Caridina gracilirostris De Man, 1892

Cai, Y. & Ng, P. K. L., 2007, A revision of the Caridina gracilirostris De Man, 1892, species group, with descriptions of two new taxa (Decapoda; Caridea; Atyidae), Journal of Natural History 41 (25 - 28), pp. 1585-1602 : 1586-1595

Caridina gracilirostris De Man, 1892

( Figures 1 , 2 )

Caridina gracilirostris De Man 1892, p 399 (part), Plate 25, Figure 31a–c [type locality: river near Maros , Sulawesi (Celebes), Indonesia].

Caridina gracilirostris: Kemp 1918, p 282 ; Blanco 1935, p 32, Figures 11–17; Riek 1953, p 121; Holthuis 1965, p 23 (part); 1978, p 35 (part); Johnson 1961, p 124, Figures 1 , 2 ; Richard and Chandran 1994, p 242; Chace 1997, p 10 (part); Jalihal and Shenoy 1998, p 128; Cai and Ng 2001, p 674, Figure 7; Wowor, Cai, and Ng 2004, p 341, Figure 5Q ; Cai and Shokita 2006a, p 250 ; 2006b, p 2135.

Caridina pseudogracilirostris Thomas, Pillai, and Pillai 1976, p 871 , Figure 1 [type locality: Cochin backwater, India].

Material examined

Lectotype (here designated): male, cl 3.5 mm, ZMA DE102645, river near Maros, Sulawesi (Celebes), Indonesia, leg. M. Weber, 1888 . Paralectotypes: two ovigerous females, cl 5.6–5.7 mm, same data as lectotype ; one male, cl 3.7 mm, one female, cl 4.1 mm, one ovigerous female, cl 4.6 mm, eggs 0.4× 0.25 mm, RMNH D1076 , river near Balangnipa, leg. M. Weber, 15–21 October 1888 ; two males, cl 3.7–3.8 mm, one ovigerous female, cl 5.0 mm, eggs 0.40× 0.25 mm, MNHN Na 723, river near Balangnipa, leg. M. Weber, 15–21 October 1888, exchanged from Amsterdam Museum, 1911 .

