Ampelisca milenae, Marinho & Souza-Filho, 2025

Ampelisca milenae sp. nov.

( Figures 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Type material. Holotype: female (5.2 mm, dissected and drawn, 2 slides), Bpot-Talude MT54-R3 , (04º37.25’S, 36º44.56’W), Brazil, Potiguar Basin , 168 m, in silty-sand bottom, 15.xi.2009, MOUFPE 21621 View Materials . GoogleMaps

Paratypes: 115 females and 3 males (1 male, 4.5 mm dissected and drawn, 1 slide), Bpot-Talude MT54-R1, (04º37.22’S, 36º44.53’W), Potiguar Basin , Brazil, 186 m, in silty-sand, 10.xi.2009, MOUFPE 15988 View Materials GoogleMaps . 189 females and 1 male, Bpot-Talude MT54-R3, (04º37.25’S, 36º44.56’W), Brazil, Potiguar Basin , 168 m, in silty-sand bottom, 15.xi.2009, MOUFPE 16008 View Materials GoogleMaps .

Etymology: Named in honor of the first author’s friend, Milena Morais Paiva, who was loved and a talented biology student, she passed away too young during the COVID-19 pandemic while undergoing cancer treatment.

Diagnosis: Head with anteroventral margin oblique. Antenna 1 exceeding distal part of peduncle of antenna 2. Antenna 2 longer than body length. Coxa 1 posteroventral corner with short notch forming a spine. Pereopod 5 dactylus with two accessory cusps. Pereopod 6 dactylus with three accessory cusps. Pereopod 7 basis posterior margin obliquely rounded without crenulate structure; ischium shorter than merus; merus posterodistal lobe reaching to middle of carpus and with four slender and long setae on posterior margin; carpus anterior margin with a little notch bearing one robust setae, posterodistal lobe with two robust setae bearing one accessory setae and one long and plumose seta; propodus barely longer than carpus (1.5x), length 2x breadth; dactylus slightly smaller than propodus. Epimeral plate 1 posteroventral corner rounded and with 2 short simple setae; epimeral plate 3 posteroventral corner without spine. Urosomite 1 with a weakly developed rounded process on posterodorsal margin. Uropod 2 inner and outer rami with marginal robust setae and lacking subapical seta. Uropod 3 rami lanceolate, longer than peduncle and poorly setose. Telson deeply cleft, inner angle of apex slightly produced, each lobe with one apical robust seta and 1 simple seta, one dorsal robust setae and one lateral simple seta.

Description (based on holotype, female, 5.2 mm). Head ( Figure 1 View FIGURE 1 ) longer than wide (1.3 X), equal to pereonites 1–3 combined, anteroventral margin oblique. Antenna 1 ( Figure 1 View FIGURE 1 ) longer than antenna 2 peduncle, peduncular article 2 2.0 X longer than article 1 and 2.1 X longer than article 3; flagellum with 18 articles, 3.0 X longer than peduncle. Antenna 2 ( Figure 1 View FIGURE 1 ) longer than body length, peduncular article 4 longer than peduncular article 5 (1.1 X); flagellum with 31 articles, longer than peduncle. Mandible ( Figure 2 View FIGURE 2 ) with 8 accessory setal rows; palp article 2 not inflated, both inner margins with long simple setae, article 3 0.8 X of article 2, with setae on outer, inner, and distal margins. Upper lip ( Figure 2 View FIGURE 2 ) wider than longer, entire distally. Lower lip ( Figure 2 View FIGURE 2 ) bilobed, inner plate half height of outer, lined apically with short setae; outer lobe with apical row of short setae and one subapical row setae. Maxilla 1 ( Figure 2 View FIGURE 2 ) inner plate with 2 apical simple setae; outer plate with 10 serrate robust setae,dorsal margin with 4 long slender setae; palp article 2 provided with 4 distal cusps accompanied by 4 apical robust setae with 1 longer and serrate, 4 subapical setae, 2 of them composed with some plumose setae. Maxilla 2 ( Figure 2 View FIGURE 2 ) inner plate slightly shorter than outer plate; inner plate with a row of long simple slender setae apically; outer plate with a row of long plumose setae apically. Maxilliped ( Figure 2 View FIGURE 2 ) inner plate rectangular distally with 2 robust setae, 4 plumose setae, and 1 long plumose seta; outer plate reaching the distal part of palp article 2, bearing 7 chisel–shaped robust setae, each one with 1 accessory; 2 apical chisel–shaped robust setae more elongated and slenderer than the first 7 robust setae; palp article 3 with article 4 inserted at the distal mid length, article 4 with a nail and 4 serrated setae subdistally. Upper lip with basic characters for the genus.

