Caridina intermedia sp. nov.

urn:lsid:zoobank.org:act: 7A52CFEB-5BA8-483F-9C70-69958430DF8E

Figs 2I, 7, 25F

Caridina sp. Sol.2 – Page et al. 2007: 649 (GenBank: DQ478545).

Caridina sp. 1 Solomon – de Mazancourt et al. 2019a: 166, 169–170.

Etymology

Caridina intermedia sp. nov. was named for its intermediate morphometry between those of C. brevidactyla and C. grandirostris .

Material examined

Holotype

SOLOMON ISLANDS • ♀, cl 5.4 mm; Choiseul Island, Gu’ma River; 07°01.764´S, 156°49.899´E; 50 m a.s.l.; 17 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20840.

Paratypes

SOLOMON ISLANDS – Choiseul Island • 1 ♀ ovig., cl 5.4 mm; Lokasereke River; 06°58.024´S, 156°47.861´E; 13 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; MNHN-IU-2014-20841 • 1 ♀ ovig., cl 4.9 mm; same collection data as for preceding; MNHN-IU-2014-20842 • 1 ♂, cl 3.4 mm; same collection data as for preceding; MNHN-IU-2014-20843 • 1 ♂, cl 3.4 mm; Pisuku River, downstream; 06°58.848´S, 156°46.582´E; 12 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; DNA voucher: CA1326; MNHN-IU-2014-20844 • 1 ♂, cl 3.5 mm; same collection data as for preceding; MNHN-IU- 2014-20845 • 1 ♂, cl 3.7 mm; same collection data as for preceding; MNHN-IU-2014-20846 . – Kolombangara Island • 1 ♂, cl 3.5 mm; Poitete River; 07°52.413´S, 157°07.982´E; 15 Nov. 2015; P. Keith, C. Lord and G. Marquet leg.; DNA voucher: CA1499; MNHN-IU-2014-20847 . – Vella Lavella Island • 1 ♂, cl 3.1 mm; Vala Kadju River; 07°49.860´S, 156°42.644´E; 28 Oct. 2016; P. Keith and C. Lord leg.; MNHN-IU-2014-20848 • 1 ♀ ovig., cl 3.9 mm; same collection data as for preceding; MNHN-IU-2014-20849 • 1 ♂, cl 2.8 mm; Joroveto River; 07°49.918´S, 156°42.887´E; 28 Oct. 2016, P. Keith and C. Lord leg.; MNHN-IU-2014-20850 • 1 ♀ ovig., cl 3.9 mm; same collection data as for preceding; MNHN-IU-2014-20851 . – Isabel Island • 1 specimen; Rakata River; 15 m a.s.l.; 07.64456° S, 158.71918° E; 27 Oct. 2019; P. Keith, C. Lord, R. Causse and D. Boseto leg.; DNA voucher: CA2509; MNHN • 1 specimen; same collection data as for preceding; DNA voucher: CA2510; MNHN .

Other material

PAPUA NEW GUINEA – New Britain • 1 ♂, cl 4.1 mm; Ore River; 05°43.145´S, 49°34.128´E; 25 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU-2014-20852 • 1 ♀ ovig., cl 5.7 mm; same collection data as for preceding; MNHN-IU-2014-20853 • 1 ♀ ovig., cl 6.3 mm; same collection data as for preceding; MNHN-IU-2014-20854 • 1 ♀ ovig., cl 5.7 mm; same collection data as for preceding; MNHN-IU-2014-20855 • 1 ♂, cl 4.3 mm; Garu road; 05°27.278´S, 149°58.415´E; 26 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU-2014-20856 • 1 ♀, cl 4.5 mm; same collection data as for preceding; MNHN-IU-2014-20857 • 1 ♂, cl 4.2 mm; Galuku River; 05°45.187´S, 150°35.001´E; 20 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU-2014-20858 • 1 ♀ ovig., cl 5.9 mm; same collection data as for preceding; MNHN-IU-2014-20859 • 1 ♀ ovig., cl 5.4 mm; Kokori River; 05°42.650´S, 150°37.693´E; 22 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU-2014-20860 • 1 ♀ ovig., cl 5.7 mm; Rangihi swamp; 05°34.549´S, 149°28.943´E; 24 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU-2014-20861 .

Comparative material

Caridina longirostris (H. Milne Edwards, 1837)

See de Mazancourt et al. 2018c.

Caridina appendiculata (Jalihal & Shenoy, 1998)

See de Mazancourt et al. 2018c.

Caridina brevidactyla (Roux, 1919)

See de Mazancourt et al. 2018c.

Caridina gracilipes (De Man, 1892)

See de Mazancourt et al. 2018c.

Description

CEPHALOTHORAX. Carapace (Fig. 7m) smooth, glabrous, with sharp antennal spine placed at lower orbital angle. Pterygostomial margin subrectangular. Long rostrum, 1.1–1.8 of cl, curved up distally, reaching well beyond scaphocerite. 16–26 dorsal teeth closely set, leaving 0.4–1.3 unarmed distally except for one or two subapical teeth, 1–3 post-orbital teeth present. 9–20 teeth present of 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 11–16. Eyes well developed, anterior end reaching to 0.60–0.63 length of basal segment of antennular peduncle. Antennular peduncle 0.69 (♀) – 0.90 (♂) times as long as carapace. Anterolateral angle pointed reaching to 0.37 length of the second segment; second segment distinctly longer than third segment. Stylocerite reaching to 0.83–0.90 length of basal segment of antennular peduncle.

