Caridina mindanao, Shokita, 2006

Shokita, Yixiong Cai Shigemitsu, 2006, Report On A Collection Of Freshwater Shrimps (Crustacea: Decapoda: Caridea) From The Philippines, With Descriptions Of Four New Species, Raffles Bulletin of Zoology 54 (2), pp. 245-270 : 259-263

Caridina mindanao , new species

( Figs. 7-9 )

Material examined. – Holotype: male, cl 3.3 mm, NSMT, ( NSMT), Lake Mainit , Mindanao, Philippines, 24 Jul.1985, coll. S. Shokita. Paratypes: 5 females, cl 3.5-4.0 mm, 5 ovig. females, cl 3.7-3.8 mm, UR; 3 females, cl 3.3-3.7 mm, 3 ovig. females, cl 3.7-3.9 mm, ZRC, data same as holotype .

Description. – Rostrum ( Fig. 7A ) long, upturn anteriorly, longer than carapace length, reaching beyond end of scaphocerite; rostral formula: 0-1+7-15+1/16-23. Antennal spine lower than inferior orbital angle. Pterygostomian angle broadly rounded.

Third abdominal somite ( Fig. 7B ) with strongly convex dorsal profile, sub-rectangular in form. Sixth abdominal somite 0.78 times of carapace, 2.2 times as long as fifth somite, as long as telson. Telson ( Fig. 8A, B ) 3.8 times as long as wide, not terminating in a projection, with 3-4 pairs of dorsal spinules and one pair of dorsolateral spinules; distal margin with 2 pairs of spines, lateral pair of dorsal spines distinctly longer than intermediate pair of spines. Preanal carina ( Fig. 9I ) small, lacking spine.

Eyes well developed, anterior end reaching to 0.6 times length of basal segment of antennular peduncle. Antennular peduncle 0.94 times as long as carapace; basal segment of antennular peduncle longer than sum of second and third segment length, anterolateral angle pointed, reaching 0.25 length of the second segment, second segment distinctly longer than third segment. Stylocerite reaching to 0.9 length of basal segment of antennular peduncle. Scaphocerite ( Fig. 7C ) 4.4 times as long as wide.

Incisor process of mandible ( Fig. 7D ) ending in irregular teeth, molar process truncated. Lower lacinia of maxillula ( Fig. 7E ) broadly rounded, upper lacinia elongated, with a number of distinct teeth on inner margin, palp slender. Upper endites of maxilla ( Fig.7F ) subdivided, palp short, scaphognathite tapering posteriorly with some long, curved setae at posterior end. Palp of first maxilliped ( Fig. 7G ) broadly triangular; flagellum short. Second maxilliped ( Fig. 7H ) typical. Third maxilliped ( Fig. 8I ) reaching to end of second segment of antennular peduncle, with ultimate segment distinctly shorter than penultimate segment.

Epipods on first four pereiopods. First pereiopod ( Fig. 8C , 9A ) reaching to anterior margin of eye stalk; ischium as long as merus; merus 2.2 times as long as broad, slightly longer than carpus; carpus excavated anteriorly, shorter than chela, 1.2-1.4 times as long as high; chela 2.1-2.5 times as long as broad; fingers as long as palm. Second pereiopod ( Fig. 8D , 9B ) reaching middle of second segment of antennular peduncle; ischium as long as merus; merus shorter than carpus, 3.5-3.9 times as long as broad; carpus shorter than chela, 3.1-3.2 times as long as high; chela 2.4-2.6 times as long as broad; fingers as long as palm. Third pereiopod ( Fig 8E, F , 9C, D ) reaching to end of antennular peduncle, propodus 12-13 times as long as broad, 3.0-3.2 times as long as dactylus; dactylus slender, 4.4-4.5 times as long as wide (spines included), with 10 accessory spines on its flexor margin. Fifth pereiopod ( Fig. 8G, H , 9E, F ) reaching slightly beyond end of second segment of antennular peduncle, propodus 13-15 times as long as broad, 3.0-3.2 times as long as dactylus, dactylus 4.2-4.5 times as long as wide (spinules included), with 36-38 no-denticulate spinules on its flexor margin. Endopod of male first pleopod ( Fig. 9G ) subtriangular, 1/4 length of exopod, no appendix interna. Appendix masculina of male second pleopod ( Fig. 9H ) half length of endopod.

Uropodal diaeresis ( Fig. 8J ) with 10 movable spinules.

Ovigerous females with egg sized 0.7-0.8x 0.45-0.55 mm in diameter.

Habitat. – Caridina mindanao , new species, was collected from the Lake Mainit, Mindanao Island in southern Philippines.

Etymology. – The new species is named after the type locality – Lake Mainit, Mindanao Island in southern Philippines, and used as a noun in apposition.

Remarks. – Taking into consideration the form of the rostrum and endopod of the male first pleopod, C. mindanao , new species, is morphologically most similar to C. gracilipes De Man, 1892 . It can easily be differentiated from C. gracilipes by its much longer sixth abdominal segment which is 2.2 times as long as the fifth (vs. 1.9 times in C. gracilipes ), the rostral formula of 0-1+11-15+1/16-23 (vs. 2+13-20+1-2/13- 18), and the larger egg size (0.7-0.8x 0.45-0.55 mm vs. 0.42- 0.53x 0.23-0.33 mm).

Distribution. – Philippines.

FAMILY PALAEMONIDAE

Figures

Fig. 7. Caridina mindanao, new species, ovig. female, cl 3.8 mm, Mindanao, Philippines: A, cephalothorax and cephalic appendages; B, abdomen and telson; C, scaphocerite; D, mandible; E, maxillula; F, maxilla; G, first maxilliped; H, second maxilliped. Scale bars: A, B = 1 mm; C, H = 0.5 mm.

Fig. 8. Caridina mindanao, new species, ovig. female, cl 3.8 mm, Mindanao, Philippines: A. telson; 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, third maxilliped; J, diaeresis. Scale bars: A, C-E, G, I = 0.5 mm; B, F, H = 0.1 mm; J = 0.2 mm.

Fig.9. Caridina mindanao, new species, male, cl 3.3 mm, Mindanao, Philippines: A, first pereiopod; B, second pereiopod; C, third pereiopod; D, dactylus of third pereiopod; E, fifth pereiopod; F, dactylus of fifth pereiopod; G, male first pleopod; H, appendix masculina and appendix interna of male second pleopod; I, preanal carina. Scale bars: A-C, E, I = 0.5 mm; D, F = 0.1 mm; G, H = 0.2 mm.