Cumella arguta Gamô, 1962

Lee, Chang-Mok & Lee, Kyung-Sook, 2012, A new species and new record of the genus Cumella (Cumacea: Nannastacidae) from Korea, Zootaxa 3390, pp. 19-32 : 26-31

Cumella arguta Gamô, 1962

( Figs. 5–8 )

Cumella arguta Gamô, 1962 , p. 195, figs. 30, 31; 1963, p 87; 1967, p. 251; Liu & Liu, 1990, p. 218, fig. 18; Bäcescu, 1992, p. 214.

Cumella scabera Gamô, 1962 , p. 192, figs. 28, 29; 1963, p 87; 1967, p. 251.

Material examined. 4 males, Sapsido Is., Boryeong-si, 36° 21ʹ 3ʹʹN, 126° 21ʹ 47ʹʹE, 8 May 1993, (B.J. Kang); 119 males, 47 females, Port Seogwipo, Jejudo Is., 33° 14ʹ 16ʹʹN, 126° 34ʹ 5ʹʹE, 29 October 1993, (B.J. Kang); 4 males, 1 female, Port Jeju, Jejudo Is., 33° 31ʹ 14ʹʹN, 126° 32ʹ 10ʹʹE, 30 October 1993, (B.J. Kang); 15 males, 3 females, Port Jisepo, Geojedo Is., 34° 49ʹ 49ʹʹN, 128° 42ʹ 20ʹʹE, 28 June 1995, (B.J. Kang); 9 males, Deokjeokdo Is., Ongjingun, 37° 13ʹ 17ʹʹN, 126° 8ʹ 40ʹʹE, 20 September 1998; 51 males, 11 females, Daecheongdo Is., Ongjin-gun, 37° 49ʹ 12ʹʹN, 124° 42ʹ 33ʹʹE, 10 August 1998; 34 males, 2 females, Socheongdo Is., Ongjin-gun, 37° 46ʹ 6ʹʹN, 124° 47ʹ 7ʹʹE, 12 August 1999; 2 males, 16 females, Cheongsando Is., Wando-gun, 34° 10ʹ 52ʹʹN, 126° 51ʹ 20ʹʹE, 20 May 1998; 256 males, 65 females, Port Jangseungpo, Geojedo Is., 34° 5ʹ 54ʹʹN, 128° 43ʹ 27ʹʹE, 3 July 1998 (Y.H. Kim); 4 males, Oeyeondo Is., Boryeong-si, 36° 13ʹ 32ʹʹN, 126° 4ʹ 52ʹʹE, 6 October 2000 (Y.H. Kim); 5 males, Port Anpo, Yeosu-si, 34° 38ʹ 12ʹʹN, 127° 38ʹ 21ʹʹE, 30 March 2004 (Y.H. Kim).

Type locality. Tanabe Bay, Kii peninsula, Japan.

Description. Male. Body ( Figs. 5 A–C) 1.9 mm long, excluding uropods, covered with abundant tiny alveolate sculpturing, aciform processes and hair-like setae.

Carapace ( Figs. 5 A, B) 0.35 times as long as body length, 1.8 times as long as deep, 1.75 times as long as wide, nearly rectangular in dorsal view, shallowly depressed near both dorsolateral sides of middle portions, with 1 pair of ridges on both posterolateral margins, dorsomedian carina faintly marked, with 2–5 teeth on frontal lobe, 1 tooth on median portion and 1 tooth on posterior portion; antennal notch concave; anterolateral margin round, smooth, pseudorostral lobes serrated; ocular lobe broadly round, with 3 lenses.

Thorax ( Figs. 5 A, B) 0.55 times as long as carapace length, 0.2 times as long as body length.

Abdomen ( Fig. 5 A) 0.9 times as long as cephalothorax.

Antenna 1 ( Fig. 5 D) peduncle triarticulate; first article 0.6 times as long as remaining articles combined, with 3 simple distal setae on inner margin, second article equal to third one, inner corner with 3 simple setae; main flagellum triarticulate, second article with 1 aesthetasc, 1 long simple seta on distal margin, third article subequal to second one, with 1 asthetasc, 1 sensory seta, 2 simple long setae; accessory flagellum biarticulate, 1.15 times as long as first article of main flagellum, with 1 sensory seta, 4 simple setae on terminal margin.

