Leucothoe flammosa, Thomas, James Darwin & Klebba, Kristine N., 2007

Thomas, James Darwin & Klebba, Kristine N., 2007, New species and host associations of commensal leucothoid amphipods from coral reefs in Florida and Belize (Crustacea: Amphipoda), Zootaxa 1494, pp. 1-44 : 10-15

Leucothoe flammosa n.sp.

Figures 4–6 ; 7c–d

Leucothoe spinicarpa: Ortiz, 1975:8 .

Holotype. Male “A,” 5.44 mm, YPM 38643: Sta.— 26Jun01; Key West Florida, U.S.A.; N 24º33’32.0” x W 81º48’35.14”; patch reef, in branchial chamber of the Rough File Clam, Lima scabra , 1–3m; J.D. Thomas and K.N. Klebba, collectors.

Paratypes. Female “B,” 4.30 mm, YPM 38644: Sta.— 26Jun01; Key West, Florida, U.S.A.; N 24º33’32.0” x W 81º48’35.14”; patch reef, in branchial chamber of the Rough File Clam, Lima scabra , 1– 3m; J.D. Thomas and K.N. Klebba, collectors.

Other material examined. YPM 38645: JDT Bel03–7a— 4Mar03; Co Cat Cay, Pelican Cays, Belize; N 16º39.527’ x W 88º12.032’; mangrove lagoon, in Lima scabra , 3m; J.D. Thomas and K.N. Klebba, collectors.

Diagnosis. Antennae 1 and 2: shortened. Maxilliped: inner plate with numerous facial setae. Gnathopod 1: basis, anterior margin expanded proximally, with five short setae, posterior margin with five subproximal setae, carpus posterior margin with dense brush of 17 long setae; propodus robust, dactyl a short nail. Gnathopod 2: palm oblique, with numerous submarginal facial setae. Pereopods 5–7: narrow bases. Uropod 3: inner rami lacking setae.

Description of male holotype “A”. Ratios of antennae 1 and 2, 0.21 and 0.16 X body length; relative lengths of antenna 1 and 2, 1.00:0.78, flagella 4 and 3-segmented. Anterior margin of head rounded; mid-ventral keel reduced, anterior margin apically sharp, ventral margin straight. Coxae 1–4, width ratios 1.00:0.96:1.06:1.54; coxae 5–6 bilobed; coxa 7 reduced, ovate.

Upper lip asymmetrically lobate, anterior margin setose. Mandibles lacking molar; palp 3-articulate; ratio of articles 1–3, 1.00:2.56:1.22; article 2 thickened with nine anterior setae; article 3 with two apical setae; incisors serrate, anterior margin straight. Left mandible, lacinia mobilis large, toothed; 11 raker spines. Right mandible, lacinia mobilis a small flake; 11 raker spines. Lower lip, inner lobes fused; outer lobes with moderate gape, anterior margins continually setose, dense covering of facial setae. Maxilla 1, palp 2-articulate with four apical setae; outer plate with 10 spines. Maxilla 2, inner plate with few sparse marginal, two long, stout apical and 12 lateral setae; outer plate with three stout and numerous thin apical setae, facial margin sparsely setose. Maxilliped, inner and outer plates reduces; inner plate fused, apical lobes notched with numerous facial setae; outer plate anterolateral margins with numerous setae; palp 3-articulate; palp article 1 apical and apicolateral margins with approximately 10 setae; article 4 with dense covering of short, pubescent setae.

Gnathopod 1, coxa subquadrate, anteroventral margin smooth with one submarginal seta, ventral margin straight, posteroventral margin rounded; basis proximally thickened, anteroproximal margin produced, anterior margin with five short setae, posterior margin with five subproximal setae; carpal lobe, thickened, LW 2.17, anterior margin grooved with 10 short setae, lacking lateral ornamentation, midposterior margin with five short setae, posterior margin with dense brush of 17 long setae; propodus, posterior margin smooth, lateral margin with 13 short submarginal setae; dactyl reduced, nail-like, reaching 0.18 of propodus. Gnathopod 2, coxa quadrate, LW 0.76, anterior margin straight, anteroventral margin with one seta, ventral margin slightly rounded, posterior margin smooth; basis linear, anterior margin with seven widely spaced short setae, posterior margin bare; carpal lobe curved, lacking ornamentation, apical margin slightly constricted and tridentate, reaching 0.60 of propodus, medial margin setose; propodus, palm oblique, linear, produced as thin blade with short embedded setae, posterior margin with dense tuft of submarginal setae; primary mediofacial setal row reaching 0.61 of propodus, lacking secondary mediofacial row; dactyl smooth, curved, reaching 0.55 of propodus.

