Leucothoe kebukai, White, Kristine N. & Reimer, James Davis, 2012

White, Kristine N. & Reimer, James Davis, 2012, Commensal Leucothoidae (Crustacea, Amphipoda) of the Ryukyu Archipelago, Japan. Part III: coral rubble-dwellers, ZooKeys 173, pp. 11-50 : 31-34

Leucothoe kebukai sp. n. Figures 11 12

Type material.

Holotype male, 2.2 mm RUMF-ZC-1865, Yona, Kunigami, Okinawa–jima Island, Okinawa, reef wall (26°45'56"N, 128°11'46"E), among coral rubble, 9 m, K.N. White and N.S. White, col., 23 October 2010 (KNWOkinawa15H). Paratype female, 2.6 mm, RUMF-ZC-1866, Kaminomine, Tokunoshima Island, Kagoshima, patch reef (27°46'11"N, 129°02'19"E), among coral rubble, 1 m, K.N. White and N.S. White, col., 20 September 2010 (KNWTokuno1A).

Type locality.

Yonna, Kunigami, Okinawa–jima Island, Okinawa, Japan (26°45'56"N, 128°11'46"E).

Additional material examined.

1 specimen, NSMT-Cr 22002, KNWOkinawa14D; 1 specimen, RUMF-ZC-1867, KNWOkinawa15H; 3 specimens, NSMT-Cr 22003, KNWOkinawa15H; 1 specimen, NSMT-Cr 22004, KNWOkinawa19B;1 specimen, RUMF-ZC-1868, KNWOkinawa19C; 1 specimen, RUMF-ZC-1869, KNWOkinawa31C; 1 specimen, NSMT-Cr 22005, KNWOkinawa33F; 3 specimens, RUMF-ZC-1870, KNWOkinawa34L; 7 specimens, NSMT-Cr 22006, KNWOkinawa53E; 1 specimen, RUMF-ZC-1871, KNWOkinawa60A; 1 specimen, NSMT-Cr 22007, KNWTokuno3C; 3 specimens, RUMF-ZC-1872, KNWTokuno3E; 2 specimens, NSMT-Cr 22008, KNWTokuno4G; 1 specimen, RUMF-ZC-1873, KNWYaku1E; 1 specimen, NSMT-Cr 22009, KNWYaku2D.

Diagnosis (male).

Head anterior margin truncate, distal margin oblique, convex. Right mandible lacinia mobilis represented by a small ridge. Maxilla 1 palp 1-articulate, margins constricted. Gnathopod 1 carpus and propodus curved; dactylus reaching 0.2 × propodus length. Gnathopod 2 basis anterior margin with 7 long setae; carpus distally truncate, spoon-like. Pereopods 5-6 coxae with facial setae; bases broadly expanded.

Description (male).

Head. Anterior margin truncate, anterodistal margin subquadrate, distal margin oblique, convex; ventral cephalic keel anterior margin transverse, anteroventral margin subquadrate, ventral margin straight; eyes present with more than 10 ommatidia, round. Antenna 1 0.4 × body length, flagellum 7-articulate, peduncle article 1 width less than 2 × article 2, accessory flagellum absent. Antenna 2 0.3 × body length, shorter than antenna 1, flagellum 7-articulate. Mandibular palp ratio of articles 1-3 1.0: 3.0: 0.6, article 2 with 2-3 distal setae, article 3 with 1distal seta, incisors weakly dentate; left mandible with 9 raker spines, lacinia mobilis large, strongly toothed; right mandible with 7 raker spines, lacinia mobilis represented by a small ridge. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, bare; outer lobes with moderate gape, anterior margins setose. Maxilla 1 palp 1-articulate, margins constricted, with 3 distal slender setae; outer plate with 6 distal robust setae. Maxilla 2 inner plate with 3 slender distal, 3 marginal, and 1 facial seta; outer plate with 4 distal slender setae and 4 marginal slender setae. Maxilliped inner plates distal margin with v-shaped indentation, with short simple robust setae; outer plate inner margin smooth, reaching 0.1 × palp article 1, facial setae absent; palp article 4 subequal in length with article 3, distally acute.

