Maera guaiao, Queiroz & Senna & Da Silva, 2025

Maera guaiao sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Material examined.

Holotype: male, 4.1 mm, dissected and illustrated, 16 m depth, with trap, 17/III/2016, Marine State Park of Laje de Santos ( 24º19’13” S, 46º10’49” W), São Paulo State, Brazil ( UERJ 2301 ) GoogleMaps . Paratypes: 1 male, 4 mm, same collection data as the holotype ( UERJ 2300 ) GoogleMaps ; 1 female, 4 mm, same collection data as the holotype ( UERJ 2368 ) GoogleMaps .

Diagnosis.

Gnathopod 1, coxa, anteroventral projection acute; propodus palm serrated; dactylus apical nail present. Gnathopod 2, basis, anterodistal corner produced into a round lobe forward; propodus palm defined by a blunt spine, bearing two triangular processes near the dactylus articulation and a slightly concave and smooth distal half margin, with some slender and robust setae; dactylus, outer margin bearing 14 slender setae. Pereopods 5–7, basis posterodistal lobe round. Pereopod 5, dactylus apical nail bearing 1 subapical posterior spine. Pereopods 6–7, dactylus apical nail bearing 2 subapical posterior spines. Telson 80% cleft of its length.

Description of male. Based on holotype (UERJ 2300) and male paratype (UERJ 2301).

Head, slightly deeper than long. Lateral cephalic lobe round. Eyes, irregular shape. Antenna 1 missing. Antenna 2, peduncle, article 4 about 1.4× longer than article 5; flagellum 8-articulate. Upper lip with two anterior setose lobes. Mandible, incisor tri-dentate; lacinia mobilis apically multi-cuspidate; accessory setal row with six curved plumose setae; palp, distal margin of article 1 with acute projection, palp article length ratio 1:2.3:2.1. Maxilla 1, inner plate bearing three long plumose apical setae, inner and outer margins setose; outer plate distal margin bearing five bifid robust setae and one multicuspidate robust setae at mediodistal corner; palp 2-articulate, article 2 distally setose. Maxilla 2, outer plater about 1.5× wider than inner plate. Maxilliped, inner plate subrectangular, bearing one curved multi-cuspidate robust setae mediodistally, distal margin setose; outer plate ovoid, about 1.5× longer than inner plate, bearing plumose setae increasing in length distally; palp 4-articulate, apical nail present.

Gnathopod 1, coxa about 1.2× deeper than long, anteroventral projection acute, anterior margin concave, naked, ventral margin smooth, anterior half slightly setose; basis subrectangular, about 2.5× longer than wide, posterior margin with 6 long simple setae; ischium about 1.5× longer than wide, bearing a transverse row of simple setae; merus subquadrate, distal margin with a dense row of simple and pectinate setae; carpus twice longer than wide and 1.2× longer than propodus, anterior margin, subdistal depression present, acute anterodistal projection present, ventral margin bearing row of plumose setae, lateral face with 6 rows of pectinate setae and 2 rows of simple setae; propodus suboval, about 1.5× longer than wide, dorsally with 8 sets of slender setae, ventral margin setose, palm serrated and slightly acute; dactylus, outer margin with a plumose proximal seta, inner margin with 7 submarginal plumose setae, apical nail present. Gnathopod 2, coxa subquadrate, ventral margin smooth; basis narrow, about 2.7× longer than wide, anterior margin distal half setose, anterodistal corner produced into a round lobe forwards, posterior margin proximal half setose; ischium subtrapezoidal, about 1.2× longer than its greatest width; merus, posterodistal corner acute; carpus subtriangular, about as long as wide, posterodistal corner with rows of plumose and pectinate setae; propodus 1.6× longer than wide and 3.3× longer than carpus, palm defined by a blunt spine, bearing two triangular processes near dactylus articulation and a slightly concave and smooth distal half margin, with some slender and robust setae; dactylus stout, curved, outer margin bearing 14 slender setae, inner margin naked, apical nail absent. Pereopod 3, coxa subquadrate, ventral margin smooth and setose; basis subrectangular, about 3.2× longer than wide; merus, carpus and propodus length ratio 1:0.9:0.8; propodus, posterior margin with 5 robust setae; dactylus simple, apical nail present. Pereopod 4 similar to pereopod 3. Pereopod 5, coxa, anteroventral lobe produced, round and setose; basis slightly expanded, about 1.9× longer than wide, posterior margin weakly serrate and setose, posterodistal lobe round; merus about 3.4× longer than wide, posterior margin with 2 robust setae; carpus and propodus combined about 1.7× longer than merus; dactylus simple, apical nail present bearing 1 subapical posterior spine. Pereopod 6, coxa, anteroventral lobe weakly produced, bearing 2 setae; basis slightly expanded, about 1.7× longer than wide, posterior margin serrate, distal half setose, posterodistal lobe round; merus about 2.5× longer than wide, anterior margin with 6 clusters of setae; carpus and propodus combined about 1.7× longer than merus; dactylus simple, apical nail present bearing 2 subapical posterior spines. Pereopod 7, coxa with 1 anteroventral seta; basis slightly expanded, about 1.6× longer than wide, posterior margin distally serrate, posterodistal lobe round; merus about 2.2× longer than wide, anterior margin with 4 clusters of setae; carpus and propodus combined about 2.1× longer than merus; dactylus simple, apical nail bearing 2 subapical posterior spines.