Antenna 2 ( Fig. 5 E) not extending beyond pleonite 5; peduncle 5-articulate, second article with 2 plumose setae on inner margin.

Maxilliped 3 ( Fig. 6 A) basis 1.5 times as long as remaining articles combined, inner margin with numerous hair-like setae, 3 plumose setae, outer corner inflated, reaching to about 1/3 point of merus, with 2 long plumose setae and 1 short simple seta.

Pereopod 1 ( Fig. 5 F) basis 0.85 times as long as remaining articles combined, inner margin serrated, with 1 short and 1 long simple distal setae, numerous hair-like setae, outer margin with 2 rows of flattened hyaline teeth and 2 simple distal setae; carpus 2.3 times as long as dactylus, with 2 simple setae on inner margin, with 3 plumose setae on outer margin.

Pereopod 2 ( Fig. 5 G) basis 1.4 times as long as remaining articles combined, with 1 plumose seta, 1 short simple seta near inner corner, outer margin with 2 rows of flattened hyaline teeth and 1 simple distal seta; dactylus 1.3 times as long as carpus, with 3 simple setae on surface, 3 setae (one of them very long) on terminal margin.

Pereopod 3 ( Fig. 6 B) basis 1.8 times as long as remaining articles combined, with 1 row of hyaline flattened teeth and 4 simple setae on outer margin.

Pereopod 4 ( Fig. 6 C) basis 1.15 times as long as remaining articles combined.

Pereopod 5 ( Fig. 6 D) basis 0.55 times as long as remaining articles combined.

Uropod ( Fig. 6 E) peduncle 1.4 times as long as pleonite 6, with 1 row of serrations and 1 row of simple setae on dorsal surface, inner margin strongly serrated, with 3 short simple and 2 stout setae; endopod uniarticulate, 0.7 times as long as peduncle, inner margin serrated, with 4 short stout setae, terminal margin with 1 short simple, 1 pectinated and 1 strong setae; exopod biarticulate, 0.85 times as long as the length of endopod, second article with 1 simple seta on surface, 2 terminal setae (one of them very long, shorter than exopod length).

Female. Body ( Fig. 7 A) 1.7 mm long, excluding uropods, surface same as in male.

Carapace ( Figs. 7 A–C) 0.35 times as long as body length, 1.5 times as long as deep, 1.9 times as long as wide, nearly triangular in dorsal view, prominently depressed on both lateral sides of middle and rear portions, dorsomedian carina well marked, with 1–4 teeth on frontal lobe, 1 tooth on median portion and 1 tooth on posterior portion; antennal notch more concave than in male, anterolateral margin rectangular, serrated.

Thorax ( Figs. 7 A, C) 0.55 times as long as carapace length, 0.2 times as long as body length; anterior margins of first and second segments serrated.

Abdomen ( Fig. 7 A) 0.85 times as long as cephalothorax.

Antenna 1 ( Fig. 7 D) peduncle triarticulate; first article 0.6 times as long as remaining articles combined, with 3 simple distal setae on inner margin, second article equal to third one, with 3 simple setae on inner corner; main flagellum triarticulate, second article with 1 aesthetasc and 1 long simple seta on distal margin, third article subequal to second one, with 1 asthetasc seta, 1 sensory seta, and 2 simple long setae; accessory flagellum biarticulate, subequal to first article of main flagellum, with 1 sensory seta and 4 simple setae on terminal margin.

Maxilliped 3 ( Fig. 7 E) basis subequal to length of remaining articles combined, with 1 strong plumose distal seta on inner corner, outer corner inflated, reaching to about 1/2 point of merus, with 2 plumose setae and 1 short simple seta.

Pereopod 1 ( Fig. 7 F) basis 0.55 times as long as remaining articles combined, inner margin serrated, with 4 simple distal setae, outer margin with 1 row of flattened hyaline teeth and 2 simple distal setae.

