Tectovalopsis potiguara Souza-Filho, Guedes-Silva & Andrade, 2024

Souza-Filho, Jesser F., Guedes-Silva, Elkênita & Andrade, Luiz F., 2024, Four new species and two new records of deep-sea Amphipoda (Crustacea: Peracarida) from Potiguar Basin, north-eastern Brazil, Journal of Natural History 58 (41 - 44), pp. 1615-1655 : 1624-1630

Tectovalopsis potiguara Souza-Filho, Guedes-Silva & Andrade sp. n.

( Figures 6–10 )

Material examined

Holotype female, 23 mm, Potiguar Basin , MT 71 , initial trawl coordinates 4.4405°S, 36.4308°W, final trawl coordinates 4.4905°S, 36.4026°W, Rio Grande do Norte state, Brazil, initial depth 937 m, final depth 1074 m, 5 May 2011, R / V Seward Johnson col. ( MOUFPE 20190 ).

Type locality

Slope of Rio Grande do Norte state, north-eastern Brazil, between 4.4405°S, 36.4308°W and 4.4905°S, 36.4026°W .

Diagnosis

Lateral cephalic lobe weakly truncate. Antennal sinus shallow. Left mandible incisor with 5 teeth, lacinia mobilis large and strongly toothed. Coxa 1 apically rounded, tapering distally. Gnathopods 1–2 ischium and carpus longer than propodus. Gnathopod 1 palm acute and serrate, defined by a long robust seta. Gnathopod 2 palm strongly acute and serrate, with a weakly excavated, inner margin with 3 robust setae on palmar corner. Epimeron 2 posteroventral corner as a spine, ventral margin bearing robust setae. Urosomite 1 with a dorsal spine. Urosomite 3 with 2 dorsal robust setae on each side. Telson about 80% cleft.

Description

Based on female holotype, 23 mm, MOUFPE 20190. Body as in Figure 6 . Head ( Figure 7a ) about 1.4× deeper than long. Antenna 1 ( Figure 7b ) accessory flagellum long, 8-articulate; flagellum article 1 with a dense row of callynophores. Antenna 2 ( Figure 7c ) weakly setose, peduncle article 4 slightly longer than article 5. Upper lip ( Figure 7d ) apically setose. Lower lip ( Figure 7e ) setose. Mandibles ( Figure 7f–g ) right incisor with 3 blunt teeth, lacinia mobilis small and toothed, molar weakly triturative and setulose, accessory setal row with 14 robust multicuspidate setae; palp 3-articulate, article 3 about 3.1× longer than broad, last 2/3 of mesial margin setose. Maxilla 1 ( Figure 7h ) inner plate with 15 plumose setae; outer plate apical margin with 11 robust setae, 10 being multicuspidate and 1 smooth; palp 2-articulate, article 2 with numerous short slender and robust setae apically. Maxilla 2 ( Figure 7i ) plates subequal and setose. Maxilliped ( Figure 7j ) inner plate with plumose setae, apex with 3 short robust setae; outer plate mesial margin with row of short robust setae, bearing apical plumose setae; palp article 4 about half the length of article 3, bearing a short apical nail.

Coxa 1 ( Figure 8a ) reduced, mostly covered by coxa 2. Coxa 2 ( Figure 8b ) broadening distally, with 9 setae. Coxa 4 ( Figure 9b ) posterior margin strongly excavate. Coxae 5–6 ( Figure 9c–d ) bilobate. Gnathopod 1 ( Figure 8a ) basis anterior margin with a row of long setae; ischium elongated; carpus about 1.3× longer than propodus; propodus with facial rows of setae; palm bearing 2 short robust setae near corner; dactylus reaching palmar corner, outer margin with a distal seta. Gnathopod 2 ( Figure 8b ) ischium elongated, with a posterodistal blunt projection; carpus about 1.2× longer than propodus; propodus with facial rows of setae; dactylus outer margin with a distal seta. Pereopods 3–4 ( Figure 9a–b ) similar in shape, basis slender, merus longer than carpus; carpus subequal to propodus; propodus posterior margin with sets of short robust setae; dactylus bearing a nail. Pereopods 5–6 ( Figure 9c–d ) basis posterodistal corner produced as a rounded lobe; merus–propodus subequal in length. Pereopod 7 ( Figure 9e ) basis posterodistal corner produced as a rounded lobe; carpus longer than merus and propodus.

