Caridina simoni Bouvier, 1904

Richard, Jasmine & Clark, Paul F., 2014, Caridina simoni Bouvier, 1904 (Crustacea: Decapoda: Caridea: Atyoidea: Atyidae) and the synonymy by Johnson, 1963, Zootaxa 3841 (3), pp. 301-338 : 303-308

Caridina simoni Bouvier, 1904

( Figs. 1 , 2 )

Caridina simoni Bouvier, 1904: 131 ; 1905: 73, 80, fig. 4; 1912: 918.

Caridina aruensis J. Roux, 1911: 82 ; Bouvier, 1913a: 463; 1913b: 181.

Caridina nilotica var. simoni Bouvier, 1925: 157 , figs. 327–331.

Caridina nilotica simoni Arudprakasam & Costa, 1962: 19 ; Costa, 1972: 130.

Caridina nilotica var. aruensis J. Roux, 1920: 321 ; 1926b: 248; Bouvier, 1925: 156; Reik, 1953: 118, fig. 7.

Caridina simoni simoni de Silva 1983: 205 , 208, 209.

Caridina kunnathurensis Richard & Chandran, 1994: 250 , fig. 4; Mariappan & Richard, 2006: 30, figs. 15–17; Ragunathan & Valarmathi 2007: 95.

Material examined. Types: Syntypes. Sri Lanka ( Ceylon). coll. E. Simon, 1904, MNHN Na 856 2♂, 1♂ selected as a lectotype now MNHN-IU-2013-11816, 1♂ as a paralectotype now MNHN-IU-2008-14721; Cotype, coll. E. Simon, 1904, exch. Paris Museum, 117-97, NHM reg. 1907.1.7.33, 1♀, selected as a paralectotype.

Non types: Sri Lanka. irrigation streams, Peradeniya, pres. R. Gurney, NHM reg.1920.2.5.11–13, 4♀; stream running in to Mahawallagunga River, Peradeniya, pres. R. Gurney, NHM reg. 1920.2.5.14–16, 1♂, 1♀ ovig., 1♀, 1 damaged specimen; Keani River, Kekirawa, Colombo, pres. D.R.R. Burt, NHM reg. 1935.5.30.26–27, 4♂, 3♀; Kalaweva, April 1932, pres. D.R.R. Burt, Department of Zoology, University College, NHM reg. 1935.5.30.15–19, 1♂ (abnormal), 4♀ ovig., 2♀; from streams running into Mahawallaganja, pres. Dr. R. Gurney, det. W.T. Calman NHM reg. 1947.3.18, 1♀ ovig; pres. Dr. R. Gurney, NHM reg. 1950.1.2.148, dissected parts; irrigation streams, Peradeniya, pres. Dr. R. Gurney, NHM reg. 1951.2. 17.1792/3, 1♂, 1♀; fresh water pond, Botanical Gardens, Perademiya, 17.6.1954, coll. & pres. E.S. Brown, NHM reg. 1954.10.27.1–10, 20♂, 5♀ ovig., 7♀; Ambanganga Anoiont, nr. Polonarraw, 1962, coll. & pres. C.H. Fernandes, NHM reg. 1962.8.24.104, 3♀ ovig., 1♀. India. Hindupur, S. India. coll. P.K. Sartory, pres. Mr. Scourfield, det. J. Richard & P. Cark 2009, NHM reg. 1945.vii.27.5–12, 3♂, 4♀; Madras (Chennai) area, coll. and pres. Dr. Sanjeevaraj, det. I. Gordon, 0 5. 1965. NHM reg. 1965.5.7.1–10, 31♀ ovig.

Other material: Caridina aruensis . Types: Syntype. Indonesia. Ruisseau Matora, Soungi Manoumbai, Isle Arou, coll. H. Merton, 15.3.1908, Papouse Muse de Bale, 1913, MNHN reg. Na 664, 1♂; Cotypes. Ruisseau Matora, Soungi Manoumbai, Isle Arou, coll. H. Merton 15.3.1908, Papouse Muse de Bale, 1913, MNHN reg. Na 665, 2♂, 1♀ ovig.

