Lembos quadrispinosus, 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 : 466-470

Lembos quadrispinosus sp. nov.

( Figures 11–13 )

Type material. Holotype, male (4.69 mm, drawn), PROTRINDADE, Trindade Island , off Espírito Santo, Brazil, Enseada dos Portugueses ( SECON), 10.2 m depth, 20°30’20.9”S – 29°18’43.7”W, JB Mendonça coll., 22.xi.2024, MZUSP 46919 .

Type locality. Enseada dos Portugueses, 20°30’20.9”S – 29°18’43.7”W, 10.2 m, Trindade Island , off Espírito Santo, Brazil .

Distribution. So far only known from Trindade Island, 10.2 m.

Etymology. From the Latin words “quattuor” (four) and “spina” (spine), in reference to the presence of four strong and acute sternal spines on pereonites 2-5.

Diagnosis

Rostrum short, intrantennal process absent. Pereon without pigmentation in alcohol. Pereonites 2-5 ventral margin with strong, subacute and recurved forward spines. Gnathopod 1 poorly setose, carpus robust, slightly shorter than propodus (0.9x); propodus ovate, 1.5x longer than wide, palm acute, sinuous, defined by a short spine and a robust seta. Gnathopod 2, basis with anterodistal angle produced into a blunt spine; carpus and propodus with anterior and posterior margins densely setose; carpus longer than propodus (1.8x); propodus subrectangular, 1.4x longer than wide, palm acute, defined by robust seta. Uropod 1 rami subequal in length, peduncle with interramal spine about 1/2 of rami length. Uropod 2 outer ramus shorter than inner ramus, peduncle with interramal spine 2/3 of outer ramus length. Uropod 3 rami longer than peduncle.

Description. Based on holotype.

Head. Rostrum short, intrantennal process absent. Lateral cephalic lobes subquadrate; eyes of medium size, dark.Antennae missing. Maxilla 2 outer and inner plates subequal; inner plate with oblique setal row. Mandible palp article 1 0.6x of article 2 length, lacking setae; article 2 with long setae on inner margin; article 3 longer than article 2 (1.8x), outer and inner margins with long setae; left mandibular molar with primary plate falcate.

Pereon. Lacking color pigmentation in dorsum of head, pereonites, and pleonites. Segments 2-5 with strong, subacute and recurved forward spines. Gnathopod 1 coxa subrectangular, 1.4x wider than deep; basis to propodus lacking tubercles; basis moderately stout, about 1.8x longer than broad; merus with short setae on posterodistal angle; carpus 1.3x longer than broad, posterior margin with a broad and rounded process, bearing long setae; propodus ovate, subequal in length to carpus, 1.8x longer than broad, palm acute, sinuous, with long setae; palmar corner defined by a short acute process, bearing a robust seta; dactylus elongate, inner margin serrate, fitting palm. Gnathopod 2 coxa subrectangular, 1.3x wider than deep; basis elongate, slender, 2.7x longer than broad, anterior margin weakly concave, posterior margin convex, anterodistal angle produced into a blunt spine; carpus elongate, 2.2x longer than broad, anterior margin clothed with long setae; propodus 1.5x longer than wide, anterior margin clothed with long setae; palm acute, finely serrate, defined by a robust seta; dactylus curved, inner margin serrate, fitting palm. Pereopods 3-7 missing.

Pleon. Epimera 1-3 posterior margin rounded. Uropod 1 peduncle 0.8x outer ramus length, with a robust seta distally; interramal spine robust, 0.6x of peduncle length; rami subequal in length; outer ramus with four marginal robust setae, apically with four robust setae; inner ramus with five robust setae, apically with four robust setae. Uropod 2 peduncle subequal in length to outer ramus, with one robust seta distally; interramal spine robust, 0.6x length of peduncle; inner ramus longer than outer ramus (1.2x), with six marginal robust setae, apically with four robust setae; outer ramus with four marginal robust setae, apically with three robust setae. Uropod 3 peduncle 1.8x longer than broad; rami subequal to each other and moderately long, 1.6x longer than peduncle; inner ramus margin with two robust setae and a tuft of slender marginal setae, apically with five slender setae; outer ramus with a tuft of slender marginal setae, apically with five slender setae. Telson almost as long as wide, with a pair of short plumose setae on lateral margin and two pairs of long setae and one short and plumose seta on dorsal crest, distally rounded.

Female unknown.

Remarks. Lembos is represented in Brazilian waters by only two species so far, L. conicurvae ( Oliveira, 1955) , described from Guanabara Bay, Rio de Janeiro, and L. hypacanthus K.H. Barnard, 1916 , originally described from Sea Point, near Cape Town, South Africa, and much later recorded from Brazil ( Oliveira 1955; Wakabara et al. 1991; Valério-Berardo & Miyagi 2000). Lembos quadrispinosus sp. nov. can be separated from L. conicurvae by the shape of the propodus palm of gnathopod 1, which is sinuous and lacks the characteristic excavation near the palmar corner in addition of having the palmar corner poorly developed, while the latter species has wide propodal palm characteristically excavated near the palmar corner, which is defined by two strongly developed spines.

