Caridina poso 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 poso Klotz, Wowor & K. von Rintelen sp. nov. Figures 3E-F , 13 , 14

Material examined.

Holotype: ov. ♂ cl. 2.7 mm (MZB Cru 5050), Indonesia, Central Sulawesi, Lake Poso, at Taipa, H-G. Evers leg., 26 Sep. 2010. Paratypes: 2 ov. ♀♀ cl. 2.9 and 3.1 mm, 3 ♀♀ cl. 3.0-3.1 mm, 2 ♂♂ cl. 2.6 and 2.7 mm (ZMB 29624), same data as holotype; 5 ov. ♀♀ cl. 3.2-3.4 mm, 5 ♂♂ cl. 2.7-3.2 mm (MZB Cru 5051), 5 ov. ♀♀ cl. 3.3-3.8 mm, 2 ♂♂ cl. 3.1 and 3.2 mm (ZMB 29621), Lake Poso, E shore, "Sulawesi Rock", 1°56.102'S, 120°40.402'E, J. Pfaender and T. von Rintelen leg., 22 Sep. 2015; 5 ♂♂ cl. 2.4-2.7 mm (MZB Cru 5052), 1 ov. ♀ cl. 3.1 mm, 4 ♂♂ cl. 2.6-2.9 mm (ZMB 28063), Lake Poso, W shore, 1°56.67'S, 120°33.925'E, B. Stelbrink leg., 07 Sep. 2012.

Other material: 1 ♂ cl. 2.7 mm (ZMB 29766), aquarium reared specimen, preserved on 08 Oct. 2015 by W. Klotz.

Description.

Cephalothorax and cephalic appendages. Postorbital carapace length 2.6-3.8 mm (n = 36). Rostrum (Fig. 13A-C ) very long and slender, curved upwards, reaching far beyond end of scaphocerite, distal 0.5 to 0.8 unarmed, ventral margin armed throughout, most proximal tooth placed below third tooth of dorsal margin in most specimens, 1.35-2.75 (median 2.01, n = 23) times as long as carapace, rostral formula 3-5(4) + 8-14 / 19-37. Orbital margin fused with an antennal spine. Pterygostomial angle broadly rounded. Eyes well developed with globular cornea. Antennular peduncle (Fig. 13A, C ), 0.97-1.03 (median 1.01, n = 4) times as long as carapace in females, 1.07-1.19 (median 1.16, n = 4) times as long as carapace in males, first segment 1.48-1.78 (median 1.55, n = 5) times as long as second segment, second segment 2.25-2.88 (median 2.44, n = 5) times longer than third segment. Stylocerite reaching to 0.78-0.88 (median 0.83, n = 4) of first segment of antennular peduncle. Scaphocerite (Fig. 13H ) 4.30-5.33 (median 4.75, n = 6) times as long as wide.

Abdominal somites, telson and uropods. Sixth abdominal somite 0.60-0.76 (median 0.67, n = 12) times carapace length, 1.70-2.18 (median 1.95, n = 11) times as long as fifth somite, 0.93-1.11 (median 1.08, n = 9) times as long as telson. Telson (Fig. 13F, G ) 3.19-3.83 (median 3.50, n = 3) times as long as proximal wide, 5.73-6.42 (median 6.13, n = 3) times as long as distal wide, distal margin convex without a median projection, with three or four pairs of short spiniform setae dorsally and one pair of short spiniform setae dorsolaterally; distal end with 6-8 long spiniform setae, lateral pair slightly longer than others, innermost pair very tiny. Preanal carina (Fig. 13D ) with a hook-like spine. Uropodal diaeresis (Fig. 13E ) with 10-12 short movable spiniform setae, outermost ones shorter than lateral angle.

Mouthparts and branchiae. Incisor process of mandible (Fig. 13I ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula (Fig. 13J ) broadly rounded, 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. 13K ) subdivided, palp slender, scaphognathite tapering posteriorly, fringed with long, curved setae at posterior margin. End of palp of first maxilliped triangular (Fig. 13L, M ). Podobranch on second maxilliped (Fig. 14A ) reduced to a lamina. Third maxilliped (Fig. 14B ) with two arthrobranchs, ultimate segment of maxilliped shorter than penultimate segment. First pereiopod with an arthrobranch. Pleurobranchs present on all pereiopods. Epipod vestigial on third maxilliped, absent from all pereiopods.

