Caridina mayamareenae 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 mayamareenae Klotz, Wowor & K. von Rintelen sp. nov. Figures 2E , 3A-B , 11 , 12

Material examined.

Holotype: ov. ♀ cl. 3.0 mm (MZB Cru 5042), Indonesia, Central Sulawesi, Lake Poso, E shore, S of Tentena, dive at small cape, 15 m, 1°46.394'S, 120°38.327'E, J. Pfaender and T. von Rintelen leg., 21 Sep. 2015. Paratypes: 2 ov. ♀♀ cl. 2.6 and 2.8 mm, 4 ♀♀ cl. 2.3-3.4 mm, 3 ♂♂ cl. 1.7-2.5 mm, 1 juv. cl. 1.5 mm (MZB Cru 5043), same data as holotype; 2 ♂♂ cl. 2.5 and 2.7 mm, 1 ov. ♀ cl. 2.8 mm, 1 incomplete ♀ cl. 2.7 mm (ZMB 29627), Lake Poso, E shore, S of Tentena, dredge in centre of bay, T. von Rintelen, C. Lukhaup and F. Logemann leg., 17 Jun. 2011; 1 ♀ cl. 2.7 mm (MZB Cru 5044), Lake Poso, E shore, "Sulawesi Rock", 1°56.102'S, 120°40.402'E, J. Pfaender and T. von Rintelen leg., 22 Sep. 2015; 4 ♂♂ cl. 2.0-2.3 mm, 1 ov. ♀ cl. 2.9 mm (ZMB 29620), Lake Poso, E shore, beach in front of Dolidi Ndano Cottages, 1°48.14'S, 120°38.043'E, J. Pfaender and T. von Rintelen leg., 22 Sep. 2015; 30 ♂♂ cl. 1.5-2.7 mm, 5 ♀♀ cl. 1.6-2.9 mm, 4 ov. ♀♀ cl. 2.7-3.0 mm, 4 juv. cl. 1.4-1.7 mm (ZMB 30202), 34 ♂♂ cl. 1.5-2.6 mm, 6 ♀♀ cl. 2.0-3.0 mm, 2 ov. ♀♀ cl. 2.5 and 3.1 mm, 7 juv. cl. 1.3-1.6 mm (MZB Cru 5045), Lake Poso, E shore, beach in front of Dolidi Ndano Cottages, dive to 15 m, 1°48.14'S, 120°38.043'E, T. von Rintelen leg., 09 May 2017; 4 ov. ♀♀ cl. 2.8-2.9 mm, 8 ♀♀ cl. 1.8-2.8 mm, 6 ♂♂ cl. 3.6-3.8 mm (ZMB 30709), 4 ov. ♀♀ cl. 2.7-3.0 mm, 5 ♂♂ cl. 1.8-2.2 mm, 8 ♀♀ cl. 1.3-2.3 mm (MZB Cru 5046), Lake Poso, NW shore, westernmost cape, 15 m depth, 1°47.39'S, 120°32.641'E, T. von Rintelen leg., 03 Aug. 2018; 5 ov. ♀♀ cl. 2.8-3.0 mm, 4 ♀♀ cl. 1.5-2.8 mm, 6 ♂♂ cl. 1.9-2.1 mm (ZMB 30710), 5 ov. ♀♀ cl. 2.6-2.7 mm, 3 ♀♀ cl. 1.5-2.7 mm, 7 ♂♂ cl. 1.5-2.0 mm (MZB Cru 5047), Lake Poso, NW shore, westernmost cape, 10 m depth, 1°47.39'S, 120°32.641'E, T. von Rintelen leg., 03 Aug. 2018; 2 ov. ♀♀ cl. 2.6 and 2.7 mm, 5 ♀♀ cl. 2.0-2.6 mm, 5 ♂♂ cl. 1.5-1.8 mm (ZMB 30711), 1 ov. ♀ cl. 2.6 mm, 5 ♀♀ cl. 1.6-2.2 mm, 5 ♂♂ cl. 1.5-2.5 mm (MZB Cru 5048), Lake Poso, W shore, S corner of Siuri bay, 13-14 m depth, 1°48.35'S, 120°31.703'E, T. von Rintelen leg., 03 Aug. 2018; 3 ov. ♀♀ cl. 2.5-2.7 mm, 4 ♀♀ cl. 1.8-3.0 mm (ZMB 30714), 4 ov. ♀♀ cl. 2.2-3.0 mm, 1 ♀ cl. 3.4 mm, 1 carapace sex unknown cl. 2.7 mm (MZB Cru 5049), Lake Poso, W shore, Bay N of Bancea, 15 m depth, 1°58.91'S, 120°34.877'E, T. von Rintelen leg., 04 Aug. 2018. 1 ov. ♀ cl. 2.7 mm (MZB Cru 5093), 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. 1 ♀ cl. 2.5 mm (ZMB 30388), 1 ♂ cl. 1.8 mm (MZB Cru 5097), Lake Poso, E shore, "Sulawesi Rock", 1°56.102'S, 120°40.402'E, T. von Rintelen leg., 21 Sep. 2019.

