Caridina lobocensis, Cai & Choy & Ng, 2009

Cai, Yixiong, Choy, Satish & Ng, Peter K. L., 2009, Epigean And Hypogean Freshwater Shrimps Of Bohol Island, Central Philippines (Crustacea: Decapoda: Caridea), Raffles Bulletin of Zoology 57 (1), pp. 65-89 : 68-72

Caridina lobocensis , new species

( Figs. 2–4 )

Material examined. – Holotype: male, cl 5.7 mm, USC, tributary of Loboc River, Loboc, coll. Y. Cai, 19 Dec.2000.

Paratypes: Seventy males, cl 3.8–5.3 mm, 19 females, cl 3.9–7.5 mm, 83 ovigerous females, cl 5.3–7.2 mm, ZRC 2007.0283 , data same as holotype .

Description. – Rostrum ( Figs. 2A , 3A ) straight, reaching slightly beyond end of antennular peduncle; rostral formula: 2–4+10–12/3–7. Antennal spine fused with inferior orbital angle. Pterygostomian margin subrectangular.

Sixth abdominal somite 0.44 times of carapace, 1.4 times as long as fifth somite, distinctly shorter than telson. Telson ( Figs. 3B , 4A ) 2.6 times as long as wide, terminating in a projection, with 3 or 4 pairs of dorsal spinules and 1 pair of dorsolateral spinules; lateral pair of spines distinctly shorter than intermediate pairs of setae. Preanal carina (3I) high, lacking spine.

Eyes developed, anterior end reaching to 0.8 times length of basal segment of antennular peduncle. Antennular peduncle 0.55 times as long as carapace; basal segment of antennular peduncle as long as both of second and third segment lengths, anterolateral angle reaching 0.20 times length of second segment, second segment distinctly longer than third segment. Stylocerite reaching slightly beyond end of basal segment of antennular peduncle. Scaphocerite ( Fig. 2B ) 2.5 times as long as wide.

Incisor process of mandible ( Fig. 2C ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 2D ) broadly rounded, upper lacinia elongated, with a number of distinct teeth on inner margin, palp slender. Upper endites of maxilla ( Fig. 2E ) subdivided, palp short, scaphognathite tapering posteriorly with some long, curved setae at posterior end. Palp of first maxilliped ( Fig. 2F ) broadly triangular. Second maxilliped ( Fig. 2G ) typical of genus. Third maxilliped ( Fig. 2H ) reaching to end of antennular peduncle, with ultimate segment shorter than penultimate segment.

Epipods on first 4 pereiopods. First pereiopod ( Figs. 3C , 4D ) reaching to end of basal segment of antennular peduncle; merus 1.7–2.1 times as long as broad, slightly longer than carpus; carpus excavated anteriorly, shorter than chela, 1.1– 1.2 times as long as high; chela 2.2 times as long as broad; fingers distinctly shorter than palm. Second pereiopod ( Figs. 3D , 4E ) reaching to end of second segment of antennular peduncle; merus as long as carpus, 4.2–5.0 times as long as broad; carpus 1.1 times as long as chela, 2.3–2.4 times as long as high; chela 2.3–2.4 times as long as broad; fingers 1.6 times as long as palm. Third pereiopod ( Figs. 3E, F , 4F, G ) reaching slightly beyond end of scaphocerite, propodus 9–11 times as long as broad, 5.2–5.7 times as long as dactylus; dactylus 2.7–3.0 times as long as wide (spines included), terminating in 2 very strong claws, with 4–6 accessory spines on its flexor margin. Fifth pereiopod ( Figs. 3G, H , 4H, I ) reaching beyond end of second segment of antennular peduncle, propodus 13–18 times as long as broad, 5.5–5.6 times as long as dactylus, dactylus 2.7–3.0 times as long as wide (spinules included), terminating in 2 large claws, with 26–30 spinules on its flexor margin.

Endopod of male first pleopod ( Fig. 4B ) subtriangular, half length of exopod, appendix interna stout, exceeding end of endopod. Appendix masculina of male second pleopod ( Fig. 4C ) 2/3 length of endopod, with appendix interna reaching base of distal one-third of appendix masculina.

