Caridina ponapensis, Mazancourt & Marquet & Keith, 2024

Caridina ponapensis sp. nov.

urn:lsid:zoobank.org:act:8165E679-E718-4975-8AF1-9784D16FC9F3

Figures 3C View Figure 3 , 5 View Figure 5 and 9C View Figure 9

- Caridina cf. weberi Pohnpei —de Mazancourt et al., 2019 [47]: 166, Figures 2–5 View Figure 2 View Figure 3 View Figure 4 View Figure 5 ;

- Non Caridina weberi parvirostris —Maciolek & Ford, 1987 [13]: 628;

- Non Caridina weberi —Maciolek & Ford, 1987 [13]: 628 (part?).—Nelson et al., 1996 [14]: 11 (part?).—Buden et al., 2001 [15]: 257 (part?).

Material examined

Type material

FEDERATED STATES OF MICRONESIA: Pohnpei Island . Holotype: MNHN-IU-2024-447 : 1 ♂ cl 2.4 mm, Nanpilriver ( station 2 ), 9 March 2012, 93 ma.s.l., 06 ◦ 54.498 ′ N, 158 ◦ 13.270 ′ E, coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois. GoogleMaps Paratypes: MNHN-IU-2024-448 : 1 ♀ ovig. cl 3.0 mm Nanpilriver ( station 1 ), 9 March 2012, 127 ma.s.l., 06 ◦ 55.242 ′ N, 158 ◦ 12.265 ′ E, coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois. GoogleMaps MNHN-IU-2024-449 : 1 ♂ cl 2.4 mm, Nanpilriver ( station 2 ), 9 March 2012, 93 ma.s.l., 06 ◦ 54.498 ′ N, 158 ◦ 13.270 ′ E, coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois. GoogleMaps MNHN-IU-2024-450 (DNA: CA1390 ): 1 ♀ cl 3.8 mm and MNHN-IU-2024-451 (DNA: CA1391 ): 1 ♀ ovig. cl 3.7 mm, Lehn Mesi river ( station 2 ), 06 ◦ 51.107 ′ N, 158 ◦ 11.396 ′ E, 10 March 2012, 139 ma.s.l., coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois. GoogleMaps MNHN-IU-2024-452 (DNA: CA1388 ): 1 ♀ ovig. cl 3.5 mm and MNHN-IU-2024-453 (DNA: CA1389 ): 1 ♀ ovig. cl 2.9 mm, Senipehn river ( station 2 ), 95 ma.s.l., 06 ◦ 51.906 ′ N, 158 ◦ 16.010 ′ E, 12 March 2012, coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois. GoogleMaps MNHN-IU-2024-454 : 1 ♀ ovig. cl 3.1 mm; Mahnd river , 06 ◦ 50.609 ′ N, 158 ◦ 17.212 ′ E, 14 March 2012, 107 m a.s.l., coll. M. Castelin, P. Keith, P. Gerbeaux, G. Marquet, and L. Taillebois GoogleMaps .

Comparative material

Caridina weberi De Man, 1892 : Syntypes MNHN-IU-2015-1755 2 ♂ cl 4.4–4.5 mm, 1 ♀ ovig. cl 6.1 mm.

Caridina parvirostris De Man, 1892 : Syntypes MNHN-IU-2015-1748 cl. 3.1–3.2 mm, 1 ♀ cl. 4.2 mm.

Caridina keiensis Roux, 1911 : Lectotype NMB 6.IV.b 1 ♀ ovig. cl 5.7 mm; Paralectoptypes NMB 6.IV.a 2 ♂ cl 2.6 mm; NMB 6.IV.b 1 ♀ cl 5.5 mm; one male cl 3.4 mm.

Description

Cephalothorax. Suborbital angle indistinguishably fused with antennal spine. Pterygostomian margin rounded. Rostrum ( Figure 5m,n View Figure 5 ): curved down, short, 0.2–0.3 of cl, not overreaching first segment of antennular peduncle, armed with four–six teeth on dorsal margin, zero of them situated on carapace behind orbital margin, ventral margin with zero–one teeth.

