Caridina occidentalis, Mazancourt & Bréthiot & Marquet & Keith, 2022

Mazancourt, Valentin de, Bréthiot, Julien, Marquet, Gérard & Keith, Philippe, 2022, West Side Story: A molecular and morphological study of Caridina longicarpus Roux, 1926 (Decapoda, Caridea, Atyidae) from New Caledonia reveals a new species, Zoosystema 44 (18), pp. 463-474 : 469-472

Caridina occidentalis n. sp.

( Figs 4 ; 5 )

urn:lsid:zoobank.org:act:2B9014C4-ACBB-44A4-B5BC-A4D3475D2493

Not Caridina weberi – Choy & Marquet 2002: 220.

Not Caridina weberi – Marquet et al. 2003: 72-73.

Not Caridina weberi longicarpus (sp. Ncal A / NCal 1) – Page et al. 2007: 649 (GenBank: DQ478535 and DQ478536 ). — de Mazancourt et al. 2017: fig. 4.

Not Caridina longicarpus – de Mazancourt et al. 2019a: 166 (part: CA1611), figs 2-5.

MATERIAL EXAMINED. — Holotype. New Caledonia • 1♂ cl 4.0 mm; Pouéo river ; 21°26.326’S, 165°31.909’E; 180 m a.s.l.; 28.IX.2016; V. de Mazancourt, P.Tiberghien & G. Marquet leg.; DNA: CA1657; MNHN-IU-2018-3309 .

Paratypes. New Caledonia • 1♀ cl 7.0 mm; same collection data as for holotype; DNA: CA1611 ; MNHN-IU-2018-3311 • 1♀ cl 7.7 mm; Pouéo river ( HYNC797 ); 12.XI.2017; 21°29.931’S, 165°30.701’E; 25 m a.s.l.; V. de Mazancourt & N. Charpin leg.; DNA: CA1656 ; MNHN-IU-2018-3310 • 1♂ cl 4.4 mm; same collection data as preceding; DNA: CA1658 ; MNHN-IU-2018-3312 • 1♀ cl 5.3 mm; same collection data as preceding; DNA: CA2050 ; MNHN-IU-2018-3318 • 1♀ cl 5.7 mm; Voh river ; 20°54.884’S, 164°46.275’E; 38 m a.s.l.; VI.2016; N. Charpin leg.; DNA: CA1886 ; MNHN-IU-2018-3316 • 1♀ cl 5.0 mm; same collection data as preceding; DNA: CA1884 ; MNHN-IU-2018-3314 • 1♀ ovig. cl 5.9 mm; same collection data as preceding; DNA: CA1883 ; MNHN- IU-2018-3313 • 1♀ ovig. cl 5.4 mm; same collection data as preceding; DNA: CA1883 ; DNA: CA1885 ; MNHN-IU-2018-3315 • 1♀ cl 6.0 mm; Ouaméni river ( HYNC778 ); 21°49.546’S, 165°56.714’E; 37 m a.s.l.; 5.XI.2017; V. de Mazancourt & N. Charpin leg.; DNA: CA2049 ; MNHN-IU-2018-3317 • 1♀ cl 5.0 mm; Nekouri river ( HYNC1892 ); 21°34.805’S, 165°36.568’E; 44 m a.s.l.; 15.XI.2017; V. de Mazancourt & N. Charpin leg.; DNA: CA2053 ; MNHN- IU-2018-3321 • 1♀ cl 5.7 mm; same collection data as preceding; DNA: CA2052 ; MNHN-IU-2018-3320 • 1♀ ovig. cl 6.3 mm; same collection data as preceding; DNA: CA2051 ; MNHN-IU-2018-3319 • 1♂ cl 4.0 mm; Farino river ; 21°39.717’S, 165°46.344’E; 250 m a.s.l.; 9.XI.2012; N. Mary leg.; MNHN-IU-2018-3384 • 1♀ cl 6.5 mm; same collection data as preceding; MNHN-IU-2018-3385 • 1♀ cl 6.8 mm; same collection data as preceding; MNHN-IU-2018-3386. COMPARATIVE MATERIAL. — Caridina weberi De Man, 1892 : Syntypes: Indonesia • 1♂ cl 4.5 mm, 1♀ ovig. cl 6.1 mm, 1♂ cl 4.4 mm; Kotting , Flores Island; XII.1888; M. Weber leg.; MNHN- IU-2015-1755.

Caridina parvirostris De Man, 1892 : Syntypes: Indonesia • 2♂ cl 3.1-3.2 mm, 1♀ cl 4.2 mm; river near Bombang , Flores Island; I.1889; M. Weber leg.; MNHN-IU-2015-1748.

HABITAT. — This new species is largely rheophile and prefers fresh and well-oxygenated waters from the lower to higher courses (25- 250 m) ( Fig. 5C ).

ETYMOLOGY. — The name of this new species refers to its geographical distribution, restricted to the west coast of New Caledonia.

COLOUR PATTERN. — Similar to C. longicarpus : variable, body dark brown or blue with sometimes a white dorsal line stretching from the rostrum to the telson and numerous reddish-brown spots all over the body ( Fig. 5A, B ).

DISTRIBUTION. — Like the previous species, this species has been collected only in New Caledonia so far and also seems endemic. It is only found in rivers flowing to the west coast ( Fig. 6 ).

DESCRIPTION

Cephalothorax

Suborbital angle indistinguishably fused with antennal spine. Pterygostomian margin rounded. Rostrum ( Fig. 4M ): bent, short, 0.4-0.6 of cl (mean 0.5, n = 16), reaching from the base to slightly beyond the middle of second segment of antennular peduncle, armed with 15-22 teeth on dorsal margin (mean 17, n = 16), 0-3 of them situated on carapace behind orbital margin (mean 2, n = 16), ventral margin with 2-7 teeth (mean 4, n = 16).

