Korean nannastacids have recorded only eight species belonging to genera
Family Nannastacidae Bate, 1866 has 25 genera with approximately 430 species worldwide (Gerken, 2012). Among the 25 genera,
Thorax (Fig. 1A, B) almost half length of carapace, slightly shorter than 1/5 of body; lateral margins strongly serrated. Pereonite 1 very short, concealed in lateral view; pereonites 2-5 with 1 pair of obtuse teeth dorsodistally, respectively. Abdomen (Fig. 1A, B) subequal in length to cephalothorax; pleonites 1-2 with 2 pairs of obtuse teeth on dorsal and lateral surfaces, respectively; pleonite 6 with 2 pairs of simple setae on dorsal surface.
Pereopod 1 (Fig. 1C): basis 0.45 times as long as remaining articles combined, with 1 row of serrations and 1 simple proximal seta medially. Ischium with 2 simple setae. Merus with 3 simple setae. Dactylus 0.70 times as long as propodus, with 2 simple and 1 long stout setae terminally.
Pereopod 2 (Fig. 1D): basis 1.15 times as long as remaining articles combined, with 1 row of hyaline flattened teeth, outer margin with 1 simple seta distally, inner margin with 5 simple setae. Dactylus 1.65 times as long as propodus, with numerus hairs, 1 medial, 2 lateral, and 4 terminal setae.
Pereopod 3 (Fig. 1E): basis 0.40 times as long as remaining articles combined, inner margin with 1 simple seta, outer margin with 2 simple setae and 2 complex pedunculate setae.
Uropod (Fig. 1F): peduncle short, subequal in length to half of pleonite 6, inner margin with numerous hairs. Endopod not articulated, 2.40 times as long as peduncle, inner margin serrated, with 1 short simple, 2 complex pedunculate, and 1 small stout setae; terminal margin with 1 small simple and 1 long stout setae. Exopod not articulated, very short, subequal to 1/9 length of endopod, with 1 short and 1 long stout setae (reaching to about 5/6 point of endopod) terminally.
Adult male (cat no. DKUCUM 201602): body (Fig. 2A) about 2.4 mm long, excluding uropods; surface (Fig. 2A, B) same as in female. Carapace (Fig. 2A, B) subequal to 1/3 length of body, 1.40 times as long as width, 1.80 times as long as depth; width 1.25 times as long as depth; subrectangular in dorsal view, swollen near both branchial regions. Antennal notch (Fig. 2A, B) shallowly concave; antero-lateral margin subrectangular, serrate, with 1 strong tooth and 4 simple setae. Pseudorostral lobes (Fig. 2A, B) and ocular lobe (Fig. 2B) same as in female.
Thorax (Fig. 2A, B) almost half length of carapace, 1/5 length of body. Pereonite 1 very short, concealed in lateral view; pereonite 2 with 1 pair of dorsal teeth; pereonites 3-4 with 2 pairs of obtuse teeth dorsodistally, respectively; pereonite 5 long, with 1 pair obtuse teeth dorsodistally, respectively. Abdomen (Fig. 2A, B) subequal in length to cephalothorax; pleonites 1-2 with 1 pair of obtuse teeth dorsodistally, respectively; pleonite 6 with 2 pairs of simple setae dorsodistally and 2 pairs of small setae terminally, respectively; pleonites 1-6 with lateral serrated grooves.
Antenna 1 (Fig. 2C): peduncle composed of 3 articles; first article slightly shorter than remaining articles combined, with numerous hairs, and with 11 simple distal setae in outer margin; second article 0.45 times as long as first one, with 2 simple setae on outer corner; inner corner very inflated, longer than 1/2 length of third article, with 3 complex pedunculated setae distally; third article subequal in length to second one, with 3 complex pedunculate setae on distal margin. Main flagellum composed of 2 articles, slightly longer than last article of peduncle; second article with 1 simple seta and 2 aesthetascs terminally. Accessory flagellum not articulated, with 2 simple and 1 complex pedunculate setae.
Antenna 2 (Fig. 2A, D) slightly extending beyond end of pleonite 6; peduncle 5-articulate, second and third articles with 1 pappose seta.
Maxilliped 3 (Fig. 2E): basis slightly longer than remaining articles combined, outer margin with 1 row of serrations, inner margin with numerous hairs and 3 distal plumose setae; outer corner very inflated, reaching to about 1/2 length of merus, with 2 long plumose setae. Ischium with 1 plumose seta on inner coner. Merus with 1 plumose seta on inner margin and 1 long plumose seta on outer coner. Dactylus with 1 simple, 1 microserrate, 2 long stout, and 1 serrate setae terminally.
Pereopod 1 (Fig. 2F): basis 0.70 times as long as remaining articles combined, with 1 row of serrations, 1 row of hyaline flattened teeth, and 2 distal simple setae on outer margin, 1 microserrate seta and 1 row of serrations near distal margin. Ischium and merus with 2 simple setae. Dactylus 0.70 times as long as propodus, with 3 simple and 1 long stout setae terminally.
Pereopod 2 (Fig. 3A): basis subequal in length to remaining articles combined, with 1 row of serrations, 1 row of hyaline flattened teeth, and 3 distal simple setae on outer margin, 1 row of serrations and 2 simple distal setae near inner corner. Dactylus 1.55 times as long as propodus, with numerus hairs, 1 medial, 2 lateral, and 4 terminal setae.
Pereopod 3 (Fig. 3B): basis 0.90 times as long as remaining articles combined.
Pereopod 4 (Fig. 3C): basis 0.75 times as long as remaining articles combined.
Pereopod 5 (Fig. 3D): basis 0.45 times as long as remaining articles combined.
Uropod (Fig. 3E): peduncle 0.86 times as long as pleonite 6, with numerous hairs on inner margin. Endopod not articulated, 2.50 times as long as peduncle; inner margin serrated, with 5-6 small stout setae; terminal margin with 1 small simple and 1 long stout setae. Exopod not articulated, very short, subequal to 1/13 length of endopod, with 1 short setae and 1 long stout seta (reaching to about 3/5 point of endopod) terminally.
Korean name:1*두눈올챙이새우속 (신칭), 2*두드러기두눈올챙이새우 (신칭)