Coxae 1–4 ( Figure 3 View FIGURE 3 ) longer than broad. Coxa 1 posteroventral corner with a short notch forming a spine and distally widened. Coxae 1 and 2 with a row of plumose setae on the ventral margin. Gnathopod 1 ( Figure 3 View FIGURE 3 ) basis weakly inflated distally, with 13 short simple setae on the anterior margin, 3 plumose setae near the anterodistal angle, short simple long setae on the posterior margin, and 2 plumose setae on the posterodistal angle; ischium with 2 long setae on the posterodistal angle, posterior margin with 3 plumose and 1 simple setae; merus with long setae along the posterior margin, a group of long setae on the anterior margin; carpus 1.2 X propodus length, both articles with posterior margins with pinnate setae; dactylus curved, with 4 setae pinnate and a simple seta along the inferior margin and proximally on the dorsal margin, unguis present. Gnathopod 2 ( Figure 3 View FIGURE 3 ) basis weakly inflated distally, anterior margin lined with short and long setae, 3 plumose setae present; merus longer than ischium, with long 7 plumose setae on the posterior margin; carpus 1.6 X propodus length, anterior and posterior margins with groups of setae, distal margin with serrate setae; propodus with long simple setae on both margins and a sort of serrate setae on the posterior margin and on the lateral region; dactylus slightly curved, with 2 setae pinnate and a simple seta along the inferior margin and proximally on the dorsal margin, unguis present. Pereopod 3 ( Figure 3 View FIGURE 3 ) merus with 3 long plumose setae along both antero and posterodistal margin; carpus with 4 long plumose setae on the posterior margin; propodus with 5 long simple setae on the anterodistal margin. Pereopod 4 ( Figure 3 View FIGURE 3 ) basis with plumose setae on the anterodistal margin and long plumose and simple setae along the posterior margin; merus length 3 X breadth, heavily plumose setae on both margins; carpus with plumose setae on the posterodistal corner; propodus with long simple setae on the posterodistal corner. Pereopod 5 ( Figure 4 View FIGURE 4 ) basis subovoid, the anterior margin with 8 plumose setae; carpus 1.1X longer than propodus and produced posterodistally, anterior margin with 8 setae being 4 serrate setae, posterodistal corner with 4 robust setae, 2 simple long setae, 1 plumose setae; propodus anterior margin of the propodus with 7 simple setae, being 2 serrate, posterior margin with 2 robust setae; dactylus short, with 2 accessory spines. Pereopod 6 ( Figure 4 View FIGURE 4 ) basis subovoid, the anterior margin with 3 long plumose and 12 short simple setae; ischium with 2 short simple setae on the posterior margin; merus with 4 short simple setae on the anterior margin and 2 simple short setae on the posterior margin; carpus longer than propodus (1.3 X), the posterior margin with 3 comb of setae (1–2–4) and 2 long simple setae and 3 robust setae; propodus with a row of 7 robust setae, each one with 1 accessory plumose seta; dactylus short, with 3 accessory cups. Pereopod 7 ( Figure 5 View FIGURE 5 ) basis posterior margin obliquely rounded, reaching to the middle of merus, with a row of plumose setae; ischium shorter than merus, and with 3 short simple setae on the anterodistal corner; merus posterodistal lobe reaching to the middle of carpus, lobe margin with 4 long simple setae and 1 short simple seta, anterodistal margin corner with 1 simple setae; carpus anterior margin with a notch bearing 1 simple seta, anterodistal corner with 2 robust setae and 1 long plumose setae; propodus longer than carpus (1.5 X), length, anterodistal corner with 3 robust setae; dactylus subequal to the propodus, curved anterodistally and with 2 short simple setae on the posterior margin, almost in the apical region.