Caridina kunnathurensis . Paratype. India. Kunnathur, 25 kilometers from Madras (now Chennai), Tamilnadu state, 1982, coll. & pres. J. Richard, RMNH reg. D 35564, 1♂, 4♀ ovig.

Description. Adult size 18–32 mm. Carapace length 3.5–4.0 mm.

Rostrum ( Fig. 1 a–c): Slender, 1.0–1.2×long as carapace, reaching antennal scale or slightly longer. Dorsal margin with 15–25 proximal teeth leaving distally 0.25–0.4 unarmed or interrupted by 1–4 teeth. 3–5 post orbital teeth present. Tip pointed. Ventral margin with 5–14 teeth proximally leaving the distal margin unarmed. However, 1♀ from Kalaweva, Sri Lanka possessed 19 teeth on the ventral margin which is considered to be an exceptional occurrence. Formula (3–5) 15–25+0–4/5–14.

Antennular peduncle ( Fig. 1 a–c): 0.6–0.9×carapace. Stylocerite 0.6–0.7×length of basal segment. Anterolateral teeth of basal segment 0.19–0.25×second segment. 15–25 segments bearing aesthetascs.

First pereiopod ( Fig. 2 a): Dactylus 1.1–1.3×palm of propodus. Chela 1.7–2.3×long as broad. Carpus 1.8–2.3×long as broad, anterior excavation shallow.

Second pereiopod ( Fig. 2 b): Long and slender. Dactylus 1.2–2.0×long as palm of propodus. Chela 2.3–2.9×long as broad. Carpus 4.5–5.5×long as broad.

Third pereiopod ( Fig. 2 c, d): Dactylus 2.0–3.0×long as broad. 6–9 spines on dactylus (including terminal spines), mostly 6–7. Propodus 5.0–5.6×long as dactylus and 9–12×long as broad with 10–14 spines along inner margin. Carpus 0.45–0.6×long as propodus, with 1 large spine and 3–5minute spines on inner margin. Merus 1.6–2.0×carpus length. Merus with 4 large spines on posterior margin. Ischium with a spine

Fifth pereiopod ( Fig. 2 e, f): Dactylus 3.9–5.0×long as broad with 35–60 spines in comb-like fashion on inner margin. Propodus 10–14×long as broad and 3.2–3.9×long as dactylus and with 10–15 spines along posterior margin. Carpus 0.45–0.7×propodus length and with minute spines along inner margin. Merus 1.5–2.0×carpus length, with 3 large spines at posterior margin. Ischium with a spine.

Setobranchs: 2 setae on all pereiopods.

First male pleopod ( Fig. 2 g–i): Endopod 0.25–0.35×exopod length and usually possess a distinct appendix interna, but in 1♂ from Hindupur appendix interna absent. Several long setae present along the entire margin.

First female pleopod ( Fig. 2 j): Ratio of the endopod to exopod length varies remarkably from 0.35–0.8.

Eggs ( Fig. 2 k): 50– 160 eggs of 0.65–1.0× 0.45–0.6 mm size.

Second male pleopod ( Fig. 2 l, m): Appendix masculina 1.4–1.7×appendix interna and 0.3–0.4×endopod.

6th abdominal somite: 0.57–0.86×long as carapace.

Telson ( Fig. 2 n, o, p): Broad, 1–1.15×long as 6th abdominal somite. Dorsal spines 4–6 pairs (including subterminal spine). Posterior margin broad and rounded, mostly without a median process, bearing 1 pair of long lateral spines and 3–4 pairs sparsely plumose spines that are of equal length and shorter than laterals or central pair fractionally longer and of equal length to lateral spines.

Uropod ( Fig. 2 q): 8–14 diaeresis spinules.

Preanal carina ( Fig. 2 r): Unarmed.

Distribution. Sri Lanka; India; Aru Islands, Indonesia and Australia.

