Caridina henriettae, Mazancourt & Mennesson & Marquet & Keith, 2025

Mazancourt, Valentin De, Mennesson, Marion, Marquet, Gérard & Keith, Philippe, 2025, Revision of the species of Caridina (Decapoda: Atyidae) from the Western Indian Ocean islands with description of a new species, European Journal of Taxonomy 1007, pp. 57-86 : 68-74

Caridina henriettae sp. nov.

urn:lsid:zoobank.org:act:F229A5EF-5D4B-412D-B6F8-285C1B0B1C27

Figs 2F , 3‒4 , 5D, G–H

Caridina serratirostris – Holthuis 1965: 25, fig. 8. — Costa 1980: 691. — Gurney 1984: 568 (key). – Keith et al. 1999: 44; 2006: 56. — Keith 2002: 100. — Richard & Clark 2010: 310 (part), figs 3, 4a–n, p–q. — Bouchard et al. 2013: 9. — Emmerson 2016: 170. — Hoarau 2018: 1.

Caridina wyckii – Weber 1897: 168 (part).

Diagnosis

Typical morphology of the C. serratirostris species group: rostrum armed with many dorsal teeth, at least 6 of them on the carapace, a usually long stylocerite and a rounded endopod of the first male pleopod,

without appendix interna. Well-developed arthrobranch at the base of P1. Telson with a pair of plain long lateral spines and 1 pair of shorter, plain lateral spines. P3 propodus 11.2‒12.8 as long as wide.

Etymology

The new species is dedicated to our friend Elvina Henriette , Research Scientist and Director of the NGO “Gaea Conservation Network Seychelles ”, in recognition of her work and passion for the freshwater fauna of Seychelles islands.

Type material

Holotype

MAURITIUS • ♂ (cl 2.9 mm); Rivière des Anguilles ; 20°28.802′ S, 57°33.378′ E; 13 Nov. 2002; P. Keith, G. Marquet and ARDA leg.; DNA voucher: CA2304 ; MNHN-IU-2015-1914; MNHN.

Paratypes

MAURITIUS • 1 ♀ (cl 4.1 mm); same data as for for holotype; DNA voucher: CA2305 ; MNHN-2025- 140; MNHN .

MADAGASCAR • 1 ♀ ovig. (cl 4.9 mm); Fanambana River (Station 37); 14°33.193′ S, 50°10.393′ E; 11 m a.s.l.; 7 Jul. 2008; DIAMSOI leg.; DNA voucher: CA1178 ; MNHN-2025-141; MNHN • 1 ♂ (cl 3.2 mm); same collection data as for preceding; DNA voucher: CA1431 ; MNHN-2025-142; MNHN .

MAURITIUS • 1 ♀ ovig. (cl 4.8 mm); Rivière de la Chaux; 20°24.350′ S, 57°42.269′ E; 12 Nov. 2002; ARDA leg.; DNA voucher: CA2042 ; MNHN-IU-2015-1933; MNHN • 1 ♂ (cl 3.0 mm); Beau Vallon; 1913; P. Carié leg.; MNHN-IU-2015-1909; MNHN .

LA RÉUNION • 1 ♀ ovig. (cl 4.4 mm); Rivière des Embouchures ; 21°2.093′ S, 55°42.899′ E; 13 Oct. 2015; P. Valade leg.; DNA voucher: CA2417 ; MNHN-2025-143; MNHN • 1 ♀ ovig. (cl 3.8 mm); same data as for preceding; DNA voucher: CA2418 ; MNHN-2025-144; MNHN • 1 ♀ ovig. (cl 3.6 mm); Rivière des Marsouins ; 2 May 2022; Ocea Consult leg.; DNA voucher: CA2949 ; MNHN-2025-145; MNHN • 1 ♀ ovig. (cl 3.6 mm); Rivière des Marsouins ; 21°1.970′ S, 55°42.949′ E; 8 Apr. 2024; P. Valade leg.; DNA voucher: CA3038 ; MNHN-2025-146; MNHN • 1 juv. (cl 2.4 mm); Rivière des Marsouins ; 21°1.970′ S, 55°42.949′ E; 6 Aug. 2023; P. Valade leg.; DNA voucher: CA3061 ; MNHN-2025-147; MNHN • 1 juv. (cl 2.3 mm); Rivière des Roches ; 21°0.398′ S, 55°41.661′ E; 13 Nov. 2023; P. Valade leg.; DNA voucher: CA3065 ; MNHN-2025-148; MNHN .

