Caridina magnovis, Klotz & von Rintelen & von Rintelen, 2024

Klotz, Werner, von Rintelen, Thomas & von Rintelen, Kristina, 2024, Three New Species of the Freshwater Shrimp Genus Caridina from Australia, Arthropoda 2 (1), pp. 99-118 : 106-110

Caridina magnovis n. sp.

Caridina sp. WA 4 Page, von Rintelen and Hughes 2007;

Caridina sp. ‘WA 4’ Wilson, 2008;

Caridina sp. WA 4 Cook, Page and Hughes 2011;

Caridina ‘sp. WA4’ Short, Page and Humphrey, 2019;

( Figures 3 and 4 ).

3.4. Material Examined

Holotype: ♂ cl 2.9 mm, Australia, Western Australia, Fitzroy River catchment, Calder Yard , FIT12-6, leg. M. Scanlon 29.04.1998, WAM C81392 .

Paratypes: One ♂ cl 2.6 mm, one ♀ cl 3.7 mm, same data as holotype WAM C81393 ; one ♂ cl 2.7 mm, Australia, Western Australia, Ord River catchment, Mantinea Flats , leg. M. Scanlon 18.09.1998, WAM C81394 ; two ov. ♀♀ cl 4.0 and 4.3 mm, one ♀ cl 3.7 mm, Darwin Area, Howard River, Gunn Pt. Rd Xing , cultured specimens provided by D. Wilson NTM Cr019573 ; three ♀♀ cl 1.8–2.2 mm, two ♂♂ cl 2.3 and 2.4 mm, Fitzroy River catchment, Dimond Gorge , leg. M. Scanlon 14.04.1998 ZMB 33101 ; one ♂ cl 3.0 mm, Darwin Area, Blackmore River , cultured specimens provided by D. Wilson ZMB 33112 ; one ♀ cl 2.1 mm, one ov. ♀ cl. 3.1 mm, four juv. cl 1.6–1.8 mm, Australia, Northern Territory, Top End, Coomalie Creek , S 13 ° 0.884 ′, E 131 ° 7.371 ′, 85-04, leg. N. Brinkmann und T. von Rintelen 28.06.2004, ZMB 29152 ; two ♀♀ cl 2.5 und 2.7 mm, two ov. ♀♀ cl 2.8 und 2.9 mm, Australia, Northern Territory, Howard Springs , S 12 ° 27.345 ′ E 131 ° 3.146 ′, 79-04, leg. M. Glaubrecht, N. Brinkmann, T. von Rintelen 27.06.2004, ZMB 32120 .

3.5. Comparative Material Examined

Lectotype. Caridina serratirostris de Man, 1892 . Ov. ♀ cl 5.0 mm, Bangkalanvir River, Saleyer , RMNH.CRUS.D.57023 . Syntypes. Caridina serratirostris de Man, 1892 . Two ov. ♀♀ cl 4.4 and 4.6 mm, two ♂♂ cl 3.1 and 3.3 mm, Bangkalanvir River, Saleyer , ZMA.CRUS.D.102625 . Four ov. ♀♀ cl 3.3–4.4 mm, two ♀♀ cl 2.4 and 3.5 mm, two ♂♂ cl 2.4 and 2.6 mm, Indonesia, Rivier bij Reo , Flores eil. coll. 1888 .

3.6. Description

Cephalothorax and cephalic appendages: Small shrimp with carapace lengths of 2.1–4.3 mm (median 2.9 mm, n = 16) in apparently adult specimens. Carapace ( Figure 3 A, B ) smooth, antennal spine almost fused with suborbital lobe, pterygostomial angle rounded. Rostrum ( Figure 3 A, B ) extending to end of second segment of antennular peduncle or to distal end of antennular peduncle, 0.53–0.76 (median 0.64, n = 8) times as long as carapace, nearly straight or slightly convex, ending in acute tip; dorsal margin armed with 17–29 teeth over entire length, including 5–8 postorbital; teeth above orbit larger than anterior and posterior teeth, ventral margin with 3–6 teeth located in distal half of rostrum. Rostrum formula based on 12 specimens 5 − 8 + 12 − 24/3 − 6. Eyes ( Figure 3 A, B ) well developed with pigmented globular cornea. Antennular peduncle ( Figure 3 A, B, G ) 0.60–0.71 (median 0.67, n = 9) times as long as carapace in females, 0.91 times as long as carapace in males, first segment 1.69–2.10 (median 2.0, n = 9) times as long as second segment, second segment 2.20–2.75 (median 2.31, n = 8) times as long as third segment; distolateral tooth on first segment short (0.14–0.23 times as long as second segment), well developed; second and third segments unarmed, with few spiniform setae near distal margin. Stylocerite acuminate, reaching to 0.89–1.05 (median 1.00, n = 9) times the length of basal segment of antennular peduncle. Antennal scaphocerite ( Figure 3 H ) with well-developed distolateral tooth, 2.92–3.7 (median 3.14, n = 5) times as long as wide.