Type locality. Ceylon ( Sri Lanka).

Remarks. Bouvier (1904) initially provided a brief description of C. simoni stating that the species lacked a subapical tooth, possessed a long rostrum reaching beyond the antennular peduncle and dorsal and ventral rostral margins were unarmed distally. He considered that his new species was near to C. wycki var. gracilipes De Man, 1892 and C. ensifera Schenkel, 1902 . Later, Bouvier (1905) described C. simoni in more detail and included an illustration of the anterior region of the cephalothorax as well as the first, second and fifth pereiopods. He highlighted a number of diagnostic characters for C. simoni including the rostrum being longer than the antennular peduncle, absence of subapical teeth and distally ⅓ of the dorsal margin and ¼ of the ventral margin being unarmed. Bouvier (1905) also noted the dental formula in a key, 2+16–4+18/8–11. However, during his study of C. nilotica ( P. Roux, 1833) and its varieties, Bouvier (1925) referred to C. n. simoni . He provided illustrations of the first male pleopod with the appendix interna, carpus and epipod of the first pereiopod, and the posterior margin of the telson. Throughout his studies, Bouvier (1904, 1905, 1925) confirmed that the tip of the rostrum in C. n. simoni was always pointed, a character later noted by Arudprakasam & Costa (1962) and confirmed by Costa (1972). In fact, Arudprakasam & Costa (1962) distinguished their new subspecies of C. n. zeylonica from C. n. simoni mainly on the basis of the morphology of the rostrum. They also considered the absence of a sub-apical tooth in C. n. simoni as an important distinguishing feature.

Johnson (1963) based his studies mainly on miscellaneous observations of specimens from European museums. He described C. simoni as, “a rather stout species which is distinctly more heavily built than specimens of true C. nilotica which I have seen, though the distinction is both difficult to describe and to figure”. This statement is superficial and appears not to be based on any diagnostic characters. Furthermore, Johnson (1963) synonymised several distinct species (see Table 1 ) that he considered junior synonyms of C. simoni . Therefore Johnson’s concept of C. simoni is questionable and his reference to this species is not included in the above synonymy. Truly the synonymy of Johnson (1963) was responsible for the difficulties in identifying C. simoni and several other distinct species.

de Silva (1982) described a new species of Caridina from Sri Lanka namely Caridina costai and considered it to be closer to C. simoni . He distinguished C. costai by its broad shorter rostrum that just reaches the antennular peduncle or is shorter (vs. a slender rostrum that reaches beyond the antennular peduncle in C. simoni ). de Silva (1982) also provided several other measurements that appear to fall within the range of C. simoni . The examination of more C. simoni samples by the present study confirms that the slender rostrum of C. simoni is slightly longer than the antennal scale but not shorter than the antennular peduncle and in addition, there are more teeth on the ventral margin of the rostrum in C. simoni 5–14 (vs. 5–8 in C. costai ).

Benzie & de Silva (1984) who tried to prevent “nomenclatural confusion”, rejected the decision by Johnson (1963) of affording species status to C. n. simoni because they considered that he provided no numerical data. Also, they ( Benzie & de Silva 1984) considered C. n. zeylonica of Arudprakasam & Costa (1962) and C. costai of de Silva (1982) as population variants of C. n. simoni . Further, Benzie & de Silva (1984) decided that rostral shape and spinulation are highly unreliable taxonomical characters in Atyidae . With reference to Johnson (1963), Benzie & de Silva (1984) emphasised the need for numerical data and reliable characters when making taxonomic decisions. Their identification of C. costai , C. n. simoni and C. n. zeylonica was based on three characters, the proportion of the 6th abdominal segment to carapace, dactylus to propodus length of the 5th pereiopod and the spinules on the dactylus of the fifth pereiopod. The measurements as presented by them ( Benzie & de Silva, 1984) are overlapping for the three species. Their total rejection of rostral morphology as a taxonomic character for Caridina with reference to Smith & Williams (1980) could lead to misidentification. Caridina requires a combination of several taxonomic characters for valid identification. The morphology, number of teeth and their placement on the rostrum are important identification characters.