Other material. Nineteen males, 15 ovigerous females, BNHM 704c, Menado, Sulawesi, Indonesia, coll. D. Wire, 1927; 56 females, four juveniles, BNMH 704 c, Menado , Sulawesi, coll. D. Wire, 1927; Molucca : one male, cl 5.2 mm, one female, cl 6.3 mm, ZRC, Sungei Dodaga , Halmahera, September 1994 , coll. D. Robb; New Guinea : one male, cl 4.1 mm, one female, cl 4.8 mm, ZRC, brackish water at river mouth of Ajkwa River , Irian Jaya, Indonesia, coll. D. L. Rahayu, 30 May 2000 ; three females, SMF 8354 , Wokam , Aru Islands, Indonesia, coll. S. Merton, 16 March 1908 ; one male, BNHM 704 b, Wakamar , Wokam, Aru Islands, Indonesia, coll. S. Merton, 16 March 1908 ; one female, one ovigerous female, BNMH 704 a, New Guinea, Indonesia ; one male, BNMH 704 b, Wakamar , Wokam, Aru Islands, Indonesia, coll. H. Merton, 1919; Lesser Sunda Islands : eight males, RMNH 30485 , Bondokodi River at bridge near Kodi, West Sumba, Indonesia, 31 July 1949 ; two females, one ovigerous female, RMNH 30486 , Bondokodi River 1–2 km above the bridge near Kodi, West Sumba, Indonesia, 2 August 1949 ; Borneo : nine males, cl 2.3–3.0 mm, 12 females, cl 2.4–3.3 mm, five ovigerous females, cl 3.7– 5.0 mm, ZRC, Kalimantan Barat, Kabupaten Sambas : Sungei Sambas, from 5 min to 2 h upstream, 01 ° 22.76 9 N, 109 ° 20.66 9 E, coll. H. H. Tan, 18 April 1998 ; six males, cl 2.9– 3.8 mm, two ovigerous females, 4.2–4.3 mm, MZB, Sungei Kakap , Kabupaten Kapuas, Kalimantan Barat, 00 ° 04 9 S, 109 ° 11 9 E, coll. D. Wowor, 5 June 1998 ; one male, cl 3.8 mm, one ovigerous female, cl 5.0 mm, ZRC 1995.512 , East Kalimantan: Semunad , Sungei Tulit, tidal influence as far as 300 m downriver ca 4 ° 043.08 9 N, 117 ° 00.04 9 E, coll. M. Kottelat, 12 February 1993 ; Sumatra: four females, cl 2.5–3.9 mm, one ovigerous female, cl 5.5 mm, RMNH, Kluang Bay , South Sumatra, Indonesia, collected from river, freshwater, 10 November 1941 ; seven females, cl 3.5–3.9 mm, ZRC, S. Simpungkii at Sembawang Road , Singapore, coll. 11 July 1961 ; two ovigerous females, cl 5.0– 5.1 mm, ZRC 1979.4.12.146–147, Sungei Seletar at Nee Soon, Singapore, 25 September 1959 ; two males, 4.0– 4.3 mm, six ovigerous females, cl 5.2–5.5 mm, ZRC, Sungei Seletar , station 3, Singapore, coll. P. Yeo Kwai Ho, 23 September 1959 ; one male, cl 2.5 mm, RMNH 11693 , brackish water swamp near Singapore airport, Paya Lebar district , Singapore, pH 6.8, coll. M. Laird, 1 September 1955 ; one ovigerous female, cl 5.5 mm, ZRC, slow, small, tidal stream, draining into Sungei Skudai at mile 7 Johor Bahru, Skudai Road, Malaysia, coll. D. S. Johnson, 10 May 1960 ; two males, cl 1.9–2.0 mm, five females, cl 1.9– 3.5 mm, CU2000.27, Mae Nam Pasuk , Saraburi Province, Thailand, 4 July 1974 ; one male, cl 2.8 mm, one female, cl 3.7 mm, CU 2000.14, Amphoe Photharam , Ratchaburi Province, Thailand, 5 April 1973 ; three males, cl 3.2–3.8 mm, five females, cl 3.0– 3.7 mm, 13 ovigerous females, cl 3.8–4.2 mm, CU 2000.12, Klong Thom , Amphoe Muang, Phang Nga Province, Thailand, 12 May 1974 ; three females, cl 3.0– 6.5 mm, five ovigerous females, cl 3.0– 3.7 mm, CU 2000.12, Klong Thom , Amphoe Muang, Phang Nga Province, Thailand, 12 May 1974 ; one female, cl 2.3 mm, RMNH 21008 , flushing area near Peah , Cambodia, 29 August 1950 ; 67 males, cl 27– 4.1 mm, 32 females, cl 3.4– 5.5 mm, 28 ovigerous females, cl 4.2–5.5 mm, USNM 280305 , Malaga River , Hinunangan Bay, Leyte, Philippines, coll. Albatross Philippine Expedition, 30 July 1909 ; two males, cl 2.5–2.6 mm, three females, cl 2.0– 3.3 mm, one ovigerous female, cl 3.7 mm, ZRC, tributary of Loboc River , Loboc, Bohol, Philippines, coll. Y. Cai, 19 December 2000 ; five males, three females, four ovigerous females, USNM 280319 , Pangauran River at Port Caltom, Busuanga Island, Mindoro Oriental, Philippines, coll. Albatross Philippines expedition, 16 December 1908 ; one female, cl 3.6 mm, USNM 172594 , Ngerbekull River , Babelthuap Island, Palau, coll. G. Right, 1 June 1978 ; one male, cl 3.2 mm, one female, cl 2.4 mm, ZRC, Kangkou Hsi , Manchou village, Pingtung County, Taiwan, coll. Y. Cai et al., 23 November 1997 ; four males, six females, two ovigerous females, ZRC, Veisari River , ca 4 km from W. Lawi, Lawi, Suva, Fiji, coll. A. Auspach, 1 February 1995 ; three males, three ovigerous females, RMNH, Fiji, coll. J. E. Parrot, 1967 ; seven males, one ovigerous female, MNHN Na 724, Tinnevelly, southern India, no date ; one male, six females, three ovigerous females, RMNH D 24205, Lake Marovovo , North of Ambato-Boéni , Pref. Ambato-Boéni, Province Majunge, Madagascar, coll. Y. Therezien, 25 June 1964 .