Leucothoe flammosa . male holotype “A,” 5.44 mm; female paratype “B,” 4.30 mm.

Pereopod 3, coxa quadrate, LW 1.16, anterior, ventral and posterior margins straight. Pereopod 4, coxa anterior margin straight, ventrally rounded, posterior margin straight. Pereopods 5–7, coxae 5–6 bilobed; coxa 7 small, ventrally convex; pereopods 5–7 bases narrow, LW, 1.33:1.22:1.55, posterior margins smooth.

Epimera 1–3, ventral setae, 1:5:1, respectively; epimera 2, ventral margin tapering anteriorly; epimera 3, posteroventral margin subquadrate with single posterior seta. Uropods 1–3, margins finely serrate; relative lengths 1.00:0.70:0.66; relative lengths of peduncles 1–3, 1.00:0.61:0.73. Uropod 1, peduncle 1.47 X rami length, with four medial and zero lateral marginal setae; outer ramus 0.94 X inner ramus; inner ramus with one medial and five lateral marginal setae; outer ramus with one medial and two lateral marginal setae. Uropod 2 shortened, peduncle 1.13 X rami length, with one medial and one lateral apical seta; outer ramus 0.80 X inner ramus; inner ramus with one medial and zero lateral marginal seta; outer ramus with zero medial and four lateral marginal setae. Uropod 3, peduncle 1.78 X rami length, lacking setae, outer ramus 0.89 X inner ramus, inner ramus with zero marginal and one apical seta, outer ramus with one apical and one subapical seta. Telson LW 2.22, apical margin tridentate bearing two apical setae.

Description of female paratype “B”. Similar to male in all aspects except gnathopod 1 basis, anterior margin straight, not expanded proximally, with a single subdistal seta, posterior margin slightly convex with five mid-marginal setae; carpus with fewer posterior setae (nine versus 17); propodus scimitar-shaped, gnathopod 2 propodus with single line of mediofacial setae.

Etymology. Latin, “ flammosa ” meaning “fiery red”, referring to the numerous protruding red mantle extensions of its bivalve host, the rough file clam, Lima scabra .

Relationship. L. flammosa is distinguished from all other Leucothoe species in having shortened antennae, bearing facial setae on the inner plate of the maxilliped, lower lip outer lobes with dense covering of facial setae, gnathopod 1 propodus with tufts of long setae on the posterior margin, and gnathopod 2 with a weak, obliquely dentate palm.

Ecology. Leucothoe flammosa has only been recorded from the mantle cavities of bivalve mollusks, where it inhabits the inner folds of the gills. In Florida it has been collected from the Rough File Clam, Lima scabra and the Eared Ark, Anadara notabilis . In Belize, L. flammosa is commonly found in Lima scabra and less frequently in other bivalves including Americardia media , Dendostrea frons , Lithophaga antillarum , Lucina pennsylvanica , and Mytilopsis leucopheata . Additional sampling in Florida waters will probably expand the list of known host associates for this species.

Prior reports of leucothoid amphipods from the mantle cavities of bivalves include Ortiz (1975) who reported “ L. spinicarpa ” from the mantle cavities of the bivalves Lima scabra and Atrina rigida (Lightfoot, 1786) in Cuban waters, and Morton (1980) who reported a probable specimen of Leucothoe from Pholadomya candida Sowerby 1823 in waters off Key West, Florida. While these reports are most likely L. flammosa , no specimens were saved for further studies. Because L. flammosa is only known from the mantle cavities of bivalves, it is likely that these reports were indeed L. flammosa .

Distribution. Western Atlantic, Belize to Florida, 1–20 meters.

Figures

FIGURE 4. Leucothoe flammosa n. sp. male holotype “ A, ” 5.44 mm; female paratype “ B, ” 4.30 mm.

FIGURE 6. Leucothoe flammosa n. sp. male holotype “ A, ” 5.44 mm.