Uropodal diaeresis ( Fig. 3J ) with 18 movable spinules.

Ovigerous females with eggs sized 0.45 × 0.25 mm.

Habitat. – Caridina lobocensis , new species, was collected from a tributary of the Loboc River near Loboc town, Bohol Island in central Philippines. The shrimps were living among submerged grass at edges of the tributary.

Etymology. – The new species is named after its type locality- Loboc River, Bohol Island, the Philippines.

Remarks. – Based on the form of the rostrum, the high preanal carina, the large number of uropodal teeth and the form of the telson, C. lobocensis , new species, belongs to the C. weberi species group. In the group, it is most similar to C. okinawa Cai & Shokita, 2006b , from Okinawa Island of the Ryukyu Islands, southern Japan, in term of the rostral formula, the long stylocerite, the broad scaphocerite, the stout first pereiopod, and its short fingers, and the third to fifth pereiopods ending in two claws. However, it could be easily separated from C. okinawa by the well developed eyes (vs. eyes less developed, with a short eye stalk and small cornea) and the longer rostrum which reaches slightly beyond end of antennular peduncle (vs. reach to end of second segment of antennular peduncle) ( Figs. 2–4 ; cf. Cai & Shokita, 2006b: Fig. 12 ). Caridina lobocensis also resembles another Ryukyuan species, C. macrodentata Cai & Shokita, 2006b , in the form of the dactylus of the third to fifth pereiopods, Nevertheless, it could be differentiated from the latter by the longer rostrum, which reaches slightly beyond the end of the antennular peduncle (vs. reaches middle of the second segment of the antennular peduncle) and the long stylocerite (reaches to or slightly beyond the end of the basal segment of the antennular peduncle vs. does not reaches) ( Figs. 2 , 3 ; cf. Cai & Shokita, 2006b: Figs. 13, 14).

Figures

Fig. 2. Caridina lobocensis, new species: A, cephalothorax and cephalic appendages, lateral view; B, scaphocerite; C, mandible; D, maxillula; E, maxilla; F, first maxilliped; G, second maxilliped; H, third maxilliped. Scale bars: A = 2 mm, B–H = 1 mm (female, cl 6.9 mm, Paratype, ZRC, Philippines).

Fig. 3. Caridina lobocensis, new species: A, cephalothorax and cephalic appendages, lateral view; B, distal portion of telson; C, first pereiopod; D, second pereiopod; E, third pereiopod; F, dactylus of third pereiopod; G, fifth pereiopod; H, dactylus of fifth pereiopod; I, preanal carina; J, uropodal diaeresis. Scale bars: A = 2 mm, B, F, H, J = 0.2 mm; C–E, G = 1 mm; I = 0.5 mm (male, cl 5.7 mm, paratype, ZRC, Bohol Island, Philippines).

Fig. 4. Caridina lobocensis, new species: A, telson; B, endopod of male first pleopod; C, appendix masculina and appendix interna of male second pleopod; D, first pereiopod; E, second pereiopod; F, third pereiopod; G, dactylus of third pereiopod; H, fifth pereiopod; I, dactylus of fifth pereiopod. Scale bars: A, D–F, H = 1 mm; B, C, G, I = 0.2 mm (A–C, male, cl 5.7 mm, paratype, ZRC, Bohol Island, Philippines; D–I, female, cl 6.9 mm, paratype, ZRC, Bohol Island, Philippines).

Fig. 12. Caridina camaro, new species: A, cephalothorax and cephalic appendages, lateral view; B, telson; C, distal portion of telson; D, first pereiopod; E, second pereiopod; F, third pereiopod; G, dactylus of third pereiopod; H, fifth pereiopod; I, dactylus of fifth pereiopod; J, uropodal diaeresis. Scale bars: A, B = 1 mm; C = 0.2 mm; D–F, H = 0.5 mm; G, K = 0.1 mm; B, F, H = 0.1 mm; C–E, G = 0.5 mm; I, J = 0.2 mm (females, cl 4.3 mm, holotype, USC, Cave Camaro, Batuan).