Comparative material examined

Caridina appendiculata Jalihal and Shenoy, 1998 : lectotype: male, cl 3.1 mm, Caridina gracilirostris De Man, 1892 , syntypes, ZMA De102646, river near Bari, Flores, Indonesia, coll. M. Weber, 1888. Paralectotypes: one male, cl 2.9 mm, three females, cl 2.2–4.3 mm, same data as lectotype. One male, two females, RMNH 30488, Bondokodi River 1–2 km above the bridge near Kodi, 2 August 1949; two males, BMNH 704d, Mentawei, Sulawesi, no date; two males, cl 4.8–4.9 mm, USNM 285309, Baganga River, Mindanao, Philippines, coll. Albatross Philippines Expedition, 13 May 1908; four specimens, USNM 172592, Babelthuap Island, Palau, Metengalakumer River, coll. G. Right, 17 November 1977; seven males, three females, one ovigerous female, MNHN Na722, Waterlot, Madagascar, 1924.

Description

Rostrum ending in bifid tip, reaching far beyond distal end of scaphocerite, 1.5–2.0 times as long as carapace, strongly upturned, armed with three to nine dorsal teeth on posterior half, 28–36 teeth throughout ventral margin; antennal spine short, situated below inferior orbital angle; pterygostomian margin sub-rectangular.

Sixth abdominal somite 0.8 times as long as carapace, 2.0 times as long as fifth somite, as long as telson. Telson very slender, 4.8 times as long as wide, with four pairs of dorsal spinules and one pair of dorsolateral spinules; distal spines very stout, lateral pair distinctly longer than intermediate spines; apparently lacking posteromedian projection. Preanal carina with a spine.

Eyes well developed, anterior end reaching to 0.8 times length of basal segment of antennular peduncle. Antennular peduncle 0.8 times as long as carapace; basal segment longer than sum of second and third segment lengths, anterolateral angle pointed, reaching to 0.4 times length of second segment, second segment distinctly longer than third segment. Stylocerite reaching to 0.8–0.9 times length of basal segment of antennular peduncle. Scaphocerite 4.1 times as long as wide.

Incisor process of mandible ending in a row of small teeth, molar process truncate. Lower lacinia of maxillula broadly rounded, upper lacinia elongate, with distinct teeth on inner margin, palp slender. Upper endites of maxilla subdivided, palp short, scaphognathite tapering posteriorly with some long, curved setae at posterior end. Palp of first maxilliped ending in broad triangular structure. Second maxilliped typical of genus. Third maxilliped reaching to end of second segment of antennular peduncle, with ultimate segment distinctly shorter than penultimate segment.

Epipods on first four pereiopods. First pereiopod not reaching beyond end of eye stalk; merus as long as carpus, 2.5 times as long as wide, carpus 1.7 times as long as high; chela twice as long as broad, finger as long as or slightly longer than palm. Second pereiopod reaching beyond end of basal segment of antennular peduncle, merus shorter than carpus, 3.8 times as long as broad; carpus 1.2 times as long as chela, 4.0 times as long as high; chela 2.2 times as long as broad; fingers 1.4 times as long as palm. Third pereiopod reaching to end of antennular peduncle, with propodus 13 times as long as wide, 4.0 times as long as dactylus; dactylus 3.2 times as long as wide (spines included), with eight spines on flexor margin. Fifth pereiopod reaching to end of basal segment of antennular peduncle, with propodus 12 times as long as wide, 3.8 times as long as dactylus; dactylus 3.7 times as long as wide, with 37 spinules on flexor margin.

Endopod of male first pleopod subtriangular, 0.2 times as long as exopod, without appendix interna. Uropodal diaeresis with 5–11 movable spinules.

Eggs 0.4× 0.25 mm in diameter.

Habitat

Lower parts of streams or rivers with seawater influence, very often from brackish water.

Distribution

Indonesia, Singapore, Malaysia, Thailand, Cambodia, Taiwan, Japan, Palau, Philippines, Fiji, India, and Madagascar.

Remarks

When De Man (1892) described Caridina gracilirostris , he noted that there were two forms of carpus in this species: a short carpus form from Sulawesi and a long carpus form from Flores. Tiwari and Pillai (1971) also reported both forms from different parts of the Andaman Islands.

Jalihal and Shenoy (1998, p 128), in an abstract for a meeting, commented as follows: ‘‘ C. gracilirostris De Man, 1892 . Its syntype material is actually an assemblage of three taxonomic forms, viz., a typical and two atypical forms, the ‘forma typica’ characterized by [the] absence of an appendix interna is actually C. gracilirostris s. s., which is predominantly Indo-Malayan species. Of the two atypical forms, the one possessing a single postorbital tooth and a straight appendix interna and being mainly an African inhabitant with occasional presence in the Malayan archipelago is described as C. n. sp. 1. The other one possessing two postorbital teeth and a curved appendix interna and apparently endemic to Flores is described as C. appendiculata n. subsp. 2.’’ No lectotype of C. gracilirostris was formally stated or designated. However, we have discovered that some Madagascan specimens, in RMNH, had been labelled by Jalihal and Shenoy as the types of ‘‘ C. appendiculata ’’, although this information was not published.

