Latigammaropsis oliveirai, Guedes-Silva & Souza-Filho & Tavares, 2025

Guedes-Silva, Elkênita, Souza-Filho, Jesser F. & Tavares, Marcos, 2025, The Amphipoda of the remote oceanic archipelago Trindade and Martin Vaz (Brazil). II. Five new species of shallow-water aorid and photid amphipods (Senticaudata: Corophiida), Zootaxa 5659 (4), pp. 451-482 : 471-475

Latigammaropsis oliveirai sp. nov.

( Figures 15–18 )

Type material. Holotype, male (4.18 mm, dissected and drawn, 1 slide), MZUSP 46920 , PROTRINDADE, Trindade Island , off Espírito Santo, Brazil, Ponta Norte, artificial reef, 11 m, 20°29’18.7”S - 29°20’18.3”W, JB Mendonça coll., 23.vi.2016.

Paratypes: 1 female (4.11 mm, dissected and drawn, 1 slide), MZUSP 45132 ; 5 males, 15 females, MZUSP 46921 ; 1 male, 1 female, MOUFPE 22054 , same data as holotype . 1 male, MZUSP 46924 , ibidem, Ponta Norte , artificial reef, 14.2 m, 20°29’18.7”S - 29°20’18.3”W, J.B. Mendonça coll., 02.vii.2016 . 1 female, MZUSP 46922 , ibidem, Orelhas , 14.9 m, 20°29’32.3”S - 29°20’32.6”W, JB Mendonça coll., 22.vi.2012 . 1 juvenile, MZUSP 46923 , ibidem, Orelhas , 9.2 m, 20°29’40.2”S - 29°20’32.9”W, JB Mendonça coll., 01.vii.2016 .

Type locality. Ponta Norte, 20°29’18.7”S - 29°20’18.3”W, 11.3 m, Trindade Island , off Espírito Santo, Brazil .

Distribution. So far only known from Trindade Island, between 9.2 m and 14.9 m.

Etymology. This species is named in honor of Lejeune Pacheco Henriques de Oliveira (1915–1982) for his pioneer research on the Brazilian amphipods.

Diagnosis. Head anteroventral margin strongly recessed, eyes large, reniform (almost fused on the dorsal surface of head), only partially enclosed in the lateral cephalic lobe. Antenna 1 accessory flagellum with 3 articles. Sexual dimorphism weak. Gnathopod 2 poorly setose; basis 2.3x longer than wide; carpus about 1/2 of propodus length; propodus ovate, 1.9x longer than wide, palm acute setose, palmar corner with large subacute process bearing robust a seta; dactylus robust, recurved, shorter than palm. Uropod 1 interramal spine about 1/2 of outer ramus length. Uropod 3 peduncle broad, outer ramus 2-articulate, subequal to inner ramus, article 1 with single middle marginal robust setae and one robust seta distally; article 2 with two long setae distally. Telson suboval, distal margin with a subacute process.

Description. Based on holotype.

Head. Head with lateral cephalic lobes rounded, strongly produced. Eyes large, reniform (almost fused on dorsal surface of head), only partially enclosed in lateral cephalic lobe. Antenna 1 peduncle article 1 shorter than article 2 (0.6x); article 3 subequal in length to article 1; accessory flagellum 3-articulate. Lower lip inner and outer lobe pubescent apically; mandibular process well developed with lobes apically acute. Mandible incisor well developed; molar triturative; lacinia mobilis 5-dentate; accessory setal row with eight dentate setae; palp article 2 longest and setose; article 3 spatulate, heavily setose apically. Maxilla 1 inner plate with apex rounded bearing four subapically long slender setae; outer margin with setules; outer plate with eight serrate robust setae; palp 2-articulated. Maxilla 2 inner plate slenderer than outer plate, with marginal row of long slender setae and oblique row of setae on surface; outer plate rounded apically and subapically, with slender setae and lateral margin pubescent. Maxilliped inner plate with five apical long robust setae and one robust seta on inner margin; outer plate reaching 1/2 of article 2 palp, with seven robust setae on inner margin; palp 4-articulate, article 2 longest bearing long slender setae, article 3 longer than article 4, setose; article 4 conical, with one apical robust seta.

