Caridina marlenae 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 marlenae Klotz, Wowor & K. von Rintelen sp. nov. Figures 3G , 9 , 10

Material examined.

Holotype: ♀ cl. 2.8 mm (MZB Cru 5039), Indonesia, Central Sulawesi, Lake Poso, E shore, S of Tentena, dive at small cape, 15 m, 1°46.394'S, 120°38.327'E, T. von Rintelen and W. Klotz leg., 12 May 2017. Paratypes: 4 ♀♀ cl. 1.4-2.1 mm, 1 ♂ cl. 1.6 mm (MZB Cru 5040), 1 ♀ cl. 2.3 mm, 3 ♂♂ cl. 2.0-2.2 mm (ZMB 30199), same data as holotype; 2 ov. ♀♀ cl. 2.7 and 2.8 mm, 2 ♂♂ cl. 2.5 and 2.8 mm (MZB Cru 5041), 2 ♀♀ cl. 2.6 and 3.1 mm, 1 ♂ cl. 2.4 mm, 2 sequenced specimens without anterior pleopods cl. 2.2 and 2.9 mm (ZMB 29519), Lake Poso, E shore, S of Tentena, dive at small cape, in 15 m depth, 1°46.394'S, 120°38.327'E, M. Glaubrecht and T. von Rintelen leg., 16 May 2007; 2 ♀♀ cl. 2.1 and 2.5 mm, 1 ♂ cl. 2.0 mm, 2 juv. specimens (MZB Cru 5092), 2 ♀♀ cl. 1.9 and 2.2 mm, 1 ♂ cl. 1.8 mm, 1 juv. specimen (ZMB 31661), Lake Poso, E shore, S of Tentena, dive at small cape, in 15 m depth, 1°46.394'S, 120°38.327'E, T. von Rintelen leg., 14 Jul 2019.

Comparative material examined.

Caridina sarasinorum Schenkel, 1902, 1 ov. ♀ cl. 3.0 mm, 1 ♂ cl. 2.6 mm (ZMB 29288), Lake Poso, E shore, 2°0.825'S, 120°42.007'E, K. Zitzler leg., 16 Aug. 2004; 2 ov. ♀♀ cl. 3.2 and 3.6 mm, 1 ♀ cl. 3.mm, 5 ♂♂ cl. 2.1-2.6 mm, 2 juv. specimens cl. 1.7 mm, 1 damaged specimen cl. 2.0 mm (ZMB 30224), Lake Poso, E shore, beach in front of Dolidi Ndano Cottages, 1°48.14'S, 120°38.043'E, W. Klotz leg., 12 May 2017.

Description.

Cephalothorax and cephalic appendages. Postorbital carapace length 1.44-3.07 mm (n = 19). Rostrum (Fig. 9A, B ) long and slender, curved upwards or sigmoid, reaching slightly beyond end of scaphocerite or in small specimen, to end of the antennular peduncle, distal 0.16-0.40 (median 0.38, n = 11) of dorsal margin unarmed, ventral margin armed throughout, dorsal teeth more widely spaced distally, 0.95-1.54 (median 1.20, n = 14) times as long as carapace, rostral formula 3-6 (4-6) + 10-20 / 6-18. Antennal spine slightly separated from orbital margin. Pterygostomial angle broadly rounded. Eyes well developed with globular cornea. Antennular peduncle (Fig. 9A, B, G ), 0.89-1.04 (median 0.96, n = 5) times as long as carapace, first segment 1.56-1.79 (median 1.71, n = 4) times as long as second segment, second segment 2.40-2.80 (median 2.58, n = 4) times longer than third segment. Tooth on distolateral margin of first segment of antennular peduncle acute. Stylocerite reaching to 0.78-0.83 (median 0.80, n = 4) of first segment of antennular peduncle. Scaphocerite (Fig. 9H ) 4.10-4.25 (median 4.20, n = 3) times as long as wide.

Abdominal somites, telson and uropods. Sixth abdominal somite 0.55-0.64 (median 0.62, n = 5) times carapace length, 1.93-2.23 (median 2.15, n = 5) times as long as fifth somite, 1.00-1.13 (median 1.12, n = 4) times as long as telson. Distal margin of telson (Fig. 9E, F ) convex or subtriangular without a median projection, with 3-5 pairs of short spiniform setae dorsally and one pair of short spiniform setae dorsolaterally; distal end with 7-10 long spiniform setae, lateral pair slightly longer than others, innermost pair very tiny. Preanal carina (Fig. 9C ) with a hook-like spine. Uropodal diaeresis (Fig. 9D ) with 11-14 stout movable spiniform setae, outermost ones shorter than lateral angle.

Mouthparts and branchiae. Incisor process of mandible (Fig. 9I ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula (Fig. 9J ) 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. 9K ) subdivided, palp slender, scaphognathite tapering posteriorly, fringed with long, curved setae at posterior margin. Palp of first maxilliped (Fig. 10A, B ) ending in triangular shape. Podobranch on second maxilliped (Fig. 10C ) reduced to a lamina. Third maxilliped (Fig. 10D ) with one well developed and one small arthrobranch, ultimate segment of maxilliped shorter than penultimate segment. First pereiopod with an arthrobranch. Pleurobranchs present on all pereiopods. Epipod slightly reduced (without distal hook) on third maxilliped, absent from all pereiopods.