Based on the examination of type and non-type specimens from Sri Lanka and India, the present study considers C. simoni to be a valid and distinct species. The following features are characteristic of the species: rostrum long and slender, reaching antennal scale or slightly longer, tip of the rostrum always pointed, 15–25 teeth proximally on the dorsal margin leaving 0.25–0.4 distally unarmed or interrupted by 1–4 teeth, 3–5 post orbital teeth present, 5–14 teeth proximally on the ventral margin leaving distal end unarmed, rostral formula (3–5) 15–25+0–4/5–14; carpus of the first pereiopod 1.8–2.3×long as broad, anterior excavation shallow, 6–9 spines on dactylus of third pereiopod, propodus 3.2–3.9×long as dactylus, 30–60 spines on dactylus of fifth pereiopod; posterior margin of telson rounded mostly without a median process, bearing 1 pair of long lateral spines and 3–4 pairs of sparsely plumose spines that are either equal in length and shorter than the lateral spines or the central pair of equal length to the lateral spines; 8–14 uropod diaeresis spinules present; ca. 50– 160 eggs of 0.65–1.0× 0.45–0.6 mm in size; endopod of the first male pleopod usually with an appendix interna, rarely without.

The type specimens of C. aruensis J. Roux, 1911 were examined and the following characters are confirmed: Adult size 20–25 mm; rostrum equal to or slightly longer than the antennal scale, tip pointed, formula (3–4) 20–25/ 7–9 with 0.25–0.4 of the dorsal margin unarmed distally or interrupted by 1–3 teeth, ventral margin with a short unarmed end distally, posterior margin of the telson rounded with a pair of long lateral spines and 2 pairs or 3 intermediate spines of equal length; 6–14 uropod diaeresis spinules; endopod of the male first pleopod with appendix interna and preanal carina unarmed. It was noted that the number of intermediate spines on the posterior margin of telson is lesser when compared to C. simoni (3–4 pairs). Based on these observations, the present study confirms the decision of Johnson (1963) and considers C. aruensis to be a junior synonym of C. simoni . From the description of C. n. aruensis by J. Roux (1920, 1926b), it is accepted that C. simoni is distributed in Indonesia and Australia. In addition, the paratypes of C. kunnathurensis Richard & Chandran, 1994 from Kunnathur near Madras were re-examined and this species is considered to be a junior synonym of C. simoni . In addition, the present study examined more specimens from Hindupur, Andhra Pradesh, and Madras, India, and confirms that the distribution of C. simoni is extended to India. Furthermore, after examining a series of type and non-type specimens the present study considered that the many species that Johnson (1963, Table 1 ) listed as junior synonyms of C. simoni , are in fact valid species and the following nomenclatural changes are required.

Figures

FIGURE 1. Caridina simoni Bouvier, 1904, NHM 1945. vii. 27.5 – 12, ♂: a) Entire; b) Anterior region of the cephalothorax. NHM 1907.1. 7.33, Cotype now Paralectotype ♀: c) Anterior region of the cephalothorax.

FIGURE 2. Caridina simoni Bouvier, 1904, NHM 1945. vii. 27.5 – 12, ♂: a) First pereiopod; b) Second pereiopod; c) Third pereiopod; d) Dactylus of the third pereiopod; e) Fifth pereiopod; f) Dactylus of fifth pereiopod; g) First male pleopod; h) endopod of first male pleopod; ♂: i) Endopod of first male pleopod; NHM 1935.5.30.15 – 19, ♀ ovig.: j) First female pleopod; k) Egg. NHM 1945. vii. 27.5 – 12, ♂: l) Second male pleopod; m) Appendix masculina; n) Telson; o) Posterior margin of telson; NHM 1907.1. 7.33, Cotype now Paralectotype, ♀: p) Posterior margin of telson; NHM 1945. vii. 27.5 – 12, ♂: q) Uropod diaeresis spinules; r) Preanal carina.