Leucothoe darthvaderi, Cummings & White & Thomas, 2023

Cummings, Victoria M., White, Kristine N. & Thomas, James Darwin, 2023, Two new sponge inhabiting leucothoid amphipod species from the Western Atlantic, Zootaxa 5389 (2), pp. 253-265 : 259-263

Leucothoe darthvaderi sp. nov.

( Figs. 5–8 )

Leucothoe sp. F : LeCroy, 2011, p. 639, Fig. 522. http://zoobank.org/ urn:lsid:zoobank.org:act:D4F4B492-25F0-4394-B3B3-BF99CE15141A

Type locality: Mollases Key, Florida, U.S. A, from the sponge Spheciospongia vesparium ( Lamarck 1815) ; 1969, Richard Heard collector.

Holotype: YPM IZ.111032, male, 7.85 mm.

Paratype: GCRL 6625 , female, 7.7 mm .

Other material examined: GCRL 6626 , 11 male, 33 female specimens, same station data as type specimens . YPM IZ.111033, 38 male, 39 female specimens, Channel No. 5, Upper Keys , Florida, U.S. A, 24.823720° N, 80.765323° W, 2 m depth, from the sponge Cliona varians ( Duchassaing & Michelotti, 1864) ; 12 April 2012, James Darwin Thomas collector .

Diagnosis: Mandibular palp article 2 with 13–15 marginal setae; male gnathopod 2 basis anterior margin with large serrate tubercles and short setae, carpus apically subtruncate; pereopods 5–7 bases relatively expanded, each propodus anterior margin with continuous setae, distal setae longer, pereopod 7 basis posteriorly tapered. Female gnathopod 1 basis posterior margin with several long distal setae.

Description of male holotype: Head.Anterior head margin slightly rounded, anterodistal margin evenly rounded. Ventral cephalic keel convex anteriorly with subacute anteroventral corner. Eyes reniform. Antenna 1 0.32X body length, flagellum 11-articulate, accessory flagellum minute, 1-articulate. Antenna 2 0.29X body length, 0.9X length of antenna 1, flagellum 9–articulate. Mandibular palp ratio of articles 1–3 1.0:2.4:1.0, article 2 with 13–15 marginal setae, article 3 with 2 terminal setae, left mandible incisor strongly dentate, lacinia mobilis strongly toothed, with 15 raker spines, right mandible incisor strongly dentate, lacinia mobilis weakly toothed, with 15 raker spines. Upper lip asymmetrically lobate, anterior margin strongly setose. Lower lip inner lobes fused, setose; outer lobes with large gape, anterior margins setose. Maxilla 1 palp 2-articulate, with 3 distal setae; outer plate with 6 distal robust setae and several slender marginal setae. Maxilla 2 inner plate with 7 thick distal setae, inner margin with several fine setae; outer plate with 2 thick distal and several slender marginal setae. Maxilliped inner plates distal margin rounded with v-shaped indentation, with few large setae; outer plate inner margin smooth, reaching 0.3X palp article 1; palp article 4 0.73X length of article 3, distally acute.

Pereon. Coxae 1–4 relative widths 1.0: 1.5: 1.0: 1.7. Gnathopod 1 coxa anterodistal margin strongly produced, rounded, serrate, bare, distal margin straight, serrate, posterior margin excavate; basis proximally inflated, anterior margin with several short setae; carpus straight, distal length 9.8X width, proximal margin smooth, lined with short setae; propodus straight, palm finely dentate with several small lateral setae; dactylus smooth, reaching 0.5X propodus length. Gnathopod 2 coxa equally as broad as long, wider than coxa 3, smooth, bare, anterior margin rounded, anterodistally rounded, distal margin straight, posterior margin slightly convex; basis straight, anterior margin lined with large tubercles and short setae, posterior margin bare; carpus 0.55X propodus length, curved, distally subtruncate, anterior margin serrate; propodus with 2 mediofacial setal rows, primary row reaching 0.57X propodus length, secondary row with one seta, posterior margin smooth, palm convex with several small medial setae and one submarginal setal row, with 2 large and several small tubercles; dactylus curved, reaching 0.50X propodus length, proximal margin smooth, bare, anterior margin distally tapered, apically acute. Pereopod 3 coxa length 1.33X width, anterodistal corner overriding distal face of coxa 2, smooth, anterior margin straight, distal margin rounded, posterior margin tapered. Pereopod 4 coxa smooth, anterior margin straight, distal margin rounded, posterior margin tapered. Pereopods 5–7 bases width length ratios 1: 1.14, 1: 1.17, 1: 1.13 posterior margins serrate, bare, each propodus anterior margin with setae distally clustered, pereopod 7 basis posterior margin tapered.