SEYCHELLES ‒ Mahé • 2 ♀♀ ovig. (cl 4.1‒4.7 mm), 1 ♀ (cl 4.0 mm); Bel Ombre; 4°36.966′ S, 55°25.063′ E; 2 Feb. 2020; P. Keith and M. Mennesson leg.; MNHN-2025-149; MNHN • 1 ♀ ovig. (cl 2.7 mm); Grand Anse; 4°40.502′ S, 55°26.728′ E; 20 Feb. 2020; P. Keith and M. Mennesson leg.; MNHN-2025-150; MNHN • 1 ♀ ovig. (cl 2.7 mm); same data as for preceding; DNA voucher: CA3000 ; MNHN-2025-151; MNHN . ‒ Praslin • 1 ♀ ovig. (cl 4.1 mm); 10 Oct. 2003; no locality data; ARDA leg.; DNA voucher: CA2026 ; MNHN-IU-2015-1932; MNHN • 1 ♀ ovig. (cl 3.4 mm); Nouvelle Découverte ; 4°20.179′ S, 55°43.349′ E; 19 Feb. 2024; P. Keith and M. Mennesson leg.; MNHN-2025-152; MNHN • 2 ♀♀ ovig. (cl 3.2‒3.6 mm); Nouvelle Découverte ; 4°20.179′ S, 55°43.349′ E; 21 Feb. 2020; P. Keith and M. Mennesson leg.; MNHN-2025-153; MNHN • 1 ♀ ovig. (cl 3.6 mm); same data as for preceding; DNA voucher: CA2998 ; MNHN-2025-154; MNHN • 1 ♀ ovig. (cl 3.4 mm); same data as for preceding; DNA voucher: CA2999 ; MNHN-2025-155; MNHN . ‒ Silhouette • 1 ♀ (cl 3.4 mm); Anse Mandon ; 4°28.014′ S, 53°13.500′ E; 28 Nov. 2012; P. Keith leg.; DNA voucher: CA1491 ; MNHN-2025-156; MNHN • 1 ♀ ovig. (cl. 4.5 mm); same data as for preceding; DNA voucher: CA1492 ; MNHN-2025-157; MNHN • 4 ♀♀ ovig. (cl 3.3‒3.7 mm), 1 ♀ (cl 3.3 mm); St Gore River ; 4°30.115′ S, 55°13.521′ E; 18 Feb. 2020; P. Keith and M. Mennesson leg.; MNHN-2025-158; MNHN .

Description

CEPHALOTHORAX. Antennal spine ventral to inferior orbital angle. Pterygostomian margin rounded. Rostrum ( Fig. 3M–O ): straight, short, 0.6–0.7 of cl, reaching beyond end of antennular peduncle, armed with 19–31 teeth on dorsal margin, 6–10 of them situated on carapace behind orbital margin, ventral margin with 5–7 teeth. Eyes developed, anterior end reaching to 0.59 × length of basal segment of antennular peduncle. Long antennular peduncle, 0.67 (♀) – 0.78 (♂) × as long as carapace; second segment distinctly longer than third segment. Stylocerite reaching to middle of second segment of antennular peduncle.

PEREIOPODS. Epipods on first four pereiopods. P1 ( Fig. 3A ): chela about 2.4–3.3 × as long as wide, movable finger 3.7‒5.8 as long as wide, 1.4–1.9 × length of palm; carpus 3.6–4.6 × as long as wide, well developed arthrobranch ( Fig. 4 ). P2 ( Fig. 3B ) more slender and longer than first pereiopod, with chela 3.7–5.2 × as long as wide: movable finger 5.2‒11.0 × as long as wide, 1.4–2.4 × as long as palm; carpus slender, 7.7‒9.6 × as long as wide. P3 ( Fig. 3C ): slender, dactylus ( Fig. 3E ) 3.2–4.0 × as long as wide (terminal spiniform seta included), with 5–8 spiniform setae on flexor margin including terminal one; propodus 11.2‒12.8 × as long as wide, 3.2‒4.4 × as long as dactylus. P5 ( Fig. 3D ): dactylus ( Fig. 3F ) 3.9‒4.4 as long as wide, with 7‒13 spiniform setae on flexor margin; propodus 15.8‒23.9 × as long as wide, 4.4–50 × as long as dactylus.

ABDOMEN. Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite 0.49 × as long as carapace, 1.3 × as long as fifth somite, shorter than telson.

TELSON ( Fig. 3H ). 3.0 × as long as wide, with 6 pairs dorsal spines including subterminal spines, 1 pair of plain long lateral spines, 1 pair of shorter plain lateral spines and 6‒11 long, stalked, plumose processes present at rounded posterior margin.

MALE PLEOPODS. Pl1 ( Fig. 3J ): endopod rounded, 2.0 × as long as wide, reaching 0.35 × as long as endopod, no appendix. Pl2 ( Fig. 3K ): appendix masculina reaching 0.74 × as long as endopod; appendix interna reaching 0.82 × as long as appendix masculina.

PRE-ANAL CARINA ( Fig. 3I ). High, with a spine.

UROPODAL DIAERESIS ( Fig. 3G ). With 13–15 spinules.

EGGS. Ovigerous females with small eggs ( Fig. 3L ), size: 0.37–0.46 × 0.24–0.27 mm.

