Caridina choiseul Mazancourt & Boseto & Marquet & Keith 2020, sp. nov.

Caridina choiseul sp. nov.

urn:lsid:zoobank.org:act: 4C3B5DD9-C268-4876-AE84-5FF7CDD01DAE

Figs 2J, 6, 25E

Caridina sp. 2 Solomon – de Mazancourt et al. 2019a: 166, 169–170.

Etymology

Named after the island of Choiseul, where this new species occurs. The name is used as a noun in apposition.

Material examined

Holotype

SOLOMON ISLANDS • ♂, cl 3.9 mm; Choiseul Island, Creek 2; 06°59.027´S, 156°47.913´E; 93 m a.s.l.; 14 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20821.

Paratypes

SOLOMON ISLANDS – Choiseul Island • 1 ♀, cl 4.5 mm; same collection data as for holotype; MNHN-IU-2014-20822 • 1 ♂, cl 3.8 mm; Lopakare River; 07°01.613´S, 156°46.567´E; 20 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20823 • 1 ♂, cl 4.0 mm; same collection data as for preceding; MNHN-IU-2014-20824 • 1 ♀ ovig., cl 4.5 mm; same collection data as for preceding; MNHN-IU-2014-20825 • 1 ♀ ovig., cl 4.7 mm; same collection data as for preceding; MNHN-IU-2014-20826 • 1 ♀, cl 4.6 mm; same collection data as for preceding; DNA voucher: CA1277; MNHN-IU-2014-20827 • 1 ♀, cl 4.8 mm; same collection data as for preceding; MNHN- IU-2014-20828 • 1 ♂, cl 4.0 mm; Pisuku River, sector 1; 06°58.951´S, 156°46.582´E; 15 m a.s.l.; 10 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20829 • 1 ♂, cl 4.1 mm; same collection data as for preceding; DNA voucher: CA1285; MNHN-IU-2014-20830 • 1 ♀, cl 4.7 mm; same collection data as for preceding; MNHN-IU-2014-20831 • 1 ♀ ovig., cl 5.1 mm; same collection data as for preceding; MNHN-IU-2014-20832 • 1 ♀ ovig., cl 5.5 mm; same collection data as for preceding; MNHN-IU-2014-20833 • 1 ♂, cl 4.2 mm; Pisuku River, sector 2; 06°58.900´S, 156°46.685´E; 66 m a.s.l.; 10 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20834 • 1 ♀, cl 5.4 mm; same collection data as for preceding; MNHN-IU-2014-20835 • 1 ♂, 4.2 mm; Pisuku River, upstream; 06°58.965´S, 156°46.718´E; 12 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN- IU-2014-20836 • 1 ♀, cl 4.5 mm; same collection data as for preceding; MNHN-IU-2014-20837 • 1 ♀, cl 4.1 mm; same collection data as for preceding; MNHN-IU-2014-20838 • 1 ♀, cl 5.1 mm; same collection data as for preceding; MNHN-IU-2014-20839.

Comparative material

Caridina variabilirostris (de Mazancourt, Marquet & Keith, 2018)

See de Mazancourt et al. (2018a)

Caridina brachydactyla (De Man, 1908)

INDONESIA • lectotype (designated by Richard & Clark 2010), ♀ ovig., cl 4.8 mm; Flores Island, river near Reo; Nov. 1888; M. Weber leg.; RMNH Crust D. 977 • 2 paralectotypes, ♀♀ ovig., cl 5.3–5.4 mm; Flores Island, river in Mbawa; Jan. 1889; M. Weber leg.; RMNH 2552 • 1 ♀, cl 5.8 mm; Bali Island; NMB 1054 a • 2 ♂♂, cl 2.7–3.7 mm, 1 ♀ ovig., cl 4.3 mm, 1 ♀, cl 4.8 mm; Sulawesi, Palopo, Macaui (locality code: 63.10); W. Klotz leg.; ZMB • 1 ♀ ovig., cl 4.0 mm; Sulawesi, Palopo, Tojo (locality code: 64.10); W. Klotz leg.; ZMB.

Caridina elongapoda (Liang & Yan, 1977)

CHINA • 3 ♂♂, cl 2.8–3.5 mm, 1 ♀, cl 4.2 mm; Hong Kong, Pak Tam Chung and Kai Sai Chau (locality codes 14.11 and 22.09); W. Klotz leg.; ZMB.

MALAYSIA • 1 ♂, cl 4.2 mm, 1 ♀, cl 4.3 mm, 1 ♀ ovig., cl 4.3 mm; Pulau Tioman, Sungai Asah; 24 Jun. 1997; Ng et al. leg.; ZRC 1998.0865.

Caridina peninsularis (Kemp, 1918)

MALAYSIA • lectotype (designated by Cai et al. 2007), ♂, cl 3.2 mm; Penang Island, Botanical Garden; Feb. 1916; N.Anandale leg.; MNHN-IU-2015-1749 • 1 paralectotype, ♀ ovig., cl 5.4 mm; same collection data as for lectotype; MNHN-IU-2015-1750 • 1 paralectotype, ♀, cl 3.4 mm, 1 paralectotype, ♀ ovig., cl 5.2 mm, 1 paralectotype, ♂, cl 3.9 mm; same collection data as for lectotype; NHM 1919.11.1.12-21 (1761124).

SINGAPORE • 1 ♀ ovig., cl 5.1 mm, 1 ♂, cl 4.2 mm; Tanglin [incorrectly spelt Tangtum in NHM register and on label, see Richard & Clark 2014]; 1958; Bedford and Lanchester leg.; NHM 1958.8.7.14–17 (1749569).