Pleon. Epimeron 1 with anteroventral tuft of setae, epimeron 2 with few marginal setae, epimeron 3 bare, posteroventral corner rounded. Uropods 1–3 relative lengths 1.0: 0.69: 0.84. Uropod 1 peduncle 0.90X length of inner ramus, outer ramus 0.91 X length of inner ramus. Uropod 2 peduncle 0.59X length of inner ramus, outer ramus 0.64X inner ramus length, uropod 3 peduncle 1.08X inner ramus length, outer ramus 0.96X length of inner ramus. Uropods 1–3, inner and outer rami lined with robust setae. Telson length 2.71X width, apical margin tridentate with 2 apical setae.

Female sexually dimorphic characters: Similar to male in all aspects except for the following: gnathopod 1 basis anterior margin with longer setae and posterodistal margin with several long distal setae; gnathopod 2 basis anterior margin smooth with several long distal setae.

Etymology: Named for Darth Vader from the Star Wars movie series about the takeover of the Imperial rebel army, in reference to the rapid appearance and colonization of L. darthvaderi sp. nov. in the host sponge Cliona varians .

Color: Live specimens have a distinct translucent white color.

Geographical distribution: Known from the Florida Keys and southern Gulf of Mexico

Ecology: Leucothoe darthvaderi sp. nov. is commonly found in the sponge Cliona varians . In 1983, the third author collected a single specimen of L. darthvaderi sp. nov. from the branchial chamber of the solitary tunicate Phallusia nigra Savigny, 1816 from Sawyer Key in the Florida Keys.

Remarks: Leucothoe darthvaderi sp. nov. is part of the Leucothoe spincarpa species complex, with a rounded head and long gnathopod 1 dactylus. It is similar to Leucothoe tunica White, 2019 collected from Florida in overall appearance, including a long gnathopod 1 dactylus and tapered posterior margin on pereopod 7. The new species differs from every known leucothoid species in having the gnathopod 2 basis anterior margin lined with large tubercles. The new species shares the long setae on posterodistal margin of female gnathopod 1 basis and the heavily setose mandibular palp article 2 with Leucothoe ubouhu Thomas & Klebba, 2007 , but differs in having an accessory flagellum on antenna 1 (lacking in L. ubouhu ), rounded head anterodistal head margin (angular in L. ubouhu ), pereopod 7 basis posteriorly tapered (rounded in L. ubouhu ), and the tuft of setae on epimeron 1 anteroventral margin (lacking in L. ubouhu ).

Figures

FIGURE 5. Leucothoe darthvaderi sp. nov. male holotype, 7.85 mm. A habitus; B Antenna 1 enlarged; C Antenna 1 accessory flagellum; D Antenna 2 enlarged; E Uropod 3; F Uropod 1; G Uropod 2; H Gnahopod 2 medial; I Gnahopod 2 basis enlarged Scale bars: 1 = 1 mm (A), 2 = 0.5 mm (B,D), 3 = 0.5 mm (E–G), 4 = 0.5 mm (H), 5 = 0.5 mm (I).

FIGURE 6. Leucothoe darthvaderi sp. nov. male holotype, 7.85 mm. A Gnathopod 1 medial; B Gnathopod 1 propodus enlarged; C Gnathopod 1 carpus enlarged; D Maxilla 2; E Left mandible; F Right mandible; G Maxilliped; H Maxilla 1; I Maxilla 1 outer plate enlarged. Scale bars: 1 = 0.5 mm (A), 2 = 0.5 mm (D–H).

FIGURE 7. Leucothoe darthvaderi sp. nov. female paratype, 7.7 mm. A Gnathopod 1 medial; B Gnathopod 2 medial. Leucothoe sp. F sp. nov. male holotype, 7.85 mm. C Pereopod 5; D Pereopod 6; E Telson; F Telson apex enlarged; G Lower lip; H Upper lip. Scale bars: 1 = 0.5 mm (A–D), 2 = 0.5 mm (E), 3 = 0.5 mm (G,H).

FIGURE 8. Leucothoe darthvaderi sp. nov. male holotype, 7.85 mm. A Peropod 5; B Pereopod 6; C Pereopod 7. Scale bar: 1 = 1 mm (A–C).