Ampithoe waialua J.L. Barnard, 1970

Kim, Kyung-Won, Zhang, Xin, Choi, Jae-Hong, Kim, Jun & Kim, So-Yeon Shin and Young-Hyo, 2023, Amphipods (Crustacea: Malacostraca) fauna from Chujado Island in Korea, Journal of Species Research 12 (1), pp. 1-26 : 2-4

7. Ampithoe waialua J.L. Barnard, 1970

ăêėùầNjạ (ṵAE)* ( Figs. 2 , 3 , 6G )

Ampithoe waialua J.L. Barnard, 1970: 53 , Figs. 20, 21; Peart & Lörz, 2018: 27.

Material examined. 2 inds., Jikgudo Island, 29 August 2021.

Description. Male (MABIK CR00252863): Body ( Fig. 2A ) 11.6 mm long; Head subquadrate, about 1.3 times as long as wide. Rostrum absent; cephalic lobe truncate. Eye subcircular and medium, located close to cephalic lobe; Pereonites and pleonites smooth.

Pleonites 1 - 3 ( Fig. 2B ) without ventral seta, epimeral plates 2, 3 rounded-quadrate posteroventrally, somewhat concave midposteriorly.

Antenna 1 ( Fig. 2C ) slender, about 0.5 times of the body length; peduncular article 1 setose posteriorly; length ratio of peduncular articles 1 - 3 = 1.00: 0.85: 0.28; accessory flagellum absent; flagellum 32-articulate, about 1.75 times as long as peduncle.

Antenna 2 ( Fig. 2D ) setose, about 0.8 times as antenna 1, peduncular article 2 broader than others, with 4 robust setae ventrally; length ratio of peduncular articles 3 - 5 = 1.00: 0.90: 0.15; flagellum 27-articulates, about 0.9 times as long as peduncle.

Gnathopod 1 ( Fig. 2E ) coxa subtrapezoidal, produced anterodistally, with several setules ventrally; basis moderate, with rounded anterodistal lobe; merus produced into triangular expansion posterodistally; carpus about 0.7 times length to propodus, with 4 robust setae on proximal half of anterior margin; propodus subrectangular, palm short, concave; dactylus falcate, overreaching palm; length ratio of articles 2 - 7 = 1.00: 0.34: 0.60: 0.63: 0.85: 0.53.

Gnathopod 2 ( Fig. 2F ) similar to gnathopod 1; coxa rounded quadrate, with setules ventrally; basis subrectangular with large rounded anterodistal lobe; carpus subtriangular, with 6 robust setae on proximal half of anterior margin, rounded posterior lobe setaceous; propodus large, about 1.4 times as long as carpus; palm strongly excavate, curved concavely, palmar corner delimited by subacute process; dactylus falcate, inner margin serrulate, 0.5 times as long as propodus.

Pereopod 3 ( Fig. 2G ) coxa subquadrate, ventral margin with setules ventrally; basis moderate, subrectangular, with simple setae posteriorly; length ratio of articles 2 - 7 = 1.00: 0.27: 0.36: 0.32: 0.34: 0.22.

Pereopod 4 ( Fig. 2H ) similar to pereopod 3, but basis more setose.

Pereopod 5 ( Fig. 3A ) coxa bilobate, dorsodistal protruding lobe roundly backward; basis expanded, about 1.2 times wider than deep; merus and carpus moderate, subrectangular; propodus comparatively slender than carpus; length ratio of articles 2 - 7 = 1.00: 0.30: 0.62: 0.55: 0.85: 0.32.

Pereopod 6 ( Fig. 3B ) basis subovate, 1.69 times as long as wide; merus slightly longer than carpus; propodus narrow, subrectangular, posterior margin with 3 robust setae; length ratio of articles 2 - 7 = 1.00: 0.21: 0.61: 0.55: 0.64: 0.25.

Pereopod 7 ( Fig. 3C ) similar with pereopod 6, except basis slightly wider than that of pereopod 6, posterior margin serrulate; length ratio of articles 2 - 7 = 1.00: 0.28: 0.63: 0.61: 0.80: 0.21.

Uropod 1 ( Fig. 3D ) peduncle rectangular, 1.34 times as long as inner ramus, with 6 dorsolateral, 8 dorsomedial, 3 ventrolateral robust setae; outer ramus shorter than inner one.

Uropod 2 ( Fig. 3E ) subsimilar in structure but about 0.7 times shorter than uropod 1; peduncle armed with 1 dorsolateral and 2 dorsomedial robust setae; outer ramus subequal to peduncle and slightly shorter than inner ramus.

Uropod 3 ( Fig. 3F ) short, peduncle cylindrical, 2.6 times as long as outer ramus, outer ramus bearing 2 hooked terminal spines, inner ramus with group of setae apically.

Telson ( Fig. 3G ) entire, subtriangular, 1.3 times as wide as long, with lateral and subapical setae.

Female (DKUAMP202205), Body length 7.8 mm. similar to male in shape, but gnathopods 1, 2 sexually dimorphic.

Gnathopod 1 ( Fig. 3H ) similar to that of male, but propodus palm rounded, not concave, defined by 1 small robust seta; length ratio of articles 2 - 7 = 1.00: 0.31: 0.38: 0.57: 0.61: 0.35.

Gnathopod 2 ( Fig. 3I ) similar to that of male, but propodus palm much less-excavate, defined by 2 stout robust setae; length ratio of articles 2 - 7 = 1.00: 0.32: 0.40: 0.51: 0.65: 0.38.

Remarks. Ampithoe waialua is similar to A. dalli Shoemaker, 1938 in possessing similar shaped antennae and gnathopods. However, A. waialua is morphologically distinguished from A. dalli as follows: (1) gnathopod 1 with excavated palm; (2) pereopod 5, anterior notch of basis with strong robust seta; and (3) epimeral plate 3 rounded-quadrate posteroventrally. Ampithoe waialua also similar to A. platycera Sivaprakasam, 1970 . However, A. waialua can be distinguished from A. platycera as follows: (1) antenna 2, peduncular article 4 is not flat; (2) gnathopods 1 and 2, propodi elongate; and (3) gnathopod 2, palmar corner without robust seta. The newly recorded species in Chujado Island, A. waialua is well in accord with the original description given by J.L. Barnard (1970).

Distribution. Korea (Chujado Island), Hawaiian Islands.

Figures

Fig. 2. Ampithoe waialua J.L. Barnard, 1970, adult male A, habitus; B, pleonal epimera 1-3; C, antenna 1; D, antenna 2; E, gnathopod 1; F, gnathopod 2; G, pereopod 3; H, pereopod 4. Scale bars:A=1 mm; B-H=0.5 mm.

Fig. 3. Ampithoe waialua J.L. Barnard, 1970, adult male (A-G). A, pereopod 5; B, pereopod 6; C, pereopod 7; D, uropod 1; E, uropod 2; F, uropod 3. G, telson; Ampithoe waialua J.L. Barnard, 1970, adult female (H, I). H, gnathopod 1; I, gnathopod 2. Scale bars: A-C=0.5 mm; D-I=0.2 mm.

Fig. 6.A, Byblis japonicus; B, Hourstonius koreana; C, Paramphilochus parachelatus; D. Ampithoe changbaensis; E. Ampithoe lacertosa; F. Ampithoe valida shimizuensis; G. Ampithoe waialua; H. Pleonexes koreana.