Leucothoe batillum, White & Machida, 2018

White, Kristine N. & Machida, Ryuji J., 2018, Taiwanese Leucothoidae (Crustacea: Amphipoda), Including Three New Species from Dongsha Atoll., Zoological Studies 57 (47), pp. 1-22 : 9-12

publication ID	https://doi.org/ 10.6620/ZS.2018.57-47
publication LSID	lsid:zoobank.org:pub:F347BCBB-F9D5-4A2B-8A01-8CB1183889A9
persistent identifier	https://treatment.plazi.org/id/4884D455-66F6-4FDE-84E7-A77F1D08D94A
taxon LSID	lsid:zoobank.org:act:4884D455-66F6-4FDE-84E7-A77F1D08D94A
treatment provided by	Felipe
scientific name	Leucothoe batillum
status	sp. nov.

Treatment

Leucothoe batillum View in CoL sp. nov.

( Figs. 3F View Fig , 4-5 View Fig View Fig )

urn:lsid:zoobank.org:act:4884D455-66F6-4FDE-84E7-A77F1D08D94A

Material Examined: Holotype: male, 4.3 mm, NMMB-CD 5583 KNW-Dongsha-2017-1d, Dongsha Atoll north beach, 20°42'18.26"N, 116°43'43.290"E, 1.5 m, 29 May 2017, K.N. White collector GoogleMaps . Paratype: female, 4.1 mm, NMMB-CD 5584, same station data as Holotype.

Other: 1 male, 1 female, 1 juvenile; ASIZCR000421, KNW-Dongsha-2017-3f, Dongsha Atoll lagoon, 20°42'14.76"N, 116°48'17.2074"E, 11 m; 21 May 2017; K.N. White, collector. 4 females, 1 juvenile; KNW-Dongsha-2017-12d, Dongsha Atoll south beach, 20°47'57.48"N, 116°43'24.07"E, 1.7 m; 27 May 2017; K.N. White, collector.

Etymology: From the Latin ‘ batillum ’ meaning ‘shovel, fire pan’ and referring to the shovel-like gnathopod 2 carpus in males of this species, used as noun in apposition.

Diagnosis: Head anterior margin round. Ventral cephalic keel anterior margin excavate, anteroventral margin quadrate with a simple cusp. Eyes oval ( Fig. 4A View Fig ). Accessory flagellum present, 1-articulate ( Fig. 4B View Fig ). Gnathopod 1 dactylus reaching 0.2 × propodus length ( Fig. 4C View Fig ). Gnathopod 2 carpus distally truncate, resembling a shovel, serrate; propodus with one mediofacial setal row slightly displaced toward midline ( Fig. 4F View Fig ). Telson apex evenly rounded ( Fig. 5B View Fig ).

Description (male holotype): Head: Anterior margin rounded, anterodistal margin evenly rounded; ventral cephalic keel anterior margin excavate, anteroventral margin quadrate with a simple cusp, ventral margin oblique; eyes with more than 10 ommatidia, oval. Antenna 1 0.3 × body length, flagellum 7-articulate, peduncle article 1 width slightly wider than article 2 ( Fig. 4A View Fig ), accessory flagellum present, 1-articulate ( Fig. 4B View Fig ). Antenna 2 0.2 × body length, shorter in length than antenna 1, flagellum 3-articulate ( Fig. 4A View Fig ).

Mandibular palp ratio of articles 1-3 1.0:3.2:2.0, article 2 with 6 marginal setae, article 3 with 2 distal setae, incisors weakly dentate ( Fig. 5F View Fig ); left mandible with 13 raker spines, lacinia mobilis large, weakly toothed ( Fig. 5E View Fig ); right mandible with 13 raker spines, lacinia mobilis small ( Fig. 5F View Fig ). Maxilla 1 palp 2-articulate, with 4 distal slender setae; outer plate with 6 distal robust setae and 3 slender setae ( Fig. 4H View Fig ). Maxilla 2 inner plate with 7 marginal and distal robust setae, outer plate with 3 distal robust setae and several slender marginal setae ( Fig. 4G View Fig ). Maxilliped inner plates distal margin rounded, with short simple robust setae; outer plate inner margin smooth, reaching 0.4 × palp article 1; palp article 4 thick, subequal in length with article 3, distally acute ( Fig. 5G View Fig ).