Epimeron 1 ( Figure 10a ) posteroventral corner rounded. Epimera 2–3 ( Figure 10b–c ) posteroventral corner as a spine. Urosomites 1–3 ( Figure 10d–f ) ventral apex produced as a short spine. Uropod 1 ( Figure 10g ) peduncle 1.2× longer than rami, with dorsal and ventral robust setae, distolateral corner with a stronger seta; rami subequal, with several marginal robust setae. Uropod 2 ( Figure 10h ) peduncle subequal to outer ramus, about 0.8× the length of the inner ramus; inner ramus 1.2× longer than outer. Uropod 3 ( Figure 10i ) peduncle about half the length of the rami; inner ramus subequal to outer, with some proximal plumose setae and distal short robust setae; outer ramus article 1 with short robust setae, article 2 about 7% the length of the first article. Telson ( Figure 10j ) apex bifid, each lobe with 1 plumose and 2 robust subapical setae, bearing 2 plumose and 1 robust dorsolateral setae and sparse robust setae.

Etymology

Derived from the type locality, the Potiguar basin (Rio Grande do Norte state) .

Distribution and bathymetry

Known only from the type locality (slope of Rio Grande do Norte state, north-eastern Brazil, between 4.4405°S, 36.4308°W and 4.4905°S, 36.4026°W), between 937 and 1074 m deep ( Figure 23 ).

Remarks

Tectovalopsis has six species; five of them are known from North Pacific thermal vents (13° N), Hess Guyot, Jasper Seamount, and off south-west Mexico, between 706–2884 m (J.L. Barnard and Ingram 1990). The only exception is T. ruffoi ( Serejo and Wakabara, 2003) , which was described from South Atlantic Ocean, south-eastern Brazil (19.01°S, 37.78°W), between 1500 and 1575 m ( Serejo and Wakabara 2003).

Tectovalopsis potiguara sp. n. resembles T. ruffoi in presenting the following: antennal sinus shallow; left mandible lacinia mobilis large and toothed; maxilliped inner plate with 3 short robust apical setae; gnathopods 1–2 ischium and carpus longer than propodus, palms acute; and telson apex bifid, with 2 robust subapical setae. However, the new species differs from T. ruffoi by the following characters (characters of T. ruffoi in parentheses): mandible palp article 3 elongate (shortened); coxa 1 mostly covered by coxa 2 (not covered); gnathopod 1 palm with 2 robust setae near corner (1 robust seta); urosomite 1 with a large dorsal spine (small); uropod 1 peduncle 1.2× longer than rami (as long as rami).

Also, T. potiguara sp. n. is similar to T. nebulosus J.L. Barnard and Ingram 1990 , from Baja California (north Pacific Ocean) due to gnathopod 2 palm strongly acute, epimera 2–3 posteroventral corner as a spine, urosomite 1 with simple dorsal keel, uropod 3 not shortened, and telson apex bifid. However the new species can be distinguished from T. nebulosus by the following characters (characters of T. nebulosus in parentheses): left mandible incisor with 5 teeth (4); maxilla 2 inner plate subequal to outer (distinctly smaller); gnathopod 1 ischium subequal to propodus in length (longer); epimeron 1 posteroventral corner rounded (with a short spine); epimeron 2 lacking facial robust setae (with facial robust setae); urosomite 2 dorsally smooth (with a moderate dorsal tooth).

Figures

Figure 6. Tectovalopsis potiguara sp. n., female hototype, 23 mm (MOUFPE 20190). Habitus. Scale bar: 2 mm.

Figure 7. Tectovalopsis potiguara sp. n., female hototype, 23 mm (MOUFPE 20190). A, head;B, antenna 1; C, antenna 2; D, upper lip; E, lower lip; F, left mandible (partial); G, right mandible; H, maxilla 1; I, maxilla 2; J, maxilliped. Scale bars: A = 1 mm; B, C, G–J = 0.5 mm; D–F = 0.3 mm.

Figure 8. Tectovalopsis potiguara sp. n., female hototype, 23 mm (MOUFPE 20190). A, gnathopod 1; B, gnathopod 2. Scale bars: 1 mm; C, gnathopod 2 inner face of palm.

Figure 9. Tectovalopsis potiguara sp. n., female hototype, 23 mm (MOUFPE 20190). A, pereopod 3; B, pereopod 4; C, pereopod 5; D, pereopod 6; E pereopod 7. Scale bars: 1 mm.

Figure 10. Tectovalopsis potiguara sp. n., female hototype, 23 mm (MOUFPE 20190). A, epimeron 1; B, epimeron 2; C, epimeron 3; D, urosomite 1; E, urosomite 2; F, urosomite 3; G, uropod 1; H, uropod 2; I, uropod 3; J, telson. Scale bars: A–F = 3 mm; G–I = 1 mm; J = 0.5 mm.

Figure 23. Map showing local distribution of the species recorded in the present paper from Potiguar Basin, Rio Grande do Norte state, Brazil.