Commensal Leucothoidae (Crustacea, Amphipoda) of the Ryukyu Archipelago, Japan. Part II: sponge-dwellers Author White, Kristine N. Author Reimer, James Davis text ZooKeys 2012 166 1 58 http://dx.doi.org/10.3897/zookeys.166.2313 journal article http://dx.doi.org/10.3897/zookeys.166.2313 1313-2970-166-1 Leucothoe lecroyae sp. n. Figures 910 Type material. Holotype male, 3.5 mm RUMF-ZC-1763, Kuse, Kakeroma-jima Island reef wall ( 28°06'05"N , 129°21'12"E ), in canals of brown sponge, Rhabdastrella of Thiele 1903 , 10 m, K.N. White, col., 19 March 2011 (KNWAmami2C). Paratype female, 3.3 mm RUMF-ZC-1764, same station data as holotype. Type locality. Kuse, Kakeroma-jima Island, Amami-oshima Island region, Kagoshima, Japan ( 28°06'05"N , 129°21'12"E ). Additional material examined. 7 specimens, NSMT-Cr 21894, KNWYaku3D; 7 specimens, RUMF-ZC-1765, KNWYaku3D; 1 specimen, RUMF-ZC-1766, KNWYaku5P; 3 specimens, NSMT-Cr 21895 KNWOkinawa44A; 1 specimen, RUMF-ZC-1767, KNWOkinawa44F; 5 specimens, NSMT-Cr 21893, KNWAmami2D; 1 male specimen, RUMF-ZC-1799, KNWAmami2C. Diagnosis (male). Ventral cephalic keel anterior margin transverse, anteroventral margin quadrate. Eyes oval. Antennae 1 accessory flagellum 1-articulate. Right mandible with small 2-layered lacinia mobilis. Maxilliped inner plates small with serrate robust setae; outer plate tuberculate. Gnathopod 1 coxa anterior margin serrate; carpus robust, proximal margin serrate; propodus palm serrate with triangular teeth. Gnathopod 2 carpus distally truncate; propodus with 2 mediofacial setal rows. Pereopods 5-7 coxae with facial setae; bases posteriorly serrate. Female ventral cephalic keel anteroventral margin serrate; gnathopod 1 basis posterior margin with 6 short setae; gnathopod 2 carpus distally tapered. Description (male). Head. Anterior margin rounded, anterodistal margin evenly rounded; ventral cephalic keel anterior margin transverse, anteroventral margin quadrate, ventral margin oblique; eyes with more than 10 ommatidia, oval. Antenna 1 0.4 x body length, flagellum 10+-articulate (broken), peduncle article 1 width less than 2 x article 2, accessory flagellum 1-articulate. Antenna 2 0.3 x body length, slightly shorter than antenna 1, flagellum 6-articulate. Mandibular palp ratio of articles 1-3 1.0: 2.8: 1.0, article 2 with 2 medium 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 7 raker spines, with small 2-layered lacinia mobilis, strongly dentate. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, setose; outer lobes with moderate gape, anterior margins setose. Maxilla 1 palp 1-articulate, margins constricted and with 4 distal setae; outer plate with 7 distal robust setae and 6 short marginal setae. Maxilla 2 inner plate with 4 robust distal setae, 2 robust facial setae, and 7 slender marginal setae; outer plate with 3 robust distal setae and 3 slender distal marginal setae. Maxilliped inner plates distal margin with a v-shaped indentation, with short simple and serrate robust setae; outer plate inner margin tuberculate, reaching 0.3 x 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: 1.5: 1.2: 1.8. Gnathopod 1 coxa smooth, with tiny marginal setae, anterior margin serrate, anterior margin produced, rounded, distal margin straight, posterior margin excavate, facial setae absent; basis linear, anterior margin with 1 short seta, posterior margin with 2 short setae; ischium bare; carpus linear, distal length 7.1 x width, proximal margin serrate, distal margin bare; propodus straight, palm serrate with 10 distal setae and 10 distal triangular teeth; dactylus smooth, reaching 0.1 x propodus length. Gnathopod 2 coxa broader than long, subequal in size with coxa 3, smooth, with tiny marginal setae, anterior margin expanded, anterodistally rounded, distal and posterior margins straight, facial setae absent; basis distally