Alexandrella cedrici 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 : 1643-1648

publication ID	https://doi.org/ 10.1080/00222933.2024.2374404
DOI	https://doi.org/10.5281/zenodo.13785003
persistent identifier	https://treatment.plazi.org/id/2A3B87F7-FFB5-FFFB-FEF2-726EFEEDF900
treatment provided by	Plazi
scientific name	Alexandrella cedrici Souza-Filho, Guedes-Silva & Andrade
status	sp. nov.

Treatment

Alexandrella cedrici Souza-Filho, Guedes-Silva & Andrade sp. n.

( Figures 18–22 View Figure 18 View Figure 19 View Figure 20 View Figure 21 View Figure 22 )

Material examined

Hototype female, 51.6 mm, Potiguar Basin, MT 85 , initial trawl coordinates 4.3559°S, 36.7379°W, final trawl coordinates 4.3669°S, 36.7216°W, Rio Grande do Norte state, Brazil, initial depth 2057 m, final depth 2025 m, 4 May 2011, R / V Seward Johnson col. ( MOUFPE 15086 View Materials ) GoogleMaps .

Type locality

Slope GoogleMaps of Rio Grande do Norte state, north-eastern Brazil, between 4.3559°S, 36.7379°W and 4.3669°S, 36.7216°W.

Diagnosis

Mandible incisors fully and strongly toothed, molar absent; right and left lacinia mobilis large and strongly dentate. Maxilla 1 outer plate with 9 robust setae. Gnathopods 1–2 simple, carpus more robust than propodus, both densely setose. Gnathopod 1 lacking oostegite. Pereonite 7 and pleonite 1 lacking dorsal carina. Pleonites 1–3 with a moderately developed dorsal carina. Urosomite 1 with strong dorsal carina.

Description

Based on female holotype, 51.6 mm, MOUFPE 15086. Body as in Figure 18 View Figure 18 . Head ( Figure 19a View Figure 19 ) lateral cephalic lobe short and blunt, eyes absent. Antenna 1 ( Figure 19b View Figure 19 ) reaching peduncle of antenna 2; peduncle article 1 with a dorsodistal pointed projection; flagellum 27-articulate; accessory flagellum minute, 1-articulate. Antenna 2 ( Figure 19c View Figure 19 ) weakly setose; flagellum 25-articulate. Upper lip ( Figure 19d View Figure 19 ) strongly asymmetrical. Mandibles ( Figure 19e–f View Figure 19 ) incisor fully toothed; molar absent; left lacinia mobilis very large and toothed; right lacinia mobilis almost as large as the left one, strongly toothed; palp 3-articulate, articles 2–3 setose. Maxilla 1 ( Figure 19g View Figure 19 ) inner plate setose, with 5–6 basal pappose setae; outer plate with 9 robust setae; palp 2-articulate, article 2 inner margin widened, with 19 marginal robust setae. Maxilla 2 ( Figure 19h View Figure 19 ) outer plate slightly wider than inner plate. Maxilliped ( Figure 19i View Figure 19 ) inner plate shorter than palp article 1, strongly setose; outer plate strongly exceeding palp, inner margin with row of robust and short setae; palp with marginal setae; article 3 inner margin serrate and bearing a nail distally.

Coxa 1 ( Figure 20a View Figure 20 ) wider than coxa 2 ( Figure 20b View Figure 20 ). Coxa 4 ( Figure 21B View Figure 21 ) with moderate posterior lobe, posterior margin almost straight, ventral margin produced into a rounded lobe. Coxae 5–6 ( Figure 21c–d View Figure 21 ) bilobate, posterior lobe deeper. Gnathopod 1 ( Figure 20a View Figure 20 ) basis slender, setose on both anterior and posterior margin; merus densely setose and slightly longer than ischium; carpus robuster and longer than propodus, setose; propodus setose, 2.5× longer than wide; dactylus inner margin serrate and bearing a nail distally. Gnathopod 2 ( Figure 20b View Figure 20 ) basis slender, anterior margin setose; merus densely setose and slightly longer than ischium; carpus robuster and longer than propodus, setose; propodus setose, 2.7× longer than wide; dactylus inner margin serrate and bearing a nail distally. Pereopods 3–4 ( Figure 21a–b View Figure 21 ) similar in shape, basis slender, merus longer than carpus, anterior margin slightly produced distally; carpus–dactylus with marginal short robust setae. Pereopods 5–6 ( Figure 21c–d View Figure 21 ) basis suboval, posterodistal corner slightly produced into a rounded lobe; merus with posterodistal corner produced into a subacute lobe; carpus–dactylus with marginal short robust setae; dactylus long. Pereopod 7 ( Figure 21e View Figure 21 ) basis with posterior margin strongly excavated, forming a lobe proximally and distally; dactylus about 0.8× the length of the propodus.

Pereonite 7 and pleonite 1 ( Figure 18 View Figure 18 ) lacking dorsal carina. Pleonites 1–3 ( Figure 22a–c View Figure 22 ) with a moderately developed dorsal carina. Epimera 2–3 ( Figure 22b–c View Figure 22 ) posteroventral corner produced into a short spine. Urosomite 1 ( Figure 22d View Figure 22 ) with a dorsal well-developed carina, preceded by a distinct ‘U-shaped’ notch. Uropod 1 ( Figure 22e View Figure 22 ) peduncle subequal to outer ramus, with only 1 dorsal robust seta medially; inner ramus broken; outer ramus tapering distally and naked. Uropod 2 ( Figure 22f View Figure 22 ) peduncle 0.8× shorter than outer ramus; only outer ramus with 4 short marginal robust setae. Uropod 3 ( Figure 22g View Figure 22 ) peduncle much shorter than rami, which are broken at tip. Telson ( Figure 22h View Figure 22 ) about 45% cleft, each lobe rounded.

Etymology

The specific epithet is dedicated to Dr Cédric d’Udekem d’Acoz, for his great contribution to the taxonomy of amphipods and more recently to the genus Alexandrella .

Distribution and bathymetry

Known GoogleMaps only from the type locality (slope of Rio Grande do Norte state, north-eastern Brazil, 4.3559°S, 36.7379°W and 4.3669°S, 36.7216°W), between 2025 and 2057 m deep ( Figure 23 View Figure 23 ).

Remarks

A unique specimen of Al. cedrici sp. n. was collected at 2057 m. The new species resembles Al. inermis Bellan-Santini and Ledoyer, 1987 in presenting antenna 1 shorter than antenna 2, mandible incisors toothed along the entire margin, female gnathopod 1 without oostegite, gnathopods 1–2 simple, pleonite 3 with a short-medium dorsal carina. Even so, Al. cedrici sp. n. can be distinguished from Al. inermis by the following (characters of A. inermis in parentheses): right mandible lacinia mobilis present (absent); pereopod 4 coxa posterior margin almost straight (concave), dactylus long (short); epimera 3 posteroventral corner produced into a short spine (rounded); telson cleft (entire).

Alexandrella cedrici sp. n. also has some characters in common with Al. pulchra Ren in Ren and Huang, 1991 and Al. schellenbergi Holman and Watling, 1983 such as: antenna 1 peduncle article 1 with short dorsomedial tooth; pereopod 4 coxa posterior margin almost straight, dactylus long. The new species can be readily differentiated from the aforementioned species by presenting short-medium dorsal carinae on pleonites 1–3, whereas they present large acute carinae. This is the first record of the family Stilipedidae from Brazil.