Caridina leptopoda, de Mazancourt & Freitag & von Rintelen & Manuel-Santos & von Rintelen, 2023

de Mazancourt, Valentin, Freitag, Hendrik, von Rintelen, Kristina, Manuel-Santos, Marivene & von Rintelen, Thomas, 2023, Updated Checklist of the Freshwater Shrimps (Decapoda: Caridea: Atyidae) of Mindoro Island, the Philippines, with a Description of a New Species of Caridina, Arthropoda 1 (4), pp. 374-397 : 387-388

Caridina leptopoda sp. nov.

( Figure 4)

Non Caridina gracilirostris —Estampador, 1937 [ 18]: 485 (part?); 1959 [ 19]: 19 (part?).—Chace, 1997 [ 20]: 10 (part).

Material examined:

Holotype: PHILIPPINES — 1 ♀, cl 5.9 mm; Municipality Victoria, Bgy. Malayas, W coast Naujan Lake, littoral Vallisneria beds, Oriental Mindoro; 13.1497, 121.3133; 22.02.2010; coll. Freitag, Pangantihon; NMCR-12001 ( DNA 3311).

Paratypes: PHILIPPINES — 1 ♀, cl 5.5 mm; same data asfor holotype ( DNA 3312).— 1 ♀ ov., cl 4.8 mm, 1 ♂, cl 4.2 mm, 1 specimen; Imugaan River, W-coast Fabrica, Fabrica/Sagay Municipality, Negros Occidental; 10.8824; 123.3552; coll. Richter, Stelbrink; NMCR-12002 (1 ♂), ZMB 29569 ( DNA 925, 926 and 927).

Description:

Cephalothorax. Antennal spine distinctly below the suborbital angle. Pterygostomian margin rounded. Rostrum ( Figure 4p): long, curved upward, 1.6–1.8 of cl, much longer than the scaphocerite, armed with 8–11 teeth on the dorsal margin, 0–1 of them situated on the carapace behind the orbital margin, unarmed part length 0.5–0.8 of the armed part, ventral margin with 25–33 teeth. Rostral formula: (0–1) 8–11/25–33.

Eyes well developed, anterior end reaching 0.51 the length of the basal segment of the antennular peduncle. Antennular peduncle 0.76(♀)–0.94(♂) times as long as the carapace. Second segment longer than the third. Stylocerite 0.85–0.95 of the basal segment of the antennular peduncle.

Pereiopods. Epipods on first four pereiopods. P1 ( Figure 4a): chela 2.1–2.2 times as long as wide, movable finger 3.5–3.8 times as long as wide, 1.2–1.4 times the length of the palm; carpus 1.9–2.2 times as long as wide. P2 ( Figure 4b) more slender and longer than P1 with chela 2.3–2.6 times as long as wide: movable finger 4.1–5.3 times as long as wide, 1.5–1.8 times the length of the palm; carpus 3.6–5.2 times as long as wide. P3 ( Figure 4c): slender, dactylus ( Figure 4e) long, 3.5–5.1 timesas long as wide (terminal spiniform seta included) with 10–11 spiniform setae on the flexor margin including the terminal spiniform seta; propodus 13.8–16.9 times as long as wide, 4.0–4.3 times as long as the dactylus. P5 ( Figure 4d): dactylus ( Figure 4f) 3.9–6.3 times as long as wide with 40–42 spiniform setae on the flexor margin; propodus 15.3–19.5 times as long as wide, 3.8–4.3 times as long as the dactylus.

Abdomen. Third abdominal somite with moderately convex dorsal profile. Sixth abdominal somite about 0.71 times the carapace length and 2.4–2.6 timesas long as the fifth somite, reaching 0.98 the length of the telson.

Telson ( Figure 4i –l) with 3–4 pairs of dorsal spinules and one pair of dorsolateral spinules; posterior margin with a median process, triangular with 1–2 pairs of lateral setae and 0–1 pair of short intermediate simple setae shorter than the lateral ones.

Pl1 ( Figure 4m): Endopod of male triangular, 1.96 times as long as wide, reaching 0.22 time the exopod, without an appendix.

Pl2 ( Figure 4n): Appendix masculina on the second pleopod reaching 0.53 the length of the endopod; appendix interna reaching 0.38 time the appendix masculina.

Preanal carina ( Figure 4g) armed with an acute spine.

Uropodal diaeresis ( Figure 4h) straight and short, with 7–8 spinules.

Eggs ( Figure 4o) small, 0.43–0.44 × 0.27–0.28 mm (developed).

Habitat: This species is found in the lower course of rivers, sometimes in brackish conditions.

Distribution: On Mindoro: Locality no. 17. Known only from the Philippines (Mindoro, Negros).

Etymology: From the Greek leptos, “slender”, and podos, “foot”, referring to its long third and fifth pereiopods.

Remarks:

Reported from Mindoro as Caridina gracilirostris by Chace (1997) [ 20]. This new species indeed resembles C. gracilirostris as re-described by de Mazancourt et al. (2020) [ 65] from its long rostrum with few post-orbital teeth, its short P1 carpus, and its spine on the pre-anal carina but it can be easily distinguished by its longer P3 dactylus 3.5–5.1 (vs. 3.3–3.8) times as long as wide with more spiniform setae on its P3 dactylus 10–11 (vs. 7–10) and P5 dactylus 40–42 (vs. 26–33) and its longer P3 propodus 15.8–16.9 (vs. 11.7–14.0) times as long as wide. It also looks like Caridina neglecta from its long rostrum and its spine on the pre-anal carina but can be easily distinguished by the absence of appendix interna on the endopod of its first male pleopod, its shorter P1 and P2 carpi 1.9–2.2 (vs. 2.3–3.1) and 3.6–5.2 (vs. 5.2–6.4) times as long as wide, respectively, and its longer P3 dactylus 4.8–5.1 (vs. 3.3–4.7) with more spiniform setae 10–11 (vs. 5–7). This new species is also similar to Caridina gracilima as re-described by Cai and Ng (2007) [ 78] from its long dactyli on pereiopods 3 and 5 but they can be separated by its higher number of teeth on the ventral margin of its rostrum 25–33 (vs. 19–24), the presence of a spine on its pre-anal carina (vs. absent), and its smaller eggs 0.43–0.44 × 0.27–0.28 mm (vs. 0.55–0.66 × 0.35–0.40 mm). None of our male specimens show an appendix interna on the endopod of the first pleopod, whereas Chace (1997) [ 20] found a rudimentary one on three of the eight males he examined. One can hypothesize variation of this character depending on the breeding season of the species since Chace’s specimens were collected in December whereas ours were collected in May.