expanded, anterior margin with 10 medium setae, posterior margin with 2 short setae; ischium with 1 posterodistal seta; carpus 0.4 x propodus length, curved, distally truncate, anterior margin dentate; propodus with 2 mediofacial setal rows, primary mediofacial setal row above midline, reaching 0.8 x propodus length, secondary mediofacial setal row with 4 setae, with 1 row of submarginal setae, posterior margin with 5 small robust setae, palm convex with 10 tubercles; dactylus curved, proximal margin smooth with 1 seta, anterior margin distally subacute, reaching 0.5 x propodus length. Pereopod 3 coxa length 1.3 x width, anterodistal corner overriding distal face of coxa 2 and extending below it, smooth, with tiny marginal setae, anterior margin straight, distal margin oblique, posterior margin straight, facial setae absent. Pereopod 4 coxa smooth, with tiny marginal setae, anterior margin produced, distal margin evenly rounded, posterior margin tapered, facial setae absent. Pereopods 5-7 coxae facial setae present; bases width length ratios 1: 1.4, 1: 1.3, 1: 1.2, serrate, setose. Pleon . Epimera 1-2 with ventral setae, epimeron 3 bare; epimeron 3 posteroventral corner sinuous, rounded. Uropods 1-3 relative lengths 1.0: 0.8: 0.9. Uropod 1 peduncle subequal in length with inner ramus, outer ramus 0.9 x inner ramus length; inner ramus with 6 robust setae and outer ramus with 4 robust setae. Uropod 2 peduncle 0.9 x inner ramus length, outer ramus length 0.6 x inner ramus length; inner ramus with 4 robust setae and outer ramus with 3 robust setae. Uropod 3 peduncle 1.2 x inner ramus length, outer ramus length 0.9 x inner ramus length; inner ramus with 3 robust setae and outer ramus with 5 robust setae. Telson 2.3 x longer than wide, apex strongly tridentate. Female (sexually dimorphic characters). Ventral cephalic keel anteroventral margin serrate. Gnathopod 1 basis posterior margin with 6 short setae. Gnathopod 2 basis posterior margin with 1 seta; ischium with 2 distal and 2 posterodistal setae; carpus distally tapered, anterior margin smooth; propodus posterior margin bare. Figure 9. Leucothoe lecroyae sp. n., holotype male, 3.5 mm, RUMF-ZC-1763; paratype female, 3.3 mm, RUMF-ZC-1764. Figure 10. Leucothoe lecroyae sp. n., holotype male, 3.5 mm, RUMF-ZC-1763; paratype female, 3.3 mm, RUMF-ZC-1764. Etymology. Named for Sara E. LeCroy, in recognition of her contribution to amphipod taxonomy. Ms LeCroy has been a colleague and friend for the past 7 years and the first author is very grateful for all her support. Ecology. In canals of sponges, brown sponge with holes on top only, Rhadastrella sp., RUMF-ZP-1, KNWOkinawa16A (Figure 24H), dark red chimney sponge, Axinellidaeof Carter 1875 , RUMF-ZP-12, KNWYaku3F (Figure 24D), orange lumpy sponge, Axinellidae (Figure 24J); and among coral rubble. Relationships. Leucothoe lecroyae sp. n. is similar to Leucothoe cheiriserra Serejo, 1998, Leucothoe gavialis Myers, 1985, Leucothoe hipposideros White & Thomas, 2009, Leucothoe squalidens Ledoyer, 1984, and Leucothoe hashi sp. n. in having triangular teeth on the palm of gnathopod 1 propodus. It also shares a short dactylus on gnathopod 1, rounded head margin, and distally truncate gnathopod 2 carpus with Leucothoe hashi sp. n., but differs in having a more robust gnathopod 1 propodus and carpus, maxilla 1 palp 1-articulate, margins constricted, 2-layered lacinia mobilis on the right mandible, and wide pereopod 5-7 bases. Remarks. Leucothoe lecroyae sp. n. is faint yellow in color (Figure 23C). This species has been collected on Yakushima Island and Amami-oshima Island region (both Kagoshima) and from the northwestern and eastern coasts of Okinawa-jima Island, Okinawa, Japan. Distribution. East China Sea: Okinawa-jima Island (Okinawa), Amami-oshima Island, Yakushima Island (both Kagoshima), Japan.