Re-examination of the syntypes of C. gracilirostris shows that there are indeed three species. One, the typical form, from Maros and Bapanguipa, Sulawesi, has no appendix interna on the endopod of the male first pleopod; the rostrum has fewer than 10 teeth, there are no postorbital teeth; the telson does not terminate in a posteromedian projection; and the carpus of the first pereiopod is short, less than twice as long as high. A second form, from Bari, Flores, has an endopod on the male first pleopod which possesses a distinct appendix interna, the dorsal margin of the rostrum is armed with more than 10 teeth, of which one or two are situated behind the postorbital margin; the telson terminates in a posteromedian projection; and the carpus of first pereiopod is slender, 2.0–2.5 times as long as high. The third form, from Reo, Flores, has an endopod of male first pleopod which possesses a distinct appendix interna; the rostrum has fewer than 10 teeth, without any postorbital teeth; the telson does not terminate in a posteromedian projection; and the carpus of the first pereiopod is slender, being 2.3–2.9 times as long as high. These three forms are all superficially similar in the form of the rostrum, but can be differentiated from each other easily by the combination of rostral formula and structure of sexual appendages. To stabilize the taxonomic status of these species, we here designate a male specimen from Maros, Sulawesi, as the lectotype of C. gracilirostris . As Jalihal and Shenoy (1998) clearly mentioned the main characters of C. appendiculata in their abstract, their action makes the name available although they did not mention the types even though we know that they had in fact labelled a holotype and paratypes from a series of Madagascan specimens in the RMNH. However, Jalihal and Shenoy’s (1998) abstract did not list the type material, although they did state that C. appendiculata was described for the population ‘‘apparently endemic to Flores’’ ( Jalihal and Shenoy, 1998, p 128) and they referred to De Man’s (1892) specimens. This action alone makes De Man’s (1892) material from near Bari, Flores, which is now in RMNH, syntypes. Their labelling of the RMNH specimens from Madagascar as the types of C. appendiculata therefore seems odd. This action was probably done after they had decided the species was new and realized later that the material in RMNH from Madagascar was also C. appendiculata , and the species was not just found on Flores. We therefore here designate one of the syntypes of C. gracilirostris (male, cl 3.1 mm, ZMA De 102646), which was from Rive Bari, Flores, as the lectotype of C. appendiculata Jalihal and Shenoy, 1998 . Caridina appendiculata is moved to the C. nilotica species group due to the presence of postorbital teeth on the rostrum, a diagnostic character of this group (Y. Cai and P. K. L. Ng, in preparation). The third species, although noted as different by De Man as early as a century ago, remains undescribed, for which the name Caridina neglecta is here proposed.

Caridina pseudogracilirostris Thomas, Pillai, and Pillai, 1976 , from Cochin backwater, India, is clearly identical to C. gracilirostris s. str. as the description and the drawings demonstrated, especially in the absence of the appendix interna in the endopod of the male first pleopod. Richard and Chandran (1994) had synonymized C. pseudogracilirostris with C. gracilirostris , although they did not realize that there are actually three species involved in the type series of C. gracilirostris .

Holthuis (1965) reported C. gracilirostris from Madagascar. His drawing actually shows C. appendiculata . However, a re-examination of his material shows that one of his lots from Waterolt in Madagascar is indeed C. gracilirostris , the rest being C. appendiculata . Holthuis (1978) also reported C. gracilirostris from Sumba, Lesser Sunda Islands. Re-examination of part of his specimens shows that there are two species involved, C. gracilirostris and C. appendiculata , both from Bondokadi River, West Sumba.

Without detailed descriptions and/or figures of the teeth arrangement, proportions of the various segments of the pereiopods and structure of male first pleopod, the actual identity of many previous records of ‘‘ C. gracilirostris ’’ by various authors cannot be determined for the time being.

Caridina gracilima Lanchester, 1901

( Figure 3 )

Caridina gracilima Lanchester 1901, p 560 , Plate 34, Figure 1 [type locality: inner lake of Tale Sap , Southern Thailand].

Caridina gracilima: Bouvier 1905, p 72 , Plate 39; 1913, p 463; 1925, Plate 40, Figures 301– 304; Kemp 1918, p 285.

Caridina gracilirostris: Johnson 1961, p 124 (part).