Description.

Cephalothorax and cephalic appendages. Postorbital carapace length 1.3-3.8 mm (n = 220). Rostrum (Fig. 11A, B ) conspicuously high, straight or slightly convex on dorsal margin, distal part of ventral margin convex, reaching to end of second segment of antennular peduncle or slightly overreaching this segment, ventral teeth placed at convex part close to the tip, 0.66-1.0 (median 0.81, n = 7) times as long as carapace, rostral formula 4-7 (5) + 10-19 (15) / 4-12 (7-9). Small antennal spine well separated from inferior orbital angle. Pterygostomial angle broadly rounded. Eyes well developed with globular cornea. Antennular peduncle (Fig. 11A, G ), 0.72-0.83 (median 0.79, n = 4) times as long as carapace in females, 0.95-1.13 (median 1.09, n = 3) times as long as carapace in males, first segment 1.73-2.17 (median 2.0, n = 3) times as long as second segment, second segment 2.30-2.60 (median 2.50) times longer than third segment. Stylocerite reaching to 0.77-0.80 (median 0.77, n = 4) of first segment of antennular peduncle. Scaphocerite (Fig. 11H ) 3.48-3.64 (median 3.56) times as long as wide.

Abdominal somites, telson and uropods. Sixth abdominal somite 0.46-0.71 (median 0.58, n = 8) times carapace length, 1.65-2.0 (median 1.74, n = 8) times as long as fifth somite, 0.90-1.12 (median 1.04, n = 8) times as long as telson. Telson (Fig. 11E, F ) 2.45-2.64 (n = 2) times as long as proximal wide, distal margin broadly 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 long spiniform setae, lateral pair slightly longer than others. Preanal carina (Fig. 11C ) with a hook-like spine. Uropodal diaeresis (Fig. 11D ) with 11-13 stout movable spiniform setae, outermost ones shorter than lateral angle.

Mouthparts and branchiae. Incisor process of mandible (Fig. 12A ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula (Fig. 12B ) broadly rounded, upper lacinia elongate, with numerous distinct teeth on inner margin, palp slender with few simple setae and one conical spiniform seta near tip. Upper endites of maxilla (Fig. 11I ) subdivided, palp slender, scaphognathite tapering posteriorly, fringed with long, curved setae at posterior margin. End of palp of first maxilliped (Fig. 11J, K ) ending in blunt triangular shape. Podobranch on second maxilliped (Fig. 12C ) reduced to a lamina. Third maxilliped (Fig. 12D ) with one well developed and one arthrobranch reduced to a small worm-like structure. 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. 12E-H ) rather less developed and conspicuous small; chela of first pereiopod 4.00-4.17 (median 4.00, n = 3) times as long as wide, 1.07-1.14 (median 1.07, n = 3) times length of carpus; tips of fingers (Fig. 12E, F ) rounded, without hooks, with scarce hairs near tip; dactylus 1.70-1.74 (median 1.73, n = 3) times as long as palm; carpus hardly excavated distally, 4.31-4.40 (median 4.31, n = 3) times as long as wide, 1.05-1.22 (median 1.22, n = 3) times length of merus. Merus 3.83-5.25 (median 4.18, n = 3) times as long as wide, as long as ischium. Chela of second pereiopod 5.00-5.27 (median 5.14, n = 3) times as long as wide, 0.73-0.81 (median 0.76, n = 3) times length of carpus; tips of fingers rounded, without hooks, with scarce hairs near tip; dactylus 1.47-1.93 (median 1.58, n = 3) times as long as palm; carpus 7.17-8.44 (median 8.17, n = 3) times as long as wide, 1.27-1.40 (median 1.34, n = 3) times as long as merus; merus 5.82-7.50 (median 6.36, n = 3) times as long as wide, as long as ischium. Third pereiopod (Fig. 12I, J ) conspicuous stout, not sexually dimorphic, dactylus 3.40-4.38 (median 4.00, n = 3) times as long as wide (terminal claw and spiniform setae on flexor margin included), terminating in one large claw with five or six short spiniform setae on flexor margin; propodus stout, 5.25-7.80 (median 6.00, n = 3) times as long as wide, 2.10-2.47 (median 2.23, n = 3) times as long as dactylus; carpus 3.52-4.83 (median 3.94, n = 3) times as long as wide, 0.74-0.88 (median 0.85, n = 3) times as long as propodus; merus very stout, 4.67-6.50 (median 5.00, n = 3) times as long as wide, 1.89-2.24 (median 2.11, n = 3) times as long as carpus, bearing three strong spiniform setae on posterior margin of outer surface. Ischium without or with one spiniform seta. Fifth pereiopod (Fig. 12K, L ) slender, dactylus 2.73-5.22 (median 5.00, n = 3) times as long as wide (terminal claw and serrate setae on flexor margin included), terminating in one large claw with 18-36 serrate setae on flexor margin; propodus 8.33-11.11 (median 9.09, n = 3) times as long as wide, 2.13-3.33 (median 2.50, n = 3) times length of dactylus, carpus 4.83-6.00 (median 5.17, n = 3) times as long as wide, 0.54-0.62 (median 0.58, n = 3) times as long as propodus; merus 6.93-10.00 (median 8.67, n = 3) times as long as wide, 1.68-1.85 (median 1.79, n = 3) times length of carpus, bearing 2-4 strong spiniform setae on posterior margin of outer surface. Ischium without a strong spiniform seta.