Epimeral plate 1 ( Figure 4 View FIGURE 4 ) posteroventral corner rounded, with 2 short simple setae. Epimeral plate 2 ( Figure 4 View FIGURE 4 ) posteroventral corner rounded. Epimeral plate 3 posteroventral corner smooth and subquadrate. Urosomite 1 ( Figure 4 View FIGURE 4 ) with dorsal margin slightly produced into a little hump and posteroventral corner with 2 short setae. Urosomite 2 ( Figure 4 View FIGURE 4 ) dorsal margin slightly produced into a hump. Uropod 1 ( Figure 5 View FIGURE 5 ) extending to the end of uropod 2, peduncle subequal to rami, ventral margin with two robust setae, dorsal margin with four robust setae; inner ramus with three robust setae on the first 1/2 length; outer ramus without setae. Uropod 2 ( Figure 5 View FIGURE 5 ) peduncle longer than rami, with four robust setae; inner ramus shorter than the outer ramus, with five robust setae distributed in two lines (inner and outer margins); outer ramus with four robust setae; both rami lacking subapical robust setae. Uropod 3 ( Figure 5 View FIGURE 5 ) peduncle shorter than rami, dorsal margin with two robust setae; inner ramus with five slender setae and one plumose seta, notch on the end, and 1 simple setae on this notch; outer ramus wider than the inner ramus, ventral margin with a row of 3 plumose and slender setae and 5 simple robust setae, outer facial margin with a row of short spines on distal half. Telson ( Figure 5 View FIGURE 5 ) each lobe with one dorsal robust seta, one lateral slender seta, and the apex slightly excavated bearing a robust seta and a slender seta.

Description of male (sexually dimorphic characters only)

Differs from the female by antenna 1 ( Figure 1 View FIGURE 1 ) being more setose and the presence of callynophores on antenna 2. The eyes are bigger and the head a little slender. Pereopod 7 ( Figure 5 View FIGURE 5 ) are slender than in the female; the basis posterior margin has approximately half of the plumose setae found on the female P7. Urosomite 1 ( Figure 4 View FIGURE 4 ) with a dorsal margin more produced to form a saddle-shaped structure. Uropod 3 ( Figure 5 View FIGURE 5 ) male with long plumose setae along the outer and inner rami.

Geographic distribution: Known   GoogleMaps only from the type locality, Potiguar Basin   GoogleMaps , Rio Grande do Norte, Brazil (04º37.25’S, 36º44.56’W), Brazil, Potiguar Basin, 168 m depth.

Variations: There are no significant morphological variations on the material examined here. However, we can observe two main differences between small (3.3 -4.9 mm) and larger individuals (5.0-6.0 mm): a) length of antenna 2, which can exceed about 40-90% the body length in smaller individuals, but in larger individuals it is no more than 30%; and b) in larger individuals the dorsal hump on urosomite 1 can be more developed being somewhat upturned.

Remarks: The new species is similar to A. romigi Barnard, 1954 , described originally from California, which is also recorded from Brazilian waters ( Serejo et al. 2000), by the head with ventral margin oblique, rami of uropod 2 lacking apical robust setae, rami of uropod 3 lanceolate, pereopod 7 carpus bearing a notch on anterior margin and that of merus with the posterior margin weakly lobed. However, they differ from each other as follow (characters of A. romigi in parenthesis): head equal to pereonites 1–3 combined (vs. shorter than first 3 pereonites together); antenna 1 overreaching peduncular article 5 of antenna 2 (vs. antenna 1 reaching middle of peduncular article 5 of antenna 2 on A. romigi ); coxae of gnathopod 2 and pereopod 3 without a notch on posteroventral corner (vs with a notch); urosomite 1 dorsal margin slightly produced into a hump and posteroventral corner with 2 short setae (vs. weakly saddle-shaped process on A. romigi ); and inner ramus of uropod 3 not distally uncinate (vs. uncinate).

In having the antenna 2 longer than body length A. milenae resembles A. rocasensis Souza-Filho, Souza and Valério-Berardo, 2009 and A. youngi Valério-Berardo, 2007 , nevertheless these two species is readily distinguished from A. milenae (in parenthesis) by the urosomite 1 with dorsal margin saddle-shaped (vs. weakly produced into a hump), pereopod 7 posterior margin of basis crenulate (vs. not crenulate), outer ramus of uropod 2 with a robust setae subdistally (vs. without setae), and outer ramus of uropod 3 with halfway robust setae (vs. without setae).