Not Caridina gracilima: Blanco 1935, p 32 , Figures 5 –10.

Material examined

Lectotype (here designated): ovigerous female, cl 4.2 mm, eggs 0.58× 0.42 mm, MNHN Na741, Malay Peninsula, 1899 . Paralectotypes: one male, cl 3.9 mm, one male, cl 2.6 mm, same data as lectotype ; one male, cl 2.8 mm, one female, cl 4.0 mm, MNHN Na 740, Malay Peninsula , exchanged from the Museum of the University of Cambridge , 1912. One female, cl 3.4 mm, one ovigerous female, cl 4.0 mm, eggs 0.66× 0.40 mm, MNHN Na 739, among weeds at mouth of Lampam River, Tale Sap, Singgora, Thailand, coll. N. Annandale, 1899 .

Other material. Two females, cl 3.8–4.5 mm, one ovigerous female, cl 4.0 mm, eggs 0.6× 0.4 mm, ZRC, Mae Sot Market, Thailand, coll. H. H. Tan and H. H. Ng, 27 May 1999; one female, cl 3.1 mm, one ovigerous female, cl 3.3 mm, CU2000.29, Amphoe Muak Lek Waterfall , Saraburi Province, Thailand, 23 December 1974 ; two ovigerous females, cl 4.2–4.5 mm, USNM 65554 , Bangkok, Thailand, coll. H. M. Smith, 4 August 1925 ; one male, cl 3.1 mm, one ovigerous female, cl 3.8 mm, eggs 0.6× 0.4 mm, one ovigerous female, cl 3.9 mm, CU2000.04, Rayong Province, Thailand, 8 December 1973 ; one female, cl 4.5 mm, two ovigerous females, cl 4.3–4.6 mm, CU 2000.16, Ratchaburi Province, Thailand, 6 November 1973 ; one male, cl 2.8 mm, two ovigerous females, cl 3.7– 3.8 mm, ZRC, Rayang , Thailand ; six females, cl 3.8–4.2 mm, six ovigerous females, cl 3.5– 4.0 mm, eggs 0.6× 0.4 mm, CU2000.13, Ratchaburi Province, Thailand, 18 November 1973 .

Description

Rostrum ending in bifid tip, reaching far beyond distal end of scaphocerite, slightly longer than carapace to 1.6 times as long as carapace, strongly upturned, armed with 5–10 dorsal teeth on posterior half, with 19–24 teeth along whole ventral margin; antennal spine short, situated lower than inferior orbital angle; pterygostomian margin broadly rounded.

Sixth abdominal somite 0.8 times as long as carapace, 1.9 times as long as fifth somite, slightly longer than telson. Telson 3.7 times as long as wide, with four pairs of dorsal spinules and one pair of dorsolateral spinules; distal spines short, stout, lateral pair slightly longer than intermediate spines; lacking posteromedian projection. Preanal carina without spines.

Eyes well developed, anterior end reaching to 0.9 times length of basal segment of antennular peduncle. Antennular peduncle 0.8 times as long as carapace; basal segment of antennular peduncle longer than sum of second and third segment lengths; second segment distinctly longer than third segment. Stylocerite reaching to 0.8 times length of basal segment of antennular peduncle. Scaphocerite very slender, 4.0 times as long as wide.

Mouthparts similar to Caridina neglecta . Palp of first maxilliped ending in a finger-like projection. Second maxilliped typical of genus. Third maxilliped reaching near end of antennular peduncle, with ultimate segment distinctly shorter than penultimate segment.

Epipods on first four pereiopods. First pereiopod not reaching to end of eye stalk; merus 2.4 times as long as broad; carpus slightly longer than merus, 1.6 times as long as high; chela 2.2 times as long as broad, fingers as long as palm. Second pereiopod reaching to end of basal segment of antennular peduncle, merus shorter than carpus, 4.2 times as long as broad; carpus as long as chela, 4.2 times as long as high; chela 3.1 times as long as broad; fingers 1.2 times as long as palm. Third pereiopod reaching to end of antennular peduncle, with propodus 12 times as long as wide, 4.0 times as long as dactylus; dactylus 3.5 times as long as wide (spines included) with six to nine spines on flexor margin. Fifth pereiopod reaching to end of second segment of antennular peduncle, with propodus 14 times as long as wide, 3.2 times as long as dactylus; dactylus 4.0 times as long as wide, with 30–47 spinules on flexor margin.

Endopod of male first pleopod subtriangular, 0.2 times as long as exopod, without appendix interna.

