Taiwanese Leucothoidae (Crustacea: Amphipoda), Including Three New Species from Dongsha Atoll. Author White, Kristine N. The University of Tampa, Biology, 401 W. Kennedy Blvd., Tampa, FL 33606 U. S. A. Author Machida, Ryuji J. The University of Tampa, Biology, 401 W. Kennedy Blvd., Tampa, FL 33606 U. S. A. & Biodiversity Research Center, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529 Taiwan. & The University of Tampa, Biology, 401 W. Kennedy Blvd., Tampa, FL 33606 U. S. A. text Zoological Studies 2018 2018-09-27 57 47 1 22 http://dx.doi.org/10.6620/ZS.2018.57-47 journal article 10.6620/ZS.2018.57-47 1810-522X PMC6517761 31966287 12825927 F347BCBB-F9D5-4A2B-8A01-8CB1183889A9 Leucothoe cracentis sp. nov. ( Figs. 3G , 6-7 ) urn:lsid:zoobank.org:act: 457D5DF7-464A-46B1-BEE0- 315C9AA6930A Material Examined : Holotype : male, 1.8 mm , NMMB-CD 5585 , KNW-Dongsha-2017-4b, Dongsha Atoll southeast fore reef, 20°38'11.4"N , 116°54'25.85"E , 17 m ; 22 May 2017 ; K.N. White , collector . Paratype : female, 2.2 mm , NMMB-CD 5586, same station data as Holotype . Other : 1 male , 2 females , ASIZCR000422, same station data as Holotype . 2 males , 3 females , same station data as Holotype . Etymology : Derived from the Latin ‘ cracens ’ meaning ‘slender, graceful, neat’ and referring to the overall appearance of gnathopod 1. Diagnosis : Head anterior margin oblique, produced, distal margin straight. Eyes round. Accessory flagellum present, 1-articulate. Mandibular palp article 3 short, 0.9 × length of article 1. Gnathopod 1 carpus stout, anterior margin dentate; propodus slightly inflated, palm smooth; dactylus reaching 0.1 × propodus length. Gnathopod 2 carpus distally truncate, serrate. Pereopods 5-6 bases anterior and posterior margins nearly parallel, pereopod 7 basis posteriorly moderately produced. Description (male holotype ) : Head: Anterior margin oblique, produced, distal margin straight; ventral cephalic keel anterior margin excavate, anteroventral margin rounded, ventral margin straight; eyes with more than 20 ommatidia, round. Antenna 1 0.5 × body length, flagellum 7-articulate, peduncle article 1 width subequal to article 2, accessory flagellum present, 1-articulate. Antenna 2 0.4 × body length, shorter in length than antenna 1, flagellum 5-articulate. Mandibular palp ratio of articles 1-3 1.0:2.3:0.9, article 2 with 2 marginal setae, article 3 with 2 distal setae, incisors nearly smooth; left mandible with 12 raker spines, lacinia mobilis large, strongly toothed; right mandible broken. Maxilla 1 palp 2-articulate, with 3 distal slender setae; outer plate with 2 distal robust spines, 4 distal robust setae and 3 slender setae. Maxilla 2 inner plate with 2 marginal and 4 distal slender setae, outer plate with 3 distal slender setae. Lower lip inner lobes with moderate gape ( Fig. 7B ). Maxilliped inner plates distal margin rounded, v-shaped, with short simple robust setae; outer plate inner margin smooth, not extended up toward palp article 1; palp article 4 subequal in length with article 3, distally narrowing and acute. © 2018 Academia Sinica, Taiwan Fig. 6. Leucothoe cracentis sp. nov. male holotype, scale bars represent 0.1 mm; (A) Habitus; (B) Antenna 1 enlarged; (C) Maxilla 2; (D) Maxilla 1; (E) Maxilliped; (F) Gnathopod 2 medial; (G) Gnathopod 1 medial: (H) Gnathopod 1 carpus enlarged. © 2018 Academia Sinica, Taiwan Fig. 7. Leucothoe cracentis sp. nov. female paratype, scale bars represent 0.1 mm; (A) Gnathopod 2 medial; (B) Lower lip; (C) Epimeron 1-3; (D) left Mandible; (E) Gnathopod 