Cephalic appendages

Eyes well developed, anterior end reaching to 0.47 length of basal segment of antennular peduncle. Antennular peduncle 0.50(♀)-0.57 (♂) times as long as carapace. Anterolateral angle reaching 0.30 length of the second segment, second segment same length as the third. Stylocerite reaching just before the top of the basal segment of antennular peduncle.

Pereiopods

Epipods on first four pereiopods. P1 ( Fig. 4A ): chela about 2.1-2.5 times as long as wide, movable finger 2.5-4.3 times as long as wide, 0.9-1.4 times length of palm; carpus 1.8- 2.5 times as long as wide. P2 ( Fig. 4B ): more slender and longer than P1 with chela 2.8-3.5 times as long as wide; movable finger 3.7-5.1 times as long as wide, 1.2-1.7 times length of palm; carpus slender 5.9-6.9 times as long as wide. P3 ( Fig. 4C ): stout, dactylus ( Fig. 4E ) 2.5-3.5 times as long as wide (terminal spiniform seta included) with 5-8 spiniform setae on flexor margin in addition to the terminal spiniform seta; propodus 7.3-10.3 times as long as wide, 3.7-5.8 times as long as dactylus. P5 ( Fig. 4D ): dactylus ( Fig. 4F ) 3.6-5.0 as long as wide with 55-90 spiniform setae on flexor margin (mean 68, n = 14); propodus 11.3-16.9 times as long as wide, 3.4-5.1 times as long as dactylus (mean 4.1, n = 14).

Abdomen

Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite about half of carapace length, 1.4 times as long as fifth somite, reaching 0.8 times length of telson.

Telson ( Fig. 4G )

2.4 times as long as wide, with 4-6 pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with a median process. Rounded with 7-15 (mean 11, n = 15) very long intermediate plumose setae, longer than lateral ones.

Pl1 ( Fig. 4J )

Endopod of male subrectangular, 2.7 times as long as wide, reaching 0.40 times of exopod, with an appendix on the subdistal outer margin which reaches beyond distal end of endopod on a short length.

Pl2 ( Fig. 4K )

Appendix masculina on second pleopod reaching 0.55 times length of endopod; appendix interna reaching 0.56 of appendix masculina.

Preanal carina ( Fig. 4I )

High, unarmed.

Uropodal diaeresis ( Fig. 4H )

With 17-24 spinules.

Eggs ( Fig. 4L )

0.46-0.49 × 0.27-0.39 mm.

REMARKS

C. occidentalis n. sp. looks like C. parvirostris De Man, 1892 by its downward bent rostrum and its long P2 carpus 5.9-6.9 times as long as wide (vs 6.0- 7.4 in C. parvirostris ) but the rostrum has more teeth 15-22 (vs 8-10 C. parvirostris ). This new species can be separated from C. weberi De Man, 1892 by its rostrum with more teeth 15-22 (vs 11-15 C. parvirostris ) and a longer P2 carpus 5.9-6.9 times as long as wide (vs 4.9-5.4 C. parvirostris ).

C. occidentalis n. sp. occurring in west coast rivers differs from C. longicarpus Roux, 1926 , occurring in rivers of the East coast:

– by its rostrum: 0.4-0.6 of cl, mean 0.5 (vs 0.2-0.6, mean 0.39), armed with 15-22 teeth on dorsal margin (mean 17), (vs 10-24 in C. longicarpus , mean 16), 0-3 of them situated on carapace behind orbital margin (mean 2) (vs 0-2 of them situated on carapace behind orbital margin, mean 0);

– by its P5 dactylus with 55-90 spiniform setae, 63-90, mean 68 on flexor margin (vs 27-72, 27-59, mean 52) and its propodus 3.4-5.1 times as long as dactylus, mean 4.1 (vs 4.1-5.4, mean 4.5);

– by its telson with 7-15 (mean 11) very long intermediate setae longer than lateral ones (vs with 5-10 in C. longicarpus , (mean 7) very long intermediate setae longer than lateral ones).

Figures

FIG. 4. — Caridina occidentalis n. sp.: A-G, I, L, M, MNHN-IU-2018-3311: first pereiopod (A), second pereiopod (B), third pereiopod (C), fifth pereiopod (D), dactylus of third pereiopod (E), dactylus of fifth pereiopod (F), telson (G); pre-anal carina (I), eggs (L); cephalothorax (M); H, MNHN-IU-2018-3312: uropodal diaeresis; J, K, holotype MNHN-IU-2018-3309: male first pleopod (J), male second pleopod (K). Scale bars: A-D, G, J-L, 0.5 mm; E, F, 0.1 mm; M, 1 mm.

FIG. 5. — A, B, Caridina occidentalis n. sp.: live coloration, female in right lateral view (A); live coloration, female, left lateral view of the rostrum (B); C, typical habitat, Nékouri river, Bourail, New Caledonia. Photographs: A, C, V. de Mazancourt; B, N. Charpin.

FIG. 6. — Distribution of Caridina longicarpus Roux, 1926 and Caridina occidentalis n. sp. in New Caledonia with the sampling localities of the present study.Grey arrows indicate the main oceanic currents:North Caledonian Jet (NCJ); South Equatorial Current (SEC); SubTropical CounterCurrent (STCC); Vauban Current (VC); Alis Current of New Caledonia (ACNC); arrow widths indicate the strengths of the currents (from Cravatte et al. 2015); blue area and dashed line represent the barrier reef and its lagoon;black line separates watersheds draining the East coast to those draining the West coast; star indicates Oubatche, the locality where the lectotype of Caridina longicarpus was collected.