aug. 2018; 1 ov. ♀ cl. 2.4 mm, 1 ♀ cl. 2.3 mm (ZMB 30755), 2 ♀♀ cl. 2.1 and 2.3 mm, 1 ♂ cl. 1.9 mm (MZB Cru 5091) Lake Poso: E shore, small bay within mouth of outlet, 1°46.30'S, 120°38.38'E, T. von Rintelen leg., 14 Jul 2019.

Description.

Cephalothorax and cephalic appendages. Postorbital carapace length 1.7-3.1 mm (n = 33). Rostrum (Fig. 7A, B ) very short, not overreaching distal margin of eyes, clearly convex on dorsal margin, abruptly tapering to a fine tip distally, 0.18-0.33 (median 0.26, n = 20) times as long as carapace, rostral formula 5-10 + 5-10 / 0. Antennal spine well separated from inferior orbital angle. Pterygostomial angle subrectangular. Eyes well developed with globular cornea. Antennular peduncle (Fig. 7A, G ), 0.70-0.79 (median 0.75, n = 6) times as long as carapace in females, 0.92 (n = 1) times as long as carapace in male, first segment 2.08-2.70 (median 2.42, n = 7) times as long as second segment, second segment 1.67-2.75 (median 2.50, n = 7) times longer than third segment. Stylocerite reaching to 0.68-0.89 (median 0.77, n = 6) of first segment of antennular peduncle. Scaphocerite (Fig. 7H ) 3.43-4.62 (median 4.02) times as long as wide.

Abdominal somites, telson and uropods. Sixth abdominal somite 0.68-0.88 (median 0.77, n = 6) times carapace length, 1.78-2.26 (median 2.00, n = 6) times as long as fifth somite, 1.08-1.29 (median 1.22, n = 6) times as long as telson. Telson (Fig. 7E, F ) with distal margin rounded or convex without a median projection, with 2-4 pairs of short spiniform setae dorsally and one pair of short spiniform setae dorsolaterally; distal end with 4-8 long spiniform setae, lateral pair shorter than others. Preanal carina (Fig. 7C ) with a distinct hook-like spine. Uropodal diaeresis (Fig. 7D ) with seven or eight stout movable spiniform setae, outermost ones shorter than lateral angle.

Mouthparts and branchiae. Incisor process of mandible (Fig. 7I ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula (Fig. 7J ) ovate, upper lacinia elongate, with numerous distinct teeth on inner margin, palp slender with few pappose setae and one conical spiniform seta near tip. Upper endites of maxilla (Fig. 7K ) subdivided, palp slender, scaphognathite tapering posteriorly, fringed with long, curved setae at posterior margin. Palp of first maxilliped (Fig. 7L, M ) ending in blunt triangular shape. Podobranch on second maxilliped (Fig. 8A ) reduced to a lamina. Third maxilliped (Fig. 8B ) with one well developed and one strongly reduced arthrobranch, ultimate segment slightly shorter than penultimate segment. First pereiopod with an arthrobranch. Pleurobranchs present on all pereiopods. Epipod reduced (without distal hook) on third maxilliped, absent from all pereiopods (a vestigial epipod was seen in one of the specimens examined (Fig. 8C )).

Pereiopods . Chelae of first and second pereiopods (Fig. 8C-F ) rather less developed and conspicuous small; chela of first pereiopod 3.43-4.62 (median 4.02, n = 2) times as long as wide, 0.94-0.96 (median 0.95, n = 2) times length of carpus; tips of fingers rounded, without hooks, with scarce hairs near tip; dactylus 1.50-1.58 (median 1.54, n = 2) times as long as palm; carpus slender, hardly excavated distally, 4.55-5.33 (median 4.94, n = 2) times as long as wide, 1.32-1.33 (median 1.32, n = 2) times length of merus. Merus 3.80-4.00 (median 3.90, n = 2) times as long as wide, as long as ischium, with few stiff simple setae. Chela of second pereiopod 4.31-4.92 (median 4.62, n = 2) times as long as wide, 0.80-0.90 (median 0.85, n = 2) times length of carpus; tips of fingers rounded, without hooks, with scarce hairs near tip; dactylus 1.67-1.80 (median 1.73, n = 2) times as long as palm; carpus 6.20-8.00 (median 7.10, n = 2) times as long as wide, 1.35-1.48 (median 1.41, n = 2) times as long as merus; merus 4.60-4.91 (median 4.75, n = 2) times as long as wide, as long as ischium, merus and ischium with long simple setae. Third pereiopod (Fig. 8G, H ) slender, not sexually dimorphic, dactylus very slender 8.00-10.80 (median 9.40, n = 2) times as long as wide (terminal claw included), terminating in one large claw, without spiniform setae on flexor margin; propodus 7.25-7.56 (median 7.40, n = 2) times as long as wide, 1.26-1.45 (median 1.35, n = 2) times as long as dactylus; carpus 4.22-4.55 (median 4.38, n = 2) times as long as wide, 0.66-0.74 (median 0.70, n = 2) times as long as propodus; merus 6.33-7.43 (median 6.88, n = 2) times as long as wide, 1.31-1.53 (median 1.42, n = 2) times as long as carpus, bearing two strong spiniform setae on posterior margin of outer surface and long stiff simply setae along the entire segment. Ischium without spiniform seta but with long stiff simply setae similar to the setae on merus. Fifth pereiopod (Fig. 8I, J ) slender, dactylus 10.00 times as long as wide (terminal claw and serrate setae on flexor margin included), terminating in one large claw with ~ 19 serrate setae on proximal half of flexor margin; propodus 8.00 times as long as wide, 1.33 times length of dactylus, carpus 4.17 times as long as wide, 0.63 times as long as propodus; merus 6.57 times as long as wide, 1.84 times length of carpus, bearing one strong spiniform seta on posterior margin of outer surface and long stiff simply setae along the entire segment. Ischium without spiniform seta but with long stiff simply setae similar to the setae on merus.