Distribution

South Africa, Mozambique, Madagascar, Seychelles, Comoros, La Réunion, Mauritius.

Habitat

Fresh or brackish water in the lower course and estuary of rivers.

Remarks

This new species belongs to the Caridina serratirostris species group based on the presence of a rostrum armed with many dorsal teeth, at least 6 of them on the carapace, with a usually long stylocerite and with a rounded endopod of the first male pleopod, without appendix interna. But it is easy to distinguish this new species from type specimens of congeners by its telson with a pair of plain long lateral spines and 1 pair of shorter, plain lateral spines (vs only a pair of plain lateral spines) and by its P3 propodus shorter 11.2‒12.8 × as long as wide (vs 14.2‒17.1). Among this group, our new species is closer to C. serratirostris than C. celebensis due to the presence of a well-developed arthrobranch at the base of the P1 (vs reduced or absent, see Cai & Shokita 2006b)

Richard & Clark (2010) reported this species under the name C. serratirostris from Mozambique and South Africa noting the presence of shorter inner lateral spines on the telson which the syntypes of C. serratirostris do not possess. Recent sampling trips to the localities where the species was collected in South Africa – the iLovu or the Umbilo rivers near Durban ‒ by two of the authors (VM and GM) failed to retrieve this species, suggesting either that this area is the southern limit of its range and its presence may be occasional, or that the species does not occur there anymore due to the heavy urbanization around these rivers (pers. obs.).

Identification key for the species of Caridina H. Milne Edwards, 1837 from the South-Western Indian Ocean

1. Stylocerite reaching distinctly beyond the base of the second segment of the antennular peduncle ............................................................................................................ C. henriettae sp. nov.

– Stylocerite at most attaining the end of the first segment of the antennular peduncle ..................... 2

2. Rostrum rather constantly long, reaching well beyond scaphocerite .... C. natalensis De Man, 1908 – Rostrum short or reaching at most to or slightly beyond the end of the antennular peduncle ......... 3

3. Uropodal diaeresis with 16‒23 spinules ........................................................................................... 4 – Uropodal diaeresis with 8‒15 spinules ............................................................................................. 5

4. Dactylus of P5 with 26‒37 spiniform setae; ovigerous female with few and large eggs ................... .................................................................................................. C. similis Bouvier, 1904 ( Seychelles)

– Dactylus of P5 with 33‒81 spiniform setae; ovigerous female with numerous and small eggs ......... ........................................................................................................ C. typus H. Milne Edwards, 1837

5. Dorsal margin of telson unarmed; dactylus of P5 with 28‒30 spiniform setae .................................. ................................................................................................. C. mauritii Bouvier, 1912 ( Mauritius)

– Dorsal margin of telson armed; dactylus of P5 with 31‒60 spiniform setae ...................................... ..................................................................................... C. spathulirostris Richters, 1880 ( Mauritius)

Figures

Fig. 2. Bayesian inference phylogenetic tree obtained from the 16S marker. Numbers above branches represent Bayesian posterior probabilities, numbers under branches are Maximum Likelihood bootstraps. Letters indicate clades recognized as valid species and colored boxes are species complexes.

Fig. 3. Caridina henriettae sp. nov. A–F, H, O. ♂, holotype (MNHN-IU-2015-1914). G, J–K. ♂, paratype (MNHN-IU-2015-1909). I, L. Ovigerous, ♀, paratype (MNHN-IU-2015-1933). M. Ovigerous female, paratype (MNHN-IU-2025-143). N. Ovigerous female, paratype (MNHN-IU-2025-152). A. First pereiopod. B. Second pereiopod. C. Third pereiopod. D. Fifth pereiopod. E. Dactylus of third pereiopod. F. Dactylus of fifth pereiopod. G. Uropodal diaeresis. H. Telson. I. pre-anal carina. J. First male pleopod. K. Second male pleopod. L. Undeveloped eggs. M–N. Rostrum variation. O. Cephalothorax.

Fig. 4. Dissected branchial chamber of a specimen of Caridina henriettae sp. nov., paratype (MNHN- 2025-149) showing the developed arthrobranch at the base of the first pereiopod (black arrow).

Fig. 5. Live coloration of the species of Atyidae from the South West Indian Ocean. A. Atyoida serrata Bate, 1888 from La Réunion (credit E. Vigneux). B. Caridina natalensis De Man, 1908 from the Seychelles (credit P. Keith). C. Caridina spathulirostris Richters, 1880 from Mauritius (credit Hoareau). D. Caridina henriettae sp. nov. from the Seychelles (credit P. Keith). E. Caridina similis Bouvier, 1904 from the Seychelles (credit Y. Zitte). F. C. typus H. Milne Edwards, 1837 from La Réunion (credit E. Vigneux). G–H. C. henriettae sp. nov. from La Réunion (credit E. Vigneux).