Pereopod 2 ( Fig. 8 A) basis 0.65 times as long as remaining articles combined, with 1 simple seta on inner margin, inner corner with 1 plumose seta and 1 simple seta on outer margin.

Pereopod 3 ( Fig. 8 B) basis 0.8 times as long as remaining articles combined, with 1 sensory seta on outer margin, inner margin with 4 simple setae and 1 plumose seta on terminal margin.

Pereopod 4 ( Fig. 8 C) basis 0.65 times as long as remaining articles combined.

Pereopod 5 ( Fig. 8 D) basis 0.45 times as long as remaining articles combined.

Uropod ( Fig. 8 E) peduncle 1.2 times as long as pleonite 6, with 1 row of serrations on dorsal surface, inner margin serrated, with 3 simple setae; endopod uniarticulate, 0.85 times as long as peduncle, inner margin serrated, with 1 short stout seta, terminal margin with 1 short simple, 1 pectinated and 1 strong setae; exopod same as in male.

Distribution. Far East Asia ( China, Korea, Japan).

Remarks. The Korean female specimens of Cumella arguta correspond with the original description by Gamô (1962), based on only female specimens from Japanese waters. However, Korean specimens have some variations in the number of teeth present along the dorsomedian carina of the carapace, with 3–7 teeth in the female and 4–8 teeth in the male. The Korean female specimens of C. arguta are very similar to C. alaskensis Gerken (2009) , based on only female specimen from the shores of southeast Alaska, in that the carapace has several teeth along the dorsomedian carina. But C. arguta can easily be distinguished from C. alaskensis by the proportion and armature of the uropod (see Gerken, 2009).

The Korean male specimens of C. arguta undoubtedly match the description of C. scabera Gamô (1962) based only on adult male specimens because of following common features: 1) the surface of the carapace has a pair of ridges on both posterolateral margins; 2) the carapace has a row of teeth on frontal lobe (the number of the tooth occurs 2–5 variously); 3) the proportion and armature of the carpus of the pereopod 1 is the same (2.3 times as long as dactylus, with 2 simple inner setae and 3 plumose outer setae); 4) the proportion and armature of the uropod endopod is the same (0.7 times as long as peduncle, with 4 short stout setae on inner margin). Also, the proportion and armature of the pereopod 2 is the same. Consequently, we deal with C. scabera as a synonym of C. arguta which is widely known. We assume that Gamô may have not found that this species has some variations in the number of teeth present along the dorsomedian carina of the carapace.

Figures

FIGURE 5. Cumella alveata Gamô, 1962, male, 1.9 mm, Port Jangseung, Geojedo Is., Korea: A, habitus, lateral; B, cephalothorax, dorsal; C, surface of carapace; D, antenna 1; E, antenna 2; F, pereopod 1; G, pereopod 2. Scale bars = 0.5 mm (A, B), 0.2 mm (F), 0.1 mm (C – E, G).

FIGURE 6. Cumella alveata Gamô, 1962, male, 1.9 mm, Port Jangseungpo, Geojedo Is., Korea: A, maxilliped 3; B, pereopod 3; C, pereopod 4; D, pereopod 5; E, uropod and pleonite 6, dorsal. Scale bars = 0.3 mm (A – E).

FIGURE 7. Cumella alveata Gamô, 1962, female, 1.7 mm, Port Jangseungpo, Geojedo Is., Korea: A, habitus, lateral; B, carapace of other specimen; C, cephalothorax, dorsal; D, antenna 1; E, maxilliped 3; F, pereopod 1. Scale bars = 0.5 mm (A – C), 0.3 mm (F), 0.1 mm (D, E).

FIGURE 8. Cumella alveata Gamô, 1962, female, 1.7 mm, Port Jangseungpo, Geojedo Is., Korea: A, pereopod 2; B, pereopod 3; C, pereopod 4; D, pereopod 5; E, uropod and pleonite 6, dorsal. Scale bars = 0.3 mm (A – E).