Leucothoe pollexa, White & Thomas, 2009

White, Kristine N. & Thomas, James Darwin, 2009, Leucothoidae *, Zootaxa 2260 (1), pp. 494-555 : 525-528

Leucothoe pollexa sp. nov.

( Figs 19 , 20 )

Type material. Holotype, male, 4.8 mm, AM P 79815; Picnic Beach , Palfrey Island , Lizard Island (14°41.70'S 145°26.92'E), subtidal, protected beach, poorly sorted coral sand with pieces of old coral, 0.3 m, S. E. LeCroy, 3 July 2001 ( SEL /LZI-2-2) . Paratype, female, 4.9 mm, AM P 79816; Casuarina Beach , Lizard Island (14°40.77'S 145°26.85'E), subtidal, protected beach, fine, slightly muddy sand, 0.5 m, S. E. LeCroy, 5 July 2001 ( SEL /LZI-5-1) .

Additional material examined. 1 female, AM P 70624 ( QLD 1621 ) ; 1 male, AM P 70953 ( QLD 1697 ) ; 4 females, 2 juveniles, AM P 79868 ( SEL /LZI-1-1) ; 2 females, 1 juvenile, GCRL2890 ( SEL /LZI-1-1) .

Type locality. Palfrey Island , Lizard Island, Queensland, Australia (14°41.70'S 145°26.92'E) .

Etymology. After the Latin ‘ pollex ’, meaning ‘thumb’ and referring to the subapical tooth on the gnathopod 2 carpus.

Description. Based on holotype, male, 4.8 mm, AM P79815.

Head. Head length less than pereonite 1+2, anterior margin truncate, without serrations or teeth, anterodistal margin rounded without cusp, ventral cephalic keel subquadrate, rostrum small to medium; eyes with 10 or more ocelli, round. Antenna 1 0.3 x body length; flagellum 8-articulate, peduncle width less than 2 x article 2, article 3 short. 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, 1.0:3.6:1.9, article 2 with 4 distal setae, article 3 with 2 distal setae, incisors strongly dentate; left mandible lacinia mobilis large, strongly toothed, with 8 accessory setae; right mandible lacinia mobilis small, with 7 accessory setae. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, bare; outer lobes with moderate gape, anterior margins weakly setose. Maxilla 1 palp 1-articulate with 3 distal setae; outer plate with 7 distal spines and 2 distal setae. Maxilla 2 inner plate with 3 distal setae; outer plate with 3 robust and 9–11 thin distal setae. Maxilliped inner plates fused, distal margin evenly rounded, with short spines and long setae; outer plate smooth, vestigial, barely exceeding margin of palp article 1, with 3 distal setae and 1 distal spine; palp 4- articulate, article 4 slender, recurved.

Pereon. Coxae 1–4 relative widths 1.0:1.2:1.0:1.3. Gnathopod 1 coxa smooth, bare, anterodistal corner produced, narrowly rounded, distal margin rounded, posterodistal margin subquadrate, with 1 facial seta; basis constricted proximally, anterior and posterior margins bare; ischium bare; carpus and propodus distally tapered; carpus length 10 x width, proximal margin serrate, distal margin setose; propodus straight, palm serrate with 4 – 5 distal setae; dactylus smooth, reaching 0.2 x propodus length. Gnathopod 2 coxa length 0.8 x width, slightly wider than coxa 3, smooth, bare, anterodistally rounded, distal margin evenly rounded, posterior margin straight, facial setae absent; basis slightly constricted proximally, without tubercles or serrations, anterior and posterior margins bare; ischium bare; carpus 0.3 x propodus length, curved with large subdistal tooth, anterior margin serrate; propodus posterior margin with few small teeth/serrations, with 1 mediofacial setal row above midline, reaching 0.8 x propodus length, 1 row of 8 submarginal setae, palm linear with 3 major projections; dactylus strongly recurved, proximal margin smooth, anterior margin distally acute, reaching 0.7 x propodus length. Pereopod 3 coxa length 1.3 x width, anterodistal corner over-riding distal face of coxa 2 and extending below it, smooth, bare, anterior margin evenly rounded, distal margin oblique, posterior margin evenly rounded, facial setae absent. Pereopod 4 coxa smooth, bare, anterior margin straight, distal margin produced, posterior margin excavate, facial setae absent. Pereopods 5–7 coxa facial setae absent; basis width length ratios 1:1.3, 1:1.3, 1:1.2, posterior margins smooth, bare.

Pleon. Epimera 1–3 bare. Epimeron 2 with 2 ventral setae. Epimeron 3 posteroventral margin with bidentate notch. Uropods 1–3 relative lengths 1.0:0.7:1.1; inner and outer ramus lined with short setae, with robust setae. Uropod 1 peduncle subequal in length with outer and inner ramus. Uropod 2 peduncle 0.8 x inner ramus length; outer ramus 0.6 x inner ramus length. Uropod 3 peduncle and outer ramus subequal to inner ramus length. Telson 2.7 x longer than wide, apex tridentate.

Female (sexually dimorphic characters). Based on paratype, female, 4.9 mm, AM P 79816. Gnathopod 1 basis anterior margin with 4 – 5 setae; ischium with 3 posterior setae. Gnathopod 2 basis with 5–8 anterior and 5 – 6 posterior setae; propodus palm projections less prominent; carpus distally truncate, without subdistal tooth. Pereopods 3+5–7 coxa with facial setae. Epimeron 1 with 2 anteroventral setae .

Habitat. In coral rubble and muddy sand from intertidal beach.

Remarks. Leucothoe pollexa sp. nov. shares its strongly recurved gnathopod 2 dactylus with L. rudicula sp. nov. The epimeron 3 bidentate notch is found in Leucothoe alcyone Imbach, 1967 , Leucothoe bidens Hirayama, 1985 c and Leucothoe germanalcyone Hirayama 1992 a . Leucothoe pollexa shares its uni-articulate maxilla 1 palp with L. hipposideros sp. nov., L. laevipalma sp. nov., L. odontiskos sp. nov., L. sparsa sp. nov., L. thula 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 . Leucothoe pollexa shares facial setae on the coxa with L. epidemos sp. nov., L. sparsa and L. thula Leucothoe pollexa shares its gnathopod 2 carpus subdistal tooth with L. assimilis , L. diemensis , Leucothoe furina Savigny, 1816 , Leucothoe incisa Stebbing 1897 , L. laticoxa , L. orkneyi and Leucothoe spinicarpa ( Abildgaard, 1789) .

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

Figures

FIGURE 19. Leucothoe pollexa sp. nov., holotype, male, 4.8 mm, AM P79815 (SEL/LZI-2-2), Picnic Beach, Palfrey Island, Great Barrier Reef; paratype, female, 4.9 mm, AM P79816 (SEL/LZI-5-1), Casuarina Beach. Lizard Island, Great Barrier Reef.

FIGURE 20. Leucothoe pollexa sp. nov., holotype, male, 4.8 mm, AM P79815 (SEL/LZI-2-2), Picnic Beach, Palfrey Island, Great Barrier Reef; paratype, female, 4.9 mm, AM P79816 (SEL/LZI-5-1), Casuarina Beach. Lizard Island, Great Barrier Reef.