Caridina propinqua De Man, 1908

Cai, Y., 2006, Atyid shrimps (Crustacea: Decapoda: Caridea) of the Ryukyu Islands, southern Japan, with descriptions of two new species, Journal of Natural History 40 (38 - 40), pp. 2123-2172 : 2150-2154

Caridina propinqua De Man, 1908

( Figures 10 and 11 )

Caridina propinqua De Man, 1908b, p 227 , pl 19, fig. 6 [type locality: Dhappa , near Calcutta, India].

Caridina propinqua: Kemp 1915, p 309 ; 1918, p 274; Bouvier 1925, p 181, figs. 375, 381; Johnson 1961, p131, figs. 12–15; De Silva 1982, p 127, fig. 5; Ng and Choy 1990, p 17; Shokita 2003, p 250, fig. 18D; Shokita 2005c, p 216; 2006f, p 61; Shokita et al. 2002a, p 88; Shokita et al. 2003a, p 101.

Caridina blancoi Chace 1997, p 7 , fig. 2 [type locality: Tayabus River , Luzon Island Philippines].

Caridina hainanensis Liang and Yan, 1983, p 211 , fig. 1 [Wenchang County, Hainan Island, China].

Caridina hainanensis: Liang 2004, p 302 , fig. 148.

Material examined

One male, cl 2.9 mm (USNM-264045, holotype of Caridina blancoi ), near mouth of Tayabas River, Luzon Island, Philippines, 25 February 1909; 1 male, cl 2.2 mm (SHU-79-310-1, holotype of Caridina hainanensis ), 1 female, cl 4.0 mm (SHU-79-310-2, paratype of C. hainanensis ), Wenchang County, Hainan Island , China, coll. X. Liang and S. Yan, 14 April 1979 ; 11 males, cl 2.6–3.3 mm, 6 females, cl 3.5–3.8 mm, 16 ovigerous females, cl 3.4–4.0 mm, URB, mangrove of Nakama River , Iriomote Island, Ryukyu Islands, coll. S. Shokita, 3–5 June 1985 ; 30 specimens, ZRC 2004.0579 , tide-pool in mouth of Shira River , Iriomote Island, Ryukyu Islands, 5 October 1982 .

Diagnosis

Rostrum ( Figure 10A, G ) straight or sloping ventrally anteriorly, reaching near middle of second segment of antennular peduncle, to end of third segment. Rostral formula: 3–4+9–16/ 1–7/1–6(3–4), no apical teeth. Suborbital angle acute, distinctly separated from antennal spines; pterygostomian margin rounded. Preanal carina ( Figure 10B ) with a spine. Telson ( Figure 10C, D ) with three to four pairs of dorsal spines and small posteromedial projection, lateral pair of spines longer than intermedial pairs. Antennular peduncle long, subequal to carapace length. Stylocerite reaching 0.8 times length of basal segment of antennular peduncle. Scaphocerite ( Figure 10F ) 4.0 times as long as wide. First pereiopod ( Figure 11A ) with carpus 2.3 times as long as high, chela 2.5 times as long as broad, finger longer than palm. Second pereiopod ( Figure 11B ) with carpus 6.8 times as long as high, chela 4.1 times as long as broad, fingers 2.0 times as long as palm. Third pereiopod ( Figure 11C, D ) with propodus 3.2 times as long dactylus, propodus without enlargement. Dactylus ending in two claws, with one to four spines on flexor margin. Fifth pereiopod ( Figure 11E, F ) with propodus 2.5 times as long as dactylus; dactylus ending in one claw, with 57–76 spinules on flexor margin. Endopod of male first pleopod with no appendix interna. Uropodal diaeresis with 13–19 spinules. Egg size: 0.38–0.48× 0.25–0.30 mm.

Habitat

Lower reaches of rivers or mountain streams which discharge to the sea. Commonly found in mangrove creeks.

Remarks

Liang and Yan (1983) described Caridina hainanensis on the basis of specimens from Hainan Island. Their species has the same typical characteristics as C. propinqua , namely the form of the rostrum and the telson, the form of various pereiopods, especially the third, which has a very small number of spines (one to three in C. hainanensis vs. one to four in C. propinqua ) on the flexor margin of the dactylus, the identical form of the endopod of male first pleopod. Re-examination of the types indicated that C. hainanensis should be regarded as a junior synonym of C. propinqua .

Chace (1997) proposed a new species, based on a single specimen. He commented that ‘‘(t)he proposal of a new species, based on a single specimen in a genus that is noteworthy for its variable species, may be questionable, but it seems desirable to call attention to a taxon that apparently differs from all others known in a combination of characters; the form and dentition of the rostrum and telson; the prominence of the suborbital angle; and the form of the chelae and carpi of two anterior pereiopods and of the dactyls of the third and fourth pereiopods.’’ Re-examination of the holotype confirms that it is identical with C. propinqua .

Egg size of this species is quite variable. It is 0.39–0.45× 0.24–0.27 mm in specimens from Hainan ( Liang and Yan 1983), 0.54× 0.36 mm in populations from Malaysia ( Johnson 1961) and 0.38–0.48× 0.25–0.30 mm in the present specimens from the Ryukyus. Kemp (1918) reported C. propinqua from southern Thailand. The identity of his species is doubtful as it had an egg size of 0.64–0.70× 0.39–0.44 mm, which is much larger than in specimens from elsewhere.

This record has recently been reported by Shokita (2003). Previously, Caridina propinqua has been reported from Sri Lanka ( De Silva 1982), India ( De Man 1908b; Kemp 1915), Malaysia ( Johnson 1961; Ng and Choy 1990), southern China ( Liang and Yan 1983) and the Philippines ( Chace 1997).

Distribution

Sri Lanka, India, Malay Peninsula, Philippines, and China.

Figures

Figure 10. Caridina propinqua. A, cephalothorax and cephalic appendages, lateral view; B, preanal carina; C, telson; D, distal portion of telson; E, diaeresis; F, scaphoceite; G, cephalothorax and cephalic appendages, lateral view; H, male first pleopodc; I, male second pleopod. Scales: A–C, F, G51 mm; D, E, H, I50.2 mm (A–F, female, cl 4.0 mm, URB; G–I, male, cl 2.8 mm, URB).

Figure 11. Caridina propinqua. A, first pereiopod; B, second pereiopod; C, third pereiopod; D, dactylus of third pereiopod; E, fifth pereiopod; F, dactylus of fifth pereiopod. Scales: A–C, E50.5 mm; D, F50.2 mm (female, cl 4.0 mm, URB).