Alexandrella setosa, Serejo, C. S., 2014

Serejo, C. S., 2014, A new species of Stilipedidae (Amphipoda: Senticaudata) from the South Mid- Atlantic Ridge, Zootaxa 3852 (1), pp. 133-140 : 135-137

publication ID	https://doi.org/ 10.11646/zootaxa.3852.1.6
publication LSID	lsid:zoobank.org:pub:F2D4DB10-3F03-4482-A444-B7493841A0C7
DOI	https://doi.org/10.5281/zenodo.6139041
persistent identifier	https://treatment.plazi.org/id/038E87A3-5D4F-CD2D-FF1D-FBFC1027C777
treatment provided by	Plazi
scientific name	Alexandrella setosa
status	sp. nov.

Treatment

Alexandrella setosa View in CoL sp. nov.

( Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Material examined. Holotype, male, 17.9 mm, superstation 7, serial number 1030, Walvis Ridge Sector (WRS), 29o29.87’S 0 1o 10.06’E, 4120 m, MNRJ 23520. Allotype, female, 18 mm, same as type locality, MNRJ 23763. Paratypes: 2 females, 19 mm, 19.3 mm, same as type locality, MNRJ 23764.

Etymology. from the Greek Setose that corresponds to the densely setose condition of gnathopods 1 and 2.

Diagnosis. Mandible, incisors fully toothed, molar absent; maxilla 1 outer plate with 36–40 setal-teeth. Gnathopods 1–2 subchelate, carpus and propodus densely setose. Pleonites 1–3 and urosomite 1 strongly toothed.

Description. Based on holotype, male 17.9 mm, MNRJ 23520. Eyes absent. Upper lip strongly asymmetrical. Mandible, incisor fully toothed; molar absent; left lacinia mobilis very large and toothed; right lacinia much smaller than left one, slightly toothed palp 3-articulated. Lower lip without inner lobe. Maxilla 1, palp 2- articulated, second article widening distally, with 28–30 distal robust setae and 9–10 sub distal slender setae; outer plate with 36–40 setal teeth; inner plate setose, with 5–6 basal pappose setae. Maxilla 2 outer plate slightly wider than inner plate; inner plate with several basal pappose setae. Maxilliped outer plate strongly exceeding palp, serrate medially; inner plate extending past distal margin of palp article 1; palp with marginal setae.

Coxa 1 wider than coxae 2–3. Coxa 4 excavated posteriorly, ventral margin rounded. Gnathopods 1–2 subchelate, palm excavate proximally, broadly rounded distally, with 10–11 robust setae at palm corner; propodus and carpus densely setose; dactylus slightly curved, inner margin with sparse setae. Basis of pereopods 5–6 with medial ridge. Basis of pereopod 7 expanded proximally forming a posterior lobe, posterodistal lobe rounded.

Pleonites 1–3 and urosomite 1 strongly toothed. Epimeron 2 with posteroventral tooth. Epimeron 3 subquadrate. Uropod 1, peduncle apparently longer than rami, which are broken at tip. Uropod 2 peduncle subequal to inner ramus; inner ramus 1.6 × outer ramus length; both rami with marginal row of setae on medial side. Uropod 3 peduncle much shorter than rami, which are broken at tip. Telson emarginated, as long as wide.

Female. Gnathopods 1–2 subchelate, palm slightly oblique, with 3 robust setae; propodus and carpus densely setose; dactylus straight and distinctly serrate. Oostegites present on pereopods 2–5.

Distribution. Atlantic Ocean: Walvis Ridge, 29o29.87’S 0 1o 10.06’E, 4120 m.

Remarks. Alexandrella setosa sp. nov is closely related to A. subchelata as both species present gnathopods 1–2 subchelate, which is a unique character within the genus. The new species can be distinguished from A. subchelata by the maxilla 1 outer plate with 36–40 setal teeth (versus 26 setal-teeth); maxilla 1 palp with 28–30 robust setae (versus 16 robust setae); gnathopods 1–2 densely setose on facial margins of carpus and propodus and pleonites 1–3 dorsally with well developed pointed teeth.