Caridina variabilis (de Mazancourt, Rogers & Keith, 2018)

See de Mazancourt et al. (2018b).

Caridina sundanella (Holthuis, 1978)

INDONESIA • 1 syntype ♂, cl 3.6 mm, 1 syntype, ♀, cl 5.2 mm; Sumba Island, West Sumba, 4 km N of Waimangura, Waikamburu Brook, Station 450; 250 m a.s.l.; 19 Aug. 1949; E. Sutter and A. B̹hler leg.; NMB 989 a.

Description

CEPHALOTHORAX. Carapace (Fig. 6m) smooth, glabrous, with sharp antennal spine placed at lower orbital angle. Pterygostomial margin subrectangular. Variable length rostrum, 0.5–1.2 of cl, 16–28 dorsal teeth closely set, leaving 0.0–0.35 unarmed distally, 1–4 post-orbital teeth present. 7–12 teeth present on ventral margin extending from proximal end either to tip or with short distal part unarmed. Number of dorsal teeth on rostrum before first ventral tooth 13–19. Eyes well developed, anterior end reaching to 0.72 times length of basal segment of antennular peduncle. Antennular peduncle 0.75 (♀) – 0.88 (♂) times as long as carapace. Anterolateral angle reaching 0.30 length of second segment, second segment distinctly longer than third segment. Stylocerite reaching to 0.83 length of basal segment of antennular peduncle.

PEREIOPODS. Slender P1 (Fig. 6a): chela about 1.8–2.3 times as long as wide, dactylus 3.3–4.8 times as long as wide, 1.3–1.8 length of palm; carpus 1.9–2.4 times as long as wide with shallow excavation on anterior margin. P2 (Fig. 6b) more slender and longer than first pereiopod: chela 2.0–27 times as long as wide, dactylus 3.8–6.3 times as long as wide, 1.3–1.8 times length of palm; carpus 4.6–7.7 times as long as wide. P3 (Fig. 6c): dactylus (Fig. 6e) 2.7–3.8 times as long as wide (terminal spiniform setae included) with 5–6 spiniform setae on flexor margin in addition to terminal one; propodus 13.0–19.6 times as long as wide, 5.0–6.8 times as long as dactylus. P5 (Fig. 6d): dactylus (Fig. 6f) 3.3–4.9 times as long as wide, with 28–41 spiniform setae on flexor margin; propodus 13.6–25.5 times as long as wide, 4.8–6.5 times as long as dactylus.

ABDOMEN. A typical dorsal hump over third abdominal somite. Sixth abdominal somite 0.7 as long as carapace, 1.9 times as long as fifth somite, slightly shorter than telson.

TELSON (Fig. 6i). 2.9–3.2 times as long as wide, with four pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with a median process, distal setae short, lateral pair slightly longer than intermediate setae (4–7).

MALE PLEOPODS. Pl1 (Fig. 6j): endopod subtriangular, 2.1 times as long as wide, 0.15 times as long as exopod, with an appendix interna placed at distal end. Pl2 (Fig. 6k): appendix masculina reaching 0.56 times length of endopod; appendix interna reaching 0.70 of appendix masculina.

PRE- ANAL CARINA (Fig. 6g). With a spine or not.

UROPODAL DIAERESIS (Fig. 6h). With 9–14 spinules.

EGGS (Fig. 6l). Size: 0.40–0.45 × 0.24–0.28 mm.

Habitat

This species prefers fresh and well-oxygenated waters. It is found from the lower to the higher course. It is more abundant in the areas situated above waterfalls, where predators are less numerous.

Colour pattern (Fig. 25E)

The colour of the body is hyaline with many red dots.

Distribution

As far as we know, this species is known only from Choiseul Island.

Remarks

In this new species, rostrum length is variable (cl 0.5–1.2), being longer in the lower course and shorter in the upper course, as recently found by de Mazancourt et al. (2017b) who highlighted the “Pinocchioshrimp effect” on C. variabilirostris de Mazancourt, Marquet & Keith, 2018 from Pohnpei. When the rostrum is short, the general appearance resembles that of C. mertoni Roux, 1911, whereas when the rostrum is long, the general appearance is similar to that of C. brachydactyla De Man, 1908. Similarly, C. variabilis de Mazancourt, Rogers & Keith, 2018 from Guam and Palau shows a longer or a shorter rostrum depending on the altitude.

Caridina choiseul sp. nov. looks like C. variabilis and C. variabilirostris from Micronesia by the number of teeth and their placement on the rostrum, the proportions between the joints of pereiopods and egg size. However, it can be differentiated by the pre-anal carina that sometimes has a spine (vs always unarmed in C. variabilis and C. variabilirostris) and the P5 dactylus that has more spiniform setae on the flexor margin: 28–41 (vs 13–30 and 18–29, respectively). Caridina choiseul sp. nov. is most similar to C. brachydactyla De Man, 1908 and C. peninsularis Kemp, 1918, but its P2 chela is stouter (2.0–2.7 times as long as wide vs 2.7–3.2 and 2.8–3.0, respectively) and the pre-anal carina which has a spine or not (vs always armed). Caridina choiseul sp. nov. looks like Caridina elongapoda Liang & Yan, 1977, but the pre-anal carina has a spine or not (vs always unarmed) and its P3 dactylus with 5–6 spiniform setae on the flexor margin in addition to the terminal one (vs 6–7). Caridina choiseul sp. nov. looks like C. mertoni Roux, 1911 and C. sundanella Holthuis, 1978, but the pre-anal carina has a spine or not (vs always unarmed) and its rostrum has 7–12 ventral teeth (vs 4–9 and 7–9, respectively).