Pereon. Coxae 1-4 relative widths 1.0: 1.1: 1.1: 1.2. Gnathopod 1 coxa smooth, with tiny marginal setae, anterodistal margin produced, rounded, distal margin rounded, posterior margin slightly excavate, facial setae absent; basis distally expanded, anterior margin with 1 medium seta, posterior margin bare; ischium bare; carpus curved, distal length 7.4 × width, proximal margin smooth, distal margin with 1 seta; propodus curved, palm smooth with 12 distal setae; dactylus smooth, reaching 0.2 × propodus length. Gnathopod 2 coxa longer than broad, slightly larger than coxa 3, smooth, with tiny marginal setae; anterior margin rounded, anterodistally rounded, distal margin rounded, posterior margin straight, facial setae absent; basis distally expanded, anterior margin with 7 long setae, posterior margin bare; ischium with 3 posterodistal setae; carpus 0.2 × propodus length, curved, distally truncate, spoon-like, anterior margin smooth; propodus with 1 mediofacial setal row above midline, reaching 0.6 × propodus length, with 1 row of submarginal setae, posterior margin smooth, palm convex, with 3 small tubercles; dactylus curved, proximal margin smooth, bare, anterior margin distally acute, reaching 0.5 × propodus length. Pereopod 3 coxa length 0.9 × width, anterodistal corner overriding distal face of coxa 2, not extending below it, smooth, with tiny marginal setae, anterior margin rounded, distal and posterior margins straight, facial setae absent. Pereopod 4 coxa smooth, with tiny marginal setae, anterior and distal margins rounded, posterior margin tapered, facial setae absent. Pereopods 5-6 coxae facial setae present, pereopod 7 coxa facial setae absent. Pereopods 5-7 bases width length ratios 1: 1.5, 1: 1.5, 1: 1.6, posterior margins smooth, setose.

Pleon. Epimera 1-2 with ventral setae, epimeron 3 bare, posteroventral corner subquadrate, produced. Uropods 1-2 relative lengths 1.0: 0.9. Uropod 1 peduncle 1.0 × inner ramus length, outer ramus 0.8 × inner ramus length; inner and outer rami each with 2 robust setae. Uropod 2 peduncle 1.1 × inner ramus length, outer ramus 0.9 × inner ramus length; inner ramus with 3 robust setae, outer ramus with 2 robust setae. Uropods 1-2 inner and outer rami with robust setae. Uropod 3 missing. Telson 1.8 × longer than wide, apex tridentate.

Female (sexually dimorphic characters).

Gnathopod 1 basis distally expanded, anterior margin with 4 short setae; carpus distal margin bare; propodus palm with 13 distal setae. Gnathopod 2 basis anterior margin with 6 long setae, posterior margin with 1 posterodistal seta; ischium with 2 distal and 4 posterodistal setae; carpus distally tapered. Uropod 3 peduncle 0.9 × inner ramus length, outer ramus subequal in length with inner ramus; inner ramus with 4 robust setae, outer ramus with 3 robust setae.

Etymology.

After the Japanese word ‘kebukai’, meaning ‘hairy’ and referring to the long setae on gnathopod 2 basis anterior margin (pronounced kay-boo-kigh).

Ecology.

Host unknown, presumably in sponges in coral rubble.

Relationships.

Leucothoe kebukai sp. n. shares a distinctly curved and inflated gnathopod 1 propodus and a short gnathopod 1 dactylus with Leucothoe alata Barnard, 1959, Leucothoe nagatai Ishimaru, 1985, Leucothoe obuchii White & Reimer, 2012a, and Leucothoe trulla . Leucothoe kebukai sp. n. differs from all of these species in the following: maxilla 1 palp with an unclear articulation; gnathopod 2 basis anterior margin with seven long setae, ischium with posterodistal setae, propodus slender, and dactylus short.

Remarks.

Leucothoe kebukai sp. n. is translucent yellow in color with faint pink stripes along pereonite edges (Figure 15E). This species is endemic to the central and northern Ryukyu Islands.

Distribution.

East China Sea: Okinawa–jima Island (Okinawa), Tokunoshima Island, Yakushima Island (both Kagoshima), Japan.