Pleon, telson and uropods: Sixth pleomere was 0.44–0.54 (median 0.46, n = 7) times the carapace length, 1.23–1.69 (median 1.55, n = 6) times as long as fifth somite, 0.80–0.89 (median 0.87, n = 5) times as long as telson. Telson ( Figure 3 C, D ) slightly tapering distally, distal margin convex, with a prominent median point, with 4–5 (n = 7) pairs of dorsal short spiniform setae and one pair of short spiniform setae dorsolaterally; distal margin with one pair of strong spiniform setae and 7–9 plumose setae clearly exceeding lateral pair of spiniform setae. Preanal carina ( Figure 3 E ) rounded, high, with a small tooth in 2 of 7 specimens. Uropodal diaeresis ( Figure 3 F ) with 12–15 movable spiniform setae, the outermost shorter than the lateral angle.

Mouthparts and branchiae: Shown in Figure 3I –O and Figure 4A . Similar to Caridina darwin n. sp. except for the incisor process of mandible ( Figure 3 I, J ), comparably well-developed and numerous irregular teeth and palp of first maxilliped ( Figure 3 M, N ) terminates in a triangular extension. Third maxilliped ( Figure 4 A ) was slender, with the last segment of maxilliped slightly shorter than penultimate segment. Branchial apparatus as shown in Table 3 , with one well developed and one reduced arthrobranch on third maxilliped and one arthrobranch on first pereiopod.

Pereiopods: Chela of first pereiopod ( Figure 4 B ) was caridinoid in shape, slender, with well-developed palm, 1.75–2.84 (median 2.21, n = 5) times as long as wide, 0.93–1.17 (median 1.12, n = 5) times as long as carpus; fingertips rounded, without hooks but each with a tuft of setae; dactylus 2.73–4.25 (median 3.57, n = 5) times as long as wide, 1.00–1.64 (median 1.25, n = 5) times as long as palm. Carpus slender, hardly excavated distally, 2.12–3.22 (median 2.78, n = 5) times as long as wide, 1.09–1.25 (median 1.17, n = 5) times as long as merus. Merus not inflated, 2.75–4.33 (median 3.00, n = 0) times as long as wide, 0.95–1.18 (median 1.0, n = 5) times as long as ischium. Chela of second pereiopod ( Figure 4 C ) very slender, caridinoid in shape, with well-developed palm, 2.75–4.40 (median 3.30, n = 5) times as long as wide, 0.66–0.71 (median 0.69, n = 5) times as long as carpus; fingertips rounded, without hooks; dactylus 4.44–5.45 (median 5.00, n = 5) times as long as wide, 1.25–1.36 (median 1.33, n = 5) times as long as palm, with tufts of setae distally; carpus slender, 6.36–8.17 (median 7.14, n = 5) times as long as wide, 1.04–1.40 (median 1.35, n = 5) times as long as merus. Merus not inflated, 5.83–7.83 (median 6.24, n = 5) times as long as wide, 1.06–1.17 (median1.13, n = 4) times as long as ischium. Third pereiopod ( Figure 4 D – G ) with dactylus ( Figure 4 E – G ) slightly sexually dimorphic, spiniform setae on flexor margin more curved, 3.78 times as long as wide (including terminal claw and spiniform setae on flexor margin) in males (n = 1), 4.00–5.00 (median 4.56, n = 4) times as long as wide in females, terminating in one claw, with 6–8 accessory spiniform setae on flexor margin, first spiniform seta on flexor margin strong and curved in some specimens; propodus not enlarged or curved distally, distal spiniform seta not enlarged, 10.6–14.29 (median 12.50, n = 5) times as long as wide, 3.24–3.73 (median 3.33, n = 5) times as long as dactylus; carpus 5.67–6.80 (median 5.86, n = 4) times as long as wide, 0.63–0.70 (median 0.66, n = 4) times as long as propodus, 0.50–0.59 (median 0.57, n = 4) times as long as merus, with one large spiniform seta near distal margin and 3–6 small spiniform setae proximally; merus 6.84–9.08 (median 8.47, n = 4) times as long as wide, 1.69–2.00 (median 1.74, n =4) times as long as carpus, with 3–5 strong movable spiniform setae on externo-inferior margin; ischium without or with one spiniform seta. Fourth pereiopod similar to third but slightly smaller. Fifth pereiopod ( Figure 4 H, I ) was slender; dactylus ( Figure 4 I ) 3.6–5.00 (n = 2) times as long as wide (including terminal claw and spiniform setae on flexor margin), terminating in one large claw, with 16–18 spiniform setae on flexor margin; propodus with small spiniform setae on ventral margin, distal pair of spiniform setae not enlarged, propodus 12.40–13.80 (median 12.50, n = 3) times as long as wide, 3.44–3.75 (n = 2) times as long as dactylus; carpus 5.83–7.09 (median 6.62, n = 3) times as long as wide, 0.56–0.57 (median 0.57, n = 3) times as long as propodus, 0.66–0.68 (median 0.67, n = 3) times as long as merus, with one strong spiniform seta near distal margin and five small spiniform setae proximally; merus 7.43–8.43 (median 8.40, n = 3) times as long as wide, 1.47–1.51 (median 1.49, n = 3) times as long as carpus, with 2–4 strong appressed movable spiniform setae on externo-inferior margin. Ischium with one or without spiniform seta.

