Leucothoe zanpa, 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 : 33-35

Leucothoe zanpa sp. n. Figures 2122

Type material.

Holotype male, 3.2 mm, RUMF-ZC-1791, Zanpa Cape, Okinawa–jima Island, Okinawa, reef wall (26°26'27"N, 127°43'03"E), in canals of large white ball sponge, Tetillidae , 30 m, Daisuke Ueno, col., 26 February 2011 (KNWOkinawa34A). Paratype female, 3.8 mm, RUMF-ZC-1792, same station data as holotype.

Type locality.

Cape Zanpa, Okinawa–jima Island, Okinawa, Japan (26°26'27"N, 127°43'03"E).

Additional material examined.

12 specimens, RUMF-ZC-1793, KNWOkinawa34A; 13 specimens, NSMT-Cr 21906, KNWOkinawa34A; 3 specimens, RUMF-ZC-1794, KNWOkinawa34B; 2 specimens, NSMT-Cr 21907, KNWOkinawa34B.

Diagnosis (male).

Eyes rectangular. Antenna 1 0.6 × body length, peduncle article 1 width greater than 2 × article 2. Gnathopod 1 coxa about ½ as wide as coxa 2; basis proximally inflated, elongate; carpus and propodus elongate. Gnathopod 2 basis posterior margin with 2 long setae; ischium with 5 long posterodistal setae; propodus with 1 row of robust submarginal setae. Pereopod 5 coxa with facial setae; pereopods 5-7 bases very narrowly expanded. Uropod 3 peduncle 1.5 × inner ramus length. Telson apex truncate.

Description (male).

Head. Anterior margin excavate, anterodistal margin subquadrate; ventral cephalic keel anterior margin excavate, anteroventral margin rounded, ventral margin straight; eyes with more than 10 ommatidia, rectangular. Antenna 1 0.6 × body length, flagellum 6-articulate, peduncle article 1 width greater than 2 × article 2, accessory flagellum absent. Antenna 2 0.5 × body length, slightly shorter than antenna 1, flagellum 3-articulate. Mandibular palp ratio of articles 1-3 1.0: 2.0: 1.3, article 2 with 4-5 short distal setae, article 3 with 2 distal setae, incisors strongly dentate; left mandible with 8 raker spines, lacinia mobilis large, strongly toothed; right mandible with 12 raker spines, lacinia mobilis small, strongly dentate. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, bare; outer lobes with large gape, anterior margins setose. Maxilla 1 palp 2-articulate with 4 distal setae; outer plate with 4 distal robust setae and 7 distal setae. Maxilla 2 inner plate with 5 robust distal setae and 1 slender facial seta; outer plate with 4 robust distal setae, 7 distal and 5 proximal slender marginal setae. Maxilliped inner plates fused, distal margin with a v-shaped indentation, with short robust setae; outer plate inner margin tuberculate, reaching 0.1 × palp article 1, with simple marginal setae, facial setae present; palp article 4 subequal in length with article 3, distally acute.

Pereon. Coxae 1-4 relative widths 1.0: 1.9: 1.7: 1.7. Gnathopod 1 coxa smooth, with tiny marginal setae, anterior margin straight, anterodistal margin subquadrate, distal margin straight, posterior margin excavate, facial setae absent; basis proximally inflated, anterior margin with 4 setae, posterior margin with 2 setae; ischium bare; carpus linear, distal length 14.1 × width, proximal margin with denticles, distal margin bare; propodus curved, palm serrate with 13 distal setae; dactylus smooth, reaching 0.2 × propodus length. Gnathopod 2 coxa longer than broad, subequal in size with coxa 3, smooth, with tiny marginal setae, anterodistally rounded, distal margin straight, posterior margin straight, facial setae absent; basis linear, anterior margin with 5 short setae, posterior margin with 2 long setae; ischium with 5 long posterodistal setae; carpus 0.4 × propodus length, straight, distally tapered, anterior margin smooth; propodus with 1 mediofacial setal row displaced to midline, reaching 0.6 × propodus length, with 1 row of robust submarginal setae, posterior margin smooth, palm convex with many small tubercles; dactylus curved, proximal margin smooth, bare, anterior margin distally subacute, reaching 0.6 × propodus length. Pereopod 3 coxa length 0.8 × width, anterodistal corner overriding distal face of coxa 2, not extending below it, smooth, with tiny marginal setae, anterior margin evenly rounded, distal and posterior margins straight, facial setae absent. Pereopod 4 coxa smooth, with tiny marginal setae, anterior margin straight, distal margin evenly rounded, posterior margin straight, facial setae absent. Pereopod 5 coxa facial setae present, pereopods 6-7 coxae facial setae absent. Pereopods 5-7 bases width length ratios 1: 1.8, 1: 1.9, 1: 1.7, posterior margins smooth, setose.

Pleon. Epimera 1 and 3 bare, epimeron 2 with ventral setae; epimeron 3 posteroventral corner rounded. Uropods 1-3 relative lengths 1.0: 0.7: 0.8. Uropod 1 peduncle and outer ramus subequal in length with inner ramus; inner ramus with 1 robust seta; outer ramus lined with short marginal setae, with 5 robust setae. Uropod 2 peduncle 0.9 × inner ramus length, outer ramus 0.8 × inner ramus length; inner ramus with 2 robust setae; outer ramus lined with short marginal setae, with 2 robust setae. Uropod 3 peduncle 1.5 × inner ramus length, outer ramus subequal in length with inner ramus; inner ramus lined with short marginal setae, without robust setae; outer ramus with 3 robust setae. Telson 2.0 × longer than wide, apex truncate.

Female (sexually dimorphic characters).

Antenna 1 0.2 × body length. Antenna 2 0.3 × body length, subequal in length with antenna 1. Gnathopod 1 basis proximally wider than in male, posterior margin with 11 long setae. Gnathopod 2 basis anterior margin with 10 short setae.

Etymology.

After the Japanese place name ‘Zanpa’, meaning 'wave slicing’ and referring to the type locality.

Ecology.

In canals of large white ball sponge, Tetillidae (Figure 24I).

Relationships.

Leucothoe zanpa sp. n. is similar to Leucothoe oboa Karaman, 1971, Leucothoe occulta Krapp-Schickel, 1975, and Leucothoe pachycera Della Valle, 1893, in having antennae 1 peduncle article 1 width greater than 2 × the width of article 2, but differs in having an excavate anterior head margin, tuberculate maxilliped inner plate, setose gnathopod 2 basis posterior margin, pereopods 5-7 bases without facial setae, bare epimera 1 and 3, subquadrate epimeron 3 posteroventral margin, and truncate telson apex. Leucothoe zanpa sp. n. is similar to Leucothoe elegans White & Reimer, 2012a in the gracefully elongate gnathopod 1, but differs in eye shape, antennae length, and pereopod 5-7 bases widths.

Remarks.

Leucothoe zanpa sp. n. is white in color with faint purple stripes along pereonite edges (Figure 23B). This species is endemic to Zanpa Cape on the western coast of Okinawa–jima Island, Okinawa.

Distribution.

East China Sea: Okinawa–jima Island, Okinawa, Japan.