Pleopods. Endopod of male first pleopod (Fig. 8K ) subtriangular, without appendix interna, 2.00-2.22 (n = 2) times as long as proximal width. Appendix masculina on male second pleopod (Fig. 8L ) slender, 7.60-10.33 (n = 2) times as long as wide, with long spiniform setae on inner and distal margin, few pappose setae on basal part, appendix interna reaching to distal margin of appendix masculina or slightly overreaching it.

Colouration.

Body colouration transparent to whitish with minute sand-coloured dots (Fig. 3C ).

Reproductive biology and larval development.

Ovigerous females with few eggs (35, n = 1). Size of undeveloped eggs (early stage embryos without eyespot) 0.61-0.72 × 0.37-0.39 mm, size of developed eggs (late stage embryos with eyes) 0.70-0.76 × 0.39-0.44 mm (n = 6).

Etymology.

Named after the second and last authors’ first daughter who is very interested in field work and helped to observe and document this species while visiting the lake in 2019.

Distribution.

Caridina lilianae sp. nov. is endemic to Lake Poso. Specimens were found at three localities within the lake, two within a bay south of the town of Tentena at the east shore and one in a bay at the west shore.

Ecology.

Caridina lilianae sp. nov. lives on very fine sand or silt (soft substrate) in shallow water (1.5-2.5m).

Remarks.

With its small size and the less developed chelae with scarce setae at the tip of the fingers, C. lilianae sp. nov. is similar to C. mayamareenae sp. nov. but can easily be distinguished from this species by the very short, convex rostrum (vs. rostrum conspicuous high, reaching to end of second segment of antennular peduncle or slightly overreaching this segment) and the slender third pair of pereiopods bearing long stiff setae on merus and ischium but without any spiniform setae on flexor margin (vs. third pereiopod very robust, without long simple setae on merus and ischium and dactylus with five or six spiniform setae on flexor margin). These characters also distinguish C. lilianae sp. nov. from all other Caridina spp. known from the Lake Poso. Although C. lilianae sp. nov. and C. mayamareenae sp. nov. occur in sympatry in the lake, the microhabitats of these species are quite different. Caridina mayamareenae sp. nov. lives in empty shells of aquatic snails while C. lilianae sp. nov. on soft substrate. The long stiff simple setae attached to the posterior segments of the chelipeds and pereiopods could be interpreted as a morphological adaption to this kind of habitat by preventing them to subside into the soft substrate. This hypothesis would need to be tested, though. In the field, the whitish or cream-coloured body colouration is indiscernible on light-coloured sandy habitats (Fig. 3D ).

Figures

Figure 3. Living specimens of Caridina spp in Lake Poso 2. A, B Caridina mayamareenae sp. nov. C C. lilianae sp. nov. D Two snail species Celetaia persculpta and Tylomelania sp. on soft substrate. Empty shells of these species are shelter for C. mayamareenae sp. nov. E, F C. poso sp. nov. G C. marlenae sp. nov. H C. fusca sp. nov. Not to scale. All photographs: W. Klotz.

Figure 7. Caridina lilianae sp. nov. Morphology 1. Paratype ov. ♀, cl. 3.1 mm, ZMB 29807 A cephalothorax and cephalic appendages C preanal carina D uropodal diaeresis G antennular peduncle H scaphocerite I mandible K maxilla L first maxilliped M Palp of first maxilliped; paratype ♂, cl. 2.2 mm, ZMB 30197 B rostrum E, F telson J maxillula. Scale bars: 2 mm (A); 1 mm (B, E); 0.5 mm (C, D, F, M).

Figure 8. Caridina lilianae sp. nov. Morphology 2. Paratype ov. ♀, cl. 3.1 mm, ZMB 29807 A second maxilliped B third maxilliped C first pereiopod D chela of first pereiopod E second pereiopod F chela of second pereiopod G third pereiopod H dactylus of third pereiopod I fifth pereiopod J dactylus of fifth pereiopod; paratype ♂, cl. 2.2 mm, ZMB 30197 K endopod of male first pleopod L appendix masculina on male second pleopod. Scale bars: 1 mm (A-C, E, G, I); 0.5 mm (D, F, H, J-L).