Pleopods: Endopod of male first pleopod ( Figure 4 J ) elongated triangular, lacking appendix interna, 2.0 (n = 1) times as long as proximal width, 0.40 times as long as exopod, with long plumose setae on distal margin, and few shorter plumose setae on inner and outer margins. Male second pleopod with appendix masculina rod-shaped ( Figure 4 K ), 10.0 (n = 1) times as long as wide, 0.83 (n = 1) times as long as endopod, armed with strong spiniform setae on inner margin and distal margin; appendix interna originating from about 0.4 times the length of appendix masculina, reaching to about 0.65 times the length of appendix masculina.

Reproductive biology: Ovigerous females with medium-sized embryos; embryo size 0.66–0.76 × 0.39–0.49 mm (n = 6). Twenty-five and thirty embryos counted in two ovigerous females.

Size: Postorbital carapace length of apparently adult specimens 2.1–4.3 mm.

Colouration: Variable. Some specimens reddish with a pale median dorsal line extending from the rostrum to the sixth pleomere, some specimens mottled with reddish and creamy chromatophores, smaller specimens mostly transparent [ 4, 25].

Distribution: The species is known from rivers draining into the Timor Sea. From the Fitzroy River in Western Australia eastwards to the Howard River in the Northern Territory.

Etymology: The species name magnovis is derived from the rather large size of the embryos of the proposed new species compared to C. serratirostris .

Common name: North Australian Chameleon Shrimp.

Remarks: The general morphology of Caridina magnovis n. sp., with a straight rostrum, armed throughout close to the tip and a high number of postorbital teeth (5–8), a long stylocerite, slender chelipeds and distal margin of the telson armed with long plumose setae clearly exceeding a lateral pair of strong spiniform setae and the variable coloration of living specimens resembles that of Caridina serratirostris de Man, 1892 . The proposed new species differs from C. serratirostris in the armature of the rostrum, i.e., ventral teeth located in the distal half of the rostrum vs. ventral teeth placed at midlength of the rostrum in C. serratirostris . The stylocerite of Caridina magnovis n. sp. is shorter, reaching to 0.89–1.05 of the first segment of antennular peduncle vs. clearly exceeding this segment (1.09–1.47 times the length of the first segment). Carpus of first pereiopod is 2.12–3.22 times as long as wide in Caridina magnovis n. sp. vs. 2.63–4.67 times in C. serratirostris . Dactylus of third pereiopod with 6–8 spiniform setae vs. with 4–5 in C. serratirostris . Dactylus of fifth pereiopod with 16–18 spiniform setae on flexor margin, first seta not markedly enlarged vs. with 11–17 spiniform setae, first seta enlarged in C. serratirostris . Uropodal diaeresis with 12–15 movable spiniform setae vs. with 16–21 movable spiniform setae in C. serratirostris . Preanal carina rounded, without prominent tooth in most specimens (vs. preanal carina with a prominent hook-like tooth in all specimens of C. serratirostris ). Embryos 0.66–0.76 × 0.39–0.49 mm vs. 0.37–0.44 × 0.20–0.26 mm in C. serratirostris .

Figures

Figure 3. (A,C–F,I) Caridina magnovis n. sp. paratype ov. ♀cl 4.0 mm, NTM Cr019573; (B,G,H,J–O) Caridina magnovis n. sp. paratype ♂cl 2.7 mm, WAM C81394. (A,B) Carapace; (C) telson; (D) distal margin of telson; (E) preanal carina; (F) uropodal diaeresis; (G) antennular peduncle; (H) scaphocerite; (I,J) mandibles; (K) maxillulae; (L) maxillae; (M) first maxilliped; (N) palp of first maxilliped; (O) second maxilliped.

Figure 4. (A–E,G–K) Caridina magnovis n. sp. paratype ♂cl 2.7 mm, WAM C81394. (F) Caridina magnovis n. sp. paratype ov. ♀cl 4.0 mm, NTM Cr019573. (A) Third maxilliped, (B) first pereiopod, (C) second pereiopod, (D) third pereiopod, (E,F) dactylus of third pereiopod, (G) dactylus of fourth pereiopod, (H) fifth pereiopod, (I) dactylus of fifth pereiopod, (J) first pleopod, (K) second pleopod.