Ampelisca milenae Marinho & Souza-Filho, 2025, sp. nov.
Creators: name: Marinho, Rômulo
name: Souza-Filho, Jesser F.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Ampeliscidae
Ampelisca
Ampelisca milenae

description: Ampelisca milenae sp. nov.
(Figures 1–5)
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.
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. 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.
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) longer than wide (1.3 X), equal to pereonites 1–3 combined, anteroventral margin oblique. Antenna 1 (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) 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) 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) wider than longer, entire distally. Lower lip (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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) posteroventral corner rounded, with 2 short simple setae. Epimeral plate 2 (Figure 4) posteroventral corner rounded. Epimeral plate 3 posteroventral corner smooth and subquadrate. Urosomite 1 (Figure 4) with dorsal margin slightly produced into a little hump and posteroventral corner with 2 short setae. Urosomite 2 (Figure 4) dorsal margin slightly produced into a hump. Uropod 1 (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) 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) 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) 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) 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) 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) with a dorsal margin more produced to form a saddle-shaped structure. Uropod 3 (Figure 5) male with long plumose setae along the outer and inner rami.
Geographic distribution: Known only from the type locality, Potiguar Basin, 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).
description: Published as part of Marinho, Rômulo & Souza-Filho, Jesser F., 2025, A new species of Ampelisca Krøyer, 1842 (Amphipoda, Ampeliscidae) from Potiguar Basin, Brazil, pp. 119-128 in Zootaxa 5618 (1) on pages 120-126, DOI: 10.11646/zootaxa.5618.1.8, http://zenodo.org/record/15217501