PEREIOPODS. Slender P1 (Fig. 7a): chela about 2.0–2.4 times as long as wide, dactylus 3.4–4.2 times as long as wide, 1.1–1.5 length of palm; carpus 2.4–3.1 times as long as wide, with shallow excavation on anterior margin. P2 (Fig. 7b) more slender and longer than first pereiopod: chela 2.3–2.9 times as long as wide, dactylus 4.1–5.4 times as long as wide, 1.1–1.6 times length of palm; carpus 5.8–6.7 times as long as wide. P3 (Fig. 7c): dactylus (Fig. 7e) 2.9–4.2 times as long as wide, with 6–7 spiniform setae on flexor margin in addition to terminal one; propodus 15.3–21.7 times as long as wide, 4.4–6.6 times as long as dactylus. P5 (Fig. 7d): dactylus (Fig. 7f) 4.1–5.6 long as wide, with 31–59 spiniform setae on flexor margin; propodus 18.9–27.9 times as long as wide, 4.7–6.1 as long as dactylus.

ABDOMEN. Typical dorsal hump over third abdominal somite, sixth abdominal somite 0.74 as long as carapace, 1.9 times as long as fifth somite, 1.0 times as long as telson.

TELSON (Fig. 7i). 3.8 times as long as wide, with four pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with median process, distal setae short, lateral pair slightly longer than intermediate setae (4).

MALE PLEOPODS. Pl1 (Fig. 7j): endopod subtriangular, 2.2 times as long as wide, 0.22 times as long as exopod, with appendix interna placed on subdistal outer margin. Pl2 (Fig. 7k): appendix masculina reaching 0.55 times length of endopod; appendix interna reaching 0.90 of appendix masculina.

PRE- ANAL CARINA (Fig. 7g). With spine.

UROPODAL DIAERESIS (Fig. 7h). With 9–14 spinules.

EGGS (Fig. 7l). Size: 0.33–0.43 × 0.20–0.25 mm.

Habitat

All specimens were collected in a typical brackish water environment (brackish water pool or lower part of rivers, near the estuary). In rivers of Solomon Islands, C. intermedia sp. nov. is syntopic with C. brevidactyla and C. appendiculata .

Colour pattern (Fig. 25F)

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

Distribution

Caridina intermedia sp. nov. is known from the Solomon Islands (Choiseul, Kolombangara, Vella Lavella and Isabel) and Papua New Guinea (New Britain).

Remarks

Caridina intermedia sp. nov. differs from C. longirostris by its longer P1 and P2 carpus, respectively 2.4–3.1 (vs 1.4–1.8 in C. longirostris) and 5.8–6.7 (vs 4.0–4.2) times as long as wide, a stouter P3 dactylus 2.9–4.2 (vs 4.0–4.8) times as long as wide, with propodus 4.4–6.6 (vs 3.4–4.1) times as long as dactylus, and a stouter P5 propodus, 4.1–5.6 (vs 3.2–3.5) times as long as dactylus. C. intermedia sp. nov. has an appendix interna on the endopod of the male first pleopod (vs none).

Caridina intermedia sp. nov. differs from C. appendiculata by its greater number of teeth on the proximal part of the dorsal margin of the rostrum, 16–26 closely set (vs 12–17 teeth somewhat irregular spaced in C. appendiculata), greater number of dorsal teeth before the first ventral teeth 11–16 (vs 8–12) and a slightly greater number of spiniform setae on the dactylus of the fifth pereiopod 31–59 (vs 33–44).

Caridina intermedia sp. nov. differs from C. gracilipes by its longer P2 carpus, 5.8–6.7 (vs 4.4–5.9 in C. gracilipes), by a lower number of spiniform setae on the dactylus of the third pereiopod, 6–7 (vs 9–10), with its more slender P3 propodus, 4.4–6.6 times as long as dactylus (vs 3.8–4.6), and its longer and more slender P5 propodus, 18.9–27.9 times as long as wide (vs 16.2–19.3).

Caridina intermedia sp. nov. is similar to C. grandirostris and C. brevidactyla by its rostrum with a similar number of dorsal teeth, 16–26 (vs 17–21 in C. grandirostris and 17–30 in C. brevidactyla). However, even though C. intermedia sp. nov. like C. grandirostris always has a pre-anal carina with a spine, C. brevidactyla never has one. C. intermedia sp. nov. can be separated from C. grandirostris by its greater P3 dactylus, 2.9–4.2 (vs 2.3–2.9 in C. grandirostris), its longer P3 propodus, 15.3–21.7 times as long as wide (vs 13–15), and its longer P5 propodus, 18.9–27.9 times as long as wide (vs 13.4–16.1).