Leucothoe mucifibrosa, 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 : 254-258

Leucothoe mucifibrosa sp. nov.

( Figs. 1–4 )

http://zoobank.org/ urn:lsid:zoobank.org:act:EFC92B75-226A-4F47-95A1-F4D4D6675603

Type locality: Twin Keys, Belize, 16° 50.224’ N, 88° 06.163’ W, 6m depth, from the sponge Haliclona mucifibrosa Weerdt, Rutzler, and Smith, 1991 ; 26 August 2006, James Darwin Thomas collector.

Holotype: YPM IZ.111030, male, 3.14 mm

Paratypes: GCRL6623 , female, 3.14 mm, male, 2.64 mm

Other material examined: GCRL 6624 , 7 male, 29 female specimens; YPM IZ.111031, 6 male, 29 female specimens; same station data as type specimens .

Diagnosis: Left and right mandibles each with layered lacinia mobilis; maxilliped outer plate strongly serrate; gnathopod 1 propodus palm serrate, dactylus reduced, reaching 0.2X propodus length, basis expanded proximally; telson apical margin rounded, bare.

Description of male holotype: Head. Anterior head margin truncate, anterodistal margin subquadrate. Ventral cephalic keel slightly excavate anteriorly. Eyes oval. Antenna 1, 0.28X body length, flagellum 7-articulate, accessory flagellum minute, 1-articulate. Antenna 2, 0.25X body length, 0.88X length of antenna 1, flagellum 5-articulate. Mandibular palp articles ratios 1–3, 1.0: 2.36:2.09, article 2 with 1 marginal and 1–2 distal setae, article 3 with 2–3 terminal setae, incisors strongly dentate, each lacinia mobilis strongly toothed, layered; left mandible with 8 raker spines, right mandible with 9 raker spines. Upper lip asymmetrically lobate, anterior margin weakly 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 4 robust distal setae and 2 slender medial marginal setae. Maxilla 2 inner plate with 3 distal setae, one mediofacial seta, and several slender marginal setae; outer plate with 2 distal and several slender marginal setae. Maxilliped inner plates, distal margin rounded with deep V-shaped indentation, setose; outer plate inner margin strongly tuberculate, reaching 0.5X along palp article 1; palp dactyl subequal in length with article 3, distally acute.

Pereon. Coxae 1–4 relative widths 1.0: 1.5: 1.1: 1.9. Gnathopod 1 coxa anterior margin serrate, anterodistal margin slightly produced, rounded, distal margin straight, serrate, posterior margin excavate; basis distally inflated, anterior and posterior margins bare; ischium bare; carpus straight, distal length 7X width, proximal margin smooth; propodus straight, palm serrate with several small medial setae; dactylus smooth, reaching 0.2X propodus length. Gnathopod 2 coxa equally as broad as long, wider than coxa 3, smooth, bare, anterior margin rounded, anterodistally rounded, distal and posterior margins straight; basis straight, anterior margin with 2–3 medium setae, posterior margin bare; carpus reaching 0.5X propodus length, curved, distally tapered, anterior margin serrate; propodus with single mediofacial setal row 0.84X propodus length, posterior margin smooth, palm convex, serrate with several small medial setae and one submarginal setal row; dactylus curved, reaching 0.4X propodus length, proximal margin smooth, bare, anterior margin distally tapered, apically rounded. Pereopod 3 coxa length 0.69X width, anterodistal corner overriding distal face of coxa 2, serrate, anterior and posterior margins straight, distal margin rounded. Pereopod 4 coxa anterior margin straight, serrate, distal margin rounded, posterior margin tapered. Pereopods 5–7 coxae, facial setae absent. Pereopods 5–7 bases width length ratios 1: 1.53, 1: 1.38, 1: 1.3, posterior margins serrate, with few fine setae, pereopod 7 basis posterior margin rounded.

Pleon. Epimera 1–3 bare, epimeron 3 posteroventral corner subquadrate. Uropods 1–3 relative lengths 1.0: 0.63: 0.94. Uropod 1 peduncle subequal in length with inner ramus, outer ramus 0.82X inner ramus length. Uropod 2 peduncle subequal in length with inner ramus, outer ramus 0.67X inner ramus length, Uropod 3 peduncle 1.2X inner ramus length, outer ramus subequal in length with inner ramus. Uropods 1–3 inner and outer rami distal margins with several robust setae. Telson length 2.5X width, apical margin rounded, bare; with 2 plumose facial setae.

Female sexually dimorphic characters: Like male in all aspects except gnathopod 2 carpus anterior margin smooth.

Etymology: Referring to the sponge host of this species.

Color: Live specimens are white.

Geographical distribution: Known only from Belize

Ecology: Collected from interior cavities of the sponge Haliclona mucifibrosa . This sponge is tubular in form and creates a network of mucous strands.

Remarks: Leucothoe mucifibrosa sp. nov. shares the short gnathopod 1 dactylus and the elongate maxilliped outer plate with members of the ‘ Paraleucothoe group’ [ Leucothoe enko White & Reimer 2012c , Leucothoe kebukai White & Reimer 2012c , Leucothoe nagatai Ishimaru, 1985 , Leucothoe obuchii White & Reimer 2012a , Leucothoe panjang White & Thomas, 2022 , Leucothoe toribe White & Reimer 2012b , Leucothoe wheromura White & Thomas, 2022 ]. Of these species, L. mucifibrosa sp. nov. shares an apically rounded telson with L. enko ; the layered lacinia mobiles on the mandibles with L. nagatai , L. panjang , and L. wheromura ; and a serrate inner margin on outer plate of maxilliped with L. panjang . The new species, however, differs from all mentioned species in having a serrate gnathopod 1 propodus palm (smooth in all species except dentate in L. enko ). The only other species with a short gnathopod 1 dactylus documented from Belize is Leucothoe flammosa Thomas & Klebba, 2007 , which differs from the new species in having gnathopod 1 carpus with setose midposterior and posterior margins, lacking the accessory flagellum on antenna 1 and the layered lacinia mobiles.

Figures

FIGURE 1. Leucothoe mucifibrosa sp. nov. male holotype, 3.14 mm.A Antenna 1 enlarged; B Habitus; C Antenna 2 enlarged; D Gnathopod 1 medial; E Gnathopod 1 propodus enlarged; F Gnathopod 1 carpus enlarged. Scale bars: 1 = 0.1mm (A), 2 = 1 mm (B), 3 = 0.5 mm (D), 4 = 0.1 mm (E,F).

FIGURE 2. Leucothoe mucifibrosa sp. nov. male holotype, 3.14 mm. A Right mandible; B Left mandible; C Maxilla 2; D Upper lip; E Maxilla 1; F Maxilla 1 outer plate enlarged; G Lower lip; H Maxilliped. Scale bars: 1 = 0.1 mm (A,B), 2 = 0.1 mm (E), 3 = 0.1 mm (F–H).

FIGURE 3. Leucothoe mucifibrosa sp. nov. female paratype, 3.44 mm. A Gnathopod 1 medial; B Gnathopod 2 medial. Leucothoe mucifibrosa sp. nov. male holotype, 3.14 mm. C Telson; D Gnathopod 2 medial; E Uropod 1; F Uropod 2; G Uropod 3. Scale bars: 1 = 0.5mm (A,B), 2 = 0.5 mm (D), 3 = 0.1 mm (C), 4 = 0.5 mm (E–G).

FIGURE 4. Leucothoe mucifibrosa sp. nov. male holotype, 3.14 mm. A Peropod 5; B Pereopod 6; C Pereopod 7. Scale bar: 1 = 1 mm (A–C).