Eyes well-developed, anterior end reaching to 0.7 times length of basal segment of antennular peduncle. Antennular peduncle 0.57 times as long as carapace. Anterolateral angle reaching 0.28 times length of the second segment, second segment distinctly shorter than third segment. Stylocerite reaching to 0.9 times length of basal segment of antennular peduncle.

Pereiopods. Epipods on first four pereiopods. P1 ( Figure 5a View Figure 5 ): chela about 1.8–2.0 times as long as wide, movable finger 2.0–3.3 times as long as wide, 0.5–1.2 times length of palm; carpus 1.3–1.9 times as longas wide. P2 ( Figure 5b View Figure 5 ) more slender and longer than first pereiopod with chela 2.4–2.6 times as long as wide: movable finger 4.0–4.5 times as long as wide, 1.3–1.8 times length of palm; carpus slender 5.6–6.5 times as longas wide. P3 ( Figure 5c View Figure 5 ): stout, dactylus ( Figure 5e View Figure 5 ) 2.4–3.7 times as long as wide terminal spiniform (seta included) with five–six spines on flexor margin in addition to the terminal spine; propodus 7.9–8.9 times as long as wide, 3.5–4.8 times as long as dactylus. P5 ( Figure 5d View Figure 5 ): dactylus ( Figure 5f View Figure 5 ) 3.0–4.3 times as long as wide with 29–39 spiniform setae on flexor margin; propodus 10.6–15.7 times as long as wide, 4.1–5.2 times as long as dactylus.

Abdomen. Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite 0.48 times as long as carapace, 1.5 times as long as fifth somite, 0.86 times as long as telson.

Telson ( Figure 5i View Figure 5 ) two times as long as wide, with four pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with a median process, rounded with five–nine very long intermediate plumose setae longer than lateral ones.

Male Pl1 ( Figure 5k View Figure 5 ): Endopod subtriangular, 0.53 times length of exopod, appendix interna stout, exceeding end of endopod.

Male Pl2 ( Figure 5l View Figure 5 ): Long appendix masculina on second pleopod reaching 0.85 times length of endopod; appendix interna reaching about 0.64 times length of appendix masculina.

Preanal carina high ( Figure 5g View Figure 5 ) and unarmed.

Uropodal diaeresis ( Figure 5h View Figure 5 ) with 19–24 spinules.

Eggs sized: 0.43–0.50 mm × 0.25–0.29 mm ( Figure 5j View Figure 5 ).

Habitat

This new species is largely rheophile and prefers waters that are fresh and fast-flowing from the lower to the higher courses.

Etymology

C. ponapensis sp. nov. is named after the former name of Pohnpei, Ponape, from where this new species is endemic.

Colour pattern ( Figure 9C View Figure 9 )

Body transparent with spots of chromatophores scattered over the body.

Distribution

This new species seems endemic to Pohnpei Island.

Remarks

Based on the form of the rostrum, the high pre-anal carina, the large number of uropodal teeth, and the shape of the telson, this new species belongs to the C. weberi species group. In this group, it is most similar to C. parvirostris by its short curved-down rostrum and slender P2 carpus: 5.6–6.5 (vs. 6.0–7.4). However, it could be easily separated from C. parvirostris by lower numbers of dorsal and ventral teeth on the rostrum, respectively, 4–6 (vs. 8–10) and 0–1 (vs. 2). This new species is also similar to C. keiensis by its rostrum (lower numbers of dorsal and ventral teeth on the rostrum, respectively, 4–6 (vs. 2–13) and 0–1 (vs. 1–2)) and its relatively long stylocerite reaching to 0.90 times the length of the basal segment of antennular peduncle (vs. 0.92), but it could be easily distinguished by its longer P2 carpus 5.6–6.5 (vs. 3.5–4.5), and the size of the eggs 0.43–0.50 mm × 0.25–0.29 mm (vs. 0.39–0.42 mm × 0.24–0.25 mm).