Epimeral plate 1, ventral margin with 2 setae, posterior margin smooth and naked, posteroventral corner subacute. Epimeral plate 2, ventral margin with 4 setae, posterior margin smooth and naked, posteroventral corner subacute. Epimeral plate 3, ventral margin with 4 setae, posterior margin slightly sinuous, with 2 distal small setae, posteroventral corner slightly produced and acute. Pleopod 1, peduncle about 5× longer than wide, distomesial corner bearing 2 coupling hooks, rami multiarticulate and setose. Pleopod 2, peduncle about 4.8× longer than wide, distomesial corner bearing 2 coupling hooks, rami multiarticulate and setose. Pleopod 3, peduncle about 3.5× longer than wide, distomesial corner bearing 2 coupling hooks, rami multiarticulate and setose. Uropod 1, peduncle 3.8× longer than wide, dorsomesial margin bearing 5 robust setae, dorsolateral margin bearing 6 robust setae, basofacial seta present; rami subequal in length, about 0.8× as long as peduncle, both dorsally and apically bearing robust setae. Uropod 2, peduncle 1.7× longer than wide, dorsolateral margin bearing 4 robust setae, outer ramus 1.2× longer than peduncle, inner ramus slightly longer than outer, both rami dorsally and apically bearing robust setae. Uropod 3 missing. Telson deeply cleft (80% of telson length), each lobe apically bicuspidate, bearing 1 subapical and 2 lateral robust setae.

Additionally, the different types of setae present in the new species described here are illustrated ( Fig. 4 View FIGURE 4 ) and their distribution along the body of the specimen is presented in Table 1.

Sexual dimorphic characters . Based on female paratype ( UERJ 2368 ) .

Antenna 2, peduncle, article 4 about 1.3× longer than article 5; flagellum 7-articulate. Gnathopod 2, propodus 1.6× longer than wide and 2.6× longer than carpus, palm defined by a couple of robust setae and a small acute spine, weakly serrate and bearing a row of robust setae; dactylus stout, curved, outer margin bearing 9 slender setae, inner margin naked, apical nail absent.

Etymology.

The specific epithet guaiao , used in apposition, derives from the name “Guaiaó”, which was the indigenous name of the São Vicente Island, which currently covers the cities of Santos and São Vicente, in the State of São Paulo.

Type-locality.

Marine State Park of Laje de Santos ( 24º19’13” S, 46º10’49” W) GoogleMaps , São Paulo State, Brazil .

Distribution.

The species is known only from the type locality.

Remarks.

Among all the species of the genus Maer a, only 3 species do not carry spines or robust setae defining palm of gnathopod 2. Maera lucinae , M. pachytelson and M. guaiao sp. nov. have palm defined only by palmar corner. Maera guaiao sp. nov. differs from the other two species in the following characteristics (characters in M. lucinae and M. pachytelson , respectively, in parentheses): eyes irregular (reniform; oval); antenna 2, flagellum 8-articulate (5-, 12-articulate); pereopods 5–7, apical nail with 1–2 subapical spines (both smooth); telson, each lateral margin with 2 robust setae (both without robust setae).

Additionally, M. guaiao sp. nov. shares a subdistal depression present on the anterior margin of the carpus of gnathopod 1 with a group of 5 other species: M. edwardsi ; M. grossimana ; M. hirondellei ; M. irregularis ; and M. lucinae . Maera guaiao sp. nov. presents antenna 2 flagellum 8-articulate, as well as M. edwardsi and M. hirondellei , but can be distinguished from these two species by the following (characters in M. edwardsi and M. hirondellei , respectively, in parentheses): eyes irregular (absent; reniform); gnathopod 2, propodus palm defined by palmar corner (both defined by 2 spines); pereopod 6, basis about 1.7× longer than wide (2.2×; 2×); pereopod 7, carpus and propodus combined about 2.1× longer than merus (both 1.8×). On the other hand, M. grossimana and M. irregularis presents antenna 2 flagellum 10- and 6-articulate, respectively. Maera grossimana can be further distinguished from Maera guaiao sp. nov. by the following (characters in M. grossimana in parentheses): gnathopod 1, dactylus apical nail present (absent); gnathopod 2, propodus palm defined by palmar corner (defined by 2 spines); pereopods 5–7, basis posterodistal lobe present (absent). Among these 6 species, only M. irregularis has coxa 1 with a rounded anteroventral projection, while all the others, including the new species described here, have a sharply projecting coxa.