Leucothoe thula, White & Thomas, 2009

White, Kristine N. & Thomas, James Darwin, 2009, Leucothoidae *, Zootaxa 2260 (1), pp. 494-555 : 538-541

Leucothoe thula sp. nov.

( Figs 27 , 28 )

Type material. Holotype, male, 2.7 mm, AM P 71122, 500 m north-east of North Point, Lizard Island (14°38.700'S 145°27.213'E), sponges, asteroid, solitary corals, hydroids, soft bottom with forams, crinoids, Halimeda macroloba , Halimeda cylindracea , Caulerpa taxifolia , Gracilaria sp. , Lobophora sp. and sediment, 23 m, C. Serejo, 27 February 2005 ( QLD 1710). Paratype, female, 3.2 mm, AM P 79817, same station data.

Additional material examined. 1 female, AM P 71022 ( QLD 1709 ) .

Type locality. North Point , Lizard Island, Queensland, Australia (14°38.700'S 145°27.213'E) .

Etymology. After the Latin ‘ thule ’, meaning ‘farthest north’ and referring to the type locality.

Description. Based on holotype, male, 2.7 mm, AM P71122.

Head. Head length less than pereonite 1+2, anterior margin rounded, without serrations or teeth, anterodistal margin rounded without cusp, ventral cephalic keel rounded, rostrum small to medium; eyes with 10 or more ocelli, distally concave. Antenna 1 0.3 x body length; flagellum 6-articulate, peduncle width less than 2 x article 2; article 3 shortened. Antenna 2 0.3 x body length, shorter than antenna 1; flagellum 4- articulate. Mandibles lacking molars, palp 3-articulate, ratio of articles 1 – 3, 1.0:2.5:1.4, article 2 with 6 distal setae, article 3 with 2 distal setae, incisors strongly dentate; left mandible lacinia mobilis large, strongly toothed, with 9 accessory setae; right mandible lacinia mobilis small, with 8 accessory setae. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, bare; outer lobes with moderate gape, anterior margins continually setose. Maxilla 1 palp 1-articulate with 4 distal setae; outer plate with 6 distal spines and 3 distal setae. Maxilla 2 inner plate with 3 robust setae and 8–10 thin distal setae; outer plate with 10–11 distal setae. Maxilliped inner plates fused, distal margin with v-shaped indentation, with short spines and long setae; outer plate smooth, reduced, reaching less than half of palp article 1, with 6 distal setae and 1 distal spine; palp 4-articulate, article 4 slender, very slightly curved.

Pereon. Coxae 1–4 relative widths 1.0:0.8:0.7:1.4. Gnathopod 1 coxa smooth, bare, anterodistal corner produced, subtriangular, distal margin rounded, posterodistal margin narrowly rounded, with 1 long facial seta; basis constricted proximally, anterior margin with 2 – 5 setae, posterior margin bare; ischium bare; carpus and propodus distally tapered; carpus 9.3 x longer than wide, proximal margin serrate, distal margin setose; propodus straight, palm serrate with 4 long and 10 – 15 short distal setae; dactylus smooth, reaching 0.3 x propodus length. Gnathopod 2 coxa length 1.2 x width, slightly wider than coxa 3, smooth, bare, anterodistally rounded, distal margin evenly rounded, posterior margin straight, facial setae absent; basis constricted proximally, without tubercles or serrations, anterior margin with 5–8 setae, posterior margin bare; ischium with 1 posterior and 2 posterodistal setae; carpus 0.5 x propodus length, curved, distally tapered, anterior margin smooth; propodus posterior margin without teeth/serrations, with 1 mediofacial setal row below midline, reaching 0.8 x propodus length, 1 row of 7 submarginal setae, palm convex with 3 minor projections; dactylus recurved, proximal margin smooth, anterior margin distally acute, reaching 0.8 x propodus length. Pereopod 3 coxa length 1.7 x width, anterodistal corner over-riding distal face of coxa 2 and extending below it, smooth, setose, anterior margin evenly rounded, distal margin tapered, posterior margin straight, with 3 facial setae. Pereopod 4 coxa smooth, setose, anterior margin rounded, distal margin evenly rounded, posterior margin excavate, facial setae absent. Pereopods 5–6 coxa each with 2 distal facial setae. Pereopod 7 coxa facial setae absent. Pereopods 6–7 missing. Pereopod 5 basis width length ratio 1:1.3, posterior margin smooth, setose.

Pleon. Epimeron 1 with tuft of 3 anteroventral setae. Epimeron 2 with 3 ventral setae. Epimeron 3 bare, posteroventral margin subquadrate. Uropods 1–2 subequal in length; inner and outer ramus lined with short marginal setae; peduncle 0.8 x inner ramus length. Uropod 1 outer and inner ramus subequal in length; both rami with robust setae. Uropod 2 outer ramus 0.7 x inner ramus length; inner ramus with robust setae; outer ramus with 1 robust seta. Uropod 3 missing. Telson 2.6 x longer than wide, apex tridentate.

Female (sexually dimorphic characters). Based on paratype, female, 3.2 mm, AM P79817. Epimera 1–2 bare. Habitat. In sponges, asteroid corals, solitary corals, hydroids, forams, crinoids, Halimeda macroloba Decaisne, 1841 , Halimeda cylindracea Decaisne, 1842 , Caulerpa taxifolia ( Vahl, 1802) , a species of Gracilaria Greville, 1830 and a species of Lobophora J. Agardh, 1894 .

Remarks. Leucothoe thula sp. nov. shares its uni-articulate maxilla 1 palp with L. hipposideros sp. nov., L. laevipalma sp. nov., L. odontiskos sp. nov., L. pollexa sp. nov., L. sparsa sp. nov. and L. undulata sp. nov. This character has not been found in any described Leucothoe to date, although an “indistinct suture” in the maxilla 1 palp has been reported in L. assimilis , L. basilobata , L. cheiriserra and L. urospinosa . The anteroventral setal tuft on epimeron 1 is shared with L. alcyone , L. ashleyae , L. assimilis , L. bidens , L. furina , L. germanalcyone , L. saron and L. sparsa . The profusely displaced gnathopod 2 mediofacial setal row has only been recorded in L. commensalis , L. wuriti and L. epidemos sp. nov. to date. The facial and marginal setae on coxa 3 and 5 respectively are shared only with L. epidemos , L. pollexa and L. sparsa .

Distribution. Australia. Queensland: Lizard Island (current study).

Figures

FIGURE 27. Leucothoe thula sp. nov., holotype, male, 2.7 mm, AM P71122 (QLD 1710), North Point, Lizard Island, Great Barrier Reef.

FIGURE 28. Leucothoe thula sp. nov., holotype, male, 2.7 mm, AM P71122; paratype, female, 3.2 mm, AM P79817 (QLD 1710), North Point, Lizard Island, Great Barrier Reef.