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

White, Kristine N. & Reimer, James Davis, 2012, Commensal Leucothoidae (Crustacea, Amphipoda) of the Ryukyu Archipelago, Japan. Part II: sponge-dwellers, ZooKeys 166, pp. 1-58 : 30-32

Leucothoe toribe sp. n. Figures 1920

Type material.

Holotype male, 3.3 mm RUMF-ZC-1784, Manza, Okinawa–jima Island, Okinawa, reef wall (26°30'15"N, 127°50'39"E), among coral rubble, 10-23 m, K.N. White and N.S. White, col., 8 February 2011 (KNWOkinawa29K). Paratype female, 3.8 mm RUMF-ZC-1785, same station data as holotype.

Type locality.

Manza, Okinawa–jima Island, Okinawa, Japan (26°30'15"N, 127°50'39"E).

Additional material examined.

4 specimens, RUMF-ZC-1786, KNWOkinawa22C; 5 specimens, NSMT-Cr 21902, KNWOkinawa23D; 2 specimens, RUMF-ZC-1787, KNWOkinawa23E; 1 specimen, NSMT-Cr 21903, KNWOkinawa25E; 4 specimens, RUMF-ZC-1788, KNWOkinawa27D; 6 specimens, NSMT-Cr 21904, KNWOkinawa29K; 6 specimens, RUMF-ZC-1789, KNWOkinawa30E; 1 specimen, RUMF-ZC-1790, KNWOkinawa33G; 12 specimens, NSMT-Cr 21905, KNWOkinawa39J.

Diagnosis (male).

Head anterodistal margin concave. Mandibular palp article 3 shorter than article 1; left mandible with 5 robust marginal setae. Maxilla 1 palp 1-articulate. Maxilliped inner plates with facial setae. Gnathopod 1 basis distally expanded, posterior margin with 5 short proximal setae; carpus robust; propodus curved, palm smooth with 22 short distal setae; dactylus reaching 0.2 × propodus length. Gnathopod 2 carpus distally truncate, spoon-like, with setulate-serrate setae; propodus with 3 mediofacial setal rows; dactylus elongate. Pereopods 5-6 coxae with facial setae; epimeron 3 posteroventral corner sinuous.

Description (male).

Head. Anterior margin transverse, anterodistal margin concave; ventral cephalic keel anterior margin transverse, anteroventral margin rounded, ventral margin excavate; eyes with more than 10 ommatidia, round. Antenna 1 0.4 × body length, flagellum 10-articulate, peduncle article 1 width less than 2 × article 2, accessory flagellum 1-articulate. Antenna 2 0.3 × body length, slightly shorter than antenna 1, flagellum 6-articulate. Mandibular palp ratio of articles 1-3 1.0: 2.6: 0.8, article 2 with 2 medium distal setae, article 3 with 1 distal seta, incisors weakly dentate; left mandible with 1 row of 5 and 1 row of 4 raker spines, with 5 robust marginal setae, lacinia mobilis large, strongly toothed; right mandible with 9 raker spines, lacinia mobilis small, weakly dentate. 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 with 4 distal setae; outer plate with 6 distal robust setae and 6 distal setae. Maxilla 2 inner plate with 3 robust distal and 3 robust marginal setae; outer plate with 4 robust distal setae and 4 sets of 2 slender distal marginal setae. Maxilliped inner plates distal margin with a v-shaped indentation, with short robust setae, facial setae present; outer plate inner margin smooth, reaching 0.3 × palp article 1, with simple marginal setae, facial setae absent; palp article 4 subequal in length with article 3, distally acute.

Pereon. Coxae 1-4 relative widths 1.0: 1.4: 1.1: 1.2. Gnathopod 1 coxa smooth, with tiny marginal setae, anterodistal margin produced, rounded, distal margin rounded, posterior margin excavate, facial setae absent; basis distally expanded, anterior margin with 1 short seta, anterodistal margin with several short slender setae, posterior margin with 5 setae; ischium bare; carpus linear, distal length 5.3 × width, proximal margin smooth, distal margin with 5 short setae; propodus curved, palm smooth with 22 distal setae; dactylus smooth, reaching 0.2 × propodus length. Gnathopod 2 coxa as long as broad, subequal in size with coxa 3, smooth, with tiny marginal setae, anterior margin straight, anterodistally subquadrate, distal and posterior margins straight, facial setae absent; basis distally expanded, anterior margin with 9 short setae, posterior margin with 1 short seta; ischium bare; carpus 0.2 × propodus length, curved, distally truncate, spoon-like, anterior margin smooth with setulate-serrate setae; propodus with 3 mediofacial setal rows, primary mediofacial setal row above midline, reaching 0.9 × propodus length, secondary mediofacial setal row with 9 setae, tertiary mediofacial setal row with 4 setae, posterior margin smooth, palmar corner pronounced, palm convex with 4 major tubercles; dactylus curved, proximal margin smooth with 2 setae, anterior margin distally subacute, reaching 0.7 × propodus length. Pereopod 3 coxa length 1.5 × width, anterodistal corner overriding distal face of coxa 2 and extending below it, smooth, with tiny marginal setae, anterior margin straight, distal margin slightly convex, posterior margin straight, facial setae absent. Pereopod 4 coxa smooth, with tiny marginal setae, anterior margin straight, distal margin produced, posterior margin excavate, facial setae absent. Pereopods 5-6 coxae facial setae present. Pereopod 7 coxa facial setae absent. Pereopods 5-7 bases width length ratios 1: 1.3, 1: 1.2, 1: 1.1, posterior margins smooth, setose.

Pleon. Epimera 1-2 with ventral setae, epimeron 3 bare; epimeron 3 posteroventral corner sinuous, rounded. Uropods 1-3 relative lengths 1.0: 0.7: 1.0. Uropod 1 peduncle subequal in length with inner ramus, outer ramus 0.8 × inner ramus length; inner ramus with 3 robust setae; outer ramus with 4 robust setae. Uropod 2 peduncle and outer ramus 0,7 × inner ramus length; inner and outer rami each with 3 robust setae. Uropod 3 peduncle and outer ramus subequal in length with inner ramus; inner ramus with 3 robust setae; outer ramus with 2 robust setae. Telson 2.5 × longer than wide, apex weakly tridentate.

Female (sexually dimorphic characters).

Gnathopod 2 basis linear, posterior margin bare; ischium with 5 posterodistal setae; carpus 0.4 × propodus length, distally tapered.

Etymology.

After the Japanese word ‘toribe’, meaning ‘ladle’ and referring to the spoon-like carpus on gnathopod 2. (Pronounced toe-ree-bay)

Ecology.

In canals of green hard branching sponge,? Clathria (Thalysias) reinwardti (Figure 25F); and among coral rubble.

Relationships.

Leucothoe toribe sp. n. is similar to Leucothoe alata (Barnard, 1959), Leucothoe nagatai Ishimaru, 1985, and Leucothoe obuchii White & Reimer, 2012a in having gnathopod 1 carpus reaching 0.1-0.2 × propodus length, and a curved gnathopod 1 propodus, but differs in having a 1-articulate maxilla 1 palp, broad pereopod 5-7 bases, and a sinuous posteroventral margin on epimeron 3. Leucothoe toribe sp. n. shares the spoon-like gnathopod 2 carpus with Leucothoe alata as well.

Remarks.

Leucothoe toribe sp. n. is faint pink in color, darkest along pereonite edges (Figure 23H). This species has been collected only on Yakushima Island, Kagoshima and from both western and eastern coasts of Okinawa–jima Island, Okinawa.

Distribution.

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