Lembos quadrispinosus sp. nov. clearly differs from L. hypacanthus sensu Valério-Berardo & Miyagi (2000) in several aspects (characters of L. hypacanthus within brackets): gnathopod 1 with carpus and propodus weakly setose (vs. carpus and propodus densely setose); palm of the propodus of gnathopod 1 lacking any process and palmar corner defined by a short spine and a short robust seta (vs. palm with a strong midway triangular spine and defined by a large robust seta, Fig. 14 aG1); gnathopod 2 subchelate (vs. gnathopod 2 simple), anterodistal angle of the basis produced into a blunt spine and lacking a robust seta (vs. not produced and with a robust seta Fig. 14 aG2), anterior margin of carpus densely setose (vs. anterior margin of carpus weakly setose), pereonites 2-5 with a ventral strong, subacute and recurved forward spines (vs. perenoite 2 with a ventral subacute spine, pereonites 3-4 with a blunt ventral process) and outer ramus of uropod 3 with long and slender setae on lateral margin (vs. outer ramus of uropod 3 with apical slender setae only). We notice here that in the original description, the basis of the gnathopod 2 has a strong recurved spine at the anterolateral angle ( Fig. 14 bG2), however, this character is absent in the material described from Brazilian waters by Valério-Berardo & Miyagi (2000). Unfortunately, this material is presumed lost and we could not examine it to verify if it is or not a different species either from L. quadrispinosus sp. nov. or L. hypacanthus .

Lembos quadrispinosus sp. nov. superficially resembles L. barbatus Mateus & Mateus, 1967 , described from Praia Pequena, Principe Island (West Africa), based on an incomplete specimen. The original description of L. barbatus is generally short and only the carpus and propodus of gnathopods 1 and 2 were illustrated (actually L. barbatus may well belong in the genus Autonoe Bruzelius 1859 instead of Lembos, A. Myers pers. comm.). Yet, both species concur in having the propodus of the gnathopod 1 subovate, with palm acute and defined by a spine and a robust seta, in addition of having the gnathopod 2 with carpus and propodus densely setose. The new species can be distinguished from L. barbatus (characters within brackets) in that the gnathopod 1 propodus palm is sinuous, with a poorly developed spine at palmar corner (vs. palm with a rectangular process and a strongly developed spine at the palmar corner); sternal ventral spines on pereonites 2-5 subequal in size (vs. ventral spine on pereonite 2 longer than the remaining ones from pereonites 3-5).

Although based on a single specimen, the unique combination of characters in the Trindade Island specimen clearly suggest it is new.

Figures

FIGURE 11. Lembos quadrispinosus sp. nov. Holotype, male (4.69 mm), Habitus and Mandible, Trindade Island, off Espírito Santo, Brazil, 10.2 m depth, 20°30’20.9”S–29°18’43.7”W, JB Mendonça coll., 22.xi.2024, MZUSP 46919. Abbreviations: Hb, habitus; Md, mandible. Scale bars = 0.5 for habitus and 0.1 mm for Mandible.

FIGURE 12. Lembos quadrispinosus sp. nov. Holotype, male (4.69 mm), gnathopods 1-2, Trindade Island, off Espírito Santo, Brazil, 10.2 m depth, 20°30’20.9”S–29°18’43.7”W, JB Mendonça coll., 22.xi.2024, MZUSP 46919. Abbreviations: G, gnathopod. Scale bars = 0.1 mm.

FIGURE 13. Lembos quadrispinosus sp. nov. Holotype, male (4.69 mm), Thoracic sternal spines, uropods 1-3, telson, Trindade Island, off Espírito Santo, Brazil, 10.2 m depth, 20°30’20.9”S–29°18’43.7”W, JB Mendonça coll., 22.xi.2024, MZUSP 46919. Abbreviations: Pr, pereonite; T, telson; Ur, uropod. Scale bars = 0.1 mm.

FIGURE 14. Lembos hypacanthus K.H. Barnard, 1916. aG1, male gnathopod 1, aG2, male gnathopod 2, redrawn from Barnard (1916: Plate XXVIII, fig. 5-6), with some setae omitted to highlight the strong, mid-palm triangular spine on propodus of G1. bG1, male gnathopod 1, bG2, male gnathopod 2, redrawn from Valério-Berardo & Miyagi (2000: fig. 87-88), with some setae omitted to highlight the mid-palm triangular spine on propodus of G1.