Caridina typus H. Milne Edwards, 1837

Figs 2D, 10

Caridina typus H. Milne Edwards, 1837: 363, pl. 25, figs 4–5 (type locality: Mauritius).

Caridina exilirostris Stimpson, 1860: 98 (type locality: Okinawa (Loo Choo) Island, Ryukyu Islands, Japan).

Caridina typus f. typica Bouvier, 1925: 249–253, figs 271–297.

Caridina typus f. caledonica Bouvier, 1925: 253, figs 296–297 (type locality: New Caledonia).

Caridina typus – Richters 1880: 162, pl. 17, fig. 23. — De Man 1892: 367, pl. 21, fig. 22. — Holthuis 1965: 10–11, fig. 3. — Bossuyt et al. 2004: 480 (GenBank: AY708118). — Cai et al. 2006: 412– 418, figs 13–15 (partim).— Page et al. 2007: 648–650 (Genbank: DQ478558 – DQ478563). — de Mazancourt et al. 2019a: 166, 169–170.

Material examined

SOLOMON ISLANDS – Choiseul Island • 1 ♀, cl 3.8 mm; Creek 1; 06°59.085´S, 156°47.454´E; 132 m a.s.l.; 14 Oct. 2014; P. Gerbeaux, P. Keith and G. Marquet leg.; DNA voucher: CA1355; MNHN-IU- 2018-2824 • 1 ♀, cl 4.0 mm; same collection data as for preceding; DNA voucher: CA1356; MNHN-IU- 2018-2825 . – Kolombangara Island • 1 ♂, cl 3.9 mm; Sulumuni River; 08°02.253´S, 157°09.257´E; 148 m a.s.l.; 12 Nov. 2015; P. Keith, C. Lord and G. Marquet leg.; MNHN-IU- 2018-2826 .

FEDERATED STATES OF MICRONESIA • 1 ♀, cl 3.6 mm; Pohnpei Island, Nanpil River, estuary; 06°56.683´N, 158°12.550´E; 5 m a.s.l.; 13 Mar. 2012; M. Castelin, P. Gerbeaux, P. Keith, G. Marquet and L. Taillebois leg.; MNHN-IU- 2018-2837 • 1 ♀ ovig., cl 3.9 mm; same collection data as for preceding; MNHN-IU- 2018-2838 .

JAPAN • 1 ♀, cl 6.3 mm; Shikoku, Mugi, irrigation canal; 33°40.796´N, 134°26.024´E; 317 m a.s.l.; 16 Jun. 2017; M. Saito leg.; MNHN-IU- 2018-2827 • 1 ♀, cl 6.7 mm; same collection data as for preceding; DNA voucher: CA1917; MNHN-IU- 2018-2828 .

MADAGASCAR • 1 ♀, cl 4.5 mm; Antsatoko River; 13°36.660´S, 50°00.341´E; 29 m a.s.l.; 6 Jul. 2008; C. Ellien, E. Feunteun, N. Mary and T. Robinet leg.; DNA voucher: CA1038; MNHN-IU- 2018-2829 • 1 ♀ ovig., cl 6.9 mm; same collection data as for preceding; MNHN-IU- 2018-2830 • 1 ♀ ovig., cl 7.1 mm; same collection data as for preceding; MNHN-IU- 2018-2831 .

MALAYSIA • 3 ♂♂, cl 8.0– 8.5 mm; Pulau Langkavi, Sungai datai; 15 Mar. 2008; Schubart, Klaus and Koiler leg.; ZMB 28490 .

NEW CALEDONIA • 1 ♀ ovig., cl 6.8 mm; Pirogues River; 22°11.208´S, 166°43.292´E; 102 m a.s.l.; 10 Nov. 2016; G. Marquet, P. Tiberghien and V. de Mazancourt leg.; MNHN-IU- 2018-2832 • 1 ♀, cl 4.9 mm; Natoré River; 22°03.597´S, 166°53.983´E; 12 Nov. 2016; 5 m a.s.l.; G. Marquet, P. Tiberghien and V. de Mazancourt leg.; MNHN-IU- 2018-2833 .

PALAU • 1 ♀, cl 4.7 mm; Babeldaob Island, Ngerchokl River; 07°36.527´N, 134°36.958´E; 36 m a.s.l.; 27 Feb. 2011; M. Castelin, P. Gerbeaux, P. Keith, G. Marquet and L. Taillebois leg.; MNHN-IU- 2018-2839 • 1 ♀ ovig., cl 4.4 mm; same collection data as for preceding; MNHN-IU- 2018-2840 • 1 ♀ ovig., cl 4.6 mm; same collection data as for preceding; MNHN-IU- 2018-2841 .

PAPUA NEW GUINEA – New Britain • 1 ♀ ovig., cl 8.7 mm; Walindi River; 05°21.187´S, 150°02.699´E; 30 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU- 2018-2834 • 1 ♀ ovig., cl 5.8 mm; Rangihi swamp; 05°34.549´S, 149°928.943´E; 24 Oct. 2018; R. Causse, P. Keith and C. Lord leg.; MNHN-IU- 2018-2835 • 1 ♀ ovig., cl 6.4 mm; same collection data as for preceding; DNA voucher: CA2278; MNHN-IU- 2018-2836 .

SEYCHELLES • 1 ♀, cl 9.2 mm; Praslin Island, Nouvelle Découverte River; 04°19.200´S, 55°42.333´E; 16 m a.s.l.; 8 Oct. 2003; P. Bosc, H. Grondin, P. Keith and P. Valade leg.; MNHN-IU-2014-577 .

