Caridina paratypus sp. nov.

urn:lsid:zoobank.org:act: 5E893FC0-9914-4441-BBD4-7824C0D5747D

Figs 2Q, 22

Caridina cf. jeani – de Mazancourt et al. 2019a: 166, 169–170.

Etymology

This new species is named after its resemblance to C. typus.

Material examined

Holotype

SOLOMON ISLANDS • ♂, cl 5.0 mm; Malaita Island, Wairahuta River; 09°16.960´S, 161°07.287´E; 250 m a.s.l.; 17 Jun. 2015; D. Boseto leg.; DNA voucher: CA1999; MNHN-IU- 2018-2925.

Paratypes

VANUATU • 1 ♀ ovig., cl 6.2 mm; Epi Island, Buavinai River; 16°47.908´S, 168°11.3654´E; 28 Oct. 2014; 117 m a.s.l.; A. Acou, D. Kalfatak, G. Marquet and M. Mennesson leg.; DNA voucher: CA1371; MNHN-IU- 2018-2926 .

Description

CEPHALOTHORAX. Suborbital angle indistinguishably fused with antennal spine. Pterygostomian margin broadly subrectangular. Rostrum (Fig. 22m): straight, short, 0.4 of cl, reaching to near middle of second segment of antennular penduncle, unarmed dorsally, ventral margin with 0–5 teeth. Eyes well developed. Antennular peduncle 0.51 (♀) – 0.60 (♂) times as long as carapace. Anterolateral angle reaching 0.40 length of second segment, second segment shorter than third segment. Stylocerite reaching near basal segment of antennular peduncle.

PEREIOPODS. Epipods on first four pereiopods. P1 (Fig. 22a): chela about 1.9–2.1 times as long as wide, movable finger 2.1–2.2 times as long as wide, 0.7 times length of palm; carpus 1.5–16 times as long as wide. P2 (Fig. 22b) more slender and longer than first pereiopod, with chela 2.5–2.8 times as long as wide: movable finger 4.8–4.9 times as long as wide, 1.7–1.8 times length of palm; carpus slender, 5.4–5.9 times as long as wide. P3 (Fig. 22c): stout, dactylus (Fig. 22e) 3.2–3.9 times as long as wide (terminal spiniform seta included), with 7 spiniform setae on flexor margin in addition to terminal one; propodus 11.1–11.3 times as long as wide, 4.4–4.6 times as long as dactylus, merus bearing long setae on ventral margin. P5 (Fig. 22d): dactylus (Fig. 22f) 5.6–6.6 times as long as wide, with 59–60 spiniform setae on flexor margin; propodus 16.2–18.1 times as long as wide, 3.7–4.4 times as long as dactylus, merus bearing long setae on ventral margin.

ABDOMEN. Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite 0.46 times as long as carapace, 1.5 times as long as fifth somite, shorter than telson.

TELSON (Fig. 22i). 2.3 times as long as wide, with five or six pairs of dorsal spinules and pair of dorsolateral spinules; posterior margin with median process, rounded, with 10–11 plumose intermediate setae longer than lateral ones.

MALE PLEOPODS. Pl1 (Fig. 22j): endopod subrectangular, 3.2 times as long as wide, reaching 0.54 length of endopod, with appendix on subdistal outer margin which reaches slightly beyond distal end of endopod on short length. Pl2 (Fig. 22k): appendix masculina reaching 0.58 times length of endopod; appendix interna reaching 0.41 times length of appendix masculina.

HIGH PRE- ANAL CARINA (Fig. 22g). Unarmed.

UROPODAL DIAERESIS (Fig. 22h). With 17–19 spinules.

EGGS (Fig. 22l). Size: 0.50–0.54 × 0.29–0.31mm.

Habitat

This species is largely rheophile and prefers fresh and well-oxygenated waters from the middle to upper course of rivers (117–250 m a.s.l.).

Colour pattern

Unknown.

Distribution

This species occurs in the Solomon Islands (Malaita) and Vanuatu (Epi).

Remarks

This new species looks like C. typus by its unarmed dorsal rostrum and its elongate P2 carpus, 5.4–5.9 times as long as wide (vs 5.0– 6.5 in C. typus), but is easily distinguished by its longer P5 dactylus, 5.6–6.6 (vs 3.6–5.1), and its telson with 10–11 plumose intermediate setae longer than lateral ones (vs 5–8 smooth intermediate setae subequal to lateral ones).

This new species also looks like C. jeani by its unarmed dorsal rostrum and its telson with 10–11 plumose intermediate setae longer than lateral ones (vs 6–8 in C. jeani), but it is easily distinguished by its longer P3 dactylus, 4.4–4.6 times as long as wide (terminal spiniform seta included), with 7 spiniform setae on the flexor margin in addition to the terminal one (vs 1.6 with 5 spiniform setae), and by its shorter appendix masculine on the second male pleopod, 0.58 of the length ofthe endopod (vs 0.80).

In the same way as for the C. typus group, we include in the C. weberi group species with or without dorsal teeth on their rostrum. The length of setae on the telson (namely long and plumose terminal setae on the telson clearly longer than lateral ones) is a better criterion to characterize this group.