Pereon. Gnathopod 1 subchelate, coxa subquadrate, almost as long as wide, anteroventral angle rounded; ventral margin with seven short setae; basis slender, 2.3x longer than wide, with two short setae on anterior margin; carpus slightly longer than propodus (1.2x), posterior margin setose, anterodistal angle with tuft of setae; propodus broadly subovate, anterior and posterior margins sparsely setose, palm acute, finely serrate, and defined by a robust seta; dactylus falcate, overlapping palm. Gnathopod 2 subchelate, poorly setose; coxa subquadrate, almost as long as wide, ventral margin with sparse short setae; basis 2.3x longer than wide; carpus about 1/2 of propodus length, posterior margin with slender setae; propodus ovate, 1.9x longer than wide, anterior margin with four tufts of slender setae, posterior margin with five tufts of slender setae; palm acute, inclination of 37°, setose, palmar corner with large, subacute process bearing a robust seta; dactylus robust, recurved, shorter than palm. Pereopods 3-4 similar in shape, slender; basis linear, about 3x longer than wide, with few short setae; merus longer than propodus (1.2x); carpus shorter than merus (0.6x); propodus longer than carpus (1.3x); dactylus robust and falcate. Pereopod 5 coxa bilobate, anterior lobe deeper, broadly rounded; basis subovate, 1.4x longer than wide; merus longer than carpus (1.6x), posterodistal angle with a robust seta; carpus with a robust seta on posterior marginand two robust setae on posterodistal angle; propodus 3.3x longer than wide, posterior margin with two long robust setae and one short and robust seta; dactylus robust and falcate. Pereopod 6 coxa weakly bilobated, lobes subequal in length; basis 1.8x longer than wide; merus longer than carpus (1.6x), posterodistal angle with a robust seta; carpus with robust seta on posterior margin and two robust setae on posterodistal angle; propodus 6.0x longer than wide, posterior margin with four robust setae, distally with tuft of very long setae; dactylus robust and falcate. Pereopod 7 coxa subovate; basis 2.2x longer than wide; merus longer than carpus (1.3x), posterodistal angle with a slender seta; carpus with a robust seta on posterior margin and two robust setae on posterodistal angle; propodus 6.7x longer than wide, posterior margin with tuft of long setae, posterodistal angle with tuft of very long setae; dactylus robust and falcate.

Pleon. Uropod 1 peduncle longer than outer ramus (1.3x), dorsal margin with two robust setae; interramal spine acute, long, 0.4x of peduncle length; outer ramus with two robust marginal setae, distally with five robust seta; inner ramus with three robust marginal setae, distally with five robust seta. Uropod 2 peduncle subequal in length to outer ramus, outer dorsal margin with two robust setae, inner distal angle with a robust seta; outer ramus with two robust setae, two robust setae on lateral margins, apically with four robust setae; inner ramus with three robust setae on lateral margin, distally with five robust setae. Uropod 3 peduncle 1.3x longer than wide, 0.9x of outer ramus length, innerdistal angle with a robust seta; rami subequal in length; inner ramus tapering distally, lateral margin with two robust setae, two short robust setae distally; outer ramus 2-articulate, article 1 with one marginal robust seta and one robust seta subdistally; article 2 short, 0.1x of article 1 length, with two long setae distally. Telson subovate, almost as long as wide, lateral margin with five slender setae on distal quarter; dorsal crest with three robust setae, two slender on each side (in the right side one is broken); distal margin with a subacute process.

Female (sexually dimorphic characters only)

Females very similar to male, differing only in the less robust gnathopod 2.