Pereiopods . Chelae of first and second pereiopod (Fig. 10E, F ) well developed; chela of first pereiopod 3.00-3.83 (median 3.20, n = 5) times as long as wide, 1.00-1.05 (median 1.03, n = 5) times length of carpus; tips of fingers (Fig. 10E ) rounded, without hooks, with tufts of hairs near tip; dactylus 1.88-2.50 (median 2.00, n = 5) times as long as palm; carpus slender, hardly excavated distally, 3.85-4.77 (median 4.00, n = 5) times as long as wide, 1.25-1.33 (median 1.29, n = 5) times length of merus. Merus 3.80-4.25 (median 4.00, n = 5) times as long as wide, 0.89-0.95 (median 0.92, n = 4) times as long as ischium. Chela of second pereiopod 3.69-4.38 (median 3.71, n = 5) times as long as wide, 0.68-0.79 (median 0.71, n = 6) times length of carpus; tips of fingers rounded, without hooks, with tufts of hairs near tip; dactylus 1.80-2.25 (median 2.00, n = 5) times as long as palm; carpus 6.78-9.80 (median 7.60, n = 5) times as long as wide, 1.27-1.58 (median 1.47, n = 4) times as long as merus; merus 5.33-6.50 (median 6.00, n = 4) times as long as wide, 0.82-0.93 (median 0.86, n = 4) times as long as ischium. Third pereiopod (Fig. 10G, H ) not sexually dimorphic, dactylus 4.40-5.33 (median 4.50, n = 5) times as long as wide (terminal claw and spiniform setae on flexor margin included), terminating in one large claw with four or five short spiniform setae on flexor margin; propodus slender, 13.67-16.25 (median 14.57, n = 5) times as long as wide, 3.56-4.06 (median 3.78, n = 5) times as long as dactylus; carpus bearing one strong and 6 small short spiniform setae on posterior margin of outer surface, 7.50-8.36 (median 8.00, n = 5) times as long as wide, 0.63-0.75 (median 0.68, n = 5) times as long as propodus; merus slender, 10.36-12.62 (median 11.60, n = 5) times as long as wide, 1.68-1.93 (median 1.78, n = 5) times as long as carpus, bearing 3-5 strong spiniform setae on posterior margin of outer surface. Ischium with one spiniform seta. Fifth pereiopod (Fig. 10I, J ) slender, dactylus 3.50-4.86 (median 4.13, n = 4) times as long as wide (terminal claw and serrate setae on flexor margin included), terminating in one large claw with 24-31 serrate setae on flexor margin; propodus slender, 13.43-16.00 (median 14.00, n = 4) times as long as wide, 3.29-3.50 (median 3.33, n = 4) times length of dactylus, carpus bearing one strong and 5-7 small spiniform setae on posterior margin of outer surface, 7.57-9.00 (median 7.88, n = 4) times as long as wide, 0.55-0.64 (median 0.57, n = 4) times as long as propodus, 0.63-0.70 (median 0.66, n = 4) times as long as merus; merus slender, 9.20-10.67 (median 10.55, n = 4) times as long as wide, 1.44-1.53 (median 1.51, n = 4) times length of carpus, bearing three or four strong spiniform setae on posterior margin of outer surface. Ischium without a strong spiniform seta.

Pleopods. Endopod of male first pleopod (Fig. 10K ) subtriangular, without an appendix interna, two pappose setae on outer, ~ eight on inner margin, 1.91-2.57 (median 2.00, n = 3) times as long as proximal width, 0.29-0.41 (median 0.29, n = 3) times as long as exopod. Appendix masculina on male second pleopod (Fig. 10L ) rod-shaped, 6.00-8.40 (median 6.00, n = 3) times as long as wide, with long spiniform setae on inner and distal margin, few pappose setae on basal part, appendix interna reaching to ~ 0.72-0.80 (median 0.80, n = 3) of appendix masculina.

Colouration.

Body colouration bright reddish with large white dots (Fig. 3G ).

Reproductive biology and larval development.

Ovigerous females with few eggs (9, n = 1). Size of eggs 0.81-0.83 × 0.48-0.0.51 mm (n = 2).

Etymology.

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

Distribution.

Caridina marlenae sp. nov. is endemic to Lake Poso. Specimens were found only at one locality in a bay south of the town of Tentena at the east shore of the lake.

Ecology.

Caridina marlenae sp. nov. is found under rocks in deep water (more than 5 m).

Remarks.

With its long rostrum, approximately anterior 0.4 unarmed, C. marlenae sp. nov. is similar to C. sarasinorum , C. schenkeli and C. longidigita , all endemic to Lake Poso. In the field, body colouration alone is sufficient to differ C. marlenae sp. nov. from C. sarasinorum or C. schenkeli but it might be confused with reddish specimens of C. longidigita . Caridina marlenae sp. nov. is showing large bright white dots on reddish colouration of the entire body. In C. sarasinorum , the body is coloured dark brown with faint light transversal bands on first, third, fifth and sixth abdominal segments (W. Klotz, pers. observation on the comparative material listed above). In C. schenkeli the colouration of the body is mostly transparent with some brownish or whitish blotches.

