Conchodytes nipponensis (De Haan, 1844)

Lee, Seok Hyun & Ko, Hyun Sook, 2013, The first record of Conchodytes nipponensis (De Haan, 1844) (Crustacea: Decapoda: Palaemonidae) associated with pen shell Atrina pectinata (Linnaeus, 1767) (Mollusca: Bivalvia) from Korea, Journal of Species Research 2 (1), pp. 1-6 : 1-5

2 * Conchodytes nipponensis (De Haan, 1844) ( Figs. 1-3 )

Hymenocera nipponensis De Haan, 1844 , pl. 46, fig. 8.

Korean name: 1 * ḤŀfflNjșẁ, 2 * ḤŀfflNjș

Pontonia nipponensis : De Haan, 1849, p. 180.

Conchodytes nipponensis : Kemp, 1922, pp. 260, 279; Kubo, 1940, pp. 58 (key), 64-67, figs. 28-29; Suzuki, 1971, pp. 94-96, fig. 2, pl. 1; Bruce, 1977, pp. 97-100, fig. 1; Miyake, 1982, p. 36, fig. 13; Chace and Bruce, 1993, pp. 75, 76, fig. 19; Fransen, 1994, pp. 91-96, figs. 8, 9, 16-18, 24, 28, 32, 33, 36.

Material examined. 1@ (cl 8 mm), 3¥¥¥ (cl 9, 9, 8 mm), Yeongdo (Busan), 30 Jun., 2010, Lee SH, SCUBA in 15 m depth (35.03.37N 129.04.34E).

Diagnosis. Body glabrous, slightly depressed. Rostrum ( Fig. 2A, B ) slightly curved ventrally, with bluntly rounded tip, slightly overreaching medial margin of second segment of antennular peduncle. Carapace ( Fig. 2A, B ) slightly depressed, produced posteriorly; supraorbital, hepatic, and antennular spines absent; inferior orbital angle produced. Abdomen ( Fig. 2A, B ) each somite with rounded pleuron; first to third somites large; fourth one smaller; fifth one smallest. Telson ( Fig. 2A, C ) with 3 pairs of dorsolateral and 2 pairs of posterior spines. Eye ( Figs. 1 , 2A, B ) moderately short, stout, and globular; eyestalk subcylindrical; corneal diameter smaller than eyestalk width. Antennular peduncle ( Fig. 2D ) with 1 ventromedial spine on basal segment. Scaphocerite ( Fig. 2E ) with lamella approximately 1.6 times longer than central width, lateral margin strongly convex, with sharp distolateral tooth. Third maxilliped ( Fig. 3A ) slender, with long setae on inner margin; ischium subrectacular, about 2.8 times longer than broad; exopod with long setae distally. First pereopod ( Fig. 3B, B′ ) long, slender, subcylindrical; fingers tapering, slightly longer than palm, with setae laterally, without teeth. Second pereopod ( Fig. 3C, D ) subequal, robust; palm subcylindrical, slightly swollen, approximately 3 times as long as width; fingers short, distally hooked, with 2 teeth on each cutting margin. Third to fifth pereopods ( Fig. 3 E-G) short, slender, slightly depressed; each merus, carpus and propodus unarmed; each dactyl compressed, biunguiculate with rounded proximoventral and bearing with pointed tip.

Color of in life. Generally pinkish red with white spots.

Habitat. Conchodytes nipponensis can be found in the mantle cavity of Amusium balloti (Bernardi, 1861) , Atrina japonica (Reeve, 1858) , and Pecten albicans (Schröter, 1802) (see Bruce, 1977). Our specimens were collected from Atrina pectinata .

Remarks. Yang and Ko (2004) reported the zoeal stages of Conchodytes nipponensis , but the a collecting locality of their ovigerous individuals remains uncertain because they were purchased it at a fish market in Busan. Therefore, the present material is be the first certain record of this species collected in the Korean territorial waters. Our specimens agree well with Bruce’s description (1977), only the first pereopods are more slender. As we suggest that is due to a different developmental stage or sex. Bruce’s (1977) illustration is for a juvenile femal while an adult male is figured in this paper ( Fig. 3B ). Conchodytes nipponensis can be distinguished from other species of the genus by having the telson with 3 pairs of dorsolateral and 2 pairs of posterior spines, subequal length of carpus and merus of the first pereopod, and biunguiculate dactyli of third to fifth pereopods bearing a rounded proximoventral lobe with a small pointed tip ( Chace and Bruce, 1993). Until now, only brachyuran species, such as pinnotherid crabs, living in the Bivalvia have been reported from Korea ( Kim, 1973). Therefore, this species represents also the first finding of a caridean species living in the Bivalvia from Korean waters.

Distribution. Australia, Philippines, Japan ( Chace and Bruce, 1993), and now Korea.

Figures

Fig. 1. Conchodytes nipponensis (De Haan, 1844), an ovigerous female, in the mantle cavity of the pen shell Atrina pectinata.

Fig. 2. Conchodytes nipponensis, male (cl 8 mm). A. Habitus, dorsal. B. Habitus, lateral. C. Telson and uropod, dorsal. D. Right antennules, ventral. E. Right scaphocerite. Scale bars=1 mm.

Fig. 3. Conchodytes nipponensis, male (cl 8 mm). A. Right third maxilliped, ventral. B. Left first pereopod, medial. B′. Chela of first pereopod. C. Left second pereopod, dorsal. D. Left second pereopod, lateral. E-G. Left third to fifth pereopods, lateral. E′-G′. Dactyls of third to fifth pereopods. Scale bars=1 mm.