Remarks. Two species of Latigammaropsis have been previously recorded from Brazilian waters, L. atlantica ( Stebbing, 1888) and L. togoensis ( Schellenberg, 1925) , both as Gammaropsis Liljeborg, 1855 ( Wakabara et al. 1991; Valério-Berardo & Myiagi 2000).

Latigammaropsis oliveirai sp. nov. can be distinguished from L. atlantica by a combination of characters (characters of L. atlantica in brackets): accessory flagellum 3-articulate (vs. accessory flagellum 5-articulate); propodus of female gnathopod 2 1.6x longer than wide (vs. gnathopod 2 2x longer than wide), inclination angle of palm about 37° (vs inclination angle of palm about 53°), palmar corner defined by a weakly developed, subacute spine (vs. a strong acute spine at the palmar corner); and telson with two sets of three robust setae on the dorsal crest (vs. with only one seta on each side).

Latigammaropsis oliveirai sp. nov. is readily distinguished from L. togoensis as follows (characters for L. togoensis within brackets): eyes large (vs eyes small); gnathopod 2 of male and female similar in shape (vs. gnathopod 2 propodus in male different from females), and gnathopod 2 with palmar corner defined by a subacute spine and a longer robust seta (vs. palmar corner rounded and with a short robust seta).

Latigammaropsis oliveirai sp. nov. superficially resembles L. hermes Myers, 2009 , from Lizard Island, Australia, and L. salomanensis Myers, 2014 , from the Saloman Atoll, in having lateral cephalic lobe distally rounded, reniform eyes partially within the lateral cephalic lobe, male gnathopod 2 with dactylus fitting palm, and palmar corner defined by a strong spine and a robust seta. However, the new species is easily distinguishable from both species in that the propodus of male gnathopod 2 is ovate, the inclination angle of palm of about 37°, and the inner ramus of uropod 1 is subequal to article 1 of the outer ramus (vs. in both species, propodus of male gnathopod 2 rectangular, inclination angle of palm of about 67°, inner ramus of uropod 3 shorter than article 1 of outer ramus).

Figures

FIGURE 15. Latigammaropsis oliveirai sp. nov. Holotype, male (4.18 mm), Habitus, Trindade Island, off Espírito Santo, Brazil, 11 m, 20°29’18.7”S - 29°20’18.3”W, 23.vi.2016, MZUSP 46920. Paratype female (4.11 mm), Mouthparts, same data as holotype, MZUSP 45132. Abbreviations: Hb, habitus; LL, lower lip; Md, mandible; Mx, maxilla; Mxp, maxilliped. Scale bars = 0.5 for habitus and 0.1 mm for the remains

FIGURE 16. Latigammaropsis oliveirai sp. nov. Holotype, male (4.18 mm), gnathopod 2, Trindade Island, off Espírito Santo, Brazil, 11 m, 20°29’18.7”S - 29°20’18.3”W, 23.vi.2016, MZUSP 46920. Paratype female (4.11 mm), gnathpods 1-2, same data as holotype, MZUSP 45132.Abbreviations: G, gnathopod; f, female; m, male. Scale bars = 0.1 mm. Scale bars = 0.5 for habitus and 0.1 mm for the remains.

FIGURE 17. Latigammaropsis oliveirai sp. nov. Paratype, female (4.11 mm), pereopods 3-7, Trindade Island, off Espírito Santo, Brazil, 11 m, 20°29’18.7”S - 29°20’18.3”W, 23.vi.2016, MZUSP 45132. Abbreviations: P, pereopod. Scale bars = 0.1 mm.

FIGURE 18. Latigammaropsis oliveirai sp. nov. Paratype, female (4.11 mm), Uropods 1-3 and telson, Trindade Island, off Espírito Santo, Brazil, 11 m, 20°29’18.7”S - 29°20’18.3”W, 23.vi.2016, MZUSP 45132. Abbreviations: T, telson; Ur, uropod. Scale bars = 0.1 mm.