Pereon: Coxae 1-4 relative widths 1.0: 1.2: 0.8: 1.4 ( Fig. 4A View Fig ).

Gnathopod 1 coxa anterodistal margin produced with notch, distal margin straight, posterior margin concave; basis distally slightly expanded, anterior margin with 3 short setae, posterior margin bare; ischium bare ( Fig. 4C View Fig ); carpus curved, distal length 9 × width, distally very narrow, smooth, anterior margin with small short setae ( Fig. 4E View Fig ); propodus straight, palm dentate with short setae; dactylus smooth, reaching 0.2 × propodus length ( Fig. 4D View Fig ).

Gnathopod 2 coxa subquadrate, wider than coxa 3, smooth, margins slightly rounded; basis slightly distally expanded, anterior margin with 4 short setae, posterior margin with 1 distal seta; ischium with 1 distal seta; carpus 0.4 × propodus length, curved, setose, distally truncate, resembling a shovel, serrate; propodus with one mediofacial setal row slightly displaced to midline, reaching 0.8 × propodus length, submarginal setal row of 6 setae, anterior margin gently curved, smooth, palm with 5 medium tubercles; palmar corner clearly defined as prominent hump, remaining posterior margin straight; dactylus curved, proximal margin smooth, bare, anterior margin distally acute, reaching 0.6 × propodus length ( Fig. 4F View Fig ).

Pereopod 3 coxa smooth, anterior margin rounded, distal margin rounded, oblique, posterior margin straight. Pereopod 4 coxa smooth, anterior margin expanded, distal margin straight, posterior margin convex. Pereopods 5-7 bases width length ratios 1: 1.1, 1: 1.1, 1:1.0, posterior margins bare; pereopods 5-6 bases posterior margins smooth, pereopod 7 basis posterior margin serrate ( Fig. 4A View Fig ).

Pleon: Epimeron 1 anterodistal margin with 1 seta; Epimeron 2 distal margin with 3 setae; Epimeron 3 bare, posteroventral corner rounded ( Fig. 4A View Fig ). Uropods 1-3 relative lengths 1.0: 0.6: 0.8. Uropod 1 peduncle 1.3 × inner ramus length, outer ramus 0.9 × inner ramus length; inner and outer rami each with 3 robust setae. 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 subequal in length with inner ramus, outer ramus 0.8 × inner ramus length; inner and outer rami each with 2 robust setae ( Fig. 4A View Fig ). Telson 2.1 × longer than wide ( Fig. 5A View Fig ), apex rounded, beset with four short setae ( Fig. 5B View Fig ).

Female paratype (sexually dimorphic characters): Gnathopod 1 basis anterior margin with six short setae ( Fig. 5H View Fig ). Gnathopod 2 carpus distally tapered, smooth, not spoon-like; propodus palm with 3 small tubercules ( Fig. 5C View Fig ).

Color pattern: When alive this species has yellow antenna 1 peduncle articles 1 and 2, a red-orange striped “saddle” pattern on pereonites 2-5, and a red dot coxa 4 ( Fig. 3F View Fig ).

Ecology: This species was collected among Halimeda and coral rubble.

Relationships: Leucothoe batillum sp. nov. resembles Leucothoe assimilis Barnard, 1974 , Leucothoe epidemos White and Thomas, 2009 , Leucothoe makromatos White and Thomas, 2009 , Leucothoe tarte Barnard, 1974 , and Leucothoe trulla White and Reimer, 2012a in having a round anterior head margin, a long gnathopod 1 dactylus, and a truncate gnathopod 2 carpus. The shovelshape of the gnathopod 2 carpus is unique to L. batillum sp. nov., with the carpus of all of the other species being more fluted or spoon-like. The displaced mediofacial setal row on gnathopod 2 propodus is shared with L. makromatos and L. trulla . The other species listed here have a mediofacial setal row above the midline. The rounded telson found in L. batillum sp. nov. is not shared by any of these species, with a blunt simple telson in L. assimilis and a tridentate tip found in the other species.