Specimens examined in this study have been deposited at the OceanTech Marine Institute (OTMI), Busan. Shield length (SL) is used as an indication of specimen size, measured from the tip of the rostrum to the midpoint of the posterior margin of the shield. For detailed observations of the integument surface structure, the specimens were stained with methylene blue. Terminology used here is mainly based on that of McLaughlin (2003).
Order Decapoda Latreille, 1802
Family Paguridae Latreille, 1802
[Fig. 1.] Catapaguroides fragilis (Melin, 1939). Male (SL 0.91 mm, OTMI 102). A, shield and cephalic appendages, dorsal; B, chela of right cheliped, dorsal; C, carpus of right cheliped, dorsal; D, chela of left cheliped, dorsal; E, carpus of left cheliped, dorsal; F, entire right cheliped, mesial; G, entire left cheliped, mesial. Scales: A-G = 0.5 mm.
[Fig. 2.] Catapaguroides fragilis (Melin, 1939). Male (SL 0.91 mm, OTMI 102). A, right second pereopod, lateral; B, left third pereopod, lateral; C, coxae of fifth pereopods, showing sexual tubes, ventral; D, telson. Scales: A, B = 0.3 mm, C = 0.25 mm, D = 0.12 mm.
Shield slightly longer than wide. Rostrum broadly rounded, slightly overreaching obsolete lateral projections. Ocular peduncles long and slender, shorter than shield. Antennular peduncles exceeding distal corneal margins by 0.3-0.5 times of the length of the ultimate segment. Antennal peduncles reaching approximately to distal corneal margins (Fig. 1A). Chelipeds distinctly unequal and dissimilar, and the right cheliped is larger than the left cheliped. Right cheliped with dactylus shorter than palm, with a single small spine proximally, and mesial margin rounded dorsomesially, dorsal surface with numerous long setae; palm elongate, approximately uniform from proximal to distal margin, dorsolateral margin with row of five longitudinal spines, dorsolateral margin unarmed, dorsoproximal margin with a prominent spine, dorsal surface with numerous long setae, carpus with row of five longitudinal dorsomedial spines (Fig. 1B, C, F). Left cheliped with dactylus slightly longer than palm, unarmed but with numerous long setae; palm shorter than carpus, dorsomesial margin with two spines, dorsal surface with long setae; carpus with three dorsomesial spines, dorsal surface with long setae (Fig. 1D, 1E, 1G). Ambulatory legs longer than right cheliped; dactyli unarmed with long stiff setae on dorsal surface, each ventral margin with row of corneous spines; propodi with two short to long, basally articulated bristles on ventrodistal margin (second) or unarmed (third) on dorsal and ventral surfaces; carpi with dorsodistal spinule (Fig. 2A, 2B). Right male sexual tube elongate, reaching beyond coxa of left fourth pereopod; left sexual tube very short (Fig. 2C). Telson with slightly asymmetrical, narrow, posterior lobes separated by deep median cleft; terminal margins each with two small spines, one slightly curved spine at posterolateral angle (Fig. 2D).
Southern Japan, Mururoa, depths of 22-75 m (Komai and Rahayu, 2013). South of Jeju Island, Korea, depth of 10 m (the present study).
The present specimens match the definition of the species by de Saint Laurent (1968), McLaughlin (2002), and Komai and Rahayu (2013) who reported the morphological characters of