SOUTH AFRICA • 1 ♀ ovig., cl 10.1mm; Umtata River; 31°55.511´S, 29°08.199´E; 2 m a.s.l.; 13 Feb. 2018; L. Maliwa, M. Mlambo, G. Marquet and P. Tiberghien leg.; MNHN-IU- 2018-2843 • 1 ♂, cl 5.7 mm; Mpenjati River; 30°56.645´S, 030°13.660´E; 93 m a.s.l.; 15 Feb. 2018; P. Kubheka, N. McClurg, T. McClurg, L. Maliwa, M. Mlambo, G. Marquet and P. Tiberghien leg.; DNA voucher: CA2090; MNHN-IU- 2018-2844 .

VANUATU • 1 ♂, cl 3.9 mm; Epi Island, Buavinai River; 16°48.189´S, 168°11.084´E; 45 m a.s.l.; 27 Oct. 2014; A. Acou, D. Kalfatak, G. Marquet and M. Mennesson leg.; MNHN-IU- 2018-2842 .

Description

CEPHALOTHORAX. Suborbital angle indistinguishably fused with antennal spine. Pterygostomian margin subrectangular. Rostrum (Fig. 10m): short, 0.3–0.6 of cl, reaching from end of basal segment to end of third segment of antennular peduncle, unarmed dorsally, ventral margin with 0–4 teeth. Eyes well developed. Prominent antennular keel. Antennular peduncle slender, 0.42 (♀) – 0.54 (♂) times as long as carapace. Basal segment 0.50–0.54 times as long as length of the antennular peduncle, second segment 1.42–1.50 times as long as third. Stylocerite reaching 0.70–0.80 length of basal segment of antennular peduncle.

PEREIOPODS. Epipods on first four pereiopods. P1 (Fig. 10a): chela about 1.9–2.7 times as long as wide, movable finger 1.9–3.9 times as long as wide, 0.6–1.3 times length of palm; carpus 1.0–2.2 times as long as wide. P2 (Fig. 10b) more slender and longer than first pereiopod, with chela 2.4–3.3 times as long as wide: movable finger 3.8–5.4 times as long as wide, 1.3–1.8 times length of palm; carpus slender, 5.0–6.5 times as long as wide. P3 (Fig. 10c): stout, dactylus (Fig. 10e) 2.5–3.4 times as long as wide (terminal spiniform seta included), with 5–7 spiniform setae on flexor margin in addition to terminal one; propodus 7.9–10.0 times as long as wide, 3.6–4.6 times as long as dactylus. P5 (Fig. 10d): dactylus (Fig. 10f) 3.2–5.1 as long as wide, with 33–81 spinifrom setae on flexor margin; propodus 10.4–16.9 times as long as wide, 3.2–5.7 times as long as dactylus.

ABDOMEN. Third abdominal somite with moderarely convex dorsal profile. Sixth abdominal somite 0.43–0.48 times as long as carapace, 1.4 times as long as fifth somite, shorter than telson.

TELSON (Fig. 10i). 2.8 times as long as wide, with four to six pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with median process, rounded with 5–9 plumose intermediate setae subequal to lateral ones or slightly longer.

MALE PLEOPODS. Pl1 (Fig. 10j): endopod subrectangular, 3.6 times as long as wide, 0.44 times as long as exopod, with appendix interna, on subdistal outer margin, which reaches beyond distal end of endopod on a short length. Pl2 (Fig. 10k): appendix masculina elongated, reaching 0.59–0.76 times length of endopod; appendix interna reaching about 0.46–0.65 times appendix masculina length.

PRE- ANAL CARINA (Fig. 10g). High, unarmed.

UROPODAL DIAERESIS (Fig. 10h). With 15–22 spinules.

EGGS (Fig. 10l). Size: 0.38–0.54 × 0.23–0.32 mm.

Habitat

This species is found from the lower to higher course of rivers (5–317 m). It can be found in areas where the current speed is low, rich in vegetation debris, as well as in zones where the current is strong.

Colour pattern

The colour of the body can vary from pink-orange to blackish brown, sometimes with a brown to white stripe on the back.

Distribution

Caridina typus, the type species of the genus, has a very wide distribution in the Indo-West Pacific area, ranging from South Africa, Madagascar and the Seychelles to Japan, Malaysia, Philippines, Australia, Micronesia (Pohnpei), Papua New Guinea, Solomon Islands, New Caledonia, Vanuatu and Fiji. In contrast to what Holthuis (1965) and Chace (1997) stated, C. typus does not occur in Polynesia, but a species allied to C. jeani Cai, 2010 (see below).

Remarks

According to Chace (1997) and Cai et al. (2006) the type locality of C. typus is unknown. Bouvier (1925) ensures that type specimens have been caught on Mauritius Island but were lost following a move in 1918 caused by bombardments of Paris.

Our specimens fit well with the descriptions of this species occurring in Japan by Cai et al. (2006) by its short rostrum reaching near the end to the third segment of the antennular peduncle (vs to end of second segment of antennular peduncle according to Cai et al. (2006)), unarmed dorsally and armed ventrally, with 0–4 teeth (vs 1–4). P1 carpus 1.0–2.2 (vs. 1.6); P2 carpus 5.0–6.5 (vs 5.0–6.2). P3 dactylus with 5–7 spiniform setae (vs 5–7), propodus 3.6–4.6 as long as dactylus (vs 3.7–4.4); P5 dactylus with about 33–81 spiniform setae (vs 60–77), propodus 10.4–16.9 times long as width (vs 11–14) and propodus 3.2–5.7 times as long as dactylus (vs 3.3–3.7); Pl1 endopod elongate, with distinct appendix interna near distal end of endopod; pre-anal carina lacking spine; telson terminating in posteromedian projection, lateral pair subequal (vs subequal). Uropodal diaresis 15–22 (vs 19–24). Egg sizes 0.38–0.54 × 0.23– 0.32 (vs 0.45–0.48 × 0.23–0.26).