Pereiopods . Chelae of first and second pereiopods (Fig. 14C, D ) well developed; chela of first pereiopod 3.11-3.36 (median 3.13, n = 5) times as long as wide, 0.95-1.21 (median 1.13, n = 5) times length of carpus; tips of fingers (Fig. 14C ) rounded, without hooks, with tufts of hairs near tip; dactylus 2.00-2.50 (median 2.00, n = 5) times as long as palm; carpus slender, hardly excavated distally, 3.13-4.33 (median 3.76, n = 5) times as long as wide, 1.29-1.56 (median 1.45, n = 5) times length of merus. Merus 3.13-3.63 (median 3.38, n = 5) times as long as wide, 0.81-0.88 (median 0.85, n = 5) times as long as ischium. Chela of second pereiopod 3.23-3.91 (median 3.71, n = 6) times as long as wide, 0.67-0.84 (median 0.76, n = 6) times length of carpus; tips of fingers rounded, without hooks, with tufts of hairs near tip; dactylus 1.47-2.29 (median 2.00, n = 6) times as long as palm; carpus 6.50-8.38 (median 7.29, n = 6) times as long as wide, 1.38-1.63 (median 1.53, n = 6) times as long as merus; merus 5.08-6.43 (median 5.71, n = 6) times as long as wide, 0.86-0.96 (median 0.87, n = 6) times as long as ischium. Third pereiopod (Fig. 14E, F ) not sexually dimorphic, dactylus 3.11-4.67 (median 3.86, n = 5) times as long as wide (terminal claw and spiniform setae on flexor margin included), terminating in one large claw with 5-7 short spiniform setae on flexor margin; propodus very slender, 16.50-19.11 (median 18.71, n = 6) times as long as wide, 4.78-6.00 (median 5.12, n = 6) times as long as dactylus; carpus 8.73-10.40 (median 9.50, n = 6) times as long as wide, 0.64-0.72 (median 0.70, n = 6) times as long as propodus; merus slender, 11.25-13.93 (median 12.31, n = 6) times as long as wide, 1.54-1.71 (median 1.66, n = 6) times as long as carpus, bearing 4 strong spiniform setae on posterior margin of outer surface. Ischium with one spiniform seta. Fifth pereiopod (Fig. 14G, H ) slender, dactylus 2.43-4.67 (median 3.69, n = 6) times as long as wide (terminal claw and serrate setae on flexor margin included), terminating in one large claw, with 30-34 serrate setae on flexor margin; propodus slender, 15.80-21.50 (median 16.97, n = 6) times as long as wide, 4.41-5.28 (median 4.73, n = 6) times length of dactylus, carpus 7.27-10.40 (median 8.30, n = 6) times as long as wide, 0.51-0.61 (median 0.59, n = 6) times as long as propodus; merus slender, 11.50-12.92 (median 11.74, n = 6) times as long as wide, 1.35-1.63 (median 1.50, n = 6) times length of carpus, bearing four or five strong spiniform setae on posterior margin of outer surface. Ischium without a strong spiniform seta.

Pleopods. Endopod of male first pleopod (Fig. 14I ) subtriangular, without an appendix interna, 1.77-2.27 (median 1.83, n = 3) times as long as proximal width, 0.21-0.27 (median 0.23, n = 3) times as long as exopod. Appendix masculina on male second pleopod (Fig. 14J ) slender, rod-shaped, 7.25-10.50 (median 7.67, n = 3) times as long as wide, with long spiniform setae on inner and distal margin, a few pappose setae on basal part, appendix interna reaching to ~ 0.65-0.90 (median 0.85, n = 3) of appendix masculina.

Colouration.

Body and legs mottled with reddish and white dots arranged in rows, exopod of uropods with a black and white blotch, antennae dark red, chelae white with red fingers (Fig. 3E, F ).

Reproductive biology and larval development.

Ovigerous females with few, large eggs (5 and 9, n = 2). Size of eggs 0.96-1.11 × 0.56-0.66 mm (n = 9).

Etymology.

The specific name is a noun in apposition after the type locality, Lake Poso.

Distribution.

Caridina poso sp. nov. is endemic to Lake Poso. Specimens were found at three localities within the lake, one at the east shore and two at the west shore.

Ecology.

Caridina poso sp. nov. lives in packs of debris (small to medium-sized stones) close to the shore of the Lake Poso and thus could be considered a hard substrate dweller as defined in von Rintelen and Cai (2009). The species was never found on soft substrates such as dead leaves, wood or water plants.

Remarks.

With its long and upturned rostrum, C. poso sp. nov. is similar to C. ensifera and C. caerulea , two endemic species to Lake Poso. In the field, colouration alone is sufficient to differenciate C. poso sp. nov. from these species. The much smaller species C. poso sp. nov. (carapace length 2.6-3.8 mm) is showing black and white blotches on the exopod of the uropods. In the larger species C. ensifera (cl. 3.5-5.3 mm), a dark red spot is seen on the exopod of the uropods. In C. caerulea (cl. 3.0-4.5 mm), the exopod of the uropods shows an elongate blue blotch ( von Rintelen and Cai 2009).