Pleopods. Endopod of male first pleopod (Fig. 12M ) subtriangular, without an appendix interna, 1.83 times as long as proximal width, 0.28 times as long as exopod. Appendix masculina on male second pleopod (Fig. 12N ) slender, rod-shaped, 7.20 times as long as wide, with long spiniform setae on inner and distal margin, few pappose setae on basal part, appendix interna reaching to ~ 0.94 of appendix masculina.

Colouration.

Body colouration of large females whitish, frequently with broad bright red stripes and blotches, eggs green (Fig. 3A, B ), males mostly transparent with some white blotches (Fig. 2E ).

Reproductive biology and larval development.

Ovigerous females with few eggs (36, n = 1). Size of undeveloped eggs (early stage embryos without eyespot) 0.71-0.78 × 0.39-0.54 mm, size of developed eggs (late stage embryos with eyes) 0.78 × 0.47 mm (n = 9).

Etymology.

Named after the fourth author's, daughter for her strong interest in decapod crustaceans her father is working on.

Distribution.

Caridina mayamareenae sp. nov. is endemic to Lake Poso. Specimens were found at five localities within the lake, three in the northern part and two at the eastern and western shores in the southern part of the lake.

Ecology.

Caridina mayamareenae sp. nov. is hiding inside empty shells of the viviparid snail Celetaia persculpta (P. Sarasin and F. Sarasin, 1898) and Tylomelania spp. (Fig. 3D ), and was not observed on any other substrate. On average, 1.4 shrimps were found per shell, but there is considerable variation (0.6-2.4 shrimps per shell) among the examined sites (Table 2 ). Up to four specimens were found in a single shell at the Dolidi Ndano locality. Caridina mayamareenae sp. nov. is also confined to deeper water; shells from depths of 7 m upwards did not contain any shrimps.

Remarks.

Among all species of the genus Caridina known from Lake Poso, C. mayamareenae sp. nov. is unique by its short and conspicuous high rostrum, the less developed chelipeds with scarce setae at the tip of the fingers, and the strong third pair of pereiopods. A high and rather short rostrum is an infrequent character among lacustrine species of the genus Caridina from the Central Lakes of Sulawesi (compare revision in von Rintelen and Cai 2009). Many lacustrine species are showing slender, styliform rostrum shapes as seen in C. ensifera and C. caerulea , the most common species in Lake Poso. The conspicuous high rostrum and the strong third pair of pereiopods adapted for clinging on hard substrate are visible characters of a high grade of specialisation to the microhabitat of this species.

Figures

Figure 2. Living specimens of Caridina spp in Lake Poso 1. A Caridina schenkeli von Rintelen & Cai, 2009 B C. acutirostris Schenkel, 1902 C C. caerulea von Rintelen & Cai, 2009 D C. ensifera Schenkel, 1902 E C. mayamareenae sp. nov. male F, G C. longidigita Cai & Wowor, 2007 H C. sarasinorum Schenkel, 1902. Not to scale. Photo: C. Lukhaup (A, C), W. Klotz (B, D-H).

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 11. Caridina mayamareenae sp. nov. Morphology 1. Paratype ♂, cl. 2.7 mm, ZMB 29627 A cephalothorax and cephalic appendages C preanal carina D uropodal diaeresis E-F telson G antennular peduncle H scaphocerite I maxilla J first maxilliped K palp of first maxilliped; paratype ♀, cl. 2.7 mm, MZB Cru 5044 B rostrum. Scale bars: 2 mm (A, E); 1 mm (B, G-I); 0.5 mm (C, D, F, J, K).

Figure 12. Caridina mayamareenae sp. nov. Morphology 2. Paratype ♂, cl. 2.7 mm, ZMB 29627 A distal part of mandible B maxillula C second maxilliped D third maxilliped E first pereiopod F dactyli of first pereiopod I third pereiopod J dactylus of third pereiopod K fifth pereiopod L dactylus of fifth pereiopod M endopod of male first pleopod N appendix masculina on male second pleopod; paratype ♀, cl. 2.7 mm, MZB Cru 5044 G second pereiopod H dactyli of second pereiopod. Scale bars: 0.5 mm (A-C, F, H, J, L-N); 1 mm (D, E, G, I, K).