In preserved condition, C. marlenae sp. nov. can be distinguished from C. sarasinorum by the more reduced epipods (slightly reduced on the third maxilliped, absent from all pereiopods vs. well developed (with distal hooks) on the third maxilliped and first pereiopod in C. sarasinorum and the slender chelipeds and pereiopods (in detail: chela of first pereiopod 3.00-3.83 times as long as wide vs. 1.74-2.1 times in C. sarasinorum , 1.00-1.05 times as long as carpus vs. 1.35-1.48 times in C. sarasinorum , dactylus 1.88-2.50 times as long as palm vs. 0.83-1.05 times as long in C. sarasinorum , carpus 3.85-4.77 times as long as wide vs. 1.75-2.22 times in C. sarasinorum , merus 3.80-4.25 times as long as wide vs. 1.78-2.63 times in C. sarasinorum . Chela of second pereiopod 3.69-4.38 times as long as wide vs. 2.19-2.64 times in C. sarasinorum , dactylus 1.80-2.25 times as long as palm vs. 1.05-1.33 times as long in C. sarasinorum , carpus 6.78-9.80 times as long as wide vs. 4.56-5.05 times in C. sarasinorum , merus 5.33-6.50 times as long as wide vs. 3.60-4.29 times in C. sarasinorum . Dactylus of third pereiopod 4.40-5.33 times as long as wide vs. 4.0-4.20 in C. sarasinorum , propodus 13.67-16.25 times as long as wide vs. 10.00-11.11 in C. sarasinorum , 3.56-4.06 times as long as dactylus vs. 2.86-3.13 times as long as dactylus in C. sarasinorum . Propodus of fifth pereiopod 13.43-16.00 times as long as wide vs. 10.00-12.00 in C. sarasinorum ).

Caridina marlenae sp. nov. can be distinguished from C. schenkeli by the more reduced epipods (slightly reduced on the third maxilliped, absent from all pereiopods vs. well developed (with distal hooks) on the third maxilliped and first and second pereiopod in C. schenkeli and the slender chelipeds and armature of the dactyli of pereiopods (in detail: chela of first pereiopod 3.00-3.83 times as long as wide vs. 1.90-3.2 times in C. schenkeli , dactylus 1.88-2.50 times as long as palm vs. 1.0-1.4 times as long in C. schenkeli . Carpus of first cheliped 3.85-4.77 times as long as wide vs. 2.1-3.2 times as long as wide in C. schenkeli . Dactylus of second pereiopod 1.80-2.25 times as long as palm vs. 1.2-1.4 times as long in C. schenkeli , carpus 6.78-9.80 times as long as wide vs. 4.5-6.5 times in C. schenkeli . Dactylus of third pereiopod with four or five spiniform setae on flexor margin vs. with 6-8 spiniform setae in C. schenkeli . Dactylus of fifth pereiopod with 24-31 serrate setae on flexor margin vs. with 57-64 in C. schenkeli .

Caridina marlenae sp. nov. can also be distinguished from C. longidigita by the type of chelae built for scraping vs. for filter-feeding in C. longidigita (brushes of setae short on tips of fingers of chelipeds vs. setae long, chela of first cheliped 3.00-3.83 times as long as wide vs. 4.6-6.5 times as long as wide in C. longidigita , dactylus 1.88-2.50 times as long as palm vs. 3.6-4.6 times as long in C. longidigita , carpus 3.85-4.77 times as long as wide vs. 4.8-8.1 times in C. longidigita ; chela of second pereiopod 3.69-4.38 times as long as wide vs. 4.8-6.4 times in C. longidigita , dactylus 1.80-2.25 times as long as palm vs. 3.4-3.9 times as long in C. longidigita ).

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 9. Caridina marlenae sp. nov. Morphology 1. Paratype ♂, cl. 2.2 mm, ZMB 30199 A cephalothorax and cephalic appendages B rostrum C preanal carina D uropodal diaeresis E, F telson G antennular peduncle H scaphocerite I mandible K maxilla; paratype ♀, cl. 2.3 mm, ZMB 30199 J maxillula. Scale bars: 1 mm (A-E); 0.5 mm (F-K).

Figure 10. Caridina marlenae sp. nov. Morphology 2. Paratype ♂, cl. 2.2 mm, ZMB 30199 A first maxilliped B palp of first maxilliped C second maxilliped D third maxilliped E first pereiopod F second pereiopod I fifth pereiopod K endopod of male first pleopod L appendix masculina on male second pleopod; paratype ♀, cl. 2.3 mm, ZMB 30199 G third pereiopod H dactylus of third pereiopod J dactylus of fifth pereiopod. Scale bars: 0.5 mm (A, C, H, J-L); 0.1 mm (B); 1 mm (D-G, I).