In preserved condition, C. poso sp. nov. can be distinguished from C. ensifera by the absence of epipods on all pereiopods (a vestigial epipod is present on third maxilliped vs. epipods well developed, with distal hooks on the third maxilliped and first and second pereiopods in C. ensifera ) and by the higher number of postorbital teeth on the rostrum (3-5 (mode 4) vs. 1-3 (mode 2) in C. ensifera ). Further, C. poso sp. nov. differs by its slender chelipeds (chela of first pereiopod 3.1-3.4 times as long as high vs. 2.0-2.8 times in C. ensifera , dactylus of first cheliped 2.0-2.5 times as long as palm vs. 1.0-1.3 times in C. ensifera , dactylus of second cheliped 1.5-2.3 times as long as palm vs. 1.2-1.4 times in C. ensifera ) and slender third pair of pereiopods (propodus 16.5-19.1 times as long as wide vs. 10-13 times in C. ensifera , carpus 8.7-10.4 times as long as wide vs. 4.7-6.1 times in C. ensifera , merus 11.3-13.9 times as long as wide vs. 9.2-11.4 times in C. ensifera ). In contrast, the dactyli of the fifth pereiopods are shorter (dactylus 2.4-4.7 times as long as wide vs. 5.4-7.0 times in C. ensifera , propodus 4.4-5.3 times as long as dactylus vs. 2.5-3.0 times in C. ensifera ). The dactyli of fifth pereiopods are armed with a smaller number of serrate setae on the flexor margin (30-34 vs. 51-57 in C. ensifera ). Caridina poso sp. nov. differs from C. caerulea by the absence of epipods on all pereiopods (a vestigial epipod is present on the third maxilliped) vs. epipods well developed (with distal hooks) on the third maxilliped and first and second pereiopods and the higher number of postorbital teeth on the rostrum (3-5 (mode 4) vs. 2-4 (mode 2)) in C. caerulea ; further by its shorter telson (telson 0.6-0.7 times as long as carapace vs. 0.8 times in C. caerulea ), by the slender chelipeds (chela of first pereiopod 3.1-3.4 times as long as high vs. 1.9-2.7 times in C. caerulea , dactylus of first cheliped 2.0-2.5 times as long as palm vs. 1.1-1.4 times in C. caerulea , carpus of first cheliped 3.1-4.3 times as long as wide vs. 2.1-2.5 times in C. caerulea ; chela of second cheliped 3.2-3.9 times as long as wide vs. 2.1-3.2 times in C. caerulea , dactylus of second cheliped 1.5-2.3 times as long as palm vs. 1.3-1.6 times in C. caerulea , carpus of second cheliped 6.5-8.4 times as long as wide vs. 4.1-5.4 times in C. caerulea ). The third pair of pereiopods is more slender (propodus 16.5-19.1 times as long as wide vs. 12.9-16.3 times in C. caerulea , carpus 8.7-10.4 times as long as wide vs. 5.9-8.0 times in C. caerulea , merus 11.3-13.9 times as long as wide vs. 9.4-11.8 times in C. caerulea ). Merus of fifth pereiopod slender, 11.5-12.9 times as long as wide vs. 8.5-11.3 times in C. caerulea .

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 13. Caridina poso sp. nov. Morphology 1. ♂, cl. 2.7 mm, ZMB 29766 A cephalothorax and cephalic appendages D preanal carina E uropodal diaeresis F, G telson; paratype ♂, cl. 2.7 mm, ZMB 29624 B rostrum H scaphocerite I mandible J maxillula K maxilla L first maxilliped M palp of first maxilliped; paratype ov. ♀, cl. 3.4 mm, MZB Cru 5051 C Rostrum. Scale bars: 1 mm (A-C, F, H, I); 0.5 mm (D, E, G, J-L); 0.1 mm (M).

Figure 14. Caridina poso sp. nov. Morphology 2. Paratype ♂, cl. 2.7 mm, ZMB 29624 A second maxilliped B third maxilliped C first pereiopod D second pereiopod E third pereiopod F dactylus of third pereiopod G fifth pereiopod H dactylus of fifth pereiopod; ♂, cl. 2.7 mm, ZMB 29766 I endopod of male first pleopod J appendix masculina on male second pleopod. Scale bars: 0.5 mm (A, F-J); 1 mm (B-E).