Leucothoe pseudepidemos, Myers, A. A., 2013

Myers, A. A., 2013, Amphipoda (Crustacea) from Palau, Micronesia: Families Dexaminidae, Eusiridae, Hyalidae, Ischyroceridae, Leucothoidae and Lysianassidae, Zootaxa 3731 (3), pp. 301-323 : 308-311

Leucothoe pseudepidemos sp. nov.

( Figs 8 , 9 )

Type material. Holotype female, 6.5 mm, (OUMNH.ZC.2002.24.097) CRRF House Reef, from unidentified ascidian, - 12 m depth; 0 7o 20.286’N, 134o 27.430’E; leg. S. DeGrave & C. Burras, 18 May 2002. Paratypes, (OUMNH.ZC.2002.24.098) 1 male, 13 immature, same data as holotype.

Other material. 1 female, 1 immature, (OUMNH.ZC.2002.24.099) Ngeritaal Pass, from Polycarpa captiosa (Sluiter) (Ascidiacea: Styelidae ), - 5 m depth; 07°19.223'N, 134°28.271'E; leg. S. De Grave & C. Burras, 20 May 2002; 1 male, 1 immature, (OUMNH.ZC.2002.24.100) Chandelier Cave, Ngerchaol Island; from Polycarpa capitosa , - 10m depth; 07°20.442'N, 134°27.039'E; leg. C. Burras & Matt, 31 May 2002; 2 male, 3 female, 6 immature, (OUMNH.ZC.2002.24.101) Soft Coral Arch, vertical wall; from Polycarpa sp. (Ascidiacea: Styelidae ), - 10m depth; 07°16.044'N, 134°22.957'E; leg. S. De Grave, 31 May 2002; 1 male, 1 immature, (OUMNH.ZC.2002.24.102) Iro Wreck, N of Ngeruktabel Island; from Cirripathes sp. ( Antipatharia ), - 25m depth; 07°17.666'N, 134°25.222'E; leg. S. De Grave & C. Burras, 1 June 2002.

Etymology. from the latin ‘pseudo’ meaning false, prefixing the name of its closest relative.

Description. Based on female holotype, 6.5 mm.

Head. Eye lobes rounded, eye of moderate size Antennae 1 and 2 subequal in length. Antenna 1 slender; peduncular articles 1 and 2 subequal in length, article 1 a little over twice breadth of article 2; article 3 short; flagellum shorter than combined length of peduncular articles 2 and 3, with 5 articles. Antenna 2 slender, article 4 longer than article 5; flagellum shorter than peduncular article 5, with 3 articles. Labrum unequally bilobed with strong acute epistome. Mandible palp three articulate in the basi-distal ratios, 2:7:2.7.

Pereon. Gnathopod 1 coxa expanded distally bearing a single long anterofacial seta; basis constricted proximally, anterior margin with 3 short setae, posterior margin bare; ischium and merus bare; carpus with long slender posterodistal spine reaching distal end of propodus; propodus parallel-sided, posterior margin minutely crenulated and with 5 facial setae; dactylus one third length of propodus. Gnathopod 2 coxa length subequal to breadth, anterior margin rounded, posterior margin weakly concave, broader than coxa 3, lacking setae; basis stout, anterior margin with about 7 short setae; carpus almost half propodus length, spoon shaped, heavily setose; propodus subovoid, inner face with oblique row of facial setae reaching two thirds length of propodus, palm oblique with four major lobes in distal third; dactylus curved, posterior margin, smooth, two thirds length of propodus. Pereopod 3 coxa longer than broad, anterior margin convex, posterior margin straight, without facial setae. Pereopod 4 coxa broad, posteroproximal margin excavate, without facial setae. Pereopod 5–7 basis a little longer than broad.

Pleon. Epimeron 1 bare, posterodistal margin truncate,. Epimeron 2 bare, posterodistal margin produced into a sharp spine. Epimeron 3 bare, posterodistal margin produced into a short, triangular spine. Uropod 1 rami subequal and subequal in length with peduncle. Uropod 2 outer ramus shorter than inner, inner ramus 1.2 × length of peduncle. Uropod 3 rami subequal and subequal in length with peduncle. Telson 3 × as long as broad, distally minutely tridentate, with two small setae.

Male (sexually dimorphic characters). Based on paratype male 6.0 mm. Gnathopod 2 propodus palm with more strongly accentuated lobes; dactylus more than two thirds length of propodus.

Remarks. This species is closest to Leucothoe epidemos White & Thomas 2009 , from the Great Barrier Reef of Australia. It differs from that species however in a number of significant ways. In L. pseudepidemos the eye is round (subreniform in L. epidemos ), the antenna are subequal (antenna 2 shorter than antenna 1 in L. epidemos ), mandibular palp article 2 is 2.5 × the length of article 3 (much less than 2 × length in L. epidemos ), and the female gnathopod 2 palm is more heavily incised in L. pseudspidemos . In addition, present material is much smaller, 6.5 mm as opposed to 12.7–14.6 mm in L. epidemos . This could suggest that present material is simply immature L. epidemos , however the well-developed gnathopod morphlogy suggests that this is not the case. Habitat. From acidians and antipatharians.

Distribution. Known only from Palau.

Figures

FIGURE 8. Leucothoe pseudepidemos sp. nov., holotype female, Palau.

FIGURE 9. Leucothoe pseudepidemos sp. nov., holotype female, paratype male, Palau.