Uropodal diaeresis with 6–10 movable spinules.

Eggs 0.55–0.66× 0.35–0.40 mm.

Habitat

A variety of lowland freshwater habitats.

Remarks

With regard to the short carpus of the first pereiopod, and the absence of an appendix interna on the endopod of male pleopod, Caridina gracilima resembles C. gracilirostris . Kemp (1918) differentiated C. gracilima from C. gracilirostris in detail, i.e. in its shorter rostrum; presence of fewer ventral rostral teeth; fewer spinules on the diaeresis of the uropod; relatively larger eggs (0.65–0.70 versus 0.33–0.52 mm) and smaller body size. Based on a larger collection from various localities in Thailand, we find that all these are good characters. Some specimens of C. gracilima , however, have quite a long rostrum, and the ventral rostral teeth also could be as many as 24. Other than the characters mentioned by Kemp, there is one more important character, the absence of a preanal spine, which was mentioned by Bouvier (1925). This character can be effectively used to separate C. gracilima from C. gracilirostris .

Woltereck (1937) reviewed the distribution of the genus Caridina and mentioned the variability of the carpus of the first pereiopod in C. gracilirostris , and considered C. gracilima to be indistinguishable from C. gracilirostris . Johnson (1961) followed Woltereck’s suggestion, provided a more detailed discussion and treated C. gracilima as a junior synonym of C. gracilirostris . The fact that both authors had not examined any specimens of C. gracilima , and were unaware of the taxonomic confusion within the C. gracilirostris species complex, probably misled them.

The only record for the species outside Thailand was that of Blanco (1935) from the Philippines. According to his description and illustration, his specimens are definitely not C. gracilima . They are most probably C. gracilipes De Man, 1892 , instead.

We have examined a series of syntypes of C. gracilima Lanchester, 1901 , in MNHN. The best female specimen is here selected as the lectotype of the species.

Distribution

Known with certainty only from Thailand.

Figures

Figure 1. Caridina gracilirostris. (A) Cephalothorax and cephalic appendages; (B) telson; (C) distal portion of telson; (D) scaphocerite; (E) mandible; (F) maxillula; (G) maxilla; (H) first maxilliped; (I) second maxilliped; (J) third maxilliped; (K) endopod of male first pleopod; (L) appendix masculina and appendix interna of male second pleopod. (A, K, L) Syntype, male, 3.5 mm, ZMA DE 102645; (B–J) female, cl 5.2 mm, USNM 280305, Malaga River, Hinunangan Bay, Leyte, Philippines. Scale bars: 1 mm (A); 0.5 mm (B, D–J); 0.1 mm (C); 0.2 mm (K, L).

Figure 2. Caridina gracilirostris. (A) Cephalothorax and cephalic appendages; (B) first pereiopod; (C) second pereiopod; (D) third pereiopod; (E) dactylus of third pereiopod; (F) fifth pereiopod; (G) dactylus of fifth pereiopod; (H) endopod of male first pleopod; (I) appendix masculina and appendix interna of male second pleopod; (J) preanal carina; (K) diaeresis. (A–G, J) Female, cl 5.2 mm; (H, I) male, cl 5.2 mm, USNM 280305, Malaga River, Hinunangan Bay, Leyte, Philippines. Scale bars: 1 mm (A); 0.5 mm (B–D, F, J); 0.2 mm (E, I); 0.1 mm (G, H, K).

Figure 3. Caridina gracilima. (A) Cephalothorax and cephalic appendages; (B) telson; (C) distal portion of telson; (D) scaphocerite; (E) first pereiopod; (F) second pereiopod; (G) third pereiopod; (H) dactylus of third pereiopod; (I) fifth pereiopod; (J) dactylus of fifth pereiopod; (K) preanal carina; (L) diaeresis. Male, cl 4.5 mm, USNM 65554, Bangkok, Thailand. Scale bars: 1 mm (A); 0.5 mm (B, D–G, I, K); 0.1 mm (C, H, J, L).

Figure 5. Caridina neglecta, new species. (A) Cephalothorax and cephalic appendages; (B) telson; (C) distal portion of telson; (D) first pereiopod; (E) second pereiopod; (F) third pereiopod; (G) fifth pereiopod; (H) preanal carina; (I) diaeresis. Male, cl 5.3 mm, USUM 285309, Baganga River, Mindanao, Philippines. Scale bars: 1 mm (A), 0.5 mm (B, D–G), 0.2 mm (C, I).