1 medial; (F) Gnathopod 1 propodus and carpus enlarge(D); (G) Telson; (H) Telson enlarged. © 2018 Academia Sinica, Taiwan Pereon : Coxae 1-4 relative widths 1.0: 1.1: 1.1: 1.4. Gnathopod 1 coxa anterodistal margin produced, rounded, distal margin rounded with posterior notch, posterior margin convex; basis slightly distally expanded, anterior margin bare, posterior margin with 2 short setae; ischium bare; carpus distally curved, distal length 9 × width, anterior margin dentate with small short setae; propodus slightly inflated, palm smooth with short setae; dactylus smooth, reaching 0.1 × propodus length. Gnathopod 2 coxa subquadrate, subequal in width with coxa 3, smooth, margins slightly rounded; basis not expanded, stout, anterior margin with 2 short setae, posterior margin bare; ischium bare; carpus 0.4 × propodus length, curved, setose, distally truncate, serrate; propodus with one high mediofacial setal row reaching 0.7 × propodus length, submarginal setal row with 4 setae, anterior margin gently curved, smooth, palm with 2 large and many small tubercles; posterior margin straight; dactylus curved, proximal margin smooth, bare, anterior margin distally subacute, reaching 0.6 × propodus length. Pereopod 3 coxa anterior margin straight, distal margin slightly rounded with anterior and posterior notches, posterior margin straight. Pereopod 4 coxa smooth, antero-distally produced, anterior margin straight, distal margin rounded, posterior margin tapered. Pereopods 5-7 bases width length ratios 1: 1.5, 1: 1.3, 1:1.1, posterior margins smooth and setose; pereopods 5-6 bases with anterior and posterior margin nearly parallel, pereopod 7 basis posteriorly moderately produced. Pleon : Epimeron 1 with 1 long anterodistal seta; epimeron 2 distal margin with 2 short setae; epimeron 3 bare, posteroventral corner subquadrate. Uropods 1-3 relative lengths 1.0: 0.7: 1.0. Uropod 1 peduncle subequal in length with inner ramus, outer ramus 0.9 × inner ramus length; inner ramus with 2 robust setae; outer ramus with 1 robust seta. Uropod 2 peduncle 0.9 × inner ramus length, outer ramus 0.7 × inner ramus length; inner and outer rami each with 2 robust setae. Uropod 3 peduncle 0.7 × inner ramus length, outer ramus 0.9 × inner ramus length; inner and outer rami each with 2 robust setae. Telson 1.9 × longer than wide, apex tridentate, beset with two short setae. Female (sexually dimorphic characters) : Gnathopod 1 basis distally expanded, anterior margin with 2 short setae, posterior margin bare; carpus anterior margin smooth. Gnathopod 2 mediofacial setal row reaching 0.8 × propodus length. Epimeron 1 with 2 anterodistal setae. Color pattern : When alive this species has yellow antennae and a white snowflake pattern on coxa 4. Ecology : This species was collected among coral rubble. Relationships : Leucothoe cracentis sp. nov. resembles Leucothoe alata Barnard, 1959 , Leucothoe dentata Ledoyer, 1973 , Leucothoe lihue Barnard, 1970 , Leucothoe micronesiae Barnard, 1965 , Leucothoe rudicula White and Thomas, 2009 , in having round eyes, gnathopod 1 with stout carpus and short dactylus. L. cracentis is unique in having a strongly dentate gnathopod 1 carpus anterior margin. The distally truncate gnathopod 2 carpus is also shared with L. alata , L. lihue , L. rudicula , and Leucothoe venetiarum Soika, 1949 , but it is only serrate in L. cracentis sp. nov. The short mandibular palp article 3 is shared with L. alata , L. lihue , and L. micronesiae . Distribution : Dongsha Atoll, Taiwan (this study).